PCS POCKET PHONE/MICROCELL COMMUNICATION OVER-AIR PROTOCOL

Abstract: A simple and flexible over-air protocol for use with a mobile telephone system, having hand-held telephones (102) in a microcell or other type of cellular communication system. A method in which user stations (102) communicate with one or more base stations (104) to place and receive telephone calls, in which the user stations (102) are provided a secure voice or data link and have the ability to handoff calls between base stations (104) while such calls are in progress. Each base station (104) has a set of "air channels" to which it transmits in sequence. The air channels supported by each base station (104) are called that base station's polling loop. A user station (102) receives general polling information on an unoccupied air channel, transmists responsive information to the base station, and awaits acknowledgement from the base station. Each base station (104) may therefore simultaneously maintain communication with as many user stations (102) as there are air channels in its polling loop. The ability of a user station (102) to communicate on any unoccupied air channel makes the protocol air-channel agile, while the stability of user station and base station clocks may define air channels, gaps, and minor frames.

Description: S P E C I F I C A T I O N TITLE OF THE INVENTION P C S POCKET PHONE/MICROCELL COMMUNICATION OVER-AIR PROTOCOL BACKGROUND OF THE INVENTION Related Application Data This application claims priority from U.S. Application No. 08/215,306 filed on March 21, 1994 and U.S. Application No. 08/284,053 filed on August 1, 1994, both entitled "P C S POCKET PHONE/MICROCELL COMMUNICATION OVER-AIR PROTOCOL, " both of which are continuation-in-part applications of U.S. Application Serial No. 08/146,496 filed on November 1, 1993, bearing the same title, and now abandoned. Field of the Invention This invention relates to the field of communications, and particularly to communication systems using spread spectrum techniques and to over-the-air protocols for mobile telephones. Description of Related Art A mobile telephone system may generally comprise a set of "user stations", typically mobile and the endpoints of a communication path, and a set of "base stations", typically stationary and the intermediaries by which a communication path may be established or maintained. In a mobile telephone system, one important concern is the ability of mobile stations to communicate with base stations in a simple, flexible and rapid manner. The communication protocol between user stations and base stations should be rapid, so that user stations are not required to wait to establish a communication path. The protocol should be simple, so that user stations need not incorporate expensive equipment to implement it. The protocol should be flexible, so that user stations may establish communication paths in as many communication environments as reasonably possible. Accordingly, it would be advantageous to provide a simple and flexible over-air protocol for use with a mobile telephone system. One class of systems in which this would be particularly advantageous is that of personal communication systems, particularly those with hand-held telephones in a microcell or other type of cellular communication system. SUMMARY OF THE INVENTION The invention provides in one aspect a simple and flexible over-air protocol for use with a mobile telephone system, such as a Personal Communication System (PCS) with hand-held telephones in a cellular communication system. A preferred embodiment is adapted to "pocket phones", i.e., small hand-held telephones which may use a cellular communication technique, but the invention may be used with any cellular or mobile telephone system. The protocol defines a method in which user stations, such as cellular or mobile telephone handsets, communicate with one or more base stations to place and receive telephone calls. The protocol provides air-channel agility between base stations and user stations, while providing a secure voice or data link and the ability to handoff calls between base stations while they are in progress. In a preferred embodiment, each base station may have a set of "air channels" which it polls, e.g. by transmitting to each one in sequence. The air channels supported by each base station are referred to as a "polling loop" for a particular base station. A user station may receive information on an unoccupied air channel, receive the base station's transmission, and transmit information to the base station. Each base station may therefore simultaneously maintain communication with as many user stations as there are air channels in its polling loop. The ability of a user station to communicate on any unoccupied air channel makes the protocol air-channel agile. Each base station continually transmits on each one of its air channels in a predetermined sequence. Each base station transmission may be followed by a first gap, a user station transmission (if some user station attempts to communicate) , and a second gap, before the base station transmits on the next air channel . A base station transmission, first gap, user station transmission, and second gap are collectively called a "minor frame" . A polling loop in which each air channel is polled is called a "major frame" . In a preferred embodiment, stability of user station and base station clocks may define the air channels, gaps, and minor frames. The user station may synchronize itself to the base station's clock by detecting a minor frame and by adjusting its clock to be in synchrony with the base station when the first bit sequence of the minor frame is detected. The stability of the user station and base station clocks may then hold the user station and base station in synchronization, as long as the user station is periodically able to receive transmissions from the base station. Should reception in either direction be interrupted for too long, the base station and user station clocks may drift apart and the user station may need to reacquire the transmission from the base station. Handoffs are preferably initiated from the user station which continually monitors available air channels from the same and competing base stations during dead time. A user station may handoff within the same polling loop to establish communication in a new minor frame, or may handoff in such a manner to establish communication in a new minor frame within a polling loop of a different base station. In the latter case, a base station controller may assist in transferring the call from one base station to another. The invention provides in yet another aspect for closed loop power control in the user stations by monitoring and adjusting the user station power at regular intervals, such as once in each major frame. The control of user station power serves to reduce intercell interference and prolong battery life in mobile handsets. Variable data rates provided in another aspect of the present invention. A user station may increase its data rate by transmitting and/or receiving in multiple minor frames during a major frame, or may reduce its data rate by transmitting and/or receiving in fewer than every major frame. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a diagram of a communication system having base stations and user stations. Figure 1-1 is a diagram of a communication system with alternate network interconnections. Figure 1-2 is a diagram of a network architecture showing various system components . Figure 1-3 is a diagram of a network architecture showing connections between base stations and a network. Figures 1-4, 1-5, 1-6, and 1-7 are diagrams of network architectures showing various system components. Figures 1-8 and 1-9 are diagrams of a handset air channel acquisition procedure for an embodiment of the invention. Figure 2 is a diagram of frame and message formats in a polling loop. Figure 2-1 is a diagram of a preferred cellular environment in which the invention may operate. Figure 2-2 is a diagram of a TDMA/TDD frame structure for an embodiment of the invention. Figure 2-3 is a diagram of a polling loop for an embodiment of the invention. Figure 2-4 is a block diagram of a speech coder for an embodiment of the invention. Figure 2-5 is a functional block diagram of a speech coder control path for an embodiment of the invention. Figure 2-6 is a diagram of a packet structure for an embodiment of the invention. Figure 2-7 and 2-8 are diagrams showing time slot assignments for an embodiment of the invention. Figure 2-9 is a diagram of a speech coder buffer structure for an embodiment of the invention. Figure 3 is a diagram showing formats for message types. Figures 3-1 and 3-2 are estimated cell radii coverage charts for an embodiment of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENT In a preferred embodiment, it is contemplated that communication between base stations and user stations will be conducted using a spread-spectrum technique. There are at least three methods for establishing synchronization and communication, each preferably using an M-ary technique in which multiple bits of data are transmitted for each spread- spectrum symbol, e.g., by transmitting and receiving multiple different spreading codes, and interpreting the received one of those multiple different spreading codes at the receiver to indicate multiple data bits. Synchronization may be accomplished either by (1) automatic synchronization disclosed in U.S. Application Serial No. 08/146/491, entitled "DESPREADING/DEMODULATING DIRECT SEQUENCE SPREAD SPECTRUM SIGNALS", Lyon & Lyon Docket No. 200/154, filed on November 1, 1993 in the name of inventors Robert Gold and Robert C. Dixon, hereby incorporated by reference, by (2) synchronizing with matched filters, by (3) demodulation and despreading using sliding correlators, or by (4) a combination of these techniques, e.g., matched filters for synchronization plus sliding correlators for demodulation and despreading, or matched filters for synchronization plus autosynchronization for demodulation and despreading. Figure 1A is a diagram of a communication system having base stations and user stations. A communication system 101 for communication among a plurality of user stations 102 may include a plurality of cells 103, each with a base station 104, typically located at the center of the cell 103. Each station (both the base stations 104 and the user stations 102) may generally comprise a receiver and a transmitter. The user stations 102 and base stations 104 preferably communicate using time division multiple access (TDMA) or time division duplex (TDD) techniques as further described herein, in which specified 5 time segments or major frames are divided into assigned time slots or minor frames for individual communication. Figure 2-1 is a diagram of a preferred cellular environment in which the invention may operate. A geographical region is divided into a plurality of cells 103. 10 Associated with each cell 103 is an assigned frequency and an assigned spread spectrum code. Preferably, three different frequencies Fl, F2 and F3 are assigned in such a manner that no two adjacent cells have the same assigned frequency Fl, F2 or F3. The effect of such a frequency reuse pattern is to 15. minimize interference between adjacent cells. To further reduce the possibility of intercell interference, different orthogonal spread spectrum codes Cl through C6 are assigned as shown in adjacent clusters 110. Although six spread spectrum codes Cl through C6 are shown in 20 Fig. 2-1, it is contemplated that fewer or more spread spectrum codes may be suitable depending upon the particular information. Further information regarding a preferred cellular environment may be found in U.S. Application Serial No. 07/682,050 entitled "Three Cell Wireless Communication 25 System" filed on April 8, 1991 in the name of Robert C. Dixon, and hereby incorporated by reference as if fully set forth herein. The use of spread spectrum for carrier modulation permits a very efficient frequency reuse factor of N = 3 for 30 allocating different carrier frequencies Fl, F2 and F3 to adjacent cells 103. Interference between cells 103 using the same carrier frequency Fl, F2 or F3 is reduced by the propagation loss due to the distance separating the cells 103 (no two cells 103 using the same frequency Fl, F2 or F3 are 35 less than two cells 103 in distance away from one another) , and also by the spread spectrum processing gain of cells 103 using the same carrier frequencies Fl, F2 or F3. The preferred spread spectrum bandwidth may differ according to the frequency band of operation. When operating in the PCS A, B, or C frequency bands, each of which is 15 Mhz wide, the center frequencies Fl, F2 and F3 are preferably located at 2.5 Mhz, 7.5 Mhz, and 12.5 Mhz, respectively, from the lowest band edge of the A, B or C frequency band. The PCS D, E, or F bands, on the other hand, are each 5 Mhz wide, which is the same bandwidth as a preferred spreading bandwidth for a spread spectrum signal used in the particular cellular environment. Consequently, a single carrier frequency is placed in the center of the D, E or F band, and a frequency reuse factor of N = 1 is used because the spread spectrum signal covers the entire available bandwidth. Because an N = 1 frequency reuse pattern is used, the required intercell interference rejection must be obtained by spread spectrum code orthogonality and/or the use of sectorized antenna patterns. The exchange of interfering air channels or time slots, as described elsewhere herein, may also be used to mitigate intercell interference. When operating in the PCS unlicensed band, which has a bandwidth of 20 Mhz divided into individual channel only 1.25 MHz wide, the spread spectrum chipping rate may be reduced to approximately 1.25 Mcps. The TDMA burst rate, or number of TDMA time slots (or minor frames) in each polling loop, may also be reduced to maintain the required spread spectrum processing gain for rejecting intercell interference. A non-spread spectrum TDMA/TDD signal modulation format for operation in the unlicensed band may also be provided. Figure 1-2 is a diagram of a network architecture showing various system components. A preferred communication system is designed around an object-based software architecture which allows for flexibility in interconnection to various networks including public switched telephone networks, AIN, GSM and IS-41 network infrastructures. It is also contemplated that the communication system may interface with a cable television distribution network; however, such an interface may require the addition to the cable television network of a switch architecture, two-way amplifiers, redundancy, and, in order to use the coaxial portion of the cable TV network, a remote antenna subsystem to extend coverage from a base station 104. The overall system thus provides flexibility to interface with a variety of different networks depending upon the desired application. To allow interconnection to diverse networks, the system uses internal communications based on ISDN messages, called "notes", for passing necessary information among components within the system. These "notes" are so named as not to confuse them with the ISDN specific protocol itself. Network messages (based on, e.g., Q.921, Q.931 protocols, or others) are converted by the system into "notes" for efficient operation within the hardware platform. In Fig. 1-2 is shown various components of a preferred system architecture including a plurality of base stations 104 for communicating with user stations 102. Each base station 104 may be coupled to a base station controller 105 by any of a variety of linking means 109 including, for example, local area data access (LADA) lines, Tl or fractional Tl lines, ISDN BRI's, cable TV lines, fiber optic cable, digital radio, microwave links, or private lines. As an illustration shown in Fig. 1-2, a plurality of base stations 104 may be coupled to base station controller 105 by first connecting to a coaxial cable 111 which is thereafter coupled to a fiber optic cable 113 at a fiber node 112. The fiber optic cable 113 is coupled to the base station controller 105 as shown. Each base station controller 105 may be connected to a network 106 such as a public switched telephone network (PSTN) or a personal communications system switching center (PCSC) by a variety of network links 108, which include the same basic categories of transport means as the linking means 109. Base station controllers 105 may also connect to the network 106 via an X.25 link 114. The system of Fig. 1-2 also incorporates the use of "intelligent" base station (IBS) 107 compatible with LEC-based AIN architecture that may be connected directly to a network 106 without the interface of a base station controller 105. The intelligent base stations 107 may therefore bypass the base station controllers 105 for local handoffs and switching, and instead perform these functions via the network 106. In AIN based architectures, signaling between network elements may be carried out using standard signaling protocols including, for example, SS7 and IS-41. In operation, the base stations 104 format and send digital information to the base station controller 105 (or directly to the network 106 in the case of an intelligent base station 107) . The base station controllers 105 concentrate inputs from multiple base stations 104, assist handoffs between base stations 104, and convert and format channel information and signaling information for delivery to the network 106. The base station controllers 105 may also manage a local cache VLR database, and may support basic operations, administration and management functions such as billing, monitoring and testing. Each base station controller 105, under control of the network 106, may manage local registration and verification of its associated base stations 104 and may provide updates to the network 106 regarding the status of the base stations 104. The network 106 connects to the base station controllers 105 for call delivery and outgoing calls. The connection between the network 106 and a base station controller 105 may utilize the Bellcore "Generic C" interface which includes Q.921, Q.931 and modifications to Q.931. Intelligent base stations 107 may use ISDN messaging for registration, call delivery and handoff over a public telephone switch. The intelligent base station 107 may have all the general capabilities of a base station 104 but further incorporate a BRI card, additional intelligence and local vocoding. The connection between the network 106 and an intelligent base station 107 may utilize the Bellcore "Generic C" interface which includes Q.921, Q.931 and modifications to Q.931. If the network 106 is a GSM network, then base stations 104 may connect to the network 106 through a defined "A" interface. Features and functionality of GSM are passed to and from the base stations 104 over the "A" interface in a manner that is transparent to the end user. As noted, the system may also interconnect to cable television distribution networks. The base stations 104 may be miniaturized to the point where they can be installed inside standard cable TV amplifier boxes. Interfacing may be carried out using analog remote antenna systems and digital transport mechanisms. For example, Tl and FT1 digital multiplexer outputs from the cable TV network may be used for interfacing, and basic rate (BRI) ISDN links to transport digital channels. Cell site diagnostics may be performed remotely through either the control channel on the digital link resident in the base station 104 or a dial up modem for some implementations. Such diagnostics may be performed on each component board of the base station 104. In addition, the base stations 104 and base station controllers 105 may be remotely monitored and downloaded with updated software as required. Similarly, user stations 102 can also be downloaded with software over air channels as required for maintenance purposes or for system upgrades. The user stations 102 comprise in one embodiment mobile handsets capable of multi-band and/or multi-mode operation. The user stations 102 may be multi-mode in that they may be capable of either spread spectrum communication or conventional narrowband communication. The user stations 102 may be multi-band in the sense that they may be set to operate on a plurality of different frequencies, such as frequencies in either the licensed or unlicensed frequency bands. For example, a user station 102 may be set to operate on any frequency between 1850 and 1990 MHz in 625 kHz steps. Thus, each user station 102 may have a frequency synthesizers which can be programmed to receive and transmit on any one of 223 frequencies. If the user station 102 operates solely in the licensed PCS band, however, the programmable frequency steps may be in 5 MHz increments, in which case the first channel may be centered at 1852.5 MHz, the next at 1857.5 MHz, and so on. If operating in the isochronous band between 1920 and 1930 MHz, the first channel may be centered at 1920.625 MHz, and the channel spacing may be 1.25 MHz across the remainder of the isochronous band. The user stations 102 need not operate in the 1910 to 1920 MHz band, which is reserved for asynchronous unlicensed devices. Further detail regarding the multi-band and multi- mode aspects of user stations 102 may be found in U.S. Application Serial No. 08/146,492 filed on November 1, 1993 in the name of inventors Robert C. Dixon and Jeffrey S. Vanderpool, entitled "DUAL-MODE WIRELESS UNIT WITH TWO SPREAD- SPECTRUM FREQUENCY BANDS," U.S. Application Serial No. 08/059,021 filed May 4, 1993 in the name of inventors Douglas G. Smith, Robert C. Dixon and Jeffrey S. Vanderpool, entitled "DUAL-BAND SPREAD-SPECTRUM COMMUNICATION," and U.S. Application Serial No. 08/206,045 filed on March 1, 1994 in the name of inventors Robert C. Dixon and Jeffrey S. Vanderpool, entitled "DUAL-MODE TRANSMITTER AND RECEIVER," each of which is hereby incorporated by reference as if fully set forth herein. The multi-band, multi-mode capability enables the user stations 102 take advantage of variety of diverse system architectures as described herein, and to interface with various different networks with a minimum of hardware or software adjustments. Base stations 104, like user stations 102, may also be provided with multi-band and multi-mode capabilities as described above. FRAME AND MESSAGE FORMATS Figure 2 shows frame and message formats in a polling loop. In a single cell 103, a base station 104 may poll user stations 102 in the cell 103. The base station 104 may repeatedly transmit a major frame 201, comprising a sequence of minor frames 202. As noted herein, each minor frame 202 may comprise a polling exchange for a single user station 102, while each major frame 201 may comprise a complete polling sweep of user stations 102 in the cell 103. In a preferred embodiment, the base station 104 may conduct its polling exchanges using a set of air channels 203. Each of the air channels 203 may comprise a separate transmission channel, such as a separate frequency band for FM or AM encoding, a separate spreading code for spread-spectrum encoding, a separate spatial location, or other division of communication slots between base stations 104 and user stations 102. In a preferred embodiment, the base station 104 may poll every one of its air channels 203 in a predetermined sequence in a single major frame 201. While in a preferred embodiment, the base station 104 may poll every one of its air channels 203 in a single major frame 201, but it will be clear to those of ordinary skill in the art, after perusal of this application, that the base station 104 may restrict its poll to only a portion of its air channels 203 in each major frame 201, so long as all air channels 203 are eventually polled, and in an order so that each user station 102 may determine in which minor frame 202 it should respond. Each minor frame 202 may comprise a base transmission 204 by the base station 104, a first gap 205, a user transmission 206 by a user station 102 (if any user station 102 responds) , and a second gap 207. During the base transmission 204, a user station 102 desiring to establish a communication path may receive the base transmission 204 and determine if the air channel 203 is occupied or not. If not occupied, the user station 102 may respond with its user transmission 206. In one embodiment, in order to provide efficient service in low density rural areas, cell radii can be extended to large distances (e.g., beyond 8 miles) by providing the increased guard times as would be required for the longer round trip propagation delays encountered in the larger cells. Cells with large radii can be supported by reducing the number of minor frames 202 per major frame 201 to a lesser number (e.g., from 32 to 25) . Since such large cell radii will ordinarily be deployed in low population density areas, reduced cell capacity caused by the smaller number of minor frames 202 per major frame 201 is not a severe drawback. In a preferred embodiment, a base transmission 204 may comprise a header field 207, which may be a fixed length of sixteen bits, a D field 208, which may be a fixed length of eight bits, and a B field 209, which may be a fixed length of 160 bits, or may be a variable length. In an embodiment using a variable-length B field 209, the variable length may be determined in response to the polling loop time and the data rate which must be supported. For example, in a preferred embodiment of a 30-channel system, the B field 209 may be 160 bits long. In a preferred embodiment, the user transmission 206 may comprise like fields as the base transmission 204. The header field 207 may comprise an origin bit 210, which may be a "1" bit for base transmissions 204 and may be a "0" bit for user transmissions 206. Other parts of the header field 207 may indicate information about the base transmission 204 or user transmission 206 itself, e.g., what type of message the base transmission 204 or user transmission 206 comprises. The header field 207 may also comprise a CSC or CRC code 211 (a cyclic redundancy check) having four bits. The D field 208 may comprise control information to be communicated between base stations 104 and user stations 102 once a communication link is established. This control information may generally be used for ISDN communication between base stations 104 and user stations 102, such as control information generally communicated using the ISDN "D channel". Because the D field 208 is separate from but simultaneous with the B field 209 which normally handles the bulk of information transfer due to its higher data rate, the D field 208 may be used for paging applications, notifications (e.g., voice mail), short message service (similar to GSM), or other user applications. Thus, the simultaneous nature of the D field 208 and the B field 209 allows messaging functions even when the user station 102 is "in use". During link expansion, described with regard to figure 3 herein, the D field 208 may also comprise a user nickname 212 for communication from the base station 104 and a designated user station 102. The user nickname 212 may comprise a temporary identifier for the user station 102 selected by the base station 104. The B field 209 may comprise data, voice (encoded digitally or otherwise) , or other information. In a preferred embodiment, the B field 209 may also comprise specified information for establishing communication links between base stations 104 and user stations 102. The B field 209 may also comprise its own FCW or CRC code 211 having sixteen bits (with 160 bits of information, a total of 176 bits) . In a preferred embodiment, there may be 32 air channels 203; the major frame 201 may therefore comprise 32 minor frames 202 in sequence. Thus, each minor frame 202 may be about 307 microseconds long, each air channel 203 (in a TDD or TDMA system) may be about 667 microseconds long, and each major frame 201 may be about 20 milliseconds long. In a preferred embodiment, there may be 160 bits transmitted per air channel 203; thus the 32-channel system would have about a 256 kilobits/second total two-way data rate. Other time values are shown in the figure. In a preferred embodiment, information may be transmitted at a rate of five bits each 6.4 microseconds, using a 32-ary code-shift keying technique. Thus, each 6.4 microseconds, one of 32 different codes may be transmitted, with 32 different possibilities equalling five bits of information. In an alternative preferred embodiment, one of 16 different codes may be transmitted, with an additional phase bit on the carrier (or, in a second alternative, more than one phase bit on the carrier) , again with 32 different possibilities equalling five bits of information. In one embodiment, a minor frame 203 may operate in an asymmetric mode in the sense that the greater portion of a minor frame 202 is devoted to either the base transmission 204 or the user transmission 206. High speed data transport in either direction (i.e., from the base station 104 to the user station 102, or vice versa) can be provided in the asymmetric mode, with or without acknowledgment and/or ARQ. A particular sub-mode of the above described asymmetric mode may be referred to as broadcast mode in which essentially the entire minor frame is devoted to one-way communication. In the broadcast mode, one or more broadcast sub-channels may be identified by a special broadcast identifier. Up to 255 broadcast channels may be so identified. For these point-to-multipoint applications, broadcast frames are not acknowledged. Control Pulse A user station 102 in a cellular environment preferably has means for controlling transmission power to avoid interference with adjacent cells. Unlike a fixed station environment, in which antenna locations, patterns and fixed station transmission power may be adjusted for minimal interference with other fixed stations, the nature of a cellular environment with mobile user stations 102 is such that there can arise conflict between user stations 102 at intersecting cell boundaries. This creates the need for some power control in the user stations 102. For example, a user station 102 operating at the boundary of coverage of a base station 104 may need to transmit at full power to stay in contact. On the other hand, a user station 102 operating relatively close to its own base station 104 may not need to transmit full power to have good contact. By proper power control, user stations 102 may maintain adequate contact with base stations 104 without unduly interfering with neighboring cell transmissions, allowing RF channel reuse in nearby cells. Power control may also reduce interference with fixed microwave users and conserve battery power in user stations 102 such as handheld units. The present invention achieves power control in one embodiment by use of a power control pulse transmitted periodically from each user station 102. After establishment of a communication link, described with regard to Fig. 3 herein, a control pulse time 213 and a third gap 214 may be reserved just prior to the start of the minor frame 202, in which the user station 102 transmits a control pulse 215. The control pulse 215 provides to the base station 104 a power measurement of the air channel 203 indicative of the path transmission loss and link quality. Each user station 102 generally transmits its control pulse 215 in the minor frame 202 allocated to it (e.g., seized by the user station 102) . The control pulse 215 may be received by the base station 104 and used by the base station 104 to determine information about the communication link it has with the user station 102. For example, the base station 104 may determine, in response to the power, envelope, or phase of the control pulse 215, the direction or distance of the user station 104, and the degree of noise or multipath error to which the communication link with the user station 102 may be prone. In response to receiving the control pulse 215, the base station 104 determines the quality of the received signal including, for example, the received power from the power control pulse 215 and the signal-to-noise or interference ratio. The base station 104 then sends a message to inform the user station 102 to adjust its power if needed. Based on the quality of the received signal, the base station 104 may command the user station 102 to change (increase or decrease) its transmit power by some discrete amount (e.g, in minimum steps of 3 dB) relative to its current setting, until the quality of the control pulse 215 received by the base station 104 is above an acceptable threshold. Similarly, if the base station 104 knows the power setting of the user station 102, then the base station 104 can adjust its own power as well. The base station 104 may adjust its power separately for each minor frame 202. A preferred power control command pulse from the base station 104 to the user station 102 may be encoded according to Table 5-1 below: Although preferred values are provided in Table 5-1, the number of power control command steps and the differential in power adjustment between steps may vary depending upon the particular application and the system specifications. While power control is thus desirable, a problem in some conventional TDMA systems is that the length of the polling loop (e.g, the major frame 201) is too long to allow the latest user transmission to be very useful for estimating the channel losses and impairments. In other words, the latency of the polling loop signals may prevent the use of closed loop power control. However, the described embodiment allows for a power control sequence that may be effectively carried out in a relatively short span of time, thereby allowing closed loop power control . Preferably, the elapsed time encompassing transmission of the control pulse 215, the base transmission 204, and the start of the user transmission 206 is kept relatively short (e.g., less than 500 μsec or roughly 2.5% of the duration of the major frame 201) , allowing system response to be fast enough to counteract small scale multipath fading effects and propagation shadow effects. The base station 104 may also use the control pulse 215 to measure the time delay from a user station 102 and thereby estimate the distance of the user station 102 from the base station 104. For 911 support, a user station 102 can provide control pulses 215 to multiple base stations 104 for rough location estimation in emergency situations. In a preferred embodiment, the base station 104 may have a plurality of antennas for reception and transmission on the communication link with the user station 102, and may select one of that plurality of antennas for reception and/or transmission, in response to the determination the base station 104 may make in response to the control pulse 215. The base station 104 may make the determination of which antenna to use based on the quality of the signal received from the control pulse 215 transmitted by the user station 102. Because the base station can both receive and transmit on the antenna having the best received signal quality from the control pulse 215, the user stations 102 benefit from antenna selection diversity even though they might not have explicit antenna diversity capabilities at the user station 102. The control pulse 215 permits spatial diversity control to be updated during each minor frame 202. Preferably, the base station 104 employs a high speed TDD technique such that the RF channel characteristics do not change within the time of the minor frame 202. Information relating to the control pulse 215 for a particular user station 102 may be transferred as information in control traffic from one base station 104 to another base station 104 in the case of a base station assisted handoff. It should be noted that, in the preferred TDMA system described herein, the requirement of strict RF transmitter output power control is not necessary to resolve the "near-far" problem commonly experienced in CDMA systems. . The purpose of the control pulse 215 is primarily to reduce battery consumption in user stations 102, to minimize interference of transmissions among neighboring cells 103 which may be operating on the same or adjacent RF channels, and to minimize interference with nearby fixed microwave users. The control pulse 215 may also serve as a synchronization preamble for determining the beginning of M-ary data symbols within the minor frame 202. A power control command pulse, similar in length to the control pulse 215, transmitted by the base station 104 during the base transmission 204 or otherwise may likewise be used as a synchronization preamble at the user station 102, in addition to providing a power control command to adjust the power output level at the user station 102. Base Station Output Power Because a single base station 104 may communicate with a large number of user stations 102 (e.g., as many as 64 user stations 102) at a given time, each of whose distance from the base station 104 may vary from near zero up to the radius of the cell 103, it may not be practical to control the transmitter power of the base station 104 in order to maintain a near-constant received power level at each user station 102 during each minor frame 202. Output power control of the transmitter at the base station 104 could require a large change (e.g., more than 40 dB) in transmit power during each minor frame 202 (e.g., every 625 μs) of the major frame 201. As an alternative to providing power control on a minor frame 202 by minor frame 202 basis, output power control at the base station 104 can be averaged over a longer time interval than each minor frame 202. Antenna Characteristics In one aspect of the invention, the reciprocal nature of time division duplex (TDD) permits common antennas to be used for transmit and receive functions at both the base station 104 and the user stations 102, without the need for antenna diplexers. Common antennas can be used to transmit and receive because these functions are separated in time at each of the terminals. Further, because TDD utilizes the same RF frequency for the transmit and receive functions, the channel characteristics are essentially the same for both the base station 104 and a particular user station 102. The use of common antennas results in simplicity of the base station 104 and user station 102 terminal designs. Further, use of the same RF frequency and antenna for both transmit and receive functions at the base station 104 and the user station 102 provides reciprocal propagation paths between the base station 104 and user station 102 terminals. This reciprocal nature allows the base station 104 to use the channel sounding of the control pulse 215 transmitted by the user station 102 to determine the two-way path loss between the base station 104 and the user station 102, and also to determine which of the spatial diversity antennas at the base station 104 to use, both to receive from the user station 102 and to transmit to the user station 102. Different types of antennas may be used by the base station 104, depending on the type of application. For low density suburban or rural applications an omnidirectional antenna may be used to provide maximum coverage with the fewest base stations 104. For example, an omnidirectional antenna may be employed having a vertical gain of approximately 9 dB. The 9 dB of gain permits a relatively large radius cell even with an omnidirectional horizontal pattern. In suburban and low density urban areas, directional antennas with 120 degree azimuth beamwidths and 9 dB vertical gain may be used at the base station 104 so that a cell 103 can be sectorized into three parts, with each sector accommodating a full load of user stations 102 (e.g., 32 full duplex user stations 102) . The use of TDD also permits utilization of a single steered phased array antenna at the base station 104 for applications requiring a high gain, highly directional antenna. Similar deployment in CDMA or FDMA systems would, in contrast, be more complex and costly, as they may require simultaneous steered beams for each user station 102 within the cell 103. For example, to permit a single base station 104 to cover large, sparsely populated area, a steered array antenna with up to 20 dB of horizontal directivity can be used. Such an antenna is sequentially steered to each user station 102 within a cell 103 at each minor frame 202. The same antenna may be used for both transmission and reception, as noted, providing reciprocal forward and reverse link propagation characteristics. The steered array antenna may utilize circular polarization so that high level delayed clutter ■ signals reflected from buildings or other obstructions within the beam path do not interfere with the received signals from the user stations 102. As reflected signals are typically reversed in polarization, they will be rejected by the circularly polarized antenna. It should be noted that such high gain, directional antennas also reduce the delay spread in severe multipath environments by rejecting multipath components arriving from outside the main beam of the antenna. In one embodiment, the user station 102 employs a halfwave dipole antenna which is linearly polarized and provides a gain of 2 dB with an omnidirectional pattern perpendicular to the antenna axis. At a nominal frequency of 1900 MHz, a half wavelength is approximately 3 inches, which fits well within a handset envelope. MESSAGE TYPES AND PROTOCOL Figure 3 shows message types and a protocol which uses those message types. In a preferred embodiment, messages (base transmissions 204 and user transmissions 206) may be one of three types: a general poll message 301, a specific poll message 302, and an information message 303. When a message is transmitted by a user station 102, it is called a "response", e.g., a general poll response 304, a specific poll response 305, and an information response 306. User Station Initiation of a Link A user station 102 may "acquire" a base station 104 by a sequence of handshaking steps. At a general poll step 307, the base station 104 may transmit its general poll message 301 on an air channel 203 as part of a minor frame 202. The user station 102 receives the general poll message 301 and, if and only if it was received without error, transmits its general poll response 304 on the same air channel 203. The general poll message 301 comprises a base ID 308, which may be 32 bits long, which may be recorded by the user station 102. In like manner, the general poll response 304 comprises a user ID 309, which may be 32 bits long, which may be recorded by the base station 104. The base ID 308 may be used during handoff, as noted herein. Upon receiving a general poll response 304, at a specific poll step 310, the base station 104 may transmit a specific poll message 302, comprising the user ID 309 received by the base station 104 as part of the general poll response 304. The specific poll message 302 may be transmitted on the same air channel 203 as the general poll message 301, or may be transmitted on another air channel 203, so long as the user station 102 is able to find it. The user station 102 may monitor all air channels 203 for its specific user ID 309. The user station 102 receives the specific poll message 302 and, if and only if it was received without error and with the same user ID 309, transmits its specific poll response 305 on the same air channel 203. The specific poll response 305 comprises the same user ID 309 as the general poll response 304. In a preferred embodiment, however, the specific poll message 302 may be eliminated as redundant. The user station 102 may therefore follow the general poll response 304 with a specific poll response 305 on a selected air channel 203. This air channel 203 may be designated by the base station 104 in a part of the information field 209 of the general poll message 301, it may be designated by the user station 102 in a part of the information field 209 of the general poll response 304, or it may be selected by the user station 102 in response to an unoccupied air channel 203 (e.g., the user station 102 may seize an unoccupied air channel 203) . The latter of these three alternatives is presently preferred by the inventors. Upon receiving a specific poll response 305 comprising a user ID 309 which matches that of the general poll response 304, at a link-established step 311, the base station 104 may transmit an information message 303. At this point, the base station 104 and user station 102 have established a communication link 312 on a designated air channel 203, typically the air channel 203 originally polled by the base station 104, but possibly a different air channel 203. The base station 104 may couple a telephone line to that air channel 203, and the user station 102 may begin normal operation on a telephone network (e.g., the user station 102 may receive a dial tone, dial a number, make a telephone connection, and perform other telephone operations) . The base station 104 and user station 102 may exchange information messages 303 and information responses 306, until the communication link 312 is voluntarily terminated, until faulty communication prompts the user station 102 to re-acquire the base station 104, or until handoff of the user station 102 to another base station 104. Should more than one user station 102 respond to a general poll message 301 in the same minor frame 202, the base station 104 may advertently fail to respond. The lack of response from the base station 104 signals the involved user stations 102 to back off for a calculated time interval before attempting to acquire the same base station 104 using the general poll message 301 and general poll response 304 protocol. The back-off time may be based upon the user ID 309, and therefore each user station 102 will back off for a different length of time to prevent future collisions. In one embodiment, the general poll message is sent by a base station 104 on one or more currently unoccupied air channels 203. Originally, at power-up of the base station 104, the base transmission 204 for all of the air channels 203 may therefore contain the general poll message 301. Base Station Initiation of a Link When an incoming telephone call is received at a base station 104, at an incoming-call step 313, the base station 104 transmits a specific poll message 302 with the user ID 309 of the indicated recipient user station 102 (skipping the general poll message 301 and the general poll response 304) on an available air channel 203. Each user station 102 listens for the specific poll message 302 repeatedly on each air channel 203 so as to receive the specific poll message 302 within a predetermined time after it is transmitted. Thus each user station 102 may periodically receive each air channel 203 in sequence so as to listen for the specific poll message 302. When the specific poll message 302 is received, the user station 102 compares the user ID 309 in the message with its own user ID, and if they match, continues with the link- established step 311. The base station 104 may thus establish a communication link 312 with any user station 102 within communication range. Link Expansion and Reduction The data transmission rate between a base station 104 and a user station 102 may be expanded or contracted over the duration of the communication link. In one embodiment, the base station 104 increases the data transmission rate by transmitting multiple information messages 303 to the user station 102 during a major frame 201, essentially allocating multiple minor frames 202 to a single user station 102. These higher data rates, also known as "super rates", are implemented by means of a targeted information message 303. In a targeted information message 303, the base station 104 may transmit the user nickname 212 in the D field 208, along with information to be transmitted to the designated user station 102 in the B field 209. When the user station 102 detects the user nickname 212 assigned to it, it receives the targeted information message 303. In a preferred embodiment, the user nickname 212 may be transmitted by the base station 104 to the user station 102 in the specific poll message 302. In an embodiment where the specific poll message 302 has been eliminated as redundant, the user nickname 212 may be transmitted by the base station 104 to the user station 102 bit-serially in a designated bit of the header field 207. Because the data transmission rate is related to the number of minor frames 202 allocated to a specific user station 102, the data transmission rate increases in steps of, for example, 8 Kbps. It is contemplated that up to the full bandwidth of the base station 104 -- that is, up to all 32 full duplex slots or 256 Kbps (full duplex) -- may be assigned to a single user station 102. The invention also provides in another aspect data rates lower than the basic rate (i.e., less than one minor frame 202 per major frame 201 or less than 8 Kbps) . The lower data rate is accomplished by skipping major frames 201 on a periodic basis. Thus, data rates such as 4 Kbps, 2 Kbps, and so on can be provided. In one embodiment, up to 24 consecutive major frames 201 may be skipped, providing a minimum data rate of 320 bps efficiently (i.e., without using rate adaptation) . Intermediate rates or even lower rates may be obtained by using rate adaptation. The capability of providing variable data rates on demand, including availability of an asymmetric mode in a given minor frame 202 described earlier, provides an efficient and flexible data conduit for a wide array of data, video, multi-media and broadcast applications. For example, each minor frame 202 can be configured with the majority of the minor frame 202 duration allocated to either the base transmission 204 or the user transmission 206, or can be configured with a symmetric distribution in which half of the minor frame 202 duration is allocated to both the base transmission 204 and the user transmission 206. Typically, voice traffic utilizes a symmetric distribution as either end of the link may send voice traffic. In a data exchange, however, more data is typically sent in one direction and less in the other. For instance, if fax data is being sent to a user station 102, then a higher data rate for the base transmission 204 would be advantageous and is supportable with the described configuration. For even higher data rate applications, a particular base station 104 or user station 102 may be assigned multiple minor frames 202 within a single major frame 201. These high data rate modes can support, for example, enhanced voice quality, video data or broadcast data applications. Handoff and Network Maintenance Once a base station 104 and user station 102 have established a communication link 312, during the link- established step 311 the user station 102 may receive all information messages 303 and transmit all information responses 306 on the same air channel 203 or on specified multiple air channels 203. This arrangement leaves the remainder of the major frame 201 free for other activities. In a preferred embodiment, one such activity is to interrogate other base stations 104 and maintain network information such as link quality and channel availability at nearby base stations 104 in order to facilitate handoffs from one base station 104 to another base station 104. In a preferred embodiment, base stations 104 transmit network information as part of the general poll message 301 and the specific poll message 302, in a channel utilization field 314 or otherwise. The network information may include, for example, the identity of nearby base stations, the identity or relative amount of free channels at a particular nearby base stations and/or at the current base station, link quality for nearby base stations and/or the current base station, and frequencies and spread spectrum code sets used by the nearby base stations. At a network-maintenance step 315, the user station 102 may listen on one or more different air channels 203, other than the one(s) currently being used by the user station 102, for the general poll message 301 and the specific poll message 302 from nearby base stations 104. The user station 102 continues to communicate on its designated air channel (s) 203 with its current base station 104 and responds as necessary to information messages 303 from that base station 104. However, unless a handoff procedure is initiated as described below, the user station 102 does not transmit in response to other nearby base stations 104 and therefore does not occupy air channels 203 of those base stations 104. It is contemplated that the system may perform either a "make before break" handoff for seamless, undetectable handoffs, or a "break before make" handoff in emergency situations where all communications with a base station 104 are lost prior to a new connection being established. In