Patent Publication Number: US-8526366-B2

Title: Method and apparatus for a scheduler for a macro-diversity portion of a transmission

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. Non-Provisional application Ser. No. 11/933,987, filed Nov. 1, 2007, now U.S. Pat. No. 7,903,604, which claims the benefit of U.S. Provisional Patent Application No. 60/912,661, filed Apr. 18, 2007, U.S. Provisional Patent Application No. 60/913,172, filed Apr. 20, 2007, U.S. Provisional Patent Application No. 60/953,452, filed Aug. 1, 2007, and U.S. Provisional Patent Application No. 60/971,837 filed Sep. 12, 2007, which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     1. Field 
     This invention relates generally to a wireless communication system, and in particular to a wireless broadcast communication system. 
     2. Background 
     Wireless communication networks typically have a plurality of servicing base stations which receive and transmit signals to users&#39; devices within the service area of the respective base stations. Communication between a user and their respective base station is maintained as a user moves about the network service area by handing off the user from one base station to another. 
     Many new services are being offered to customers of wireless communication carriers. One such service is providing customers with multimedia content via the wireless communication network. For example, it is desired to provide audio/video content to customers as they move about the network. 
     Providing multimedia content via wireless communication networks presents several challenges. For example, transmitting multimedia content typically consumes large amounts of a communication system&#39;s bandwidth. Limitations in the amount of bandwidth available in a communication system may limit the amount and variety of content that can be provided, or transmitted, by a communication system. Bandwidth constraints can also be compounded by the addition of overhead messages that may be included in signals transmitted by the communication system. For example, overhead messages may be added to a transmitted signal to provide error correction for the signal. Bandwidth constraints may limit the quality of the transmitted content due to insufficient bandwidth to support robust error correction schemes. The effect of bandwidth limitations on the communication system, such as limiting the variety and quality of the content available, may lead to dissatisfaction to the users. 
     Therefore, there is a need for improved systems, apparatus, and techniques for improving bandwidth utilization in communication systems that provide content, such as multimedia content, to users of the wireless communication network. 
     SUMMARY 
     The present invention includes methods, apparatuses, and systems as described in the written description and claims. In one embodiment, a method of broadcasting content data in a macro-diversity region of a data frame is provided. This method comprises receiving a stream of transport packets, selecting at least one burst size, from amongst a set of a plurality of predetermined burst sizes, allocating one or more data bursts with the selected burst size to the macro-diversity region of the data frame, each data burst comprising at least a portion of the received transport packets and wherein the at least one burst size is selected so as to minimize a number of data bursts allocated to the macro-diversity region, and communicating information regarding the allocation of data bursts to the macro-diversity region for broadcasting a data frame comprising the macro-diversity region from at least a first transmitter. 
     In another embodiment, a method of generating a macro-diversity region in a data frame is provided. This method comprises identifying a plurality of sub-channels and a plurality of symbol periods, wherein a symbol period comprises a plurality of symbols, and wherein each symbol during an individual symbol period is associated with a different one of the plurality of sub-channels; generating a map that includes information that describes data bursts and a size of a map in a subsequent macro-diversity region, wherein the map information is included in at least a first symbol during a first symbol period and wherein a data burst is included in at least a second symbol during the first symbol period. 
     In yet another embodiment, there is provided a method of broadcasting content data in a macro-diversity region of a data frame. This method comprises encapsulating a plurality of transport packets, each transport packet comprising content data; selecting at least one burst size, from amongst a set of a plurality of predetermined burst sizes, and allocating one or more data bursts with the selected burst size to the macro-diversity region of the data frame, each data burst comprising at least a portion of the encapsulated transport packets and wherein the at least one burst size is selected so as to minimize the number of data bursts allocated to the macro-diversity region; and broadcasting from each of at least a first and a second transmitter a signal including the data frame in which the at least one data burst was allocated, such that the signals broadcasted from the first and second transmitter are synchronized. 
     In yet another embodiment, there is provided a scheduler comprising means for receiving a stream of transport packets; means for selecting at least one burst size, from amongst a set of a plurality of predetermined burst sizes; means for allocating one or more data bursts with the selected burst size to the macro-diversity region of the data frame, each data burst comprising at least a portion of the received transport packets and wherein the at least one burst size is selected so as to minimize a number of data bursts allocated to the macro-diversity region; and means for communicating information regarding the allocation of data bursts to the macro-diversity region for broadcasting a data frame comprising the macro-diversity region from at least a first transmitter. 
     In yet another embodiment, there is provided a scheduler comprising an input that receives a plurality of data packets; a processor that selects a burst size from among a set of a plurality of predetermined burst sizes, the selected burst size being the largest burst size that fits within a non-allocated portion of a macro-diversity region of a data frame, allocates the selected burst size to the macro-diversity region of the data frame, updates a size of the non-allocated portion of the macro-diversity region based on the allocated burst, and repeats selecting, allocating, and updating until none of the predetermined burst sizes will fit in the non-allocated portion of the macro-diversity region; and an output configured to communicate the allocation of data bursts. 
     Other features and advantages of the present invention should be apparent after reviewing the following detailed description and accompanying drawings which illustrate, by way of example, aspects of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects, advantages and details of the present invention, both as to its structure and operation, may be gleaned in part by a study of the accompanying exemplary drawings, in which like reference numerals refer to like parts. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
         FIG. 1  is a block diagram of an example network in which a data frame comprising a macro-diversity region may be used for broadcasting data to a plurality of client stations in accordance with an embodiment. 
         FIG. 2  is a block diagram of another example network in which a data frame comprising a macro-diversity region may be used for broadcasting data. 
         FIG. 3  is a diagram illustrating an example frame structure that can be used to transmit data between a BTS and a subscriber station. 
         FIG. 4  is a block diagram of an embodiment of a macro-diversity region control module. 
         FIG. 5  is a block diagram of a macro-diversity region of a frame using Hybrid Automatic Request (HARQ) allocations. 
         FIGS. 6A-C  is a diagram illustrating an example technique of filling a macro-diversity region in a data frame. 
