Abstract:
A method and a communication apparatus for deciding a transmitting region for an allocated transmitting burst in a frame of an orthogonal frequency division multiplex access (OFDMA) system are provided. The communication apparatus comprises a decoder and a processing unit. The decoder decodes an MAP message, which is related to the allocated transmitting burst, into a plurality of parameters. The processing unit assigns a plurality of burst regions in the frame according to the parameters and decides a transmitting region according to the burst regions.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application claims the benefit of Provisional Application Ser. No. 60/826,750 filed on Sep. 25, 2006. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method and a communication apparatus for deciding a transmitting region for an allocated transmitting burst in a frame of an orthogonal frequency division multiplex access (OFDMA) system according to a plurality of burst regions. 
   2. Descriptions of the Related Art 
   The use of broadband services has increased with the rapid development of computer networks. However, only computer users in some areas of the world can obtain high-speed wired broadband services, such as digital subscribe line (DSL), cable broadband accessing service, etc. While network telecommunication service providers would like to expand the availability range of their broadband networks, the high construction costs for building wired networks prevents them from doing so. Therefore, developing wireless broadband network technologies has become a viable alternative. Present wireless network technologies include wide area network (WAN), metropolitan area network (MAN), local area network (LAN), and personal area network (PAN). Each technology applies to its own communication distance. 
   The IEEE 802.16e, or WiMAX, is a new wireless transmission standard which was initially established for metropolitan area network to provide the “last mile” wireless broadband connection technology. After improvements, the IEEE 802.16e can also support other market needs, such as various mobile and high-speed broadband applications. In contrast with the IEEE 802.11 (Wi-Fi) and 3G mobile communication technology, the IEEE 802.16e has a greater network broadband, lower building costs, better service quality, and better expansibility. Furthermore, it can assist and expand on Wi-Fi hot points. 
   A conventional OFDMA wireless communication system  1  based on the IEEE 802.16e is illustrated in  FIG. 1 . The OFDMA wireless communication system  1  comprises a base station (BS)  101  and a plurality of mobile stations (MSs)  103 ,  105 ,  107 ,  109 . For brevity, the MSs will be denoted hereinafter as the first MS  103 , second MS  105 , third MS  107 , and fourth MS  109 . There are a plurality of frames used to transmit information and/or data between the BS  101  and the MSs  103 ˜ 109  in the OFDMA wireless communication system  1  as illustrated in  FIG. 2 . For brevity, the frames will be denoted hereinafter as frames  21 ,  23 ,  25 . The frames  21 ,  23 ,  25  are allocated by a wireless communication apparatus, such as the BS  101 . The x-axis in  FIG. 2  represents the symbol axis, while the y-axis represents the sub-channel axis. 
   The frames  21 ,  23 ,  25  of the OFDMA wireless communication system  1  respectively comprise downlink sub-frames  211 ,  231 ,  251  and uplink sub-frames  213 ,  233 ,  253 . Each of these sub-frames can be used for downlinking (BS to MSs) or uplinking (MSs to BS) information/data transmission to the OFDMA wireless communication system  1 . In addition, each of the downlink sub-frames  211 ,  231 ,  251  respectively comprise Uplink-MAPs  2111 ,  2311 ,  2511 , which are uplink bursts allocated by slots to different MSs  103 ˜ 109 . Each of the uplink sub-frames  213 ,  233 ,  253  respectively comprises some control regions, such as ranging sub-channel regions or fast feedback regions. 
   In more detail, the Uplink-MAP  2111  of the downlink sub-frame  211  will allocate the following: an uplink burst  2333  with slots of the first MS  103 , an uplink burst  2334  with slots of the second MS  105 , an uplink burst  2335  with slots of the third MS  107 , and an uplink burst  2336  with slots of the fourth MS  109 . These uplink bursts will be allocated in the uplink sub-frame  233  using different information elements (not shown), aside from the ranging sub-channel  2331  and the fast feedback  2332 . The information element of the first MS  103  in the Uplink-MAP  2111  allocates a sub-channel offset, a symbol offset, and a number of slots of the uplink burst  2333 , while the information element of the second MS  105  in the Uplink-MAP  2111  allocates a sub-channel offset, a symbol offset, and a number of slots of the uplink burst  2334 . Likewise, the information element of the third MS  107  in the Uplink-MAP  2111  allocates a sub-channel offset, a symbol offset, and a number of slots of the uplink burst  2335 ; while the information element of the fourth MS  109  in the Uplink-MAP  2111  allocates a sub-channel offset, a symbol offset, and a number of slots of the uplink burst  2336 . Finally, the uplink bursts  2333 ˜ 2336  of the uplink sub-frame  233  can be described by the above specification and can be respectively transmitted with the allocated slots by each baseband processor of the MSs  103 ˜ 109 . 
