System, apparatus, computer program product and method for controlling terminal output power

Controlling the output power level of a dual transfer mode (DTM) capable terminal involves generating a network message. The network message may be a circuit-switched (CS) handover command and/or a point-to-point signaling message. A maximum output power level value is associated with the network message. The network message is transferred from the network to the terminal. A packet-switched (PS) output power level of the terminal is determined using the maximum output power level value received via the network message.

FIELD OF THE INVENTION

This invention relates in general to wireless communications, and more particularly to a system, apparatus, computer program product, and method for controlling terminal output power levels.

BACKGROUND OF THE INVENTION

In wireless network environments such as cellular networks, network entities are provided to facilitate the communication between communicating devices on the network. In Global System for Mobile communications (GSM) networks, Base Station Systems (BSS) are provided on the network, which include one or more Base Transceiver Stations (BTS) and a Base Station Controller (BSC). The BTS manages the radio interface to Mobile Stations (MS) and/or other terminals, and includes the transceivers and antennas to service each cell. A group of BTSs are controlled by a BSC, which provides the control functions and physical links between the Mobile Switching Center (MSC) and the BTS.

The interface between the network and a mobile terminal is often referred to as the radio interface. Radio Resource management (RR) and/or MSC procedures are used to establish, maintain, and release connections that allow a point-to-point dialogue between the network and the terminal. These procedures include “handover” procedures, which generally refers to the passing of a call in progress from one channel or cell to another. An RR element such as the BSC performs high-capacity switching functions, including handover, as well as control of radio frequency (RF) power levels in BTSs.

The first GSM and other analogous networks were designed for voice services. When the user of the GSM data services began, it became evident that the circuit-switched (CS) bearer services were not particularly well suited for certain types of applications, such as those involving date transmissions exhibiting a “bursty” nature. Therefore, in the GSM context, the new packet-switched (PS) data transmission service, General Packet Radio Service (GPRS), was defined for packet services. Generally, GPRS is a packet radio network utilizing the GSM network, which endeavors to optimize data packet transmission by means of GPRS protocol layers on the air interface between a mobile station (or other terminal) and a GPRS network.

If there is no active connection between a terminal and a BSS, the terminal is at rest or in “idle” mode, and the BSS has no specific tasks to perform relative to the terminal. However, the terminal continues to monitor control channels such as the Broadcast Control Channel (BCCH) or the Packet Broadcast Control Channel (PBCCH) of the current and neighboring cells, to facilitate location update operations. In dedicated mode, a physical point-to-point bidirectional RR connection is established. Thus, in dedicated mode, the terminal is allocated dedicated channels for communicating information.

A GPRS mobile station (MS) or other GPRS terminal can operate in one of three modes of operation. A “Class A” mode of operation refers to a mode where the terminal is attached to both GPRS and other GSM services. The mobile user can initiate and/or receive calls on the two services simultaneously. For example, the mobile user can participate in a GSM voice call while simultaneously receiving GPRS data packets. A “Class B” mode of operation refers to a mode where the terminal is attached to both GPRS and other GSM services, but the terminal can only operate one set of services at a time. Another mode of operation, “Class C,” refers to a mode where the terminal can only be attached to either the GSM network or the GPRS network. The selection is performed manually, and there are no simultaneous operations.

Terminals operating in the Class A mode of operation therefore can be attached to both CS and PS services, and can be actively engaged in both services simultaneously. An example of such a Class A mode of operation is the Dual Transfer Mode (DTM) used in GSM/GPRS systems. Other network environments may include analogous modes of operation, such as the Multi Radio Access Bearer (Multi RAB) mode in Wideband Code Division Multiple Access (WCDMA) systems. For example, DTM is applicable for terminals that support GPRS/EGPRS or future analogous systems. A terminal in DTM has resources for an RR connection and is simultaneously allocated resources for one or more temporary block flows (TBFs), provided that the BSS coordinates its allocation of radio resources.

It is noted that during a connection, i.e. when the terminal is in transfer mode such as the “dedicated mode,” power control functions serve to maintain and optimize the radio channel. It is very important that terminals that send data to the network use the proper output power level. If the output power level of the terminal is too low, data throughput may suffer due to errors caused by sub-optimal radio conditions. If the output power level of the terminal is too high, excessive power consumption results, and the data transmission may cause interference to other channels used by other terminals.

As indicated above, the terminal's maximum output power is based on parameters received in system information messages via PBCCH/BCCH while in the (packet) idle mode. When the terminal moves via the dedicated mode to the dual transfer mode the maximum output power may be correct. However when the terminal is in dual transfer mode and it is handed over to a new cell, the terminal is lacking the correct output power parameters of the new cell. The same problem exists if the terminal is in the dedicated mode and it is handed over one or several times to a new cell in which the terminal requests PS resources. The terminal cannot calculate correct output power level for packet switched resources in the new cell while staying in the dedicated mode. Therefore the terminal is not aware of the correct output power and specifically the correct maximum output power for packet transfer when it enters to the dual transfer mode in the target cell.

