Abstract:
A method for transmitting common control information from a Base Station (BS) to an Mobile Station (MS) in a wireless mobile communication system is provided, in which the BS generates a MAP Information Element (IE) using common control information to be transmitted to the MS, the common control information being resource allocation information and control information, converts the MAP IE to a MAP IE message, applies an Modulation and Coding Scheme (MCS) level corresponding to the channel status of the MS, and transmits the MAP IE message with data to the MS.

Description:
PRIORITY 
       [0001]    This application claims priority under 35 U.S.C. §119(a) to a Korean Patent Application filed in the Korean Intellectual Property Office on Jun. 9, 2006 and assigned Serial No. 2006-51920, the entire disclosure of which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to a method for managing resources in a wireless mobile communication system. More particularly, the present invention relates to a method for transmitting common control information in a wireless mobile communication system. 
         [0004]    2. Description of the Related Art 
         [0005]    Providing services with diverse Quality of Service (QoS) requirements at or above 100 Mbps to users is an active study area for a future-generation communication system, known as a 4th Generation (4G) communication system. Particularly, active research is conducted on providing high-speed service by ensuring mobility and QoS to a Broadband Wireless Access (BWA) communication system such as Wireless Local Area Network (WLAN) and Wireless Metropolitan Area Network (WMAN). A major example of such a system is an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system. 
         [0006]      FIG. 1  illustrates a configuration of a typical IEEE 802.16 communication system. The IEEE 802.16 communication system ensures a mobility of Subscriber Stations (SSs) and thus it is deployed in a multi-cell structure. Such cells as illustrated in  FIG. 1  are neighboring to one another in the IEEE 802.16 communication system. 
         [0007]    Referring to  FIG. 1 , the communication system includes a Base Station (BS)  101  that covers a cell  100  and a plurality of Mobile Stations (MSs)  103 ,  105 ,  107 ,  109 , and  111  (referred to as MS 1  to MS 5 , respectively) that receive a communication service from the BS  101 . Signaling can be carried out in Orthogonal Frequency Division Multiplexing (OFDM)/Orthogonal Frequency Division Multiple Access (OFDMA) between the BS 101  and MS 1  to MSS. 
         [0008]    In the wireless mobile communication system, data is transmitted in frames, each being divided into a MAP area with control information and resource allocation information, a DownLink (DL) burst area, and an UpLink (UL) burst area. The BS transmits the resource allocation information to the MSs by MAP messages, DL-MAP and UL-MAP. The DL-MAP message and the UL-MAP message have the following configurations described in Table 1 and Table 2 below, respectively: 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Syntax 
                 Size (bits) 
                 Notes 
               
               
                   
               
             
             
               
                 DL-MAP_Message_Format( ) { 
                   
                   
               
               
                  Management Message Type=2 
                 8 
               
               
                  PHY Synchronization Field 
                 Variable 
                 See appropriate PHY 
               
               
                   
                   
                 specification 
               
               
                  DCD Count 
                 8 
               
               
                  Base Station ID 
                 48  
               
               
                  Begin PHY Specific Section { 
                   
                 See applicable PHY 
               
               
                   
                   
                 subclause 
               
               
                   if (Wireless MAN-OFDMA) { 
               
               
                    No. OFDMA symbols 
                 8 
                 Number of OFDMA 
               
               
                   
                   
                 symbols in the DL 
               
               
                   
                   
                 subframe including all 
               
               
                   
                   
                 AAS/permutation zone 
               
               
                    } 
               
               
                    for (i=1;i&lt;=n;i++) { 
                   
                 For each DL-MAP 
               
               
                   
                   
                 element 1 to n 
               
               
                     DL-MAP_IE( ) 
                 variable 
                 See corresponding PHY 
               
               
                   
                   
                 specification 
               
               
                    } 
               
               
                   } 
               
               
                   if ! (byte boundary) { 
               
               
                    Padding Nibble 
                 4 
                 Padding to reach byte 
               
               
                   
                   
                 boundary 
               
               
                   } 
               
               
                  } 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Syntax 
                 Size (bits) 
                 Notes 
               
               
                   
               
             
             
               