a "make before break" handoff, if the communication link 312 between the base station 104 and the user station 102 is too faulty, then the user station 102 may acquire one of the nearby base stations 104 in like manner as it acquired its current base station 104. Such a handoff procedure may be further explained with reference to Fig. 1-3. In Fig. 1-3, it is assumed that a user station 102 presently in communication with a current or original base station 405 has determined it to be desirable to transfer communication to a different base station 104, such as a first terminal base station 410 coupled to a common base station controller 407, or a second terminal base station 406 coupled to a different base station controller 408. A handoff to the first terminal base station 410 will be termed an "intra- cluster" handoff, while a handoff to the second terminal base station 406 will be termed an "inter-cluster" handoff. The following explanation will focus on an intra-cluster handoff to the first terminal base station 410, but many of the steps are the same as with an inter-cluster handoff, and the salient differences between an intra-cluster and inter-cluster handoff will be noted as necessary. In general, when the user station 102 determines that a handoff is appropriate, the user station 102 acquires an air channel on the new or terminal base station 410 and notifies the base station controller 407 coupled to the current base station 405 to switch the incoming phone line from the current base station 405 to the new base station 410. More specifically, a handoff procedure may be initiated when the received signal level at a user station 102 falls below an acceptable level. While the user station 102 receives bearer traffic from its originating base station 405, the user station 102 measures the received signal quality (e.g., RSSI) of its communication link 312. The received signal quality value, together with measurements of the current frame error rate and type of errors, determines the overall link quality. If the overall link quality drops below a first threshold (the measurement threshold) , the user station 102 begins searching for available air channels 203 (i.e., time slots), first from the originating base station 104, and then (using appropriate frequencies and spread spectrum codes) from neighboring base stations 104 of adjacent or nearby cells 103. The user station 102, as mentioned, preferably has obtained information regarding the identities of neighboring base stations 104 (including spread spectrum code set and frequency information) from the originating base station 405 by downloading the information to the user station 102 during traffic mode or otherwise. As the user station 102 scans potential new air channels 203 using the appropriate frequency and/or spread spectrum code set, the user station 102 measures and records the received signal quality. The user station 102 reads a field carried in all base transmissions 204 which describes the current time slot utilization of the base station 104. The user station 102 uses these two pieces of information to form a figure of merit for the new base station signals, including the originating base station 405, and then sorts the base stations 104 by figure of merit. This procedure allows the user station 102 to evaluate the quality of available air channels 203 for both the originating base station 405 and other nearby base stations 104. If an air channel 203 (or air channels 203, as the case may be) for the originating base station 405 has better quality than that of any base station 104 in adjacent or nearby cells 103, a time slot interchange (TSI) handoff is considered, which maintains the link to the originating base station 405 on a different air channel 203 than was previously being used by the user station 102. If the link quality drops below a second threshold level, then the user station 102 (during a no-bearer time slot) requests a handoff from the base station 104 with the highest figure of merit (which could be a TSI handoff with the originating base station 405) . The handoff is requested by seizing an air channel 203, sending a handoff message request, and waiting for an acknowledgment from the new base station 410. The handoff signaling message contains a description of the circuit connecting the originating base station 405 to the network, which description was passed to the user station 102 at call establishment time. If the new base station 104 accepts the handoff request (by acknowledging) , then the new base station 104 becomes the terminal base station 410. Note that the user station 102 maintains its original air channel 203 connection with the originating base station 405 during this handoff procedure, at least until a new air channel 203 is acquired. To complete an intra-cluster handoff, at a handoff step 316 the user station 102 transmits to the new base station 410 the base ID 308 of the old base station 405. The old base station 405 and new base station 410 may then transfer the handling of any telephone call in progress. More specifically, the terminal base station 410 sends a message in the form of a "note" (as previously described) to its base station controller 407, requesting that the original circuit be switched from the originating base station 405 to the terminal base station 410. If the base station controller 407 is common to both the originating base station 405 and terminal base station 410, the handoff is termed an intra-cluster event, and the base station controller 407 bridges the circuit from the originating base station 405 to the terminal base station 410. The base station controller 407 then sends a circuit-switch-complete note to the originating base station 405 and also to the terminating base station 410, commanding the latter to continue the handoff process. In the case of an inter-cluster handoff, the base station controller 408 is not common to both the originating base stations 104 and the terminal base station 406. For these types of handoffs, as with intra-cluster handoffs, the terminal base station 406 sends a message in the form of a note to its base station controller 408, requesting that the original circuit be switched from the originating base station 405 to the terminal base station 406. The base station controller 408 translates the handoff note into the signaling language of the network host 409 (e.g, a PCSC) and requests an inter-cluster handoff at the network level. In some network architectures, the host network 409 cannot accept a handoff request from a terminating base station controller 408, in which case an intermediate step is taken. The handoff request may be sent via an X.25 link to the base station controller 407 connected to the originating base station 405. The originating base station controller 407 then translates the handoff request and relays it to the network host 409. The network host 409 acknowledges the circuit switch to the originating base station controller 407, which then sends a circuit-switch-complete note to the terminal base station 406. When the terminal base station 406 receives the circuit-switch-complete note, the terminal base station 406 begins paging the user station 102 with a specific poll, and the originating base station 405 signals the user station 102 to transfer to the terminal base station 406. When the user station 102 receives the signal to transfer to the terminal base station 406, or if the link is lost during the handoff process, the user station 102 switches to the terminal base station 406 and searches for a specific poll message 302. When the user station 102 receives the specific poll message 302, the user station 102 completes the connection to the terminal base station 406, and the handoff procedure is finished. Should the link between the user station 102 and the originating base station 405 or terminating base station 406 (or 410) be completely broken at any time, the user station 102 will search for the highest quality base station 104 on its list of potential handoffs, and attempt a handoff without communication with its previous base station 405. This capability allows the user station 102 to recover from situations in which the original link was broken before the normal handoff procedure could be completed. An intra-cluster handoff, including re-establishment of bearer channel traffic, may ordinarily take from less than 10 milliseconds to as much as 40 milliseconds. Since under normal circumstances the handoff time is less than one polling loop interval, bearer packets will continue to the user station 102 with no interruption. Inter-cluster handoff times are partially dependent upon the delays inherent in the host network 409 and are not always easily predictable. A unique aspect of the above described "mobile directed" or "mobile centric" handoff technique is that the user station 102 makes the decision to handoff between cells and directs the base station controller or network to make a line switch once an alternative base station 104 is acquired. This approach is quite different from a "network directed" or "network centric" approach such as used in systems such as AMPS, IS-54 cellular, and GSM. The mobile centric approach also differs significantly from so-called "Mobile Assisted Handoff" (MAHO) in which the network collects information and directs all or most of the handoff functions, thereby utilizing the user station 102 primarily as an additional One problem that may occur during handoff is a situation in which there are repeated attempts to switch between two or more base stations 104 during times, for example, when the measured quality of the received signals from two competing base stations 104 is very close, or when environmental effects cause rapidly changing deviations in the relative measured signal quality of the signals from competing base stations 104. The repeated switching between competing base stations 104 may be referred to as "thrashing" and may have the undesirable effect of consuming excess capacity from the network. In order to reduce the effect of thrashing, hysteresis measurements from multiple base stations 104 may be maintained by the user station 102 so that a handoff does not occur until the quality of the signal from a new base station 104 exceeds the quality of the signal of the original base station 405 by a predetermined margin. In such a manner, important air channel resources in the network may be preserved. In rare instances, two user stations 102 on the same minor frame 202 in different cells 103 but on the same frequency may encounter propagation characteristics in which the spatial and code separation are insufficient to prevent bit errors, thus causing the user stations 102 to begin experiencing degradation of their RF links. In such cases, a time slot interchange (TSI) may be performed wherein one or both of the conflicting user stations 102 are assigned different minor frames 202 within their respective major frames 201 to eliminate further collisions. Such a procedure may be viewed as the time domain equivalent of dynamic channel allocation as the system either assigns an unoccupied air channel 203 to the user station 102 or switches the user station's 102 minor frame 202 with that of another user station 102 in the same cell 103 which is geographically removed from the interference. Security and Error Handling The protocol of the invention protects communications against errors in several ways: protocol handshaking, user ID verification and reverification, and synchronization by reacquiring the base station. Handshaking, verification and synchronization protect both the base station 104 and the user station 102 from receiving telephone calls in progress on any other air channels 203. Handshaking provided by the general poll step 307 and the specific poll step 310 requires that the proper message having the proper header be transmitted and received, and in the proper sequence. In each message, the header field 207 (sixteen bits) is protected by a CRC code 211 (four bits) ; an error in the header field 207 or in the CRC code 211 indicates an error and will cause the protocol to restart handshaking with the general poll step 307. The user ID is verified twice, once by the base station 104 and once by the user station 102. In the general poll message 301 and specific poll message 302, the user ID 309 is protected by a CRC code 211 (sixteen bits) , in like manner as the CRC code 211 for the header field 207. An error in the user ID 309 or in the CRC code 211 will cause the protocol to restart handshaking with the general poll step 307. At the link-established step 311, the base station 104 and the user station 102 are protected against drift and/or desynchronization, even when transmission or reception are interrupted. When a threshold for an error rate is exceeded, the base station 104 and user station 102 each independently stop sending data in information messages 303 and information responses 306, and return to the specific poll step 310 for resynchronization. In an embodiment where the specific poll message has been eliminated as redundant, the base station 104 and the user station 102 may determine resynchronization by means of a designated bit in the header field 207. Each base station 104 provides the basic TDMA loop timing structure for its cell or sector. As previously noted, a synchronization preamble in the form a control pulse 215 or power control command is transmitted at the beginning of each minor frame 202 by the user station 102 and the base station 104, respectively. When the appropriate preamble, consisting of a code sequence 48 chips in length, is received, a digital correlator (i.e., a matched filter) attuned to the specific preamble generates an internal synchronization pulse which may be very brief (e.g., two chips in duration, or 400 nanoseconds) . The internal synchronization pulse may then be used to synchronize the start of M-ary symbol detection process. Excerpts of JTC Submissions The immediately following sections contain excerpts of the design specifications and technical standards submissions which were submitted to the Joint Technical Committee on Wireless Access in the United States. These sections were included in Appendix A, B, and C in U.S. Application Nos. 08/215,306 and 08/284,053 from which priority is claimed, and have been edited to reduce redundancies. Candidate Air Interface Solution Presentation 1. Introd u ction 1.1 Preface Omnipoint has developed an innovative spread spectrum RF access technology, communications protocol, and architecture for controlling Base Station resources and high speed handoff. Omnipoint's PCS System can be integrated into networks using AIN, GSM, IS-— 1 and ATM based architectures. Omnipoint's PCS System provides full functionality PCS - i.e. full coverage, full mobility, and high speed data up to 256 Kbps full duplex or 5 12 Kbps half duplex. Moreover, a single handset and Common Air Interface can be used in all three wireless markets: public, business and residential in either licensed or unlicensed frequency bands. Perhaps most importantly, Omnipoint's approach oϊ^ers significant, sustainable in frastructu re cost reductions and thus provides the PCS operator with long term economic advan tages over alternative approaches. The Omnipoint system uses a proprietary combination of CDMA, TDMA, and FDMA for separation of users and cells. In general, users are separated within a cell by a proprietary spread spectrum TDMA technology and cells are separated by FDMA as well as CDMA. The spreading codes are also used to achieve significantly higher data rates and thus more TDMA users per RF channel than generally thought possible with traditional TDMA systems without requiring the use of expensive and power consumptive equalizers. These technologies coupled with the use of Time Slot Interchange (TSI), directional antennas, and a unique mobile-centric approach to managing RF resources and handoff provide for extremely low cost and efficient provisioning of PCS. Omnipoint has implemented experimental prototypes of this technology into pocket phones and palm-sized data devices, as well as in miniaturized Base Stations. Omnipoint systems can be configured to provide outdoor cell radii of 0.3 to 2.2 miles in urban areas, 1 to 5 miles in suburban areas, and over 8 miles in more open areas (with proper antennae configurations and some reduction in the number of time slots). ' To date Omnipoint Base Stations have been tested in low density urban areas with up to 3 mile diameter cells with handsets operating at mobi le speeds. Hand-off has been performed at 65 miles per hour in both large cel ls and small cells (for example, 1000 feet). When used indoors, Omnipoint's private systems can offer the features, data rates, and voice quality required to serve both business and residential users and thus differentiate PCS from cel lular and other services which can only offer compressed voice and very low speed data. Omnipoint has developed its system specifically to serve both outside and indoor environments and has conducted success ful experiments testing its indoor PCS systems in more than 100 buildings of virtually every size and type of construction imaginable. Further, to understand the needs of indoor users, Omnipoint has interviewed 1 SO of the Fortune 1000 telecommunications managers who purchase equipment and found that 1 ) none of them were willing to pay for air time charges while wireless on their own premises and 2) they all insisted on owning their own Base Station equipment and having it functionally integrated with their PBXs. This virtually requires the use of unlicensed frequencies in many locations if large market penetrations are to be achieved. Omnipoint's system is unique in using the same CAI to meet this private premises need in 'The CAI can be adjusted to accommoda te d ifferent cell sizes as required by the TDD guard rime. The specific implementation defined in this submission uses the basic 32 slot, S bps fu ll duplex informa tion rate which has guard rime for operation out to 1.5 miles (3 mile diameters). To operate a t 3 mile radii (6 mile diameters) for example requires a reducrion to 30 slots. Ten miles radii (20 mile diameters) can be supported by reducing the number of 8 kbps full duplex slots to 25. Since, by definition large cell rad ii will only be used where capacity is not an issue, this small reducrion in capacity will have minimal impact. For example, going from 1.5 miles to 10 miles increases the area served by 4300% with only ?. 22% reduction in capacity per RF channel. either unlicensed or licensed frequencies while allowing customers to use the same handsets in the outdoor, public, mobile environment. 1.3.4 Wireline q ua lity is an essen tial option fo r PCS s u bscribers. This goal is a differentiating attribute of PCS over existing cellular and is important particularly for in-building applications. Omnipoint provides the ability for a subscriber t use 32-24 Kbps ADPCM if desired for wireline quality voice or 8 Kbps (and later 4 Kbps) for outdoor mobile environments. 1.3.5 Va riable Ban dwidth on Deman d. By 1996, multimedia and digitized video applications (especially video phones) will create significant market opportunities for differentiated PCS services. Omnipoint's system can provide 64 Kbps as well as multiples of 64 Kbps (up to 256 Kbps full duplex and 5 12 Kbps simplex) for data, video, mul timedia, and broadcast applications. Additionally, the user can vary the data rate, requesting only the minimal rate necessary for the application. Omnipoint's system supports extremely fast circuit seizing and releas (50ms, and typically less than 10ms) allowing for efficient provision of bursty packet dat as well as slow speed data. Note: The overall architecture, techniques, and specific implementations described in this submission are the subject of multiple pending (and in some cases awarded) patents. Certain questions in the JTC template would involve disclosing particularly sensitive proprietary information and thus are not answered and specifically noted as "proprietary" This does not, however, imply that the remaining portions of this document are not proprietary. 1 Control traffic The control traffic provides for link specific data messaging or call control information. Control traffic can be provided through a number of logical methods as detailed below, includin 'g_> a customer "D" channel associated with each time slot. Notes Omnipoint implements network interfaces based on Q.93 1 ISDN and SS7 to the necessary network components. In general, the Omnipoint system is designed around an object-based software architecture which al lows for flexibility in interconnection to a number of network infrastructures. The system uses messages based on ISDN messages which are called "Notes" (so as not to confuse them with the ISDN specific protocol itself) for passing necessary information among components within the system. Messages from the network are converted by the system into Omnipoint "Notes" for efficient operation within the Omnipoint subsystems. This approach provides the PCS operator with flexibility to deploy whatever network infrastructure meets the appropriate business goals and service descriptions desired. 2. Minim um Service Capa bilities This section contains the list of minimum service capabilities required of a PCS system. For each item, the Omnipoint system indicates which of these features will be supported, immediately (I) - in the course of system evolution (E) not planned (N) 2. 1 Min im u m Featu res - JTC(AIR)/93.05.13- 133R1 Omnipoint's access system is being integrated into various types of Network Architectures such as AIN, Americanized GSM, IS-4 1 , and ATM-based systems. The availability of a specific feature/service is thus determined by when the PCSC network architecture supports it. Below is a list of feature/service availability for two of the PCSC architectures as proposed by the vendors of those networks: * Items marked "E" requirε PCSC network support which does not yet exist. For example, in the case of AIN, "I" means AIN 0.0, and "E * -2" reflects the specification for AIN 0.2. The signaling path across the Omnipoint air interface for provision of thesε sεrvicεs is currently supported. 2.1 Minim u m Featu res - JTC(AIR)/93.09.22-365 44 * Items marked "E" require PCSC network support which does not yet exist. For εxamplε, in thε casε of AIN, "I" mεans AfN 0.0, and "E* -2" reflects thε speci fication for AIN 0.2. The signaling path across the Omnipoint air interfacε for provision of thεse services is currently supported. i -> Min im u m Voice Services * Items marked "E" requirε PCSC network support which does not yet exist. For examplε, in thε case of AfN, "I" means AIN 0.0, and "E*-2" reflects the specification for AIN 0.2. The signaling path across the Omnipoint air interfacε for provision of these sεrvicεs is currently supported. i i Minim u m Vo ice Servi ces - Text The Omnipoint system provides land line quality voice services to the end user for wireless access to the network. Thε system is designed to provide transparent operation for the user to network functionality including DTMF tones for interactive services, music on hold, and the provision of active call features to remain intact even after a handoff between cell sites. Higher levels of voice quality can be provided by thε systεm in incrεmεnts of 8 Kbps (and in thε futurε, at even lower vocoder rates) without any change to the Base Stations or the CAI. Thus, i f the user desires 32 Kbps, for instance, this class of service is made known to thε system at call set-up time and CCITT G.726 standard ADPCM is executed. CCITT G.726 is fully supported. CCITT G.726 64 Kbps PCM is also supported as well as a propriεtary 8 Kbps CELP algorithm. Lower channel rates, such as 4 Kbps, are also supported to allow for future upgrades without any changes to thε CAI or the Base Station hardware. Under some conditions Voice Activity Detεction (V.AD) "half duplex" can bε supportεd, allowing up to twice thε number of voice users in a particular RF channεl. Voicε services provided by Omnipoint will be available to end users in both mobile and non-mobile environmεnts. Sεε Section 4.3.1 2.3 Mini m u m Da ta Services " Items marked "E" rεquire network support which does not yεt εxist. Thε signaling path across the air interfacε for provision of thεsε sεrvicεs is currεntly supported. 2.3 Min i m u m Da ta Services - Text 2.3.1 . Inter working with the PSTN Da ta S ervices A provision is made for user accessible, inband signaling by utilizing 'flash' and DTMT signaling conventions. Additionally, data transmission over thε Omnipoint CAI is supported by both dedicated data channel methods, at up to 256 Kbps full duplex described elsewhεre and conventional inband support for data modems as follows: ( 1 ) Voice band data performance up to 2400 bit/s using (for example) modems conforming to recommendation V.2 1 , V.22 bis, V.23, and V.26 ter, will not be subject to significant degradation over 32 Kbps ADPCM links provided the numbers of those l inks do not excεed the limits of recommendation G. l 13. (2) Voice band data performancε at 4800 bit/s using (for εxamplε) modεms conforming to rεcommεndation V.27 bis, can be accommodated with 32 Kbps ADPCM but will bε subjεct to additional degradation above that expected from standard 64 Kbps PCM links. (3) Voice band data at speeds up to 12,000 bit/s can be accommodated by 40 Kbps ADPCM. Thε pεrformancε of V.33 modems operating at 14,400 bit/s over 40 Kbps is under study. (4) No dεgradation is e pεctεd when using 40 Kbps ADPCM with Group II or Group II! facsimile apparatus according to Recommendations T.3 or T.4 rates up to 1 2,000 bit/s. Performance of group III facsimile when using 40 Kbps ADPCM at 14,400 bit/s is under study. No serious degradation is expected whεn using 32 Kbps ADPCM with Group II facsi ilε apparatus according to Recommendations T.3 or T.4 at rates up to 12,000 bit/s. (5) Multiples of S Kbps, 56/64 Kbps, ISDN, etc., up to 256 Kbps full duplex and 5 12 Kbps can be supported. 2.3.2. In ter wo rking t> with Circuit Switched D igital Data Services Circuit mode digital data is supported across thε air interfacε. As noted above, all ISDN data servicεs from 8 Kbps up to and including 256 Kbps ful duolεx arε supportεd in increments of 8 Kbps. Sub 8 Kbps rates to 320 bits/s are supported in 160 bits/s increments. Lower rates or rates which are not multiples of the o given incremεnts are supported bv rate adaptation. All half duplex ISDN services from 8 Kbps up to and including 5 12 Kbps in increments of 8 Kbps are supported. Sub 8 Kbps rates to 320 bits/s are supported in 160 bits/s increments. Lower rates or rates which are not multiples of the given increments are supported by rate adaptation. Thε specific Inter working Function (IWF) used is dependent upon thε network or circuit switch service chosen in a particular network. 2.3.3. In ter wo rking with Pa cket Switch ed Da ta Services The system providεs full duplεx synchronous data transfer over-the-air in dynamically variable data rates, sεε above "Inter working with Circuit Switched Digital Services" . Thε terminal application may use a data channel to communicate with a Packet Assembler/Disassεmblεr (PAD) and/or IWF using thεsε facilities. X.25 packet data is supported. During times of low data rates thε terminal will rεduce its ovεr-thε-air bandwidth requirement accordingly. 2.3.4. Contention-Based Sha red Access Mechanism Thε systεm providεs a very fast circuit seizing protocol. Since contention for a channel can occur at this point it is resolved with an IEEE S02.3-Iike backoff procedure. Since the overhεad for channel sεizing and release is very low (sub 50 ms and typical ly, sub 10 ms), a transaction basεd application will acquire a channel, build a circuit to thε appropriate IWF module, send its data, and release the channel very quickly. Very low data rate applications will have a very low channel access duty cycle. 2.3.5 Specialized Data Applications Since the Omnipoint System is designed as an "accεss and transport mechanism," it will be able to support many different specialized data applications as noted above. 2.3.6 Data Quality Error correction in bεnrer data is optional in thε systεm. The end user has the option of activating Automatic Re-transmission Query (ARQ) error correction or leaving error correction disabled, for example, for use with digitized compressed video. The ARQ mechanism uses a data window of two frames. When a frame is determined to be corrupted, via the standard ISDN 16 bit Frame Check Word (FCW) , the receiving unit signals the transmitter for a re-transmission. Thε number of re-iransmission attempts is a service provider or subscriber parameter. Thε maximum uncorrectεd frame error rate of thε system is 10 ~ ~ at threshold receiver sensitivity (See Section 4.6. 1 ). After applying ARQ correction the frame error rate at threshold is: 1 0-2 /(2 l 6 _ ] ) which is 1 .53 X I O" 7 undetected frame errors. If it takes two retries to receivε thε data correctly, the latency of 8 Kbps data corrected by an n=2 ARQ is SO ms. 2.3.7 Da ta servi ce in tegrity th ro ugh h a n dover Data rate and integrity are maintained before and after handover. Since data may be lost during the handover, the system uses higher level protocols, i.e. not thε CAI, to correct the loss of frames. A typical handover delay, including switch time, for an intra Base Station Controller handover is less than 10 ms. Thε maximum handover time, assuming that communication with the Terminal Base is error frεe, is approximately ύ 0 ms. The system supports an out-of-band logical D channel in conjunction with spεεch or data. This channel supports acknowledged ISDN D channel sεrvicεs at a ratε of 400 bit s with no intεrfεrence to the bearεr channεl. In addition, inband signaling, εithεr half or full duplex, can bε usεd for largεr mεssagεs. Inband signaling will temporarily displace thε user level bearεr chaπnεl traffic. Vεry high spεεd paging may be sεnt via thε unacknowledged data broadcast facility. Using this facility, data at up to 5 12 Kbps can be sent over the air interface. This modε doεs not address specific units. It is assumed that an MS residεnt application will intεrprεt thε format of data in thε broadcast format. 2.4 Privacy an d Au th en tication The Omnipoint system will support authentication (the process of verifying the identity a user, terminal and service provider) and validation (the process of veri fying that a user and/or terminal is authorized to access services). The authentication and validation process will permit the system operator to separate fraudulent wireless devices, unauthorized users, and authorized users before service is granted. This prevention can extend to both speech as well as data services. Thε Omnipoint systεm will support privacy of signaling and usεr information (e.g., speech and data) and will maintain the privacy of the user identity and location. The Omnipoint system can allow protection against unauthorized usε by requiring the usεr to enter a PIN. The portable will default to requesting thε user for thε PIN upon powering up the device. This default can bε d isabled through an appropriate control function. Omnipoint's system can support thε use of SIMs. The final methodology for supporting privacy and authεntication in the Omnipoint syste will be detεrminεd by industry efforts, specifically from the Joint Experts Mεεtiπg on Privacy and Authentication or as otherwise detεrminεd by the PCS operators. 2.5 Featu re Invocatio n (User Interfa ce) Thε air interface facilitates invocation of user functions in a consistεnt fashion. Thε MS providεs for feature invocation by keypad digit entry, function key and dynamic menu. Omnipoint supports futurε usεr fεaturε activation standardization at thε keyboard/display level. The Air Interface Signaling method used by the systεm for fεaturε invocation is based upon ISDN Q.93 l/.ANSI Tl .607 signaling. In order to reduce thε bandwidth required for this signaling and to allow compatibility with the propertiεs of an RF link, an abbreviated format is used in the over-the-air messaging. Thesε mεssages are converted to the appropriate ISDN messages at a higher level in the system architecture. 2.6 Sim u ltaneous Voice An d Data Simultaneous voice and data are supported by the air interfacε. Data and voicε may bε mixed to a total full duplex rate of 256 Kbps or 5 12 Kbps simplex in steps of 8 Kbps. This allows, for examplε, toll quality voice, 32 Kbps ADPCM, and simultaneously up to 224 Kbps of full duplex data. Or, for example, thε simultanεous provision of a 128 Kbps vidεo link, a 64 Kbps ISDN B channel transporting multimedia images to computers, and eight full duplex S Kbps voice conversations. In addition, low rate data can be sent simultaneously over the D channel without requiring additional time slots. 2.7 Automatic Speech Codec Identifica tion Selection of thε vocoder algorithm is madε by thε call originating party at call setup time. This is done either by automatically accessing thε user's HLR data base for the default selection and selecting the vocoders at each end of the link or alternatively, the subscriber can select vocoder options at call origination. 2.S Portable Term inal Req u irements 2.5.1 Dialing Thε Omnipoint Terminal can transmit dialed digits using logic recognizing thε North American Dialing Plan, eliminating thε rεquirεmεnt for a traditional "Send" button to dial digits in basic operations. Alternatively, the Send button can bε usεd. 2.8.2 DTMF DTMF signaling out-of-band across thε air interface is supported. The DTMF tones will bε sent by network conversion of the messages into tones by a higher order architectural elεmεnt. DTMF tones will not bε carriεd by the audio bearer channel. DTMF tone will be transported back to the MS. 2.5.3 Switchhook flash The Omnipoint terminal has a "flash" burton which transmits signaling across the air interface out-of-band to indicate to the network that a switchhook flash has occurred. Thε actual hook flash is generated by a higher order architectural elεmεnt. 2.5.4 Home/Roa m indication The Omnipoint terminal will have an indicator displaying either a "home" registration or a visitor "roam" registration. This indicator will bε activated by service provider identification that is associated with thε general poll frame from the Base Station. 51 2.9 Possible Future Services 2.9 Possi ble Fu tu re Services - Text 2.9.1 Low a n d mediu m speed video Full duplεx vidεo up to 256 Kbps in steps of 8 Kbps, half duplex video of up to 5 12 Kbps in steps of 8 Kbps and 8 Kbps audio with simultanεous vidεo up to 248 Kbps are supported. JPEG and MPEG standards are supported. 2.9.2 Digital data up to 144 Kbps All ISDN data servicεs from 8 Kbps up to and including 256 Kbps full duplεx arε supported in incremεnts of 8 Kbps. Sub 8 Kbps ratεs to 320 bits/s arε supportεd in 160 bits/s increments. Lower rates or rates which are not multiples of the given increments are supported by rate adaptation. All half duplex ISDN data servicεs from 8 Kbps up to and including 512 Kbps in 8 Kbps incrεmεnts are supportεd. Sub 8 Kbps ratεs to 320 bits/s are supported in 160 bits/s increments. Lower rates or rates which arε not multiples of the given increments are supported by rate adaptation. Digital rates of 144 Kbps in the form of an ISDN BRI channel, that is 2 * 64 Kbps + I * 16 Kbps, arε supportεd. 52 2.9.3 Invocation of Intelligent Network Features The air interface can carry the Q.931/TI .607-iϊ e messaging necessary to invoke AIN functions. 2.9.4 Selection of wireless service providers on a per-call basis. Sεlεction of spεcific wirεlεss sεp.'icε provider or privatε network on a per call basis is supportεd by the CAI. Each sεrvicε providεr is identified by the Base Stations during the acquisition phasε of a call. Actual accεss to thε provider is controlled by the subscribers profile and by SIM information at the terminal. ->. System Description Template Description of Template Items - Class I -Not applicable to Omnipoint system because clock stability (transm it and receive) leads to 1 2.5 nsec maximum dri ft over 625 μsec frame time corresponding to 0.06 chip drift. J Thε Omn ipoint data transm ission system is organized utilizing TDD and TDMA. The base provides the basic loop tim ing structure and, to maxim ize capacity, must be synchron ized such that all base Stations within the same geographic vicinity begin transm ission at the same time with 6 μscc. tolerance. Omnipoint utilizes GPS at the base station controller (and optionally at the base station) for the generation of thε primary timing marker. This marker is captured at the base station controller every second en the second UTC and transmitted down the back hau l lines to the aπached bases. This capability also al lows the OA&M system to temporal ly turn o ff absolute CA I time slots which may have been interfering with a neighboring base air slot. ''The primary data tim ing standard in a digital backhaul system .such as ,T 1 or ISDN BRI or PRl is the PSTN. In order to prevent data precession into overrun or under run, the base station control ler and base station must be data locked to the PSTN. r End Acoust ic : The Omnipoint mobile station successfu l ly uses mechanical isolat ion rather than electronic echo cancel lation techniques to prevent acoustic feedback. Near End Electric : The Omnipoint system utilizes DSP based digital echo cancellation techniques in the transcoder on the base station controller. Th is algorithm has a short term length of up to 5.5 msec. Fa r End Electric : The Om nipoint system utilizes DS P based digital echo cancel lation techniques in the transcoder on the base station control ler. Th is a lgorithm has an adaptive long term length of up to 5.5 msec. 3.2 Description of Templa te Items - Class II "Directional gain antennas arc used to mitigate delay spread as well as other multipath effects in larger cel l con figurations. ^ System frequency error tolerance is much greater than Doppler shift produced by system dynamics. 56 4. Sys tem Des criptio n Q u estion na ire 4.1 Genera l System Iss ues 4.1.1. Arch itecture The Omnipoint system is composed of thε fol lowing four network hierarchical elεmεnts; Mobile Station (MS), Base Station (BS), Base Station Controllεr (BSC), and a Personal Communications Switching Center (PCSC). Mobile Station (MS) Thε Mobile Station (MS) is the subscriber terminal. It communicates with one Base Station (morε during handover) and is responsible for the fol lowing: Mobility Managemεnt. Unlikε most full mobility systεms, thε Omnipoint MS controls th handover actions of the systεm. It is rεsponsiblε for monitoring thε quality of thε ongoing bεarεr connεction with its currεπt Base Station as well as thε quality of signals receivεd from other nearby Base Stations/Cells. If the quality of the bearεr channel drops below an acceptable level the MS will initiate a handover to a bettεr BS. Thε MS is also rεsponsible for maintaining registration with its currεnt BS as well as directing thε BSC to make a switch of BS's as part of thε handovεr. Cnll Con trol. The MS is rεsponsiblε for initiating outgoing call rεquεsts and periodically monitoring for incoming call pages. Page monitoring is scheduled on duty cycle basis to reducε power consumption. Trnnsmission. The MS maintains the over-thε-air channεl from thε mobilε pεrspεctive. It performs all necessary timing, slot aggregation and error recovery. Authentication. The MS maintains thε subscriber secret key and performs the required calculations necessary to authenticate the device. Applications. The MS executes the appropriate downloadable user applications. The applications implement the short messaging service, broadcast messaging and data sεrvicεs. Additional usεr spεcific applications using ihε systεm data sεrvicεs may also bε downloaded and executed. Subscriber Interface, i hε MS implements the feature activating subscriber interface as well as the interface to specific downloaded applications in the MS. Base Station (BS) The Base Station (BS) is an intelligent dεvicε which controls the over the air signal and serves as Cell controller. It communicates with multiple MSs and a Base Station Control ler. It provides thε following functionality: Radio Resource Management. The 3S controls the over-thε-air slots of thε TDMA spread spεctrum transceiver. Thε BS allocatεs these slots based upon MS initial service rεquεsts, handover bandwidth demands, special service neεds and OA&M tεst and opεrational restrictions. In addition, thε BS is thε component which is charged with allocation of spεci fic slots, supεr-slots, and sub-slots to maintain thε requestεd bandwidth. Mobility Management. Thε BS responds to MS handovεr rεquεsts if rεsourcεs arε available. The BS assigns network and radio resources to thε MS and sends a rεquεst to thε Basε Station Controllεr to εxεcutε a handovεr switch. The BS also maintains rεgistrations with MSs within its Cell. This registration information is maintained in a stub or cache Visitor Location Register (VLR). Time Slot In terchange (TSI). This ήjnction allows a Mobile or a 3asε Station to changε thε opεrational time slot if interference is detected, taking advantage of statistical placement of Mobilε Stations in both thε original and rε-usεd cells. Thε system supports very quick TSI, within a single polling loop (i.e., less than 20 msec), as rεquirεd and available. Call Con trol. Thε BS interprεts thε over-the-air signaling traffic and translates this traffic from its concise form to an appropriate network indεpεndεnt format called Notes. These Notes have been dεsignεd to rεducε nεrwork latency and bandwidth while communicating succinct information to the higher elements in the network. Transmission. The BS is responsible for the allocation of network channels to their corresponding air slots. The BS controls these resources for both incoming and outgoing calls. Audio connections over network channels are maintained in their compressed form. In order to support a wide variety of bandwidths to the MSs, multiple network time slots may be assigned to a specific MS. The BS is also responsiblε for monitoring thε interference on the radio and adjusting its slot utilization to minimize this interfεrεnce. In addition, thε BS mεasurεs signal quality from its MSs and sεlεcts antεnnas for space diversity and polarization when appropriate, as wel l as controls thε MS power. uthen tication , i he Basε ^ Statio responds to Notes from thε B sε Station Con^ol '- t o Operations, Ad ministra tion a nd Ma in tenance. The Base station maintains accouπtim information for each connection in an accounting log. This information along with maintenance statistics arε trans ferred to thε Basε Station Controllεr and higher level entities via Notes. Notes are also usεd to block, unblock, and loopback-tεst network channels for maintenance purposes. Thε PCSC also provides OA&M. Base Station Controller (BSC) The Base Station Controller (BSC) is an intel ligent swi tch which controls and performs switching functions for a group of Basε Stations called a cluster. It communicates with multiple Base Stations, and a PCSC. Thε Base Station Controller functionality is: Mobility Management. The BSC interprεcs handovεr requests from its Base Stations. I f the handover rεquεst represents an intra cluster handover, i.e. between two Base Stations on the same BSC, the BSC switches all of the circuits associated with the MS from thε originating BS to thε tεrminating BS. If thε handovεr rεquest indicates that the originating BS is locatεd on some other BSC then the handovεr Note is translated into a form appropriate for the host PCSC and this form is forwarded to the host PCSC. Call Control. Thε BSC is rεsponsiblε for cluster location of the MSs. Registration information forwarded from a BS is recorded in a local stub Visitor Location Register (VLR) located in the BSC. This is used to locate the MS during alerting operations. Line resource requirements forwarded from the BS arε also held in this stub VLR. Furthermore, the BSC translates the commands and data contained in Notes passed to it by thε BS into signaling suitable for the host PCSC system. In this sense the BSC acts as a translator between thε Omnipoint system and thε host systεm. Transmission. Thε BSC is rεspoπsiblε for allocation and termination of the trunking circuits between the BSC and the host PCSC. The BSC is also responsible for thε transcoding of compressed audio to thε trunking format. Thε BSC furthεr serves as an Inter-Working-Function bεtweεn the Omnipoint data channelization format and othεr network formats. Operation, Adm inistration and Maintenance. The BSC stores accounting information delivered to it by the BSs. This information is translated into a form suitable for the host system and forwarded to the PCSC. In addition the BSC is responsible for blocking, unblocking and loop testing circuits upon request from the PCSC. Personal Communications Switching Center (PCSC) The PCSC is thε primary switch and thε interconnect to the PSTN. Thε Omnipoint system has been designed to connect to a variety of existing and proposed switch systems, including the AIN network, the Americanized version of GSM, IS-41 , and ATM-based networks. Thε operation of these systems is outsidε the scope of this response. Mobility Management. The PCSC providεs intεr clustεr and intεr PCSC handovεr capability. In addition thε PCSC providεs Hornε Location Registεr (HLR) and Visitor Location Rεgistεr (VLR) services. In this capacity the PCSC responds to its normal signaling mεssaging as provided by thε BSC translation function. Call Con trol. Thε fundamεntal opεrations nεcεssary for cal l control, routing, and call fεaturεs arε supportεd by thε PCSC. Transmission. All PSTN transmission facilities are managed by thε PCSC. Authentication. Authεntication requests and data arε initiatεd by or storεd in thε PCSC. Operations, Ad ministration and Maintenance. All OA&M functions arε initiatεd by the PCSC. 4. 1 .3 Rea l Esta te Depending on the applications, Omnipoint Basε Stations arε designed to be small enough to install with minimal rεal estate requirεmεnts. For εxamplε, Omnipoint's Micro Basε Station at 9"x 4"χ" 12" allows for Base Stations to bε hung from a telεphonε or CATV strand, mounted to a telephone or light pole, or installed in a weather-proof NEMA style enclosure. Omnipoint Base Stations have beεn installed inside of "live" cablε TV amplifier enclosurεs. Indoor modεls may bε mountεd above ceiling tiles in a typical office building with the antennas mounted on either the exterior of the building or inside. Standard Base Station Controllεrs (BSC) handling up to 1600 Voice Ports are likewise comparatively small, and gεnerally require no more rεal εstatε than a phonε closεt where standard 19" equipmεnt may bε placεd. 4.1.4 Opera tions The Omnipoint system provides for comprehensive opεrational support for PCS which will include central monitoring of thε systεm, software upgrades, simple repair procεdurεs, easy installation and test, and the ability to interconnect with a variety of different platforms such as AIN, the Americanized version of GSM, IS-4 1 and ATM based networks. In general, thε following arε provided by Omnipoint: Remote Monitoring. Thε Omnipoint systεm provides for rεmotε monitoring of thε Base Stations and Base Station controllers via a digital facility. Information provided includes loading, diagnostic processes, and other support mechanisms. With this capabil ity, the system can be monitored from a central sitε (pεrhaps by a third party) in conjunction with other network component monitoring (e.g., network control centεr for thε PSTN). Software Upgrades. Omnipoint providεs for rεmotε downloading of software as required for upgrades to Base Stations and Base Station controllers. This approach allows the PCS operator thε ability to upgradε the systεm without hardware changes, maintenance visits to the Basε Station sitεs or Mobilε Station recall. Mobile Station software can be downloaded over-the-air as required for maintenance purposes or for some system upgrades. Repair. Omnipoint Base Stations are extrεmεly small and can bε εasily replaced in the case of a major failure. On spεcific board failures, the system allows for εasy rεmoval and installation of replacement boards in thε field. RF channel cards can bε added or removed independently of one another without disruption of existing service. Base Station controllεrs arε fully redundant and can similarly be rεpairεd with a simplε hot board replacement approach. Field trained technicians that arε either employees of the PCS operator or a third party company wil l service the network components. Omnipoint will arrange for training of thε appropriatε personnel. Network Interconnections. Omnipoint's system will support AIN, American GSM, IS- 4 1 , and ATM-based architecturεs for full feature PCS under sεvεral different deployment scenarios. At thε prεsεnt timε, Omnipoint is working with various equipment manufacturers and potential servicε providers to bring each of thesε systεms to fruition. Network features and services like billing, database (HLR/SCP) access and provisioning, and routing will be provided by Omnipoint's network partners through switching platforms connεctεd to εithεr thε Omnipoint intelligent Base Station or to the Base Station controller, depending on thε architecture chosen by the PCS operator. Since these capabilities will be provided under well documented and understood architectures (i.e , AIN, American GSM, IS-4 1 , and ATM), the detai ls arε not included here. Any modifications to these architectures adopted by the standards bodies will be incorporated into Omnipoint interface or system speci fications. 4.2 Mod u lation a nd Mu l tiple-Access : 4.2.1. Mu ltiplexin g Pla n The Omnipoint system utilizes a unique combination of Frεquεncy, Timε, and Codε Division Multiplexing. Within a cεll, Timε Division Duplεxing (TDD) and Timε Division Multiple Accεss (TD.MA) arε employed, allowing up to 32 simultanεous, 8 Kbps full duplεx usεrs or 64 full duplεx 4 Kbps users, while adjacent cells are set to di fferent frεquεncy channεls (FDMA) undεr a minimal N=3 architεcturε. Cells beyond adjacent cells use a variety of multiplexing tools and capabilities including code (CDMA) and tim slot (TDMA) separation and Timε Slot Interchange (TSI) for further inter-cell multiplexing isolation,. Undεr cεrtain circumstances, Voice Activity Dεtεction (VAD) can be usεd to incrεasε thε numbεr of voice users (theoretically, up to twice the half- duplex number). Going to 4 Kbps also allows up to twice the number of voice users without any changes to thε CAI or thε Basε Station hardwarε. The TDD/TD.VLA structure is based on 2 20 ms polling loop which supports thirty-two, S Kbps full duplεx timε slots of 625 μsεc duration and providεs that εach Mobilε Station be able to aggregate multiple slots to afford a usεr more or lεss data bandwidth as rεquired. Asymmetric data rates can bε supportεd on a frame by frame basis, thus enabling VAD, high spεεd data transport, and data broadcasting. Thus, for broadcast applications, for instancε, all thε data can bε sεt up to emanate from the base to thε Mobilε Station allowing 16 Kbps data transfεr ratε in onε slot, and with slot aggregation up to 5 12 Kbps. All full duplex transmissions from BS to MS, and from MS to BS are synchronous (See Section 4.17), such that from cell to cell, Basε Stations transmit during the allotted portion of the slot, and Mobilε Stations transmit during their allotted time within the slot (See figure A). Within each cell, only the BS or onε of many Mobile Stations transmits at any instant in time. Figure A shows thε timing structurε of thε system. Fi '_εurε A Intra-Cell Multiplexing. Since each Mobilε Station within a cεll is Timε Division Duplεxεd, and Timε Division Multiplexed with all other Mobile Stations in the same cell through a synchronous slot structurε controllεd by thε Base Station, they are not hindered by positional (near/far) restrictions within the cell, providing "perfect" timε isolation between mobiles. Inter-Cell Isolation & Re-Use. On an Inter cell basis, a series of multiplexing tools and capabilities, including TSI, power control, codε orthogonality, antenna diversity and beam directivity, supply significant isolation from cεll to cell. Under most "rεal world" scenarios, propagation charactεristics and significant shadowing (especially at 1 .8 GHz) alone will most often provide sufficient cεll isolation. Additionally, the system takes advantage of mechanisms that provide significantly higher dεgrεεs of isolation between re-used cells, including: Time Slot Interchange (TSI). This function allows a Mobilε or a Base Stations to change thε opεrational time slot i f interference is detected, taking advantage of statistical placεmεnt of Mobilε Stations in both thε original and rε-usεd cells. The system supports very quick TSI, within a single polling loop (i.e., less than 20 msec), as required and available. " Transmitter Power Control. By controlling the Mobile Transmit Power in discrete steps (minimum 3 dB each), the minimal emitted RF power reduces interference into all cells. The Time Slot structure allows for power adjustment in less than 500 μsec, which will mitigate both interference and fading events. Antenna Diversity and Directivity. The system supports both antenna diversity and directional antennas, whether they are steered phased array or sectorized architectures. With the system supporting phased array antennas, highly dirεctional RF beams may bε utilizεd that dramatically dεcrεase interfεrεncε to othεr cells and reduce delay spread. Time Slot Interchange, Power Control, Antenna Divεrsity and Directivity capabilities, couplεd with shadowing, propagation, and statistical location effects, will provide dramatic isolation gains bεtwεεn Base Station and Mobilε Stations sharing thε samε frεquεncy channεl undεr thε reuse plans. Additionally, the Omnipoint system obtains furthεr gains whεn utilized in an επvironmεnt that provides more than three discrete frequency channels. 