System and method for indication of contiguous resource allocations in OFDM-based systems

A mobile station and base station are capable of communicating in a wireless network via a set of contiguous or non-contiguous sub-bands. The base station transmits a resource allocation to the mobile station. The resource allocation message includes a sub-band index (SBI) field, a number of messages field, a contiguous allocation indicator field, or a combination of these. Based on the SBI field, one or more of the number of messages field and contiguous allocation indicator field, the mobile station can identify the set of sub-bands allocated to it by the base station.

TECHNICAL FIELD OF THE INVENTION

The present application relates generally to wireless communications and, more specifically, to a system and method for indicating a contiguous resource allocation in an orthogonal frequency division multiplexing system.

BACKGROUND OF THE INVENTION

In a cellular communications system, a certain geographical region is divided into regions referred to as cells. The mobile stations (MSs) in each cell are served by a single base station (BS). A BS transmits information to a particular MS (or a group of MSs) in its cell on the radio path referred to as the downlink (DL), while the MSs transmit information to the BS on the radio path referred to as the uplink (UL). The transmissions on the UL and the DL may be on the same time intervals but on different frequency bands, referred to as frequency division duplexing (FDD), or on the same frequency band but during non-overlapping time intervals, referred to as time division duplexing (TDD). In some systems, the transmissions on the DL and UL are based on Orthogonal Frequency Division Multiplexing (OFDM) modulation. In OFDM modulation, the available bandwidth for the radio link (DL or UL) is divided into a large number of smaller-bandwidth units referred to as sub-carriers (SCs), onto which the information to be transmitted is embedded.

Due to OFDM modulation, on the UL, if the MSs in a cell simultaneously use non-overlapping SC sets to make transmissions to the BS, then when received at the BS, the transmission from any MS is rendered orthogonal to the transmission from any other MS. For example, MS(i) uses SC set {Si} to perform UL transmissions to the BS; and the SC sets used by different MSs are non-overlapping. Then, when received at the MS, the transmissions from MS(i) on SC set {Si} are not interfered with by any of the transmissions to the BS from any of the MSs j, where j≠i.

Similarly, on the DL, if the BS uses non-overlapping SCs to make simultaneous transmissions to different MSs, then at any MS, the transmissions meant for other MSs appear orthogonal to the transmissions meant for it. For example, the BS can transmit to MS(i) using SC set {Si}, and use non-overlapping SC sets to perform transmissions to various MSs. Then, when received at MS(i), the transmissions from the BS on SC set {Si} are not interfered with by any of the transmissions from the BS to any of the MSs j, where j≠i. This property of OFDM modulation allows simultaneous communications between several MSs and the BS on the UL, and the BS and several MSs on the DL.

SUMMARY OF THE INVENTION

A mobile station capable of communicating with a base station in a wireless network is provided. The mobile station includes a plurality of antennas and a controller coupled to the plurality of antennas. The controller is configured to receive an allocation of a set of sub-bands for use in communicating with the base station. The controller receives a resource allocation message from the base station. The resource allocation message includes a sub-band index (SBI) field and at least one message field. The controller can use the SBI field and the at least one message field to determine the set of sub-bands.

A method for communicating with a base station in a wireless network is provided. The method includes receiving a resource allocation message from a base station. The resource allocation message is configured to identify an allocation of a set of sub-bands for use in communicating with the base station. The resource allocation message includes a sub-band index (SBI) field and at least one of message field. The method further includes determining the set of sub-bands using the SBI field and the at least one message field.

A base station capable of communicating with a mobile station in a wireless network is provided. The base station includes a plurality of antennas and a controller coupled to the plurality of antennas. The controller is configured to allocate a set of sub-bands to the mobile station. The controller is configured to transmit a resource allocation message to the mobile station. The resource allocation message includes a sub-band index (SBI) field and at least one message field. The resource allocation message is configured to be used to determine the set of sub-bands based on the SBI field and the at least one message field.