         FIG. 7  is a flow chart illustrating aspects of a technique for allocating data bursts to a macro-diversity region. 
         FIG. 8  is a flow chart of an example embodiment of allocating data bursts to a macro-diversity region based upon selecting subgroups of data burst sizes. 
     
    
    
     DETAILED DESCRIPTION 
     Certain embodiments as disclosed herein provide for methods and systems for communication over a broadband wireless air interface. After reading this description it will become apparent how to implement the invention in various alternative embodiments and alternative applications. However, although various embodiments of the present invention will be described herein, it is understood that these embodiments are presented by way of example only, and not limitation. As such, this detailed description of various alternative embodiments should not be construed to limit the scope or breadth of the present invention as set forth in the appended claims. 
     Methods, apparatuses, and techniques are described for allocating data bursts to a macro-diversity region of a downlink communication signal transmitted from multiple base stations, or base transceiver stations, (BTS), such as, for example, BTSs in a single frequency network (SFN). As is known to those of skill in the art, a SFN refers to a network capable of simultaneously broadcasting the same signal (i.e., the same content) over the same frequency channel from multiple transmitters. Further, as used herein the term “macro-diversity region” refers to a portion of a data frame useable for broadcasting information. Exemplary macro-diversity regions include, for example, a Multicast and Broadcast Services (MBS) region of an Orthogonal Frequency Division Multiple Access (OFDMA) data frame, such as, for example, an OFDMA data frame in accordance with the Worldwide Interoperability for Microwave Access (WiMAX) standards (i.e., the Institute for Electrical and Electronics Engineers (IEEE) 802.16 Working Group on Broadband Wireless Access Standards). A further description of an exemplary macro-diversity region of a data frame is presented below. Further, as used herein the terms macro-diversity region and broadcast region are interchangeable. 
     In one embodiment, data bursts are allocated to the macro-diversity region to broadcast data using the macro-diversity region of a data frame. As used herein, the term data burst refers to a consecutive group of data bits or data packets. In accordance with one embodiment, data bursts are allocated to the macro-diversity region in a manner that optimizes the throughput and overall coding gain of the data transmitted via the macro-diversity region. For example, because there is overhead associated with each individual data burst, decreasing the number of data bursts may decrease the total amount of overhead associated with the macro-diversity region. Decreasing the required overhead, accordingly increases the amount of data that may be transmitted by the data frame and thus the overall throughput (i.e., transmitted data) may be increased. Thus, in accordance with one embodiment, larger data bursts are typically preferred over smaller bursts in allocating data bursts to a macro-diversity region of a data frame. A further description of exemplary methods and systems for allocating data bursts to a data frame is provided in more detail below. 
     In one embodiment, in allocating data bursts to the macro-diversity region, the size for each data burst may be selected from a set of predetermined data burst sizes. These predetermined data burst sizes may be selected, for example, based in part on their coding gain performance. For example, a data burst size of 4800 bits may have a desired, or optimal, coding gain and be the largest of the predetermined burst sizes. Therefore, in such an embodiment, data bursts may be allocated to the macro-diversity region in a manner such that as many data bursts with a size of 4800 bits are allocated to the macro-diversity region as will fit within the macro-diversity region. When the remaining portion of the macro-diversity region is not large enough to fit any additional 4800 bit data bursts, then a smaller data burst size is selected from the set of predetermined burst sizes and as many of data bursts at this new selected burst size are allocated to the macro-diversity region as will fit. This process may then repeat until the remaining non-allocated portion of the macro-diversity region is smaller than the smallest predetermined burst size (e.g., 144 bits), after which this remaining portion may be left empty, nulls may be allocated to it, or smaller sized data bursts may be allocated to it as will be described in further detail below. 
     In one embodiment, the predetermined burst sizes include a 4800 bit burst size, a 3840 bit burst size, a 2800 bit burst size, a 1920 bit burst size, a 960 bit burst size, a 480 bit burst size, a 384 bit burst size, a 288 bit burst size, a 192 bit burst size, and a 144 bit burst size. In this embodiment, the largest burst size, 4800 bit, is first selected and 4800 bit data bursts are allocated to the macro-diversity region until the remaining portion of the macro-diversity region is less that 4800 bits. Then, the next largest burst size that will fit in the remaining portion of the macro-diversity region is selected. This process continues until the macro-diversity region is filled or the remaining non-allocated portion of the macro-diversity region is smaller that any of the predetermined burst sizes (i.e., less than 144 bits). It should be noted that these burst sizes are exemplary only, and in other embodiments other data burst sizes may be selected as the predetermined available burst sizes based upon desired characteristics obtained using the data burst size, for example achieving a desired coding gain using the selected data burst size and/or other factors. 
       FIG. 1  is a block diagram of an example network  100  in which a data frame comprising a macro-diversity region may be used for broadcasting data to a plurality of client stations  132  in accordance with an embodiment. In the example illustrated in  FIG. 1 , the network  100  includes an access service network  105  and at least one client station  132 . In one embodiment, the client station  132  includes a receiver that receives a data frame transmitted from at least one BTS  130  in the access service network  105 . Typically, the client station  132  can play back the received data for observation by a user. Optionally, the client station  132  may also record the received data. 
     As noted, the access service network  105  includes at least one BTS  130 . In the example illustrated in  FIG. 1 , the access service network  105  includes a plurality of BTSs  130 . In one embodiment, BTSs  130  may include an antenna system that is sectorized into one or more sectors with each sector transmitting and receiving signals within a corresponding coverage area, wherein the coverage area of the sector may be the same or less than the total coverage area of the BTS. 
     The access service network  105  may also include an encapsulator module  116 , a single frequency network (SFN) adapter module  120 , and a macro-diversity region control module  150 . In one embodiment, the macro-diversity region control module  150  can be a Multicast and Broadcast Services (MBS) controller capable of describing to the BTSs an MBS region for broadcasting data via a WiMAX OFDMA data frame. An exemplary macro-diversity region control module  150  will be described in more detail below. 