   In the same way, the Uplink-MAP  2311  of the downlink sub-frame  231  will allocate uplink bursts with slots of the MSs  103 ˜ 109  in the uplink sub-frame  253 , and the Uplink-MAP  2511  of the downlink sub-frame  251  will allocate uplink bursts with slots of the MSs  103 ˜ 109  in the uplink sub-frame of the next frame (not shown). 
   With the information elements described above, uplink bursts of the MSs  103 ˜ 109  will be allocated in each uplink sub-frame for transmitting information/data from the MSs  103 ˜ 109  to BS  101 . However, when the number of the MSs increases, the calculating time of allocating slots for each MS increases as well, thereby, reducing the transmitting efficiency of the OFDMA wireless communication system  1 . Accordingly, it is important for the mobile communication providers and the mobile communication apparatus manufacturers to find a solution for improving the calculation time of allocating slots for each MS to increase the transmitting efficiency of the wireless communication system. 
   SUMMARY OF THE INVENTION 
   One objective of this invention is to provide a method for deciding a transmitting region for an allocated transmitting burst in a frame of an OFDMA system. The method comprises the following steps: decoding an MAP message into a plurality of parameters, the MAP message relating to the allocated transmitting burst; assigning a first burst region in the frame according to the parameters; assigning a second burst region in the frame according to the parameters; and deciding the transmitting region according to the first burst region and the second burst region. 
   Another objective of this invention is to provide a communication apparatus for deciding a transmitting region for an allocated transmitting burst in a frame of an OFDMA system. The communication apparatus comprises a decoder and a processing unit. The decoder decodes an MAP message into a plurality of parameters and the MAP message relates to the allocated transmitting burst. The processing unit assigns a first burst region and a second burst region in the frame according to the parameters, and decides the transmitting region according to the first and second burst regions. 
   Another objective of this invention is to provide a method for deciding the transmitting region for an allocated transmitting burst in the frame of an OFDMA system. The method comprises the following steps: decoding the MAP message, which is related to the allocated transmitting burst, into a plurality of parameters; determining one or more necessary burst regions according to the parameters; and deciding the transmitting region by merging one or more necessary burst regions. The MAP message is used to indicate the slot allocations for at least one of the mobile stations in an uplink sub-frame and is stored in a downlink sub-frame. The plurality of parameters comprises a first slot location, a number of allocated slots, and an uplink sub-frame symbol duration of the transmitting region. Each of the necessary burst regions comprises a symbol offset, a sub-channel offset, a number of symbols, and a number of sub-channels according to the parameters. 
   A further objective of this invention is to provide a method for deciding a transmitting region for an allocated transmitting burst in a frame of an OFDMA system. The method comprises the following steps: decoding the MAP message, which is related to the allocated transmitting burst, into a plurality of parameters; determining a desired burst region according to the parameters; determining one or more unnecessary burst regions according to the parameters; and deciding the transmitting region by subtracting one or more unnecessary burst regions from the desired burst region. The MAP message indicates the slot allocations for at least one of the mobile stations in an uplink sub-frame and is stored in a downlink sub-frame. The plurality of parameters comprises a first slot location, a number of allocated slots, and an uplink sub-frame symbol of the transmitting region. Each unnecessary burst regions comprises a symbol offset, a sub-channel offset, a number of symbols, and a number of sub-channels according to the parameters. 
   By satisfying these objectives, the present invention determines a transmitting region of an MS with allocated slots in a frame according to a plurality of burst regions. Accordingly, the calculation time of the allocating slots for each MS can be improved so that the transmitting efficiency of the wireless communication system can be increased. 