A method for communicating with a subscriber station in a wireless network is provided. The method includes transmitting at least one resource allocation message to the at least one subscriber station. The resource allocation message is configured to identify an allocation of a set of sub-bands including at least one sub-band for use in communicating by the at least one subscriber station. The resource allocation message includes a sub-band index (SBI) field, and at least one message field. The at least one resource allocation message is configured to be used to determine the set of sub-bands including at least one sub-band based on the SBI field and the at least one message field.

DETAILED DESCRIPTION OF THE INVENTION

With regard to the following description, it is noted that the LTE term “node B” is another term for “base station” used below. Further, the term “cell” is a logical concept that can represent a “base station” or a “sector” that belongs to a “base station”. In the present disclosure, “cell” and “base station” are used interchangeably to indicate the actual transmission units (may be “sector” or “base station” and the like) in the wireless system. Also, the LTE term “user equipment” or “UE” is another term for “subscriber station” used below. It is noted that in all the following figures, some optional features are explicitly marked while some are omitted for clarity purpose.

FIG. 1illustrates exemplary wireless network100that is capable of decoding data streams according to one embodiment of the present disclosure. In the illustrated embodiment, wireless network100includes base station (BS)101, base station (BS)102, and base station (BS)103. Base station101communicates with base station102and base station103. Base station101also communicates with Internet protocol (IP) network130, such as the Internet, a proprietary IP network, or other data network.

Base station102provides wireless broadband access to network130, via base station101, to a first plurality of subscriber stations within coverage area120of base station102. The first plurality of subscriber stations includes subscriber station (SS)111, subscriber station (SS)112, subscriber station (SS)113, subscriber station (SS)114, subscriber station (SS)115and subscriber station (SS)116. Subscriber station (SS) may be any wireless communication device, such as, but not limited to, a mobile phone, mobile PDA and any mobile station (MS). In an exemplary embodiment, SS111may be located in a small business (B), SS112may be located in an enterprise (E), SS113may be located in a WiFi hotspot (HS), SS114may be located in a residence, SS115may be a mobile (M) device, and SS116may be a mobile (M) device.

Base station103provides wireless broadband access to network130, via base station101, to a second plurality of subscriber stations within coverage area125of base station103. The second plurality of subscriber stations includes subscriber station115and subscriber station116. In alternate embodiments, base stations102and103may be connected directly to the Internet or other controller unit by means of a wired broadband connection, such as an optical fiber, DSL, cable or T1/E1 line, rather than indirectly through base station101.

In other embodiments, base station101may be in communication with either fewer or more base stations. Furthermore, while only six subscriber stations are shown inFIG. 1, it is understood that wireless network100may provide wireless broadband access to more than six subscriber stations. It is noted that subscriber station115and subscriber station116are on the edge of both coverage area120and coverage area125. Subscriber station115and subscriber station116each communicate with both base station102and base station103and may be said to be cell-edge devices interfering with each other. For example, the communications between BS102and SS116may be interfering with the communications between BS103and SS115. Additionally, the communications between BS103and SS115may be interfering with the communications between BS102and SS116.

In an exemplary embodiment, base stations101-103may communicate with each other and with subscriber stations111-116using an IEEE-802.16 wireless metropolitan area network standard, such as, for example, an IEEE-802.16e standard. In another, embodiment, however, a different wireless protocol may be employed, such as, for example, a HIPERMAN wireless metropolitan area network standard. Base station101may communicate through direct line-of-sight or non-line-of-sight with base station102and base station103, depending on the technology used for the wireless backhaul. Base station102and base station103may each communicate through non-line-of-sight with subscriber stations111-116using OFDM and/or OFDMA techniques.

Base station102may provide a T1 level service to subscriber station112associated with the enterprise and a fractional T1 level service to subscriber station111associated with the small business. Base station102may provide wireless backhaul for subscriber station113associated with the WiFi hotspot, which may be located in an airport, café, hotel, or college campus. Base station102may provide digital subscriber line (DSL) level service to subscriber stations114,115and116.