                 UL-MAP_Message_Format( ) { 
                   
                   
               
               
                  Management Message Type=3 
                 8 
               
               
                  Reserved 
                 8 
                 Shall be set to zero 
               
               
                  UCD Count 
                 8 
               
               
                  Allocation Start Time 
                 32  
               
               
                  Begin PHY Specific Section { 
                   
                 See applicaple PHY 
               
               
                   
                   
                 subclause 
               
               
                   if (Wireless MAN-OFDMA) { 
               
               
                    No. OFDMA symbols 
                 8 
                 Number of OFDMA 
               
               
                   
                   
                 symbols in 
               
               
                   
                   
                 the UL subframe 
               
               
                    } 
               
               
                    for (i=1;i&lt;=n;i++) { 
                   
                 For each UL-MAP 
               
               
                   
                   
                 element 1 to n 
               
               
                     UL-MAP_IE( ) 
                 variable 
                 See corresponding PHY 
               
               
                   
                   
                 specification 
               
               
                    } 
               
               
                   } 
               
               
                   if ! (byte boundary) { 
               
               
                    Padding Nibble 
                 4 
                 Padding to reach byte 
               
               
                   
                   
                 boundary 
               
               
                   } 
               
               
                  } 
               
               
                   
               
             
          
         
       
     
         [0009]    The BS transmits DL and UL resource allocation information by the DL-MAP and UL-MAP messages. The MSs detect control information and information about the locations of resources allocated to them by decoding the DL-MAP and UL-MAP messages. Thus, the. MSs are capable of transmitting/receiving DL or UL data using the detected information. 
         [0010]    During data transmission/reception, the MSs are placed in different channel statuses, i.e. different propagation environments due to obstacles or propagation interference between the BS and the MSs. Therefore, the BS adaptively selects a Modulation and Coding Scheme (MCS) level for each of the MSs, according to the channel status of the MS. 
         [0011]    MCS levels are combinations of modulation and coding, and range from level  1  to level N according to the number of available MCSs. MCS levels are adaptively selected according to the channel statuses between the BS and the MSs. In case of a good channel status between the BS and an MS, the BS may select a high MCS level specifying 64-ary Quadrature Amplitude Modulation (64 QAM) and a code rate 5/6 for the MS. In case of a poor channel status between the BS and the MS, the BS may select a low MCS level specifying Quadrature Phase Shift Keying (QPSK) and a code rate 1/12 for the MS. 
         [0012]    Assuming MS 1   103  is in the best channel status and MS 5   111  is in the poorest channel status in  FIG. 1 , the BS  101  selects MCS levels based on channel status information received from MS 1   103  and MS 5   111  and transmits data encoded and modulated using the selected MCS levels to MS 1   103  and MS 5   111 . MS 1   103  and MS 5   111  have different resource requirements according to their channel statuses. Hence, the BS  101  allocates required resources to them through MCS level selection. In general, the least resources are allocated to the MS in the best channel status and the most resources to the MS in the poorest channel status. 
         [0013]    MAP information including system information and resource allocation information is so significant that MSs must receive the, MAP information. That&#39;s why the BS  101  transmits the MAP information using the most robust MCS level. For the same amount of information, a lower MCS level requires a larger amount of resources. That is, the MAP information requires the same or more resources in amount, compared to data transmitted to each MS. However, every MS may not need receive the MAP information because a certain MAP IE is destined for a particular MS or some MSs. Consequently, use of a large amount of radio resources for the MAP IE (Information Element) decreases radio resource utilization. 
       SUMMARY OF THE INVENTION 
       [0014]    An aspect of the present invention is to address at least the problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of exemplary embodiments of the present invention is to provide a method for efficiently managing radio resources in a wireless mobile communication system. 
         [0015]    In accordance with an aspect of the present invention, there is provided a method for transmitting common control information to an MS in a BS in a wireless mobile communication system, in which the BS generates a MAP IE using common control information to be transmitted to the MS, the common control information being resource allocation information and control information, converts the MAP IE to a MAP IE message, applies an MCS level corresponding to the channel status of the MS, and transmits the MAP IE message with data to the MS. 
         [0016]    In accordance with another aspect of the present invention, there is provided a method for receiving common control information from a BS in an MS in a wireless mobile communication system, in which the MS receives a data burst IE associated with data burst allocation from the BS, decodes a data burst using the data burst IE, and detects a MAP IE message including common control information during the decoding, the common control information being resource allocation information and control information. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The above and other objects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0018]      FIG. 1  illustrates the configuration of a typical IEEE 802.16 communication system; 
           [0019]      FIG. 2  illustrates the format of a Medium Access Control (MAC) management message in a wireless mobile communication system according to the present invention; 
           [0020]      FIG. 3  is a flowchart illustrating a MAP IE transmission operation in a BS according to the present invention; 
           [0021]      FIG. 4  is a flowchart illustrating a MAP IE reception operation in an MS according to present invention; and 
           [0022]      FIGS. 5A and 5B  illustrate exemplary data burst structures and MAP IEs according to the present invention. 
       
