Abstract:
An apparatus and a method are disclosed for allocating a connection identifier by a base station in a communication system. The method includes: checking if a mobile station can use a private connection identifier; allocating at least one private connection identifier to the mobile station when the mobile station can use the private connection identifier, wherein the private connection identifier can be allocated to multiple mobile stations controlled by the base station, and at least two private connection identifiers allocated to each mobile station are not different from each other.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY 
       [0001]    This application claims the priority under 35 U.S.C. §119(a) of an application filed in the Korean Industrial Property Office on Jun. 1, 2007 and assigned Serial No. 2007-54111, the contents of which are hereby incorporated by reference. 
       TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention relates to a communication system, and more particularly to an apparatus and a method for allocating a connection identifier in a communication system. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the current communication systems, active research is in progress in order to provide users with high-speed services having various Qualities of Service (QoS). Especially, in the current next generation communication systems, active research is in progress in order to guarantee mobility and QoS for Broadband Wireless Access (BWA) communication systems. 
         [0004]    In order to communicate with a Base Station (BS) in such a communication system, a Mobile Station (MS) should establish a connection with the Base Station (BS). The MS is allocated a Connection Identifier (CID) from the BS. The CID is used for identification of the connection between the MS and the BS. The MS is allocated a primary management CID and a basic CID used for transmission/reception of a control signal from the BS, at the time of initial connection to the network. Further, for transmission/reception of user data, the MS is allocated a transport CID. 
         [0005]    In general, the CID allocated to the MS by the BS has a unique value within one BS. Further, when the MS moves from the service area of the BS to a service area of another BS, the MS should be allocated a new CID from the new BS. 
         [0006]    Table 1 below shows typical CIDs used in a communication system. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 CID 
                 Value 
                 Description 
               
               
                   
               
             
             
               
                 Ranging CID 
                 0x0000 
                 Used by SS and BS during ranging process. 
               
               
                 Basic CID 
                 0x0001-m 
                 The same value is assigned to both the DL and 
               
               
                   
                   
                 UL connection. 
               
               
                 Primary 
                 m + 1-2m 
                 The same value is assigned to both the DL and 
               
               
                 management 
                   
                 UL connection. 
               
               
                 Transport CIDs, 
                 2m + 1-FE9F 
                 For the secondary management connection, the 
               
               
                 Secondary Mgt 
                   
                 same value is assigned to both the DL and UL 
               
               
                 CIDs 
                   
                 connection. 
               
               
                 Multicast CIDs 
                 0xFEA0-0xFEFE 
                 For the downlink multicast service, the same 
               
               
                   
                   
                 value is assigned to all MSs on the same channel 
               
               
                   
                   
                 that participate in this connection. 
               
               
                 AAS initial 
                 0xFEFF 
                 A BS supporting AAS shall use this CID when 
               
               
                 ranging CID 
                   
                 allocating an AAS Ranging period (using AAS 
               
               
                   
                   
                 Ranging Allocation IE). 
               
               
                 Multicast 
                 0xFF00-0xFFF9 
                 A BS may be included in one or more multicast 
               
               
                 polling CIDs 
                   
                 polling groups for the purposes of obtaining 
               
               
                   
                   
                 bandwidth via polling. These connections have 
               
               
                   
                   
                 no associated service flow. 
               
               
                 Normal mode 
                 0xFFFA 
                 Used in DL-MAP to denote bursts for transmission 
               
               
                 multicast CID 
                   
                 of DL broadcast information to normal mode MS. 
               
               
                 Sleep mode 
                 0xFFFB 
                 Used in DL-MAP to denote bursts for transmission 
               
               
                 multicast CID 
                   
                 of DL broadcast information to Sleep mode MS. 
               
               
                   
                   
                 May also be used in MOB_TRE-IND messages. 
               