Subscriber stations111-116may use the broadband access to network130to access voice, data, video, video teleconferencing, and/or other broadband services. In an exemplary embodiment, one or more of subscriber stations111-116may be associated with an access point (AP) of a WiFi WLAN. Subscriber station116may be any of a number of mobile devices, including a wireless-enabled laptop computer, personal data assistant, notebook, handheld device, or other wireless-enabled device. Subscriber station114may be, for example, a wireless-enabled personal computer, a laptop computer, a gateway, or another device.

In accordance with an embodiment of the present disclosure, one or more of base stations101-103and/or one or more of subscriber stations111-116include a receiver that is operable to decode a plurality of data streams received as a combined data stream from a plurality of transmit antennas using Minimum Mean Square Equalizer-Successive Interference Cancellation (MMSE-SIC) algorithm. As described in more detail below, the receiver is operable to determine a decoding order for the data streams based on a decoding prediction metric for each data stream that is calculated based on a strength-related characteristic of the data stream. Thus, in general, the receiver is able to decode the strongest data stream first, followed by the next strongest data stream, and so on. As a result, the decoding performance of the receiver is improved as compared to a receiver that decodes streams in a random or pre-determined order without being as complex as a receiver that searches all possible decoding orders to find the optimum order.

Also, the coverage areas associated with base stations are not constant over time and may be dynamic (expanding or contracting or changing shape) based on changing transmission power levels of the base station and/or the subscriber stations, weather conditions, and other factors. In an embodiment, the radius of the coverage areas of the base stations, for example, coverage areas120and125of base stations102and103, may extend in the range from less than 2 kilometers to about fifty kilometers from the base stations.

As is well known in the art, a base station, such as base station101,102, or103, may employ directional antennas to support a plurality of sectors within the coverage area. InFIG. 1, base stations102and103are depicted approximately in the center of coverage areas120and125, respectively. In other embodiments, the use of directional antennas may locate the base station near the edge of the coverage area, for example, at the point of a cone-shaped or pear-shaped coverage area.

The connection to network130from base station101may comprise a broadband connection, for example, a fiber optic line, to servers located in a central office or another operating company point-of-presence. The servers may provide communication to an Internet gateway for internet protocol-based communications and to a public switched telephone network gateway for voice-based communications. In the case of voice-based communications in the form of voice-over-IP (VoIP), the traffic may be forwarded directly to the Internet gateway instead of the PSTN gateway. The servers, Internet gateway, and public switched telephone network gateway are not shown inFIG. 1. In another embodiment, the connection to network130may be provided by different network nodes and equipment.

In accordance with an embodiment of the present disclosure, one or more of base stations101-103and/or one or more of subscriber stations111-116include a receiver that is operable to decode a plurality of data streams received as a combined data stream from a plurality of transmit antennas using an MMSE-SIC algorithm. As described in more detail below, the receiver is operable to determine a decoding order for the data streams based on a decoding prediction metric for each data stream that is calculated based on a strength-related characteristic of the data stream. Thus, in general, the receiver is able to decode the strongest data stream first, followed by the next strongest data stream, and so on. As a result, the decoding performance of the receiver is improved as compared to a receiver that decodes streams in a random or pre-determined order without being as complex as a receiver that searches all possible decoding orders to find the optimum order.

FIG. 2illustrates an exemplary base station in greater detail according to one embodiment of the present disclosure. The embodiment of base station102illustrated inFIG. 2is for illustration only. Other embodiments of the base station102could be used without departing from the scope of this disclosure.

Base station102comprises base station controller (BSC)210and base transceiver subsystem (BTS)220. A base station controller is a device that manages wireless communications resources, including the base transceiver subsystems, for specified cells within a wireless communications network. A base transceiver subsystem comprises the RF transceivers, antennas, and other electrical equipment located in each cell site. This equipment may include air conditioning units, heating units, electrical supplies, telephone line interfaces and RF transmitters and RF receivers. For the purpose of simplicity and clarity in explaining the operation of the present disclosure, the base transceiver subsystems in each of cells120and125and the base station controller associated with each base transceiver subsystem are collectively represented by BS102and BS103, respectively.