Accordingly, there is a need in the communications industry for a manner of properly establishing the terminal output power levels in changing circumstances, such as where a terminal is operating in dual transfer mode and a handover occurs. A further need exists for a system and methodology that provides an unintrusive and efficient manner for providing such information, while working within existing protocols and structures. The present invention fulfills these and other needs, and offers other advantages over the prior art.

SUMMARY OF THE INVENTION

To overcome limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a system, apparatus, computer program product and method for controlling terminal output power levels.

The invention facilitates reaching a known and/or consistent PS output power control for DTM in all cases, including DTM after a CS handover. The PS power control formula includes the PMAX parameter, which defines the maximum power allowed for PS channels. Because this parameter is currently not available in all cases, one embodiment of the invention involves providing the PMAX parameter value for the MS or other terminal through the CS handover command message from which the Power Level parameter value is used for PMAX, when PMAX is not otherwise available. In another embodiment of the invention, the PMAX parameter is added to system information messages, mainly system information6and DTM information message. This allows the MS to be aware of the PMAX parameter value always before requesting DTM. Yet another exemplary embodiment of the invention involves defining a default value for the PMAX parameter. This default value can be used whenever the PMAX value is not otherwise provided.

In one embodiment of the invention, a method for controlling the output power level of over-the-air (OTA) transmission signals from a terminal operable on a network involves providing a power level parameter to the terminal via a circuit-switched (CS) handover command. The power level parameter is utilized for packet-switched (PS) power control for PS traffic after CS handover.

In more particular embodiments, the method also involves defining a PS output power level to be used as the terminal's output power level for PS traffic after CS handover using the power level parameter received via the CS handover command. The PS output power level may be defined using a default value in defining the PS output power level if the power level parameter is not provided via the CS handover command.

In another more particular embodiment of the invention, the power level parameter includes a maximum power level parameter. Providing the maximum power level parameter to the terminal via the CS handover command may involve placing the maximum power level parameter in an existing power level information element of the CS handover command. The method may also involve defining a maximum packet-switched output power level (PMAX) and a PS output power level based on the maximum power level parameter received via the CS handover command. The PS output power level may be used as the terminal's output power level for PS traffic after CS handover. The PS output power level may be determined calculating the PS output power level according to the formula PCH=min(Γ0−ΓCH−α*(C+48), PMAX). In one configuration, the terminal may simultaneously maintain a CS data session and a PS data session via the network.

In another embodiment of the present invention, a method for controlling the output power level of OTA transmission signals from a terminal operable in dual transfer mode (DTM) on a network involves generating at least one signaling message at the network. A power level parameter is associated with the signaling message. The signaling message is transmitted from the network to the terminal. A PS output power level is defined using the power level parameter received via the at least one signaling message. The PS output power is to be used as the terminal's output power level for PS traffic.

In more particular embodiments of the invention, the signaling message may determine whether or not DTM is supported in the new cell. The signaling message may also include a point-to-point system information message, a system information6(SI6) message, and/or a DTM information message. In one configuration, the PS output power may to be used as the terminal's output power level for PS traffic after a circuit-switched CS handover. Transmitting the signaling message may involve transmitting the at least one signaling message via a slow associated control channel (SACCH).

In another embodiment of the invention, a terminal is provided that is capable of communicating OTA via a CS network and a PS network. The terminal includes a transceiver capable of receiving a maximum power level parameter via at least one of a CS handover command and a point-to-point signaling message. A processor of the terminal is configured to utilize the power level parameter for PS power control for PS network traffic after a CS network handover.

In another embodiment of the invention, a processing arrangement is capable of communicating with a terminal via a CS network and a PS network. The arrangement includes a processor configured to determine a maximum power level parameter usable by the terminal for PS power control for PS network traffic after a CS network handover. The arrangement also includes a transceiver capable of sending the maximum power level parameter to the terminal via at least one of a CS handover command and a point-to-point signaling message.

In another embodiment of the invention, a computer-readable medium has instructions stored thereon. The instructions are executable by a computer system for controlling the output power level at a terminal by performing steps that involve receiving a maximum power level parameter via a network from at least one of a CS handover command and a signaling message. A PS output power level is determined based on the maximum power level parameter. A PS data session is established using the PS output power level after a CS handover.

In another embodiment of the invention, a system for controlling the output power level of OTA transmission signals from a terminal operable on a network includes 1) means for generating network message that includes at least one of a CS handover command and a signaling message; 2) means for associating a maximum output power level value with the network message; 3) means for transmitting the network message from the network to the terminal; and 4) means for defining a PS output power level of the terminal using the maximum output power level value received via the network message.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Generally, the present invention provides a system, apparatus, computer program product, and method for controlling terminal output power levels. The present invention is applicable in network environments that support simultaneous support of multiple services, such as the simultaneous support of circuit-switched (CS) voice and packet-switched (PS) data services. For example, in WCDMA systems this is generally referred to as Multi Radio Access Bearer (Multi RAB) services, and in GSM/GPRS systems it is generally referred to as Dual Transfer Mode (DTM). While the present invention is applicable in these and other analogous network environments, the present invention is described in terms of GSM/GPRS networks supporting DTM. GSM/GPRS networks are described generally below in order to provide a representative context in which embodiments of the present invention may be implemented. The invention is equally applicable for Enhanced GPRS (EGPRS), GSM/EDGE Radio Access Networks (GERAN), and other analogous network environments including CS and PS services.