               
                 Idle mode 
                 0xFFFC 
                 Used in DL-MAP to denote bursts for transmission 
               
               
                 multicast CID 
                   
                 of DL broadcast information to Idle mode MS. 
               
               
                   
                   
                 May also be used in MOB_PAG-ADV message. 
               
               
                 Fragmentable 
                 0xFFFD 
                 Used by the BS for transmission of management 
               
               
                 Broadcast CID 
                   
                 broadcast information with fragmentation. The 
               
               
                   
                   
                 fragment sub header shall use 11-bit long FSN 
               
               
                   
                   
                 on this connection. 
               
               
                 Padding CID 
                 0xFFFE 
                 Used for transmission of padding information 
               
               
                   
                   
                 by SS and BS. 
               
               
                 Broadcasting CID 
                 0xFFFF 
                 Used for broadcast information that is 
               
               
                   
                   
                 transmitted on a downlink to all SS. 
               
               
                   
               
             
          
         
       
     
         [0007]    In relation to each of the basic CID, the primary management CID, and the transport CID, when an MS moves to a service area of a new BS (target BS) through handover, the CID of the MS may interfere with a CID of another MS belonging to the target BS. At this time, the target BS should allocate new CIDs to the MS. 
         [0008]    As described above, the target BS performs transport CID update according to movement of the MS. To this end, the target BS transmits transport CID update Type-Length-Value (TLV) to the MS. 
         [0009]    The BS should transmitmay bytes of TLV to the MS in order to update one CID and during the handover, it can cause delay to update the CID newly. 
       SUMMARY OF THE INVENTION 
       [0010]    As described above, the BS may need to update a CID of an MS due to some reasons, such as handover. Such an update requires consumption of as much resources as the number of the connections of the MS. 
         [0011]    Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and the present invention provides an apparatus and a method for allocating a connection identifier in a communication system. 
         [0012]    Also, the present invention provides an apparatus and a method for connection identifier update without wasting resources. 
         [0013]    Furthermore, the present invention provides an apparatus and a method for allocating a connection identifier according to movement of a mobile station in a communication system. 
         [0014]    Moreover, the present invention provides an apparatus and a method for allocating a connection identifier with a minimum quantity of resources consumed for update of the connection identifier in a communication system. 
         [0015]    In accordance with an aspect of the present invention, there is provided a method of allocating a connection identifier by a base station in a communication system, the method including the steps of: checking if a mobile station can use a private connection identifier; and allocating at least one private connection identifier to the mobile station when the mobile station can use the private connection identifier, wherein the private connection identifier can be repeatedly allocated to multiple mobile stations controlled by the base station, and at least two private connection identifiers allocated to each mobile station are not different from each other. In accordance with another aspect of the present invention, there is provided a method of being allocating a connection identifier by a mobile station in a communication system, the method including the steps of: informing a Base station if a mobile station can use a private connection identifier; receiving the private connection identifier from the base station, wherein the private connection identifier can be repeatedly allocated to multiple mobile stations controlled by the base station, and at least two private connection identifiers allocated to each mobile station are not different from each other. 
         [0016]    In accordance with another aspect of the present invention, there is provided an apparatus for allocating a connection identifier in a communication system, the apparatus including: a mobile station; and a base station for checking if the mobile station can use a private connection identifier, and allocating at least one private connection identifier to the mobile station when the message indicates that the mobile station can use the private connection identifier, wherein the private connection identifier can be allocated to multiple mobile stations controlled by the base station, and at least two private connection identifiers allocated to each mobile station are not different each other. 
         [0017]    Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior uses, as well as future uses of such defined words and phrases. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts: 
           [0019]      FIG. 1  illustrates allocation of a private transport CID in a communication system according to an embodiment of the present invention; 