BSC210manages the resources in cell site121, including BTS220. BTS220comprises BTS controller225, channel controller235, transceiver interface (IF)245, RF transceiver unit250, and antenna array255. Channel controller235comprises a plurality of channel elements, including exemplary channel element240. BTS220also comprises a memory260. The embodiment memory260included within BTS220is for illustration only. Memory260can be located in other portions of BS102without departing from the scope of this disclosure.

BTS controller225comprises processing circuitry and memory capable of executing an operating program that communicates with BSC210and controls the overall operation of BTS220. Under normal conditions, BTS controller225directs the operation of channel controller235, which contains a number of channel elements, including channel element240, that perform bi-directional communications in the forward channels and the reverse channels. A forward channel refers to a channel in which signals are transmitted from the base station to the mobile station (also referred to as DOWNLINK communications). A reverse channel refers to a channel in which signals are transmitted from the mobile station to the base station (also referred to as UPLINK communications). In an advantageous embodiment of the present disclosure, the channel elements communicate according to an OFDMA protocol with the mobile stations in cell120. Transceiver IF245transfers the bi-directional channel signals between channel controller240and RF transceiver unit250. The embodiment of RF transceiver unit250as a single device is for illustration only. RF transceiver unit250can separate transmitter and receiver devices without departing from the scope of this disclosure.

Antenna array255transmits forward channel signals received from RF transceiver unit250to mobile stations in the coverage area of BS102. Antenna array255also sends to transceiver250reverse channel signals received from mobile stations in the coverage area of BS102. In some embodiments of the present disclosure, antenna array255is a multi-sector antenna, such as a three-sector antenna in which each antenna sector is responsible for transmitting and receiving in a 120° arc of coverage area. Additionally, RF transceiver250may contain an antenna selection unit to select among different antennas in antenna array255during transmit and receive operations.

According to some embodiments of the present disclosure, BTS controller225is operable to execute programs, such as an operating system (OS) and processes for resource allocations, stored in a memory260. Memory260can be any computer readable medium, for example, the memory260can be any electronic, magnetic, electromagnetic, optical, electro-optical, electro-mechanical, and/or other physical device that can contain, store, communicate, propagate, or transmit a computer program, software, firmware, or data for use by the microprocessor or other computer-related system or method. Memory260comprises a random access memory (RAM) and another part of memory260comprises a Flash memory, which acts as a read-only memory (ROM).

BSC210is operable to maintain communications between BS102and BS101and BS103. BS102communicates to BS101and BS103via the wireless connection131. In some embodiments, the wireless connection131is wire-line connection.

FIG. 3illustrates an exemplary wireless subscriber station according to embodiments of the present disclosure. The embodiment of wireless subscriber station116illustrated inFIG. 3is for illustration only. Other embodiments of the wireless subscriber station116could be used without departing from the scope of this disclosure.

Radio frequency (RF) transceiver310receives from antenna305an incoming RF signal transmitted by a base station of wireless network100. Radio frequency (RF) transceiver310down-converts the incoming RF signal to produce an intermediate frequency (IF) or a baseband signal. The IF or baseband signal is sent to receiver (RX) processing circuitry325that produces a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal. Receiver (RX) processing circuitry325transmits the processed baseband signal to speaker330(i.e., voice data) or to main processor340for further processing (e.g., web browsing).

Transmitter (TX) processing circuitry315receives analog or digital voice data from microphone320or other outgoing baseband data (e.g., web data, e-mail, interactive video game data) from main processor340. Transmitter (TX) processing circuitry315encodes, multiplexes, and/or digitizes the outgoing baseband data to produce a processed baseband or IF signal. Radio frequency (RF) transceiver310receives the outgoing processed baseband or IF signal from transmitter (TX) processing circuitry315. Radio frequency (RF) transceiver310up-converts the baseband or IF signal to a radio frequency (RF) signal that is transmitted via antenna305.

In some embodiments of the present disclosure, main processor340is a microprocessor or microcontroller. Memory360is coupled to main processor340. According to some embodiments of the present disclosure, part of memory360comprises a random access memory (RAM) and another part of memory360comprises a Flash memory, which acts as a read-only memory (ROM).