FIG. 1illustrates some general aspects of a GSM/GPRS network environment100in which the principles of the present invention may be utilized. Global System for Mobile communications (GSM) is a digital cellular communications system serving as a Public Land Mobile Network (PLMN), where multiple providers may set up mobile networks following the GSM standard. GSM is capable of providing both voice and data services. A GSM (or analogous) network100typically includes components such as terminals or Mobile Stations (MS)102, Base Transceiver Stations (BTS)104, Mobile Switching Center (MSC)106, etc. A GSM network may be viewed as a collection of various subsystems, including the Radio Subsystem (RSS) which covers radio aspects, Network and Switching Subsystem (NSS) which manages functions such as call forwarding, handover and switching, and the Operation Subsystem (OSS) that manages the network. Various aspects of the RSS are described in greater detail below.

One or more terminals102communicate with the BTS104via an air interface. The BTS104is a component of a wireless network access infrastructure that terminates the air interface over which subscriber traffic is communicated to and from the terminal102. The Base Station Controller (BSC)108is a switching module that provides, among other things, handover functions, and controls power levels in each BTS104of the Base Station System (BSS)110. The BSC108controls the interface between the MSC106and BTS104in a GSM mobile wireless network, and thus controls one or more BTSs in the call set-up functions, signaling, and in the use of radio channels.

A General Packet Radio System (GPRS) mobile communications network112is a packet-switched service for GSM that mirrors the Internet model and enables seamless transition towards 3G (third generation) networks. GPRS thus provides actual packet radio access for mobile GSM and time-division multiple access (TDMA) users, and is ideal for Wireless Application Protocol (WAP) services. The BSC108also controls the interface between the Serving GPRS Support Node (SGSN)114and the BTS104in a GPRS network112. Other BTS, BSC, and SGSN components may also be associated with the network system, as depicted by BTS116and BSC118of BSS120, and SGSN122.

The MSC module106generally includes or is otherwise associated with the MSC, Visiting Location Register (VLR)124, and Home Location Register (HLR)126. The MSC106performs a variety of functions, including providing telephony switching services and controlling calls between telephone and data systems, switching voice traffic from the wireless network to the landline network if the call is a mobile-to-landline call, or alternatively switching to another MSC if the call is a mobile-to-mobile call. The MSC106also provides the mobility functions for the network, and serves as the hub for multiple BTSs. Generally, it is the MSC106that provides mobility management for subscribers, in order to register subscribers, and authenticate and authorize services and access for subscribers. In GSM systems, some of the functionality of the MSC106may be distributed to the BSC108, while in other systems such as TDMA systems, the BSC108functions are often integrated with the MSC106.

Associated with the MSC106is the HLR126and VLR124. The HLR126is a database that stores information about subscribers in the mobile network, and is maintained by one or more service providers for their respective subscribers. The MSC106uses the information stored in the HLR126to authenticate and register the subscriber by storing permanent subscriber information including the service profile, the current location of terminals, and activity status of the mobile user. The VLR124is a database that may be maintained by the MSC106to keep track of all the visiting terminals within a mobile telephony system.

The Serving GPRS Support Nodes (SGSN)114,122serve terminals that support GPRS by sending or receiving packets via a respective BSS110,120, and more particularly via the BSC108,118in the context of GSM systems. The SGSN is responsible for the delivery of data packets to and from the terminals within its service area, and performs packet routing and transfer, mobility management, logical link management, authentication, charging functions, etc. In the exemplary GPRS embodiment shown inFIG. 1, the location register of the SGSN114stores location information such as the current cell and VLR associated with the terminal102, as well as user profiles such as the International Mobile Subscriber Identity Number (IMSI) of all GPRS users registered with this SGSN. Another network element introduced in the GPRS context is the Gateway GPRS Support Node (GGSN)128, which acts as a gateway between the GPRS network112and a packet switched public data network, such as data network130. This gateway128allows mobile subscribers to access the public data network130or specified private IP networks. The connection between the GGSN128and the public data network is generally enabled through a standard protocol, such as the Internet Protocol (IP).

As previously indicated, the RSS includes components such as terminals, and the BSS which in turn generally includes a plurality of BTSs and a BSC. The BTS includes radio components such as a transceiver and antenna, while the BSC effects switching between BTSs, manages network resources, etc. The RSS supports a certain number of logical channels that fall within two primary categories including the traffic channels (TCH) and the control channels (CCH). The TCHs are intended to carry data such as encoded speech or user data in circuit switched mode, while Packet Data TCHs (PDTCH) are intended to carry user data in packet switched mode. Multiple full rate channels and multiple packet data TCHs can be allocated to the same terminal, which is referred to as multislot configurations and multislot packet configurations respectively. Control channels carry signaling and/or synchronization data. There are various primary control channel categories in GSM systems, including broadcast, common, dedicated, and CTS control channels. The broadcast channels include Frequency Correction Channels (FCCH), Synchronization Channels (SCH), a Broadcast Control Channel (BCCH) as well as Packet BCCH (PBCCH) channels.