           [0020]      FIG. 2  is a signal flow diagram illustrating allocation of a private transport CID in a communication system according to an embodiment of the present invention; 
           [0021]      FIG. 3  is a signal flow diagram illustrating allocation of a private transport CID in a communication system according to an embodiment of the present invention; 
           [0022]      FIG. 4  is a signal flow diagram illustrating a handover process in the case of using a transport CID in a communication system according to an embodiment of the present invention; and 
           [0023]      FIG. 5  is a signal flow diagram illustrating a handover process in the case of using a private transport CID in a communication system according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIGS. 1 through 5 , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged communication system. 
         [0025]    The present invention a private transport CID, which is a specific CID used within only one MS, will be described. 
         [0026]      FIG. 1  illustrates allocation of a private transport CID in a communication system. 
         [0027]    Referring to  FIG. 1 , the communication system includes a BS, a MS 1 , and a MS 2 , and a MS 3 . 
         [0028]    It is assumed that the MS 1  and the MS 3  and the MS 3  are MSs using a communication service from the BS.  FIG. 1  shows three service flows provided by the BS, and each of the three service flows is allocated a specific CID. The CID allocated to each MS by the BS is a Private CID (P-CID) proposed by the present invention. 
         [0029]    If the first Mobile Station MS uses the first service flow, the BS allocates “1” to an Service Flow Identifier (SFID) according to use of the first service flow (SFID=1). 
         [0030]    If the MS 2  uses the second service flow, the BS allocates “2” to an SFID according to use of the second service flow (SFID=2). Further, if the MS 3  uses the third service flow, the BS allocates “3” to an SFID according to use of the third service flow (SFID=3). 
         [0031]    The BS allocates “101” to the private transport CID (transport P-CID=101) for the SFID (SFID=1) of the MS 1 . Further, the BS allocates “101” to the private transport CID (transport P-CID=101) for the SFID (SFID=2) of the MS 2 , and the BS allocates “102” to the private transport CID (transport P-CID=102) for the SFID (SFID=3) of the MS 3 . 
         [0032]    As noted from the above description, the same private transport CID is allocated to MSs using different service flows, and different MSs communicating with the BS use the same private transport CID. However, the MS 1  and the MS 2  are actually connected through different service flows. 
         [0033]    That is to say, although the private transport CID has a unique value in view of each MS, multiple MSs may have the same private transport CID in view of one cell. However, even when the same private transport CID has been allocated to multiple MSs, the BS is aware that there are different SFIDs corresponding to the private transport CID. The MSs using the private transport CID can keep on using the existing private transport CID in using a service from a new BS even after the handover to another BS. Therefore, it is unnecessary for an MS using the private transport CID to perform a separate CID update. 
         [0034]    Meanwhile, in order to use a private transport CID, the BS may allocate a resource for data burst transmission/reception to each MS. That is, the BS indicates which data burst an MS may receive, by inserting a basic CID or an RCID (Reduced CID) into an HARQ MAP IE corresponding to data burst allocation information. Since each MS possesses a specific basic CID (RCID), the MS can receive a data burst corresponding to the MS itself. Therefore, the corresponding MS does not receive a data burst transmitted to another MS. Since all MAP IEs for uplink data burst transmission include a basic CID, the uplink transmission has no problem. The RCID refers to a Reduced CID, which has a size of eight (8) bits or twelve (12) bits while the basic CID generally has a size of sixteen (16) bits. 
         [0035]      FIG. 2  is a signal flow diagram illustrating allocation of a private transport CID in a communication system according to an embodiment of the present invention. 
         [0036]    Referring to  FIG. 2 , the communication system includes a BS  410 , a MS 1   420 , and a MS 2   430 . 
         [0037]    The BS  410  broadcasts a private transport CID information message having a specific value within each MS through, for example, a Downlink Channel Descriptor (DCD) message in order to use a private transport CID (step  411 ). 
         [0038]    The private transport CID information indicates a range of the CID value which the private transport CID may have. For example, the private transport CID value can be allocated by using a part of the transport CID value. 
         [0039]    Some of the transport CIDs (2m+1 to FE9F, wherein m refers to a value that can be optionally set by the BS) can be allocated to private transport CIDs. At this time, the BS may not use the CIDs, which have been allocated to the private transport CIDs, as the transport CIDs. As a result, it is possible to prevent collision between an MS using the transport CID and an MS using the private transport CID. 
         [0040]    The range of the private transport CID can be inserted in a form of Type-Length-Value (TLV) into a DCD message. Examplary, table 2 below shows a private transport CID TLV inserted in a DCD message. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Type 
                 Length 
                 Value 
                   