    
    
       [0023]    Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features and structures. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0024]    The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of exemplary embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
         [0025]    The present invention discloses a method for transmitting MAP information in the form of a message in a wireless mobile communication system. This message is a MAC (Medium Access Control) management message. Transmission of the MAP information in the form of the message requires fewer resources than transmission of the MAP information in a MAP area because the BS converts the MAP information to the message prior to transmission under the assumption that it already has knowledge of the channel status of the MS. The MAP information includes control information and resource allocation information and will be referred to as common control information hereinbelow. 
         [0026]    The present invention is applicable to any wireless mobile communication system using a DL-MAP IE and a UL-MAP IE. 
         [0027]      FIG. 2  illustrates the format of a MAC management message in a wireless mobile communication system according to the present invention. 
         [0028]    Referring to  FIG. 2 , a BS exchanges information with an MS through MAC management messages. The MAC management messages each include a 6-byte Generic MAC Header field  210 , a 1-byte Management Message Type field  220 , a variable-length Management Message Payload  230  field, and a 4-byte Cyclic Redundancy Check (CRC) field  240 . 
         [0029]    The Generic MAC Header field  210  is composed of a Header Type (HT) field, an Encryption Control (EC) field indicating whether data is encrypted, a Type field indicating whether a subheader exists, a CI (CRC Indicator) field indicating the presence or absence of the CRC field, an Encryption Key Sequence (EKS) field, a Length field indicating the total length of the MAC management message, a Connection IDentifier (CID) field, and a Header Check Sequence (HCS) field for use in checking link errors of the Generic MAC Header  210 . 
         [0030]    The Management Message Type field  220  contains an ID identifying the usage of a new DL-MAP IE/UL-MAP IE message proposed according to the present invention. These new DL-MAP IE and UL-MAP IE messages are defined in Table 3 below. 
         [0000]    
       
         
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                 Message 
                   
               
               
                 Type 
                 Message Name 
                 Description 
                 Connection 
               
               
                   
               
             
             
               
                 TBD (To Be 
                 DL-MAP IE 
                 Downlink Access 
                 Broadcasting or 
               
               
                 Determined) 
                 Message 
                 Definition 
                 Basic CID 
               
               
                 TBD 
                 UL-MAP IE 
                 Uplink Access 
                 Broadcasting or 
               
               
                   
                 Message 
                 Definition 
                 Basic CID 
               
               
                   
               
             
          
         
       
     
         [0031]    Unlike the conventional MAP information transmission in the MAP area, the DL-MAP IE message and the UL-MAP IE message described in Table 3 are transmitted along with DL data in the present invention. If the DL-MAP IE message and the UL-MAP IE message are directed to one MS, they can be transmitted using a basic CID specific to the MS. 
         [0032]    Table 4 and Table 5 illustrate the formats of the DL-MAP IE message and the UL-MAP IE message, respectively. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 Syntax 
                 Size (bits) 
                 Notes 
               
               
                   
               
             
             
               
                 DL-MAP-IE_Message_Format( ) 
                   
                   
               
               
                 { 
               
               
                  Management Message 
                 8 
               
               
                 Type=?? 
               