The interface between the network and a mobile terminal is often referred to as the radio interface. Radio Resource management (RR) and/or MSC procedures are used to establish, maintain, and release connections that allow a point-to-point dialogue between the network and the terminal. These procedures include “handover” procedures. Handover generally refers to the passing of a call in progress from one channel or cell to another. For example, inter-cell handover refers to the passing of a call from one cell coverage area to another. This typically occurs where the terminal is moving such that it is proximate the border of the cell area, and signal measurements indicate that a transfer of the call to the bordering cell is required or otherwise desirable to ensure proper radio signal quality. Intra-cell handover generally refers to a handover from one channel/timeslot configuration in the serving cell to another channel/timeslot configuration in the same cell. Such a handover may be performed to address interference issues, reduce network congestion, or the like.

Various link control functions are performed between the terminal and its associated BSS, including functions such as handover control, measurement collection and processing, and transmitter power control. Regarding power control issues, it is important that terminals that are sending data to the network use the correct power level. If the terminal power levels are too low, data throughput may suffer due to increased errors resulting from these poor radio conditions. If the terminal power levels are too high, power consumption is not optimal, and other problems such as transmission interference to other channels used by other terminals can occur.

To address these issues, the terminal and the network communicate information relating to the power levels to be used by the terminal. This is generally referred to as adaptive control of the radio frequency (RF) transmit or output power. In GPRS networks, the terminal calculates the correct output power levels based on formulas. Such formulas may include sets of parameters of which the terminal is to obtain from various sources, such as system information messages broadcasted by the network, or from control messages that are sent specifically to each of the terminals. The broadcasted system information messages are currently transmitted by the network in two possible logical channel structures, depending on the base selected by the network operator. For example, if a packet channel structure exists, the system information messages are transmitted by the network on the PBCCH, which is a downlink signal (i.e. from network to terminal) used to broadcast cell-specific information. If a packet channel structure does not exist, the system information messages are broadcasted by the network on the BCCH, which is also a downlink signal used to broadcast cell-specific information.

Based at least in part on the information received by the terminal from the network, the terminal can calculate the output power to which it will transmit data on each individual uplink packet data channel (PDCH). For example, one current formula by which the terminal can calculate its output power is provided in the 3rdGeneration Partnership Project (3GPP) technical specification 3GPP TS 45.008, V6.6.0, February 2004, entitled “Technical Specification Group GSM/EDGE Radio Access Network; Radio subsystem link control (Release 6) (hereinafter referred to as “TS 45.008”), the content of which is incorporated by reference in its entirety. An output power formula provided by TS 45.008 is shown in Equation 1 below:
PCH=min(Γ0−ΓCH−α*(C+48),PMAX)  Equation 1
In Equation 1, PCHrepresents the RF output power, and the formula provides a manner in which the terminal can calculate a substantially minimal RF output power while maintaining the quality of the radio links. The channel RF output power, PCH, thus represents the minimum of 1) the maximum allowed output power in the cell (PMAX); and 2) the calculation of Γ0−ΓCH−α*(C+48). These values/variables are described below:ΓCHis an MS and channel specific power control parameter, sent to the MS in a Radio Link Control (RLC) control message (see 3GPP TS 44.060). For those uplink Packet Data Channels (PDCHs) for which ΓCHhas not been defined, the value 0 is used;Γ0=39 dBm for GSM 400, GSM 700, GSM 850 and GSM 900=36 dBm for DCS1 800 and PCS 1900;α is a system parameter, broadcast on PBCCH or optionally sent to the MS in an RLC control message (see 3GPP TS 44.018 and 3GPP TS 44.060);C is the normalized received signal level at the MS as defined in TS 45.008, §10.2.3.1; andPMAX is the maximum allowed output power in the cell, and equals:a) GPRS_MS_TXPWR_MAX_CCH if PBCCH or CPBCCH exist; orb) MS_TXPWR_MAX_CCH otherwise
As can be seen from Equation 1, PMAX represents a key component of the formula, as the result of the calculation of Γ0−ΓCH−α*(C+48) is irrelevant if it is not lower than PMAX.