Main processor340executes basic operating system (OS) program361stored in memory360in order to control the overall operation of wireless subscriber station116. In one such operation, main processor340controls the reception of forward channel signals and the transmission of reverse channel signals by radio frequency (RF) transceiver310, receiver (RX) processing circuitry325, and transmitter (TX) processing circuitry315, in accordance with well-known principles.

Main processor340is capable of executing other processes and programs resident in memory360. Main processor340can move data into or out of memory360, as required by an executing process. In some embodiments, the main processor340is configured to execute programs, such as processes for determining resource allocations362. The main processor340can execute processes for determining resource allocations362based on OS program361or in response to a signal received from BS102. Main processor340is also coupled to I/O interface345. I/O interface345provides subscriber station116with the ability to connect to other devices such as laptop computers and handheld computers. I/O interface345is the communication path between these accessories and main controller340.

Main processor340is also coupled to keypad350and display unit355. The operator of subscriber station116uses keypad350to enter data into subscriber station116. Display355may be a liquid crystal display capable of rendering text and/or at least limited graphics from web sites. Alternate embodiments may use other types of displays.

FIG. 4illustrates a sub-band with a number of contiguous resource units (CRUs) according to embodiments of the present disclosure. The embodiment of the sub-band400shown inFIG. 4is for illustration only. Other embodiments could be used without departing from the scope of this disclosure.

In the OFDM-based system, the basic time unit over which the transmissions (from BS102to SS111-116, and from SS111-116to BS102) occur is called an OFDM symbol. On the UL, the transmissions by SS111-116are coordinated to ensure that non-overlapping SC sets are being used, and each SS has been instructed, by BS102, as to which SC set to use for transmissions to BS102. Similarly, on the DL, BS102uses non-overlapping SC sets to make transmissions to SS111-116, and the SSs are instructed, by BS102, as to which SC sets to listen to receive the transmissions meant for them.

The instructions to the SSs, whether regarding which SC set to use for UL transmissions, or which SC set on which to receive DL transmissions, are referred to as Resource Allocation Messages. The resource allocation messages are transmitted by BS102on an SC set referred to as the Resource Allocation Region. For example, several resource allocation messages, each meant for a particular SS or a group of SSs, are carried on SCs that are part of the Resource Allocation Region.

Each of SS111-116is aware of the resource allocation region; and each of SS111-116receives, decodes and interprets the resource allocation messages in the resource allocation region to learn about the SC set it is to use for UL transmissions and/or the set on which it is to receive DL transmissions.

The SC sets that are available for transmissions by BS102to SS111-116on the DL, and by SS111-116to BS102on the UL, are classified into two broad categories: distributed resources and contiguous resources. It is first noted that a logical index of a resource is the index with which it is referred to in allocations, and which, along with a convention for translation to physical resources, allows a BS or an SS to determine which physical resource to which the allocation refers.

Distributed resources are collections of distributed resource units, where a Distributed Resource Unit (DRU) is a subset of a known size (in the number of SCs and OFDM symbols), of logical indices of SCs, in which SCs that are contiguous with respect to their logical indices are not physically contiguous with respect to their location in the physical bandwidth of transmission. Transmitting on distributed resources allows the receiver to experience the average channel conditions over the entire, or a relatively large portion of, the total available bandwidth.

Contiguous resources are collections of contiguous resource units, where a Contiguous Resource Unit (CRU)405is a subset of a known size (in the number of SCs and OFDM symbols), of logical indices of SCs consisting of physically contiguous SCs, i.e., in which the component SCs that have contiguous logical indices are also physically contiguous.

The sub-band (SB)400consists of a pre-determined (known to all BSs and all SSs) number of CRUs405, such that the set of SCs in the sub-band are physically contiguous. SB400resources can be utilized in order to perform “frequency selective” transmissions. SB400can span a small portion of the overall available bandwidth, or “sample” a small portion of the overall bandwidth. Due to the fact that the all the SCs in SB400are physically contiguous, the channel conditions across them may be expected to be similar in many cases. An SS, such as SS116, may experience a wide variation in radio channel conditions across the entire bandwidth. SS116can estimate the radio channel conditions across the many SBs400that make up the entire bandwidth, and feed them back to BS102. BS102can then schedule transmissions to the SS116on only the good SBs400.