4.2.2 TDMA Access Stru cture 4.2.2.1 Polling Loop Description Thε Omnipoint polling loop is composεd of 32 full duplεx 8 Kbps timε slots. Each slot is formed of one of three frame types; A) a symmetric base to MS frame and a MS to base frame, B) an asymmetric base to MS frame and the MS to base frame with acknowledgment, or C) a single simplex broadcast frame without acknowledgment. Non-broadcast frames can be in either poll or traffic mode. Addi t ionally, in the Omnipoint system, an ISDN-like "D" channel format is provided in every packet for application-specific information. This information C2n be used for signaling , short message sεrvicε (such as in GSM), voice mail notifications, paging during communications, or other data messaging applications. At the present time, the D channεl is available in its entirεty to thε usεr and is not usεd for any call procεssiπg or Omnipoint system information. LAPD or Q.921 -like error correction algorithms are usεd transmission via thε D channεl to ensure dεlivεry anS " acknowledgment of the information. 4.2.1.3 Packet Contents Thε following is an illustration of an Omnipoint packet wz- cou'd cttner contain eitht normal or control traffic 16 Head Bits 3 Control 3,ts 1 60 Becrer Bits 16 Bit FCW Figurε B Thε nεadεr in thε packet identi fies tne Base Station or MS, packet tyoε, link quality, aπα othεr information rεquirεd by tne systεm for efficient operation Tne packet also contains signaling and/or messaging information in tne D channel ana the bearεr information 4.2.2. En d-to-En d Dela> The routine transfer of voice and data is normally delayed oy tne basic loop duration (20 msεc) dividεd by thε numoεr of slots rεsεrvεd and utilized oy thε particular user 32 Kbps ADPCM voice, for instarce, usεs 4 slots Assuming εqual timε distribution this would havε 20/4=5 msec delay not counting vocoαiπg dεlays V ' ocoding dεlays add linearly 4.2.: Modulation . 4.2.4. Equalization : Channεl equalization is not rεquirεα in Omnipoint's systεm architεcture In fead. σ Rake ' 'e receiver architecture is used to cn !! ect energy over a 2 to 3 usec range ( max. ) of multipath diversit y gains and improve resistance to fading 4.2.5. Chan n el Coding An d Error-Control: The Omnipoint CAI design is set up as a fundamental data transport mechanism, and as such does not inherently presuppose any particular channel coding (othεr than thε spread spectrum coding itself), error handling of channεl data, interleaving, etc. The particular consumer of the data bandwidth can provide for any special handling thε data transfεr rεquirεs at thε application level. For example, thε proprietary S Kbps vocoder provides its own error correction mechanisms within thε bεarεr chaπnεl. Thε only exception to this genεral opεrating assumption is in thε transfer of control information and in thε transfεr of usεr data which is assisted by ARQ error sεnsε and recovery servicεs provided by the CAI control structures. Each frame transmission includεs a 16 bit CRC of thε form: x ' °-χ l 2 ÷x 5÷ [ which is ustc, along with structural charactεristics, to qualify a rεceived frame for further processing. 4.3 Speech Service: 4.3.1. Flexibility: As described in 4.2., the Omnipoint CAI allows thε discrete aggregation of 8 Kbps time slots into larger blocks of voice bandwidth in each basic 20 msec loop. Thus the Omnipoint CAI supports its own proprietary S Kbps CELP algorithms as well as other algorithms of any type and from any source. The aggregation of 2 slots allows the utilization o 16 Kbps algorithms such as 1 6 Kbps ADPCM, 4 slots allows the use of 32 Kbps ADPCM, 5 slots allows the use of 40 Kbps ADPCM (which is particularly useful for in-band transmission of analog modem signals as well as Group II and III fax transmissions.) Although vve have shown thε ability to accommodate a wide variety of voice algorithms it is important to note that data can be transmittεd in incremental bandwidths as well. The current system can also allow thε εntirε basε bandwidth to be utilized by one Mobile Station. In addition to thε aggrεgation of slots to achiεvε highεr data ratεs, Omnipoint's CAI also supports lower rates by allowing thε Mobilε Station to skip a spεcified number of loops. Thus if evεry othεr loop is skippεd thε CAI supports 4 Kbps voice or data; if every fourth loop is utilized, 2 Kbps voice or data is transmitted, and so on. This powerful technique allows future voice and data algorithms to be dεvεloped without changing thε Omnipoint CAI or requiring any hardware changes in the Basε Station. The Omnipoint vocoder is comprised of a high speed digital processor, a 64 Kbps pulsε code modulated μ-iaw companding codec and a methodology for supporting many algorithms which can bε selεcted at call set up time depending on the requested grade of service. Other services are provided by the vocoder, such as echo cancellation, gain control, flow control, data pathiπg, DTMF generation and facilitation of music on hold. The complexity and power requirement of thε vocodεr is dεpεndεπt on the particular algorithm selectεd. The Omnipoint proprietary 8 Kbps algorithm consumes approximately 50 mA of power. The other low rate voice algorithms currently supportεd arε undεr characterization. 4.3.2 Mu ltiple Voice Coder Su ppo rt Selection of the vocoder algorithm is made by the call originating party at call setup timε. This is εither donε by automatically accεssing the user's HLR data basε for thε dεfault sεlection of the vocoders at each end of the link or this can be user selectable. The answering party's vocoders are default selεcted in a similar way. Rate adaptation is accomplished by the normalizing of the data ratε at 64 Kbps PCM in thε Basε Station Controller. Should either of the users require eithεr highεr or lower quality this may bε requestεd after call sεt up by intεraction with thε other party and control interaction with the Mobile Station. 4.3.3 Basic Properties Of Speech Coding: The Omnipoint CAI supports a wide variety of εxisting speech coding algorithms, while at the same time providing architectural mechanisms for supporting the natural evolution in vocoding tεchnology as it advances in the futurε. Currently, thε CCITT G.726 ADPCM standard is supported and available in Omnipoint Mobile Stations as well as a propriεtary 8 Kbps CELP. Virtually any othεr vocodεrs can be supported, like the CCITT IS-54 di '=gi'tal cellular VCELP. The Omnipoint proprietary 8 Kbps CELP combines high voice quality, low complexity, low coding delay, and robustness in high noise conditions. The algorithm has beεn subjected to intensε testing by Omnipoint personnel as well as select industry peers. 68 4.4 Data Service 4.4.1 General Description The Omnipoint system has been designed to serve as an efficient and flexiblε data conduit for a myriad of data, video, multi-media and broadcast applications. Thε dεsign allows ratεs greater than or less than thε basic 8 Kbps rate to be provided to thε end usεr. The ovεr-thε-air protocol providεs 160 bεarεr bits pεr slot pεr 20 millisεconds to an MS. These 160 bearer bits arε protεctεd by a 16 bit FCW. At thε subscribers option ARQ error correction may bε appliεd to thε bεarεr data. A window sizε of two is usεd for the ARQ process. The numbεr of rεtry attempts arε setable by the servicε providεr or subscriber. 4.4.2 Maxim um Probability of Error After ARQ The maximum probability of error after ARQ as seen by thε usεr is: 1 0-2 1 16- 1 ) which is 1.53 X 1 0-7 undetected frame error probabi lity 4.4.3 Mean Delay Caused By ARQ As A Fu nction Of Mean C/I The mean delay per second caused by ARQ at threshold sensitivity / C I is: Delay = 2 * 1 03 * M * BLER milliseconds Wherε: M= next highest integer value of n = the mean number of retry transmissions to achieve the dεsired corrected error rate. ' n=( °_£I_ER J Log(BLER) (- 1 ) Subscriber Bandwidth = The bandwidth of the Subscriber data sεrvicε to thε nearest 8 Kbps BLERD = desirεd block εrror ratε BLER is the block εr or rate of the over-the-air link at desirεd C/I. 4.4.4 Th roughp u t As A Fu n ction O f Mean C I Thε throughput of thε system is defined by: Throughput = Subscri ber Bandwidth bits/sec 1 ÷ 2FER Where: FER = I O "2 4.4.5 Ci rcu i t-Switch ed An d Packet-Switch ed Access To Netwo rk Both circuit-switched and packet switched data access to network facilities can be provided within thε Omnipoint framework. Circuit mode digital data is supportεd across thε air interface. All ISDN data services from S Kbps up to and including 256 Kbps full duplex are supported in increments of 8 Kbps. Sub 8 Kbps rates to 320 Bit s are supported in 160 Bit/s incremεnts. Lowεr ratεs, or ratεs which arε not multiplεs of ihε givεn incremεnts are supported by rate adaptation. All half duplex ISDN data services from 8 Kbps up to and including 5 12 Kbps in S Kbps increments are supportεd. Sub 8 Kbps ratεs to 320 bit/s arε supportεd in 320 Bit/s incrεmεnts. Lowεr ratεs or rates which are not multiplεs of thε givεn incrεmεnts arε supportεd by ratε adaptation. Thε spεcific IWF used is dependent upon the network or circuit switch servicε chosεn in a particular nεtwork. 70 Packet switcnεd cata servicεs may be pro . icεc ZΛΓ ZT o> PAD and IWF access or by contention based packet accεss The system provides full duplex sy nchronous data transfer over-the-air in dynamically variable data rates (see abovε description of ISDN data serv ices) A terminal application may use a data channεl to communicate u uh a P AD and/or IW F using these facilities During times of low data rates the tεrmmal w ill recuce its ovεr-thε-air bandwidth rεquiremεnt accordingly Thε system providεs a fast circuit sεizing protocol Sincε contention for a channεl can occur at this point, it is resolved with an IEEE 802 3-lιkε oackoff procedure Becausε thε overhead for cnannel sεizing ana rεlεasε is vεry low (sub 50 ms and typically, sub 10 ms), a transaction basεd application will acquire a cnannel, build a circuit to the appropriate IWF modulε, sεnd its αata, and rεleasε the channεl εxtrεmεly fast Vεry low packet ratε applications will hav e a very low cnannel access duty cycle and hence a very low overall overhead Hign packet -ate systεms may sεnα multiple packets before channεl rεlεasε 4.4.6 Syn ch ronous Da ta Clocking Synchronous clocking is handlεd on thε network by the IWF Normal blocking techniques arε usεα to buffer data on appropriate er or rεcov ery and clocking boundaries At thε terminal end an additional IWF function is rεquirεd to buffer, clock and recover data bεtwεεn ihε tεrminal and thε SNA devicε 4.5 Reuse Planning: 4.5.1 . Frequency Reuse Omnipoint uses a nominal frequεncy rεusε pattεrn of 3 to mεεt C/I requirements. Omnipoint's use of TDMA to separatε usεrs within a cell makes C/I highly variablε from timε slot to time slot, particularly on thε reverse link Omnipoint's dynamic Time Slot Interchange (TSI) algorithms combined with rapid rεvεrsε link power control significantly improve coveragε probability in a mannεr homologous with thε Dynamic Channεl Allocation (DCA) stratεgy proposεd by othεr systεms Couplεd with directional antennas thesε tεchniquεs providε significant isolation bεtwεεn individual users. 4.5.2 Dyna m ic Cha n nel Allocatio n And/O r Anten n a S ccto riza tion Handsets in the Omnipoint system are frequency agile for operating with any of 2S RF channεl cεntεr frεquεnciεs between 1850- 1990 MHz a: anv Basε Station (thou gh onlv a maximum of 6 RF channεls are probable under thε maximum FCC allocation of 30 MHz pεr operator). The handset can scan to any cεntεr frequency within thε 1.S50- I 990 MHz band in under 1 ms. Basε Stations for use in public networks arε fixed in frεquεncy during operation, but can be changed to any channεl in thε 1850- 1990 MHz band. Rεmote selection of Base Station frequεnciεs can be performed at the PCSC. In unlicensεd bands, thε Base Station will scan for unused frequεnciεs at thε time of initiation, and will dynamically changε frequencies to avoid interference. Both Base Stations and Handsets can also operate in the 2.4GHz unlicensεd band across more than 80 MHz in 5MHz incremεnts. Omnipoint protocols are designed to exploit high-gain steerablε array antεnna designs to increasε rangε, promotε sharing with OFS, improve C/I, and lower delay spread while enhancing system capacity. Unlike most other air interfaces, Omnipoint's TDD/TDMA approach can bε used with a single manifold array antenna; thus only one bεam is nεεded at a given timε. With phased array antenna types, the antenna beam can bε dynamically optimized for each individual usεr in tεrms of pointing dirεction, null dirεction(s), and C/I. By way of contrast, FDD/CDMA or FDD/FDMA air interfaces need two simultanεous beams for each user, onε for thε uplink and one for the downl ink. I f for examplε, thirty two usεrs arε to bε supportεd at a sitε using high gain antennas, FDD/CDMA or FDD FDMA approaches requirε as many as 64 manifolds while Omnipoint's air interfacε needs only one. Since array manifolding is the most costly elemεnt in a phased array antεnna systεm, Omnipoint's air interface provides for much more economical use of high gain stεεrablε antεnnas. 4.5.3 Base Station Pairing With Carrier Frequencies. Frεquεncy/codεsεt planning is currεπtly usεd to set Base Station parameters. MS paramεtεrs arε εstablishεd by those of thε Basε Station(s) with which it is communicating. Although nor rεquirεd, in futurε rεlεasεs, a simulatεd annεaling approach is plannεd to adaptivεly sεlεct Basε Station paramεtεrs; particularly in small cεl l and unlicensed configurations. 72 4.6 Coverage: 4.6.1. Average RF power level (ERP) Maximum EIRP rules recently established by the FCC limiting peak base power to 100 W EIRP will affect forward link design by favoring a morε balancεd link design when using high gain antennas. Any asymmetries in MS recεiver sεnsitivity arε normally compεπsated for by higher transmit powεr at thε BS. Consεquently, we are not willing to speci fy MS sensitivity until such time as FCC rules are finalized after reconsideration. Nominal Basε Station sensitivity is - 100 dBm to produce a Frame Error Rate (FER) of I O" 2 given a C/I of 6 dB, and L=4 diversity. Fig. 3-ι describes expected cell radius based on the COST 23 1 model of median propagation path loss assuming a Base Station antenna height of 10 mεtεrs. Largε scale shadowing effects are assumed log normal with a standard deviation of S dB. Hata- Okumura models are, strictly speaking, not as accuratε at thε prescribed Base Station height of 10 meters since thesε models werε developed for Base Station antenna heights in the 30-200 meter range. Comparing COST 23 1 predictions with Hata, COST 23 1 range predictions fall somewhere between Hata large city urban and Hata large city suburban cases. Omnipoint's air interface architecture provides for extremely rapid handoff bεrwεεn Base Stations allowing for less overlap between cells. This is reflected in Fig - 3- whεrε 75% contours lead to 90% ovεrall covεragε and 90% contours lεad to 99% ovεrall coverage. Thεrε is significant evidence that at lower Basε Station antεnna hεights, neither higher recεivεr sensitivity nor high gain antennas play as critical a role for increasing cell size bεcause of physical obstructions and associated rapid signal strength roll-off. At shorter ranges, signals tend to fall of with a \IR- characteristic while at longer ranges, signals fall off morε rapidly, as high as R7 or R^ at low Base Station antεnna heights. This has been confirmed by a number of researchers^ 9 10 1 1 _ τ n 2 se nse, there is a breakpoint in ^Tclesis Technologies Laboratory, "Experimental License Progress Report", August, 1 991 ^Hcnrik Borjeson, "Outdoor Microcell Measurements at 1700 MHz", IEEE VT-92 Proceedings pp. 927- 93 1 1 0 BelI Atlantic Mobile Systems, "Experimental Report", ! Feb. 1993 propagation coefficient. Depending on the magnitude of the higher coefficient, improving link margin may do little to increase range. Thε numbεr of radiating centers becomes the important parametεr. (Note: This does not mean that directional antennas have no benefit in smaller cells; their directivity can bε used for purposes other than increasing cell radii.) In Fig. 3-2 t we plot expected performance, again using the COST 23 1 propagation model but with 50 meter Base Station antεnna height. Clearly, once the base antenna is elevatεd above the RF clutter range increases significantly. 4.6.2 Maxim u m Outdoor Base Station Spacing Bεcause Omnipoint uses a numbεr of diffεrεnt Base Station antennas, maximum path loss will vary depending on sitε configuration. Figurε E shows maximum path loss for configurations using 300 mW MS peak power and - 100 dBm Base Station sensitivity with the previous noted assumptions. Cell Radii prεdictions are based on a COST 23 1 propagation model with 8 dB log normal standard deviation. Cell Radii for 90/99% Urban Covεragε Probability (log normal std of 8 dB, 300 mW MS) Figure E Figurε F shows thε maximum path loss for configurations using thε same assumptions εxcεpt that thε MS peak powεr is I Watt. ' ' Vinko Erceg et al. "Urban/Suburban Out-of-Sight Propagation Model ing", IEEE Communications Maqazine, June 1 992 Cεll Radii for 90/99% Uroan Coverage Probability (log normal std of S c3, 1 W MS) Base Maximum Cεll Raαius w ith 1 0 Cεll Radius with 50 Station Path Loss (dB) metεr Basε Station mεter Base Station Antenna Antεnna Height Antenna Height Gain (dBd) (miles) (miles) 137 3 0 418/0 3 12 76S/1 3 18 9 143 3 0 602/0 44S 2 545/ 1 896 13 147 3 0 767/0 571 3 243/2 4 16 53 3 103/0 822 664/3 475 26 , 60 3 6S5/1 256 7 129/5 3 12 4.6.3 Adaptive Power Control The Power Con'rpl Pulse is transmitted bv t^e MS j-tst before the time that the BS is expected to transmit to the MS. The PCP thus provid a power measurement of the obde channel to the BS and is the basis for the p w r control command to oe sent to the M A multi-receiver BS can also make en grtenra selection for transmit based on the quality of the PCP signal arriving at the BS In som TDMA systems the latency of the sι?na ground the pollin loop inhibit the use of po^er control. That is. the length of time around the polling loop is too long to qlipw the ! ast transm'ssion to be very useful to es'imnte the chqnre ! losses and impairments. In most fixed station applications, the antenna locations patterns, and power transmitted bv the fixed station mav he adjusted for minimal interference to other fixed stations However, the nature of cellular-like mobile stations is such that they can conflict with other mobile stations at intersecting cel boundaries. This creates (he need for some power control m the mobile stations. For example, a handset operating at the boundary of its BS coverage needs to transmit its full power to stqv in contact. However, a handset operating in the same time slot, relatively close to its own BS. does not need to transmit full po r to have good contact. The BS can measure the channel with the PCP and tell the MS to adjust its power needed. The BS can also use (he PCP to measure the lime delav fro m a MS and estimate its distance from the BS. Further, if the BS knows the power setting of the MS it can also adjust its pwη power as wel Omnipoint's power control algorithm exploits a proprietary Power Control Pulse (PCpTM) technique through which thε MS provides in formation to the Base Station for controlling the transmit power of the MS. The PCP^M ser es several functions including: Provision of both forward and reverse link antenna diversity information. Since the Base Station both receives and transmits on the antεnna having the best Received Signal Quality Indication (RSQI) from the PCP transmitted by thε MSs, thε MSs benefit from antenna selεction diversity even though thεy do not havε εxplicit antenna diversity capabilities at thε MS. This can bε accomplished because Omnipoint's system uses a high speed TDD technique such that the RF channel charactεristics do not change within the slot timε. Provision of a channεl probing function for MS transmit power setting. Based on PCP™ RSQI, thε Basε Station commands the MS to changε transmit power by some discrεte amount relative to its current sεtting. Bεcausε thε εlapsεd timε encompassing the PCP™, the BS transmission, and the MSs bεarεr transmission burst is lεss than 500 μsεc, Omnipoint's power control algorithm counteracts small scale multipath fading effects as well as shadow effects. Provision of a basis for Base Station Assisted Handoff (BAHO) information in control traffic. At this time, forward link power control algorithms are undεr examination. 4.6.4 An ten n a Diversity. As noted, on the rεvεrsε link, thε Basε Station usεs antεnna diversity to combat the effects of fading while receiving and also establishes which antεnna should bε usεd for forward link transmission. Bεcausε of Omnipoint's TDD channεl symmεtry, this has thε effect of providing antenna selection diversity gain with rεspεct to multipath effects in both directions. 4.7 Privacy and Authentication Issues: The Omnipoint system will support authentication (the process of verifying the identity of a usεr, tεrminal and sεrvicε providεr) and validation (the procεss of veri fying that a user and/or tεrminal is authorizεd to access sεrvicεs). Thε authentication and validation procεss should pεrmit thε systεm operator to dεtεct fraudulent wirεlεss devices and/or unauthorized usεrs and/or users before service is granted. This prevention can extend to both spεεch as well as data. " The Omnipoint system will support privacy of signaling and user information (e.g., speech and data) and will maintain the privacy of the user identity and location. The Omnipoint system can allow unauthorized use protection by requiring the user to enter a PIN. The portable will default to requesting thε usεr for the PIN upon powering up thε devicε. This default can be disabled through an appropriate control function. Thε final mεthodology for supporting privacy and authεntication in thε Omnipoint systεm wi ll be dεtεrminεd by industry efforts, speci fically from thε Joint Experts Meeting on Privacy and Authentication unless otherwise determinεd by thε PCS opεrators. 4.7.2 Loss Of En cryption Fra m e Syn c Thε Omnipoint systεm will employ self-synchronizing modε encryption so that calls will not bε lost. 4.8 Handover 4.S.1 Gen eral Descriptio n Thε Omnipoint handover is MS controllεd and divided into 1 6 steps. Step 1 . While the MS is in bεarεr traffic with its Originating Basε Station it mεasurεs thε received signal quality indication (RSQI) of thε link. This valuε togεthεr with thε current frame error rate detεrminεs thε link quality. I f thε link quality drops below threshold 1 , thε mεasurεmεnt thrεshold, thε MS procεeds to step 2. Step 2. When the link drops below the measurement threshold the MS searches during the time slots not requirεd to pass bεarεr traffic to sεarch for other frequency/codes set altεrnativεs. This sεarch is performed on a list of frεquεncy/codεset channεls of both thε Originating Basε Station as wel l as adjacent Base Stations. (This information is downloaded from thε Originating BS.) As thε MS finds εach frεquεncy/codeset it measures the frequency/code sεt's RSQI. In addition thε MS reads a field carried in all BS frames which describεs thε currεnt timε slot utilization of the BS. The MS uses thesε two pieces of information to form a figure of merit for thε various BS including thε Originating BS. The MS sorts thε 3Ss dεtεctεd by figurε of mεrit. Notε that this allows thε MS to measure the quality of other timε slots in thε Originating BS. If these slots are bεttεr than those of surrounding BSs a i imε Slot Interchange handover may be considered which maintains the link to the Ori ginating 3asε Station. 4.S.1.1 Make Befo re B rea k Han dover Step 3. When the link quality drops below threshold 2, the handover threshold, the MS (during a non bearεr slot) will request a handover from the Base Station with thε highεst figurε of mεrit (which may bε a TSI on thε Originating BS). Thε handovεr is rεquεsted from the Base Station by sεizing a slot, sεnding a handover rεquεst signaling mεssage and waiting for an acknowledge from thε 3asε Station. The handover signaling messagε contains a description of the circuit connecting the Originating BS to thε PSTN'. This information was passεd to thε MS at call establishment time. I f thε Basε Station accεpts thε handovεr (by acknowledging) then thε new Base Station becomes thε Tεrminal BS. Notε that the MS maintains the bεarεr channεl with thε Originating BS durin _g> this timε. Stεp 4. Thε Tεrminal BS sεnds thε Basε Station Controller a Note rεquεsting that thε original circuit bε switched from the Originating BS to thε Tεrminal BS. Stεp 5. If thε BSC is common to both Basε Stations, thε normal event called an intra-cluster handover occurs, if the BSC is not common to both Base Stations, then thε procεss continuεs with an Intεr Clustεr Handovεr. Intra Cluster Handover: Stεp 6. Thε BSC bridges and switches thε circuit from thε Originating BS to the Terminal BS. Step 7. Thε BSC sεnds a circuit switch complεte Note to the Originating BS. Stεp 8. Thε BSC sεnds a circuit switch complεte Note to the Terminal BS. Go to "Continue" (Step 13). Inter Cluster Handover: Step 9. If the BSC is not common to both Basε Stations thεn ihε BSC translatεs thε handovεr Notε into thε signaling languagε of the PCSC host and requεsts an intεr clustεr handovεr at thε PCSC lεvεl. In somε nεrwork architεcturεs thε host PCSC cannot accεpt a handovεr rεαuεst from a tεrminating BSC. In this casε an intεrmεdiatε stεp can occur in which thε request is sent to the PCSC via an X.25 link to thε BSC connected to the Originating BS. Thε Originating BSC then translates and relays ihε rεquεst to ihε PCSC. Step 10. The switch is acknowledged by the PCSC. If the PCSC does not directly acknowledge the switch to the Terminating BSC then that message is relayed to the Terminating BSC via X.25 from thε Originating BSC. Stεp 1 1. Thε Originating BSC sends a circuit switch complete Note to the Originating BS. Step 12. Thε Tεrminal BSC sεnds a circuit switch complete Note to thε Tεrminal BS. ' Continuε: Stεp 13. Whεn thε Tεrminal BS receives thε circuit switch complεtε Notε it bεgins paging the MS with a spεcific poll. Stεp 14. Whεn thε Originating BS receives thε circuit switch complεtε Note it si gnals the MS to transfer to the Tεrminal BS. Stεp 1 5. Whεn thε MS rεcεivεs thε signal to transfεr to thε Tεrminal BS or if thε link is lost to thε Originating BS thε MS switches frequency to the Tεrminal BS and searches for a page. Stεp 16. Whεn thε pagε appεars, thε MS completes connection to thε Terminal BS, bearεr channεl connεction is rεsumεd and the handovεr is complεtεd. 4.S.1.2 Brea k Before Ma ke Han dover Should thε link betweεn thε MS and Originating or Tεrminating BS bε completely broken at any time, the MS will search for the highεst quality BS and attεmpt a handovεr without communication with its prεvious BS. This allows thε MS to rεcovεr from situations in which the original link has dεgεnεratεd. 4.8.2 Initiation Delay For an intra-cluster handover thε total delay between the time that a handover is rεcuirεd and thε completion of thε handover, including the re-εstabiishmeπt of thε bεarεr channel , is typically lεss than 10 ms. The maximum intra-cluster handover timε, assuming that communications with thε tεrminal is εrror free, is approximately 40 ms. Inter-clustεr handovεr dεlay is partially dεpεndent upon the dεlays inherent in thε host PCSC and are bεyond thε scopε of this discussion. Dεlays induced by the ovεr-thε-air portion of thε system remain minimal, i.e., in the 10 io 40 ms range. Intra-BS handovεr, or Time Slot Interchange handovεr, has an ovεr-thε-air total delay which is the same as for an intra-cluster handover. Undεr normal circumstancεs the delay is less than one polling loop, 20 ms, and typically lεss than 10ms. Since there is no switching delay, bearεr packets will continue to thε MS with no interruption. Break beforε make handovers will typically take lεss than 250 msεc. assuming adεqu≥tε RF coverage from at least one basε, rεgardlεss of whether intra or intεr clustεr. 4.S.3 Switch Execution Tim e Much of thε iimε rεlaiεd to switch εxεcution is actually duε to transporting Notes between the BS and ihε BSC. For purposεs of handover approximately 200 bits of signaling arε rεquirεd. Over a 64 Kbps bearεr channεl lεss than 4 ms is required for transport. Thus on thε ordεr of 4 ms of open intεrvε! will occur. Thε intra-clustεr BSC switch timε is a few tεn's-of-microsεconds in thε BSC switch matrix. Couplεd with any additional transport timε to and from the BSC's application processor, the entire BSC switch execution time including transport is typically less than 20 msεc. Sincε thε systεm is dεsignεd to usε make bεforε break handover, this should be the maximum loss. Thε intεr-clustεr switching timε is partially dependent upon delays inherent in thε host PCSC and variεs from network architecturε to network architεcturε and arε bεyond thε scopε of this discussion. 4.9 La nd tra nsm ission : Thε Omnipoint backhaul plan has bεεn devised to take advantagε of multiple transport infrastructures. A number of options exist today for thε final switching function. Bellcore is defining what it calls the "generic C" interface. Omnipoint has also demonstrated the capability to provide handoff directly from the CO utilizing ISDN provisioning. A modification to the GSM European standard called the "A" interface (or sometimes the "A-") is likely to be proposed for thε US market. Omnipoint has participated with major switch manufacturers and major local exchange companies in ihε planning and experimentation of backhaul into the PSTN'. Thε dεsign of thε fixed portion of the Omnipoint wireless link places the PSTN-side vocoder, which contains thε εlεctric basεd εcho cancellation logic, at thε Basε Station controllεr. This allows mitigation of all timing at a uniform place in thε systεm rεndering the system, impervious to variation in backhaul stratεgy, such as Cablε TV, ISDN, HDSL or Tl . It should bε notεd that in thε casε of Cablε TV backhaul, thε Basε Station itself is a concise vεrsion of the normal Base Station and includεs a proprietary modem interfacε to thε cablε. Backhaul is accomplished in thε digital data domain. RF and timing concεms arε mitigatεd by thε dεsign of the Basε Station to Basε Station controllεr interfacε structure. Cable TV compatibility - The system supports many existing CATV infrastructures, as well as those most commonly proposεd for futurε installation, including εxtεnsivε usε of fiber. With BSC's placed at thε hεad-εnd and Basε Stations mounted at the CATV nodes, the sysie can support thε types of coax/fiber installations that will likely bε installed to support PCS, as well as the wide variety of other sεrvicεs ε pεctεd to bε offered by the CATV industry. Remote Antenna Drivers (RADs) and Cablε Antεnna Transceivers (CATs) have beεn extensively testεd by Omnipoint as a mεans of coaxial CATV cable transport to extend coveragε from individual Base Stations. Omnipoint (in conjunction with Cox Entεrprisεs) has dεmons:ratεd that vεhicular spεεd handoff can bε achiεvεd across CATs and Basε Stations. Furthεr, onε BS couplεd with four CATs has bεεn shown to providε coverage to 153 homes in a typical hilly, residential neighborhood. 4.10 Base Station Powering: The power transmission method Omnipoint has chosεn is of the low voltage DC typε which includεs a battεry backup and a primary power supply remotε from the Base Station itself. Thε Omnipoint systεm has bεεn designεd with special concern for maintenancε, dεploymεnt convεnience, robustnεss in εxtrεmε εnvironmεntal conditions, εtc. and is rεdundant in all critical areas. Remotε sεnsing by thε OA&M layεr can ascεrtain thε condition of an individual resource in the system and dispatch a servicε unit while thε ailing rεscurcε opεratεs on backup capability. 4.1 1 Ca ll Ha ndling Thε Air Interface Signaling method usεd by thε systεm for network layer signaling is - based upon ISDN Q.93 1/ANSI T1 .607. In order to reduce the bandwidth requirεd for this signaling and to allow compatibility with the properties of an RF link an abbreviated format is usεd in thε ovεr-thε-air messaging. These messages are converted to thε appropriate ISDN or othεr messages at thε BSC. Additional signaling has bεεn' addεd to dεscribε thε rich variations in bandwidth supportεd, to support handover, to support radio resourcε allocation and to support authεntication. 4.1 1.1. Te rm i nal Initialization At power-up the MS sεarchεs for a Basε Station. The MS then sεizes any available slot and rεgistεrs with thε BS. If thε BS already has the MS rεgisterεd it simply acknowledges thε rεgistration rεquest. If not, thε 3S rεgisters thε MS in its stub VLR and sεnds a rεgistration rεquεst Note to the BSC. Oncε thε MS receives an acknowledgment to its registration rεquεst it rεleases the slot and waits for eithεr an alert mεssagε from thε BS or for an outgoing call request from thε subscribεr. Thus, thεrε is no spεcific setup channel. All of the important sub≤cribεr paramεtεrs arε containεd in thε MS or SIM modulε attachεd to the MS. Thε MS usεs anv available slot for rεgistration purposεs. Whilε broadcast channεls εxist for othεr purposes thεrε is no πεεd for a systεm broadcast channel bεcause available and unused time slots can bε usεd to sεnd thε common signaling channεl a general poll mεssagε. Gεnεra! poll mεssagεs contain systεm information and arε an invitation for an MS to sεizε a slot. A BSC receiving a registration rεquεst Note updates its stub VLR and if thε MS is new to the BSC will sεnd a rεgistration rεquεst to thε PCSC. All VLR entries in thε BS arε associatεd with a timer. If no rεgistration has been heard from a MS within the timer pεriod thε VLR εntry for thε associatεd MS will be delεted and notice will be sεnt to ihε BSC. MSs arε rεsponsiblε for rεquεsting rεgistration on a regular basis. Since the registration operation requires few resources this does not posε a grεat systεm load, εvεn whεn a vεry large numbεr of MSs wish to register at the same timε. 4.1 1.2 Call Setup Delay No inband signaling is used for CAI control purposεs. Framεs between thε BS and MS units can bε usεd for εithεr of two purposεs, usεr bεarεr traffic or signaling information, on a framε by framε basis. Oncε a channεl is seizεd an originatε-signaling mεssagε is sεnt to thε BS. Thε BS assigns rεsourcεs to thε call and translatεs thε originate message into a sεtup Notε. This procεss, including sεizurε and thε appropriate acknowledgment, takes a total of three transactions between the BS and MS, each of which takes a slot. Sincε the system will make use of any available slots for these transactions thε operation can take ■ as little as 2 ms and as long as όO ms. The typical sequence will take less than 10 ms Compared to the network call setup timε this delay is insigni ficant. 4. 1 1.3 Ca ll Term ination Alertin g Pla n Alerting starts with thε host PCSC. Thε spεcific opεration of thε host is bεyond thε scope of this discussion, but all PCSCs keεp track of which BSC a givεn MS is currently registεrεd. I f an MS is not in this rεgistration l ist, it is not available to thε systεm. Host VLR's arε kεpt updatεd by rεgistration mεssagεs passed up thε hierarchy by thε BSC's. Whεn a BSC receives a setup mεssage from thε host PCSC it looks up the location of thε addrεssεd MS in its stub VLR. I f thε MS is not found then thε BSC rεturns an εrror to thε PCSC and aborts thε call. Otherwise thε BSC sεnds a sεtup Notε to the BS to which thε MS last reported. If a new registration rεquεst is rεcεived by the BSC whi le the setup is in progress thε BSC rεsεnds the sεtup Note to thε new BS. When the BS receives the setup Notε from thε BSC it sεnds an alεrting mεssagε ovεr onε of thε available slots. Whεn thε MS is not part of a call connection, it duty cycles on a predetermined basis. Each duty cycle it wakes up and checks thε polling loop of its BS for alεrting mεssagεs dεsiinεd for it. It sεes no alεrting traffic or if a timer εxpirεs it rεεntεrs thε dormant modε. I f there is an alerting messagε present for the MS, thε MS responds with an alert rεsponsε. Thε MS thεn audibly alerts thε subscriber. Sincε thε MS is activε for only a small portion of ihε timε the alεrting mechanism is power economical. 4.12 Terminal Mobility Managem ent 4. 12.1 Mobility Management Pla n Most of the mobility management plan has been previously described in the sections on handover (4.8) and call handling (4. 1 1 ). The basic location mεchanism relies on MS registration. Essentially every timε a MS movεs its allεgiancε to a new BS, whether during a connectεd call (handovεr) or whilε thε MS is waiting for an εvεnt (registration), thε MS registers with the new BS. Thε BS updates its VLR and if thε MS was no: prεviously rεgistεrεd with thε BS then thε 3S sεnds notification of rεgistration to thε BSC. Thε BSC updatεs its VLR to reflect thε new location of the MS and sεnds notification to the host PCSC. Incoming calls arε routed to the appropriate BS by using the BSC stub VLR. A handover automatically invokes thε samε sequence as registration. The action of the PCSC and its relationship to othεr systεms is bεyond thε scope of this discussion. 4.12.2 System In terworking. The system is designed to bε couplεd to a number of diffεrεnt host PCSC's. In this capacity thε systεm relies upon the intεrworking functionality of thε host systεm. Thε primε exception is the casε of host systems which do not provide the capability of terminal BSC initiated handovers. In this case a link must bε built from thε tεrminal BS to the originating BS in order to effect handovεr. An X.25 link or Q.93 1 usεr in formation mεssagεs are εxamplεs of how this might be done. Any further discussion of interworking must fall on thε host systεm and is bεyond thε scopε of this documεnt. 4.13 Spectru m Sha ring 4.13.1 PCS-to-OFS Omnipoint's air intεrfacε is dεsignεd to promotε spεctrum sharing with OFS usεrs; particularly in thε early stages of PCS dεploymεnt where capacity is less of a concern. Although many OFS links will still havε to be moved for most of the PCS allocations, with Omnipoint's systεm far fewer OFS links will rεquirε rεlocation. Kεy sharing features include: Direct Sequence Spread Spectrum to lower spεctral density and avoid concεntrating εnεrgy in relatively few OFS narrowband voice channels. 83% of all OFS usεrs employ multiple very narrowband analog SSB-SC-FM signaling formats that arε interferεncε spεctrum presεrving. Consequently, narrowband interferεncε sourcεs can couple into a relatively fe voice channels and violate thε TSB 10E or causε major corruption at low power levels. In some cases, thε entire OFS link can collapse due to spεctral concentration from narrowband PCS transmitters hitting particularly sensitivε frεquεnciεs such as thε pilot frεquεnciεs or control channεls. These sensitivε frεquεnciεs vary with εvεry OFS link. TDMA/TDD such that only onε transmitter is active at a given time within a cell's specific RP frεquεncy. Power coεs not aggregate within a cell, thus effective power coupling into potential victim OFS receivers is not a function of thε number of usεrs active. This is completely different from FDMA-oπly and CDMA-only systems. TDD so thε Omnipoint systεm only needs to find onε unusεd frequency at any givεn cεli location. Systεms employing FDD approaches will neεd to find two frequencies in order to operate at a givεn location. In high OFS density regions, only about 50% of the links follow standard 80 MHz spacing. Statistically, thε usε of TDD for PCS can morε than triple the probabi lity of finding a non-interfering RF channεl as compared to FDD. MSs listen bεforε talk. MSs transmit using the samε frεquεncy as thε corresponding Base Station. Given that Basε Stations havε bεεn coordinatεd with OFS usεrs, thεrε is little likelihood of a MS mistakenly turning on at a damaging frequency. Directional Antenna Systεms reduce requirεd EIRP out of MSs and provide spatial avoidance of Basε Station transmissions. In problematic sharing environmεnts, Basε Stations couplεd to highly directional Basε Station antεnnas vvill opεratε at low EIRP and avoid pointing at ihε potential victim OFS rεcεivεr. Omnidirectional MSs will opεratε at very low EIRP sincε thε Basε Station's antεnna gain makes up for excessive path loss. 4.13.2 PCS-to-PCS Interference from one PCS system to a another PCS system is highly dependent on the nature of the systems that arε to bε coordinatεd. Given that thε FCC has vεry rεccntly issued rulεs on out-of-band emissions requirements, Omnipoint declines comment on this subject at this time. 4Λ4 User-Provided Home Base Units : Thε Omnipoint plan providεs for full support of usεr providεd homε basε units, with MSs that arε fully compatiblε in the public, privatε and business (PBX, Cεntrεx, etc.) domains. Omnipoint's unique ability to usε onε handsεt and CAI for either licεnsεd or unlicεnsεd frεquεnciεs fulfills thε rεquirεments of the PCS vision. Omnipoint's handsets and Base Stations operate in either the new unlicensεd PCS band at 1 890- 1 930MHz or at thε 2.4- 2.4835GHz unlicεnsεd band, thus providing ovεr 120MHz for unlicεnsεd applications. PSTN' intεrfacε capabilitiεs arε supplied via a typical RJ- 1 1 interfacε, with ISDN and othεr interfaces to be supported as rεquirεd. 85 4.15 Example Model Area Deploym ent: 4.15.1 System Capacity 4.15.1.1 Traffic Capacity Each RF Channel Unit supports up to 32 full duplex voice channels using an 8 Kbps vocoder and up to 64 full duplεx voicε channels using a 4 Kbps vocoder. Also up to twice as many voice channels per RF channel can bε supportεd using voicε activity dεtεction (VAD) ' 2. After allowing for various overhεads, each 32 usεr RP Channεl Unit can deliver approximately 20.7 Erlangs and each ό~ user RF channel can deliver 45.9 Erlangs. Thus, the maximum delivered Erlangs per cεll in a systεm with thrεε cεll sεctors and only onε RF channεl pεr sector is approximately 137.7 for purposεs of thεsε modεls. Traffic capacity is rεducεd if nεcεssary to support higher cεll radii as indicated in Scenarios IA and IB. 4.15.1.2 Inform ation Capacity Each RF channεl can dεlivεr up to 256 Kbps full duplex or 5 12 Kbps half duplεx. Although using a six sεctor cεll thε maximum data capacity pεr cεll is 1.536 Mbps full duplεx or 3.072 Mbps half duplεx, for all attached modeling, we assume a maximum of thrεε sεctors pεr cεll and thus a maximum data capacity of 768 Kbps full duplεx and 1 .536 Mbps half duplεx. 4.15.2 Assu m ptions for Model Area Deployment Without agrεεmεnt on key assumptions, allowing each PCS system vendor to presεnt thεir own Modεl Arεa Dεvelopment Scenarios will not facilitate valid comparisons of different PCS systems. Differεncεs in assumptions rεgarding rεasonablε antennae heights, propagation and attenuation modεls, Erlangs pεr subscribεr, and the population density of the areas to be covered will dramatically affect deployment models. More ' - To be conservative we do not assume VAD is used in the following cεll sits modeling. Further, and also to maintain a conservative view, we assum e a max imum of one RF channel per sector and a maximum of three sectors per cell. importantly, without cost information it is nearly impossible to characterize a PCS systεm. Pεrhaps the most significant assumption contained in the JTC specifications is the requirement to assume that a single operator achieves subscriber oeneiration rates equal to 10% of the population and later 20% of ihε population. Considεring that cellular operators have achieved penetration rates of only 2-3% of thε population after more than 10 yεars and that 6- 10 wirεlεss sεrvicε operators could bε compεting in each market, it is highly optimistic to assumε that any onε PCS operator achiεvεs 20% penetration. Furthεr, by choosing 10% penetration as thε starting point for model comparisons, the JTC has ignored the costs and infrastructure implications of both building out initial coveragε as well as achieving only 2-7% penetrations. Given the extremely compεtitivε εnvironmεnt crεated by so many licenses, the greatεst risk facing a nεw PCS εntrant is thε initial capital costs just to providε basic covεragε bεfore any subscribεrs comε on linε. Howevεr, pεr the JTC's rεquεst, wε prεsεnt several possible scenarios below for thε dεfinεd 10% and 20% penetration cases. For al l cases, vve assume a mεdium sizε city consisting of a corε urban arεa of 22.5 square milεs with a population of 500,000 and a suburban arεa with 1 ,500,000 pεople for a total population of 2,000,000 occupying a total arεa of 1367.5 squarε milεs. Wε havε usεd Hata Large City Urban and Suburban propagation modεls, respectively, since the anteπnaε hεights arε abovε 40 feet in all casεs and thεse Hata modεls arε εasier to implement for this introductory phase of thε JTCs modeling rεquirεment. All scenarios assumε 1 watt peak handset power. Assumptions gεnεric to all models Traffic mix: The systεm configurations in all scεnarios offer full, vεhicular speed mobility to all subscribers. The needs of any stationary or pedestrian subscribers arε a subsεt of thε sεrvicεs offered by this full mobility system. Indoor Coverage Occasional Indoor Usage The system configurations shown in thε following scεnarios providε 99% outdoor covεragε. Assuming a l OdB attεnuation loss from penεtrating buildings, the same system configuration yields indoor covεragε of 85% in thε Downtown and Urban arεas and 70% in thε Suburbs. This level of coverage should suffice for thε situations where the subscribεr occasionally wants to usε thε MS insidε a lobby, a parking garagε, or a friεnd's housε. This typε of usagε is assumed in the fol lowing Model Area Deployment scεnarios. Indoor Office Usage Thε Omnipoint system architecturε allows a singlε MS to opεratε on both a public, licεnsed PCS system as well as a private, unlicεnsεd systεm (such as an adjunct to a wirεlεss PBX, Cεntrex or key systεm). Omnipoint's systεm, as notεd, can accεss ovεr 120MHz of unlicεnsεd frεquεnciεs ( 1 890- 1930MHz, 2.4-2.4835GHz). Omnipoint's market research shows that subscribεrs will want to own and opεratε their own Basε Stations when they are using their MS in their offices. This virtually requires ihε use of unlicensed frequεnciεs. Moreover, businesses do not want to pay additional per minute charges for wireless service inside the office and they require wireline quality services whilε at the office. Businesses vvill therefore require wireless adjuncts that will provide higher quality (e.g. ADPCM) wireless service throughout thε office area for use with the samε handsεts that can bε usεd in thε public licεnsed PCS frequencies. Omnipoint's wirεlεss PBX adjuncts and indoor CAI providεs this dual modε accεss today. Indoor Residential Usage Many PCS sεrvicε opεrators will look to providε sεrvicεs for thε residεntial markεt. Omnipoint will providε FCS sεrvicε opεrators with thrεε ways of dεploying such sεrvicεs. Onε way will bε to providε low cost homε Basε Stations such that thε samε handsεts usεd with thε outdoor public PCS nεrwork can opεrate as a cordless phone within thε residence on unlicensεd frεquencies. A second way is to configure the PCS system to provide in-building penetration and vεry high coverage/capacity targεts. Thε third is to providε normal outdoor coverage and install a "wireless loop accεss box" on thε outside of each residεncε (or clustεr of rεsidεncεs). This box would allow a subscriber to use all the existing phones and wiring insidε thε housε, but still usε thε PCS network. Scenario IA — Cellula r-type Traffic at 10% penetra tion. One possible PCS servicε goal is to rεducε the number of cεll sites for initial deployment and to avoid cεll splitting or othεr cεll site upgrades out to large percentage penεtration ratεs. In Scεnario IA we show one possiblε configuration which would providε primarily voicε traffic for cellular type usagε requirements but with 99% coveragε, yεt would not rεquire cell changes out to 10% penetration. Per the assumptions shown below, this scεnario would rεquire only 9 cells for the Urban traffic and 24 cells for the Suburban traffic. Note that because the Suburban cεll radii arε 4.23 milεs, we reducε thε availablε numbεr of timε slots from 32 at 8 Kbps to 29, and from 64 at 4 Kbps to 58. Thus thε cells are configured to provide a maximum of 123.7 Erlangs per cell each, using threε sεctor cells. 89 Scenario IB — Cellular-type Traffic at 20% penetration. Assuming similar cεllular-likε traffic requirements and a conservative maximum of three RF Channels per cell as in Scenario IA, the traffic at 20% penetration can be providεd by 1 8 cεlls in the Urban arεa and 46 cells in thε Suburban arεa. Notε that bεcausε thε Suburban cεll radii arε 3.07 milεs, e change thε availablε numbεr of timε slots from 32 at S Kbps to 30, and from 64 at 4 Kbps to 60. Thus thε cεlls arε configurεd to providε a maximum of 129.3 Erlangs per cεll εach, using thrεε sεctor cεlls. For both Scenario IA and IB, Omnipoint's system costs can be provided for under S50 per subscriber. This does not include cell site acquisition or preparation costs. Scenario II — Zoning Board Constrained Deployment. The rεlativεly small number of cells shown in the above Scenarios prεsumεs that local zoning boards will pεrmit thε construction of many 100- 130 foot towers. With thε potential for 6- 1 0 wireless operators per city, this could mean up to 650 100- 130 foot towers in Scenario IB abovε. Just thε threat of this proliferation is likely to cause zoning boards to severεly constrain the construction of new towers for any new PCS entrant. In this Scenario II wε assume that the PCS operator is constrained to maximum antεnna heights of 40 feet. Wε furthεr assume that lowεr gain antεnjias arε usεd to rεducε installation "real estate" and facilitate obtaining cεll sites. This results in cεll radii of Only 1 .2 milεs in Suburban arεas and only .36 miles in Urban areas. In this Scenario II the PCS network is purely coveragε limited, not capacity limited, since 57 cells are needed to cover thε Urban arεa and 297 cεlls to covεr thε Suburban arεa. Evεn with only onε R_F channel pεr cεll thεrε is amplε capacity to support 10% penetration of the population at cellular-like usagε levels. At 20% penεtration thε Suburban area traffic can still be supportεd with only onε RF channεl pεr cεll whilε the Urban area would rεquire slightly less than two RF channels pεr cεll. Bεcausε Omnipoint's lowεr capacity/shortεr rangε Class 3 and 4 Basε Stations arε considerably lεss expensive than Class 5 and 6 Base Stations, the costs per subscriber remain vεry similar to thosε in Scεnario I. In fact, thε cost of Omnipoint's systεm pεr subscribεr at 20% pεnεtration is actually lowεr in Scεnario II. Obviously, howεvεr, many morε sitεs must bε obtainεd and intεrconnεctεd for Scenario II. But Omnipoint's micro Basε Stations can bε as small as 4" x 6" x 9", which substantially rεducεs thε problem of obtaining and constructing cell sitεs. Omnipoint's Basε Stations havε bεεn strand mountεd on tεlεphonε and cablε TV linεs and installed insidε standard CATV linε amplifier boxes. Thus, for PCS operators which can obtain low cost backhaul from such networks as cable TV providers, LECs, CAPs, etc. Omnipoint's micro Basε Station approach can bε very cost effεctivε. If thε avεrage cost of obtaining sitεs and building 100- 130 foot towers, etc. is 5100K- S 120K in Scenario I, thεn thε total sitε costs in Scenario II will be less, as long as the cost of obtaining sites on existing 40 foot structures (for a 4"x6"x9" micro Base Station) is less than an averagε per sitε cost of roughly S20,000. Notε that because the Suburban cεll radii arε 1.2 milεs, wε rεsεt the numbεr of time slots to 32 at 8 Kbps, and to 64 at 4 Kbps. Thus thε cells are configured to provide a maximum of 137.7 Erlangs pεr cell each, using threε sεctor cεlls. Scenario III -- The "Fixed" Cost PCS RF Network. If due to εithεr zoning rεquirεmεnts or simply the ability for a PCS opεrator to obtain 40 foot cεll sitεs at low εnough costs (and interconnect large numbers of cεll sitεs inexpensively) results in a network deployment as shown in Scenario II, then this nεrwork can support vεry high pεr subscribεr Erlang rεquirεmεnts. For εxamplε, εvεn at .07 Erlangs pεr subscribεr, no additional cεlls are nεεdεd in either the Urban or Suburban areas out to evεn thε 20% pεnεtration levels. More importantly, the marginal cost of adding additional subscribεrs is εxtrεmεly low. Bεcausε A) thε capacity at thε RF lεvεl of thε initial dεploymεnt is so high and B) thε cost of adding subscribεrs is only a fraction of thε cost of adding vocoder transversion cards and line cards at the Basε Station Controllers, this deployment of Omnipoint's PCS System reprεsεnts a largεly "fixed" cost approach to providing PCS. If used in conjunction with low cost interconnεction facilitiεs, this Scεnario rεprεsεnts thε optimal mεthod of dramatically lowεring thε true per minute costs of providing PCS. Recall that any PCS tεchnology will havε to havε hundreds of cεlls if the zoning boards constrain PCS operators to antenna height limitations of 40 feet. Thus, a unique attribute of Omnipoint's architecture is thε choicε of vεry low cost and small sizε, high capacity, micro Base Stations. Costs per subscriber remain well under S50 per subscriber for Omnipoint's portion of this high capacity network, and the marginal costs per subscriber remain extremely low. 92 In real world deploymεnts, thεrε will almost certainly be a mix of antennaε hεights and typεs. Omnipoint providεs six classεs of Basε Stations for this purpose. The ability to usε sitεs on high buildings as wεll as micro Basε Stations on inconspicuous mountings to fill in covεragε or capacity holεs is key to Omnipoint's approach. 