As previously indicated, PMAX is received in system information messages. For example, when received via the BCCH, information elements including RR information elements may provide the PMAX. One such information element is defined in 3GPP TS 44.018, V6.6.0, February 2004, entitled “Technical Specification Group GSM/EDGE Radio Access Network; Mobile radio interface layer 3 specification; Radio Resource Control (RRC) protocol (Release 6) (hereinafter referred to as “TS 44.018”), the content of which is incorporated by reference in its entirety. This information element is the “cell selection parameters” information element which provides a variety of information about a cell, including the maximum allowed output power in the cell (e.g., PMAX). In accordance with TS 44.018, the PMAX value of the cell selection parameters information element is coded as shown in Table 1 below:

TABLE 187654321octet 1MS_TXPWR_MAX_CCHoctet 2octet 3
The PMAX value is provided in the 5-bit field MS_TXPWR_MAX_CCH of octet2, and is coded as the binary representation of the power control level corresponding to the maximum transmission power level a terminal may use when accessing on a Control Channel (CCH) and/or Traffic Channel (TCH). MS_TXPWR_MAX_CCH is thus broadcasted on the BCCH of the cell. A similar 5-bit field, GPRS_MS_TXPWR_MAX_CCH, is broadcasted on PBCCH or Compact PBCCH (CPBCCH) of the serving cell where such channel is provided by the network (see 3GPP TS 44.060). The particular value MS_TXPWR_MAX_CCH or GPRS_MS_TXPWR_MAX_CCH, having a range of 0-31, is then used by the terminal for defining PMAX when calculating the RF output power PCHas shown in Equation 1 above.

According to TS 44.018, the cell selection parameters information element is included in system information messages which are sent to the terminal. More particularly, the cell selection parameters information element (and consequently the MS_TXPWR_MAX_CCH value) is provided in system information types 3 and 4. System information types 3 and 4 are messages sent on the BCCH by the network. In this manner, the terminal can receive the value to be used as PMAX in the calculation of the appropriate RF output power.

Analogously, the value for PMAX may be received via other channels, such as the PBCCH where packet channel structure exists. For example, in the GPRS context, the PBCCH is a unidirectional point-to-multi-point signaling channel from the network to the terminals, and is used to broadcast information to terminals relating to the GPRS radio network organization. In addition to GPRS-specific information, the PBCCH may also broadcast system information about circuit switched services so that a GSM/GPRS terminal does not need to also listen to the BCCH. Packet system information, including a value for PMAX, is provided via the PBCCH in a manner analogous to that described for the BCCH. For example, a packet system information type 3 message is sent by the network on the PBCCH or Packet Associated Control Channel (PACCH) giving information of the BCCH allocation in the neighbor cells and cell selection parameters for serving cell and non-serving cells, where the cell selection parameters include the GPRS_MS_TXPWR_MAX_CCH field.

It can be seen that a primary factor in calculating the channel RF output power, PCH, is PMAX, since the calculation for terminal output power uses the lowest of PMAX or Γ0−ΓCH−α*(C+48). However, in some cases, the terminal does not know this maximum output power parameter for packet transmission. For example, when the terminal operation moves from the dedicated mode to the dual transfer mode (DTM), the maximum output power is correct. On the other hand, when the terminal is in the DTM and experiences a handover to a new cell, the terminal is lacking the correct output power parameters of the new cell. A similar problem exists if the terminal is in the dedicated mode and is handed over one or more times to a new cell in which the terminal requests packet-switched resources. The terminal cannot calculate the correct output power level for PS resources in the new cell while staying in the dedicated mode. Therefore, the terminal is not aware of the correct output power, and specifically the correct maximum output power for packet transfer, when it enters the DTM in the target cell. The present invention addresses these and other shortcomings of the prior art.

A typical signaling scenario associated with a DTM handover is first described.FIG. 2illustrates such a typical signaling scenario. In the illustrated embodiment, the mobile station (MS)200represents the terminal. The example further includes network elements including the Base Station System (BSS)202(which may include one or more BTSs and a BSC), an MSC204, and an SGSN206. MS200is assumed to have DTM capabilities and is thus can operate in a Class A mode of operation. A Class A mode of operation refers to a mode where the terminal is attached to both GPRS and other GSM services. The terminal user can make and/or receive calls on the two services simultaneously, such as engaging in a normal GSM voice call and receiving GPRS data packets at the same time. Both resources (CS and PS) are allocated in the same frequency band either in one timeslot (i.e. single timeslot allocation) or in adjacent timeslots (i.e. multislot allocation). In addition, when the terminal is in dedicated mode, it cannot monitor its BCCH/PBCCH. All required system information (while in dedicated mode) is provided via SACCH with SI5or SI6.

One group of procedures includes those related to the change of the serving cell when the MS200is in DTM, namely “handover.” Referring toFIG. 2, a PS session210A may be in progress, which operates between the MS200and the SGSN206and involves the BSS202and MSC204. As indicated in connection withFIG. 1, an SGSN206serves terminals that support GPRS by sending or receiving packets via a respective BSS202, and more particularly via the BSC (seeFIG. 1) in the context of GSM systems. Further, because DTM and other Class A modes of operation allow simultaneous resource allocation, a CS session212A (e.g., voice call) may also be in progress. If the MS200simultaneously has both connections210A,212A in progress (e.g., PS and CS connections), then the MS200is in dual transfer mode, which is assumed for purposes of the present example.