FIG. 4illustrates one frame in a Worldwide Interoperability for Microwave Access (WiMAX) system. For example, a CRU405consists of an SC-OFDM symbol grid consisting of eighteen physically contiguous SCs per OFDM symbol×six OFDM symbols. The SB400can include four CRUs405; forming a grid of seventy-two contiguous SCs×six OFDM symbols. The 72 SCs in the sub-band are physically contiguous. It will be understood that illustration of SB400comprising six OFDM symbols and four CRUs405, each with eighteen SCs, is for example purposes only and embodiments with different numbers of symbols, CRUs and SCs could be used without departing from the scope of this disclosure. Additionally, due to other numerology, there are twelve SBs in a 10 MHz system, and twenty-four in a 20 MHz system.

The IEEE 802.16e system described in IEEE Std. 802.16e-2005, IEEE Standard for Local and metropolitan area networks,—Part 16: Air Interface for fixed and mobile broadband wireless access systems,—Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands, and IEEE Std. 802.16-2004/Cor1-2005, Corrigendum 1, December 2005, the contents of which hereby are incorporated by reference in their entirety, is an example of an OFDM based system employing some of the above descriptions. In the IEEE 802.16e system, the resource allocation messages are referred to as MAP messages and the resource allocation region is referred to as the MAP-Region.

The IEEE 802.16m system described in IEEE 802.16m-09/0010r1, “Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems”, March 2008, the contents of which hereby are incorporated by reference in their entirety, is another example of an OFDM based system employing the above descriptions. In the IEEE 802.16m system, the following specializations apply.

Focusing on the SB resources, we consider now the issue of allocation of SB resources to SS116, that is, informing SS116to receive transmissions on particular SBs on the DL, or perform transmissions on particular SBs on the UL. In order to utilize SBs to perform transmissions on portions of the bandwidth where the radio link is good, the ability to be able to signal sets of SBs with non-contiguous logical indices is important.

FIG. 5illustrates exemplary radio channel conditions across sub-bands according to embodiments of the present disclosure.FIG. 5depicts a 10 MHz system500. The 10 MHz system500includes twelve SBs400. The radio channel conditions505vary across the SBs400. For example, the radio channel conditions505are poor in SB1400b, SB6400g, SB7400h, and SB8400i. However, the radio channel conditions are good in SB2400c, SB3400d, SB4400e, SB5400f, SB9400j, SB10400kand SB11400l.

FIG. 6illustrates a resource allocation message according to embodiments of the present disclosure. The embodiment of the resource allocation message600shown inFIG. 6is for illustration only. Other embodiments could be used without departing from the scope of this disclosure.

BS102transmits the resource allocation message600to SS116. The resource allocation message600can include a contiguous allocation indicator (CAI)605. The CAI605can be a single- or multi-bit field, referred to as a CONTIGUOUS_ALLOCATION_INDICATOR field, which includes information configured to allow SS116to interpret at least a portion of the resource allocation.

The resource allocation message600can include a number of messages indicator610. The number of messages indicator610can be a multi-bit field, referred to as a NUM_MSGS_CARRYING_ALLOCATION field, which is configured to enable SS116to infer the number of resource allocation messages over which the allocation is carried. The NUM_MSGS_CARRYING_ALLOCATION is configured to be “1” (N=1) or a value that is more than “1” (N>1).

The resource allocation message600can include a Sub-band Index (SBI) field615. The SBI field615can be a multi-bit field that is configured to enable SS116to infer the indices of the allocated SBs.

In some systems, the fields in the resource allocation message can be limited in the size, in number of bits allowed to be used. For example, a total number of distinct allocations of SBs may exceed what can be indicated by the allowed size of the field in a resource allocation message. In some examples, only a portion of the possible allocations are indicated in a single message, and the allocation message is designed with the number of bits to cover the most likely cases. In some examples, the allocation is indicated across multiple messages.