4.15.5 CDMA Capa city Red u ction Fa ctor: Sincε Omnipoint's PCS System does not usε thε codes to multiplex usεrs within a cεll, and doεs not usε N= l , this quεstion is only relevant to the co-channel reuse factor. Further, bεcausε of timε slot interchange, power control, and directional antεnnas, this analysis is vεry diffεrεnt than for othεr CDMA systεms. Thε abovε capacity calculations alrεady factor in a C/I = 6dB at N=3. 4.16 Bandwidth Expansion Method 4.17 Synchronization requirements 4.17.1 System Synch ronization 4.17.1.1 Base Station Controller to PCSC The PCSC is somewhat generic in nature as this function can bε filled by a variety of " offεrings availablε today or soon to bε available. In this document PCSC can bε taken to mean any digital switch based structure which provides thε PCS to PSTN iπtεrfacε sεrvicεs such as backhaul of voice and data, HLR, VLR, OAM&P, etc. Thε Base Station controller can bε connεctεd to thε PCSC by various means including conventional digital intεrfacεs availablε today such as ISDN BRJ or PRJ, Tl , or HDSL. Thε only synchronization rεquirεd at this intεrfacε is thε usual alignmεnt rεquired by thεsε transport systεms. 4.17.1.2 Base Station To Base Station Controller - Data Syn ch ron ization Thε Basε Station to Basε Station controllεr intεrfacε can bε an Omnipoint propriεtary intεrfacε basεd on HDSL transport, or an ISDN BRJ intεrfacε, Tl or other digital mεans. In any casε a digital intεrfacε is involvεd which rεquirεs clock/data alignment inherεnt to thε transport mεthod. Additionally, a GPS rεceiver is usεd to extract accurate Coordinated Universal Timε (UTC) onε sεcond clock ticks and these are sεnt up the line to the Base Stations for framε alignmεnt. 4.17.1.3 Base Station To Base Station - Fra m e Synch ronization In order to minimize the interferεncε potεntial, thε Basε Stations transmissions arε synchronized. The timing fid generated at the Basε Station controller is usεd by thε Basε Station for this purposε. Additionally, sincε thε Omnipoint systεm is a TDMA/TDD system the OA&M infrastructure can gather statistics on the quality of individual time slots within bases and can take thε action of rεtiring slots which have some chronic intεrfεrεnce problem to minimize the inefficiεnciεs associatεd with chronic interference avoidance hand-offs. To enablε this powerful maintenancε capability, absolute frame alignment is required and provided by thε onε sεcond UTC timing fid. 4.17.1.4 Mobile Station To Base Station Thε Basε Station providεs thε basic loop timing by frεquency locking to the Base Station controllεr intεrfacε clocks and combining thε UTC one second fid to uniformly begin each basic loop and each transmit frame within that loop. The Mobilε Station frequency locks to the Basε Station symbol transmissions and framε locks to the 3ase Station framε transmissions. 4.17.1.5 Handover Handovεr is accomplished, by the Mobilε Station, by synchronization with and intεrrogation of adjacεnt basεs in ordεr to ascεrtain suitability of thosε basεs. Paramεtεrs such as signal strength, channel integrity (εrror ratε), basε traffic loading, εtc. arε iπcoφorated, by the Mobile Station, in thε handovεr dεcision. Thε Mobilε Station to Basε Station synchronization mεchanism is discussεd elsewhere in this document. 4.17.2 Re-sync method Items 1 -4 abovε arc data synchronization processes only and are not impactεd by rε- synchronization issuεs. By naturε of it's dεsign, the Omnipoint CAI allows tremεndous flexibility in the Mobile Station to ' affect it's communicating environmεnt. The Mobilε Station synchronizεs with a Basε Station by listening for an invitation to communicate in the form of a genεral poll for rεgistration and call initiation purposεs, and spεcific polls for final synchronization and incoming call receipt purposes. Far more detail on this process is provided else where in this document but suffice it to say that the Mobile Station only drops a call whεn no availablε Basε Station can bε hεard or thε Mobilε Station usεr tεrminatεs the call. 4.17.3 Clock Skew Toleran ce Clock skew is not a problem anywhere in the Omnipoint system as all subsystems are frequεncy locked to all adjacent subsystems. 4.18 Im pact of distributed anten na system Omnipoint has had εxtensive experiencε using Rεmote Antεnna Drivers (RADs), especially for use with thε cable TV network. In addition to the analog RAD approach, Omnipoint has developεd a propriεtary experimental CAT (Coaxial Antenna Transceivεr) tεchnology to allow for thε ε.xtεπsion of covεragε from a Basε Station in cablε TV dεployment scεnarios. This experimental CAT technology has been shown to provide cost effective deployment of PCS to cable subscribers, while providing full functionality including handoff and vehicular mobility. For example, one Omnipoint Base Station and fou r CATs covered 153 homes in an experiement conducted in a typical residential su bu rb. Thε CAT architεcturε can also eliminate the delay limitations otherwise found in TDD systems by decoupling the ovεr-thε-air protocol from thε backhaul protocol. Additionally, Omnipoint's Base Stations and/or BSCs can be mounted at fibεr nodεs. Notε that becausε Omnipoint's Basε Stations can bε so small (4"x6"x9") and low cost, thεy can be used instead of "repeater" tεchnologiεs. Repeater techniquεs do not providε any capacity but arε simply extensions of a Base Station. In contrast, each Omnipoint micro Basε Station can providε up to 64 chaπnεls. Omnipoint's Base Stations arε the onlv PCS Base Stations miniaturized to the point where t'nev can be instal led inside standard cable TV amplifier boxes. 4.19 Other information Becausε Omnipoint's systεm is dεsignεd to takε advantagε of thε propεrties of wider bandwidth signal formats (for εxample, 5 MHz to 10 MHz as discussed here and in Omnipoint's expεrimεntal rεports), Omnipoint's systεm specification for opεration at 1.9 GHz arε vεry dεpεndεπt on thε FCC's final tεchnical spεcifications for PCS. Bεcause the FCC's technical recommεndations for 1.9 GHz PCS wεre not available until five businεss days bεforε this JTC submission was duε, Omnipoint may changε various paramεters dεfinεd in this documεnt. Additionally, bεcausε Omnipoint's approach lεnds itself to such flexibility by thε PCS sεrvicε opεrator, Omnipoint may proposε morε than one alternative implementation of this system. For examplε, some potεntial PCS sεrvice operators have requested that Omnipoint explore variations to the basic architecture including using lower data rates and fewer time slots per RF channel to increasε rangε, εtc. Omnipoint alrεady has two vεrsions of thε systεm undεr dεvelopment which implement tradeoffs in these parameters as well as offering a further significant reduction in costs with some reduction in capacity. As befits any true standards effort that allows participation by the service providers, Omnipoint encourages potεntial PCS licεnsε holdεrs to prεsεnt their priorities with rεspεct to the service trade-offs discussed above. PCS2000 System Design Specification and JTC PCS Standard 1. Introduction 1 . 1 Scope and Purpose Tnis American National Standards institute (.ANSI) Interim Standard (IS) has been produced by the Hybrid CDMA / TDMA Tεchnical Advisory Group (TAG) of the Joint Technical Co nmiπεe (JTC). This ANSI Interim Standard describes the PCS2000 systεm design which was pioneered by the Omnipoint Corporation for usε in the United States Personal Communications Serv ices (PCS) frequency bands. This Interim Standard covers PCS2000 system implementation and opεration in the 1 S50 to 1990 MHz licensed and unlicensed frequency bands, within thε .American National Standard public telecommunications network. Tnis IS document includεs both introductory material suitable for informational purposes and technical specifications which arε suitable for usε as an .ANSI standard. Reference is made in this IS to various other National and International standards as summarized in thε Appendix. 1.2 Key Features of thε PCS2000 Design Approach Omnipoint employs Dirεct Sεquεncε Sprεad Spεctrum (DSSS) with Timε Division Multiple Access (TDMA) for PCS digital communications RF links. PCS2000 provides solutions to thε problεms that confront PCS systεm dεvεlopers. First, it mitigates thε problem of interfεrence with OFS usεrs within or nεar the PCS operating area, allowing rapid, undεlayed PCS system deployment. Second, the use of Omnipoint DSSS helps mitigate the PCS link performance degradation causεd by multipath propagation conditions experiεnced in typical mobile PCS εnvironmεnts. Third, PCS2000 accommodates the full range of mobilε hand-off conditions including thosε at freeway speed. Fourth, it permits usε of a bandwidth efficient frequency rεusε factor of N = 3. Finally, PCS2000 with Time Division Duplex (TDD) provides thε lowest cost, least complex implementation of multi¬ user PCS systems. Up to 32 simultanεous users pεr RF channel are accommodated, and a variable data rate up to 256 kbps (full duplex) is available to any user. 1.3 Overview of PCS Services, Features, and Functions Provided Tnis section provides servicε, feature, and function details for the PCS2000 Systεm(s). However, as notεd previously, Omnipoint cannot yεt release details about switch platfroms that will be provided through Omnipoint's infrastructure partners. As these relationships are finalized, this information will be made availablε. Tne PCS2000 System(s) provides a full array of voice and data sεrvicεs through its radio accεss and transport system. The following provides specific information regarding services supported by the PCS2000 systεm(s). 1.3.1 Voice Services The PCS2000 System(s) can providε landlinε quality voicε sεrvicεs to thε εnd usεr for wireless access to the network. Design objectives for the system(s) rεquirε transparεnt operation for usεr-to-πerwork functionality including DTMF tonεs for interactive servicεs, music on hold, and thε provision of activε call features which remain intact evεn after a hand-off between cell sites. Different levεls of voice quality can be providεd by thε systεm(s) by allowing a user to choose his vocoder rate in incrεments of 8 kbps. In the future, even lower vocoder rates without any change to the Basε Stations or thε CAI. Users of the PCS2000 Systεm(s) in a nεrwork configuration can place calls in thε same way as to the way calls are placed from wireline or cellular telεphonεs. Omnipoint today provides handset interfacεs that allow for either cellular-like calling (entεring thε numbεr thεn pressing a call buπon to commence call set-up) or PSTN-like calling (off-hook dial tone and DTMF tones for each digit). The exact implementation of the user interface is programmable and can be readily customized for the servicε opεrator. 1.3.2 PCS2000 PCS-Supportεd Scenarios PCS to PCS Calls: For PCS calls, the called party number will bε idεntifiεd by the PCS Base Station Controller and PCSC as requiring a tεrmination within the PCS nεrwork, eliminating the need to go through the PSTN. Upon receipt of thε caller ID and the destination address, the PCS network registration database (SCP/HLR) is queried to find the current location of thε desired party. If found, the call is routed to the appropriate PCS Base Station and completed. Optionally, a voice mail can be left or network routing to an alternative termination can be provided. PCS to Local PSTN: If a call is made to a local land line phone number, the PCS Basε Station Controller formats and routes thε voice traffic to the PCSC or directly to the local CO Switch, usually via a Tl trunk. Long Distance Calls: Long distance calls made by PCS subscribers will be routed directly by the PCS Base Station Controller or via the PCSC to the inter-exchange carrier of choice, bypassing the LEC. Service Activation: The PCS2000 System(s) will provide for service activation via a PC interfacε to the appropriate nεrwork or systεm databasε. This interface will be available to sales people for direct activation of new subscribers in real time. Subscriber interfaces to the network for changing servicε status or for initial activation could bε supported by Omnipoint at a future timε. Voicε sεrvicεs providεd by Omnipoint will be available to end usεrs in both mobilε and non-mobilε εnvironmεnts. Thε PCS2000 Systεm(s) is capablε of supporting a mix of Basε Station rypεs that will enable the use of both microcεlls and macrocεlls for contiguous wireless coverage and this is significant since PCS is often mistakenly considered to consist of o_πly non- mobile applications or "islands of coveragε". Omnipoint technology allows highway speed vehicular hand-offs even in cεlls that arε substantially smaller; than traditional cellular cells. System(s) features are inherently flexible . because of Omnipoint's transparency to the network switching platform. In the case of LEC applications, The PCS2000 System(s) allows for most business telephone network featurεs to bε availablε to thε εnd user on a wirεless basis. Thesε include fεaturεs such as Custom Calling, Caller ID and other CLASS/ AIN features, Private Virtual Networks (PVN), confεrence calling, do not disturb, custom billing, and many olhεr currεnt and future AlN-basεd sεrviccs. In addition thε Omnipoint PCS Systεm(s) has bεεπ designεd to support the advanced featurεs proposed by the various industry (PCIA) and standards developmεnt (Joint Technical Committee on Wireless .Accεss (JTC)) organizations. 1.3.3 Data Sεrvices Omnipoint views data sεrvices as a significant differentiating capability of PCS over conventional cellular services. As such, a PCS provider must be ablε to provide a form of "data on demand" service that allows for both variable data rates and higher data rates than those within the capability of cεllular. Cellular systems will be able to deliver a maximum raw rate of 19.2 kbps (using CDPD) which delivers only a 9.6 - 13 kbps maximum bearer rate for an entire cell or cell sector. Such systems also typically use a Collision Sense Multiple Access (CSMA) schεme shared by all users which further reduces the data rate which is actually available per user. CDPD is designed only for bursty, low speed, packet data type applications. Omnipoint, in contrast, provides thε ability for the user to request any bandwidth (up to the maximum of thε RF channεl at the time of call origination) that is consistent with the application being used (and for which a PCS operator can chargε a prεmium). For εxamplε, the mobile voice subscriber might rεquirε only an 8 kbps voicε channεl for a vεhicular tεlεphonε call, whereas an office user might rεquεst 32 kbps voicε for εnhancεd voicε quality or transparent data modem or fax support. ■ Thε PCS2000 Systεm(s) supports multiple vocoder rates including 8 and 32 kbps. In addition, a data usεr would have thε ability to requεst εither a small numbεr of timε slots for bursty packεt data or multiple 8 kbps channεls to provide higher data traffic. Up to 256 kbps full duplex, or 512 kbps simplex ratεs can bε supported. Additionally, a slow speed "D" channel accompaniεs every 8 kbps time slot. The system(s) sεcures the necessary bandwidth on call origination for the application desired. Undεr the currεnt PCS2000 PCS dεsign, Omnipoint can provide data servicεs from continuous short message services at only 500 bps up to 256 kbps full duplεx to hand hεld dεvices. Bulk transport of data is also possible through this capability at up to 512 kbps per RF channεl including data acknovvlεdgrnεnts on every packet. This data ratε far εxcεεds thε currεnt maximum 19.2 kbps (which as notεd is rεally roughly 10 kbps aftεr ovεrhεad) limitations of cεllular applications. Furthεr, cεllular will be limited to these low data ratεs for thε foreseeable future. In addition to the user voice/data channel, the Omnipoint design provides for a D channεl that allows for continuous 500 bits/sec of data traffic to every user. Tnis is separatε from (but simultanεous with) the bearer channel. This information can be used for paging applications, notifications (e.g., voicε mail), Short Mεssagε Service (similar to GSM) or other user applications. The simultaneous nature of the D channel will allow messaging εven when the handset is in use. Omnipoint provides bearer rates to the handset that will allow for full fax support through The PCS2000 System(s). Interconnection to a fax device could be a stand alone module or consist of a data port on the handset. Data ratεs for voice circuit fax service can also bε provided through a 32 or 40 kbps ADPCM algorithm which allows the existing installed basε of faxes and modεms dirεct, transparεnt access to the network. Higher speed fax transmission (such as 56/64 kbps) can be providεd through direct data support of The PCS2000 System(s). Broadcast data services such as software downloads, information database services, and other high speεd applications can also be provided by Thε PCS2000 System(s). For εxamplε, a 3.5 MB "εlεctronic" newspaper such as that demonstrated at the PCS Demonstration at the White House in the summer of 1993 could be down loaded by the PCS2000 PCS system(s) wirεlεssly in 55 sεconds. Omnipoint's capability will providε PCS sεrvicε providers with thε potεntia! to providε many unique broadcast services to differentiate their networks. The PCS2000 Systεm(s) will support full 91 1 εmεrgency services. It is also compatible with such ancillary sεrvices as voice mail and fax store and forward, Thε ability to provide thesε sεrvices is largely a function of the network platform, but mεssaging such as notification of voicε mail mεssagεs or fax waiting can be supportεd undεr Omnipoint's D channεl capability. Othεr dεvicεs that can utilize Omnipoint tεchnology includε laptop computers, personal digital assistant (PDA's) devices, video phonεs, and multimεdia devices. Omnipoint has developed palm-sized wireless modems for use with laptop computers and is also the provider of wireless technology for thε largεst manufacturεr of handhεld computers using RF today. Omnipoint can use transparent error detection/corrεction for cεrtain data through use of a CRC, on both thε control information as well as on thε entire packet. Thε protocol also providεs for ARQ at thε application lεvεl for data, sincε this is vastly morε efficient than FEC within the packet 1.3.4 Network Features Supported Tne PCS2000 System(s) providεs radio accεss and transport facilities for PCS services. When coupled with a full fεaturεd switching platform The PCS2000 System(s) will enable most or all of thε features listed on the following page: • Basic POTS • Residential • Business • CLASS • Data • Emεrgency or safety • Attendant Line restriction Hunting Abbreviated dialing Cail waiting / forward / transfer Conferεncε calling IDDD Cεntrεx VN or Virtual Privatε Network Access Paging Private facility Automatic or flexible routing Authorization or account code Messagε detail recording Traffic data Voice mεssaging Call scrεεning / routing Many of thεse fεaturεs, howεver, requirε support from the nεrwork infrastructure connected to The PCS2000 Systεm(s). In some casεs, ancillary εquipmεnt will bε deployed with Thε PCS2000 System(s) and switching systεms to allow servicεs likε billing, tεleconfereπcing, voicε mεssaging etc. These may be providεd by the PCS operator or a third party. 1.4 PCS2000 System Overview This sεction is an overview description of thε components of a PCS2000 systεm and thεir intεrconnεction to a tεlecommunicatioπs network. The purpose of this section, is to providε a basic description of Omnipoint's PCS2000 technology from thε standpoint of a numbεr of potεntial of nεrwork connεctioπ possibilities. Thesε nεrwork connεctions includε LEC basεd PSTN, AIN, GSM, IS-41 and an intelligent Base Station approach. In addition, a Cable TV distribution network connection is presεnted. System Flexibility The various methods of interconnection dεscribed rεquire a level of flexibility that Omnipoint has εnginεered from the inception of The PCS2000 system. Thε PCS2000 system does not necessarily require the modification of existing PSTN nεrwork εquipmεnt. Omnipoint, however is working with potential PCS providεrs, εquipmεnt suppliers and Bεllcore to furthεr refinε the specifications for thε "C" Gεneric Intεrfacε opεrating in AIN' 0.2 and NISDN3, as well as with those planning to implement a US version of thε GSM "A" interfacε. No changεs per se are rεquirεd to the CATV networks specifically for an Omnipoint system. Obviously, to incorporate any PCS systεm a CATV network opεrator must introduce a switch architecture, two way amplifiers, redundancy, etc. Additionally, some form of a Remote Antεnna subsystεm must be deployed if onε is to use the coax portion of the CATV network to extend coverage from a Base Station. The PCS2000 system is dεsigned around an objεct-basεd software architεcturε which allows for flexibility in interconnection to the PSTN, AIN and GSM network infrastrucrurεs and IS— 41 network interconnection. Tnis approach providεs thε PCS opεr tor with flexibility to dεploy whatever network infrastructurε mεεts the appropriate business goals and service descriptions desired. The system usεs internal communications based on ISDN mεssages, callεd "Notes", for passing necessary information among Omnipoint components within the system. These "Notes" are so named as not to confuse them with the ISDN specific protocol itself. Network messages (e.g., Q.931 or others) are convertεd by the system into Omnipoint "Notes" for efficient operation within the Omnipoint hardware platform. 1.4.1 Network Architecture As shown in thε diagram below, The PCS2000 system can interconnect to a variety of network infrastructures including AIN and GSM-based networks, private networks and provide IS-41 network interconnection. Seε Figurε 1 -1. Thε PCS2000 systεm can support AfN and GSM-basεd architεcrurεs for full featurε PCS undεr sεvεra! diffεrεnt deployment scεπarios. At thε prεsεnt time, Omnipoint is working with Northern Telecom and other switch equipment manufacturers, and potεntial sεrvice providεrs to bring each of thesε systεms to markεt. PCS2000 can support various sεrvicε implεmentations through intεrconnεction with LEC network, CATV network, new build (PCS operator PCSC architecture) or as an extension to a cellular system (different RF access, but some co-located equipment). PCS2000 provides full featured PCS, including high speed data applications and full, high speed mobility. Pedestrian speed or Telepoint-type implεmεntations of PCS that arε envisioned by somε potεntial operators can also bε providεd by limiting thε functionality of thε systεm. 1.4.1.1 PCS2000 Systεm Components The following components are includεd in thε various implementations of Omnipoint's PCS2000 System in PCS networks: Base Station Omnipoint Base Station radio equipment providεs for multiple usεrs in a PCS εnvironmεnt. Up to sixty four 8 Kbps time slots of bearer information per 5 MHz RF channεl is available. Using voice activity detection (VAD), however, a conservative maximum of 32 full duplex voice channels pεr 5 MHz RF channel is assumεd for economic analysis and cell site planning. Using 4 Kbps vocoders, up to 64 non-VAD full duplex voice channεls may also be provided per 5 MHz channel. The Base Station formats and sεnds digital information either to The PCS2000 Systεm Basε Station Controllεr, the PCSC or directly to the PSTN, depending on the PCS operators choice of networks. Base stations arε connεcted to the Base Station Controllεr by a variεty of transport mεans including ISDN, standard linεs, lεasεd Tl and Fractional Tl linεs, cablε TV, microwavε, εtc. Base Station Controller (BSC) Tne Base Station Controller concεntratεs inputs from multiple Base Stations, performs inter-Basε Station hand-offs, convεrts and formats both channel and signaling information for prεsεntation to thε network, manages thε local cachε VLR databasε, providεs multiple network interfaces and supports basic O.A&M functions. The Base Station Controller, under control of the PTSO or PSTN, will manage local rεgistration/vεrification for its associatεd Basε Stations and provide updates to thε PCS network or centralizεd SCP/HLR. CAT Cable Antεnna Transceivεr, dεvεlopεd by Omnipoint to economically extεnd covεragε from a Base Station; can also be used in cable TV infrastructure deployments. CO Switch Central Office Switch, owned by thε local tεlephone company. Wire Center Houses one or morε CO Switchεs and sεrves a geographic arεa, usually with typical maximum covεragε radius of 13,000 to 15,000 fεεt (largεr in suburban and rural arεas). Providεs lines within the CO Wirε Center service area. PCS Cell PCS Network antεnna sitεs supporting onε or more Basε Station RF transceivers depending on coverage and subscriber capacity requirements. PCS Node Collection of Base Stations into onε Base Station Controller in thε PCS Network, where traffic from PCS Systεm Cells arε routed for concentration, processing, hand-off and prεsεntation to or from thε PCSC or PSTN. PCSC PCS Switching System. This is the primary switching and control point used by the PCS Network to perform network control, manage the SCP/HLR data bases and control access to thε PSTN. Thε PCSC functionality could also be provided by thε PSTN in casεs whεre thε LEC providεs direct PCS support. The PCSC providεs co nεction and advancεd switching of traffic to and from PCS Nodes (Basε Station Controllers) and interconnection to the PSTN and inter-change carrier networks. Tl or Fractional Tl Leased Trunks High speεd (up to 1.544 Mbps) digital facilitiεs for hauling intcr-CO traffic. Thεsε arε providεd within thε samε LATA by thε local εxchangε carriεr and by thε intεr εxchangε carrier for intεr-L.ATA connections. Transversioπ Cards Converts the packet stream to and from the Base Stations to vocoded format and convεrts the vocoder rate used in the CAI to thε standard ratε usεd by the PTSO or the CO (e.g., 32 or 64 Kbps). These cards are only needεd at the point whεrε thε call lεavεs thε PCS systεm and interfaces with the PSTN. Thεy arε shown in this model as implεmentεd in the Basε Station Controllεr, although thεy could bε implεmεntεd only at thε PTSO. 1.4. 1.2 Base Station Controller Clustεr Nodεs) Omnipoint has dεvelopεd its Digital Trunk Link Systεm and Base Station Controllεr which will form thε basis for most of Omnipoint's commercial PCS System deployment. As shown in Figure 1 -2, thε Omnipoint PCS Systεm Node will accommodatε a variety of interfaces and network connections for optimal performance at minimal cost. Sεε Figure 1 -2 Interconnections from Basε Stations to switching platforms (BSCs, PCSC, and/or the PSTN) will support direct Tl , FT1 , ISDN, microwave links, fiber, and coax cable. Backhaul from thε BSCs to thε PTSO or PSTN will also bε providεd through a variety of methods, including Tl , ISDN, microwave, etc. 1.4.1.3 Network Architecture (LEC-PSTN) Network Interconnection Figure 1-3 illustrates the basic Omnipoint architεcture for interconnection to the PSTN or another switch platform (Base Station Controller or stand-alone PCS switch). The systεm supports analog lines, as well as digital interfaces (including ISDN). PCS2000 Base Stations connect to either the PSTN directly (for LEC-basεd .AIN intelligent Ba_e Station deployments) or to a Base Station Controller (for othεr network implεmεntations, including AIN', GSM, and IS-41 based networks). Basε Station Controllers (BSCs) provide for local switching and fast handoff. In thε Basε Station Controllεr casε, thε PSTN or a PCS switch connεcts to the BSC for call delivery and outgoing calls. BSC connection to PSTN utilizes the Bellcore "Generic C" interfacε which includεs Q.921 , Q.931 and modifications to Q.93 1. Rεfεrεncε CCITT, Digital Subscribεr Signalling System No. 1 (DSS 1), Data Link Layer. Omnipoint PCS Systεms can bε interconnected to PCSC switches to provide inter- node switching, SCP/HLR database support and centralized network OA&M capabilities. While the PCS Systεm can usε existing switch and network architecturεs, including LEC and CAP networks, Omnipoint is working with Northern Telεcom and other major switching vendors to develop specific PCS solutions for even greater future efficieny and lower network deployment costs. In particular AIN and GSM-based platforms will bε offεrεd, as well as IS-41 intεrconnεctions. Intelligent Base Station Characteristics PCS2000 is unique in that it may bε deployed using either a Base Station Controllεr (BSC) to managε handoffs and local switching or it may employ an Intelligent Base Station (IBS) architecture that utilizes the PSTN for this functionality in AIN type infrastructures. Omnipoint's IBS uses ISDN mεssaging for rεgistration, call delivery and handoff via a dirεct CO connection. Tne hardware platform used for die IBS is a modified Base Station (incorporating a BRJ card, additional intelligence and local vocoding) . IBS Connection to PSTN utilizes the Bellcore "Generic C" interface which includes Q.921, Q.931 and modifications to Q.931 1.4.1.4 Network Architecture (AIN) AIN Networks Omnipoint will support a variety of AIN network infrastructures including AIN 0.0 (initially) through AIN 0.2 (or higher as AIN evolves) for full ISDN interconnεctivity, including network database support and handoffs via LEC or CAP central offices. Signaling between network elemεnts will consist primarily of standard signaling protocols including SS7 and IS-41. PCS2000 is unique in being able to be deployed using either a Base Station Controllεr (BSC) to manage handoffs and local switching or to use an Intelligent Base Station (IBS) architecture that utilizes the PSTN for this functionality for AIN type infrastructures. The Omnipoint IBS uses ' ISDN messaging for registration, call delivεry and handoff via a dirεct CO connεction. Tnε hardware platform usεd for the IBS is a modified Base Station (to incorporate a BRI card, additional intelligεπcε and local vocoding). See Figure 1-4 Omnipoint has tεstεd National ISDN- 1 Base Station intεrfacεs including direct interconnection to an .AIN basεd CO switch. In this configuration the system has demonstratεd handoff, two way calling, and registration. Support for ISDN upgrades will be provided by Omnipoint as supported by NISDN-3 for interconnεction to thε PSTN' (as this bεcomes available from the switch vεndors). Omnipoint is also working with several vendors to provide SS7 interconnεctivity to εnsure SCP involvεmεnt in the network architecture for PCS, while also allowing for εnhanced network services (i.e., CLASS, other AIN features) to be providεd to εnd users. 1.4.1.5 Network Architecture (GSM Networks) GSM Networks A similar architecture is usεd for intεrconnεction to GSM networks via die "A" interfacε, εxcept that thε fεaturεs and functionality arε provided instead by a GSM network infrastructure owned by the PCS operator (as shown below). See Figure 1-5 Note that in this particular implementation of PCS2000, the GSM architecture interconnects through the defined "A" interface. Features and functionality of GSM are passed to and from PCS2000 over this network interface in a manner that is transparent to the end user. 1.4.1.6 Network Architecture (Alternative Networks - Cable) See Figure 1-6 Cable TV Networks Omnipoint's Basε Stations are the only PCS Base Stations miniaturized to the point where they can be installed inside standard cable TV amplifiεr boxεs. Furthεr, wε arε alrεady tεsting sεvεral diffεrεnt approachεs, including interfacing to analog Remotε Antεnna systεms and the use of digital transport mechanisms. One of the tεsts usεs Tl and FT1 digital multiplexer outputs from the CATV network, and basic rate (BRI) ISDN links to transport digital channels as shown below. This ISDN-transport capability is in prototype testing now. In addition to the analog Rεmotε approach notεd above, Omnipoint has dεvelopεd the CAT (Coaxial Antεnna Transceiver) to allow for the extension of coverage from a Base Station in cablε TV dεploymεnt scεnarios. This dεvicε was succεssfully tεsted and shown to provide cost effεctive deployment of PCS to cable subscribers, while providing full functionality including handoff and vehicular mobility. Specifically, onε Omnipoint Basε Station and four CATs covεred 153 homεs in a rεsidεntial suburb of San Diεgo in testing with Cox Enterprises. Additionally, Omnipoint's Base Stations and/or BSCs can be mountεd at fiber nodes. 1.4.1.7 Network Interco nεction (Transport Options) See Figure 1-7 Transport Options As notεd throughout this document, Omnipoint supports a variety of network infrastructures using many different physical interfaces. Fractional Tl , Tl , and^or ISDN BRIs will be used for most PCS deployments. These rates will be earned by either HDSL, dedicatεd digital LEC facilitiεs, or privatε transport (e.g., microwave, CATV, fiber). As noted abovε, εach standard RF channεl can providε a maximum of sixty four 8 Kbps bεarεr channεl links nεt of all ovεrhεads and guard timεs. Thus, thεsε links can be carried by a FT1 link (total bearεr data ratε of 512 Kbps). However, under normal usage a standard thrεε sεctor cεll with thrεε RF cha nεls will rεquirε less than a full rate Tl ( 1.544 Mbps) for the Eriang traffic actually delivεrεd to thε BSC. Microwave links can be usεd with PCS2000, particularly in arεas whεrε long distancε backhaul is rεquirεd and the associated higher costs can be justified. X.25 and SS7 are thε links of choicε for network data base access from PCS switching equipmεnt although virtually any data sεrvice will suffice. In general, Omnipoint supports ISDN and X.25 from the Base Station or BSC to the PSTN or PCSC. SS7 is used from the switching platforms to the network. IS-41 signaling is also supported. Omnipoint will provide database access capabilities that are based on US standards should they differ from these already standard interfaces. NETWORK INTERCONNECTION (SOFTWARE) Software Development PCS2000 is designed around an object-based software architecture which allows for flexibility in interconnεction to a number of network infrastructures and equipment manufacturers' equipment. Tne system uses internal messaging based on ISDN messages called "Notes" (so as not to confuse them with ISDN or other network-specific "messagεs") which arε based on the Q.931 and Q.921 protocols for passing necεssary information among Omnipoint components within the systεm. Messagεs from thε nεtwork (e.g., Q.93 1) are thus converted by the PCS2000 System into Omnipoint "Notes" for efficient operation within thε Omnipoint hardware platform. This approach provides the PCS operator with flexibility to deploy whatever network infrastructure meets the appropriate business goals and servicε descriptions desired. i .4.1.8 Network Interconnεction (Operation Support Systems) Operational Support Systems Cell site diagnostics are performed remotely through either the control channεl on thε digital link rεsidεnt in thε Basε Station or a dial up modεm for some implemεntations. Thεsε diagnostics can bε performed on each component board of the Base Station. In addition, PCS2000 provides for remotε monitoring and downloading of software as required to Basε Stations and Base Station Controllers. Some handset software can also be downloaded over-the-air as requirεd for maintenance purposes or for some system upgrades. For small Base Stations, very little prevεntativε maintenancε is anticipatεd other than monitoring for εnvironmental degradation when mountεd outdoors. In largεr cεll configurations, traditional prεvεntativε maintεnancε on thε Basε Stations and/or antεnna arrays is prεscribed. In general, PCS2000 is very diffεrεnt from εxisting cellular in sizε of the equipment (a standard sized, 32 voice channεl Base Station is only 4"x4"xl 0") and in maintenance requirements for most Base Station locations in urban areas. A.s noted, Omnipoint has the only PCS Base Stations small enough to fit inside many existing enclosures including standard CATV amplifier boxes. Base stations are designεd to allow for εasy circuit board replacement or for very rapid wholesale swap out of thε entirε Ba≤ε Station. This will be very εasy duε to the small size profile of the Omnipoint Base Station. Tne RF equipment consists of the radio board in the Base Station which can be alarmed to a central site via thε internal Base Station modem. Additional alarms for power and other components are also incorporated into the design. Functionality to provide alarm services to other network components (BSC, PCSC, etc.) arε integrated into a total network solution through the switching platform used. Billing will be provided by industry standard network OA&M platforms used in conjunction with Omnipoint networks. The information requirεd for traffic rεporting and dεtailεd billing processes will be made available to the network by the Omnipoint Base Stations and BSC for all calls. A separate adjunct processor for billing is also supported by the system if this is desired for service by a third party provider. Omnipoint Base Stations will provide the necessary information to the network for billing purposes as requirεd by thε switching platforms utilizεd. Functions to be supportεd by thε billing systεm includε information collection (from both IECs and LECs), bill preparation, and report gεneration. Thε PCS opεrator (or a dεsignatεd third party) could also sεt up collεcϊions/ customεr sεrvicεs and funds managεmεnt procεsses. 1.4.1.9 Mobility Managemεnt Overview Mobility Management Omnipoint utilizes a handoff (terminal mobility) schemε that is diffεrεnt from that usεd by any othεr fully mobilε wirεlεss systεm. PCS2000 uses a unique "mobile directεd" and "mobilε centric" handoff tεchniquε. In this approach, the mobilε tεrminal makεs thε dεcision to handoff between cells and directs the Base Station Controller or network to make a line switch once an alternative Base Station is acquired. Tnis approach contrasts with "network directεd" or "network centric" approaches such as AMPS and IS-54 cεllular or GSM. Evεn with "Mobile Assisted Handoff (MAHO) in which the network collεcts information and dirεcts all or most of the handoff functions, thε mobilε is usεd mainly as an additional listening post with the network still directing thε handoff, which thεrεfore rεquirεs significant signaling and mεssaging bεrwεεn base stations, BSCs and switches and handoffs thus will take much longer. Also of note in Lhe Omnipoint handoff procεdurε is thε fact that thε systεm can perform eithεr a "make beforε break" handoff for seamless handoffs or a "break bεforε makε" in εmεrgency situations where all communications with a Base Station are lost prior to a new connection being established. "Make before break" handoffs do provide for seamlεss coverage and undetectable handoffs. In the Omnipoint approach the terminal can listen for other Base Stations during idle time slots and determine which Basε Stations arε within range and are candidates for handoff. The case of "break before make" is typified in the sudden shadowing scenario. This example occurs when a connection with the currεnt base is lost due to a severε signal blockage (e.g. worsε than 40 dB) nεar the limit of the cell range such as can occur when turning a comer quickly in a dense urban high rise area. In this situation, the terminal previously had created a "priority list" of available Base Stations in thε vicinity and will rεεstablish contact with a new Base Station, probably on a new frεquεncy and a nεw time slot. The terminal includes a "persistence" parameter which will preclude call tear down from occurring before a duplex connection is fully reestablished. The true "hard handoff" problem (i.e., a lost air channel) is handled very quickly by PCS2000 through the terminal's ability to re-acquire the normal Base Station or an alternative Base Station in 16-250 ms even when no information is available to the handset when the link was lost. In contrast, complete loss of a link in traditional cellular architectures becomes a "dropped call." When the handset determines that a handoff is appropriate, the terminal acquires an air channel on the new Base Station and notifies the BSC to switch the incoming phone line from the old base to the new base as shown below. See Fig. 1-8. This process takes from 4 ms to 32 ms and can be achieved in most circumstances without missing a single packet given proper RF coverage. Even in the emergency "break before make" handoff, the handoff can be accomplished in 16-250 msec as shown below. See Fig. 1-9. As previously mentioned, one of the major benefits of Omnipoint's approach is that it allows for mobile speed handoffs (65MPH) even in very small cells (as already demonstrated by Omnipoint in cells of less than 1000 feet, as well as in cells of up to 20 miles in diameter) . Hysteresis measurements from multiple bases can be maintained by the handset in PCS2000 to reduce the terminal "thrashing" between Base Stations and thus consuming capacity. This is an important design parameter to minimize air channel resources that must be allocated for handoff by the system. PCS2000 uses both RSSI for channel quality measurements, as well as measurements on both frame errors and the type of errors as an indication of link quality. When the scanning threshold is reached, the handset scans for an alternative time slot in the same RF channel first. This is used for time slot interchange (TSI) which provides a dramatic improvement in the cell's average C/I ratio and the reuse planning. If TSI cannot improve the channel, the handset scans for the frequencies in the adjacent Base Stations during the time slots in which it is not communicating. From the common signaling information being transmitted by the Base Stations, the handset can determine both the link quality, as well as the capacity available on the Base Station. When the handoff threshold is reached, the handset will change frequencies and direct the new Base Station to notify the BSC to bridge the call to the new Base Station channel. When appropriate, the handset further directs the BSC to shut down the bridge which completes the switch of the call. Intercluster handoffs are managed in the PCS2000 System via the network platform chosen by the PCS operator (i.e., the PSTN in the Intelligent Base Station approach) or through the PCS operator's switching infrastructure (PCSC aDDroach) . 2. PCS2000 System Description Protocol Architecture The Omnipoint system provides a unique protocol architecture that is optimized for PCS, utilizing specific benefits of FDMA, TDMA, and CDMA technologies. Care is taken with this approach to provide for features and services well beyond those that are available from other air interfaces, while ensuring that costs remain significantly lower than other approaches. Omnipoint's approach also allows for effective in-building operation in the unlicensed bands as well as in the licensed PCS frequencies. Multiplexing and Cell Separation The Omnipoint system uses a patented combination of CDMA, TDMA, and FDMA for separation of users and cells. Within a cell, a high speed direct sequence spread spectrum TDMA protocol is used for separating users . SEE FIGURE 2-1 As shown in Figure 2-1, adjacent cells are separated by frequency (FDMA) with CDMA being used to improve the re-use pattern to an N=3 in the standard configuration when frequencies are repeated. Additionally, Time Slot Interchange (TSI) and directional antennas are employed to create further isolation of users across cells. Note that each user within a cell can use the same set of direct sequence codesets . This is contrary to CDMA- only systems that use codes for user separation within a cell. Omnipoint's system uses a different codeset each time the same frequency is reused (noted as Cl, C2, and C3 in the preceding picture) . The spreading codes are also used within a cell to achieve significantly higher data rates and thus more TDMA users per RF channel than generally thought possible with traditional TDMA systems for fully mobile applications. This direct sequence spread spectrum approach is not a traditional use of CDMA, but is a unique way of using code technology for a wireless system. In the Omnipoint system, code separation is used in combination with spatial and temporal separation to ensure that users on the same frequency in different cells do not interfere with each other. The most significant benefit of Omnipoint's system architecture is that the cost per user channel declines as the number of users increases per base station, unlike any other system. Generally, in traditional cellular approaches the cost per voice channel remains linear with each additional, simultaneous user. As a consequence, Omnipoint's system offers a five to twenty fold reduction in the cost of providing the voice channels throughout the cell sites. The Omnipoint approach is also very different from CDMA-only systems that rely on precision power control algorithms and require soft hand-off to achieve high capacity claims and to mitigate near/far problems, resulting in the associated cost and complexity in handsets, base stations and base station controllers. Omnipoint's system could use soft hand-off if cost were unimportant, but does not require it to meet PCS performance and capacity demands. Additionally, with the Omnipoint system the interference generated by an entire cell is never more than a single user, since no more than one transmitter in a cell is on at any instant in time. This is particularly important for frequency planning and OFS coordination in early PCS deployments . 2.1 PCS RF Frεquεncy/PN Codε Reuse Plan DSSS carrier modulation permits Omnipoint to usε a vεry εfficiεnt Frεquεncy Rεusε factor of N = 3 allocating diffεrεnt carriεr frεquencies to adjacεnt PCS cεlls. Intεrfεrεncε bεrwεεn adjacεnt cεlls is also mitigatεd by assigning diffεrεnt orthogonal PN codεs to cεlls in adjacεnt clustεrs, as shown in Figurε 2.1. Interferεncε bεtween cells using the same carrier frεquεncy is rεducεd by thε propagation loss due to the distance separating the cells (no two same frequεncy cells are lεss than two cεlls away from one another) and also by the Processing Gain of systems using the same carrier frequencies. 2.2 Frequency Parameters 2.2.1 RF Channel Centεr Frequεncies Bandwidths When operating in thε PCS A, B, or C PCS frεquεncy bands, each of which is 15 MHz wide, PCS2000 RF centεr frεquεnciεs arε placεd at 2.5 MHz, 7.5 MHz, and 12.5 MHz from thε lowεst band εdgε of the thrεe bands. For the D, E, and F bands, which arε εach 5 MHz widε, thε single RF carrier frequεncy is placεd in thε center of thε band, and a frεquεncy rεuse factor of N = 1 must be used bεcausε thε DSSS signal has a 5 MHz bandwidth. Tnerεforε, thε rεquirεd intercell interfεrεncε rεjection must be obtained by PN code orthogonality, and the use of sectorized antenna patterns. Time Slot Interchangε (TSI) may also be employed to mitigate intercεll intεrfεrεnce. 2.2.2.1 Unlicensed RF Center Frequencies/Bandwidths Whεn dεploying of The PCS2000 system in the PCS Unlicensed band, which is allocated 20 MHz of bandwidth, but for which individual channel bandwiddis are only 1.25 MHz wide, DSSS chip rate will be reduced to approximately 1.25 Mcps. TDMA burst rate, or number of TDMA time slots per frame will also be reduced to maintain the required DSSS Processing Gain for intercell interference rejection. A non-spread TDMA/TDD signal modulation format for operation in the unlicensed band may also be provided. 2.3 .Antenna Characteristics 2.3.1 Mobile Station The Mobile Station (MS) handset employs a halfwave dipolε antεnna which is linearly polarized and provides a gain of 2 dB with an omnidirectional pattern perpεndicular to thε antεnna axis.. At a nominal PCS frεquεncy of 1900 MHz, a half wavelength is approximately 3 inches, which fits well within a handset envεlopε. 2.3.2 Base Station 2.3.2.1. Omnidirectional Pattern Differεnt typεs of antεnnas arε availablε for thε Basε Station (BS), dεpending on the PCS application. For low density suburban or rural applications an Omnidirectional antenna is used to provide maximum of coverage with the lowe number of Basε Stations. For this application, an omnidirεctional antena may bε employed for the BS with a vertical gain of approximately 9 dB. Thε 9 dB of gai pεrmits a rεlativεly largε radius cεll εven with an omnidirectional horizontal paπεm. 2.3.2.2 Dirεctional/High Gain Configurations Suburban and low dεnsity urban areas, directional antennas with 120 degreε azimuth bεamwidths and 9 dB vertical gain are used so that a cell can be sεctorizεd into 3 parts, with εach sεctor accommodating 32 full duplex 8 kbps users. To permit a single BS to cover large sparsely populated area, a steered arra antenna with up to 20 dB of horizontal directivity can be used. This antenna is sequεntially steered to each MS within its cεll during that mobile's assignεd TDMA timε slot. Because Omnipoint utilizes Time Division Duplexing (TDD) the same antenna is used for both transmission and reception, providing reciproca forward and reverse link propagation characteristics. This antenna utilizes circula polarization, so that high level delayεd clutter signals reflected from buildings, etc., within the beam, do not interfere with the received signals from the mobile units (reflectεd signals are rεversed in polarization, and are rejected by the BS antenna). Note that high gain, directional antennas also reduce the delay spread i sevεre multipath εnvironmεnts by rejecting multipath components arriving from outside thε main bεam of the antenna. 2.3.2.3 Classes of Base Stations The PCS2000 System cεll uses one of sεvεral antεnna configurations in combination with onε or morε Omnipoint Basε Station(s) to bεst mεεt location covεragε and subscribεr dεnsity rεquirεmεnts. Thεsε configurations arε arranged by capability basεd on rangε and capacity. Tnεrε arε a total of six classεs of Basε Stations within thε PCS systεm offering. Class 1 to 3 Base Stations use 3 dB, 9 dB, or 13 dB gain antennas. Rangε can bε extended with the following configurations: Base Station Type Antennae Characteristics Class 4 Size: 9 inches by 30 inches by 3 inches, Weight: approximately 5.5 lbs. - used to extend coverage and or cell capacity with up to 15d3i gain. Class 5 Size: 1 8 inches by 36 inches by 5 inches, Weight: approximately 20 lbs. - used to extend coverage and/or cell capacity with up to 21 dBi gain. Tightly integratεd with Omnipoint's CAI and configurable with additional Base Stations per cell to further expand cεll capacity. Class 6 Sizε: 3 ft. by 6 ft. by 6 inchεs, Weight: approximately 30 lbs. — used to extend coveragε and or cεll capacity with up to 28dBi gain. Tightly intεgratεd with Omnipoint's CAI and configurable with multiple base stations. Used primarily in urban and suburban areas along with 100 foot or higher antennas to maximize coverage areas. Omnipoint has included several antenna options for deploying small to large cell configurations. In addition, Omnipoint is working with several antenna vendors toward intεgration of "smart" antenna configurations allowing high gain with directional tracking at the cell site. This approach differs from standard sectorizing of cεll sitεs to incrεasε capacity. Antennas with a large number of array elements per high gain antεnna arε under development. In general, these high gain antennas are designed for three cell sectors, and employ using active antenna arrays with multiple beams and manifolds within each sector. 