When a handover is to occur, the CS connection is handed over, and packet resources are released. More particularly, a handover command214message is sent from the network, particularly from the BSS202, to the MS200. The handover command214message describes the CS resources in the target cell. A handover command214is a message that may be sent on the main DCCH by the network to the terminal to change the dedicated channel configuration. Table 1 below illustrates an exemplary handover command, as set forth in TS 44.018:

FIG. 3illustrates various representative manners of providing the power level parameter to the terminal for PS power control for DTM after CS handover. A first embodiment provides the power level parameter300A in a handover command302from the BSS304to the terminal306. The terminal may include any terminal/mobile station, such as a mobile phone306A, personal digital assistant (PDA)306B, computing device306C, or other terminal306D. The power level parameter300A represents the maximum output power level for PS traffic after CS handover. The handover command302is provided from the BSS to the terminal, as was also illustrated inFIG. 2where a handover command214is illustrated as being sent from the BSS202to the MS200.

Currently the value of the power level parameter is used as initial output power level at the new cell after CS handover. The parameter is valid until power control starts either on a TCH, FACCH, SACCH, PDTCH or SDCCH, e.g., until a new power control command is received on the SACCH channel. The terminal shall employ the most recently commanded power control level appropriate to each above mentioned channel for all transmitted bursts.

Based on the existing power control handling, it is possible for the network to set the power level parameter (the initial CS output power for the new cell) to a level that is suitable to replace the PMAX parameter for PS power control on the new cell.

When CS signaling starts, the network commands the terminal to use a lower power level for the CS connection if feasible, based on radio conditions. In the DTM case, the value of the power level parameter is used as a PMAX value when calculating the terminal (PS) output power as specified in TS 45.008. It is noted that the invention makes it possible to set the maximum output power for packet transfer after DTM handover without any signaling changes.

In an embodiment using the handover command, the invention makes use of an existing “power level” parameter field in the handover command. As was shown in Table 1 above, the handover command includes an information element (IE) referred to as the “Power Command and Access type.” This IE may be coded as shown in Table 2 below:

TABLE 287654321Power Command and Access Type IEIoctet 1ATCEPCFPC_EPCPOWER LEVELmodeoctet 2
The purpose of this information element (IE) is to provide the power level to be used by an MS and the indication that the MS can avoid the transmission of handover access. The various fields are defined in Table 3 as follows:

TABLE 3ATC (Access Type Control) (octet 2)Bit 80Sending of Handover access is mandatory1Sending of Handover access is optionalEPC_mode (octet 2)The EPC mode field (octet 2) indicates whether the assignedchannel(s) shall be in enhanced power control (EPC) mode.It is only valid for channels on which EPC may be used.It is coded as follows:ValueChannel(s) not in EPC modeChannel(s) in EPC modeFPC_EPC (octet 2)The FPC_EPC field (octet 2) has different interpretationdepending on the channel mode of the assigned channel (s)and the value of the EPC mode field.If the channel mode is such that fast power control (FPC)may be used, the FPC_EPC field indicates whether FastMeasurement Reporting and Power Controlmechanism is used. It is coded as follows:Value0FPC not in use1FPC in useIf the channel mode is such that EPC may be used andthe EPC mode field indicates that the channel is inEPC mode, the FPC_EPC field indicates whether EPCshall be used for uplink power control. It is codedas follows:Value0EPC not in use for uplink power control1EPC in use for uplink power controlPower level (octet 2)The power level field is coded as the binaryRepresentation of the “power control level”, see3GPP TS 3GPP TS 45.005. This value shall beused by the mobile station According to 3GPPTS 45.008.Range: 0 to 31.
In accordance with one embodiment of the invention, the invention makes use of the existing “POWER LEVEL” parameter. However, this POWER LEVEL parameter is currently only used to control the MS output power for the circuit-switched (CS) resources after handover, until an updated power control command is received through the SACCH channel from the new cell. In accordance with one embodiment of the invention, the POWER LEVEL parameter is used as a maximum output power level for packet-switched (PS) traffic after CS handover. More particularly, the initial output power for the CS resources, after CS handover, equals the maximum allowed power at the target cell (or at least close to the maximum allowed power at the target cell). The PMAX parameter used in the PS power control formula equals the maximum power allowed in the cell. This allows the value of the power level parameter being used as PMAX, i.e. if the PMAX is not elsewhere known, the power level parameter value may be read from the most recent handover command as a valid value for PMAX. Thus, the power level parameter is a different parameter from PMAX, but the power level parameter may be used to initialize PMAX.

Alternate embodiments are also illustrated inFIG. 3, where the power level parameter is provided via signaling messages. After DTM handover, the terminal306shall receive a message such as a system information6(SI6)308or DTM information310message to check whether or not DTM is supported in the new cell. For example, such a DTM information message was illustrated inFIG. 2as the DTM information message226. In accordance with various embodiments of the invention, a power level parameter300B,300C used as PMAX may be provided in such an SI6308and/or DTM information310message respectively. In these embodiments, the power level parameter300B,300C represents a new parameter to add to such signaling messages.