     In one embodiment, the encapsulator module  116  receives Internet Protocol (IP) packets from a network (not shown). The encapsulator module  116  encapsulates the IP packets and outputs transport packets, such as Motion Picture Expert Group 2 (MPEG-2) transport packets. As used herein, a transport packet refers to any type of data packet useable for transporting data, and may use any type of format or protocol in transporting the data. In another embodiment, the encapsulator module  116  can also perform time slicing operation in accordance with the European Telecommunications Standards Institute (ETSI) standard for Digital Video Broadcast-Handheld (DVB-H) along with performing multi-protocol encapsulation with forward error correction (MPE-FEC). Additionally, in an embodiment, the encapsulator module  116  may wrap the packets (e.g., transport packets) with an IP header prior to outputting the wrapped packets. 
     In one embodiment, the output of the encapsulator module  116  is communicated to the single frequency network (SFN) adapter module  120  that receives the MPEG-2 transport packets and inserts time stamping information. In one embodiment, the packets outputted to the SFN adapter module  120  may be transmitted to the SFN adapter module  120  over a network, such as an Ethernet network. In one embodiment, the time stamping information added to the MPEG-2 transport packets enables individual BTSs  130  to be time synchronized to each other. The SFN adapter module  120  may further combine multiple received MPEG-2 transport packets into a larger frame (referred to herein as a “mega-frame”) for transmission by the BTSs  130 . In one embodiment, the output of the SFN module  120  is communicated to the macro-diversity region control module  150  that receives the time stamped MPEG-2 data (e.g., the received MPEG-2 transport packets or mega-frame) and defines a macro-diversity region in a data frame. For example, the macro-diversity region defined can be a Multicast Broadcast Services (MBS) region of an OFDMA data frame, such as, for example, an OFDMA data frame in accordance with the WiMAX standards. A further description of the macro-diversity region is provided below. 
     Information regarding the macro-diversity region may then be communicated to the BTS&#39;s  130 . The BTSs  130  may then build data frames including the defined macro-diversity region using the information received from the macro-diversity region control module  150 . These data frames may be, for example, OFDMA data frames in accordance with the WiMAX standards. The BTSs  130  may then broadcast the OFDMA data frames including the macro-diversity region. Further, the BTSs  130  may be synchronized so that the macro-diversity regions transmitted by the BTSs  130  are identical and synchronized. It should be noted that although in this embodiment, each BTS  130  simultaneously broadcasts a common macro-diversity region, the remainder of the data frames transmitted by each BTS  130  need not include common data. A further description of an exemplary data frame comprising a macro-diversity region is presented below. 
       FIG. 2  is a block diagram of another example network  200  in which a data frame comprising a macro-diversity region may be used for broadcasting data. In the example of  FIG. 2 , a macro-diversity region control module  150  receives packets (e.g., MPEG-2 transport stream packets) from an encapsulator  116  such as an IP encapsulator (for ease of explanation, the encapsulator  116  can be referred to as an IP encapsulator). As with the embodiment of  FIG. 1 , in an embodiment IP encapsulator  116  may wrap the packets (e.g., MPEG-2 transport stream packets) with an IP header and transmit the wrapped packets to the macro-diversity region control module  150  over a network, such as, an Ethernet network. The macro-diversity region control module  150  may also receive configuration information from a configuration management module  202 . The configuration information can include, for example, a list of parameters used by the macro-diversity region control module  150  specifying the incoming traffic from the IP encapsulator  116 , and parameters for outgoing traffic, as well as other management information. 
     The macro-diversity region control module  150  builds the macro-diversity region and communicates the macro-diversity region to an access service network gateway (ASN-GW)  204 . In this embodiment, the macro-diversity region control module  150  delivers the macro-diversity region information to the ASN-GW  204  and the ASN-GW  204  distributes this information to at least one BTS  130 . In another embodiment, the macro-diversity region control module  150  builds the macro-diversity region and communicates the macro-diversity region directly to the BTSs  130  (i.e., the macro-diversity region information from the macro-diversity region control module  150  bypasses the ASN Gateway  204  or, for example, no ASN gateway  204  is included in network  200 ). Additionally, in an embodiment, the macro-diversity control module  150  time stamps the information regarding the macro-diversity region prior to providing the macro-diversity region to the ASN-GW or BTSs  130 . Time stamping the information regarding the macro-diversity region may used by the BTSs  130  in synchronizing the transmission of the macro-diversity region by the BTSs  130 . For example, in an embodiment each BTS  130  in the network  200  may simultaneously transmit a particular macro-diversity region at a time specified by the time stamp. 
     As in the embodiment of  FIG. 1 , the BTSs  130  receive the information regarding the macro-diversity region communicated by the macro-diversity region control module  150  and use the received information to build data frames comprising the macro-diversity region. Further, as in the embodiment of  FIG. 1 , the BTSs  130  may be synchronized so that each BTS  130  simultaneously transmits a common macro-diversity region. As noted above, in an embodiment, the macro-diversity control module  150  may provide a time stamp for each macro-diversity region that the BTSs  130  may use in synchronizing transmission of the macro-diversity control module (e.g., each BTS  130  may transmit the macro-diversity region at the time specified by the time stamp). Additionally, as with the embodiment of  FIG. 1 , although each BTS  130  transmits a data frame comprising a common macro-diversity region, the remainder of the data frames transmitted by each BTS  130  need not (and typically does not) include common data. A further description of an exemplary data frame is presented below. 
     In the example of  FIG. 2 , the macro-diversity region control module  150  is illustrated as a separate entity. Alternatively, the macro-diversity region control module  150  can be co-located with another entity, such as the ASN gateway  204 , or IP encapsulator  116 . Further, referring back to  FIG. 1 , the macro-diversity region control module  150  may be co-located with the SFN adapter module  120  in an embodiment. The choice of the entity on which the macro-diversity region control module  150  functionality resides can vary depending on, for example the infrastructure vendor. In addition, the functionality can be distributed across multiple entities. 