2.3.2.4 Multiple Antennas for Spatial Diversity Multiple antennas of the types described above, spaced several wavelengths apart, are used at the Base Station to provide spatial diversity, which helps to mitigate t e effects of multipath-inducεd Raylεigh fading εncountεrεd in typical mobilε PCS εnviro mεnts. Sincε rεcεivεd signals from antεnnas spacεd a few wavelengths apart fade indepεndently, a spatial diversity performance improvement is obtained. Tnis is done by selεcting thε bεst signal rεceived from multiple separated antεnnas in a flat fading multipath environment. Antenna spatial diversity also mitigates the effects of Frequεncy Sεlεctive fading, which degradεs link pεrformancε by distorting PN chip waveforms causing intersymbol interference. 2.4 Transmitter Power Output Characteristics 2.4.1 Mobile Hand Set Although thε FCC permits up to 2 Watts Effective Isotropic Radiated Power (EIRP) for the MS, Omnipoint's peak power input to the dipole antenna is 600 milliwatts, so the EIRP of the MS is a nominal 1 Wan, within the FCC requirεmεnt. Bεcausε of thε TDMA DD design of PCS2000, the average power delivεrεd to thε antεnna is only 9.36 milliwatts, permitting long duration between hand set battery recharging. The constant envelope characteristic of Omnipoint modulation techniquε pεrmits usε of an efficient non-linear output amplifier which can further rεducε banery drain. 2.4.2 Base Station Thε recent FCC Order permits up to 1500 Warts peak EIRP per RF channel for PCS Base Stations. Since Omnipoint's BS peak power input to its antenna is 2 Watts, the maximum permissible BS antenna gain (vertical plus horizontal) is limited to approximately 28 dB. Because TDD is used, the average BS power input to its antenna for a fully loaded TDMA frame is 1 Wan. 2.5 Modulation Charactεristics 2.5.1 Spread Spectrum Modulation of RF Carrier To produce the direct sεquεncε sprεad spεctrum (DSSS) characteristic of the PCS2000 RF signal, Omnipoint uses a form of continuous phasε shift quadraturε modulation (CPSQM), which providεs a constant amplirudε for thε εnvεlopε of thε modulatεd carriεr. Thε constant εnvelope of CPS QM pεrmits efficient non¬ linear RF power amplification (especially desirable for long Hand Set banery life), without re growth of modulation spectral sidelobes. By shaping the PN chip waveforms bεfore quadraturε modulation; all modulation sidεlobεs at frequencies more than one-half thε chip ratε away from the cεntεr frequency of the DSSS RF signal are aπenuatεd by at least 42 dB relative to the center frequency power level. Since the PN chip rate is 5 MHz, thε resulting DSSS signal spectral bandwidth is approximately 5 MHz (outside this bandwidth, all modulation spectral components are attenuatεd by > 42 dB). 2.5.2 M-ary Encoding of Basε Band Data DSSS convεyancε of information is accomplishεd by using multiple DSSS chip sequεncεs to M-ary encode the TDMA base band data 32-Ary modulation is provided by encoding each 5 bits of data as one of 32 orthogonal PN sequences, each of which is 32 chips in length. The use of32-Ary encoding of base band data with orthogonal PN sequences provides both spread spectrum processing gain against in-band interferes, and very power efficient, low threshold (Eb/No) reception. 2.6 TD MA/TDD System Charactεristics 2.6.1 Multiple Accεss Method Omnipoint uses a unique combination of TDMA, FDMA, and CDMA for multiple user access to the PCS network. Within a PCS cell Time Division Multiple Access (TDMA) is used. Although either Frequεncy Division Duplexing (FDD) or Time Division Duplexing (TDD) can be used for establishing 2-way links with a PCS system, Omnipoint has chosεn to use TDD, because it provides several operational and performance advantages relative to FDD, and it permits a less complex, lower cost implemεntation of both Hand Set and Base Station terminals. To provide greatεr arεa of coverage, or to provide greater capacity for densely populated regions, multiple cells or sectorized cells are deployed using Frequency Division Multiple Access (FDMA) with a frequency reuse factor of N = 3. Also, to permit multi-cell deploymεnts in a given region, Code Division Multiple Accεss (CDM is usεd for εach RF link to reduce co-channel interferencε bεtwεεn cεlls reusing the same RF carrier frequencies. 2.6.2 TDMA Frame and Time Slot Structure Omnipoint's TDMA/TDD framε and timε slot structurε is basεd on a ' 20 millisεcond polling loop for usεr accεss to thε RF link, as shown in Figurε 2.2. Thε 20 ms framε is equally divided betwεεn 32 potεntial full duplεx users within the cεll, and εach resulting 625 us time slot is capable of supporting an 8 kbps full duplex user. At the Base Station, the first half of the TDMA/TDD time slot (3 12. us) is allocated for the BS transmit function. During the second half, the BS receives from the Mobilε Station assignεd to that particular timε slot. At thε Mobilε Station, the MS rεcεives during the first half of the time slot, and transmit during the last half. After each TD A transmission from eithεr the Basε or Mobilε unit a small portion of εach time slot (designated TDD Guard Time) is allocated to allow the transmiπεd signal to propagate to a mobile recεivεr at thε maximum spεcifiεd distancε from the Basε Station (maximum cεll radius), and back again (approximatεly 10 us pεr mile, round-trip). This is necessary to prevεnt rεceived and transmitted TDD signals from overlapping at the Basε and Mobilε terminals. Also, a short timε intεrval (-9.6 us) at thε bεginning of εach timε slot is usεd to transmit a Power Control Pulse (PCP) from thε Mobilε Station which is usεd for sεvεral purposεs. First, it serves as a synchronization preambl or determining the beginning of -ary data symbols within the time slot. Sεcond, it servεs as a channεl sounding pulse to determine link propagation loss, and to servε as a mεasurεmεπt of link quality for Omnipoint's Power Control subsystem. Tnird, the. PCP is also usεd to cεtεrminε which of thε multiplε antεnnas to usε for the Omnipoint spatial diversity scheme. The PCP permits spatial diversity control to be updated during each TDMA time slot period. The Base Station transmits a Power Control Command (PCC) pulse, similar in length to the PCP, at the beginning of its TDD transmit period. The PCC pulse serves as a synchronization preamble for the MS receiver M-ary symbols, it also provides power control signal to adjust the MS power output level to a value just large enough to provide the required signal-to-noise/interference ratio at the BS, as determined by the quality of thε recεivεd PCP from the MS. TDMA Packet Structure The Omnipoint system can be used in either a Time Division Duplex (TDD) operation or in a Frequency Division Duplex (FDD) operation. The TDD format is shown below and described in detail in the Version 2T.X documentation. The Omnipoint Version 2T.X system uses a combination of TDMA and TDD in which an air slot is reserved for handset to base transmission and another paired air slot for base to handset transmission. Guard times are built into the system to allow for delays in processing, propagation over the air and transmission through the electronics/cabling of the system. The following is an illustration of an air slot showing the guard times between transmit and receive as shown in Figure 2-2 : Omnipoint's TDMA frame structure is shown in Figure 2- 6: The header in the packet identifies the base station or handset, packet type, link quality, and other information required by the system for efficient operation. An ISDN-like "D" channel format is provided in every packet for application-specific information. This information can be used for signaling, short message service (such as in GSM) , voice mail notifications, or other data messaging applications. At the present time, the D channel is available in its entirety to the user and is not used for any call processing or Omnipoint system information. Error correction algorithms are used with data transmission via the D channel to ensure delivery (and acknowledgment) of the information. Although Omnipoint technology can use either TDD or Frequency Division Duplex (FDD) within a call, the TDD design capability is generally required for use in unlicensed bands. FDD systems cannot operate in the unlicensed PCS bands because of the inability to separate transmit and receive bands adequately. 3.2.4. Data Rates Omnipoint views high speed data as a significant differentiating capability of PCS over conventional cellular services. As such, the PCS provider must be able to provide a form of "data on demand" service that allow higher data rates than conventional cellular technologies are capable of . To that end, Omnipoint provides the ability for the user to request bandwidth on call origination that is consistent with the application being used. For example, a mobile voice subscriber might require only an 8 kbps voice channel for a vehicular telephone call. On the other hand, a data user would have the ability to request multiple 8 kbps channels to provide 14.4 kbps or higher data traffic (with error correction providing an objective of 10 "δ error free transmission) . Further, an office user (using an unlicensed system with Omnipoint's CAI) might request 32 kbps voice for enhanced voice quality. The system secures the necessary bandwidth on call origination for the application desired. Omnipoint's system can provide up to 256 kbps full duplex (128 kbps full duplex per single handset due to the current processing limitations in the handset CPU, though this limitation will be removed in future handset CPUs) . Bulk transport of data is possible through this capability at up to 512 kbps in broadcast mode. This data rate far exceeds the current 9.6 to 19.2 kbps limitations of other wireless solutions. Omnipoint has designed the system around a nominal data rate of 8 Kbps per user. However, higher or lower rates are possible through the following acquisition schemes : Lower data rates (<8kbps) -the base station assigns the user a time slot in non-sequential frames allowing for rates of 4 kbps (every other frame) or lower. The picture below illustrates the use of time slots in non¬ sequential frames. SEE FIGURE 2-8 Higher data rates (>8kbps)-the base station simply assigns multiple time slots within a frame, allowing the user to secure multiples of 8 kbps up to the system maximum. The picture below illustrates the use of multiple time slots in a single frame. SEE FIGURE 2-7 2.6.3 TDMA Burst Symbol/Data Ratεs The TDMA/TDD data burst rate during transmission is dεtεrminεd by thε rεquirεmεnt to providε an 8 kbps digital voicε capability for 32 full duplεx usεrs pεr framε during thε 20 ms framε period. This requires a TDMA/TDD burst dat rate of 5 12 kbps. Becausε of thε Guard timε rεquirεmεnt of thε TDD mode of operation, and because of additional overhead bits rεquirεd for link protocols and control functions, thε actual Omnipoint TDMA burst ratε is 781.25 kbps. However, with the 32-ary encoding method used, the TDMA burst symbol rate i only 156.25 ksps. At a 5 Mcps DSSS chip rate there are 32 chips per burst symbol and 6.4 chips per burst bit. This provides a DSSS Processing Gain of approximately at -8 dB. 2.6.4 Variable Number of Timε Slots/Usεr By assigning morε time slots to onε of the users within a cεll, that usεr can communicatε at a highεr data ratε; e.g., by employing 4 time slots, the user terminal could operatε at a 32 kbps data rate, versus 8 kbps for one time slot. The Base Station, in a broadcast mode to all mobiles within its cell, can transmit at a data rate of 512 kbps. 2.6.5 TDD Featurεs Thε usε of Timε Division Duplεx (TDD) permits common antennas to be used for transmit and receive functions at both the Base and Mobile stations, without the need for antenna diplexers. Tnis is bεcause TDD utilizes the samε RF frequency for the transmit and receive functions, and because thesε functions are separated i time at each of the terminals. In addition to the resulting simplicity of the BS and MS terminal designs, use of the same RF frequency and antenna for both transmit and receive functions at the Base Station and Hand Set provides reciprocal propagation paths between the BS and MS terminals. This permits Orn__ipo_nt to use the channel sounding PCP transmitted by the MS to determine the two-way path loss between the BS and MS, and also to determine which of the spatial diversity antennas at the BS to use; bod. to receive from the MS, and to transmit to the Hand Set. TDD also permits Omnipoint to utilize a single Steered Phased Array antεnna at thε Basε Station for thosε deployment applications requiring a high gain, highly directional antenna. Therefore TDD provides a much simpler and very much mor cost effective design implementation than a simple CDMA or FDMA PCS system which would requirε simultaneous steεrεd bεams for εach mobilε usεr within thε cεll. 2.6.6 Systεm Timε and Frequency Synchronization Characteristics 2.6.6.1 Base Station and Base Station-to-Base Station Synchronization Thε Basε Station providεs thε basic TDMA loop timing strucrurε for its cεll or sεctor.. To maximizε PCS systεm throughput capacity, thε TDMA framε timεs for all Basε Stations within thε samε geographical area must be synchronized to begin transmissions within 6 microseconds. Omnipoint utilizes a GPS receiver at the Base Station Controller (and optionally at the BS) to genεratε the primary refεrεnce timing marker for the TDMA frame timing. Tnis marker is captured at the Base Station Controller evεry second and transmitted down the back haul lines to thε attachεd Basε Stations. This synchronization of Basε Stations within a givεn multicεll PCS dεploymεnt allows a Basε Station Controllεr to temporarily turn off any TDMA timε slot of a givεn cεll which may be interfering with a neighboring cell, and it also facilitates Time Slot Interchangε (TSI); i.e., switching an MS to a diffεrεnt timε slot if a currεnt timε slot is being interfered with by an adjacent cell using the same timε slot. 2.6.6.2 Base Station-to-Nεrwork Synchronization Thε primary data timing standard in a digital network backhaul system, such as Tl or ISDN BRI or PRl is the PSTN timing standard. To prevent data precession into over run or under run, the Base Station Controller and its Base Stations are synchronized ro the PSTN timing standard. 2.6.6.3 3ase Station-to-Mobilε Station Synchronization A synchronization preamble is transmitted at the beginning υfeach TDMA ti slot by both the Base Station and Mobile Station. The preamble is contained within the PCP at the MS, and it consists of a 48 PN chip sequence. When th preamble is received at the MS by a digital correlator (matched filter), the dig correlator outputs a triangular sync pulse which is only 2 chips in duration (4 nanoseconds), which is then used to synchronize the start of 32-Ary symbol detection process. At thε Basε Station, thε transmittεd sync preamble is contained within its Power Control Command (PCC) pulse, and it is also 48 chi in duration. The MS uses thε rεcεived sync preamble in the same manner to synchronize its 32-Ary symbol dεcodεr. Tne preamblε sync pulses (PCPs) received by the Base Station from thε Mobi lε Station arε also used to determine which of thε spatial diversity antennas to use for transmission and reception wit that Mobile Station during the next timε slot. Since non-coherent detεction is usεd by ihε BS and MS rεcεivers, they do not h to be phase-locked. However, the transmit and receive local oscillator frεquεnci of the 3S and MS must be conu-ollεd to within ÷l- 1 1 parts per million (ppm) o :ht opεrating tεmperarurε rangε, so as not to significantly dεgrade recεiver performance. Tne MS frεquεncy stability is permitted to vary < ÷\- 10 ppm, an thε BS stability requirement is an order of magnitude more stringent at ÷\- 1 pp 2.6.7 Mobile Access/Link Setup 2.6.7.1 Polling Loop Description A polling loop is comprised of 32 Time Division Duplexed (TDD) slots as shown in Fig. 2 - 3 . Each time slot is divided into two pans, a BS to M transmit interval and a MS to BS interval and is structured as sixty four Time Division Multiple Access (TDMA) time slots. Duplexing is accomplished by Time Division Duplexing each TDMA time slot pair. Tne slots are not numbered and there is no index associated with the polling loop. Slot synchronization is achieved solely by timing. The first part of a TDD slot is the 3ase Station (BS) to Mobile Station (MS) transmit frame and the sεcond part of a TDD slot is the MS to BS transmit frame. The BS initiates all transaction between the BS and MS. A Genεral Poll frame is how a MS acquires a co nεction to a BS. Any timε slot that is not seizεd By a MS contains a General Poll command in the BS to MS part. To acquire a slot, the MS responds to the Genεral Poll Response with a Genεral Poll Response. Tnε BS, upon rεcεiving thε Gεnεral Poll Rεsponsε, sends a Specific Poll Response. See Figure 2-3. Following signalling data exchanges, the BS and MS begin Bearer Traffic Exchange. 2.6.7.1.1 Polling Loop Design - Omnipoint Version 2T.X A 20 msec loop time is utilized in the Omnipoint Version 2T.X system for a total of 64 8 Kbps time slots simplex, or in a standard voice mode 32 8 Kbps full duplex users per base station RF channel. Figure 2-3 illustrates the loop design. See Figure 2-3 The Omnipoint system supports two types of polls that can be used for communications between the base station and the handsets within a cell. These comprise the following: General polls - general polls are used by the base station to allow any handset to communicate with a base station for the purpose of seizing an available air slot or to provide information about the base prior to beginning the handoff process. Specific polls - specific polls are used by the base station to solicit a response from a specific handset. This type of poll is used by the base station for finding and/or starting communication with a specific handset . Polls are used by the base station for establishing and maintaining communications with all of the handsets that are within its cell coverage area. 2.6.7.2 Gεnεral Poll Thε General Poll is a command sent from thε BS on any currεntly unoccupied sl At BS power-up, all 32 BS transmit slots contain a Gεπεrai Poll. Thε Gεnεral Poll is an invitation for any MS to sεizε thε timε slot. From a BS software point of viεw thε information in thε transmit framε hεadεr that dεfinεs a Gεnεral Poll is a bit that signifiεs that this is a poll type frame, a bit that signifies that the BS is the originator of this frame, command bits that signify that this is a Genεral Pol and a basε ID in the data portion of the frame. When a MS wishes to seizε a timεslot, it receives a General Poll in an available time slot and responds, in thε MS to BS part of thε timε slot, with a Gεnεral Poll Rεsponsε. From thε BS software point of view the information in the Geπεral Poll Rεsponse header is a bi signifying that this is a poll type framε, no transmission εrror bit sεt, and the MS ID (PID) in the data portion of the frame. Upon recεiving thε Gεnεral Poll Response, the BS transmits a Specific Poll to thε MS. Should more than one MS respond to a Gεnεral Poll in a particular time slot, the collision and subsequεnt no rεsponsε from the BS will causε the involved MS's to back-off for a calculated time interval beforε attεmpting to sεizε a timε slot via a Gεneral Poll and General Responsε. Thε back-off algorithm usεs thε MS ID and thεrεfore each MS will back-off for a different length of time. 2.6.7.3 Specific Poll The Specific Poll is a command sent from the BS to the MS in response to a General Poll Response from a particular MS. Seε Figure 2-3. The General Poll Response contains the MS's PID. From a BS software point of view the information in the transmit framε header that defines a Specific Poll is a bit that signifies that the BS is the originator of this frame, command bits that signify that this is a Specific Poll, and the MS PID in the data portion of the frame. Tnis PID is issued as a part of thε Specific Poll command so that only thε originating MS will receive the Specific Poll. Upon rεceiving a Specific Poll, a MS will respond with a Specific Poll Response in the MS to BS transmit interval of the time slot. From the BS software point of view the information in the Specific Poll Response header is a bit signifying that this is a poll type frame, no transmission εrror bit sεt, and the MS IS (PID) in the data portion of the framing matching the PID sent out in the Specific Poll. When the BS receives the Specific Poll Responsε, it goεs through a signaling traffic εxchange with the MS, leading dirεctly to Bearer Traffic Exchange. 2 . 6 . 7 . 1 . 2 Channel acquisition occurs whenever a handset needs to access a base slot or requires resynchronization with a base slot . During channel acquisition the handset begins to search for an available base station in its general vicinity by listening for a common signaling poll on any time slot from any possible frequency. Once a base is located with sufficient signal strength and adequate load available, the handset instantaneously seizes an air slot in response to the base station's general poll and the handset provides the base with ID and user information. The base station then transmits a specific poll for that handset to commence communications. At this point, that time slot is removed from being in common signaling mode and the handset and base station are ready to go into traffic mode and begin communications on that time slot. Collisions, during time slot acquisitions, are resolved by an 802.3-like backoff procedure. The traffic mode in thε Omnipoint system occurs after a base station and handset have established a transmission path with the appropriate allocation of air slot resources for the service being supported. In the traffic mode, two basic types of messages can be supported. These include: Normal or bearer traffic - bearer traffic consists of the actual information that is being carried by the wireless link, either a voice link or some other form of digital information. Omnipoint supports a bearer channel of 128 bits per frame in each direction (256 bits per frame full duplex) . Control traffic - control traffic provides for link specific data messaging or call control information. In extremely rare instances, two users on the same time slot in different cells but on the same frequency may encounter propagation characteristics in which the spatial and code separation are insufficient to prevent bit errors and thus the users begin to experience degradation of their radio links. In these cases, the Omnipoint system performs a Time Slot Interchange (TSI) wherein one or both of the conflicting handsets are assigned different time slots within its base station to eliminate the collisions between the two users. This is the time domain equivalent of dynamic channel allocation and the system either assigns a vacant time slot to the handset or switches the handset's time slot with that of another user in the same cell which is geographically removed from the interference. The effect is the removal of interference to the users originally experiencing interference due to poor location specific C/I ratios. 2.6.7.4 Bearer Traffic Exchange Once the MS has seizεd a timε slot and been validated (D- channεl data), thε εxchangε bεtwεεn thε MS and BS lεads to Bεarεr Traffic Ξxchangε (B-channεl data). Bεarer Traffic can be voicε, error-controlled data, or non-error controlled (raw) data. From the BS software point of view the information in the Bεarεr Traffic header is the absence of a bit signifying that this is poll type frame, no transmission error bit set, and no bit signifying signaling data. Each TDD slot can be configured with the majority of the slot timε givεn to thε BS to MS dirεction, thε majority of thε slot time given to thε MS to BS dirεction, or symmεtric distribution giving fifty percent of the time to both BS and the MS. Typically voice traffic utilizes the bearer channel symmetrically as eithεr εnd of thε link may send voice traffic. In a data exchange, typically more data is sent in one dirεction and less in the other. For instance, if fax data werε bεing sεnt to a MS, a highεr data ratε would be advantageous in the BS to MS direction. In this case the majority of the TDD slot time is given to the MS to BS link. A particular BS to MS and/or MS to BS may also be assigned multiple slots within a single polling loop. Tnis can dramatically increasε thε bearεr channεl data every second or every fourth polling loop, the data ratε is cut significantly. This tεchnique is useful for instrument telεmεtry data, fax and vidεo control back channel, etc. 2.7 Power Control Method Although the Omnipoint method of Time Division Multiple Accεss (TDMA) does not require the strict control of transmitter RF power output nεcessa y to resolve the "Near-Far" problem εxperiencεd by CDMA PCS systems, PCS2000 doεs utilizε a propriεtary method of controlling transmitted RF power level. This is done to reduce Mobile Station battery consumption and to minimize interfεrεncε to othεr cells, which may be operating on the same or adjacent RF channels. By maintaining MS transmitter power at the lowest value required for sufficient MS- to-BS link quality, interference with nearby OFS users is also minimized. 2.7. 1 Control of Basε Station Power Output Sincε thε Base Station can communicate with up to 64 Mobile Stations within it cεll, each of whose distance from the BS can vary from near zero up to the radiu of the cell, it may not be practical to control the BS transmitter power to maintai near-constant received power level at each MS during each time slot This could requirε a largε changε (>40 dB) in BS transmit power during each time slot (625 μs) of the TDMA frame. Omnipoint provides BS power control, averagεd ovεr longεr timε interval, and is investigating the various altemativεs to utilizε BS powεr control on a slot-by-slot basis to minimizε cell-to-cell and cell-to-OFS intεrfεrencε.. 2.7.2 Control of Mobilε Station Powεr Output To pεrmit RF channεl reuse in nearby PCS cells, reducε interference with OFS users, and conserve battery power in the handheld units, Omnipoint provides adaptive power control of the Mobile Station transmitters within each PCS cell using a proprietary Power Control Pulse (PCP). In Version 2T.X, the PCP is transmitted by the MS in its assigned TDMA timε slot just bεforε thε BS transmits to that MS in its associatεd TDD timε slot. This PCP providεs the BS with a mεasurεmεnt of the MS-BS path transmission loss and link quality, and serves as the basis for a Power Control Command (PCC) transmitted from the BS to thε MS. Thε PCC causεs the MS to change its output power in minimum steps of 3 dB, until the qualify of the PCP received by the BS is above an acceptable threshold. Tnis simple method of controlling MS transmitted power minimizes ' potential intεrcεll intεrferencε, and also intεrfεrence with nearby OFS usεr rεcεivεrs. In some TDMA systems, the latency of thε polling loop signals prevent the use o closed loop power control. However, with Omnipoint's Version 2T.X TDD TDMA design approach, the elapsed time for transmission of the PCP, the respoπsε by the MS to the PCC from the BS, and the next MS bearer transmission burst is less than 500 us— less than 2.5% of the frame time. Because of its fast responsε timε, Omnipoint's Power Control algorithm acts faster than the signal changes duε to small scalε multipath fading and shadowing, and helps to mitigate any performance degradation caused by thesε effects. The BS can also use the PCP information to measure the propagation time to each MS within its cell. This provides an estimate of the range from the BS to each MS. For 911 support, if the PCS service operator invests in the necessar software, c. handset could pro vide PCP signet ' s to multiple BSs j ' or c rough, location estimate in emergency situations. 2.S Di g itized Voice and Data 5i _T;_!_ 2.3. 1 Digitized Voice S ignal S tructure 2.8. ! . ! Speech Coding Algorithms Ove rview The speech coder specified herein supports the Omnipoint PCS system, providi switchable ratε (S Kbps/ 15 Kbps/24 Kbps 32 Kbps/^O Kbps ό- Kbps) speech compression to allow- selectable channel capacity or voice quality. Tne speech coder will execute on a DS? chip or equivalent device. In the initial implementation, the algorithm will execute on a 2 — - i fixed-ooiπt DS?. In thε initial implementation, the system diagram in Figure 2-4 applies to both ends of the Omnipoint over channel. In this case both the Mobile Station (MS) a the Base Stations (BS) will utilize the same DSP algorithms and interfaces . In subsequent implementations, the 3S and MS architectures will cha from that shown in Figure 2-4. Referεnces to future implementation requirements are made throughout this specification and the speech coder design should be flexible enough to support these future implementatio options. Reference Documents CCITT G.71 1 Pulse Code Modulation (PCM) of Voice Frequeπciεs. CCITT G.726 Gεneral Aspects of Digital Transmission Systems; Tεr niπal Equipmεnt' 40, 32, 24, 16 Kbits/s Adaptivε Differential Pulse Code Modulati (ADPCM). EIA/IS- 19 Recommended Minimum Standards for 800-MHz Cellular Subscrib Units, Paragraph 10 - DTMF Signaling . Functional Description Compression Modes The speech coder shall have four compression modes selectable via host command. 1) Persona! Communication System CELP (PCS CELP) - 8 Kbps 2) ADPCM (CCITT G.726) - 32 Kbps, 24 Kbps, and 16 Kbps 3) ADPCM (CCITT G.726) - 40 Kbps 4) μLaw PCM (CCITT G.71 1 ) - 64 Kbps (pass through) The speech decoder will receive formatted and synchronized data frames from the Spre Spectrum Modem chip and will generate 64 Kbps PCM voice data to the CODEC using either t PCS CELP algorithm, one of the ADPCM (G.726) algorithms or the PCM pass throu algorithm. The speech encoder will receive 64 Kbps PCM data from the CODEC and compre this PCM signaling using the algorithm selected by the host controller (64 Kbps PCM 32/24/1 Kbps or 40 Kbps ADPCM, or PCS CELP). The same compression mode vvill be used for bot encode and decode operations. Data passed to and received from the speech coder will b synchronized with timing signals provided from the Spread Spectrum Modem and will conform t the framing structures defined in this specification. External control inputs will be provided t instruct the speech coder to implement muting or soft decay (interpolation) of the voice outp during periods of degraded channel conditions with unacceptably high error rates (i.e. durin blockage or hand-off conditions). Status outputs will be provided indicating speech cod performance and EEC error count (if required). Additional Capabilities Additional capabilities in the speech coder include the following. These capabilities ar listed in desired priority of implementation. a) Interpolate and Mute Functions to provide graceful audio degradation in the presenc of errors. b) Error correction coding (if required) to support reliable voice communication acros the communication link when operated in PCS CELP mode. c) Near-end echo cancellation. A short path echo canceler will be incorporated in compression modes to minimize the effect of near end echoes. d) DTMF tone gεneration and detεction. e) Programmable level setting for the receive, transmit and sidetone loop voice pa under host control. f) Provide reasonable reproduction of Music-on-Hold. g) Voice activity detection / Comfort noise generation. h) Echo suppresser disable tone detection (for fax and data modems). ■ i) Voice encryption/decryption. Note: These additional capabilities may be req uired in BS speech coders, speech coders or both. In the initial implementation, the PCS CELP algorithm uses only 7.2 Kbps of the availa 8 Kbps bandwidth. The remaining 16 bits per frame are reserved for future uses. These bits currently reserved for: 1) Voice/Pitch Enhancement. 2) Forward Error Correction (EEC). 3) In-band signaling/DTMF. 4) In-band Voice Activity Detect (VAD). 5) Music on Hold. Interpolate Function The speech coder, when operating in any of its compression modes, shall provide interpolate function to soften the effect of errors. An INTERPOLATE control register bit w indicate to the speech coder that the previous frame of voice data was received in error by t Spread Spectrum Modem. The speech coder will output its predicted voice pattern to t CODEC instead of the data received from the modem. The speech coder shall be capable receiving up to 4 consecutive bad frames (i.e. INTERPOLATE bit set) and will output increasingly attenuated version of its predicted voice pattern for each consecutive error. Wh the number of consecutive bad frames exceeds a threshold of 4, the speech coder shall mute i output to the CODEC. The reception of a single good frame, indicated by the INTERPOLA bit cleared in the control register, shall immediately reset the speech coder out of interpolate mo (including mute conditions created by the interpolate function) and the good frame of voice w be decoded and sent to the CODEC. Decoded data only will be affected by this mode. Encod data will continue to be sent uninterrupted to the modem side of the DSP. Mute Function The speech coder, when operating in any of its compression modes, shall provide a mu function to generate silεncε whεn voice data is not being transferrεd by thε Spread Spεctru Modem. A MUTE control register bit shall force the speech coder to output silence to t CODEC instead of the data receivεd from the modem. The recεptioπ of a siπglε voice fram indicated by the MUTE bit clearεd in the control register, shall immediatεly rεset the speech cod out of mute mode and the frame of voice will be decoded and sent to the CODEC. Decoded da only will be affected by this mode. Encoded data will continue to be sent uninterrupted to t modem side of the DSP. Echo Cancellation The details of echo cancellation operation will be presented in future documentation. DTMT Toπe Generation and Detection The speech coder shall provide the capability to generate and detect up to 3 1 possible ton including the 12 DTMF signals as defined in ELA/IS- 19. Other candidates for tones to generated include a 1 KHz test tone; dialtone, busy and ringback tones. A lower level DTM signal will be sent as a sidetone via the CODEC interface. The DTMF signal will need to coded and transmiπed in-band via the modem interface. The generator will be under host contro Programmable Level Control Figure 2-5 shows a rough block diagram of voice paths through the speech coder an indicates those points where programmable level control is required. The sidetone path loop PCM data from the CODEC back to the CODEC. The transmit path consists of PCM data whic is encoded and output to the Spread Spectrum Modem. The receive path consists of encode data from the Spread Spectrum Modem which is decoded and output as PCM data to th CODEC. The receive level control will also control the level of DTMF tones sent to the CODE Appropriate level settings will be input to the speech coder from the modem or ho microcontroller via the control registers. Voice Activity Detection / Noise Comfort Generation The details of VAD and comfort noise generation will be provided in subsequent submissions. Echo Suppresser Disable Tone Detection The details of echo suppresser disable tone detection will be provided in subsequent submission Voice Encryption Decryption The details of voice encryption decryption will be provided in subsequent submissions. Interface Requirements Modem Interface Physical Interface and Timing The interface between the speech coder and the spread spectrum modem is based synchronous bi-directional serial data transfer. The data transfer is synchronized by timing sign received from the modem. Compressed voice is clocked in and out at a rate of 8 Kbps, 16 Kb 24 Kbps, 32 Kbps, 40 Kbps or 64 Kbps, depending on the mode of operation (PCS CE 32 24/16 Kbps or 40 Kbps ADPCM or PCM respectively). The DSP frame size shall be 20 m to match the PCS superframe size of the Omnipoint system. The data rate is guaranteed o each 20 msec period (e.g. for PCS CELP, the DSP will receive and transmit 20 bytes compressed voice every 20 msec, 32 Kbps ADPCM = 80 bytes, 0 Kbps = 100 bytes and PCM 160 bytes). Within the 20 msec frame however, data will be transfeιτed to and from the DSP packets as it is rεceivεd and sεπt by thε modem. Each packεt will consist of 20 bytes of voi (also called a speech frame) followed by 12 bytes (subject to change) of control/stat information. The 12 bytes following the voice in the receive direction shall be control informatio from the mode . The 12 bytes following the voice in the transmit direction shall be statu information from the DSP. An additional SYNC signal will be sent by the modem to the speech coder to indicate th the modem is in sync, to indicate the first valid data bit of a new frame and to reset the speec coder's buffer pointers to the beginning of its buffer. The interface between the speech coder and the Spread Spectrum Modem includes th following signals TXD - Serial Transmit Data output, clocked by the rising edge of the CLK signal. RXD - Serial Receive Data input, sampled by ihe falling edge of the CLK signal. CLK - A single clock input signal to be used both for the receive and transmit data. Th clock shall be gated on and off by the modem as required to send the 20 + 12 byt packets of compressed voice and control/status. The clock rate shall be 2.0 MH (nominal). In the initial implementation, the clock rate shall be 2.048 MHz Changes in this clock rate shall not affect DSP algorithm operation. An interna interrupt shall be generated after each byte of data (8 CLK transitions) which wil cause the DSP to read the byte of data just received and load the transmit shi register with the next byte to be transmitted. SYNC - An input signal received from the modem to indicate that the modem i synchronized. The SYNC signal also indicates the beginning of a new frame o data. SYNC shall be an active high pulse which is one period of CLK in duration When the modem is synchronized and is transferring voice data, the rate of SYN shall be 50 Hz (every 20 msec). SYNC shall be connected to an external edg sensitive interrupt of the DSP. A negative transition on SYNC will cause th speech coder to reset its buffer pointers to the beginning of its buffers. Note: In the initial implementation, the modem interface shall utilize the serial interface just described. In subsequent implementations, the encoded voice and control/status information may be sent and received by a host microcontroller via a parallel host interface port. In either case, the compressed voice as well as control/status information will be sent over a single interface- Protocol and Data Definition Each 20 msec frame will be rr.2de up of one, four, five or eight packets (20 bytes comprεssεd voice and 12 bytes of control/status) depending on the compression mode sεlεct Where applicable, the control function (i.e. Mute and Interpolate) shall be applied to the previ 20 bytes of compressed voice in the packεt, rather than being appliεd for thε entire 20 m frame. Notε that in thε initial implementation 24 Kbps and 16 Kbps ADPCM arc supported optional for final implementation. Six different data framing structures axe to be suppoπed by the speεch coder; one for PCM pass through, four for ADPCM compression and one for PCS CELP. For PCM, the voicε bit streams will be identical to those defined in the CCITT G.71 1 standard. For ADPCM the voice bit streams will be identic to those defined in thε CCITT G.276 standard. For PCS CELP compression, the voice stream will include the CELP parameters with the significant bits protected by an error correction code (if required). Tne num of speech frames per PCS superframe is defined for each compression mode as follows. a. PCS CELP The PCS CELP frame will be 160 bits and will convey 20 msec of speech. The frame si will correspond to the Spread Spectrum Modem's TDMA slot size 625 msec. Each PCS superframe will include 2 speech frames per link (one for transmit and one for receive if no VAD). b. 2 Kbps .ADPCM Frame structure and data formatiiπg shall be in accordance with the CCITT G.7 Specification. No error correction bits will be included in the frame. The .ADPCM frame size sh be 125 μsec (8 KHz) and the overall number of oils in each frame shall be 4. The Spre Spectrum Modern's frame size (TDMA slot size) shall be 160 bits. Each PCS superframe ( msec) will include 8 160 bit spe ch frames per link (4 for transmit and 4 for receive if no V.AD). c. 40 Kbps ADPCM Frame structure and data formatting shall be in accordance with the CCITT G.7 Specification. No error correction bits will be included in the frame. The ADPCM frame s shall be 125 μscc (8 KHz) and the overall number of bits in each frame shall be 5. The Spre Spectrum Modem's frame size (TDMA slot size) shall be 160 bits. Each PCS supcrfrarne ( msec) will include 10 160 bit speech frames per link (5 for transmit and 5 for receive if no VAD d. 64 Kbps PCM Frame structure and d2ta formatting shall be in accordance with the CCITT G.7 Specification. No error correction bits will be included in the frame. The PCM frame size sh be 125 ' μsec (8 KHz) and the overall number of bits in each frame shall be 8. The Spre Speαrum Modem's frame size (TDMΛ slot size) shall be 160 bits. Each PCS superframe ( msec) will include 16 160 bit speech frames per link (8 for transmit and 8 for receive if no V.AD Note again that 16 Kbps and 24 Kbps ADPCM are supported but optional in the initial version. CODEC Interface Physical Interface and Timing The speech coder connects to a standard PCM CODEC via a synchronous bi-directio serial interface. The data transfer is synchronized by timing signals received from the mod The same clock and frame synchronization signals will be used for transmit and receive. frame (word) rate shall be 8.0 KHz nominal, with 8 bits per word for an overall full-duplex d rate of 64 Kbps. The data to and from the CODEC will be μLaw encoded. The CODEC interface will include the following signals and is shown in Figure 4. In initial implementation, the CODEC interface will utilize the SSI port of the DSP. STD - Serial Transmit Data output, clocked by the rising edge of the SCLK signal. SRD - Serial Receive Data input, sampled by the falling edge of the SCLK signal. SCLK - A clock input used for both receive and transmit data. The clock rate shall be MHz (nominal). In the initial implementation, the clock rate shall be 2.048 M Changes in this clock rate shall not affect DSP algorithm operation. An inte interrupt shall be generated after each byte of data (8 SCLK transitions) which cause the DSP to read the byte of data just received and load the transmit s register with the next byte to be transmitted. FS - A frame synchronization pulse input, used for both receive and transmit data. shall be an active high pulse which is one period of SCLK in duration. The FS r shall be 8.0 KHz (nominal). Eight bits of data shall be transferred after each FS. The CODEC interface will be synchronized every 20 msec by the SYNC signal from t modem. Microcontroller Interface In the initial implementation, a microcontroller interface is not planned. However in subseque implementations, a microcontroller interface may be utilized to load selected DSP algorith (depending on the compression mode selected). A microcontroller interface may also be used an alternate parallel interface for the serial Modem interface. The speech coder shall be able transfer compressed voice and control/status information via a byte wide host interface in additi to the previously described serial interface. Only one of the interface options will be used at given time. Physical Interface and Timing For the DSP implementation of the speech coder, the microcontroller interface shall utili the byte-wide host interface port. Physical interface and timing details will be provided subsequent submissions. Protocol and Data Definition The data definition for the mode interface via a parallel host port shall be the same that described in Sections 3.1 Modem Interface and 3.4 Control/Status Definition. Th compressed voice and control/status information will be stored in the same buffer locations those used by the serial modem interface. For algorithm loading via the parallel microcontrolle interface, see Section 3.5. Control/Status Definition Control/Status Register Locations Each speech frame of compressed voice across the modem interface is followed by 12 bytes of control or status information depending on the direction of data flow. The following tables indicate the relative locations of the control and status registers within each packet. Compressed Voice Interface (Modem to DSP, i.e. Rx Voice + Control) Bytes 0- 19 Compressed Voice (20 bytes) Byte 20 Mute/Interpolate Control Register Control Register # 1 Byte 21 Compression Mode Control Register Control Register #2 Byte 22 Tone Detection Control Register Control Register #3 Byte 23 Tone Generation Control Register Control Register 0A Byte 24 Transmit/Sidetone Level Control Register Control Register #5 Byte 25 Receive Level Control Register Control Register #6 Bytes 26-29 Unused Control Registers #7-10 Byte 30 Sync Word S I Control Register #1 1 Byte 3 1 Sync Word #2 Control Register #12 144 Compressed Voice Interface (DSP to Modem, i.e. Tx Voice + Status) Bytes 0- 19 Compressed Voice (20 bytes) Byte 20 Unused Status Registεr #1 Byte 21 Compression Mode Status Registεr Status Rεgister #2 Byte 22 Tone Detection Status Register ' Status Rεgister #3 Byte 23 Tone Generation Status Register Status Register #4 Byte 24 Voice Detect/FEC Status Register Status Register #5 Bytes 25-29 Unused Status Registers #6- 10 Byte 30 Sync Word # 1 Status Register # 1 1 Byte 3 1 Sync Word #2 Status Register #12 The following is a bit by bit definition of all the control and status bytes defined for the sp coder. Mute/Interpolate Control Register (#T) MIC MUTE: Mute the output to the Spread Spectrum Modem starting with the n frame. 1 - Mute 0 - Normal Operation Note: MIC-MUTE effects the encode operation only. Decoded data will continue to sent uninterrupted to the CODEC. MUTE: Mute the output to the CODEC for the preceding 20 bytes of voice. 1 - Mute 0 - Normal operation 145 INTERPOLATE: Indicates that the preceding 20 bytes of voice to the decoder was receiv in error by the Spread Spectrum Modem. The Interpolation algorit should be applied to this voice. 1 - Interpolatε for thε prεcεding 20 bytεs of voice 0 - Normal Opεration Note: All Control Register bits shall be cleared (0) following a reset. Compression Mode Control Register (#2) ECE: Echo cancelcr enable bit 1 - Enable 0 - Disable LPB: Digital loop back bit: 1 - Internally loopback modem interface (compressed voice) data 0 - Normal operation MODE 1.MODE0: Select data rate and speech compression type.: 0,0 - PCS CELP 0, 1 - 32 Kbps ADPCM 1 ,0 - 40 Kbps ADPCM 1 , 1 - Pass through 64K PCM Note: The speech coder always powers up in PCS CELP mode. Note: All Control Register bits shall be cleared (0) following a reset. Note: 16 Kbps and 24 Kbps ADPCM are supported but not implemented in the above mode selection. Tone Detection Control Register (#3) 146 DTMF Detection Control. Currently unused, reserved for fu :xpansion. Note: All Control Register bits shall be cleared (0) following a reset Tone Generation Control Register (#4) DTMF4-0: ' DTMF generation command. Generate the selected toπe(s) starting with the frame. Note: All Control Register bits shall be cleared (0) following a reset. Traπsmit/Sidetone Level Control Register (#5) 148 TX3-0: Transmit Level Control. Apply the gain setting to encoded data being sent t Spread Speαrum Modem. 0000= OdB 0001 =÷] dB 0010 = +2 dB 0011 =+3 dB 0100 = ÷4dB 0101 = +5 dB 0110 = ÷6dB 0111 =+7 dB 1000= 1111 = undefined ST3-0 Sidetone Level Control. Apply the attenuation setting to 64K PCM data looped from CODEC input to CODEC output. 0000 = Infinite attenuation 0001 =-21.5dB 0010 = -18.0dB 0011 =-15.0dB 0100 = -13.5dB 0101 =-12.0dB 0] 10 = -10.5 dB 0111 = -8.5 dB 1000- 1111 = undefined Note: All Control Register bits shall be cleared (0) following a reset. Receive Level Control Register (06) RX7-0: Receive Level Control. Apply the following gain setting to decoded d being sent to the CODEC. Note: All Control Register bits shall be cleared (0) following a reset. Sync Word #1 (Control/Status Register #11) Synchronization Word #1. Synchronization Words are provided in both control and sta data streams to allow for modem speech coder synchronization in system implementations wh an external SYNC interrupt is not available. A unique pattern will be assigned to the Sync Wo registers which will be detected by the speech coder. The Sync Words and the external inte accomplish the same function. Sync Word # 1 = C3 hex. Note: All Control Register bits shall be clearεd (0) following a rcsεt. Sync " Word #2 (Control/Status Register #12) Synchronization Word #2. Synchronization Words are provided In both control and st data streams to allow for modem/speech coder synchronization in system implementations w an external SYNC interrupt is not available A unique pattern will be assigned to the Sync W registers which will be deteαed by the speech coder. The Sync Words and the external inter accomplish the same funαion. Sync Word #2 = A5 hex. Note: All Control Register bits shall be cleared (0) following a reset. Compression Mode Status Register (#2) ECE: Status of current echo canceler enable bit: 1 - Enable 0 - Disable LPB: Status of current digital loop back setting: 1 - Internally loopback modem interface (compressed voice) data 0 - Normal operation MODEl,MODE0; Status of current data rate and speech compression type.: 0,0 - PCS CELP 0, 1 - 32 Kbps ADPCM 1 ,0 - 40 Kbps ADPCM 3 , 1 - Pass through 64K PCM Note: The speech coder always powers up in PCS CELP mode- Note: All Status Register bits shall be cleared (0) following a reset. Note: 16 Kbps and 24 Kbps ADPCM are supported but not implemented in the ab modes. Tone Detection Status Register (#3) DTMF Deteαion Status. Currently unused, reserved for future expansio Note: All Status Register bits shall be cleared (0) following a reset. Tone Generation Status Register (04) DTMF4-0: DTMF generation status. Echoes the status of the tone generati command. Voice Detect FEC Status Register (#5) FEC: Forward error correαioπ flag (if required): 1 - Error was corrected in previous frame 0 - No error was correαed in previous frame. VODET: Voice Detection (future option): 1 - Voice deteαed in previous frame. 0 - No voice deteαed in previous frame. Note: All Status Register bits shall be cleared (0) following a reset. DSP Algorithm Loading The DSP shall be capable of loading thε spεech codεr algorithms from a bytε-wide εxtε EPROM or from a host microcontroller via a byte-wide host interface port. In either case, speech coder software shall contain a bootloader function to load the appropriate algorith into fast internal and external RAM and execute them. In the initial implementation, the DSP will be loaded from a byte wide EPROM conneαed to DSP's external memory bus. This is referred to as stand-alone mode. In subsequ implementations, the DSP algorithms will be loaded by a host microcontroller via the byte w host interface. To ease external RAM requirements, it is envisioned that only the sele compression mode algorithm and applicable additional capabilities will be loaded. The DSP be reloaded via the host microcontroller each time a different compression mode is seleαed. Main Clock The speech coder device shall operate at a maximum nominal frequency of 40 MHz. operating frequency shall be generated by the DSP from an external 50% duty cycle clock rat 16 KHz using the multiplication capability of the built in PLL. The DSP shall have a maxim performance of 20 MIPS at this clock rate. Performance Requirements PCS CELP Speech Coder a) Input sampling rate: 8.0 KHz (nominal) b) Input frame length: 20 msec c) Output frame size: 160 bits compressed voice ÷ 96 bits control/status d) Output frame rate: 50 frames/second c) Speech quality: very good quality @ BER < 10 '3 good quality @ 10 '3 < BER < 10 " * acceptable quality @ 10 " * < BER < 10 '3 f) End to end delay: max. 80 msec g) Interpolation performance: The interpolation parameters shall be set to roughly yield the following audio degradatio levels: ]% Frame Errors - barely noticeable audio degradation 3% Frame Errors - some minor degradation but voice quality is st acceptable 1 1% Frame Errors - Speech coder generates full mute ADPCM Speech Coder ADPCM coding performance shall be in accordance with the CCITT G.726 Specification The maximum delay introduced by the algorithm implementation should be less than milliseconds. Echo Canceler a) Canceler's echo path: max. 5.5 msec. b) ERLE: min. 30 dB DTMF Generation a) The nominal frequenciεs and the frequency stability shall be in accordance wit specified rεquirεments in EIA/IS- 19. b) The DTMF signal level will be TBD. c) The DTMF sidetone will be fed back at a level determined by the receive gain control setting. d) The DTMF signal duration will be host controllable in units of a frame. DSP Bandwidth The speech coder algorithms shall utilize TBD of the available DSP bandw (approximately TBD MIPS). Software Characteristics Control/Status Software Interface Data received over the compressed voice interface from the modem to the DSP cont compressed voice together with control information to the speech coder. Likewise, transmitted from the DSP to the modem contains compressed voice together with st information from the speech coder. Twelve bytes of control and status information are sent along with every 20 bytes of compres voice information. For CELP, 20 bytes of compressed CELP data (corresponding to 20 mse speech) are sent at "time 0", followed by 12 bytes of control information that apply to the s 20 msec speech frame. At time t=20 msec, 32 more bytes are transmitted. A similar proc occurs in the reverse direction, with the difference being that the control information is repla by status information. Thus for 8 Kbps CELP, these 32 byte packets are transmitted once ev 20 msec. Note that for higher bit rate algorithms, they are transmitted more frequently. For Kbps, there are 4 32-byte packets every 20 msec. For 40 Kbps, there are 5 32-byte pac every 20 msec. For 64 Kbps, there are 8 32-byte packets every 20 msec. However the pac rate for higher bit rate algorithms is not guaranteed to be uniform (i.e. for 32 Kbps, the pac rate will not be 5 msec). These packets are transferred as required by the modem, (note: 16 K and 24 Kbps ADPCM are supported but optional for implementation. See Section 3.4 for control/status definition and relative locations of the control/status b within the frame. Speech Coder Buffering As described in previous seαions, the uncompressεd voicε intεrface of the PCS CELP Spe Coder is via the Synchronous Serial Interface (SSI) of the DSP. In the initial implementation, compressed voice interface is via the Serial Communications Interface (SCI) of the DSP. PCS CELP speech coder software interfaces to both the uncompressed and compressed vo data streams by means of double buffers. g . 