   The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in the art to well appreciate the features of the claimed invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram illustrating a conventional OFDMA wireless communication system based on the IEEE 802.16e; 
       FIG. 2  is a schematic diagram illustrating a plurality of frames used to transmit information and/or data in the conventional OFDMA wireless communication system; 
       FIG. 3  is a schematic diagram illustrating a communication apparatus of a first embodiment of the present invention; 
       FIG. 4  is a schematic diagram illustrating a plurality of frames used to transmit information and/or data in the OFDMA wireless communication system of the first embodiment; 
       FIG. 5  is a schematic diagram illustrating another plurality of frames used to transmit information and/or data in the OFDMA wireless communication system of the first embodiment; 
       FIG. 6  is a flow chart of a second embodiment of the present invention; and 
       FIG. 7  is a flow chart of a third embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The IEEE 802.16e standard is a standard that is based on the IEEE 802.16 standard and that further comprises an OFDMA wireless communication system of the present invention. 
   A first embodiment of the present invention is a communication apparatus for deciding a transmitting region for an allocated transmitting burst in a frame of an OFDMA wireless communication system. The OFDMA wireless communication system  1  is illustrated in FIG.  1 , which comprises a BS  101  and a plurality of MSs  103 ,  105 ,  107 ,  109 . For brevity, the MSs will be denoted hereinafter as the first MS  103 , second MS  105 , third MS  107 , and fourth MS  109 . As illustrated in  FIG. 3 , the communication apparatus  3 , such as the MS  105 , comprises a receiving module  31 , a decoder  33 , a processing unit  35 , and a baseband processor  37 . There are a plurality of frames used to transmit information and/or data between the BS  101  and the MSs  103 ˜ 109  in the OFDMA wireless communication system  1  as illustrated in  FIG. 4 . For brevity, the frames will be denoted hereinafter as the frames  41 ,  43 . The frames  41 ,  43  are allocated by a wireless communication apparatus, such as the BS  101 . The x-axis in  FIG. 4  represents the symbol axis, while the y-axis represents the sub-channel axis. 
   The frames  41 ,  43  of the OFDMA wireless communication system  1  respectively comprise downlink sub-frames  411 ,  431  and uplink sub-frames  413 ,  433 . Each of these sub-frames can be used for downlink (BS to MSs) or uplink (MSs to BS) information/data transmission in the OFDMA wireless communication system  1 . In addition, each of the downlink sub-frames  411 ,  431  respectively Uplink-MAPs  4111 ,  4311  to describe uplink bursts which are allocated by the slots of different MSs  103 ˜ 109 . Each of the uplink sub-frames  413 ,  433  respectively comprises some control regions, such as the ranging sub-channel region  4331  or fast feedback region  4332 . 
   After the MS  105  receives the frame  41 , the receiving module  31  transmits the Uplink-MAP  4111  to the decoder  33 . The decoder  33  decodes the Uplink-MAP  4111  into a plurality of parameters and transmits the slots that allocate information, including the first slot location, the number of allocated slots and the uplink sub-frame symbol duration, of the transmitting region into the uplink sub-frame  433 . Then, the decoder  33  transmits the parameters and slots allocation information to the processing unit  35 . 
   In one case, the transmitting region with slots of the MS  105  is described by three burst regions  4333 ,  4334 ,  4335 . The processing unit  35  decides the first symbol offset, first sub-channel offset, first number of symbols, and first number of sub-channels to assign the first burst region  4333 . In addition, the processing unit  35  also decides the second symbol offset, second sub-channel offset, second number of symbols, and second number of sub-channels to assign the second burst region  4334 . The processing unit  35  decides the third symbol offset, third sub-channel offset, third number of symbols, and third number of sub-channels to assign the third burst region  4335 . Finally, the processing unit  35  decides the transmitting region by merging the first burst region  4333 , second burst region  4334 , and third burst region  4335 . The baseband processor  37  uses the transmitting region of the MS  105  to transmit information/data from the MS  105  to the BS  101  after receiving the transmitting region. 
   In another case of the first embodiment, there are a plurality of frames used to transmit information and/or data between the BS  101  and the MSs  103 ˜ 109  in the OFDMA wireless communication system  1  as illustrated in  FIG. 5 . For brevity, the frames will be denoted hereinafter as the frames  51 ,  53 . The frames  51 ,  53  are allocated by a wireless communication apparatus, such as the BS  101 . The x-axis in  FIG. 5  represents the symbol axis, while the y-axis represents the sub-channel axis. 