       FIG. 3  is a diagram illustrating an example data frame structure that can be used to transmit data between a BTS  130  and a subscriber station  132 . As illustrated in the example of  FIG. 3 , the data frame  302  structure can be divided into multiple sub-channels  304  (along the vertical axis in  FIG. 3 ), with each sub-channel using a carrier frequency that is orthogonal to the carrier frequencies of other sub-channels. The frame  302  is also divided in time into symbol periods  306  (along the horizontal axis in  FIG. 3 ). Each sub-channel  304  during a symbol period comprises a symbol. A symbol can be any type of signal modulation to transmit information. As illustrated in  FIG. 3 , in a data frame  302 , data may be carried by symbols on each of the sub-channel carrier frequencies  304  simultaneously during individual symbol periods  306 . Further, a group of consecutive symbols may be treated as a symbol groups, such that the frame  302  is split into a fixed number of symbol groups each consisting of a particular number (e.g., 2, 4, etc.) of consecutive symbols. 
     In the example of  FIG. 3 , the data frame  302  includes a preamble  308  during symbol period  0 . During symbol periods  1  and  2 , the data frame  302  includes a frame control header (FCH)  310  and a downlink map (DL-MAP)  312  and uplink map (UL-MAP)  314 . Generally, the FCH  310  includes information about the frame  302  configuration, such as coding schemes, message lengths, usable sub-channels, and the like. The downlink and uplink maps  312  and  314  include information about the location of downlink and uplink content within the data frame  302 . The data frame  302  includes a downlink region  330  and an uplink region  332  defined by the downlink and uplink maps. Included in the downlink region  330  is a downlink data region  336  and a macro-diversity region  340 . While  FIG. 3  illustrates an example of the macro-diversity region  340  being located at the end of the downlink region  330 , in other embodiments the macro-diversity region  340  can be located at other positions in the downlink region  330 . In addition, the macro-diversity region  340  does not need to be continuous, but can be separated into multiple regions within the downlink region  330 . 
     The macro-diversity region  340  includes a macro-diversity region Map  342  that defines the size and content of the macro-diversity region  340 . In one embodiment, the macro-diversity map  342  rather than defining the macro-diversity region  340  for the data frame  302  the Map  342  resides in, the macro-diversity region Map  342  defines the size and content of a macro-diversity region  340  in a subsequent data frame  302  of data. For example, the macro-diversity Map  342  may define the size and content of a macro-diversity region in the next data frame in time (i.e., the frame sent immediately after the data frame in which the map  342  resides), or the second data frame  302  following the current frame, or other subsequent data frames of data. 
       FIG. 4  is a block diagram of an embodiment of a macro-diversity region control module  150 . As shown in the example of  FIG. 4 , the macro-diversity region control module  150  includes an input  402  that receives data, such as MPEG-2 transport stream data packets or mega-frames. As noted above, in an embodiment the data received by the macro-diversity control module  150  may be wrapped in an IP header and be received via a network, such as, an Ethernet network. The input  402  may be, for example, an interface implemented in software, hardware, or any combination thereof. The input  402  communicates the received data to a memory module  404  that receives and temporarily stores the data. The memory module  404  can be many different types of memory devices, such as for example, volatile or non-volatile memory modules, optical or magnetic storage devices, such as hard and floppy disk drives, CD-ROM drives, and magnetic tape drives. 
     The macro-diversity region control module  150  also includes a macro-diversity scheduler  406 . The macro-diversity scheduler  406  selects a burst size from among a set of a plurality of predetermined burst sizes. In one embodiment, the selected burst size is the largest burst size that fits within the non-allocated portion of a macro-diversity region of a data frame. The scheduler  406  populates the selected burst size with at least a portion of the received data from the memory module  404  and allocates the populated selected burst to the macro-diversity region. The scheduler  406  then updates the size of the non-allocated portion of the macro-diversity region based on the allocated burst. The macro-diversity scheduler  406  repeats selecting, populating, allocating, and updating until none of the predetermined burst sizes will fit in the non-allocated portion of the macro-diversity region. The macro-diversity scheduler  406  communicates the populated bursts to an output  408  that communicates the macro-diversity region directly to at least one base station  130 . The output  408  may be, for example, an interface implemented in software, hardware, or any combination thereof. Further, output  408  may be capable of converting the information regarding how to build the macro-diversity region to a protocol prior to communicating the macro-diversity region information. In another embodiment, the macro-diversity scheduler  406  communicates the macro-diversity region information via output  408  to an ASN-GW  204  and the ASN-GW  204  distributes this information to at least one BTS  130 . 
     The macro-diversity scheduler  406  can be implemented with a general purpose processor, a digital signal processor (“DSP”), an application specific integrated circuit (“ASIC”), a field programmable gate array (“FPGA”) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
       FIG. 5  is a block diagram of a macro-diversity region of a frame using Hybrid Automatic Request (HARQ) allocations.  FIG. 5  will be discussed with reference to the above-discussed  FIG. 3 . As shown in  FIG. 5 , the macro-diversity region  340  includes a macro-diversity region Map  342  and a plurality of data burst allocations  506 . Each of these allocated data bursts  506  may also be referred to herein as a HARQ packet or HARQ sub-burst. In one embodiment, the size of each allocated data bursts  506  is selected from a set of predetermined sizes. For example, the size of each allocated data bursts  506  may be selected from the set of sizes of 4800, 3840, 2880, 1920, 960, 480, 384, 288, 192, 144 bits. It is noted that the entire portion of the macro-diversity region  340  that is not occupied by the Map  342 , including the symbol periods  306  for the sub-channel carrier frequencies  304  immediately below the MAP  342 , can be allocated to data bursts. In other words, a single symbol period may include some sub-channels that carry Map  342  information and other sub-channels that carry data. 