               
               
                 Name 
                 (1 byte) 
                 (1 byte) 
                 (4 byte) 
                 Scope 
               
               
                   
               
             
             
               
                 Private 
                 NNN 
                 2 
                 Bit#0-15: Start range of 
                 DCD 
               
               
                 Transport 
                   
                   
                 Private Transport CID 
               
               
                 CID range 
                   
                   
                 Bit#16-31: End range of Private 
               
               
                   
                   
                   
                 Transport CID 
               
               
                   
               
             
          
         
       
     
         [0041]    The TLV shown in Table 2 is included in a message (e.g. DCD message) periodically broadcasted by the BS, and an MS having received the broadcasted message can identify the private transport CID. 
         [0042]    The private transport CID range included in the DCD message may have, for example, a start CID value of 100 and a final CID value of 120. 
         [0043]    Upon receiving the DCD message, the MS 1   420  transmits a first message, which indicates if the MS 1   420  can use the private transport CID, to the BS  410  (step  413 ). The first message may be a registration (REG) message, a ranging message, or an MS basic capability message. 
         [0044]    Examplary, table 3 below shows a TLV field indicating if it is possible to use the private transport CID. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                 Type 
                 Length 
                 Value 
                   
               
               
                 Name 
                 (1 byte) 
                 (1 byte) 
                 (1 byte) 
                 Scope 
               
               
                   
               
             
             
               
                 Private 
                 NNN 
                 1 
                 Bit#0: 1 - Enable, 0 - Disable 
                 SBC or 
               
               
                 Transport 
                   
                   
                   
                 REG 
               
               
                 CID 
               
               
                 Enable 
               
               
                   
               
             
          
         
       
     