   The frames  51 ,  53  of the OFDMA wireless communication system  1  respectively comprise downlink sub-frames  511 ,  531  and uplink sub-frames  513 ,  533 . Each of these sub-frames can be used for downlink (BS to MSs) or uplink (MSs to BS) information/data transmission in the OFDMA wireless communication system  1 . In addition, each of the downlink sub-frames  511 ,  531  respectively comprise Uplink-MAPs  5111 ,  5311  to describe uplink bursts, which are allocated by slots, to different MSs  103 ˜ 109 . Each of the uplink sub-frames  513 ,  533  respectively comprises some control regions, such as a ranging sub-channel region  5331  or fast feedback region  5332 . 
   For example, the transmitting region with slots of the MS  105  is described by three burst regions  5333 ,  5334 ,  5335 . The processing unit  35  decides the desired symbol offset, desired sub-channel offset, desired number of symbols, and desired number of sub-channels to assign the desired burst region  5333 . In addition, the processing unit  35  also decides the first symbol offset, first sub-channel offset, first number of symbols, and first number of sub-channels to assign the first burst region  5334 . Then, the processing unit  35  decides the second symbol offset, second sub-channel offset, second number of symbols, and second number of sub-channels to assign the second burst region  5335 . Finally, the processing unit  35  decides the transmitting region by subtracting the first burst region  5334  and the second burst region  5335  from the desired burst region  5333 . The baseband processor  37  uses the transmitting region of the MS  105  to transmit information/data from the MS  105  to the BS  101  after receiving the transmitting region. 
   Even though the transmitting region of the MS  105  can be decided by subtracting the first burst region  5334  and the second burst region  5335  from the desired burst region  5333 , if one of the control regions covers the desired burst region  5333 , the transmitting region of the MS  105  is decided by further subtracting one of the covered control regions from the desired burst region  5333 . Those skilled in the art can understand the corresponding operations of the subtracting by looking at the above description; thus, no unnecessary detail is given. 
   A second embodiment of the invention provides a method for deciding a transmitting region for an allocated transmitting burst in a frame of an OFDMA wireless communication system. The method applied to a communication apparatus, such as the MS  105 , is as described in the first embodiment. The corresponding flow chart is shown in  FIG. 6 . 
   First, step  601  is executed for decoding an MAP message into a plurality of parameters, wherein the MAP message relates to the allocated transmitting burst. Next, step  603  is executed for determining one or more necessary burst regions according to the parameters. Finally, step  605  is executed for deciding the transmitting region by merging one or more necessary burst regions. 
   In addition to the steps shown in  FIG. 6 , the second embodiment can also execute all the operations of the first embodiment. Those skilled in the art can understand the corresponding steps and operations of the second embodiment by looking at those in the first embodiment; thus, no unnecessary detail is given. 
   A third embodiment of the invention provides a method for deciding a transmitting region for an allocated transmitting burst in a frame of an OFDMA wireless communication system. The method applied to a communication apparatus, such as the MS  105 , is as described in the first embodiment. The corresponding flow chart is shown in  FIG. 7 . 
   First, step  701  is executed for decoding an MAP message into a plurality of parameters, wherein the MAP message relates to the allocated transmitting burst. Next, step  703  is executed for determining a desired burst region according to the parameters. Then, step  705  is executed for determining one or more unnecessary burst regions according to the parameters. Finally, step  707  is executed for deciding the transmitting region by subtracting one or more unnecessary burst regions from the desired burst region. 
   In addition to the steps shown in  FIG. 7 , the third embodiment can also execute all the operations of the first embodiment. Those skilled in the art can understand the corresponding steps and operations of the third embodiment by looking at those in the first embodiment; thus, no unnecessary detail is given. 
   According to the aforementioned descriptions, the present invention provides a new method for deciding a transmitting region with allocated slots of an MS in a frame according to a plurality of burst regions. The burst regions can be merged or subtracted from each other to decide the transmitting region. Accordingly, the calculation time of allocating slots for each MS can be improved so that the transmitting efficiency of the wireless communication system can be increased. 
   The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in the art may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.