     Larger burst sizes generally provide higher error protection. As noted above, in an embodiment, macro-diversity region Map  342  describes the macro-diversity region  340  including, for example, the size and location of the data burst allocations  506  within the macro-diversity region  340 . Accordingly, in an embodiment, the size of the macro-diversity region Map  342  may depend, in part, on the number of data bursts  506  allocated to the macro-diversity region  340  of the data frame  302 . Thus, using larger data burst sizes may also reduce the size of the macro-diversity region Map  342  and increase data throughput. 
     In an embodiment, a constant amount of overhead is introduced for each data burst  506  allocated to the macro-diversity region  340 . For example, in one embodiment there are 16 error detection bits, such as Cyclic Redundancy Check (CRC) bits, of overhead and one Information Element (IE) that is 56 bits added to the macro-diversity Map  342  for each data burst  506  allocated to the macro-diversity region  340 . Thus, in an embodiment, the macro-diversity region control module  150  can select larger and accordingly less data bursts  506  for the macro-diversity region to minimize the amount overhead and as such increase data throughput. In one example, the predetermined set of data burst  506  sizes are 144, 192, 288, 384, 480, 960, 1920, 2880, 3840, and 4800 bits. The data bursts  506  can be selected from the predetermined set of sizes to fill, or nearly fill, a given macro-diversity region  340 . It should be noted that this is but one example, and in other embodiments the amount of overhead introduced for each data burst may be variable. 
     As noted, larger HARQ burst sizes generally provide improved error protection. In general, it is noted that: (1) for large data bursts  506 , i.e., data burst greater than or equal to 960 bits, the coding performance is very good and only increases slightly with increases in the data burst  506  size; and (2) for small data bursts  506 , i.e., data burst less than 960 bits, the coding performance increases rapidly with increases in the burst size. While it is generally preferred to use larger data burst sizes  506 , this needs to be balanced against coding performance fluctuations caused by using different data burst  506  sizes. 
     In accordance with one embodiment, data bursts  506  are allocated to the macro-diversity region  340  by the macro-diversity region control module  150  by selecting the largest size data burst from a set of predetermined data burst sizes and determining how many, if any, of the selected size data burst will fit in the macro-diversity region  340 . A Map  342  of the macro-diversity region  340  is updated and the data bursts are allocated to the macro-diversity region  340 . Then, the next largest sized data burst is selected and the process continued until the macro-diversity region  340  is full, or the non-allocated portion of the macro-diversity region is smaller than the smallest predetermined data burst size. Any remaining non-allocated region of the macro-diversity region can be left empty, or filled with null data, or other predetermined data. 
     In an embodiment, macro-diversity region  340  may be an MBS region in accordance with WiMAX standards included in an OFDMA data frame. Typically, in an MBS region  340  using HARQ data bursts, the sub-channels  304  located directly below the Map  342  are required to be left empty or unused. As illustrated, however, in  FIG. 5 , in the presently described embodiment, the sub-channels located directly below Map  342  may be used for transmitting data bursts  506 . As noted above, in an embodiment, Map  342  may not describe the data burst allocations to the macro-diversity region  340  in which the Map  342  is located, but instead describe a subsequent macro-diversity region  340 , such as for example, the next macro-diversity region in time, the second macro-diversity region  340  later in time, or some other subsequent macro-diversity region  340 . In an embodiment, this Map  342 , in addition to describing the allocations to the subsequent macro-diversity region  340 , may also include information describing the size of the Map  342  (e.g., in terms of sub-carriers and symbols or symbol groups) that will be included in this subsequent macro-diversity region  340 . Thus, by knowing the size of the Map  342  allocated to the subsequent data frame, and that the first data burst will be allocated immediately below the Map  342 , the location of this first data burst may be identifiable. Accordingly, by including in the Map  342  information regarding the size of the Map  342  allocated to a subsequent data frame along with information regarding the data burst allocations to the macro-diversity region  340 , the sub-carriers  304  located immediately below the Map  342  of the subsequent macro-diversity region  340  may be useable for data bursts. 
     An example technique of filling a macro-diversity region  340  is shown in  FIGS. 6A-C . As shown in  FIG. 6A , the technique starts with the macro-diversity region control module  150  selecting the largest data burst size from a set of predetermined data burst sizes. The macro-diversity region control module  150  then determines the number, if any, of the selected data burst size will fit within the macro-diversity region  340 . If the selected data burst size will not fit within the macro-diversity region then the next largest size data burst from the set of predetermined data burst sizes is selected. 
     In the example of  FIG. 6A , three of the selected data burst sizes  606 ,  608 , and  610  will fit within the macro-diversity region  340 . The macro-diversity region control module  150  determines the amount of information that is needed to identify the data bursts  606 ,  608 , and  610  within the macro-diversity region  340  and generates a Map  604 . Then, the macro-diversity region control module  150  determines if the Map  604  and the three selected data burst  606 ,  608 , and  610  will fit within the macro-diversity region  340 . If the Map  704  and three selected data bursts  606 ,  608 , and  610  do not fit in the macro-diversity region  340  the macro-diversity region control module  150  removes one of the selected data bursts  606 ,  608 , and  612  and updates the Map  604 . If the Map  604  and the three selected data bursts  606 ,  608  and  610  do fit, such as in the example illustrated in  FIG. 6A , then the macro-diversity region control module  150  allocates the selected data bursts (i.e., data bursts  606 ,  608 , and  610 ), and the Map  604  to the macro-diversity region  340 . The macro-diversity region control module  150  then determines the size of non-allocated region  612  that remains in the macro-diversity region  340 . 
     The macro-diversity region control module  150  then selects the next largest data burst size from the set of predetermined data burst sizes. The macro-diversity region control module  150  then determines the number, if any, of the selected data burst size that will fit within the non-allocated region  612  of the macro-diversity region  340 . If the selected data burst size will not fit within the macro-diversity region then the next largest size data burst size from the set of predetermined data burst sizes is selected. 