In some embodiments, a concatenation rule is employed. The concatenation rule allows the efficient combination of the SBI field to indicate a wide range of allocations with multiple messages, in a completely flexible way. For example, in the case of twelve SBs and a 7-bit SBI field615, one-hundred twenty-eight (128) combinations of SB allocation can be indicated with the seven bits. However, when two allocation messages are used, according to the concatenation rule, one concatenated allocation message includes fourteen bits for indexing. The first twelve bits can be used as a bit map to convey an arbitrary allocation of twelve SBs.

In some examples, the radio channel conditions for a mobile are similar over the entire bandwidth or a large portion of the bandwidth; these are referred to as “frequency flat” channels. In such examples, BS102is configured to allocate contiguous SBs. Accordingly, SS116is able to interpret the SBI field615depending upon whether or not one makes contiguous or non-contiguous allocations.

FIG. 7illustrates a process for interpreting resource allocations according to embodiments of the present disclosure. The embodiment of the process700shown inFIG. 7is for illustration only. Other embodiments could be used without departing from the scope of this disclosure.

SS116receives the resource allocation message600from BS102. The resource allocation message includes the CAI605, the number of messages indicator610, and the SBI field615. In block705, SS116determines if the number of messages indicator610indicates that the allocation is included in one allocation message or more than one allocation messages. For example, SS116determines if “NUM_MSGS_CARRYING_ALLOCATION=1.”

If SS116determines that more than one message includes the allocation, that is “NUM_MSGS_CARRYING_ALLOCATION>1,” then SS116concatenates the SBI field615in block710. SS116concatenates all the SBI fields615in all the resource allocation messages carrying the allocation. SS116can interpret all or parts of the allocations in the form of a bitmap. For example, each position in the concatenated SBI field615can correspond to a logical index of a particular SB400. A “1” can indicate that the corresponding SB has been allocated and a “0” can indicate that the corresponding SB400has not been allocated. Thereafter, SS116can utilize the allocated SBs for UL and DL communications with BS102.

If SS116determines that only one message includes the allocation, that is “NUM_MSGS_CARRYING_ALLOCATION=1,” then SS116determines a value of the CAI605in block715. Based on the value of the CAI605, such as “CONTIGUOUS_ALLOCATION_INDICATOR=1,” SS116interprets the SBI field615according to a contiguous indexing scheme in block720. The contiguous indexing scheme provides an allocation of SBs400with contiguous logical indices. For example, in the contiguous indexing scheme, a portion of the SBI615can specify the lowest SB logical index in the allocation, another portion of the SBI615can specify the highest SB logical index in the allocation, and the allocation can consists of all SBs400with logical indices that lie between, including the lowest and highest indicated indices. Therefore, SS116can use a portion of the SBI615to identify the beginning of a contiguous allocation of SBs400and another portion of the SBI615to identify the end of the contiguous allocation of SBs400. Thereafter, SS116can utilize the allocated SBs for UL and DL communications with BS102.

Alternatively, based on the value of the CAI605, such as “CONTIGUOUS_ALLOCATION_INDICATOR=0,” SS116interprets the SBI field615according to a non-contiguous indexing scheme in block725. The contiguous indexing scheme provides an allocation of SBs400with non-contiguous logical indices. Thereafter, SS116can utilize the allocated SBs for UL and DL communications with BS102.

FIG. 8illustrates an example of the process for interpreting resource allocations according to embodiments of the present disclosure. The example process800shown inFIG. 8is for illustration only. Other examples could be used without departing from the scope of this disclosure.

SS116receives the resource allocation message600from BS102in a 10 MHz 802.16m system (e.g., twelve SBs400). The resource allocation message includes the CAI605, the number of messages indicator610, and the SBI field615. In block805, SS116determines if the number of messages indicator610indicates that the allocation is included in only one message. For example, SS116determines if “NUM_MSGS_CARRYING_ALLOCATION=1.”