         [0045]    Upon receiving the first message including the TLV, the BS  410  can report to the MS 1   420  that the MS 1   420  can use the private transport CID. 
         [0046]    When it is possible to allocate a private transport CID to the MS 1   420 , the BS allocates the private transport CID to the MS 1   420  through a Dynamic Service Addition (DSA) message (step  415 ). 
         [0047]    The BS  410  transmits a private transport CID having a specific identifier within the MS 1   420  to the MS 1   420 . The following description is based on an assumption that the private transport CID is “100.” Upon receiving the DSA message, the MS 1   420  compares the allocated CID value with the private transport CID range received in step  411 , thereby determining if the allocated CID is a private transport CID or a transport CID. 
         [0048]    Thereafter, the BS  410  and the MS 1   420  can exchange data by using a private transport CID. 
         [0049]    Next, when the MS 2   430  has received the DCD message, the MS 2   430  determines if the MS 2   430  can use the private transport CID, by using the first message transmitted to the BS  410  (step  417 ). 
         [0050]    The MS 2   430  can transmit an SBC message or an REG message, which indicates if it is possible to support the private transport CID, to the BS  410 . The private transport CID enable TLV for transmitting a message indicating if it is possible to use the private transport CID from the MS 2   430  to the BS  410  has been described above with reference to Table 3, so a detailed description thereof will be omitted here. 
         [0051]    From the private transport CID availability confirmation message, the BS  410  can confirm that the BS  410  can allocate a private transport CID to the MS 2   430 . 
         [0052]    When it is possible to allocate a private transport CID to the MS 2   430 , the BS  410  allocates the private transport CID to the MS 2   430  through a DSA message (step  419 ). 
         [0053]    The private transport CID allocated by the BS  410  overlaps with the private transport CID possessed by each MS, and the same private transport CID can be allocated to both the MS 1   420  and the MS 2   430 . Further, through the DSA message, the MS 2   430  can compare the allocated CID with the private transport CID received in step  411 , so as to determine if the allocated CID is a private transport CID or a transport CID. 
         [0054]      FIG. 3  is a signal flow diagram illustrating allocation of a private transport CID in a communication system according to an embodiment of the present invention. 
         [0055]    Referring to  FIG. 3 , the communication system includes a BS  510 , a MS 1   520 , and a MS 2   530 . 
         [0056]    The BS  510  broadcasts a private transport CID information message having a specific value within each MS through, for example, a DCD message in order to use a private transport CID (step  511 ). 
         [0057]    Upon receiving the DCD message, the MS 1   520  transmits a first message, which indicates if the MS 1   520  can use the private transport CID, to the BS  510  (step  513 ). 
         [0058]    Steps  511  to  513  are the same as steps  411  to  413  of  FIG. 4 , so a detailed description thereof is omitted here. 
         [0059]    In order to transmit a data burst to each MS, the BS uses an HARQ DL MAP IE including a basic CID or an RCID. In the case of uplink, the BS uses a UL MAP IE or a UL HARQ MAP IE in order to receive a data burst from the MS. 
         [0060]    Thereafter, the BS  510  and the MS 1   520  can exchange data by using a private transport CID. 
         [0061]    Next, when the MS 2   530  has received the DCD message, the MS 2   530  transmits the first message to the BS  510  in order to report that the MS 2   530  is unable to use the private transport CID (step  517 ). 
         [0062]    The MS 2   530  can transmit an SBC message or an REG message, which indicates if it is possible to support the private transport CID, to the BS  510 . 
         [0063]    From the private transport CID availability confirmation message, the BS  510  can confirm that the BS  510  cannot allocate a private transport CID to the MS 2   530 . 
         [0064]    When it is possible to allocate a transport CID to the MS 2   530 , the BS  510  allocates the transport CID to the MS 2   530  through a DSA message (step  519 ). 
         [0065]    The BS transmits the transport CID to the MS 2   530 . Further, upon receiving the DSA message, the MS 2   530  can compare the allocated CID with the private transport CID received in step  511 , so as to determine if the allocated CID is a private transport CID or a transport CID. 
         [0066]    As described above, the BS allocates a transport CID to an MS that does not support the private transport CID. 
         [0067]      FIG. 4  is a signal flow diagram illustrating a handover process in the case of using a transport CID in a communication system according to an embodiment of the present invention. 
         [0068]    Referring to  FIG. 4 , the communication system includes a first Base Station (BS 1 )  610 , a Mobile Station (MS)  620 , and a second Base Station (BS 2 )  630 . 
         [0069]    The MS  620  is connected with the BS 1   610  by using a transport CID, which has a value of, for example, 99. It is assumed that an SFID corresponding to the transport CID is 1034. 
         [0070]    When the MS  620  detects a necessity of handover to a new BS (i.e. target BS) due to movement of the MS  620 , etc., the MS  620  transmits a handover request (HO-REQ) message to the BS 1   610  (step  611 ). 