     In the example of  FIG. 6B , one of the selected data burst size  614  will fit within the non-allocated region  612  of the macro-diversity region  340 . The macro-diversity region control module  150  determines the amount of information that is needed to identify the data burst  614  within the macro-diversity region  340  and generates an updated Map  615 . Then, the macro-diversity region control module  150  determines if the updated Map  615 , the previously allocated data bursts  606 ,  608 , and  610 , and the selected data burst  614  will fit within the macro-diversity region  340 . If the updated Map  615 , the previously allocated data bursts  606 ,  608 , and  610 , and selected data burst  614  do not fit in the macro-diversity region  340  the macro-diversity region control module  150  removes the selected data burst  614  and re-updates the Map  615 . The macro-diversity region control module  150  then selects the next largest data burst size from the set of predetermined data burst sizes and repeats the process of determining if the data burst size fits in the non-allocated region. 
     If the updated Map  615 , the previously allocated data bursts  606 ,  608 , and  610 , and selected data burst  614  do fit in the macro-diversity region  340 , the example illustrated in  FIG. 6B , then the macro-diversity region control module  150  allocates the selected data burst  614  and the updated Map  615  to the macro-diversity region  340 . Note that allocating the updated Map  615  may cause the previously allocated data bursts  606 ,  608 , and  610  to be assigned to different symbols, or symbol groups in the macro-diversity region  340 . The macro-diversity region control module  150  then determines the size of non-allocated region  616  that remains in the macro-diversity region  340 . 
     The macro-diversity region control module  150  then continues the technique by selecting the next largest data burst size from the set of predetermined data burst sizes. The macro-diversity region control module  150  then determines the number, if any, of the selected data burst size will fit within the non-allocated region  616  of the macro-diversity region  340 . If the selected data burst size will not fit within the macro-diversity region then the next largest size data burst from the set of predetermined data burst sizes is selected and repeats the process of determining if the data burst size fits in the non-allocated region. 
     In the example of  FIG. 6C , two of the selected data burst sizes  618  and  620  will fit within the non-allocated region  616  of the macro-diversity region  340 . The macro-diversity region control module  150  determines the amount of information that is needed to identify the data bursts  618  and  620  within the macro-diversity region  340  and generates an updated Map  622 . Then, the macro-diversity region control module  150  determines if the updated Map  622 , the previously allocated data bursts  606 ,  608 ,  610 , and  614 , and the selected data bursts  618  and  620  will fit within the macro-diversity region  340 . If the updated Map  622 , the previously allocated data bursts  606 ,  608 ,  610 , and  614 , and selected data bursts  618  and  620  do not fit in the macro-diversity region  340  the macro-diversity region control module  150  removes one of the selected data bursts  618  and  620  and re-updates the Map  622 . The macro-diversity region control module then determines if the updated Map  622  and data burst fit and if so allocates the updated Map  622  and data burst to the macro-diversity region  340 . 
     If the updated Map  622 , the previously allocated data bursts  606 ,  608 ,  610 , and  614 , and selected data bursts  618  and  620  do fit in the macro-diversity region  340 , the example illustrated in  FIG. 6C , then the macro-diversity region control module  150  allocates the selected data bursts  618  and  620  and the updated Map  622  to the macro-diversity region  340 . Note that the new allocation may assign different symbols to the previously allocated data bursts. The macro-diversity region control module  150  then determines the size of non-allocated region  624  that remains in the macro-diversity region  340 . 
     The above process continues until none of the predetermined data burst sizes will fit within the non-allocated region of the macro-diversity region  340 . For example, in  FIG. 6C , none of the predetermined data burst sizes will fit within the non-allocated region  624  of the macro-diversity region  340 . In one embodiment, the non-allocated region  624  is left empty. In another embodiment, the non-allocated region  624  is filled with null data packets, or other predetermined data. 
     As noted above, in an embodiment, the Map  622  may not describe the data burst allocations to the macro-diversity region  340  in which the Map  622  is located, but instead describe a subsequent macro-diversity region  340 , such as for example, the next macro-diversity region in time, the second macro-diversity region  340  later in time, or some other subsequent macro-diversity region  340 . In an embodiment, this Map  622 , in addition to describing the allocations to the subsequent macro-diversity region  340 , may also include information describing the size of the Map that will be included in the subsequent macro-diversity region  340 . 
       FIG. 7  is a flow chart illustrating aspects of a technique for allocating data bursts to a macro-diversity region as illustrated in  FIGS. 6A-C . Flow begins in block  706  where a macro-diversity control module selects the largest data burst size in a predetermined set of data bursts. Then, in block  708 , the macro-diversity region control module determines the number of data bursts of the selected data burst size that fit within the macro-diversity region. 
     Flow continues to block  710  where the macro-diversity region control module determines if any data burst(s) of the selected size will fit in the macro-diversity region. If no data burst of the selected size fit then flow continues to block  712  where the next largest data burst size is selected. If, in block  710  it is determined that at least one data burst of the selected size fits, flow continues to block  714 . In block  714  the macro-diversity region control module determines an amount of data needed to be added to a Map of the macro-diversity region to identify the additional data bursts that are added to the macro-diversity region. Flow continues to block  716  where the macro-diversity control module determines if the remaining non-allocated portion of the macro-diversity region is large enough for both the additional data bursts and the additional information that needs to be added to update the Map. If the macro-diversity region is not large enough for both the additional data bursts and the additional information that needs to be added to update the Map flow continues to block  718 . In block  718  the number of data bursts is reduced by one. Flow continues to block  720  and the macro-diversity region control module determines if the number of additional data burst is zero. If the umber of data burst is not zero flow continues to block  716  and the macro-diversity region control module determines if the updated Map and number of data burst fit in the non-allocated portion of the macro-diversity region. If in block  720  it is determined that the number of additional data bursts is zero, flow continues to block  712  and the next largest data burst is selected. 
     Returning to block  716 , if the data bursts and information to update the Map fit in the non-allocated portion of the macro-diversity region, flow continues to block  722 . In block  722  the macro-diversity region control module allocates the updated Map and the data burst along with any previously allocated data bursts to the macro-diversity region. Flow then continues to block  724  where it is determined if the macro-diversity region is full, or if all of the data burst sizes in the set of predetermined data burst sizes have been selected. If the macro-diversity region is not full and not all of the predetermined data burst sizes have been selected, flow continues to block  712  where the next data burst size is selected. Returning to block  724 , if the macro-diversity region is full, or all of the data burst sizes have been selected flow continues to block  726  and flow stops. Using this technique, the structure of the macro-diversity region of the downlink frame, as well as the effective number of bits it will carry, can be determined. 