In one example, SS116can determine that the number of messages indicator610indicates that the allocation is included in two messages (i.e., N=2). As such, SS116determines that the allocation is carried in more than one message, that is “NUM_MSGS_CARRYING_ALLOCATION>1” in block805. Therefore, SS116concatenates the SBI field615in block810. SS'116 concatenates the 8-bit SBI field615in the first message and the 8-bit SBI field615in the second message to form a 16-bit SBI field. SS116interprets the first twelve bits of the sixteen bits included in the 16-bit SBI field as a bit map. For example, SS116can interpret the bit map as a truth table, such as:

With 0≦j<12;

Bit position j=0SB j is not allocated;

Bit position j=1SB j is allocated;

In another example, SS116can determine that the number of messages indicator610indicates that the allocation is included in one messages (i.e., N=1). As such, SS116determines that only one message includes the allocation, that is, “NUM_MSGS_CARRYING_ALLOCATION=1” in block805. Therefore, SS116determines a value of the CAI605in block815. Based on the value of the CAI605, such as “CONTIGUOUS_ALLOCATION_INDICATOR=1,” in one example, SS116interprets the SBI field615according to a contiguous indexing scheme in block820. The contiguous indexing scheme provides an allocation of SBs400with contiguous logical indices. SS116uses the first four bits of the 8-bit SBI615to identify a Lowest_SB_Index. Four bits can be enough to indicate sixteen values, wherein only twelve SBs400are available in the 802.16M10MHz system. SS116uses the last four bits of the 8-bit SBI615to identify the Highest_SB_Index. The allocation can consist of all SBs400with logical indices that lie between. The allocation includes the Lowest_SB_Index and Highest_SB_Index such that: Lowest_SB_Index≦SB≦Highest_SB_Index.

Alternatively, based on the value of the CAI605, such as “CONTIGUOUS_ALLOCATION_INDICATOR-0,” SS116interprets the SBI field615according to a non-contiguous indexing scheme in block825. SS116interprets the 8-bit SBI using a look-up table (LUT) or a set of LUTs. For each of the two-hundred fifty-six (256) values of the SBI field615, the LUT indicates a particular combination of SB400allocations.

In some embodiments, the number of messages indicator610(i.e., the NUM_MSGS_CARRYING_ALLOCATION field) is not transmitted as a part of the resource allocation message600. SS116is able to determine the number of resource allocation messages carrying the allocation implicitly through other means. The interpretation conventions remain the same as those inFIG. 7(e.g., blocks710,715,720and725); however, the NUM_MSGS_CARRYING_ALLOCATION field is replaced by knowledge from other means of the number of resource allocation messages carrying the allocation.

FIG. 9illustrates the process for interpreting resource allocations according to embodiments of the present disclosure. The embodiment of the process700shown inFIG. 7is for illustration only. Other embodiments could be used without departing from the scope of this disclosure.

In some embodiments, CONTIGUOUS_ALLOCATION_INDICATOR (i.e., the CAI605) is not included in the resource allocation message. Accordingly, SS116is configured to implicitly determine the CAT605.

SS116receives the resource allocation message600from BS102. The resource allocation message includes the number of messages indicator610, and the SBI field615but does not include the CAI605. In block905, SS116determines if the number of messages indicator610indicates that the allocation is included in only one message. For example, SS116determines if “NUM_MSGS_CARRYING_ALLOCATION=1.”

If SS116determines that more than one message includes the allocation, that is “NUM_MSGS_CARRYING_ALLOCATION>1,” then SS116concatenates the SBI field615in block910. SS116concatenates all the SBI fields615in all the resource allocation messages carrying the allocation. SS116can interpret all or parts of the allocations in form of a bitmap. For example, each position in the concatenated SBI field615can correspond to a logical index of a particular SB400. A “1” can indicate that the corresponding SB has been allocated and a “0” can indicate that the corresponding SB400has not been allocated.

If SS116determines that only one message includes the allocation, that is “NUM_MSGS_CARRYING_ALLOCATION=1,” then SS116interprets the SBI field615according to an indexing scheme in block915. The indexing scheme provides an allocation of SBs400.