         [0071]    In response to the handover request from the MS  620 , the BS 1   610  transmits a handover response (HO-RSP) message reporting that the MS  620  is allowed to handover (step  613 ). 
         [0072]    Upon receiving the handover response message, the MS  620  transmits a handover indication (HO-IND) message indicating change of the service connection point from the BS 1   610  to the BS 2   630 , that is, indicating that it will handover from the BS 1   610  to the BS 2   630  (step  615 ). 
         [0073]    Then, the MS  620  transmits a ranging request (RNG-REQ) message to the BS 2   630  (step  617 ). 
         [0074]    In response to the ranging request message, the BS 2   630  transmits a ranging response (RNG-RSP) message to the MS  620  (step  619 ). As the MS  620  newly enters the BS 2   630 , the BS 2   630  can insert a private transport CID in the ranging response message transmitted to the MS  620 . If the MS  620  uses the existing SFID, which has been used between the MS  620  and the BS 1   610  and has a value of 1034, the BS 2   630  allocates a private transport CID, which has a value of, for example, 100, for communication with the MS  620 . It is selected from a range of the CID value which the private transport CID may have. For example, the private transport CID value can be allocated by using a part of the transport CID value. 
         [0075]    According to the handover, the MS  620  performs a process of being allocated the private transport CID. Hereinafter, a handover process in the case of using the private transport CID will be described with reference to  FIG. 5 . 
         [0076]      FIG. 5  is a signal flow diagram illustrating a handover process in the case of using a private transport CID in a communication system according to an embodiment of the present invention. 
         [0077]    Referring to  FIG. 5 , the communication system includes a BS 1   710 , MS  720 , and a BS 2   730 . 
         [0078]    The MS  720  is connected with the BS 1   710  by using a private transport CID, which has a value of, for example, 100. 
         [0079]    When the MS  720  detects a necessity of handover to a new BS, i.e. BS 2   730 , due to movement of the MS  720 , etc., the MS  720  transmits a handover request (HO-REQ) message to the BS 1   710  (step  711 ). 
         [0080]    In response to the handover request from the MS  720 , the BS 1   710  transmits a handover response (HO-RSP) message reporting that the MS  720  is allowed to handover (step  713 ). 
         [0081]    Upon receiving the handover response message, the MS  720  transmits a handover indication (HO-IND) message indicating that it will handover from the BS 1   710  to the BS 2   730  (step  715 ). 
         [0082]    Then, the MS  720  transmits a ranging request (RNG-REQ) message for communication with the BS 2   730  to the BS 2   730  (step  717 ). 
         [0083]    In response to the ranging request message, the BS 2   730  transmits a ranging response (RNG-RSP) message to the MS  720  (step  719 ). If the BS 2   730  supports use of private transport CIDs by the MS  720  and supports connection using all private transport CIDs allocated to the MS  720 , the BS 2   730  transmits a private transport CID continue TLV recommending continuous use of the existing private transport CIDs having been used by the MS  720 . The MS  720  can receive the private transport CID continue TLV through the ranging response message, etc. The MS  720  receives a message indicating if it can use the private transport CID from the target BS 2   730 . 
         [0084]    When the MS  720  has received the private transport CID continue TLV, the MS  720  uses the existing private transport CIDs having been used between the previous BS 1   710  and the MS  720  as it is. That is, the MS  720  communicates with the BS 2   730  by using the existing private transport CID having a value of 100. 
         [0085]    If the BS 2   730  cannot support a private transport CID or cannot support private transport CIDs for all connections of the MS  720 , the BS 2   730  performs CID update by using the transport CID as shown in  FIG. 4 . 
         [0086]    Then, the MS  720  performs a process of being allocated a new transport CID according to handover. If the MS  720  can identify the private transport CID through the BS 2   730  in advance, the MS  720  can transmit/receive data even without receiving the private transport CID continue TLV. 
         [0087]    In other words, by using the private transport CID proposed by the present invention, an MS can perform communication by using an already allocated private transport CID even without performing a separate CID update process. 
         [0088]    In a communication system according to the present invention as described above, a BS allocates a specific transport CID, which is unique within each MS, to each MS. Since the private transport CID can be shared by multiple MSs within the entire system, a transport CID update process is not indispensable. Therefore, it is possible to prevent wasting of resources due to the transport CID update process. Further, it is unnecessary to allocate a new transport CID due to movement of an MS even in the case of handover, which allows fast handover. Moreover, use of the private transport CID allows communication through additional allocation of a basic CID and a primary management CID. 
         [0089]    Although the present disclosure has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.