     It should be noted that the technique illustrated in  FIGS. 6A-C , and  7  has been simplified for explanatory purposes and discusses a macro-diversity region  340  in which the map  604 ,  615 , and  622  describes the macro-diversity region  340  in which the map  604 ,  615 , and  622  resides. As noted above, in other embodiments, the map located in a macro-diversity region may be used to describe a subsequent macro-diversity region rather than the macro-diversity region in which the map resides. An explanation regarding how the technique discussed in  FIGS. 6A-C  and  7  may be extended to embodiments in which the map describes subsequent macro-diversity regions is discussed below. 
     As noted above, in an embodiment, the Map included in a macro-diversity region does not describe the data burst allocations to the macro-diversity region in which the Map is located, but instead describes a subsequent macro-diversity region, such as for example, the next macro-diversity region in time, the second macro-diversity region later in time, or some other subsequent macro-diversity region. For example, the techniques may perform a collective check of multiple macro-diversity regions. For example, when data is allocated to a current macro-diversity region, the Map that is updated or adjusted can be in the macro-diversity region of a previous data frame. Thus, as data burst are allocated to the current macro-diversity region and the Map is updated, the technique can be modified to check that the updated Map and data burst allocated in the previous macro-diversity region that carries the update Map still fit. If the updated Map and data burst allocation in the previous macro-diversity region no longer fit then, using the techniques described, the data allocation in the previous macro-diversity region can be adjusted. In one embodiment, if the data allocation and updated Map no longer fit in the previous macro-diversity region then data that was allocated to one of the data burst in the previous macro-diversity region is re-allocated to a later macro-diversity region. In another embodiment, if the data allocation and updated Map no longer fit in the previous macro-diversity region at least a portion of the data that was allocated to one of the data burst in the previous macro-diversity region is eliminated or not transmitted. For example, data included in the smallest data allocation can be eliminated. 
     Additionally, in yet another embodiment, the size and structure of the macro-diversity regions may remain constant over particular periods of time. For example, it may be known that during particular hours of the day the macro-diversity region will be used to broadcast content data (e.g., television or other audio/visual content) and that the amount of content data transmitted during these hours will fit a particular profile. For example, it may be known that during the hours of 7 am until 1 am the macro-diversity region will carry only content data of live television broadcasts in order to permit a larger portion of the data frame (e.g., the DL zone  336  and UL region  332  of the data frame  302  of  FIG. 3 ) to be used for transmitting point to point traffic, such as, for example, voice telephony traffic. However, during the hours of 1 am to 7 am, the amount of point to point traffic may be less, and therefore, the size of the macro-diversity region expanded so that it may carry additional content data (e.g., movies or other content data that need not be transmitted in real time) during these hours. 
     In such an embodiment, the macro-diversity region sizes during these fixed times may be constant and the maps included in each macro-diversity region may be identical in size and structure. Further, in such, an embodiment, there may be a transition frame used when transitioning from one macro-diversity region size to another. For example, in the example, in which size of the macro-diversity region is constant between the hours of 7 am and 1 am and then changes to a different size that remains constant between the hours of 1 am and 7 am, the system may use a transition frame at the hours of 7 am and 1 am when transitioning between macro-diversity region sizes. The size of the macro-diversity region for this transition frame may be, for example, in between the two sizes. In an embodiment using transition frames, the method discussed above with reference to  FIG. 7  may be used for scheduling data bursts in the transition frame. 
     In yet another embodiment, transition frames may be used when transitioning from one macro-diversity region size to another and the maps included in the macro-diversity region may be used for mapping a subsequent macro-diversity region. Thus, in such an embodiment, the map appearing in the macro-diversity region of the transition frame may map a macro-diversity region with the new size, while the map that maps the macro-diversity region of the transition frame may be included in a macro-diversity region prior to the transition frame. In such an embodiment, the size of the map to be transmitted in the macro-diversity region of the transition frame may be known as well as the size permitted for the map that maps the transition frame to be included in the prior frame. This information may then be used in allocating data bursts to the macro-diversity region of the transition frame using a method similar to that described above with reference to  FIG. 7  while ensuring that the map for the transition frame does not exceed its permitted size. 
     Further, in yet another embodiment, the size of the macro-diversity region may be increased by plus or minus (.+−.) a predetermined number of symbol periods (e.g., one) during the regular course of transmitting data using the macro-diversity region. For example, referring back to  FIG. 4 , in an embodiment, data incoming to the macro-diversity region control module  150  may be buffered in memory module  404 . If the amount of data buffered by memory module  404  exceeds a threshold, the macro-diversity scheduler  406 , or some other processor in the system, may determine to increase the size of the macro-diversity region by a particular number of symbol period(s) (e.g., one symbol period). Or, if the amount of data buffered falls below a threshold, the size of the macro-diversity region may be decreased by the particular number of symbol period(s) (e.g., one symbol period). Further, in such an embodiment, a transition frame may be used when transitioning to the new macro-diversity region size. The size and structure of the macro-diversity region for the transition frame may be stored by the macro-diversity region control module in a memory (not shown). For example, the macro-diversity regions control module may store a table that provides the size and structure of the macro-diversity region of the transition frame based on, for example, the sizes of the initial and new macro-diversity regions. Further, in such an embodiment, data bursts may be allocated to the macro-diversity region of this transition frame using a method similar to that discussed above with reference to  FIG. 7 . Additionally, in embodiments in which the map describes a subsequent macro-diversity region, the procedure may be modified in a manner similar to that discussed above. 