2 - 9 shows the Speech Coder buffer structure and associated signal flow in the direαion speech decompression. Compressed speech is written into the SCI buffers and operated upon the compression algorithm in the internal Work Buffer. The decompressed speech output written into the SSI Buffer. Uncompressed speech is then "spoken out" of the SSI Buffe Speech compression has a similar set of buffers and is essentially the reverse of this process. Ea of the three SSI Buffers is 160 bytes long, for a total buffer length of 480 bytes (only the 8 MS of each 24-brrword are used). Each of the SCI buffers shown correspond to 20 msec of real ti (except for the work buffer), regardless of the buffer size or the compression algorithm in u For example, for CELP synthesis, the SCI Buffers are each 20 bytes long, for a total buffer len of 40 bytes. SSI Buffers A, B, and C are initially filled with all zeroes. At time t=0, SCI Buffer begins to fill with 20 bytes (160 bits) of CELP data, while SSI Buffer A is being "spoken". time t=20 msec, SCI Buffer A is full of these 20 bytes and SSI Buffer A has "emptied". S Buffer A is then copied into the Work Buffer. At this time, decompression begins upon the W Buffer contents, with the uncompressed data being placed into SSI Buffer C. Note that while S Buffer C is being filled, SSI Buffer B is being spoken and SCI Buffer B is being filled with n compressed voice. A similar process occurs in the reverse direction for speech compression. Note that for PCM and ADPCM the SCI buffer lengths still correspond to 20 msec of real ti However, for these algorithms, the Work Buffer length corresponds to a shorter period of ti For example, for 40 Kbps G.726 ADPCM the Work Buffer length corresponds to 4 msec of r time. This is due to the fact that for each algorithm the compressed voice is "packetized" into bytes of compressed voice and 12 bytes of control/status information. Regardless of the compression algorithm used, the SCI double buffers must still be 20 msec ea in length because of the over-air framing structure. 2.S.1.2 Variable Rate Speεch Coding VAD (Voicε Activity Dεtεction) control of thε voice transport mechanism is specifically supported in the Omnipoint CA . Utilizing thε VAD algorithm in the vocoder the CAI provides bandwidth turn around servicεs allowing ( for εxample) the 8 kbps vocoder algorithm to operatε ovεr thε C I link at only 4 kbps, thus allowing thε potεntial for doubling thε maximum number of usεrs pεr RE channεl (ε.g. up to sixty- four VAD 8 kbps usεrs). 2.8.2 Data Signal Structures 2.8.2.1 Variable Data Ratεs Overview PCS2000 has beεn dεsignεd to sεrvε as an efficient and flexiblε data conduit for a myriad of data, vidεo, multi-mεdia and broadcast applications. Thε dεsign allows ratεs greater than or less than the basic 8 Kbps rate to be provided to the end user. Tne ovεr-thε-air protocol provides 160 bearεr bits pεr slot pεr 20 millisεconds to an MS. Tnεse 160 bearεr bits arε protεctεd by a 16 bit FCW. Sεε Figurε 2-6. At thε subscribers option ARQ εrror correction may be applied to the bearer data. A window size of two is used for the ARQ process. The numbεr of retry attempts are sεtablε by thε sεrvice provider or subscriber. Trie systεm providεs for ratεs grεatεr than thε 8 Kbps basic ratε. Thεsε highεr ratεs, called "Super Rates", are achieved by allocating multiple slots to a single MS. Up to the full bandwidth of the BS, 32 full duplex slots or 256 Kbps (full duplex) in 8 Kbps steps, may be assigned to a single MS. Sεε Figure 2-7. Thε systεm also providεs for data ratεs lower than the 8 Kbps basic rate. This is accomplished by skipping polling cycles. See Figure 2-8. Thus 4 Kbps, 2 Kbps, etc. can be provided. Up to 24 polling cycles may be skipped, at 320 bps per loop, providing a minimum data rate of 320 bps efficiently (i.e., without using rate adaptation). Intermεdiate rates or even lower rates may be obtained by using rate adaptation. Asymmetric data channεls arε supportεd by the system. In this mode the greater portion of a slot can be devoted to eithεr the BS to MS transmission or thε MS to BS transmission. High speεd transport can bε providεd in this mode; up to 12 Kbps sεnt half duplex in either direction, with acknowledgment and ARQ. A spεcific sub-modε, "broadcast", exists in thε asymmetric bandwidth case. Each broadcast sub channεl is idεntifiεd by 3 special broadcast identifier. Up to 255 broadcast channεls may bε idεntifiεd. For thεsε poiπt-to-mulripoint applications, broadcast framεs arε not acknowledged. In addition to the above data channels, therε always exists an out-of-band D channel in each time slot. User data may be sεnt ovεr this channεl without disturbing thε normal bεarεr channεls. Thε data ratε of this channεl is 400 bps. Tnis channεl can bε usεd for any purposε including short mεssaging implεmεntation. 2.8.2.2 Mεssagε Acknowledgment The end usεr has thε option of εithεr activating ARQ εrror corrεction or leaving error correction disabled, for examplε, for vidεo applications. Thε ARQ mεchanism usεs a data window of two framεs. Whεn a framε is dεtεrminεd to bε corruptεd, via the standard ISDN 16 bit FCW, thε rεcεiving unit signals the transmittεr for a rεtransmission. Thε numbεr of re-transmission attempts can be sεt by thε PCS sεrvicε opεrator or the subscriber. Tne maximum uncorrectεd framε εrror ratε of thε systεm is \ 0'~ at thrεshold rεcεivεr sεnsitivity. Aftεr applying ARQ correction the frame error rate is: 10"2 1(216- 1) which is 1.5 X 10" uπdetεctεd frame error rate. For examplε, thε latency of 8 Kbps data corrected by an n=2 ARQ is 80 ms, and the latency of 120 Kbps data corrected by an n=2 ARQ is, on the average, 5.4 ms. In the uncorrected mode the user data block error rate is 10 ~ 2 at u rεshold receiver sensitivity. Data rate and integrity are maintained beforε and aftεr handovεr. Since data may bε lost during thε handover, thε systεm providεs for thε use of higher level protocols to correct the loss of frames. A typical handover delay, including switch time, for an intra Base Station Controller handover is less than 10 ms. The maximum handover time, assuming at communication with the Terminal/nεw BS is error free, is approximately 40 ms. 2.9 Mobile Handoff 2.9.1 Handoff Procedurεs Handoff is rεquired whenever the received signal level at a MS falls below an acceptablε level. Thε PCS2000 Systεm utilizes a Mobile Station-controlled hand off method, which operatεs as dεscribεd in thε following paragraphs. While thε MS is rεcεiving bεarεr traffic from its originating BS, it mεasurεs thε rεcεivεd signal quality of its link. This valuε, togεthεr with the current frame erro rate, determines the link quality. If the quality drops below a first threshold ( the measurεmεnt thrεshold), thε Mobilε sεarchεs during thε TDMA timε slots it is not using, for othεr RF frεquεnciεs/PN codε sεts through all time slots of the originating BS and the Base Stations of adjacεnt cells (This information is downloaded from the originating BS). As the MS finds each new frequency/codεsεt, it mεasures the received signal quality. The MS reads a field carried in all BS frames which describes the currεnt time slot utilization of the BS. The MS uses thεse two piεcεs of information io form a figurε of mεrit for thε πεw BS signals, including thε originating BS, and then sorts thε BSs by figurε of mεrit. Notε that this procεdurε allows thε MS to mεasurε thε quality of othεr timε slots i thε originating BS. If thεsε timε slots havε better quality than those of any BSs in adjacent cεlls, a Timε Slot Intεrchangc (TSI) hand-off is considered, which maintains the link to thε originating Base Station. When the link quality drops below a 2nd threshold level, the MS (during a no- bεarεr timε slot) rεquεsts a hand-off from thε BS with the highεst figurε of mεrit (which could bε a TSI with thε originating BS). Tnε hand-off is rεquεstεd by sεizing a timε slot, sεndiπg a hand-off mεssagε rεquest, and waiting for an acknowledgment from the new Base Station. Tne hand-off signaling message contains a description of the circuit connecting thε originating BS to the PSTN. This information was passed to the MS at call establishment time. If the new BS accepts the hand-off request (by acknowledging), then the new BS becomes the Terminal BS. Notε that the MS maintains thε bearer channel connection with the originating BS during this hand-off procεdurε. 2.9.1.1 Intra-Clustεr Handoff Next, the Terminal BS sεnds a NOTE (message) to its Base Station Controller (BSC), requεsting that the original circuit be switched from the originating BS to the Terminal BS. If the BSC is common to both the originating and Terminal BSs, the hand-off is termed an intra-cluster event, and the BSC bridges the circuit from the originating BS to thε Tεrminal BS. Thε BSC thεn sεnds a circuit-switch- complεtε NOTE to thε originating BS, and also to the Terminating BS, commanding it to continue the hand-off process. If the BSC is not common to both Base Stations, the hand-off procεss continues with an inter-cluster hand-off procedurε. 2.9.1.2 Inter-Cluster Handoff For inter-cluster hand-offs, the BSC translates thε hand-off NOTE into thε signaling languagε of thε PCSC host and rεquεsts an intεr-clustεr hand-off at thε PCSC nεrwork lεvεl. In somε nεtwork architccturεs, thε host PCSC cannot accεpt a hand-off rεquεst from a tεrminating BSC; in which casε an intermediate step is taken. The hand-off request is sent to the PCSC via an X.25 link to the BSC connected to the originating BS. Tne originating BSC then translates the requεst and rεlays it to the PCSC. Thε PCSC acknowledges the circuit switch to the BSC, and the BSC sends a circuit-switch-complete NOTE to the Terminal BS. When thε Tεrmina! BS rεceivεs thε circuit-switch-complete NOTE, it begins paging the MS with a specific poll, and thε originating BS signals thε MS to transfer to the Terminal BS. When the MS rεccivεs thε signal to transfεr to thε Tεrmiπal MS, or if thε link is lost during thε hand-off process, the MS switches to the Terminal BS and searches for a Spεcific Poll. Whεn it receives the Spεcific Poll, thε MS completes the connection to the Terminal BS, and the hand-off is procedure is completed. Should the link between the MS an originating or Terminating BS bε complεtely broken at any time, the MS will search for thε highεst quality BS on its list of potεntial hand-offs, and attεmpt a hand-off without communication with its previous BS. This allows the MS to recovεr from situations in which the original link was broken beforε thε normal hand-off procedure could be completed. 2.9.2.3 Handoff Time Delays For intra-cluster hand-offs the total timε delay for die hand-off procedure, including re-establishment of bearer channel traffic, is typically lεss than 10 milliseconds. The maximum time is approximately 40 ms. Since under normal circumstances the delay is less than one polling loop interval, bearεr packets will continue to the MS with no interruption. Inter-cluster hand-off or Time Slot Interchangε is partially dεpεπdεnt upon thε dεlays inherent in the host PCSC, and are beyond the scope of this genεral systεm description. Over-the-air delays for the intεr-clustεr hand-off arε thε same as above; i.e. 10-40 ms. Break-before-make hand-offs typically take less than 250 ms. Future Enhancements The Omnipoint system allows a PCS operator to add a number of applications beyond voice to the system without protocol modifications. Among these are: 1. Asymmetric links between the base and handset allowing for small bandwidth from the handset to the base and vice versa and a higher bandwidth in the opposite direction. This will provide for some data services that consist of a request by the handset and a large volume of information flowing back to the handset in response . The Omnipoint CAI provides the ability for this enhancement and it will not affect other users or earlier handset interoperability with base stations providing these types of services . 2. Codecs with sampling rates lower than 8 kbps will be supported through the methodology outline earlier. At the present time, Omnipoint believes that 8 kbps is the best choice for an early PCS service introduction and is confident in the codecs chosen for service introduction. 3. Other enhancements as defined and implemented by Omnipoint or licensees of Omnipoint technology. 3. PCS2000 System Performance Requirements 3.1 PCS Cell Coveragε Rεquirεmεnts 3.1.1 Low Basε Station Antεnna Hεights Figurε 3-1 shows εxpεcted cell radii for a bit error rate (BER) of 10E-3, for both 90% and 99% probability of covεragε based on the COST model of mεdian propagation loss, assuming a Basε Station hεight of 10 mεtεrs, building roof hεights of 9 mεtεrs, and a MS antεnna hεight of 1.5 mεtεrs. Large scalε shadowing effects are assumεd to bε Log Normal with a standard dεviation of 8 dB. MS EIRP is 300 milliwatts, BS receiver sensitivity is - 100 dBm, and thε BS antεnna has an omnidirεctional partεrn with a vertical gain of approximately 7 dB. Hata-Okurmura models are not as accurate at the assumed BS antεnna height of 10 metεrs, sincε thεy wεrε originally developed for antenna heights of 30-200 meters. Comparing COST 23 1 predictions with Hata, COST 23 1 range predictions fall betwεen Hata largε city urban and largε city suburban casεs. Omnipoint's Air Intεrfacε architεcturc providεs for εxtrεmεly rapid hand-off between Base Stations, allowing for lεss ovεrlap bεtween cells. Tnis fact is reflected in Figure 3- 1 wherε 75% contours Iεad to 90% ovεrall coverage, and 90% contours lead to 99% overall coveragε. Thεre is significant evidence that at lower BS antenna heights, neither higher receiver sensitivity nor high gain antennas contribute significantly to increasing cell size, because of physical obstructions and rapid increasε of propagation loss versus distancε. At shortεr rangεs, signal strεngth falls off with a IfRA- charactεristic, whilε at longer ranges, signal strength falls off much more rapidly- as high as IfiO or \ft for the lower BS antenna heights. For longer ranges, using higher gain antennas or lower recεivεr sεnsitivity, will do little to increase cell size. To provide greater coverage in such cell propagation environments, Base Stations must be placed closer togethεr. This does not mean that directional antennas have no benefit in smaller cells; their directive is useful for purposes other than increasing cell size; e.g., for dividing a cell into sectors to accommodate higher user dεnsitiεs within certain urban regions. 3.1.2 High BS .Antenna Hεights Figure 3-2 shows expected performance (using the COST 23 1 propagation model) for a BS antenna hεight of 50 mεtεrs. All othεr conditions arε thε samε as in Figure 3- 1. Note that oncε thε BS antεnna is εlεvatεd to this hεight, thε rangε of covεragε incrεasεs significantly. 3.1.3 Maximum Outdoor Basε Station Spacing Maximum BS spacing dεpεnds on thε configuration of Basε Station antεnna usεd and thε dεployment arεa propagation charactεristics. Tablε 3- 1 shows maximum pεrrnissiblε path loss for configurations using 300 milliwatt MS pεak transmit powεr and - 100 dBm BS rεcεivεr sεnsitivity. Maximum cell radii predictions are based on a COST 231 propagation model, with Log Normal shadowing and 8 dB standard deviation.. Table 3- 1 Cεll Radii for 90%/99% Urban Covεragε Probability Table 3-2 shows maximum permissible path loss for configurations using thε sam assumptions as in Table 3- 1 , except MS peak EIRP is 1 Watt. Table 3-2 Cεll Radii for 90%/99% Urban Coveragε Probability Thε information prεsεntεd in Tablεs 3- 1 and 3-2 can bε usεd to calculatε nominal cεll sizεs for suburban εnvironmεnts. Expεctcd maximum cεll radii calculated for the above tables assume that multipath Rayleigh fading and ISI effects have beεn partially mitigatεd by usε of antenna spatial diversity (L =4) at the Base Station, and the usε of DSSS modulation and correlation and detεction. Tnε BS antεnna spatial diversity, which utilizes the channεl sounding capability of the PCP, provides spatial diversity gain for both the forward and reverse links. Cell radii can be further increased by using higher gain antennas at the Base Station. For examplε, if a 26 dBi BS antεnna is usεd, cεll radius could incrεase by 3 to 10 times, assuming propagation losses of 1/R2 or 1/RΛ respectivεly. To providε efficient servicε in low dεnsity rural arεas, cell radii can be extended beyond 8 miles, by providing the increa≤εd guard timεs rεquirεd for thε longer round trip propagation delays encountered in the larger cεlls. Cells with 10 mile radii can be supported by reducing thε number of time slots pεr frame from 32 to 25. Since such large cell radii will only be deployed in low population density areas, reduced cell capacity caused by the smaller number of time slots per frame is not an issue 3.2 Maximum Number of Simultaneous Users per Cell. In urban areas, when population density permits use of Omnidirectional BS antennas, the maximum number of simultaneous users per cell is limited by the number of user time slots per frame in the Omnipoint TDMA design approach, which is 32. Howevεr, for a 1 % probability of call blocking, 32 usεrs per RF channεl can accommodatε (0.68 x 32) Erlangs of traffic or 21.8 Erlangs pεr cell, li it is assumed that subscribers in typical urban arεas usε 0.03 Eriangs,jτιιi___ avεrage, thε Omnipoint cεll could accommodatε 725 subscribεrs. For high dεπsity population applications, thε maximum numbεr of simultanεous usεrs pεr cεll can bε incrεasεd by sεctorizing the cell; e.g., into 3 or 6 sectors. This is accomplished by using directional BS antennas to illuminate 120 degrεε or 60 dεgrεε sεctors of thε cεll. Cεll sεctoring , for thεsε two cases, can increase the numbεr of simultanεous usεrs pεr cεll to 96 or 192, and incrcasε the numbεr of 0.03 Erlangs/user mobilε subscribers to 2175 and 4350, rεspεctivεly. 4. Base Station Performance Requirements 4.1 Transmittεr 4. 1.1 Frεquεncy Agility Tnε Base Station RF system can operate at any frequεncy between 1850 and 1990 MHz in 625 kHz steps. Tnat is, the frequency synthesizers can be programmed to receive and transmit on any one of 223 frequεncies. This step size is not required in the licεnsεd PCS spεctrum for Omnipoint and the system steps in 5 MHz incremεnts. Thεrεforε, thε first channεl is normally ccntεrεd at 1852.5 MHz, the nε.xt at 1857.5 MHz, εtc. PCS2000 doεs not normally opεrate in the 1910 to 1920 MHz band becausε frequency band is reserved for asynchronous unlicensed devices. The system can operatε in thε isochronous band between 1920 and 1930 MHz. The first channel in this band is centered at 1920.625 MHz, and the channel spacing is 1.25 MHz across this band. 4.1.2 Frequency Stability The transmitter frequεncy stability is controllεd by thε systεm mastεr clock in thε Ba≤ε Station. Thε frεquεncy rεfεrεnce is a crystal stabilized 10 MHz precision rεfεrεncε oscillator. This reference is stable to within 1 part in 0.01 ppm over all operating conditions. This referencε can also bε synchronizεd to the external digital network for precisε timing with thε telεphonε nεtwork 4.1.3 Synchronization with Thε Base Station Controllεr Nεrwork Thε main frεquεncy reference for the Basε Station can bε frεquεncy lockεd to thε Basε Station Controllεr Nεtwork. This synchronization is pεrformεd automaticall by digital circuitry that dεrivεs a DC control voltage for the rεfεrεncε oscillator. This control voltagε is fεd to thε DC frεquεπcy trim adjust to fine tune the refεrεncε oscillator. Normally, thε digital phonε nεtwork usεs a vεry prεcisc frεquεncy standard to synchronizε thε entire network. This frequεncy accuracy is passed on to the RF Base Station in this fashion. The control range of the εlεctronic frequεncy trim adjust is limited to lεss than +/- 10 ppm to ensurε that th RF stability cannot εxcεεd thε FCC limits undεr any faulty nεtwork condition. 4.1.4 Power Output (EIRP) 4.1.4.1 TDMA Power Pulse Waveshape A constant envelopε wavεform is gεnεratεd by basεband pulsε shaping thε I and Q data inputs to a quadraturε modulator. Thε particular pulsε shapε of thεsε waveforms detεrminεs thε spεctral occupancy of thε transmittεr, as well as the intersymbol intεrfεrεncc of thε wavεform. Thε transmittεr can be operated in a fully saturated power output mode which allows the maximum power output available from the transmitter to be utilized for increased link margin. Unlike other modulated waveforms that have significant amplitude modulation, constant envelopε waveforms may bε compressed (limited in the amplitude sense), without the spectral rε growth associated with thesε other waveforms. This allows the use of amplifiers that are relatively less expensive. They do not require OBO (output back off), or extrεmε linεarization tεchniquεs (such as fεεd forward or Cartεsian fεεdback to thε modulator) to obtain good spectral purity. Further, since they can be operatεd at saturation, thε power consumption is also relatively less. Typical OBO values for non-constant εnvelopε signals are in thε 4 to 7 dB range. This reduction may affect the link budget of the systεm. 4. 1.4.2 Averagε Power Output The Averagε Power Output of thε Base Station Transmitter is approximately 50% of the Peak Powεr Output. Peak Powεr Output is 2 Warts in thε licεnsεd frεquεncy bands, and thε duty cyclε is approximately 50%. Therefore the maximum Averagε Powεr Output is approximately 1 Watt. With the Power Control adjusted to the minimum power output on εach timε slot of thε Basε Station Transmittεr (powεr control is pεrformεd on a slot by slot basis). The averagε is thεn (2 W - 33dB)x(50%)=0.5mW. Thε actual Avεragε Powεr Output will normally bε bεrwεεn thεsε two εxtrεmεs, dεpεnding on thε individual power settings of all 32 time slots. For the unlicensεd PCS band, thε power output is limited to 1 12 m W for 1.25 MHz channels. This has the effect of reducing thε avεragε power output to approximatεly 56 W for thε unlicεπsεd sεrvicε. 4.1.5 Spurious RF Emissions 4.1.5.1 Conductεd Conducted emission complies with FCC Part 24.238 -Emission Limits for the licensεd PCS bands, and FCC Part 15 Subpart D -Unlicensed Personal Communications Sεrvicεs Devices for thε unlicεnsεd sεrviccs. 4.1.5.2 Radiated Radiatεd εmission complies with FCC Part 15 rules for incidental and intentional radiators. The radiatεd εmissions also comply with ANSI C95.1 - 1991. 4.1.5.3 Total Spurious Emission All spurious out-of-band emission, including but not limited to Lhat due to modulation spectral sidelobes, transmitter harmonics, transmitter switching, power control transients, or multiple co-sited transmitter intermodulation, will be εqual to or lεss than: (-43 + 10 1og P) dB where P is the in-band powεr of thε modulated signal 4.2 Rεcεiver 4.2. 1 Frεquεncy Agility A common synthεsizεd local oscillator is usεd for both transmit and rεcεivε. Sεε sεction 4.1.1 for dεtails. 4.2.2 Frεquεncy Stability/Synchronization Thε samε mastεr clock that is used for transmit is usεd for rεcεivε. Sεε sεction 4.1.2 for dεtails. 4.2.3 Sensitivity Thε rεcεive sensitivity is - 102 dBm for 10°. 4.2.4 Spurious RF Emission RF emission from thε Basε Station rεcεivεr εεt thε FCC Part 15 iπcidεntal radiator rulεs. 4.3 Antεππa Pεrformancε Spεcifications Base Stations may be configured with either omnidirectional or high gain directional antεnnas (or a combination) depεnding on the specific RF coverage nεεds for εach basε sitε. In addition, to pεrmit a single Base Station to cover a large sparsely populated area, a steerablε phased array antenna may be used. (Ref. 2.3.2.3) 4.3.1 Omnidirectional Antennas 4.3.1.1 Gain: Omnidirectional antennas vvill have a nominal gain of 5 to 10 dBi. 4.3.1.2 Vertical Beamwidth: Omnidirεctional antεnnas will havε a nominal vεrtical bεamwidth of 8 to 35 degrεεs. 4.3.1.3 Polarization: Omnidirεctional antennas will be vertically polarizεd. 4.3.2 Dirεctioπal .Antεnnas 4.3.2.1 Gain: Dirεctional antεnnas will havε a nominal gain of 10 to 17 dBi. 4.3.2.2 Vεrtical Beamwidth: Dirεctional antεnnas will have a nominal vertical beamwidth of 7 to 35 degreεs 4.3.2.3 .Azimuthal Bεamwidth: Dirεctional antεnnas will havε a nominal azimuthal beamwidth of 15 to 120 degrεεs. A minimum front-to-back ratio of 20 dB is rεquirεd. 4.3.2.4 Polarization: Directional antεnnas may be εithεr vertically or circularly polarized. 4.3.3 Phased .Array Antennas 4.3.3.1 Gain: Phasεd array antennas will have a nominal gain of 26 to 28 dBi. 4.3.3.2 Vertical Beamwidth: Phased array antennas will have a nominal vertical beamwidth of 8 degrees. 4.3.3.3 .Azimuthal Beamwidth: Phased array antennas will have a nominal azimuthal beamwiddi of 8 degreεs. A minimum front-to-back ratio of 20 dB is required. 4.3.3.4 Polarization: Phasεd array antennas will be circularly polarized. 4.3.4 Diversity for Mitigation of Multipath Effects 4.3.4.1 Spatial Diversity The Basε Station will use spatial antεnna diversity with L = 2, 3, or 4 depεnding on thε sevεrity of thε multipath conditions of each base sitε. Tnε physical sεparation of thε antεnnas will bε at least 10 wavelengths. 4.3.4.2 Antenna Selεction Algorithm Several metrics arε employed to determine thε signal quality at εach antεnna. Tnε rεsults of thεsε mεasurεments are used to select the best antenna for transmission/reception for εach TDMA timε slot. 5. Mobile Station Performance Requirements 5.1 Transmittεr 5. 1.1 Frequency Agility The Mobilε Station can bε sεt to opεratε on any frequency between 1850 and 1990 MHz in 625 kHz steps. Tnat is, the frequency synthesizers can be programmed to receivε and transmit on any one of 223 frequencies. Omnipoint does not require this step in the licensεd PCS spectrum and the system steps in 5 MHz increments. Therεforε, thε first channel is normally centered at 1852.5 MHz, the next at 1857.5 MHz, etc. The systεm doεs not normally opεratε in the 1910 to 1920 MHz band. This frequency band is rεsεrvεd for asynchronous unlicensεd devices. The system can operate in the isochronous band bεtwεen 1920 and 1930 MHz. The first channel in this band is centered at 1920.625 MHz, and the channel spacing is 1.25 MHz across this band. 5.1.2 Frequεncy Stability The initial Mobilε Station clock stability is accuratε to within +/- 10 ppm from -30 C to +60 C. 5.1.3 Synchronization with Base Station The Mobilε Station clock is automatically fine tuned to the Base Station oncε thε mobilε rεcεivεr rεcεivεs thε Basε Station signal. This providεs adεquεatε frequency stability and network wide synchronization to thε Mobilε Station. 5.1.4 Powεr Output (EIRP) Thε mobiiε station transmittεr has a maximum powεr output of 600 mW into an εlεvatεd fεεd dipolε. Thε rεsulting EIRP is 1 Watt. 5.1.4.1 TDMA Powεr Wavεform vs. Time Thε transmittεr has a controllεd on-off switching charactεristic to εliminatε unwantεd spεctra! sprεading transiεnts. 5.1.4.2 Handsεt Avεragε Power Output The Peak Handset Output Power is 600 mW. The Handset Average Power Output is dεtεrmined by the number of time slots aggrεgatεd to dεlivεr die dεsirεd data ratε. Each timε slot dεlivεrs an 8 kbps data rate, so a 32 kbps usεr nεεds 4 timε slots and thεrεforε has 4 timεs thε average power output of an 8 kbps user. The duty cycle of a single slot (an 8 kbps user) is approximately 1/64 and the resulting average power output is approximately 9.4 mW. Thεrεforε, the average power output of a 32 kbps user is 37.6 mW. Powεr control can furthεr rεducc the avεragε power output as directed by the Base Station. 5.1.4.3 Transmit Power Control by Basε Station Transmit Power Control is directed by the Base Station in 3 dB steps over a total range of 33 άB ' . This is performed by a four bit control of 3 dB, 6 dB, and two 12 dB switched RF attenuators. PCP, the Power Control Pulse is transmitted by the MS just beforε the time that the BS is expected to transmit to the MS. The PCP thus provides a power measuremεnt of the mobile channel to thε BS and is the basis for thε powεr control command to be sεnt to thε MS. A multi-receiver BS can also make an antenna selection for transmit based on the quality of the PCP signal arriving at the BS. In TDMA systεms thε latεncy of thε signals around thε polling loop gεnεrally inhibit thε usε of power control. That is, the length of time around the polling loop is too long to allow the last transmission to be very useful to estimate the channel losses and impairments. In most fixed station applications, the antenna locations , patterns, and powεr transmitted by the fixed station may bε adjustεd for minimal interference to other fixed stations. However the nature of cellular-like mobile stations is such that thεy can conflict with othεr mobilε stations at intεrsεcting cεll boundariεs. This crεatεs thε nεεd for somε power control in thε mobilε stations. For εxamplε, a handsεt opεrating at thε boundary of its BS covεragε nεεds to transmit its full powεr to stay in contact. However, a handset opεrating in thε samε timε slot, rεlativεly closε to its own BS, doεs not nεεd to transmit full powεr to havε good contact. Tne BS can measurε the channel with the PCP and tell the MS to adjust its power if neεdεd. Tnε BS can also usε thε PCP to mεasurε thε time delay from a MS and estimate its distance from the BS. Further, if thε BS knows thε powεr sεtting of the MS, it can also adjust its own power as well. 5.1.5 Spurious RF Emission 5.1.5.1 Conducted Conducted emission complies with FCC Part 24.238 -Emission Limits for thε licεnsεd PCS bands, and FCC Part 15 Subpart D -Unlicensed Personal Communications Servicεs Dεvicεs for thε unlicεnsεd sεrviccs. 5.1.5.2 Radiatεd Radiatεd εmission complies with FCC Part 15 rules for incidental and intentional radiators. The radiatεd εmissions also comply with ANSI C95.1 - 1991. 5.1.5.3 Total Spurious Emission All spurious out-of-band εmission, including but not limited to that due to modulation spectral sidelobes, transmitter harmonics, transmitter switching, power control transients, or multiple co-sitεd transmitter intermodulation, will be equal to or less than: (-43 ÷ 10 1og P) dB whεrε P is thε in-band power of the modulated signal 5.2 Recεivεr 5.2.1 Frεquεncy Agility A common synthεsizεd local oscillator is usεd for both transmit and rεcεivε. Sεe sεction 5.1.1. 5.2.2 Frεquεncy Stability/Synchronization Thε samε mastεr clock that is usεd for transmit is used for recεive. See section 5.1.2 Frequεncy Stability 5.2.3 Sεnsitivity The rεcεivε sεnsitivity is - 100 dBm for 10 " BER 5.2.4 Spurious RF Emission RF emission from the Mobile Station Receiver meets thε FCC Part 15 Incidεntai Radiator rulεs. 5.3 .Antεnna Pεrformancε Spεcifications 5.3.1 Mobilε Handsεt Antεnna 5.3.1.1 Gain: The mobile handsεt aπtεnna will havε a nominal gain of 2 dBi. 5.3.1.2. Beamwidth: The mobile handset antenna will have a nominal vertical beamwidth of 70 dεgrεεs, perpindicular to thε antεnna axis. 5.3.1.3 Azimuthal Bεamwidth: The mobilε handsεt antεnna is omnidirectional. 5.3.1.4 Polarization: Thε mobilε handsεt antenna is polarized along thε major axis of th handset , MS. 5.3.2 Mobile Vεhicular Antεnna 5.3.2. 1 Gain: Thε mobilε vehicular antenna will have a nominal gain of 5 dBi. 5.3.2.2 Vertical Beamwidth: The mobilε vεhicular antεnna will have a nominal vertical beamwidth of 35 degrees. 5.3.2.3 Azimuthal Beamwidth: Thε mobile vehicular antenna is omnidirectional. 5.3.2.4 Polarization: Thε mobilε vehicular antεnna is vertically polarized. PCS2000 Sec 6.1 Layer 1 RF Characteristics 6. 1 RF Characteristics This section describes the RF characteristics of the basic Omnipoint PCS system. For certain applications, values of some system RF parameters wiU change. 6 . 1 . 1 Transmit This section describes the RF characteristics of the transmitters for both the Base Station (BS) and the Mobile Station (MS). . 1 . 1 . 1 Modulation Method Omnipoint uses a form of continuous phase modulation (CPM) which provides the desirable characteristics of a constant RF envelope and minimal sidelobes. The constant envelope characteristic of CPM permits. efficient nonlinear RF power amplification in the transmitter. pow amplifier of the MS handset (as well as the BS), without regrowth of the spectral sidelobes associated with most forms of digital phase modulation. 6. 1 . 1 . 2 Transmit Spectrum/Pulse Shaping After CPM RF modulation, the RF signal is bandpass filtered to further reduce the out of band spurious emissions. The in-band amplitude and phase versus frequency characteristics of the RF bandpass filters must be carefully controlled. Otherwise the filters can distort the CPM signal, causing it to lose its constant envelope characteristic, thus causing sidelobe regrowth after nonlinear power amplification. The attack and decay times of the transmitted RF signal are controlled during the turn ON and turn OFF transient periods to prevent splatter into adjacent R bands. 6. 1 . 1 . 3 Transmit Power Levels Although the FCC permits up to 2 Watts EERP for the MS, the nominal peak power output for the Omnipoint MS is 600 milliWatts into a dipole antenna, or 1 Watt EERP. With Omnipoint's Version 2T.X TDD/TDMA design approach, the average MS power output in the 8 Kbps mode is only 9.36 milliWatts, permitting longer durations between battery recharges. With this low value of MS transmit power, large PCS cell sizes can be accommodated because high gain directional antennas can be economically incorporated in Omnipoint's Base Station design. Not that with Omnipoint's TDMA radio system designs, only a single steering mechanism is required to address all users in one cell or cell sector, thus significantly reducing system complexity and cost. Contrast this capability with other systems which require as many steering mechanisms as there are potential users within each cell. The FCC PCS Report and Order allowed up to 100 Watts peak EERP for PCS Base Stations for each RF channel utilizεd by thε BS. Thεreforε, maximum pεrrnissiblε avεragε EIRP pεr channe in Version 2T.X is 50 Watts. The nominal peak power output of a standard Omnipoint base station is 2 Watts. However, for larger cell applications and for certain propagation environments, the BS utilizes a directional antenna with a nominal antenna gain of 17 dBi. This provides a peak EIRP of 100 Watts, meeting the FCC requirement. By utilizing a steεrable directional antenna, each user link within the cell takes advantage of the gain of the directional antenna at the BS, for the reverse link as well as thε forward link in Version 2T.X. Many petitioners in the Reconsideration process requested that ihe FCC raise the power limit to 1000W which allows Omnipoint's system to use up to 26 dBi gain antennas. Because Omnipoint's system design utilizes a direct sequence spread spectrum form of modulation for all MS and BS transmissions, the RF power density is much lower than for narrowband PCS systems, causing less interference with OFS users sharing the same RF speαrum. 6. 1 . 2 Receive This section describes the general characteristics of Omnipoint's Mobile Station and Base Station RF receiver functions. 6. 1 . 2. 1 Receiver Selectivity With a nominal 5 Mcps spread spectrum pn code overlay, the required receiver front end (RF) bandwidth is 5 MHz for Version 2T.X. This bandwidth is maintained through down conversion to an intermediate frequency (IF) until despreading occurs and processing of the information content of the received signal begins, at which time the receiving channel bandwidth is reduced to that required for the digital information signal. By providing the minimum RF, EF, and baseband signal bandwidths required, the receiver is optimized for front end thermal noise, as well as potential adjacent channel interferers. Receiver bandwidths must be wide enough to accommodate expected variations caused by transmitter and receiver local oscillator variations over time and temperature, as well as Doppler shifts. The same selectivity considerations apply t both the MS and the BS receiver designs. 6. 2. 2. 2 Receiver E)ynaπ_c Range Because of variable RF path lengths within the PCS cell and because of fading channel propagation and shadowing effects, received signal levels at both the MS and BS sites can vary over a very wide dynamic range. To prevent the stronger of received signals from overloading the front end, RF front ends arc designed to handle a large dynamic range. Selection of RF amplifiers with low noise figures and good linearity at maximum expected signal levels minimize signal distortion effects which can reduce spread spectrum processing gain, and cause intermodulation distortion. 177 6. 1 . 2. 3 Signal Quality Measurement of the Physical Interface To reduce the requirεd iπtεrfereπce dynamic range rejection of the BS receivers, Omnipoint utilizes an adaptive power control algorithm. Implementation of this power control feature requires measuremεnt of the quality of the signals received from each MS. In Version 2T.X this is done by having the BS measure the received RF power as well as the signal to noise/interference ratio during a proprietary Power Control Pulse (PCP) transmitted by each MS during its assigned TDMA time slot. With Omnipoint's design, the MS transmits a PCP, the BS makes a measurement of received signal quality and transmits a command to the MS to increase or decrease its transmitted power level and the MS responds, all within 500 us— a fraction of a time slot duration. Since the BS transmits sequentially to all MSs within its cell in adjacent TDMA time slots, each BS-to-MS link may vary in path loss. Control of BS transmitter power is possible on a slot by slot basis. Each MS measures received BS signal quality from its own cel and uses this information to determine when to measure signal quality from adjacent cells and, further, when to request handover to an adjacent cell when the received signal quality from its present BS falls below a preset threshold level. 6. 1 .3 General Characteristics This section discusses certain characteristics of the PCS RF channel which arc common to both the Base Station and Mobile handsets. 6. 1 . 3. 1 Air Interface Data and Symbol Rate Omnipoint's TDMA design approach permits up to 512 Kbps of bearer channel information simplex or 256 Kbps of bearer channel information in non-VAD full duplex mode. The instantaneous burst data rate is higher to accommodate overheads and guard time (see Packet an Frame Structure). The symbol rate is significantly lower than the data rate and is proprietary to Omnipoint. . 1 . 3. 2 RF Stability Requirements. For the Base Stations and the MS, Omnipoint provides a guaranteed transmitter carrier frequenc stability equal to or less than +\- lOppm over the operating temperature range. Base station operating frequency may be synchronized to external sources for the more precise timing potentially required for interface to digital networks, external clocks and frequency standards. Mobile units may also acquire synchronization from the Base Station for similar precise frequenc control. 6. 1.3.3 Intermodulation Intermodulation distortion must be considered for co-located Base Stations operating on multiple RF channels. Omnipoint has designed the transmitter RF power output stage and antenna coupling to minimize this effect. 178 6. 1 .3.4 Channelization Nominal RF channel spacing for the Omnipoint Version 2T.X CDMA/TDMA FDMA system, utilizing a 5 Mcps spread spectrum modulation, is 5 MHz. For applications that do not require a large a spread bandwidth, lower chip rates with closer channel spaciπgs can be provided. 6. 1 .3.5 Spurious RF Emissions Al spurious out-of-band emissions including but not limited to those due to modulation spectral sidelobes, transmitter harmonics, transmitted switching, power control transients, or multiple co- sited transmitter intermodulation shall be equal to or less than (- 43 dB + 10 log P) dB. 6. 1 . 3.6 Multiple Access Method Omnipoint uses a unique combination of CDMA TDMA, and FDMA for multiple user access to the PCS network. Within a cell, time division multiple access (TDMA) is employed and time division duplexing (TDD) or frequency division duplexing (FDD) can be used, allowing up to 64 simultaneous 8 Kbps bearer channels in simplex mode or 32 simultaneous, 8 Kbps full duplex mobile users, while adjacent cells are set to different frequency channels (FDMA) under a minim N = 3 architecture. Cells beyond immediately adjacent cells use a variety of separation techniques, including code (CDMA), power control, directional antennas and time slot interchange (TSI) for additional inter-cell isolation. By utilizing a TDMA approach within a cell and not relying solely on CDMA for separating multiple MS signals at the Base Station, self interference at the BS receiver is greatly reduced, permitting greater area coverage for a given M transmitter power output level. Further, as a cell becomes loaded near capacity, cell sizes remain constant and do not shrink as may be the case with other CDMA-oπJy architectures. In the Omnipoint System CDMA is used to maintain low symbol rates while providing very high data rates and to achieve better C VI ratios and frequency reuse. Without the use of these spread spectrum techniques, high data rates are difficult to reliably maintain in fully mobile communications channels. 6. 1 . 3. 7 Duplex method Time Division Duplexing (TDD) or Frequency Division Duplexing (FDD) can be utilizεd to provide two-way access to each MS-to-BS PCS communications link. In Version 2T.X, each time slot within the TDMA frame is divided into equal transmit portions for the MS and thε B with appropriatε guard timεs. Wnen the BS is transmits, the designatεd MS rεcεives, and vice vεrsa. 6. 1.3.8 Multiple Access Dependency Omnipoint's Version 2T.X TDMA. structure is based on a 20 millisecond polling loop for MS access to the Base Station. The 20 ms TDMA frame supports 64 8 Kbps simplex time slots or paired 8 Kbps full duplex time slots each of 625μs duration. There are provisions for each M to aggregate multiple time slots to afford a user more bandwidth for higher data rates as require Asymmetric data rates can be supported on a frame by fr me basis, permitting Voice Activity Detection (VAD), high speed data transport, and data broadcasting by the BS. 6. 1 . 3. 9 Power Control Method Although the Omnipoint method of Time Division Multiple Access (TDMA) docs not require t strict control of transmitter RF power output necessary to resolve the "Near-Far" problem experienced by CDMA PCS systems, the Omnipoint system does utilize a proprietary method o controlling transmitted RF power levels. This is done to reduce battery consumption and to minimize interference in nearby or distant cells which may be operating on the same or adjacent RF channels as well as nearby OFS users. 6. 1 . 3. 9. 1 Control of Base Station Power Output Since the Base Station (BS) can communicate with up to 64 Mobile Stations (MS) within its cel each of whose distance from the BS can vary from near zero up to the radius of the cell, it may not be desirable to control the BS transmitter power to maintain near-constant received power level at each MS. This could require very large changes (>40 dB) of BS transmit power durin each time slot (625 μs) of the TDMA frame. Omnipoint provides BS power control and is investigating the various alternatives to utilize BS power control on a slot-by-slot basis as well a cell-to-cell and cell-to-OFS microwave user. 6. 1 .3. 9. 