Another alternative embodiment is to use a specific default value312for the PMAX parameter. Such a default value312may be stored at the terminal306, or otherwise accessible to the terminal from the network or elsewhere. An example of such a default value312may be, for example, +30 dBm for the GSM 1900 MHz frequency band. Other predetermined values may be used, and any particular default value312may be used depending on the particular network system (e.g., GSM 400, GSM 900, GSM 850, GSM 700, GSM 1900, DCS 1800, etc.). The default value312may also be set equal to the terminal maximum output power. Consistent and known PS output power would be reached even if the PMAX parameter were not available, such as after a CS handover. However, any cell-specific lower maximum output power could be achieved by setting the PS power control parameter “alpha” to zero, and the other power control parameters according to the intended maximum output power.

FIG. 4is a flow diagram illustrating one embodiment for effecting PS power control for DTM after CS handover in accordance with the present invention. Optionally a PS session and at least a CS session are in progress, as indicated by blocks400,402. The power level parameter as included in the handover command is set to an appropriate value, as indicated at block404. The CS handover is performed406, and the CS session continues408in the new cell. The terminal sets410the PMAX parameter to the value of the power level parameter received from the handover command. The received power level parameter may be used to determine the PMAX value in calculating PCH, as shown in Equation 1. The DTM is established412, such as by providing the DTM information from the BSS to the terminal, sending a DTM request from the terminal to the BSS, and transmitting a packet assignment command from the BSS to the terminal. The PS session then continues414in the new cell, using the calculated terminal output power level.

FIG. 5Aillustrates another flow diagram of an embodiment for effecting PS power control for DTM after CS handover in accordance with the present invention. Optionally a PS and at least a CS session are in progress, as indicated by blocks500,502. The CS handover is performed504, and the CS session continues506in the new cell. As depicted at block508, the power level parameter is included in a signaling message(s), such as the DTM information message, SI6message, or other signaling message. The DTM is established512, and the PS session then continues514in the new cell using the calculated terminal output power level, and specifically using the power level parameter value, as received from the SI6message or DTM information message, for the PMAX parameter.

FIG. 5Billustrates another flow diagram of an embodiment for effecting PS power control for DTM after CS handover in accordance with the present invention. Optionally a PS and at least a CS session are in progress, as indicated by blocks550,552. The CS handover is performed554, and the DTM is established556. In this embodiment, the PS session continues558in the new cell using a default PMAX parameter if no other PMAX value is available, such as if no power level parameter is provided via the network.

Hardware, firmware, software or a combination thereof may be used to perform the functions and operations in accordance with the invention. The terminals in accordance with the invention include any communication device capable of communicating over-the-air (OTA) with wireless networks. Such terminals include, for example, mobile phones, Personal Digital Assistants (PDAs), computing devices, and other wireless communicators. A representative system in which the present invention may be implemented or otherwise utilized is illustrated inFIG. 6.

The system includes one or more terminals600A such as, for example, a mobile phone602, PDA604, computing device606, or other communication device608capable of OTA communication. The terminal600A utilizes computing systems to control and manage the conventional device activity as well as the functionality provided by the present invention. For example, the representative terminal600B includes a processing/control unit610, such as a microprocessor, controller, reduced instruction set computer (RISC), or other central processing module. The processing unit610need not be a single device, and may include one or more processors. For example, the processing unit may include a master processor and one or more associated slave processors coupled to communicate with the master processor.

The processing unit610controls the basic functions of the terminal600B as dictated by programs available in the program storage/memory612. The storage/memory612may include an operating system and various program and data modules associated with the present invention. In one embodiment of the invention, the programs are stored in non-volatile electrically-erasable, programmable read-only memory (EEPROM), flash ROM, etc., so that the programs are not lost upon power down of the terminal. The storage612may also include one or more of other types of read-only memory (ROM) and programmable and/or erasable ROM, random access memory (RAM), subscriber interface module (SIM), wireless interface module (WIM), smart card, or other fixed or removable memory device/media. The programs may also be provided via other media613, such as disks, CD-ROM, DVD, or the like, which are read by the appropriate media drive(s)614. The relevant software for carrying out terminal operations in accordance with the present invention may also be transmitted to the terminal600B via data signals, such as being downloaded electronically via one or more networks, such as the data network615or other data networks, and an intermediate wireless network(s)616.

For performing other standard terminal functions, the processor610is also coupled to user-interface (UI)618associated with the terminal600B. The UI618may include, for example, a keypad, function buttons, microphone, joystick, scrolling mechanism (e.g., mouse, trackball), touch pad/screen, or other user entry mechanisms (not shown). These and other UI components are coupled to the processor610as is known in the art. A display device620may also be associated with the terminal600B.

The illustrated terminal600B also includes conventional circuitry for performing wireless transmissions over the wireless network(s)616. The DSP622may be employed to perform a variety of functions, including analog-to-digital (A/D) conversion, digital-to-analog (D/A) conversion, speech coding/decoding, encryption/decryption, error detection and correction, bit stream translation, filtering, etc. The transceiver624transmits outgoing radio signals and receives incoming radio signals, generally by way of an antenna626.