     In accordance with another embodiment, HARQ data bursts  506  are allocated to the macro-diversity region  340  by the macro-diversity region control module  150  by selecting subgroups of data burst sizes from a set of predetermined data burst sizes. For example, the subgroups can be selected based upon the data bursts having similar coding performance. In one embodiment, three subgroups are used, a first subgroup comprising a data burst size of 4800 bits; a second subgroup comprising data burst sizes of 960, 1920, 2880, and 3840 bits; and a third subgroup comprising data burst sizes of 144, 192, 288, 384, 480 bits. In this embodiment, the macro-diversity control module  150  determines a number of data bursts from the first subgroup (4800 bits) that will fit in the macro diversity region  340  and allocates these data bursts to the macro-diversity region  340 . The macro-diversity control module  150  then selects the largest data burst size that will fit in the non-allocated region of the macro diversity region  340  from the second subgroup (960, 1920, 2880, and 3840 bits) and allocates a data burst of this selected size to the macro-diversity region  340 . Then, the macro-diversity control module  150  selects the largest data burst size from the third subgroup (144, 192, 288, 384, 480 bits) that will fit in the non-allocated region of the macro diversity region  340  and allocates as many data bursts of this selected size to the macro-diversity region  340  as will fit (i.e., one or two data bursts of this selected size). 
       FIG. 8  is a flow chart of an example embodiment of allocating data bursts to a macro-diversity region based upon selecting subgroups of data burst sizes. Flow begins in block  802  where a set of predetermined data burst sizes are divided into subgroups. The subgroups can be determined by a network administrator or other network entity. The groupings can be based on, for example, that particular sizes have common characteristics such as similar coding gain, or error correction characteristics, or other types of characteristics. Flow continues to block  804  where a macro-diversity region control module selects a first subgroup. Flow continues to block  806  where the macro-diversity region control module determines how many bursts from the selected group will fit in a non-allocated portion of the macro-diversity region. In one embodiment, the largest data burst size in the group is checked first to see if it will fit, and if not, the next largest burst size is checked to see if it will fit, and so on. Once a burst size is located that will fit, the number of bursts of this size that will fit in the non-allocated portion is determined. Flow then continues to block  808  where a Map of the macro-diversity region is updated to reflect the addition of the data bursts to the macro-diversity region. Flow then continues to block  810 . 
     In block  810  the macro-diversity region control module determines if the data burst(s) and updated Map will fit in the non-allocated macro-diversity region. If it is determined that the updated Map and data burst(s) do fit, flow continues to block  812 . In block  812  the macro-diversity region control module allocates the updated Map and the data burst(s) to the macro-diversity region. Flow continues to block  814 . 
     In block  814  the macro-diversity region control module determines if there are any more subgroups. If there are more subgroups flow continues to block  816  and the next subgroup is selected. If there are not any more subgroups flow continues to block  818  and flow stops. 
     Returning to block  810  if the macro-diversity region control module determines that the data burst(s) and Map do not fit in the macro-diversity region flow continues to block  820  where the number of burst(s) is reduced by one. Flow then continues to block  822  and the macro-diversity region control module determines if the number of data bursts is not zero flow continues to block  808  and the Map is updated. If the number of data bursts is zero flow continues to block  814  and flow continues as described above. 
     As with the embodiment of  FIG. 7 , the embodiment of  FIG. 8  is a simplified embodiment provided for explanatory purposes. Further, the embodiment of  FIG. 8  may be modified in a similar manner to that discussed above with reference to  FIG. 7  for embodiments in which the map describes a macro-diversity region in a subsequent frame (rather than the region in which it resides), or the situation in which the size and structure of the macro-diversity region remains constant over periods of time with transition frames used when transition between macro-diversity regions of different sizes, or for combinations thereof (i.e., where transition frames are used and where the maps describe the structure of subsequent macro-diversity regions). For example, for embodiments in which the map describes subsequent macro-diversity regions, the method of  FIG. 8  may be modified so that it collectively examines the impacts on both the prior and/or subsequent data frames when scheduling data bursts to a macro-diversity region. 
     Various implementations of the invention are realized in electronic hardware, computer software, or combinations of these technologies. Some implementations include one or more computer programs executed by one or more computing devices. In general, each computer includes one or more processors, one or more data-storage components (e.g., volatile or non-volatile memory modules and persistent optical and magnetic storage devices, such as hard and floppy disk drives, CD-ROM drives, and magnetic tape drives), one or more input devices (e.g., mice and keyboards), and one or more output devices (e.g., display consoles and printers). 
     The computer programs include executable code that is usually stored in a persistent storage medium and then copied into memory at run-time. At least one processor executes the code by retrieving program instructions from memory in a prescribed order. When executing the program code, the computer receives data from the input and/or storage devices, performs operations on the data, and then delivers the resulting data to the output and/or storage devices. 
     Various illustrative implementations of the present invention have been described. However, one of ordinary skill in the art will see that additional implementations are also possible and within the scope of the present invention. 
     Accordingly, the present invention is not limited to only those implementations described above. Those of skill in the art will appreciate that the various illustrative modules and method steps described in connection with the above described figures and the implementations disclosed herein can often be implemented as electronic hardware, software, firmware or combinations of the foregoing. To clearly illustrate this interchangeability of hardware and software, various illustrative modules and method steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled persons can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the invention. In addition, the grouping of functions within a module or step is for ease of description. Specific functions can be moved from one module or step to another without departing from the invention. 
     Moreover, the various illustrative modules and method steps described in connection with the implementations disclosed herein can be implemented or performed with a general purpose processor, a digital signal processor (“DSP”), an application specific integrated circuit (“ASIC”), a field programmable gate array (“FPGA”) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
     Additionally, the steps of a method or algorithm described in connection with the implementations disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium including a network storage medium. An exemplary storage medium can be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor. The processor and the storage medium can also reside in an ASIC. 
     The above description of the disclosed implementations is provided to enable any person skilled in the art to make or use the invention. Various modifications to these implementations will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other implementations without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent example implementations of the invention and are therefore representative of the subject matter which is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other implementations and that the scope of the present invention is accordingly limited by nothing other than the appended claims.