2 Control of Mobile Station Power Output To permit RF channel reuse in nearby PCS cells, to reduce interference with OFS users, and to conserve battery power in the handheld units, Omnipoint provides adaptive power control of th Mobile Station transmissions within each PCS cell. A proprietary Power Control Pulse (PCP) system has been designed. In Version 2T.X, the PCP transmitted by the MS in its assigned TDMA time slot just before the BS transmits to that MS i its associated TDD time slot. This MS PCP provides the BS with a measurement of the MS-BS path transmission loss, which serves as the basis for a Power Control Command (PCC) transmitted from the MS to the Base Station. The PCC causes the MS to change its output power in minimum steps of 3 dB, depεndεπt on thε quality of thε PCP rεcεivεd by thε BS. In somε TDMA systεms, thε latεncy of thε polling loop signals prεvεnt thε use of closed loop power control. However, with Omnipoint's Version 2T.X TDD/TDMA design approach, thε elapsed time for transmission of the PCP, the response by the MS, and the next MS bearer transmission burst, is less than 500 us-less than 2.5% of the frame time. Because of its fast response time, Omnipoint's Power Control algorithm can respond faster than the rate of change o small scale multipath fading effects and propagation shadowing effects. The BS can also use the PCP information to measure the propagation time to each MS within its cell. This provides an estimate of the range from the BS to each MS. For 91 1 support, if the PCS service operator invests in the necessary software, a handset could provide PCP signals to multiple BSs for rough location estimation in emergency situations. Acronyms 1.2.1 Acronyms A/D Analog to Digital AC Authentication Center AC Automatic Callback ACD Automatic Call Distributor ACK Acknowledge(normally the rεcεipt of a packεt of information) ACSE Association Control Sεrvicε Elεmεnt AE Application Entity ALT Automatic Link Transfεr AMA Automatic Mεssage Accounting ANI Automatic Number Identification ANSI American National Standards Institute APDU Application Protocol Data Unit API Application Protocol Interface AR Automatic Recall ARC Automatic Reverse Charging ARQ Automatic Re-send reQuest ASE Application Servicε Element ASP Application Service Part BCD Binary Coded Decimal BER Bit Error Rate BRI Basic Rate Interface CAMA Centralized Automated Message Accounting CAVE ' Cellular Authentication and. Voice Encryption CCAF Call Control Agent Function CCF Connection (Call) Control Function CCITT International Telegraph and Telephone Consultative Committee [now ITU-T] CCIR Consultative Committεe for International Radio [now ITU- . RS] CDMA Code Division Multiple Access CNI Calling Number Identification CPN Calling Party Number CPS Calling Party Sub-address BS Basε Station CCITT International Telegraph and Telephone Consultati Committεε CCS7 Common Channεl Signalling 01 CGSA Cellular Geographical Sεrvicε Arεa CHNO Channεl Numbεr CND Calling Numbεr Display CNDB Calling Numbεr Display Blocking CPSQM Continous Phasε Shift Quadrature Modulation CSS Cellular Subscriber Station CSSINACT CSSInactive INVOKE CSSIT CSS Inactivε Timεr CT Cordless Telεphony CTT Clear Trunk Timer CUG Closed User Group DACW Distinctive Alerting/Call Waiting DCE Data Circuit-Terminating Equipment DID Direct Inward Dial DMAC Digital Mobile Attenuation Code DMH Data Messagε Handlεr DN Dirεctory Numbεr DPC Dεstination Point Codε DSP Digital Signal Procεssor DSSS Dirεct Sequence Spread Spectrum DTE Data Terminating Equipment DTMF Dual Tone Multi Frεquency DVCC Digital Verification Color Code DXE Data Terminating or Data Circuit-Terminating Equipment ECSA Exchange Carrier Standards Association EEPROM Electronically Erasable and Programmable Read Onl Memory EIA Electronic Industriεs Association EIR Equipment Identity Register ESN Electronic Serial Numbεr FACCH Fast Access Control Channel FAX Facsimile 183 FC Feature Code FEATREQ RemotεFεaturεControlRεquεst INVOKE FDD Frεquεncy Division Duplεxing FDM Frεquεncy Division Multiplexing FDMA Frεquεncy Division Multiple Accεss FEC Forward Error Corrεction FIFO First In, First Out FPLMTS Future Public Land Mobile Telεcommunication Systεms FSK Frεquεncy Shift Kεying FU Functional Unit GTT Global Title Translation HLR Homε Location Rεgistεr HLR/AC Homε Location Rcgistεr/Authentication Ccntεr HOT Handoff Ordεr Timεr HTTRT Handoff To Tnird Rεsult Timεr HTTT Handoff To Tnird Timεr IA Incoming Accεss IBS Intelligent Base Station ICB Incoming Call Barred ID Idεntifiεr IEEE International Association of Electrical and Electronic Engineers IF Intermediate Frεquεncy IN Intelligent Network INAP Intelligent Network Application Protocol IS Interim Standard ISDN . Integratεd Sεrviccs Digital Network ISO International Standards Organization ISUP ISDN User Part ITT Information Transfer Interface ITU International Telecommunications Union ITU-R ITU-Radiocommunication Sector (formerly CCIR) ITU-T ITU-Tεlεcommunication Standardization Sector (formerly CCITT) IW Interworking IWF Interworking Functions LAPB Layer Application Protocol "B" 184 LAPD Link Accεss Protocol "D" primarily used in the ISDN " channεl LAPM Link Accεss Protocol Modern (seε V.42) LATA Local Accεss and Transport Area LEC Local Exchange LMMRT Location Measurement Maximum Response Timer LOCREQ LocationRequεst INVOKE LRT Location Rεquεst Timer MA Mobile Application MAHO Mobilε Assistεd Hand-off MAP Mobilε Application Part MAT Mobilε .Arrival Timεr MDHO Mobilε Dirεctεd Hand-off MF Multi-frequency MHOT Mobile Handoff Ordεr Timer MHS Messagε Handling Systεms MTN Mobilε Idεntification Number MNP Microcom Network Protocol MNP 10 Microcom Network Protocol Class 10 MOS Mean Opinion Score MS Mobile Station MSA Mobilε Sεrvice Arεa MSC Mobile Switching Cεnter MSC-G (IS-41.1-B) Mobile Switching Cεntεr - Gateway MSC-H Mobile Switching Centεr - Homε MSC-V Mobilε Switching Ccntεr - Visited MSCG (?) Mobile Switching Center Gateway MTP Message Transfer Part MTSO Mobile Telεphonε Switching Office NAK No acknowledgemεnt (usually of the receipt of a packet o information) NAM Number Assignment Module NANP North American Numbering Plan NOC Network Operations Centεr NPA Numbεring Plan Arεa (Arεa Code) NSAP Network Service Access Point NXX Office Code 185 OA Outgoing Accεss O.AM&P Operations, Administration, Maintenance and Provisioning OCB Outgoing Call Barred OPC Originating Point Code OPDU Operation Protocol Data Unit OSI Open Systεms Intεrconnεction PABX Privatε Automatic Branch Exchange PACA Priority Access and Channel Assignment PAD Packet Assembly Disassembly PBX Private Branch Exchange PC (IS-4 1. I -B) Point Code PC (?) Protocol Conversion PCM Pulsε Codεd Modulation PCS Pεrsonal Communications Services PCSC PCS Switchingl Centεr PDN Public Data Network PDU Protocol Data Unit PI Presεntation Indication PID Pεrsonal Terminal Identifier PIN Personal Identification Number PLCS Personal Communications Location Service PMC Personal Mobility Controller PMD Personal Mobility Data-store PMM Personal Mobility Managemεπt PPDU Presentation Protocol Data Unit PPTN Public Packet Telεphone Network PRl Primary Rate Interfacε PROFDIR ServiceProfileDirective INVOKE PROFREQ ServiceProfileRequest INVOKE PSP PCS Service Provider PSPDN Public Switched Packet Data Network PSTN Public Switched Telεphone Network QAM Quadrature Amplitude Modulation QDT Qualification Directive Timer QOS Quality of Servicε QPSK Quaduaturε Phasε Shift Kεying 186 QRT Qualification Request Timer QUAI.DIR QualificationDirεctive INVOKE QUALREQ QualificationRεquεst INVOKE RA Rate Adaptation RAND Random Numbεr RASC Radio Accεss Systεm Controller RCID Radio Channεl Identifier RCT Registration Cancellation Timεr RDRT Redirεction Requεst Timεr REDREQ RεdirεctionRεquεst INVOKE REGCANC RεgistrationCancεllation INVOKE REGNOT RεgistrationNotiπcation INVOKE RF Radio Frεquεncy RFCT Rεmotε Fεaturε Control Timεr RN Rεdirεcting Numbεr RNI Rεdirεcting Numbεr Identifiεr RNT Registration Notification Timer RO Remote Operation ROUTREQ RoutingRequεst INVOKE RP Radio Port RPC Radio Port Controllεr RPCU Radio Port Control Unit RPI Radio Port Intεrmediary RPT Radio Personal Terminal RRT Routing Rεquest Timer RSSI Rεcεived Signal Strength Indication RSSI ) Recεived Signal Strength Indicator SACCH Slow Access Control Channel SAT Supervisory Audio Tone SBI Shortened Burst Indicator SCA Selective Call Acceptance SCAI Switch-to-Computer Applications Interface SCC SAT Color Code SCCP Signalling Connection Control Part SCEF Servicε Crεation Environmεnt Function SCF Sεlεctivε Call Forwarding 187 SCF Servicε Control Function SCM Station Class Mark SCP Sεrvicε Control Point SCR Selective Call Rejεction SI Screening Indicator SDF Servicε Data Function SDLC Synchronous Data Link Protocol SI Scrεεning Indicator SID Systεm ID SLE Screεning List Editing SLF Scrεεning List Fεaturεs SMAF Servicε Management Access (Agent) Function SMDI Simplified Messagε Desk Iπtεrface SMF Servicε Management Function SPDT Service Profile Directive Timer SPDU Session Protocol Data Unit SPRT Service Profile Requεst Timεr SRF. Spεcializεd Rεsourcε Function SS7 Signalling Systεm Numbεr 7 SSN Subsystεm Numbεr ST Signaling Tonε STP Signal Transfεr Point SWID Switch Idεntification SWNO Switch Number TA Terminal Adapter TBCD Telεphony Binary Coded Dεcimal TC Transaction Capabilities TCAP Transaction Capabilities Application Part TDD Time Division Duplexing TDM Time Division Multiplexing TDMA Time Division Multiple Access TE Terminal Equipment THTTT Tandem Handoff To Third Timer TID Terminal Idεntifier TR Tεchnical Report TLDN Temporary Local Directory Number 188 TLDNAT Temporary Local Dirεctory Number Association Timεr TMC Terminal Mobility Controller TMD Terminal Mobility Data-store TMM Terminal Mobility Managemεnt TMN Telecommunication Managemεnt Network TPDU Transport Protocol Data Unit TRANTJMREQ TransfεrToNumbεrRεquest INVOKE TSAP Transport Service Accεss Point TSC Tεchnical Sub-Commiftεε TSR Timε Slot and Ratε Indicator TTNRT Transfεr To Number Requεst Timεr UCH User Channεl or Voice Channel UDT Unitdata Messagε UDTS Unitdata Sεrvice Message UNRELDIR UnreliablεRoamεrDataDirεctivε INVOKE UPN Usεr Providεd Numbεr UPT Univεrsal Pεrsonal Telecommunication UPTϋ Universal Personal Tεlεcommunication Number URDDT Unreliable Roamer Data Dirεctivε Timer VCH Voice Channεl UTC Coordinatεd Univεrsal Timε VBD Voice Band Data VC Voicε Channεl VLR Visitor Location Rεgister VMAC Voice Mobile Attenuation Code VMS Voice Messagε Systεm WAMS Wireless Access Mobility Services XXXX Station Number (in context of NPA-NXX-XXXX) Definitions 1.2.2 Definitions A-key A secrεt, 64-bit pattεm stored in the mobile station. It is used to gεnεrate/update the mobile station's Sharεd Secret Data. The A-kεy is usεd in thε Tnobilε station authεntication procεss. Abbreviated Alert Thε abbrεviatεd alεrt ordεr is usεd to remind thε user that previously selected alternative routing featurεs arε still activε. Access Denial Call Treatment A tonε, announcement, or call redirection applied as appropriate. ACCOLCp A four-bit number used to identify which overload class field controls accεss attempts. Accounting Management - set of functions which enables the measurement of the use of the network servicε so that the charge for such use can be determined. Acoustic Echo Cancellation - Activation - Advice Of Charging - Information which may be provided to a usεr regarding the cost of a call Alerting Area - a territory in which a wirεlεss terminal is registered for alerting. Note : The alerting area may or may not be identical to the terminal registration area. Alerting Identifier - a unique value across an alerting area assigned to a tεrminal at registration. Analog Access Channel An analog control channel used by a mobile station to access a system to obtain service. Analog Color Code An analog signal (see Supervisory Audio Tone) transmitted by a Base Station on an analog voice channel and used to detect capture of a mobile station by an interfering Base Station or the capture of a Base Station by an interfering mobile station. Analog Control Channel A channel used for the transmission of digit control information from a Basε Station to a mobiiε station o from a mobile station to a Basε Station. Analog Paging Channel A forward analog control channεl that is usεd to pag mobilε stations and sεnd ordεrs. Analog Voice Channel A channεl on which a voicε conversation occurs an on which brief digital messagεs may bε sεnt from a Bas Station to a mobilε station or from a mobilε station to a Bas Station. Anchor - thε εlεmεnt which originally was serving the radio personal terminal o radio termination (RPT/RT) whεn thε RPT/RT rεquεstεd o was offεrεd a call from thε nεrwork. Thε anchor element maintains bearεr and/or control channεls to thε RPT/RT via sεrving εlεmεnts. Anchor PCSC Tnε Pεrsonal Communications Switching Centεr (PCSC) which controls the Base Station (BS), that is the first to assign a traffic channel to a call on origination or termination. For the duration of this call, this PCSC will be the anchor (fixed) point in the event that the Mobile Station (MS) should be handed off to other PCSCs. AUTH A 1 -bit field in thε Systεm Paramεtεr Overhead Messagε. Whεn sεt to 1 , it signifiεs that thε systεm supports thε authεntication procedures. Authentication A procedurε usεd by Basε Stations to validate a mobile station's identity at system access. Authentication Response (A UTEDR) An 18-bit output of the authentication algorithm. It is used to validate mobile station registrations, originations and terminations. Authorization Code - Authorization - Automatic Callback - Automatic Personal Derεgistration - thε procεss by which a user's location registration is automatically canceled without any explicit action from the user. Automatic Pεrsonal Rεgistration - the procεss by which a user's locatio registration is automatically updatεd without any explic action from thε usεr. Automatic Rεcall - Auxiliary Sεrvicεs - rεprεsεnt a variety of servicεs such as voicε mail, paging εtc. which may not bε providεd by thε PSC. Base Station A station in thε Domεstic Public Cεllular Radi Tεlεcommunications Sεrvicε, othεr than a mobilε station usεd for radio communications with mobilε stations. Base Station Authentication Response (AUTHBS) An 18-bit partεm gεneratε by thε authεntication algorithm. AUTHBS is usεd to confir thε validity of Basε Station ordεrs to update the Sharεd Secret Data. Base Station Random Variable (RANDBS) A 32-bit random numbe genεratεd by thε mobilε station for usε in authenticating Basε Station ordεrs to update thε Sharεd Sεcrct Data. Basic Tεlεcommunication Sεrvicε - A complctε set of capabilities that satisfies a specific telεcommunication rεquirεment, and which can be provided without the neεd of any additional sεrvicε. BCH Code Bosε-Chaudhuri-Hocqucnghεm Codε Bεarεr Channεls - Bεarεr Sεrvice - A type of telεcommunication service that provides the capability for the transmission of signals between user- nεtwork intεrfacεs. Bearer Services Telecommunications services Lhat provide the user with the capabilities, needed to transmit appropriate signals between certain access points (user-network interfaces). BER Bit Error Rate - Equals (0 of receivεd bit errors)/(Total 0 of transmitted bits). BIS S Identifies whether a mobile station must check for an idle-to- busy transition on a revεrsε analog control channεl when accεssing a systεm. Busy-Idle Bits Tne portion of the data stream transmitted by a Base Station on a forward analog control channel that is used to indicate the current busy-idle status of the corresponding revεrse analog control channel. Call Acceptance - the mechanism which allows a user to be alerted on on tεrminal and to choosε to answer thε call on any terminal, no necessarily the onε through which alεπing took placε. Call Delivery Method Mεthod by which a call is delivered to a subscriber i PCSC-V. Call Delivery Tne procεss by which calls dirεctεd to thε cεllular subscribε arε delivered to the subscriber while roaming in a visite system. Call Disconnect The process of rεquεsting thε releasε of a connection between two or more nεrwork addrεssεs. Call Forwarding Busy - Call Forwarding No Answer - Call Forwarding On Mobile Subscriber Busy - Call Forwarding On Mobile Subscribεr Not Rεgistεrεd - Call Forwarding On No Paging Rεsponsε - Call Forwarding On Radio Congεstion - Call Forwarding Unconditional - Call Hold - Call Managεmεnt - Destination Idεntification - thε procεss by which thε network identifies a wireless tεrminal or a wireline access location to which a call can be routed (eventually to die user) subsεquεnt to dεtεrmining that a called address is a UPT number. Call Managemεnt - Routing To Dεstination Tεrrninal(S)/Usεr(S) - thε procεss by which thε nεtwork sεts up thε connεction from the calling party to thε PCS usεr(s) via a wireless terminal or a wirelinε accεss location. Call Progrεss Tonεs - Call Release The process of relinquishing the facilities and circuits used for a call. Call Termination The process of connecting a subscriber to an incoming call. Call Trace - Call Transfer - Call Waiting - Call - An instance of a basic telεcommunication sεrvicε. Calling Numbεr Idεntification Presentation - Calling Number Idεπtification Rεstriction - Calling Numbεr Idεntification - Calling Party Numbεr - Candidate PCSC This term is used during the handoff mεasurεmεnt rεquεst b thε currεnt serving PCSC to refεrεncc thε PCSC that is bεin rεquεstεd to providε its bεst CELL ID and SIGNA QUALITY valuεs. CCLISTs Thε list of analog control channεls to bε scannεd by a mobil station procεssing thε Directεd-Rεtry Task (sεε 2.6.3.14). CDMA - Codε Division Multiplε Access; a radio access technique. Cell Site Tne physical location of a cell's radio equipment an supporting systems. This term is also used to refεr to th εquipmεnt located at the cell site. PCS Carrier A licεnsεε of thε rεsponsiblε govεmment agency (in the U.S. a licensεe of thε Federal Communications Commission) authorized to provide Personal Communications Services. CELP Code Excited Linear Prεdictivε Coding. Thεsε techniques use codebooks to vector quantize the excitation (residual) signal of a Linear Predictive Codec (LPC). Channel Quality Measurement (CQM) A digital message in two parts in which the results of mobile channel quality measurements are sent to a Base Station over the FACCH or the SACCH. Charging Indicator - Chipping - A wideband modulating signal's amplitude that changes continually between two states, high and low, arbitrarily called +1 and -1 , respectively. The sequencε of highs and lows is psεudo- random; that is , at εqually spaced intervals, control logic decides whether the wideband modulating signal should be +1 or -1. The logic chip altematεs the amplitudes so that they seem to be random— over a long enough period , the numbers of + l's and -l's are about equal-and they follow a pattern the rεcεivεr can recognize. The speed of alternation is called the "chip rate" bεcause dirεct- sεquence sprεad spectrum chops up, or "chips", bits Clearinghouse A service used for the exchange and managemεnt o information. Closεd Usεr Group (CUG) - CMAXs The maximum number of channels to be scanned by a mobil station when accessing a system. Code Administration Task Force A group of cellular industry reprεsεntativεs which will be responsible for coordination o the code assignments in accordance with thε provisions of this IS-53, undεr thε auspices of the Enginεεring Dεpartmεnt o thε E.IA. Codec Thε combination of an εncodεr and dεcodεr in series (encodεr/decoder). Coded Digital Verification Color Code (CDVCC) A 12-bit data field containing thε 8-bit DVCC and 4 protection bits, sent in each time slot to and from mobile stations and Base Stations. It is used to indicate that thε corrεct rathεr than co-channεl data is bεiπg dεcodεd. Coder Same as "encoder". Communication - The instancε of an application of a tεlεcommunication sεrvicε. Confεrεncε Calling - Confidεntiality - a propεrty by which intbrmation relating to an entity or party is not made available or disclosed to unauthorized individuals, entities or processes. Configuration Managεmεnt - providεs functions to exercisε control over, identify, collect data from, and provide data (i.e., provisioning data, service logic, etc.) to NEs. Connected Number Identification Presentation - Connected Number Identification Restriction - Connection Control - provides the allocation, de-allocation, and cross- connection of bearεr channels and management of associated resources and/or facilitiεs. Continuous Transmission A modε of opεration in which Discontinuous Transmission is not pεrmittεd. Control Mobile Attenuation Code (CM.AC) A 3-bit field in the Control-Fil Messagε that specifies the maximum authorized power le for a mobile transmitting on a reverse control channel. Coordinated Universal Timε - COUNTs-p A modulo-64 count hεld in thε mobilε station. COUNT s _ p maintained during power off. CPAs Identifies whethεr thε accεss functions are combinεd with t paging functions on thε samε sεt of analog control channεls. Cryptography [7498-2] - thε discipline which embodies principles, means an methods for the transformation of data in ordεr to hidε i information content, prevεnt its undεtεctcd modificatio and/or prevent its unauthorized use. CUG Only Facilities - CUG with Both Incoming and Outgoing Access - CUG with Incoming Access - CUG with Outgoing Access - Customer Originated Call Trace - Cyclic Redundancy Check (CRC) A process in which a desirεd sεquεnce o bits is εncodεd in a prεscribεd mannεr to εnablε detεction an corrεction of bit εrrors. In this Standard, certain critical bi sequεncεs are encoded using specified polynomials an procedures which use CRC- 16 (CCITT) and BCH cod structures. Data Communications The digital transmission of information (other tha voice). Data Message Handler (DMH) A configuration of equipment designed t • automatically exchange non-signalling data message between systems. dB SPL Sound Pressurε Lεvel in deciBels with respect to 0.00 dynes/cm 2 , 20 log _o(Prεssurε / 0.002 dynεs/cm 2 ). dBPa i prεferrεd. dBA A-weightεd sound prεssurε lεvεl expressed in dB obtained b the use of a metering characteristic and the weighting 'A spεcifiεd in ANSI S I .4- 1983, and thε addεndum ANSI S i .4a- 1985. dBmO Powεr relative to 1 mϋliWatt. CCITT Recommεndation G.71 1 spεcifiεs a thεorεtical load capacity with .a full scalε sinε wavε to bε -K3.17 dBmO for μ-Iaw PCM coding. In this standard, +3.17 dBmO is also dεfiπεd to bε thε lεvεl of a full amplitude sine wave in the 16 bit 2's complemεnt notation usεd for thε data files. dBPa Sound ievεl with rεspεct to 1 Pascal, 20 log i ( . (Prεssurε / 1 Pa). DCC S A DCC valuε stored in a mobile station's temporary memory. Deactivation - Decoder Generally, a device for the translation of a signal from a digital rεprεsεntation into an analog format. See also "transcoder". For the purposes of this standard, a devicε compatiblε with IS-54 §2.2.2.2.4. Dedicated Control Channels A channel used for the transmission of digital control information from εithεr a Base Station or a mobiiε station. Digit Delimiter The Digit Delimiter is the character '#', which is commonly known as the "pound", "sharp", or "number" key. Digit Sequence Some features may require that a Feature Code String include additional information which is the object of the feature - for examplε, Termination Addresses in Call Forwarding, Credit Card Charge information, Passwords, etc. Such additional information is refεrrεd to as a Digit Sequence. Digit Sequences are different from Modifier Digits, in that Modifiεr Digits are used to provide definition of options within a feature, while Digit Sequences are the object of the Feature's operation. Digital Color Code (DCC) A digital signal transmitted by a Base Station on a forward analog control channεl that is used to detect capture of a Base Station by an interfering mobile station. Digital Data Servicε (including facsimile) - Digital Data Servicε implies that non-modulated data is inserted directly into thε basεband timε slots and thus is sεnt at thε channεl bit ratε. If thε channεl bit ratε is faster than thε data ratε, thε placing of some type of information in thε extra time slots is called rate adaptation. The standards for rate adaptation includε V.1 10 which is a form of bit stuffing but where the stuffed bits carry Forward Error Correction information, V.120 which is byte stuffing, and X.3 1 which is flag stuffing. Digital Mobile Attenuation Code (DM.AC) A 4-bit field commanding the initial mobilε powεr level when assigning a mobile station to a digital traffic channel. Digital Verification Color Code (DVCC) A digital 8-bit codε that is sεnt by thε Basε ' Station to the mobile station and is used for the genεration of thε. CDVCC. Digits Digits consist of 0, 1 , 2, 3, 4, 5, 6, 7, 8, and 9. Dirεct Scquεncε Sprεad Spεctrum - Dircct-scquεncε transmission sprεads thε spεctrum by modulating the original baseband signal directly widi a very wide baseband digital signal. The wideband modulating signal's amplitude changes continually bεtwεεn two statεs, high and low, arbitrarily called ÷l and - 1 , rεspectivεly. Tne sequεncε of highs and lows is psεudo-random; that is , at εqually spacεd intεrvals, control logic dεcidcs whether the wideband modulating signal should be ÷l or - 1. The logic chip alternates the amplitudes so that they sεεm to bε random— ovεr a long enough period , the numbers of ÷l's and -l's are about equal-and they follow a pattern the receiver can recognize. The speed of alternation is called the "chip rate" because direct- sequence spread spectrum chops up, or "chips", bits. Discontinuous Transmission (DTX) A mode of operation in which a mobilε- station transmittεr autonomously switches between two transmitter power levels while the mobile station is in the conversation state on an analog voice channel or a digital traffic channel. Distinctive Alerting/Call Waiting - Do Not Disturb Fεaturεs - DTXs Idεntifiεs in what way thε mobile station is pεrmittεd to u thε discontinuous transmission modε on thε analog voic channεl. Duplεx Mεthod - Explains how two-way transmission is achiεvεd. Frεquenc Division Duplexing (FDD) means that the transmit an rεcεivε dirεctions use different frequεnciεs whilε Tim Division Duplεxing (TDD) mεans that both transmit an rεcεivε dirεctions use thε samε frεquεncy, but thεy takε rum in transmitting. This doεs εan that information has to b transmittεd at lεast twice as fast as "normal" and thεn slowε back down at thε receiving end. DVCCr A DVCC valuε rεcεived by a mobile station over the forwar digital traffic channel. DVCCs A DVCC value stored in a mobile station's temporar memory. Dynamic Range - The normal attenuation in both directions of transmissio between the Basε Station and thε Mobile Stations in a cell with a 20-30 mile radius means that bodi receivers must be capable of working ovεr a wide range of reccivεd signal strεngths. Whεn in tεrrain with physical obstacles such as buildings or mountains, "shadowing" can further attenuate the signal. Thesε problεms can bε overcome today with fast- reacting automatic gain control (AGC) circuitry which can be carried into the digital transmission arena. Tne digital cellular components now being introduced for mobile transceivers have an operating range of over 80 dB of received signal strength. Echo Cancellation - Emergεncy Sεrvices - any RPT/RT should bε allowed to make an emergency (e.g., 91 1) call. Emergεncy calls should have priority over all other calls to ensure service. Encipherment - the cryptographic transformation of data (sεε cryptography) to producε cipher text. Encoder Generally, a device for the coding of a signal into a digital reprεsεntation. For thε purposε of this standard, a dεvicε compatible with IS-54 §2.1.3.3.2. Encryption [7498-2] - sεε επciphεrment. Es The stored value of thε E field sεnt on the forward analo control channεl. E 5 identifies whethεr a homε mobile statio must sεnd only MINlp or both MINl and M_ 2p whε accessing the system. EXp Identifies whethεr homε mobilε stations must sεnd MINlp o both MIN lp and MIN2p whεn accessing the systεm. EX D differs from Es in that the information is stored in thε mobilε station's sεcuriry and idεntification mεmory. Extended Protocol An optional expansion of the signaling messagεs bεtwεεn thε Basε Station and mobilε station to allow for thε addition of nεw systεm fεaturεs and opεrational capabilities. Extension Phone Service - External Networks - rεprεsεnt othεr voicε, digital data, packεt data, and broadband data nεtworks. Fast Associated Control Channel (FACCH) A blank-and-burst channel used for.signaling message exchangε bεtwεεn thε Basε Station and thε mobile station. Fault Management - set of functions which eπablεs the dεtεction, isolation, and corrεction of abnormal operation of thε tεlεcommuπications network and its environmεnt. FDMA - Frεquεncy Division Multiple Access; a radio access technique. Feature Code String Feature Code Strings consist of the subscriber entered information (including an introducing '*' or '**', numeric Digits, and the Digit Delimiter '0') which is sent to the Serving Carrier's system to invoke or cancel a feature. Feature Codε String- Fεature Codε Strings consist of the subscribεr entered information (including an introducing '*' or '**', numeric Digits, and the Digit Delimiter '#') which is sent to the Serving Carrier's system to invoke or cancel a feature. Feature Codes Feature Codes are digit sequences entered by die subscriber to invoke special functions or non-standard modes of operation within the Cellular network. Featurε Deregistration - Fεaturε Dialing Procεdurεs - Feature Registration - FIRSTCHAs Tne numbεr of thε first analog control channεl usεd accεssing a systεm. FIRSTCHDs Tnε number for the first channel usεd as a dεdicatεd cont channel. FIRSTCHPp.pri The number of the first paging channel used as a prim paging channel in thε mobilε station's "home" systεm. FIRSTCHPp-sec Thε numbεr of thε first paging channεl usεd as a sεcond paging channε! in thε mobilε station's "homε" systεm. FIRSTCHPs Thε numbεr of thε first analog control channεl used paging mobilε stations. Flash Request A signal sent on a voice channel from a mobile station t land station indicating that a user dεsirεs to invoke spεc procεssing. Tnis is usually done by thε usεr dεprεssing t "SEND" kεy. Flash Request An indication sent on an analog voice channel from a mob station to a Base Station indicating that a user desires invoke special processing. Flash Request - A signal sent on a voice channel from a mobile station to land station indicating that a user desires to invoke speci procεssiπg. Tnis is usually done by the user depressing t "SEND" key. Flash with Information A message sent over the digital traffic channel in eith direction to indicate that special processing is required. Forward Analog Control Channel (FOC An analog control channel us from a Base Station to a mobile station. Forward Analog Voice Channel (FVC) An analog voice channel us from a Base Station to a mobile station. Forward Digital Traffic Channel (FDT A digital channel from a Ba Station to a mobile station used to transport user informati and signaling. There are two separate control channe associated with thε FDTC: the Fast Associated Contr Channel (FACCH) and the Slow Associated Control Chann (SACCH). Forward Error Correction - the use of redundancy bits to locate and corre transmission channel errors. Framing - Frequency Hopping Spread Spectrum - Geostationary (Geosynchronous) Orbit - A geosynchronous orbit is one wher the satellite appears to remain above a fixed spot on earth. O a plane passing through the equator, this occurs when th orbit is circular 22,300 statutε milεs abovε thε εarth Group Identification A subset of thε most significant bits of the syste identification (SID) that is used to identify a group of cεllula systεms. Group Idεntification - A subsεt of thε most significant bits of thε systε idεntification (SID) that is usεd to identify a group of cεllula systεms. Handoff Thε act of transferring a mobile station from one channel t another. Home Carrier / Home PCSC Tne PCS Carriεr from which mobilε subscribεr normally obtain service, and from which their permanεn Mobilε Idεntification Number is obtained. Home Location Register (HLR) The location register to which a user identity is assigned for record purposes such as subscriber information. Home Mobile Station A mobilε station that operatεs in thε cεllular system from which sεrvicε is subscribεd. Home System The system which is transmitting a SID which is recognized by the mobile station as the "Home" SID. Home System Tne system which is transmitting the SID which is recognized by the PSS as the "Home" SID. Home System - The database where a subscriber/user service profile, accounting information, etc., are permanently located. In-Progrcss Call Trace - Incoming Call Screening - Incoming Calls Barred Within CUG - Information Transfer Interfacε (Iti) - establishment of a communicatio (signaling) path and any required bearεr path bεtwεεn th RPT/RT and thε radio port. For εxamplε, in TDMA an FDMA, timε slots and frεquεncies are identified, and i CDMA, sequence codes are identified. Interrogation - Intersystεm Handoff - Intεrworking Functions - mεchanisms which mask the differεncεs in physical, link, and nεtwork tεchnologiεs into consistent network and user servicεs. Invocation - IRS Iπtεrmεdiatε Rεfεrεncε Systεm. See CCITT Rεcommcndation P.48 1 . Kεy Fεεdback Tonε - Last Numbεr Rεdial - LASTCHAs Thε numbεr of thε last analog control channel used for accessing a system. LASTCHDs Tne number for the last channεl usεd as a dεdicatεd control channel. LASTCHPs The number of the last analog control channel used for paging mobile stations. LOCALD s Thε rεceived location area identity. LOCA_D S -p Identifies the current location area. Location Registration (LREG)A 1-bit field used to indicate the location area ID registration status. LREGs The stored value of the LREG field received in the most recent Location Area Global Action Message. LT S Identifies whether the next access attempt is required to be the last try. MAXBUSYsI The maximum number of busy occurrences allowed on a revεrsε analog control channel. 5 CCITT, The International Telegraph and Telephone Consultative Committee, Blue Book, Vol. V, Telephone Transmission Quality, IXth Plenary Assembly. Melbourne. 14-25 November, 1988, Rcc. P.48, p.δ l fT. MAXSZTRsl The maximum number of sεizurε attempts allowεd on a reverse analog control channel. Mean Output Power is dεfinεd as thε calorimetric powεr mεasurεd during the active πart of transmission. Message Tπere are 2 types of messagεs sεnt betweεn Basε Stations and mobilε stations: ordεr mεssagεs and acknowledgement messagεs. .An ordεr mεssagε commands or requests the recipient to take somε action. In some casεs, the rεcipient acknowledges an order message by returning an acknowledgemεnt message. In other cases, no acknowledgemεnt mεssagε is rεfumεd. If a messagε has "Ack" as part of its name, it is an Ack Message; otherwise, it is an Ordεr Message. The following are exarnplεs of valid ordεr-mεssagε names: Send Burst DTMF, Send Burst DTMF Order, Send Burst DTMF Order Messagε, and Sεnd Burst DTMF Mεssagε. Tnε following are examplεs of valid acknowledgemεnt-mεssagε namεs: Send Burst DTMF Ack, Send Burst DTMF Ack Messagε, Measurement Order Ack, and Measurement Ordεr Ack Message. MINlp The 24-bit number that corresponds to the 7-digit directory telεphonε numbεr assignεd to a mobiiε station. MIN2p Thε 10-bit number that corresponds to the 3-digit area code assigned to a mobile station. MNRU Modulated Noise Rεference Unit. A procedure to add speech correlated noise to a speech signal in order to produce distortions that are subjectively similar to that produced by logarithmically companded PCM systems. The amount of noise is expressed as a Signal to Noise Ratio value in dB, and is usually referred to as dBQ. See CCITT Recommendation P.81 2 . Mobile Assisted Handoff (MAHO) A process where a mobile in digital mode, undεr direction from a Base Station, measures signal quality of specifiεd RF channels. These measurements are forwarded to the Base Station upon request to assist in the handoff process. 2 CCITT, The International Telegraph and Telephone Consultative Committee, Blue Book, Vol. V, Telephone Transmission Quality, IXth Plenary Assembly, Melbourne, 14-25 November, 1988. Rcc. P.8 I , p. l 9Sff. Mobile Directed Handoff (MDHO) - Mobile Identification Number (MTN) Tne 34-bit numbεr that is a digita representation of the 10-digit directory telephone numbe assigned to a mobile station. Mobile Identification Numbεr (MIN) - Thε 34-bit numbεr that is a digital represεntation of the 10-digit directory telεphonε numbεr assignεd to a mobile station. Mobile Protocol Capability Indicator (MPCI) A 2-bit field used to indicate thε mobilε station's capabilities. Mobile Station A station in the Domestic Public Cellular Radio Telεcommunications Service intended to be used while in motion or during halts at unspecified points. It is assumed Lhat mobile stations include portable units (e.g., hand-held personal units) and units installed in vehicles. Mobile Station Class Mobile station classes arc defined in Table 2.1.2-1. Modem-Modulatεd Data (including facsimile) - Modifier Digits The specific implementation of some features may accept or requirε additional information relative to the feature's operation - for examplε, the number of rings, or the time delay, associated with Call Forwarding-No Answer. In such cases, this information may be rεprcsented by inclusion of one, rwo, or three additional digits, known as Modifier Digits, in the construction of the Feature Code String.3 When only one Modifier Digit is used, the Digit '0' is a special casε, and is treated as provided in paragraph 1 1.2.3. Modifier Digits do not include those digits which are Digit Sequences. MOS Mean Opinion Score. The result of a subjective test based on an absolute category rating (ACR), where listeners associate a quality adjective with the speech samples that they are listening to. Thεse subjective ratings arc transferred to a numerical scale, and the arithmetic mean is the resulting MOS number. Multi-Level Precedence and Preemption - Multi-path Fading - Fluctuation in the resultant received radio signal level an phase due to the arrival of thε samε transmitted signal vi different paths with different amplitude and phas relationships. Multipath fading could result in thε rεcεivεd signal level falling below the receiver threshold or in distortion of the phasε information. Multiplε Accεss Tεchniquεs - Multiplε Accεss mεthodologiεs are of basically two typεs dεpεnding on how thε frequency is to be shared: 1.) Multiple-channcls-pεr-carriεr wherε multiple simultaneous user channεls arε multiplεxεd togεther within a givεn bandwidth (Frεquεncy Division Multiplεxing [FDM]) or bit- rate (Time Division Multiplexing [TDM] or Codε Division Multiplexing [CDM]) and 2.) Single-channcl-pεr-carriεr mεthods whεrε multiplε usεrs arε sequεntially givεn thε εntirε bandwidth (or bit-ratε) via a prε-arrangεd structure which is often referred to as "access protocol". Single-channel-pcr- cam ' εr tεchniqucs are more often seen in LAN or satellite applications than in voice and voice-gradε data applications εvεn though thε originating alerting tεchniquεs bεfore a channel is assigned in the circuit-switched environmεnt rεquirε somε typε of accεss protocol. 1.) Simultanεous Sharεd Transmission Mεdia (Muitiple-Channels-per- Carriεr) Accεss Protocol Frεquεncy Division Multiplε Access (FDMA) refers to a methodology where the bandwidth allocated to die service or provider is Frequency Division Multiplexed and De¬ multiplexed into several smaller bandwidd. channels and the control circuitry assigns one of these channels when there is demand. Time Division Multiple Access (TDMA) occurs when the FDM derived channels mentioned above (or another given bandwidth) is furthεr multiplexed using time as a parameter and the control circuitry assigns a time and frequency defined channel to a specific user to meet the demand. 206 Codε Division Multiple Access (CDMA) occurs when a pseudo random (PR) or other orthogonal code is used as multiplexing parameter and thε control circuitry assigns spεcific code to a specific user to meεt thε dεmand. Tn spreading codε, a varying sεquεncε of ÷ and - l 's sprεads th signal via amplitude or phase modulation. This varyin sεquεncε of ÷ and - l's is known as dirεct-sεquence sprεad spectrum and is sometimεs also known as Sprεad Spεctrum Multiple Accεss (SSMA). There can also be frεquεncy hopping CDMA. 2.) Sequentially Shared Transmission Media (Single-Channεl-pεr-Carrier) Access Protocol Sincε thε prototype servicεs for comparison are all multiple channεls pεr carriεr services (the Wirεless LAN portion of PCS is assumεd to bε thε rεspoπsibility of IEEE 802.1 1), only thε two most prevalent types of uplink and downlink signaling channel access protocol arc outlined. Aloha / Slotted Aloha The Aloha protocol is such a schεme that h impact in both satellite communications as well as in loc area networking and also works well when a mobile un wishes to originate and request a channel assignment. Alo is essentially a random, statistical method for assigning th bandwidth of a single channεl. All transmitting locations us a packεt protocol with all packets being the same size an thus any packεt occupiεs thε bandwidth for the same amou of timε as any othεr packεt. A station can transmit only on packεt at a time, but can transmit any time it wishes. If tw stations transmit at the same time, their packets collide an both packets are destroyed by mutual interference. When th recεiving station fails to acknowledge a packet, the sendin station acts as it does with any ARQ (Automatic Repεa rεQuεst) protocol in rε-sεnding the packet. To insure that re transmirtεd packets don't again collide, each transmitter wait randomly assigned interval before re-transmitting Improvements to the simple Aloha protocol have beεn mad including εarly collision dεtection; restricting transmission t only certain timε slots (slotted Aloha); assignment o priorities to give high volume traffic stations more timε allowing somε high volume stations to transmit with mor power so that in a collision situation thε high-power packε "wins"; εtc. Aloha was thε precursor of Carrier Sens Multiplε .Accεss / Collision Dεtεction which has bεε standardized as IEEE 802.3 (ISO 8802/3) and is commonl known as Ethemεt. Tnε othεr LAN accεss protocol standard are IEEE 802.4 (ISO 8802/4) Token Bus, IEEE 802.5 (IS 8802/5) Token Ring, IEEE 802.7 (ISO 8802/7) Slotted Ring. Packet Reservation Multiple Access (PRMA) is an extended version of Aloha for packet transmission. If the packets in the beginning of the train can secure the channel, a slot is resεrved for the subsequεnt packets. PRMA works well in a non-real-time environment and the queuing time is usually acceptable for downlink alerting. NBUSY S v The number of times a mobile station attempts to seizε a rεverse analog control channεl and finds thε rεverse control channel busy. Network Facility - thε connεctioπ between thε Radio Port Controllεr and th PCS Switching Cεπter. Network Reference Model The functional entities and the associatε intεrfacε rεfεrεncε points that may logically comprisε a PC nεtwork. Normal Charging - North Amεrican Numbεring Plan - Thε numbεriπg plan for thε North Amεrican public switched telεphonε network. N$ The number of analog paging channels that a mobilε station must scan. NSZTRsv Tnε numbεr of timεs a mobile station attempts to seize a reverse analog control channel and fails. Numeric Information Numeric information is used to describe the operation of the mobile station. The following subscripts are used to clarify the use of the numeric information: • "p" to indicate a value set in a mobilε station's pεrmanεnt sεcurity and idεntification mεmory, and • "r" to indicate a value received by a mobile station over a forward analog control channel, • "s" to indicate a valuε stored in a mobile station's tεmporary mεmory, • "s-p" to indicate a value stored in a mobilε station's semi-permanent security and identification memory. • "si" to indicate the stored limits on values that vary, • "sv" to indicate a stored value that varies as a mobile station processes various tasks, NXTREGs-p Identifies when a mobile station must make its next registration to a system. Opεrations, Administration, Maintεnancε, Provisioning (O.AM&P) Systems monitor, tεst, administer, and manage traffic and billin information for personal communications servicεs an systεms. Order Sεε dεfinition for Mεssagε. Originating PCSC Thε PCSC (usually thε PSS's homε PCSC) which rεcεivεs a call to bε dεlivεrεd to a PSS. Origination Call Tracε - Outgoing Call Barring - Outgoing Call Tracε - Outgoing Calls Barred Within CUG - Overload Control (OLC) A means to restrict reverse control channel accessεs by mobilεs. Mobilεs arε assignεd onε (or morε) of sixtεεn control levels. Access is selectively restrictεd by a Basε Station sεtting onε or morε OLC bits in thε Ovεrload Control Global Action Message. Paging Tne act of seeking a mobilε station when an incoming call has beεn placεd to it. PCI S Tne storεd valuε of the PCI field in thε System Parametεr Overhead Messagε. PCSC-G: A "gateway" PCSC is for further study. PCSC: Tne primary switching & control point used by the PCS nεtwork to control access to the PSTN. PCSC-H: The "home" PCSC of a PSS which is broadcasting the SID that is rεcordεd in thε PSS's Security and Identification memory and which also is the "ownεr" of the directory number from which the PSS's MIN (refer to EIA TlA-553) is derived. PCSC-V A "visited" PCSC in whose service area a roamer is operating. PDREGs Tne stored value of the PDREG field received in the most recεnt Location Arεa Global Action Message. Performance Managemεnt - providεs functions to εvaluate and rεport on thε bεhavior of telecommunications equipment and the effectiveness of the network or network elemεnt (NE). Pεrsonal Communications Access Hunting - Personal Communications Location Service - Personal Communications Switching Center (PCSC) supports acces indεpεndεπt call/sεrvice control and connection contro (switching) functions and is responsible for interconnεction o accεss and nεtwork systεms to support end-to-end servicεs Thε PCSC rεprεsεnts a collεction of one or more network elements. Note: The term "cεntεr" doεs not imply a physical location. Pεrsonal Communications Tεrmina! Locator - Pεrsonal Dεrεgistration - the process by which end users cancel a previous registration to a tεrminal. Personal Identification Number (PIN) A sεcrεt numbεr managεd by thε systεm opεrator for εach subscriber. The PIN is intendεd primarily for usε in authenticating the subscriber (a number used in the verification of a user's claimed identify). Pεrsonal Mobility Controllεr - providεs the control logic for user authεntication, sεrvicε rεquεst validation, location managεmεnt, alerting, usεr accεss to sεrvicε profile, privacy, access registration, and call management. Personal Mobility Data-Store - maintains data associated with users. Personal Subscriber Station (PSS) A genεric tεrm used to refer to equipmεnt such as mobile stations, mobile terminals, portables, and fixed personal subscriber stations. Physical Layer Controll A digital-mode-base-station control message to initiate or change certain mobile parameters such as traffic channel power, time alignment, and whether discontinuous transmission (DTX) is permitted. PL S The mobile station RF power level. Position Determination - the capability of determining geographic coordinates/location based on measurements received from a wirelεss device. Power Down Registration (PDREG) A 1-bit field used to indicate the power down registration status. Power Up Registration (PUREG) A 1-bit field usεd to indicate the power up registration status. Precεdence - Prεεmption - Prεfεrεntial Closεd Usεr Group - Primary Paging Channels A forward analog control channεl that is usεd to pagε mobile stations and send orders, and is supportεd by both EI.A-553 and IS-54 compatible mobilεs. Priority Accεss and Channεl Assignment - Privacy .And Authentication Managεmεnt - functions to cnsurε thε validity of both maintεπancε information and tεlecommunications network traffic key managemεnt, intrusion surveillance, and fraud control. Privacy Mode (PM) A one-bit parameter used to refεr to thε voicε privacy status: O' = "off . T = "on". Privacy - thε provision of protεction of usεr information intεndεd to prεvent access to such information by unauthorized parties. Clarification: This dεfinition pεrtains specifically to air intcrfacε aspεcts as discussed in thε draft proposed technical report "Privacy and Authentication Objectives for Wireless Access to Personal Communications". Protocol Capability Indicator (PCI) A 1-bit field in the first word of the System Parametεr Ovεrhεad Mεssagε that when set to one indicates the Base Station is capable of digital operation. PUREGs The stored value of the PUREG field received in the most recεnt Location Arεa Global Action Message. PLTREGs-p The semi-pεrmanent valuε of PUREG S . Quality of Service - Radio Access System Controller - supports the wireless mobility management and wireless access call control functions. It serves one or more subtending radio port controllers and may be associated with one or more PCS switching centers. Radio Channel (Link) - the spεcific bearer/signaling connection established between the terminal and the Radio Port Intermediary via the Radio Port. The nature of the radio channel is dependεnt on thε radio tεchnology. Radio Channel Identifier - a code managed by a radio port intermediary t distinguishes a radio connection between a RPT/RT and radio port interrnεdiary. Radio Channel Privacy - a treatment applied to signaling or usεr data which intεndεd to prεvent an unauthorized detεctor of thε data fro εxtractin Όg information. Note: See also εncryption. Radio Control Channεl Managεmεnt - nεtwork providing system information t terminals for the purpose of terminal location registration an call set-up. Radio Facility - thε bearer/signaling connεctioπ bεtwεεn thε Radio Po Intεrmediary and the Radio Port Controller. Radio Intεrfacε - Tnε common boundary bεtwεεn thε mobile station and th network, definεd by functional characteristics, common radi (physical) interconnεction charactεristics, sign characteristics, and other characteristics, as appropriat Note - An intεrfacε is usεd to specify once th interconnection betweεn thε two sidεs of it. Thε spεcificatio includεs thε type, quantity and function of the interconnectin means and the type, form and sequencing order of the signal to be interchangεd by those mεans. Radio Pεrsonal Tεrminal - a light-weight, pocket-size portable radio termina providing the capability for the user to be either stationary o in motion while accessing and using telecommunicatio services. Radio Port - supports transmission of signals over the air interface. Radio Port Controller - provides an interface between one or more subtendin radio port intermediaries and a PCS switching center, an supports air intεrfacc independent radio frequenc transmission and recεption functions. Radio Port Intermediary - providεs an intεrface betwεen one or more subtεndin radio ports and thε radio port controller, and supports ai interface depεndεnt radio frεquency transmission an reception functions. Radio Termination - interfaces terminal εquipmεnt to thε radio access interfacε. Random Variable (RAND) A 32-bit random number issuεd pεriodically by thε Basε Station in rwo, 16-bit piεcεs: RAND1_A and RAND 1_B. Thε mobilε station storεs and usεs thε most rεcεnt vεrsion of RAND in thε auihεntication procεss. Random Variable Confirmation (RANDC) A 8-bit numbεr usεd to confirm thε last RAND rεcεivεd by thε mobilε station. RAND S Thε storεd valuε of RAND. RCFs Idεntifiεs whεthεr thε mobile station must read a Control- Fillεr Mεssagε bεforε accεssing a systεm on a rεvεrsε analog control chanπεl. Rεdirecting Numbεr Idεntification - Redirεcting Numbεr - R£GID S Thε storεd valuε of thε last rεgistration numbεr (R£GID r ) rεcεivεd on a forward analog control channel. REGINCRs Idεntifiεs incrεmεnts bεtwεεn rεgistrations by a mobilε station. Registration Thε procεdurε by which a PSS bccomεs listed as being prεsεnt in the service arεa of an PCSC. Registration Thε stεps by which a mobilε station idεntifiεs itself to a Base Station as bεing active in the system at the time thε mεssagε is sent to thε Basε Station. Release Request A mεssagε sεnt from a mobilε station to a Base Station indicating that thε usεr dεsirεs to disconnect the call. Reordεr Tonε - Rεpeat Dialing - Reverse Analog Control Channel (RECC) The analog control channel used from a mobile station to a Base Station. Reverse Analog Voice Channel (RVC) The analog voice channel used from a mobile station to a Base Station. Revεrse Charging - Reverse Digital Traffic Channel (RDTC) A digital channel from a mobi station to a 3asε Station usεd to transport usεr informati and signaling. There are two sεparatε control channε associated with the RDTC: the Fast Associated Contr Channel (FACCH) and thε Slow Associatεd Control Chann (S.ACCH.) Roamer A mobile station that opεratεs in a cellular system other th the one from which sεrvicε is subscribed. Roamer Service Profile Thε spεcific sεt of fεaturεs, capabilities and/ operating restrictions, other than financial accountabilit associated with the subscribεr. Roamer Validation That aspect of roamer service qualification dealin with financial accountability. Also, the general procedure b which a roamεr's financial accountability is cstablishεd. Roamεr - A mobilε station that opεratεs in a systεm othεr than thε onε fro which sεrvicε is subscribεd. Roaming - ROLR Recεivε Objective Loudπess Rating. Thε rεceive audi sεnsitivity is thε ratio of thε input signal to a referenc encodεr to thε acoustic output of thε rεcciver exprεssεd as Receive Objective Loudness Rating (ROLR). ROLR(PN-2745) Receivε Objective Loudness Rating, a measure of receiv audio sensitivity. ROLR is a frequεncy-weighted ratio of th line voltage input signal to a reference encoder to the acousti output of the receiver exprεssεd as a Receive Objectiv Loudnεss Rating (ROLR). IEEE 269 defines the measuremen of sensitivity and IEEE 661 defines the calculation o objective loudness rating. Routing Address Or Routing Number - a(n) address (number) used by thε nεtwork to dirεct a call. R s Indicates whethεr registration is enabled or not. Scan of Channels Tne procεdure by which a mobile station examinεs the signal strength of each forward analog control channel. SCCs A digital numbεr that is stored and used to identify which SAT frequency a mobile station should be receiving. SDCCls The SDCC value stored in a mobile station's temporar memory. SDCC2s Trie SDCC valuε stored in a mobile station's temporary memory. Secondary Control ChaππelsA supplεmεntary sεt of analog control channεls dεveloped specifically for IS-54 compatiblε mobilε stations. Such channεls arε usεd for thε transmission of digital control information from εithεr thε basε or mobilε stations. Secondary Paging Channels In addition to the primary paging channels, a supplemεntary sεt of analog control channεls dεvεloped specifically for IS-54 compatible mobile stations. Such channels are used to page mobilε stations and sεnd ordεrs. Security audit trail [7498-2] - data collεctcd and potεntially usεd to facilitate a security audit. Security audit [7498-2] - an indepεndεnt rεviεw and εxamination of systεm rεcords and activities in order to test for adequacy of system controls, to ensurε compliance with establishεd policy and operational procedurεs, to dεtεct brεachεs in sεcurity, and to rεcommcnd any changes in control, policy and procedures. Seizure Precursor The initial digital sequεncε transmittεd by a mobilε station to a Basε Station on a rεvεrsε analog control channεl. Sεlεctive Call Acceptance - Selεctivε Call Forwarding - Sεlεctivε Call Rεjection - Servicε Accεss - the ability for thε nεtwork to provide access to featurεs to usεrs and accept sεrvice requests by users specifying the type of bearεr or supplementary service that the users want to receive from the PCS network. Service Feature Mediation And Compatibility - the process of correlating the capabilities of network elements with the service profiles of users and terminals and the terminal's capabilities for purposes of negotiating to deliver servicε fεaturεs and avoiding sεrvicε intεractions that lead to unexpected results. Service Qualification The sεrvicε capabilities, featurεs and privilεgεs t which a PSS is entitled. Also, the genεral procεdure by whic such sεrvicε capabilities, fεaturεs, and privileges becom εstablishεd in an PCSC. Sεrvicε Validation (Tεrminal) - thε procεss by which thε nεrwork authorizεs th dεlivεry of rεquεstεd capabilitiεs aftεr dεtεrmining th terminal's entitlεmεnt basεd on rεviεw of its sεrvicε profil and/or account status. Service Validation (User) - the process by which the network dεtεrminεs whεthε a usεr is allowed to receive servicε based on review of its service profile and-Or account status. Serving Carrier / Serving PCSC The PCS Carrier on whose RF facilities the Mobile Subscriber is obtaining service. Serving PCSC The PCSC which currently has the PSS obtaining servicε at onε of its cεll sitεs within its covεragε arεa. Sεssion kεy - an επcryption kεy which providεs privacy during a call and may bε changεd dynamically by thε system. Shared Secret Data (SSD) A 128-bit pattern stored in the mobile station (in semi-pεrmanεnt mεmory) and known by the Basε Station. SSD is a concatenation of two 64-bit subsets: SSD-A, which is used to support thε authεntication proccdurεs, and SSD-B, which sεrvεs as one of the inputs to the voice privacy mask generation process. Shared Secret Data is maintained during power off. Shared Secret Data Random Variable (RANDSSD) A 56-bit random number gεnεratεd by thε mobilε station's home systεm. RANDSSD is usεd in conjunction with the mobile station's A-key and ESN to generate its Shared Sεcrεt Data. Sidεtonε - SDDp The home system idεntification storεd in the mobile station's permanent security and identification memory. SID r The systεm idεntification received on a forward analog control channel. SIDs Tne stored system identification. SIDs-p Idεntifiεs thε systεm of currεnt (last successful) rεgistration. Signaling Tone A 10-kHz tone transmitted by a mobile station on an analo voicε channεl to: 1) confirm ordεrs, 2) signal flash rεquεst and 3) signal rεlεasε rεquεsts. Signalling: Tnε information exchanged between the mobile station an thε nεrwork, or within thε network, for the purposes of sεrvic provision (ε.g. connection establishmεnt). Slow Associated Control Channel (SACCH)is a continuous channel used fo signaling mεssagε exchange between the Base Station and th mobile station. A fixed number of bits are allocated to th SACCH in each TDMA slot. SNR Signal to Noisε Ratio. Thε ratio of powεr of a signal and thε powεr of a noisε or error signal that has bεεn addεd to it. Tnε SNR is often expressed in dεciBεls (dB), calculatεd as 10 logi o(SNR). SNR - Signal to Noisε Ratio. Thε ratio of power of a signal and thε powεr of a noisε or εrror signal that has bεεn addεd to it. Thε SNR is oftεn εxprεssεd in decibels (dB), calculated as 10 Iogi o(SNR). The signal to noise ratio in decibεls for a timε sεgmεnt, ; ' . A sεgrnεπt size of 5 mS is used, which corresponds to 40 samples at an 8 kHz sampling rate (seε§2.1.1 of IS-54). SNR/ (PN-2745) Tnε signal to noisε ratio in dεciBεls for a timε sεgmεnt, /. A sεgmεnt size of 5 ms is used, which corresponds to 40 samples at an 8 kHz sampling rate (sεε§2.1.1). SNRSEG Sεgmental signal to noise ratio. Tne weighted average over all time sεgmεnts of SNR / -. (sεε §2.1.1). Spεεd Calling - Sprεad Spectrum - Spread spectrum refers to a variety of techniques fo converting the information normally carried in a narrow ban tεlεcommunications channel to that suitable for transmissio over a much wider band of radio (or higher) frequεnciεs. A thε rεcεivεr the information carried in the broad range o frequεnciεs is converted back to the original narrow ban frεquency or thε information carried thεrεin Thε two main spread-spectrum tεchniquεs are dirεct-sεquεnc sprεadiπg, basεd on dirεctly modulating a data stream with a higher rate codε sεquεncε for spεctrum εxpansion; and frεquεπcy-hopping spreading, based on hopping the data stream in thε frεquεncy domain as a function of a codε sεquεnce for spεctrum εxpansion. Both tεchniqucs sprεad thε transmitted powεr over a widε