               
                  for (i=1;i&lt;=n;i++) { 
                   
                 For each DL-MAP 
               
               
                   
                   
                 element 1 to n 
               
               
                    DL-MAP_IE( ) 
                 variable 
                 See corresponding PHY 
               
               
                   
                   
                 specification 
               
               
                  } 
               
               
                  if ! (byte boundary) { 
               
               
                   Padding Nibble 
                 4 
                 Padding to reach byte 
               
               
                   
                   
                 boundary 
               
               
                  } 
               
               
                 } 
               
               
                   
               
             
          
         
       
     
         [0033]    Preferably but not necessarily, the length in bytes of the DL-MAP IE message is an integer. If the DL-MAP IE message does not have an integer number of bytes, some bits must be padded in the message and the MS must neglect the padding. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 5 
               
               
                   
               
               
                 Syntax 
                 Size (bits) 
                 Notes 
               
               
                   
               
             
             
               
                 UL-MAP-IE_Message_Format( ) 
                   
                   
               
               
                 { 
               
               
                  Management Message 
                 8 
               
               
                 Type=?? 
               
               
                  for (i=1;i&lt;=n;i++) { 
                   
                 For each UL-MAP 
               
               
                   
                   
                 element 1 to n 
               
               
                  UL-MAP_IE( ) 
                 variable 
                 See corresponding PHY 
               
               
                   
                   
                 specification 
               
               
                  } 
               
               
                  if ! (byte boundary) { 
               
               
                   Padding Nibble 
                 4 
                 Padding to reach byte 
               
               
                   
                   
                 boundary 
               
               
                  } 
               
               
                 } 
               
               
                   
               
             
          
         
       
     