In one embodiment, the storage/memory612stores the various client programs used in connection with the present invention. For example, the storage/memory612includes storage to store the maximum power control level632provided via the network616to the terminal600B. The storage/memory612also includes an output power calculation module630, operable in connection with the processor610in one embodiment of the present invention. In one embodiment, the output power calculation module630includes software and/or firmware operable with the processor610to define the terminal output power level that is to be used by the terminal, such as performing the calculation shown in Equation 1 above. Based on the defined value, the output power generation module634establishes the proper output power for which the transceiver624is to transmit communication signals. These terminal modules are representative of the types of functional modules that may be provided on a terminal in accordance with the invention, and are not intended to represent an exhaustive list.

FIG. 6also depicts a representative computing system650operable on the network for generating the messages to the terminal to provide at least the maximum terminal output power level for use by the terminal in establishing the proper terminal output power. In one embodiment of the invention, the computing system650represents functionality at a Base Station System (BSS). Alternatively, the functionality described for the computing system650inFIG. 6may be provided in other network entities that communicate assignment messages and/or system information messages to terminals.

In one embodiment, the computing system650includes a processing arrangement652, which may be coupled to the storage/memory654. The processor652carries out a variety of standard computing functions as is known in the art, as dictated by software and/or firmware instructions. The storage/memory654may represent firmware, media storage, and/or memory. The processor652may communicate with other internal and external components through input/output (I/O) circuitry656. The computing system650may also include media drives658, such as hard and floppy disk drives, CD-ROM drives, DVD drives, and other media660capable of reading and/or storing information. In one embodiment, software for carrying out the operations at the computing system650in accordance with the present invention may be stored and distributed on CD-ROM, diskette, removable memory, or other form of media capable of portably storing information, as represented by media devices660. Such software may also be transmitted to the system650via data signals, such as being downloaded electronically via a network such as the data network615, Local Area Network (LAN) (not shown), wireless network616, and/or any combination thereof.

In accordance with one embodiment of the invention, the storage/memory654and/or media devices660store the various programs and data used in connection with the present invention. For example, the message generation module662is operable with the processor652to generate the various messages that incorporate the power level parameter for transmission to the terminal600B. The message generation module662may therefore generate the handover command, and/or signaling messages (e.g., DTM information; SI6; etc.) that include the power level parameter. The illustrated computing system650also includes DSP circuitry666, at least one transceiver668, and an antenna670for facilitating the communications with the terminal600B and/or other devices.

Using the foregoing specification, some embodiments of the invention may be implemented as a machine, process, or article of manufacture by using standard programming and/or engineering techniques to produce programming software, firmware, hardware or any combination thereof. Any resulting program(s), having computer-readable program code, may be embodied within one or more computer-usable media such as memory devices or transmitting devices, thereby making a computer program product, computer-readable medium, or other article of manufacture according to the invention. As such, the terms “computer-readable medium” and/or “computer program product” as used herein are intended to encompass a computer program existing permanently, temporarily, or transitorily on any computer-usable medium such as on any memory device or in any transmitting device.

For example, one embodiment of the invention includes a computer-readable medium having instructions stored thereon that are executable by a computer system for controlling the output power level at a terminal. The instructions executable by the computing system and stored on the computer-readable medium perform steps including receiving a channel assignment message at the terminal from the network where the channel assignment message includes a first maximum terminal output power level indicator, defining a terminal output power level to be used as the terminal's output power level based on the first maximum terminal output power level indicator received via the channel assignment message, setting a terminal output power level of the terminal to correspond to the defined terminal output power level, and transmitting data from the terminal at the terminal output power level.

From the description provided herein, those skilled in the art are readily able to combine software created as described with appropriate general purpose or special purpose computer hardware to create a computer system and/or computer subcomponents embodying the invention, and to create a computer system and/or computer subcomponents for carrying out the method of the invention.

Thus, the present invention provides various systems, apparatuses, computer program products, and methods for controlling the output power level of over-the-air (OTA) transmission signals from a terminal operable on a network. In one method, a power level parameter is provided to the terminal via a circuit-switched (CS) handover command, and the power level parameter for packet-switched (PS) power control is copied or otherwise utilized for PS traffic after CS handover. In a more particular embodiment, a packet-switched (PS) output power level to be used as the terminal's output power level for PS traffic after CS handover is defined, using the power level parameter received via the CS handover command. In another particular embodiment, defining a PS output power level involves using a default value in defining the PS output power level if the power level parameter is not provided via the CS handover command. In accordance with another embodiment, a method is provided for controlling the output power level of over-the-air (OTA) transmission signals from a terminal operable on a network. At least one signaling message is generated at the network, and a power level parameter is associated with the signaling message(s). The signaling message(s) is transmitted from the network to the terminal, and a PS output power level to be used as the terminal's output power level for PS traffic after CS handover is defined, using the power level parameter received via the at least one signaling message. In a more particular embodiment, the signaling message(s) determines whether or not dual transfer mode (DTM) is supported in the new cell. In another particular embodiment, the signaling message(s) includes a point-to-point system information message, such as, for example, a system information6(SI6) message, a DTM information message, etc. In another particular embodiment, defining a PS output power level involves using a default value in defining the PS output power level if the power level parameter is not provided via the signaling message.