frεquεncy band so that thε avεragε powεr pεr unit bandwidth (Warts pεr Hεrtz) is vεry small. At thε rεccivεr thε signal is comprεssεd into its original narrow band whilε leaving the power of any interfering signals scartεrεd over the wide transmission band. The key to success in this operation is that the signal meant for any given user is "tagged" with a direct-sequencε or frequency-hopping pattern that only that user's receivεr rεcognizcs. S s Idεntifiεs whεthεr thε mobilε station must sεnd its serial number when accessing a system. Status Information The following status information is used in this section to describe mobile station operation: • First Idle ID Status. A status variable used by the mobile station in association with its processing of the Idle task. • First Location Area ID Status. A status variable used by the mobile station in association with its processing of recεivεd Location Area ID messages. • First Registration ID Status. A status variablε usεd by the mobile station in association with its processing of received Registration ID messages. • Local Control Status. Indicates whether a mobile station must respond to local control messagεs. • Location Registration ID Status. A status variable usεd by thε mobilε station in association with its procεssiπg of powεr up rεgistrations and location-basεd rεgistrations. • Roam Status. Indicatεs whεthεr a mobile station is in its home systεm. • Serving-System Status. Indicates whethεr a mobilε station is tunεd to channels associated with System A or System B. Tεrmination Status. Indicatεs whεthεr a mobilε station mus tεrminatε thε call when it is on an analog voice channel. Subscriber Review .And Modification Of User Profile - thε ability for subscribεr, acting on bεhalf of a usεr of thεir servic subscription, to bε ablε to accεss the network to check o update their users' service profile(s) through mechanized access using uniform procεdurεs and codεs. Supervisory Audio Tone (SAT) One of three tones in the 6-kHz region that are transmitted by a Base Station and transponded by a mobile station. Supplementary Digital Color Code (SDCCl, SDCC2) Additional bits assignεd to incrεasε thε numbεr of color codes from four to sixty four, transmitted on the forward analog control channel. Supplεmεntary Sεrvicε - A sεrvicε that modifies or supplements a basic service. Note: A supplementary servicε cannot bε offered to a user as a stand-alone service. It must be offered with or in association with a basic telecommunication service. Switch Identification (SWID) A parametεr which is the concatenation of SID with SWNO. Switch Number (SWNO) A number uniquely identifying a particular switch within a group of switches associated with a common SID. Symbol In thε = DQPSK modulation schemε spεcificd, εach symbol carriεs 2 bits of information. Synchronization (of session key) - agreεmεnt bεtwεεn rεcεivεr and transmitt on a common rεfεrεncε point in a sεssion key. System Identification (SID) A digital idεntification associatεd with a cεllul system; each system is assigned a unique number. Target PCSC Tnε PCSC which was sεlectεd from thε candidatε list having thε cεll sitε with thε bεst signal quality valuε for t PSS during thε location rεquεst function. TDMA - Timε Division Multiplε Accεss; a radio accεss tεchniquε. Tεlεcommunication Sεrvice - A sεt of capabilities that satisfy tεlεcommunication requirement. Telεsεrvice - A type of telεcommunication sεrvicε that providεs thε complεt capability, including tεrminal εquipmεnt functions, fo communication bctwεεn usεrs according to establishe protocols. Teleservices Telεcommunication servicεs that providε the user wit necessary capabilities including tεrminal εquipmεπt function to communicatε with any othεr usεr's tεrminal εquipmεnt. Tεrminal Alεrtiπg - thε procεss of obtaining thε attention of a terminal by th network to deliver a call or other mεssagε. Note: This is rεfεrrεd to as "paging" in somε other systεms. Tεrminal Capability Verification - the process by which the network, if possible vεrifies whether die terminal, identifiεd by the tεrminal ID can support the requεsted service. Terminal Derεgistration - thε process by which a wireless terminal's previou location registration is canceled. Terminal Elements - terminal equipmεnt, radio terminations, terminal adapters data circuit-terminating equipment, and radio personal tεrminals. Tεrminal Equipmεnt - supports services for personal communications users via wirelεss or wireline access. Terminal Group Identifiεr- idεntifiεs the service group of which the terminal is membεr. Tεrminal Idεntifiεr Rεcognition - thε nεtwork capability to dεtεrmine tha information entεrεd by calling partiεs or rεcεived from othe networks is a terminal idεntifiεr. Tεrminal Mobility Controllεr - provides thε control logic for tεrmiπ authεntication, location management, alerting, and routing t RPT/RTs. Tεrminal Mobility Data-Storε - maintains data associatεd with terminals. Termination Address Onε or morε digits, as dεtεrminεd by thε Servin Carrier's system, which identify one (and only one Terminating Subscriber. This could includε Spεεd Call Codε (whεn supportεd by thε Serving Carrier), other Mobil Tεlephonε Numbers, or any valid World Teiεphone Number. Termination Call Trace - Three-way Calling - Tma The maximum undistortεd sinusoidal level that can be transmitted through the interfaces betweεn thε VSELP codεc and PCM basεd nεtwork. Tnis is taken to be a refεrεncε lεvεl of ÷3.16 dBmO (sεε IS-55 §2.2.4.1 and §3.3.2.2.1) TOLR (PN-2745) Transmit Objεctivε Loudπεss Rating, a measure of transmit audio sensitivity. TOLR is a frequency-weighted ratio of the acoustic input signal at the transmitter to the line voltage output of thε rεfεrεncε dεcodεr expressed as a Transmit Objective Loudness Rating (TOLR). IEEE 269 definεs thε mεasurεmεnt of sεnsitivity and IEEE 661 dεfinεs thε calculation of objective loudness rating. TOLR Transmit Objective Loudness Rating. The transmit audio sensitivity is the ratio of the acoustic input signal to the transmitter to the acoustic output of the reference decodεr εxpressed as a Transmit Objective Loudness Rating (TOLR). TOLR - Transmit Objective Loudness Rating, a measure of transmit audio sensitivity. TOLR is a frequency-weighted ratio of thε acoustic input signal at the transmitter to the line voltagε output of thε rεfεrεncε dεcoder expressed as a Transmit Objective Loudness Rating (TOLR). IEEE 269 defines the measurεment of sensitivity and IEEE 661 defines the calculation of objective loudness rating. Traffic Channel Tnat portion of the digital information transmitted betweεn thε Ba≤ε Station and thε mobilε station, or between the mobile station and thε Basε Station, mat is dεdicatεd to thε transport of usεr and signaling information as dεpictεd in thε figurε below. * FACCH and user information cannot be sent simultaneously. Traffic: Tne information genεratεd by thε subscribεr that i transported on the network (i.e. user voice or data). Transcoder A devicε that transforms signals from one type of digita reprεsεntation to anothεr. Transcoder - A devicε that transforms signals from onε type of digita rεprεsεntation to anothεr. Trεllis Coding - (Vitεrbi Algorithm) Trεllis coding adds a calculatεd fifth bit t εach QAM four-bit sequence. This extra bit when corrεlatε with previously rεcεived data sεquεncε hεlps thε rεccivin modεm to identify the phase and amplitude of the newly arrived carrier more accurately. Thε modems using QA includε V.22 bis, V.29, V.32, and V.32 bis. Uniform Sεrvicε Fεaturε Delivery - the capability to providε accεss to subscribεd nεtwork-basεd fεaturεs and sεrvicεs (ε.g., call waiting, call forwarding, thrεε-way calling, abbreviated dialing, othε ISDN sεrvicεs and supplementary services, etc.) in a uniform manner basεd on tεrminal capabilitiεs. Unique Challenge Authentication Response (AUTHU) An 18-bit pattern generated by the authentication algorithm. AUTHU is used to support the Unique Challenge-Response procedure. Unique Challenge-Response Procedure An exchange of information betwεεn a mobilε station and a Base Station for thε purpose of confirming the mobile station's identity. The procedurε is initiatεd by thε Basε Station and is charactεrizεd by the use o a challenge- specific random number (i.ε., RANDU) instεad of the random variable broadcast globally (RAND). Unique Random Variable (RANDU) A 24-bit random number genεrated by the Base Station in support of the Unique Challenge-Response procedurε. Usεr Alerting - the process of obtaining the attention of an end user by th network to deliver a call or other messagε. Usεr Idεntifiεr Rεcognition - thε nεtwork capability to dεtεrmiπε tha information enterεd by calling partiεs or rεcεived from othe networks is a user idεntifiεr (UPT numbεr). Usεr Privacy - protection of information about users from uninvitεd and possibly illegal access. User Profilε - includεs the sεrvicε profile and contains all the data associated with the usεr, ε.g., incoming call handling information, sεlεction of sεrvicε provider/service arεa covεragε, sεrvicε subscriptions, sεrvicε paramεtεrs, εtc. Usεr Rεviεw And Modification Of User's Profile - the ability for a user to bε ablε to accεss thε nεrwork to check or update their service profile through mechanized accεss using uniform proccdurεs and codes. User-to-user Signaling - Visited System: From the PSS's perspective, a systεm which is transmitting a SID which is not rεcognizcd by the PSS as the "Home" SID. Visited Systεm: - From thε MS's perspective, a system which is transmitting a SID which is not recognized by the MS as the "Home" SID. Visitor Location Register (VLR) The location registεr othεr than thε HLR usεd by an PCSC to rεtriεvε information for, for instancε, handling of calls to or from a visiting subscribεr. Visitor Location Rεgistεr (VLR) - Thε database wherε thε nεcessary information about a visiting user is copiεd from the user's HLR and temporarily stored for the purposes of providing personal communication services. Vocoding (voice encoding) - Voice Activated Features - Voice Mobile Attenuation Code (VMAC) A 3-bit field in the Extended Address Word commanding the initial mobile power level when assigning a mobile station to an analog voice or traffic channel. Voice Privacy Thε procεss by which usεr voice transmitted over a digital traffic channel is afforded a modεst dεgrεε of cryptographic protεction against eavesdropping in the mobile station - Base Station segmεnt of thε connεction. VSELP Vector Sum Excited Linear Predictivε coding. A form of CELP that specially structures the codebooks in order to reducε comDlexirv. Wait-for-Overhead Message (WFOM) A 1-bit field in the Control-Filler Messagε that whεn sεt to onε causεs thε mobilε to wait for an overhεad message before transmitting on a reverse control channεl. WER (PN-2745) Word Error Ratε - Equals (0 of incorrect recεivεd words)/(Total .- of transmitted words). Incorrect words are defined as having a Cyclic Redundancy Codε (CRC) chεck which fails. WER Word Error Ratε - Equals (~ of incorrect recεivεd words)/(Total = of transmittεd words). Incorrect words are defiπεd as having a CRC chεck which fails. WFOM Idεntifiεs whεthεr a mobilε station must wait for an Ovεrhεad Mεssagε Train bεfore accessing a system on a reverse analog control channel. World Numbering Plan - World Zone 1 - RF Link Protocol Architecture D5. RF Link Layer, Version 2T.X D5.1. Loop Format D5.1.1. Loop Format Normal Each normal polling loop is formed of sixty four Time Division Multiple Access (TDMA) time slots which are paired into thirty two TDMA frames where duplexing is accomplished by providing Time Division Duplexing (TDD) within each TDMA frame ("Version 2.T.X). The slots are not numbered. For the purpose of all documentation on Version 2T.X the word "slot" will refer to the above pair. Numbers are shown in table XXX for refεrεnce only. Proper slot synchronization is performed by timing. D5.1.2. Loop Format Extended for 10 Mile Range An εxtεnded rangε polling loop is forrπεd of 25 Timε Division Multiplε Accεss (TDMA) timε slots whεn duplexing is accomplished by providing Time Division Duplexing (TDD) within each TDMA slot in Version 2T.X. Tnε slots arε not numbεrεd. Numbεrs arε shown in tablε XXX for rεfεrεncε only. Tnerε is no indεx associatεd with thε polling loop. Propεr slot synchronization is pcrformεd solεly by timing. D5.2. Slot Format D5.2.1. Composite Slot Frame Each slot frame is composed of six elεmεnts and contains the complete transaction betweεn a Base and a Mobile Station. P-..2.1.1. Base Frame R . ,2.1,1,1. Base Frame Types Thεrε arε two major typεs of framεs transmittεd from the Base to the MS, Base Poll Frames and Base Traffic Framεs. D 2. 1 . 1 .1 . 1 . Base Poll Frame Basε Poll Framεs arε usεd to allow MS's to sεizε slots. D5.2.1.1.1.1.1. General Thε Gεnεral Basε Poll framε is an invitation to any MS to attεmpt to sεizε a slot. Tnis DOII indicatεs a free slot. D5.2.1.1.1.1.2. Specific The Specific Base Poll is an invitation for only the MS identified by the PID Information Element to seize the current slot. D5.2. 1 1 . 1 .7. Base Traffic Frame There are two basic types of Base Traffic Frame, Bearεr traffic and Signaling traffic. Each typε of Ba≤ε Traffic Framε εxists in thrεε variεtiεs, high bandwidth, low bandwidth and symmεtric bandwidth. Bcarεr Traffic also exists in thε broadcast variεty. D5.2.1.1.1.2.1. High Bandwidth Bearer High Bεarεr Traffic Framεs arε usεd to transport usεr traffic from thε Basε to thε mobile station. Thεrε arε two typεs of bεarer traffic FCW or error controlled traffic and RAW or not error controlled traffic. D5.2.1.1.1.2.1.1. FCW FCW or Frame Check Word traffic is error controlled. Errors dεtεctcd by thε FCW will bε corrεctεd by rε transmission. FCW framεs may bε tεmporally distortεd. D5.2.1.1.1.2.1.2. RAW RAW frames are transported without any error correction. Error correction is die responsibility of the PCS sεrvice operator application. D5.2.1.1.1.2.2. High Bandwidth Signaling High bandwidth Signaling Traffic framεs arε usεd to carry high spεεd systεm signaling from thε Basε to thε MS. Thεsε framεs contain a FCW. Error control and rεtry arε dεpεndεnt upon thε signaling sεquεncε taking placε at thε timε. D5.2.1.1.1.2.3. Low Bandwidth Bearer Low bandwidth Bearεr Traffic Framεs arε usεd to transport a small amount of usεr traffic from thε Basε to thε mobilε station. Thεrε are two typεs of bearεr traffic FCW or error controlled traffic and RAW or not error controlled traffic. DSC 1.1.1.2.3.1. FCW FCW or Frame Check Word traffic is εrror controlled. Errors detectεd by thε FCW will bε corrected by re transmission. FCW frames may be tεmporally distortεd. DSC 1.1.1.2.3.2. RAW RAW frames are transported without any error correction. Error correction is the responsibility of the user. DS.2.1.1.1.2.4. Low Bandwidth Signaling Low bandwidth Signaling Traffic frames arε usεd to carry small amounts of systεm signaling from thε Basε to thε MS. Thεsε framεs contain a FCW. Error control and rεtry arε dεpεndent upon the signaling sequεncε taking placε at thε time. DS.2.1.1.1.2.5. Symmetric Bandwidth Bearer Symmetric bandwidth Bearεr Traffic Framεs arε usεd to transport normal usεr traffic from the Base to thε mobilε station. Thεrε arε two typεs of bεarεr traffic FCW or error controlled traffic and RAW or not εrror controllεd traffic. DS.2.1.1.1.2.5.1. FCW FCW or Framε Chεck Word traffic is error controlled. Errors detectεd by thε FCW will bε corrεctεd by rε transmission. FCW frames may bε tεmporally distortεd. DS.2.1.1.1.2.5.2. RAW RAW frames are transported without any error correction. Error correction is thε responsibility of the user. D5.2.1.1.1.2.6. Symmetric Bandwidth Signaling Symmetric Signaling Traffic framεs are used to carry normal system signaling from the Basε to thε MS. Tnεsε framεs contain a FCW. Error control and rεtry are dεpεndeπt upon the signaling sequencε taking place at the timε. DS.2.1.1.1.2.7. Broadcast Bearer Bearεr Traffic Framεs arε usεd to transport usεr traffic from thε Basε to multiplε mobilε stations. Thεrε is only onε typε of broadcast bεarεr traffic that is RAW traffic. Forward εrror control on this traffic is thε responsibility of thε application. DS.2.1.1.1.2.7.1. RAW RAW framεs arε transported without any error correction. Error correction is thε responsibility of the PCS servicε opεrator application. D5.2.1.2. Mobile Station Frame P5.2.1.2,,- __ Mobile Station Frame Types There are two major types of frames transmitted from the MS to the Base, MS Poll Response Frames and MS Traffic Frames. P5.2 1 .7. 1 .1 Mobile Station Poll Frame Mobile Station poll framεs arε sεnt by a MS to thε Basε in responsε to a Basε Poll Framε as part of thε slot seizing sequencε. DS.2.1.2.1.1.1. General Response The General MS Poll Framε rεsponsε is usεd by thε MS to attεmpt to acquire a freε slot. D5.2. 1 .2. 1 .2. Mobilε Station Traffic Framε Thεre are two typεs of MS Traffic Framε, Bεarεr traffic and Signaling traffic. Each of these type εxists in thrεε variεtiεs, high bandwiddi, low bandwidth and symmεtric bandwidth. D 5.2.1.2.1.2.1. High Bandwidth Bearer High Bandwidth Bεarεr Traffic Frames are used to transport high speed user traffi from thε MS to thε Basε. Thεrε are two typεs of Bεarεr traffic, FCW or error controllεd traffic and RAW or error uncontrollεd traffic. DS.2.1.2.1.2.1.1. FCW FCW or Frame Check Word traffic is error controlled. Errors detectεd by the FCW will be correctεd by rε transmission. FCW frames may be temporally distorted. S.2.1.2.1.2.1.2. RAW RAW frames are transported without any error control. Error correction is the responsibility of the usεr. D5.2.1 .2.1 .3. Hiyh Bandwidth Signaling High Spεεd Signaling Traffic frames are usεd to carry high spεεd systεm signaling from thε MS to thε Basε. Thεsε framεs contain a FCW. Error control and rεtry are dεpεndεnt upon thε signaling sεquεncε taking placε at thε timε. D5.2.1.2.1.3.1. Low Bandwidth Bearer Low Speεd Bεarεr Traffic Framεs arε used to transport low speεd usεr traffic from thε MS to thε Basε. Tnεrε are two typεs of Bεarer traffic, FCW or error controlled traffic and RAW or error uncontrolled traffic. DSC 1.2.1.3.1.1. FCW FCW or Frame Check Word traffic is error controlled. Errors detεctεd by the FCW will be corrcctεd by re transmission. FCW frames may be temporally distorted. DSC 1.2.1.3.1.2. RAW RAW frames arε transportεd without any εrror control. Error correction is the responsibility of the usεr. D5.2. 1 .2. 1 .4. Low Bandwidth Signaling Signaling Traffic frames arε usεd to carry systεm signaling from thε MS to thε Basε. Thεsε framεs contain a FCW. Error control and rεtry arε dεpεndεπt upon t signaling sεquεncε taking placε at thε timε. DS.2.1.2.1.4.1. Symmetric Bandwidth Bearer Symmetric Bandwidth Bearεr Traffic Framεs arε usεd to transport normal usεr traffic from thε MS to thε Basε. Tnere are two types of Bearεr traffic, FCW or error controlled traffic and RAW or error uncontrolled traffic. DS.2.1.2.1.4.1.1. FCW FCW or Frame Check Word traffic is error controllεd. Errors dεtεctεd by thε FC will bε corrcctεd by rε transmission. FCW frames may be temporally distorted. DS.2.2.1.2.1.4.1.2. RA W RAW framεs arε transportεd without any εrror control. Error correction is the responsibility of the PCS servicε operator application Symmetric Bandwidth Signaling Traffic frames are usεd to carry normal systεm signaling from thε MS to thε Basε. Thεsε framεs contain a FCW. Error control and rεtry are dεpεπdent upon thε signaling sεquencε taking placε at thε time. D5.3. Slot Seizing A MS wishing to communicate with a Base must seizε at lεast onε slot on that Basε. This is accomplishεd by responding to a Basε Gεnεral Poll with a MS General Poll Response. The Genεral Poll Rεsponsε contains thε unique PID of the MS. If the Base receivεs thε General Poll Responsε for this MS thε Basε will respond at a later timε with a Spεcific Poll which contains thε PID of this MS. If thε MS sεεs such a specific poll thεn the MS may continue in the traffic mode. If thε MS doεs not see a Specific Poll containing its PID then the MS has not seized the slot and must wait a semiraπdom time based upon the MS PID and then try again in a manner similar to the backoff procedure of ANSI/IEEE 802.3. If an MS is waiting for a page from a specific Base then the MS waits for a Specific Poll from the Base. When the Basε is ready to assign a slot to the MS and initiate communications with the MS the Base will issue a Specific Poll frame containing the PID of the MS. D5.4. Multiple Associated Signaling Frames per Loop Normal slot synchronization is accomplished by timing. Both the Base and MS know which slots have been assigned for communication. The base sends its frames to the MS in the first half of the slo Tne MS synchronizes on the Base transmission to transmit its responsε. Thε timing of thε MS is sufficiently accurate that the MS can determinε which Basε transmission is dεstined for it even after having missed Base transmissions for up to oπε sεcond. During the signaling phase of a communication it is desirabiε that more than a single slot per loop be used for polling and signaling traffic. To accommodate this the Basε assigns a temporary address, thε Corrεlativε ID, to thε MS on the first Spεcific Poll. This Correlative ID is thεn carriεd in further signaling traffic from the Base to the MS. Thε MS sεarchεs for this ID in all traffic. Thε MS can then respond to any signaling traffic framε containing this Correiativε ID. Unusεd Corrεlativε ID'S arε maintainεd in a pool by thε Basε. Whεn communication has ended berwεεn thε Basε and MS thε Correlative ID is returned for reuse. Any available slot may bε usεd by thε Ba≤ε to continue signaling communications with the MS. The last slot used by the Basε for signaling traffic will bεcomε thε first slot for normal traffic usε. If the Basε returns to signaling traffic at a latεr timε thεn thε Corrεlativε ID will still bε effective and the Base may use any available slot for the control traffic. D5.5. Asymmetric Channels Traffic flow betwεen thε Basε and MS may bε εithεr symmεtric or asymmεtric. Tnε flow is controllεd by thε Basε acting upon thε Bandwidth Requεst bit in thε MS to Basε traffic hεad. Thε normal flow is symmεtric with equal traffic bandwidth being assigned in each direction. The Bandwidth Grant bits in the head of the Base to MS traffic frame establish thε actual bandwidth to be used in die spεcific slot. Tnε Base assigns slot bandwidth using the following algorithm: 1. If only the Basε requires additional bandwidth thεn the Base is granted the additional bandwidth for the next slot. 2. If only the MS requires additional bandwidth then the MS is granted the additional bandwidth for the next slot. 3. If both Base and MS or if neither request additional bandwidth then symmetric bandwidth is grantεd for the next slot. D5.6. Broadcast Channels The asymmetry of the channel may be taken to its logical extreme by granting the entire bandwidth of a slot to the Base to produce a broadcast channel. T e nature of this channel is indicated by the Bandwidth Grant bits in the traffic framε head. Multiple simultaneous Broadcast Channels can be supported. During broadcast the space normally used for the D Channel is used as a broadcast identifier. Since this occurs in thε samε position as thε Correlative Identifier the difference in usage is signaled by the Bandwidth Grant bits. D5.7. Super Frame Multiple slots in the polling loop may bε nεgotiatεd for and assignεd to an individual MS. Thε nεgotiation may takε placε at any timε via signaling traffic. Thε assignεd slots if availablε arε communicatεd by thε Basε to thε MS via thε Map Typε and Map Information Elεmεnts. Slot synchronization is maiπtaiπεd by timing for εach assignεd slot. Thε Automatic Link Transfεr procεdurε accounts for thε multiplicity of slots assignεd to thε transferring MS. A Basε must havε thε appropriate number of slots available to become a candidate as a terminal Base. The slots neεd not bε availablε in thε samε positions as thosε in thε originating Basε. D5.8. Sub Frame A MS nεεd not bε grantεd a slot in εvεry polling loop. Slot may bε granted in loops separatεd by an intεgral numbεr of intεrmεdiatε loops. Thε maximum limit on thε sεparation of slots allocatεd to a singlε MS is .5 sεconds. Session/Network Protocol Architecture E6.1. Signaling Traffic E6.1.1. Signaling Message Format F6.1.1.1. Hold Message Format F.6.1.1.1 ,1 , HLD Bas e to S Hold packets can be transmitted by either Base or the MS. They are always part of a larger signaling traffic exchange. F.6.1.1.1.2. HLD MS to Base The MS will sεπd an HLD signaling message to the Base on one of two occasions: 1. when the MS rεquirεs morε timε to procεss data and return a result to thε Base. 2. in rεsponse to an HLD message from thε Base F6.1.1.2. Synchronize Message Format Synchronize messages can be transmitted by either the Base or the MS. They are always part of recovery from an error in a signaling transaction. They are sent by whichever side discovered the error. E6...1.2.1. SYN Base to MS The Base sill send an SYN message on one of two occasions: 1. when the Base encounters an error in the current signaling transaction. 2. in response to a CT messagε from thε MS, if and only if the Base is thε initiator of thε transaction. F6.1.1.2.2. SYN MS to Base Thε MS sill sεnd an SYN mεssagε on onε of two occasions: 1. whεn thε MS εncountεrs an error in the currεnt signaling transaction. 2. in rεsponsε to a CT mεssagε from thε Basε, if and only if thε MS is thε initiator of thε transaction. E6.1.1.3. Acknowled g e Message Format Acknowledge messagεs can bε transmirtεd by εithεr thε Basε or thε MS. Thεy arε always thε last εlεmεnt of a largεr signaling exchange. Note that not every exchange ends with an ACK message. E6.1.1.3.1. ACK Base to MS F6.1.1.3.2. ACK MS to Base _ ..)■ ■ .1.4. Authentiqifinπ essa g e Form.it Authentication consists of a query message from the Base to thε MS followed by a response from the MS to the Base some timε latεr. E6, 1 , 1 ,4, 1 , AUT Ba se to MS This mεssagε is sent to thε MS from thε Basε whεnεvεr thε Basε wishεs to start an authεntication sequence. This messagε suppliεs a 64 bit numbεr that is to bε encrypted by the MS using the unique secret MS traffic key. E6.1.1.4.2. AUR MS to Base This messagε is ihε MS responsε to an authεntication rεquεst. It contains the result of εncrypting thε test numbεr supplied by the authenticatε mεssagε using thε sεcrεt uniquε MS traffic key. E6.1.1.5. Re g istration Message Format F.6.1.1.5.1. RRO MS to Base A rεgistration requεst is sent from a MS to a Basε on an initial and a pεriodic basis. Upon thε initial rεquεst thε Base enters the registration process. If the Base does not rεcεive a pεriodic registration requεst from a MS which is currently registεrεd with that Basε thεn thε Basε will initiatε a de-registration procedure F.6.1.1.5.2. RCP Base to MS Upon initial or periodic registration completion the Base responds to the MS vvith a registration completε messagε. E6.1.1.6. De-registration Message Format F6.1.1.6.1. PRO MS to Base Thε MS sεnds a dε-rεgistratioπ mεssagε to the Base when the MS wishes to dε- rεgistεr itself from the Base. If the MS does not send this message de-registration will automatically occur a fixed time-out period from the last timε thε MS sεnt a re g istration rεαuεst to thε Base. E6.1.I .7, Call Origination Message Format When a MS wishes to place an outward bound call it issues an originate mεssagε and waits for a connect rεsponsε. f.6.1.1.7.1. O^f. .VTS t as. The MS sends the call originate messagε to thε Basε to rεquεst thε placεmεnt of a outgoing call. F.6.1.1.7.2. CNC Base to MS Tnε connεct mεssagε is sεnt from thε Basε to thε MS whεn a call, either incoming or outgoing, is completεd or an outgoing call from thε MS is rejected. F6.1.1.8. Hand-off Message Format E6.1.1.8.1. NHR MS to Terminal Base The new hand-off requεst messagε is sεnt from the MS to the tεrrninal basε to initiatε thε hand-offprocεdurε. Spare 6.1.2.25 1 12 F.6.1.1.8.2. NHA Base to MS The new hand-off acknowlεdgε mεssagε is sεnt from Lhε tεrminal Basε to thε MS to acknowlεdgε thε rεcεipt of a nεw hand-off rεquεst mεssagε. F6.1.1.8.3. C C Originating Base to MS This mεssagε is sεnt from thε originating 3asε to thε MS to signal that thε nεrwork connεction is availablε at thε tεrminal Basε. E6.1 , 1.9. Call Termination Message Format E6.1 ,1 , 9,1. A NS MS to Base Tnis mεssagε is sεnt from the MS to the Base when the subscriber answers the incoming call. £_ Ji Call Release Message Format F.6.1.1.10.1 . DRI Base to MS The Base sends the drop incoming call messagε to thε MS whεn thε nεrwork drops thε call in progress. E6.1.2. Information Elements F6.1.2.1. Authentication Test Number Tne authentication test number consists of 64 bits to be encrypted by the MS. The low order bit of the 64 bit number occupies Bit 1 Octet 1 whilε the high order bit of the 64 bit number occupies Bit 8 of Octet 8. Bits Octets S 7 6 5 4 3 2 1 64 bit number to be encrypted by the MS 1 2 3 4 5 6 7 8 F.6.1.2.2. B Channel F.6.1.2.2.1. High Bandwidth Error Controlled Bearer Data High Bandwidth Error Controlled Bearεr Data issuεs will be reviewed in detail in subsequεnt submissions. F6.1.2.2.2. High Bandwidth Raw Bea rer Data High Bandwidth Raw Bearer Data issues will be reviewed in detail in subsequent submissions. E6.1.2.2.3. Low Bandwidth Frror Controlled Bearer Data Low Bandwidth Error Controlled Bearεr Data issuεs will bε reviewed in detail in subseαuεnt submissions. E6. I .2.2.4. Low Bandwidth Raw Bearer Data Low Bandwidth Raw Bεarεr Data issuεs will bε reviewed in dεtail in subsεquεnt submissions. E6.1.2.2.5. S y mmetric Bandwidth Error Controlled Bearer Data Tnε Symmεtric Bandwidth Error Controlled Bearεr Data Element consists of 160 bits of user data. The low order bit of the 160 bit numbεr rεsidεs in Bit 1 Octεt 1 whilε the high order bit of the 160 bit number resides in Bit 8 of Octet 8. Data transmitted via this mode may suffer temporal distortion but will be correctly delivered with no undetεcted lost or duplicated packets to the limits of thε FCW algorithm. Bits Octets 8 7 6 5 4 3 2 1 160 bits of bεarεr data 1 20 F6.1.2.2.6, Symmetric Baπrlwirith Raw Bearer Data The Symmεtric Bandwidth Raw Bεarεr Data Elεmεnt consists of 176 bits of usεr data. The low ordεr bit of thε 176 bit numbεr rεsidεs in Bit 1 Octεt 1 whilε thε high ordεr bit of thε 176 bit numbεr rεsidεs in Bit 8 of Octεt 22. Bits Octets 5 4 176 bits of bearεr data 11 E6.1.2.3. Base ID The Base idεntifiεr uniquely identifies the specific Base Station. Tnε low ordεr bit of thε 32 bit numbεr is locatεd in Bit 1 Octεt 1 thε high ordεr bit of thε 32 bit numbεr is locatεd in Bit 8 of Octεt 2. Bits Octets 8 7 6 5 4 3 2 1 32 bits of unique Base idεntification 2 3 4 E6.1.2.4. Broadcast ID Thε broadcast ID Information Element is used to identify specific broadcast data streams. The ID is assigned to the specific broadcast stream on a connection basis. It is thε rεsponsibility of thε broadcast application to provide periodic application broadcast heading information. Tnε broadcast ID is assigned at the start of a connection and relεased to the broadcast ID pool at the termination of the connection. Bits Octets 8 7 6 - 5 4 3 2 1 8 bits of Broadcast ID 1 f r. 1 .2.5. Ca lled Nu m ber Tnε called number consists of 80 bits of called party number. This SO bit numbεr consists of 20 IA5 characters. Bits Octεts 8 7 6 5 4 3 2 1 SObits of Called Number (IA5 characters - seε Notε) 10 Note —Thε numbεr digits appεar in multiplε octet 4's in the same ordεr in which thεy would bε εntεrεd, that is, the numbεr digit which would be cntεrεd first would bε located in thε first octεt, bits 4-8. E6.1.2.6. Connection Number The connection number specifiεs thε spεcific network connection which was allocated to carrying the bearεr channεl of this MS from thε Basε Station to the nεtwork. All bytεs of this Data Elεmεnt may not bε significant. Unused nybbles and bytεs must bε filled with "F" hex. Bits Octets 8 7 6 5 4 3 2 1 40bits of Called Number (IA5 characters - see Note) Note —The number digits appear in multiple octet 4's in the same order in which they would be entεrεd, that is, thε number digit which would be entered first would be locatεd in thε first octεt, bits 4-8. F.6.1.2.7. Correlative I) The correlativε Data Elεmεnt is usεd to temporarily identify a group of frames as being dεstinεd to a spεcific MS. Tnε ID is assignεd for thε duration of the connεction and is rεlεasεd for rεusε by anothεr MS at the termination of a connεction. Tne specific value of "FF" is reserved for broadcast usε. Tne correlation ID for a specific MS may be changed during a connεction. Bits Octεts 8 7 6 5 4 3 2 1 8 bits of corrεlativε ID F.6.1.2.8. D Channel Thε D channεl Data Elεmεnt transmits thε out of band application channεl in a byte serial manner. Thε protocol usεd on this channεl is described in document TBD. Tne data is transmitted with the low order bit of the D channεl information in Bit 1 of thε Octεt. Bits Octεts 8 7 6 5 4 3 2 1 8 bits D Channεl data E6.1.2.9. Encrypted Test Number Tne encrypted test number consists of 64 bits which have been encrypted by the MS. The low order bit of thε 64 bit numbεr occupiεs Bit 1 Octεt 1 whilε thε high ordεr bit of thε 64 bit numbεr occupiεs Bit 8 of Octεt 8. Bits Octets 5 4 3 64 bit numbεr that has been encrypted by the MS 1 i j 6 7 8 £6.1.2.10. Facility The facility Data Elemεnt describes the services being offered by the Base Station. Tnε intεmal format of this εlemεnt is TBD. Bits Octεts 8 7 6 5 4 3 2 1 32 bits of service description 1 E6, 1,2.11. _______ The frame check sequεncε Data Elεmεnt will bε a 16 bit sεquεncε. It will bε thε onεs complεmεπt of thε sum (modulo 2) of: a) Thε rεmaindεr of x k( x 15 ÷x 14 ÷x 13 ÷x 12 ÷x l l ÷x 10 ÷x 9 ÷x 8- x 7 ÷x 6 +x 5 ÷χ 4 +x 3 ÷x 2÷ l ÷ l ) dividεd (modulo 2) by thε gεnεrator polynomial x ' 6÷ x 12÷ x 5÷ 1 1 whεrε k is thε numbεr of bits in thε framε not including thε FCS. b Thε rεmaindεr of thε division (modulo 2) by thε gεnεrator polynomial xl6+χl2÷χ5÷l of thε product of x 16 by thε contεnt of the frame existing from and including the first bit of the frame to but not including the first bit of the FCS. Bits Octets 8 7 6 5 4 3 2 1 16 bits of FCS E6.1.2.12,. Guard Time 1 Guard Time issues will be rεviεwεd in dεtail in subsεquεnt submissions. £6, 1 ,2.13, Guard Time 2 Guard Timε issuεs will bε reviewed in detail in subsequεnt submissions. F6.1.2.14. Head F6.1.2.14.1. Base Pollin g Frame Head Tne head Data Elεmεnt dεscribεs thε major format of thε rest of the frame. Bits Octets B/H This bit indicates the originator of thε framε. Thε framε has bεεn sent by the MS Thε framε has bεεn sent by thε Basε Thε extension bit allows thε protocol to bε exte later date. This frame is in unextεndεd protocol This frame is in an extended protocol G/S If the ? N bit is 1 then this bit indicates that the εithεr a gεnεral or a spεcific poll. Thε framε is a spεcific poll Thε framε is a gεnεral poll P/N This bit indicatεs whεthεr the frame is a poll fra normal traffic framε. 0 This frame is a normal traffic frame 1 This frame is a polling framε Serial address bit PWR 567 Adjust MS powεr 000 001 010 011 100 101 110 111 Spare Currently unused. Reserved for future use CU This pair of bits indicate the slot utilization of this ά l 0 0 Tnε Basε is "vεry εmpty" 0 1 Tne Basε is "εmpty" 1 0 Thε Basε is "nearly full" 1 1 Tnε Basε is "full" Sparε Currently unused. Resεrvεd for futurε usε Head HCKF Cyclic Redundancy Check calculated ovεr thε 1 Check preceding bits. Generating polynomial TBD. Field F6, l ,2.14, l , Base Gεnεral Poll Hεad This Data Elεmεnt when seεn as thε hεad of a framε indicates that the frame is a Base issued genεral poll. A gεnεral poll is issuεd by thε Basε as a rεquεst for any MS to rεspond with a gεnεral poll rεsponsε if it wishεs to sεizε a slot. Bits Octεts 0 1 2 3 4 5 6 7 F6. 1 .2. 14. 1 .2. Base Specific Poll Head Tnε spεcific poll hεad indicatεs that this framε is a Basε issuεd spεcific poll. A spεcific poll rεquεsts a spεcific MS to rεspoπd. Thε slot in which the specific poll is issued has already beεn allocatεd to ihε MS and thus thε MS has sεizεd thε slot. Bits Octεts E6.1.2.14.2. Base Traffic Frame Head Bits Octets 1 2 B/H This bit indicates the originator of the frame. 0 The frame has been sent by the MS 1 The frame has been sent by the Base The extension bit allows the protocol to be extend later date. This frame is in unextended protocol This frame is in an extended protocol C N If the P/N bit is 0 then this bit indicates that the fra normal or signaling traffic. 0 Thε framε is a normal traffic. 1 The framε is signaling traffic. Thε packεt will b checked by the FCW. P/N This bit indicatεs whethεr the frame is a poll fra normal traffic frame. This frame is a normal traffic framε This framε is a polling framε SA Sεrial address bit PWR . ooo 001 010 on 100 101 1 10 BW Grant 9.1 The BW grant field grants asymmetric bandwidth Base and Mobile Station. The grant is absolute an applies to the current slot. 0 0 Symmetric bandwidth grant. Each direction has b granted one half the bandwiddi. 0 1 The maximum bandwiddi has been grantεd to thε the minimum has been granted to the Base. 1 0 The maximum bandwidth has been grantεd to thε and the minimum to the MS. 1 1 Broadcast mode the entire slot is granted to the B There is no MS frame. CU This pair of bits indicate the slot utilization of this _ 2 0 0 The Base is "very εmpty" 0 1 Tne Base is "εmpty" 1 0 Thε Basε is "nεarly full" Thε Basε is "full" Hεad HCKF Cyclic Redundancy Check calculated over the 12 Chεck preceding bits. Generating pol y nomial TBD. Fiεld E6. 1 .2, 14,2, Base Normal Traffic Head Tnis Data Elemεnt whεn sεεn as thε hεad of a framε indicatεs that thε framε is a Basε issuεd normal traffic framε. Tnε FCW of this framε is computed. Whethεr it is chεckεd or not dεpεnds upon running in εithεr thε εrror controllεd or thε raw bεarεr modε. Bits Octεts E6.1 .2. 14.2. . Base Signal I raffle Head This Data Elεmεπt whεn sεεn as thε hεad of a framε indicates that the frame is a Base issued signaling frame. Tne FCW of this frame is computed and this is chεckεd against the FCW containεd in thε framε. Bits Octets 0 1 2 3 4 5 6 7 1 E6.1.2.14.3. Mobile Station Polling Frame Head Bits Octets B/H This bit indicates the originator of the frame. 0 The frame has bεεn sent by the MS 1 Tne framε has bεεn sεnt by thε Basε Thε εxtεnsion bit allows thε protocol to be extεndε later date. 0 This frame is in unextendεd protocol 1 Tnis frame is in an extεndεd protocol 5/26094 255 as If the P/N bit is 1 then this bit indicates that the frame i either a general or a specific poll. 0 The frame is a specific poll 1 The frame is a general poll P/N This bit indicates whether the frame is a poll frame or a normal traffic frame. 0 This frame is a normal traffic frame 1 This frame is a polling frame SA This bit contains the next bit of the serial ID of the MS. This ID is the PID sεnd serially a single bit at a time. It is repeated continuously as a check against inadvertent channel capture by a MS of a different ID. BW REQ The bit indicates the bandwidth requested by the MS for the next slot assigned to the MS. 0 Minimum bandwidth is requested for the next slot. 1 Maximum bandwidth is requested for the next slot Spare Currently unused. Reserved for future use Head HC F Cyclic Redundancy Check calculated over the 12 Check preceding bits. Generating polynomial TBD. Field F.6. 1 .2.14.3.1 Mobile Station General Poll Response Head This Data Element when seen as the head of a frame indicates that the frame is a MS issued response to a general poll. It is a request to seize a slot. Bits Octets 0 1 2 3 4 5 6 7 1 F.6 1 7 14 3.2. Mobile Station Specific Poll Response Head This Data Element when seen as the head of a frame indicates that the frame is a MS issued response to a specific poll. Bits Octets 0 1 2 3 4 5 6 7 95/26094 256 E6.1.2.14.4. Mobile Station Traffic Frame Head Bits Octets B/H This bit indicates the originator of the frame. 0 Thε frame has been sent by the MS 1 The frame has been sent by the MS The extension bit allows the protocol to be extended at a later date. This frame is in unextended protocol This frame is in an extεndεd protocol S N If the S N bit is 1 then this is a signaling traffic framε. 0 The frame is normal traffic 1 The frame is signaling traffic P/N This bit indicates whether the frame is a poll frame or a normal traffic frame. This frame is a normal traffic frame This frame is a polling frame SA This bit contains the next bit of the serial ID of the MS. This ID is the PID send serially a single bit at a time. It is repeated continuously as a check against inadvertent channεl capture by a MS of a different ID. BW REQ The bit indicates the bandwidth requested by the MS for the next slot assigned to the MS. Minimum bandwidth is requested for the next slot. Maximum bandwidth is requested for the next slot Sparε Currεntly unusεd. Rεsεrvεd for future usε Hεad HCKF Cyclic Redundancy Check calculated over thε 1 Chεck prεcεding bits. Gεnεrating polynomial TBD. Field F6. 1 .2. 14.4.1 . Mobilε Station Normal Traffic Hεad Thε mobilε station normal traffic hεad Data Element indicates that this frame is a normal traffic responsε to thε basε. The framε chεck field of this frame will be calculated by the Base. It will be checkεd if thε MS is in the error controlled bearεr modε. Bits Octεts 0 1 2 3 4 5 6 7 Tnis Data Elεmεnt whεn sεεn as thε head of a frame indicatεs that thε framε is a MS issuεd signaling frame. The FCW of this frame is computed and this is checked against the FCW contained in the frame. Bits Octets E6, 1 ,2.15- Map Map Data issues will be reviewed in detail in subsequent submissions. £6,1.2.16,, Map Type The Map Type Data Elemεnt idεntifiεs thε typε of map to follow. Bits Octεts 6 5 4 3 2 1 8 bits of map type 1 The messagε typε Data Elεmεnt dεfinεs thε format of thε rεst of thε framε. It also acts as an operation code to thε dεstination unit εithεr Basε or MS. Bits Octεts The nεw connection number specifies the specific network connection which has beεn allocated to carrying the bearer channel of this MS from the new terminating Base Station in a hand-off sequεncε to thε nεrwork. All bytes of this Data Elemεnt may not be significant. Unusεd nybblεs and bytes must be filled with "F" hex. Bits Octεts Notε —The numbεr digits appεar in multiplε octet 4's in thε same order in which they would be entεrεd, that is, thε numbεr digit which would be εntεred first would bε locatεd in thε first octεt 4. £6, 1 ,2, 19, Old Connection Num ber ' Tnε old connection numbεr specifies the specific network connection which was allocated to carrying the bearer channel of this MS from the old originating Base Station a hand-off sεquεncε to thε nεtwork. All bytεs of this Data Elεmεnt may not bε significant. Unusεd nybblεs and bytεs must bε filled with "F" hex. Bits Octets 40bits of Connection Number (I.A5 characters - see Note) Notε —The number digits appεar in multiple octet 4's in the same order in which they would be entered, that is, the number digit which would be entered first would bε located in the first octεt 4. E6, 1 ,2-20, £££. Thε PCP, Powεr Control Pulsε, is a short sεquεncε usεd to allow the Basε to find thε appropriatε divεrsity εlεmεnt to usε in transmitting to thε MS and to access the powεr lεvεl of thε MS for furthεr adjustmεnt. TBD. i . 6- 1-2.21. an This Information Elεmεnt is thε pεrsonal identification number assigned to this MS. It absolutely and uniquely idεntifiεs thε MS. This numbεr is 40 bits long. Th: low ordεr bit of thε 40 bit πumbεr rεsidεs in Bit 1 of Octεt 1 whilε thε high ordεr bit of thε 40 bit numbεr rεsidεs in Bit 8 of Octεt 5. Bits Octets 5 4 40bits of uniαuε MS idεntification number E&JL . . 7 Result Thε intεrprεtation of thε rεsult Information Elεmεnt is dεpεndent upon thε typε of mεssagε in which it is found. Gεnεrally it may be intεrprεtεd as thε rεsult of thε εxεcution of thε previous signaling traffic for this MS. Bits Octets 8 7 6 . 5 4 3 2 1 Rεsult RCP Message Result Bits 1 -8 Interpretation 00 This MS is now rεgistεrεd to this Base unit. 01 This Base unit will not accεpt this MS for rεgis CNC Message Result Bits 1 Interpretation 00 The requεstεd call has bεεn connεctεd. 01 Unablε to complεtε thε rεαuεstεd call. £6,1.2,23, Service Provider This 16 bit Information Elεmεnt whεn prεsεnt in a Basε to MS signaling mεssagε idεntifiεs thε PCS sεrvicε providεr that opεratεs thε Base Station. When prεsεnt in a MS to Basε signaling mεssagε it spεcifics thε idεntification of thε PCS sεrvicε providεr that thε MS wishεs to usε. Thε low order bit of this 16 bit elemεnt resides in Bit 1 of Octet 1 while the high ordεr bit of this 16 bit element resides in Bit 8 of Octet 2. Bits Octets 8 7 6 5 4 3 2 1 16 bits of unique Servicε Providεr Idεntification numbεr E6.1.2-24, Service Request This 16 bit Information Element specifies the type of servicε being requested by the MS. Bits Octets 7 5 4 3 16 bits of MS Servicε Rεquεst Dεscription EvM .2,25, .Spare Thε Sparε Information Elεmεnt rεprεsεnts unusεd spacε. All sparε spacε must bε εvεnly divisiblε into Octεts. All unusεd spacε is rεsεrvεd for futurε use. E.6- 1 -2.26.. UPT2 Tnis 40 bit Information Elemεnt is thε Univεrsal Personal Telecommunications numbεr that has bεεn grantεd to the subscribεr operating the MS. This 40 bit number consists of 10 IA5 characters. Bits Octets 8 5 4 40bits of Universal Personal Telecommunications Number (IA5 characters - sεε Notε) Notε —Thε πumbεr digits appεar in multiplε octet 4's in the same order in which they would be entεrεd, that is, thε numbεr digit which would bε επtεrεd first would bε locatεd in thε first octεt 4. £6.1.2-27, one This 16 bit Information Elεmεnt idεntifiεs the paging zone of thε specific Base Station. If a MS moves from a Basε Station in onε zonε to aπothεr Basε Station in thε samε zonε immεdiate rεgistration is not rεquirεd. Bits Octets 1 i E6.2. Bearer Traffic E6.2.1. Voice £6.2.1 , 1, 32 KBPS 32 kbps Bearer Traffic issues will be reviewed in detail in subsequent submissions. E6.2.1.2. 8 KBPS 8 kbps Bearer Traffic issues will be reviewed in detail in subsequent submissions. £6.2- 1 ,3. 4 KBPS 4 kbps Bearer Traffic issues will be reviewed in detail in subsequent submissions. E6.2.2. Data Data Bearer Traffic issues will be reviewed in detail in subsequent submissions. E6.3. Multiple Mode Traffic A single MS may ' have multiple connections established through the Base Station to the network via multiple slots. One slot may, for examplε, bε assigned to audio traffic whilε othεr slots arε dεvotεd to data traffic. Alternative Embodiments While preferred embodiments are disclosed herein, many variations are possible which remain within the concept and scope of the invention, and these variations would become clear to one of ordinary skill in the art after perusal of the specification, drawings and claims herein. For example, information which is transmitted from transmitter to receiver is referred to herein as "data", but it would be clear to those of ordinary skill in the art, after perusal of this application, that these data could comprise data, voice (encoded digitally or otherwise) error-correcting codes, control information, or other signals, and that this would be within the scope and spirit of the invention. Moreover, while the specification has been described with reference to TDMA multiplexing of air channels, it would be clear to those of ordinary skill in the art, after perusal of this application, that air channels may be multiplexed by other means, including FDMA (frequency division multiplexing) , by assigning air channels to differing frequency bands, CDMA (code division multiplexing) , by assigning air channels to differing spread-spectrum spreading codes, other multiplexing techniques, or combinations of these multiplexing techniques, and that this would be within the scope and spirit of the invention.

Claims: CLAIMS What is claimed is: 1. In a communication system having a base station and a plurality of user stations, a method of establishing communication between said base station and one of said plurality" of user stations, comprising the steps of transmitting a general polling message from said base station; receiving said general polling message at said one user station; transmitting a general polling response from said user station; receiving said general polling response at said base station; transmitting a specific polling message from said base station; receiving said specific polling message at said one user station; transmitting a specific polling response from said one user station; receiving said specific polling response at said base station; and thereafter transmitting and receiving information messages between said base station and said one user station over an established communication link. 2. A method as in claim 1, comprising the steps of detecting a measure of quality of said communication link between said base station and said one user station; transmitting a specific polling message from said base station in response to said measure of quality; receiving said specific polling message at said one user station; transmitting a specific polling response from said one user station in response to said specific polling message; receiving said specific polling response at said base station; and thereafter transmitting and receiving further information messages between said base station and said one user station over a re-established communication link. 3. A method as in claim 1, comprising the steps of repeatedly transmitting an identifier for said one user station with information messages on said communication link; receiving said identifier with information messages on said communication link; comparing said identifier at said one user station with a local identifier for said one user station; and awaiting receipt of said specific polling message in response to a result of said step of comparing. 4. A method as in claim 1, comprising the steps of transmitting a general polling message from a second base station, said general polling message comprising a field for transmitting a first set of network information; receiving said general polling message at said one user station; transmitting a specific polling message from said second base station; receiving said specific polling message at said one user station, said specific polling message comprising a field for transmitting a second set of network information; recording said first and second set of network information at said one user station; establishing a communication link between said second base station and said one user station in response to said network information. 5. A method as in claim 4, comprising the steps of transmitting said information about said one base station from said user station to said second base station. 6. A method as in claim 1, comprising the steps of transmitting a request to initiate a telephone call from said one user station; receiving said request at said base station; and initiating a telephone call from said base station in a telephone network. 7. A method as in claim 1, wherein said general polling response comprises an identifier for said one user station, said specific polling message comprises said identifier, and said specific polling response comprises said identifier. 8. In a communication system having a base station and a plurality of user stations, a method of establishing communication between said base station and one of said plurality of user stations, comprising the steps of receiving a request at said base station from a telephone network to complete a telephone call to said one user station; transmitting a specific polling message from said base station; receiving said specific polling message at said one user station; transmitting a specific polling response from said one user station; receiving said specific polling response at said base station; and thereafter transmitting and receiving information messages between said base station and said one user station over an established communication link. 9. In a communication system having a plurality of base stations and a plurality of user stations, a method of establishing communication between one of said plurality of base stations and one of said plurality of user stations, comprising the steps of establishing communication between a first one of said plurality of base stations and one of said plurality of user stations; receiving network information at said one user station from a second one of said plurality of base stations; breaking communication between said first base station and said one user station, under control of said user station; establishing communication between said second base station and said one user station, under control of said user station.

Inventors: ANDERSON GARY B, JENSEN RYAN N, PETCH BRYAN K, PETERSON PETER O, ANDERSON, GARY, B., JENSEN, RYAN, N., PETCH, BRYAN, K., PETERSON, PETER, O.
Applicants: OMNIPOINT CORP, OMNIPOINT CORPORATION
Application year: 1995
Main classification: H04M11
IPC codes: G10L19, H04B7, H04J3, H04J13, H04L1, H04L12, H04W52, H04W74