         [0034]    As with the UL-MAP IE message, preferably but not necessarily, the length in bytes of the UL-MAP IE message is an integer. If the UL-MAP IE message does not have an integer number of bytes, some bits must be padded in the message and the MS must neglect the padding. 
         [0035]    When transmitting a particular UL burst IE in the UL-MAP IE message, the BS must notify the MS of the absolute position of the UL burst IE in a UL burst area. It is because the MS cannot receive every UL burst IE in a frame, which means that the MS cannot determine the accurate position of the UL burst IE. 
         [0036]      FIG. 3  is a flowchart illustrating a MAP IE transmission operation in a BS according to the present invention. 
         [0037]    Referring to  FIG. 3 , the BS generates a MAP IE in step  302 . The MAP IE is a DL-MAP IE or a UL-MAP IE and can be directed to one or more MSs. In step  304 , the BS determines an MS to receive the MAP IE, selects an MCS level according to the channel status of the MS, and applies the MCS level to the MAP IE. 
         [0038]    In step  306 , the BS compares the MCS level of the MAP IE with a predetermined MCS level threshold. If the MCS level of the MAP IE is less than or equal to the MCS level threshold, the BS goes to step  308 . If the MCS level of the MAP IE is greater than the MCS level threshold, the BS proceeds to step  310 . 
         [0039]    In step  308 , the BS transmits the MAP IE in the MAP area to the MS. In step  310 , the BS converts the MAP IE to a message and transmits the message to the MS. 
         [0040]      FIG. 4  is a flowchart illustrating a MAP IE reception operation in an MS according to the present invention. 
         [0041]    Referring to  FIG. 4 , the MS separates at least one MAP IE from a MAP message received from the BS in step  402 . The MAP message is a DLFUL-MAP message or a compressed MAP message with the DL-MAP message and the UL-MAP message in combination. The MAP message may contain at least one MAP IE. In step  404 , the MS determines whether it is supposed to receive and process the MAP IE by checking a CID included in the MAP IE. If the CID of the MS is present in the MAP IE, the MS receives and processes the MAP IE. If a broadcasting CID exists instead of the CID in the MAP IE, which means that the MAP IE is directed to all MSs, the MS receives and processes the MAP IE. In this manner, the MS detects a MAP IE to receive and process referring to a CID in the MAP IE. Meanwhile, if the MS determines that it is not supposed to receive and process the MAP IE, it discards the MAP IE in step  406 . 
         [0042]    In step  408 , the MS determines whether the MAP IE to receive and process is a DL burst IE associated with data burst allocation. If the MAP IE is a DL burst IE, the MS goes to step  412 . If the MAP IE is not a DL burst IE, the MS processes the MAP IE in step  410 . The MS decodes a data burst indicated by the DL burst IE in step  412  and determines whether the data burst includes a MAP IE message proposed by the present invention, i.e. a DL-MAP IE message or a UL-MAP IE message in step  414 . To make this determination, the MS checks the CID field of the Generic MAC Header  210  of the MAP IE message. For example, if a broadcasting CID or the ID of the MS is filled in the CID field, the MS processes the MAP IE message. In the presence of the MAP IE message for the MS, the MS returns to step  408  and otherwise, it ends the algorithm of the present invention. 
         [0043]      FIGS. 5A and 5B  illustrate exemplary data burst structures and MAP IEs according to the present invention. 
         [0044]    The BS selects a MAP IE from among a plurality of MAP IEs, for transmission along with a data burst, converts the MAP IE in the form of a message, and transmits the MAP IE message to the MS. Therefore, the same MCS level is applied to both the MAP IE message and the data burst. 
         [0045]    Referring to  FIG. 5A , a first DL burst  501  (DL burst # 1 ) is for MS 1  but includes a DL-MAP IE message with a DL burst IE for MS 2 . A second DL burst  503  (DL burst # 2 ) is for MS 2  and includes a DL-MAP IE message with an UL-Burst_IE and a Power_Control_IE for MS 2 . 
         [0046]    A third DL burst  505  (DL burst # 3 ) is for MS 3 . DL burst # 3   505  includes a DL-MAP IE message with a Channel_Measurement IE for MS 3  and a UL-MAP IE message with a Channel Quality Information CHannel (CQICH)_Alloc_IE for MS 3 . 
         [0047]      FIG. 5B  illustrates DL-MAP TEs and UL-MAP IEs. Conventionally, all IEs are transmitted in the MAP areas. Thus, a Channel_Measurement IE  507 , a DL burst IE for DL burst # 1   509 , a CID_Switch_IE  511 , a DL burst IE for DL burst # 2   513 , a CQICH_Alloc_IE  515 , a Power_Control_IE  517 , a UL burst IE for UL burst # 1   519 , and a UL burst IE for UL burst # 2   521  are included in MAP messages. 
         [0048]    However, in accordance with the present invention, some TEs  507 ,  513 ,  515 ,  517  and  521  are converted to MAC management messages and transmitted in data bursts, as illustrated in  FIG. 5A . Therefore, radio resources are efficiently utilized. 
         [0049]    For example, MSs decode a DL-MAP message and acquire allocation information about DL burst # 1   501 . It is assumed herein that DL burst # 1   501  is directed to all MSs. Hence, MS 2  decodes DL burst # 1   501  and is aware that DL burst # 1   501  includes a DL-MAP IE message for MS 2 . Thus, MS 2  acquires information with which to decode DL burst # 2   503  using the DL-MAP IE message. 
         [0050]    MS 2  decodes DL burst # 2   503  and recognizes that it includes a UL-MAP IE message with a Power_Control_IE  517 . MS 2  then processes the UL-MAP IE message so as to transmit a UL burst and changes uplink power as indicated by the Power_Control_IE  517 . 
         [0051]    In the same manner, MS 3  processes the DL-MAP message or a DL-MAP IE message included in a data burst. Thus, MS 3  decodes DL burst # 3   505  and is aware that the DL burst # 3   505  includes a DL-MAP IE message with a Channel_Measurement_IE and a UL-MAP IE message with a CQICH_Alloc_IE. Thus, MS 3  reports a channel measurement to the BS on a feedback channel indicated by the Channel_Measurement_IE. 
         [0052]    In accordance with the present invention as described above, a BS converts MAP IEs to MAC IE messages and transmits them in data bursts, compared to conventional transmission of the MAP IEs in a MAP area. Therefore, while the lowest MCS level is applied to the MAP IEs in the conventional technology, the MAP IE messages are encoded and modulated using MCS levels that are selected according to the channel statuses of MSs. Consequently, radio resources are saved. 
         [0053]    While the invention has been shown and described with reference to certain exemplary embodiments of the present invention thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents.