Abstract:
A method for operating a Base Station (BS) in a wireless communication system includes, when a bandwidth request message is received from a Mobile Station (MS), whether a resource allocated to the MS exists is determined. When the resource allocated to the MS does not exist, a resource is temporarily allocated to the MS. A message indicating a network initial entry is transmitted to the MS using the temporarily allocated resource.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY 
     The present application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed in the Korean Intellectual Property Office on Nov. 28, 2008 and allocated Serial No. 10-2008-0119929, the entire disclosure of which is hereby incorporated by reference. 
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a wireless communication system. More particularly, the present invention relates to a method for resuming a service when a state mismatching between a Base Station (BS) and a Mobile Station (MS) occurs in a wireless communication system. 
     BACKGROUND OF THE INVENTION 
     In a current communication system, a study for providing services having various Quality of Services (QoS) of high speed to users is in active progress. Recently, research and development of a broadband wireless communication system called a 4-th Generation (4G) communication system, such as a wireless Local Area Network (LAN) system and a wireless Metropolitan Area Network (MAN), or an Institute of Electrical and Electronics Engineers (IEEE) 802.16e communication system are in active progress. 
       FIG. 1  illustrates a view of a conventional broadband wireless communication system. 
     Referring to  FIG. 1 , Access Control Routers (ACRs)  120  and  122  of the broadband wireless communication system are connected with an Internet Protocol (IP) Network  130 , and Base Stations (BSs)  110  to  116 . The ACRs  120  and  122  transmit/receive data to/from Mobile Stations (MSs)  100  to  106  via a wireless interface at a wired network terminal. That is, the ACRs  120  and  122  control the MSs  100  to  106 , and the BSs  110  to  116 , and route an IP packet. Additionally, the ACRs  120  and  122  cooperate with the BSs  110  and  116 , manage mobility of the MSs  100  to  106 , generate/inform charging and statistical information, provide QoS, and manage/control authentication/security and wireless resources. Each of the BSs  110  to  116  is connected with the MSs  100  to  106  for receiving a subscriber service to form a wireless section. The BSs  110  to  116  perform a call process for setting, maintaining, and releasing call connection of a packet, and are responsible for a handover, a system control, and matching of an additional device. 
     When a message to be transmitted/received is lost, an error occurs during a handover, or an error occurs in an internal resource of the BS  110  while the BS  110  and the MS  100  transmit/receive data to/from each other, a resource allocated by the BS  110  to the MS  100  that is in an active state may be deleted due to resource state mismatching between the BS  110  and the MS  100 . A phenomenon that a resource allocated to the MS  100  is improperly deleted may occur in various circumstances besides the above-described case. 
     When the resource is deleted, the MS  100  cannot receive a data service. When the MS  100  has data or a message to be transmitted to an uplink, the MS  100  transmits a Bandwidth Request Header (BRHdr) requesting a BS to allocate a bandwidth in order to obtain an uplink allocation. At this point, the BS  110  that has received the BRHdr determines a Basic Connection IDentifier (BCID) included in the BRHdr, and ignores the bandwidth allocation request because a currently allocated resource does not exist in the MS  100 . Here, the BCID is an identifier of the MS used when the MS performs an initial ranging and transmits/receives a Media Access Control (MAC) management message. 
     When the above-described procedure continues, the MS  100  cannot receive a service any more, and repeatedly and constantly transmits the BRHdr to the BS  110 . This is because the MS  100  cannot recognize a state mismatching between the MS  100  and the BS  110 . To resolve this mismatching, an event, such as re-authentication and network re-entry, should occur. However, under the above-described circumstance, the state mismatching between the MS  100  and the BS  110  cannot be resolved because the MS  100  cannot detect a current state. 
     SUMMARY OF THE INVENTION 
     To address the above-discussed deficiencies of the prior art, it is a primary aspect of the present invention to provide a method for resolving mismatching between a BS and an MS in a wireless communication system. 
     Another aspect of the present invention is to provide a method for allowing a BS to command an MS to perform a network initial entry in a wireless communication system. 
     In accordance with an aspect of the present invention, a method for operating a Base Station (BS) in a wireless communication system is provided. The method includes: when a bandwidth request message is received from a Mobile Station (MS), determining whether a resource allocated to the MS exists; when the resource allocated to the MS does not exist, temporarily allocating a resource to the MS; and transmitting a message indicating a network initial entry to the MS using the temporarily allocated resource. 
     Other aspects, advantages and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
     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; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. 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, as well as future uses of such defined words and phrases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  illustrates a view of a conventional broadband wireless communication system; 
         FIG. 2  illustrates a procedure for transmitting/receiving a message during a state mismatch between a BS and an MS in a broadband wireless communication system according to an exemplary embodiment of the present invention; and 
         FIG. 3  illustrates an operating procedure of a BS according to an exemplary embodiment of the present invention. 
     
    
    
     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 2 through 3 , 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 wireless communications system. 
     The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     Exemplary embodiments of the present invention provide a method for processing a state mismatching between a BS and an MS in a broadband wireless communication system. The present invention is described using an Orthogonal Frequency Division Multiplexing (OFDM)/Orthogonal Frequency Division Multiple Access (OFDMA) wireless communication system as an example, and is applicable to a wireless communication system of a different scheme. 
     A message transmission/reception procedure and an operation and a construction of an exemplary embodiment of the present invention are described in more detail with reference to the accompanying drawings. 
       FIG. 2  illustrates a procedure for transmitting/receiving a message during a state mismatch between a BS and an MS in a broadband wireless communication system according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , the BS  110  deletes a resource for the MS  100  that is in an active state due to a reason of the above-described message loss or internal error in step  202 . The deletion of the resource may be performed by a different reason other than the above-described reason. Therefore, a state mismatching between the MS  100  and the BS  110  occurs. The MS  100  that includes user data or a message to be transmitted to an uplink transmits a BRHdr to the BS  110  in order to request a bandwidth required for uplink transmission in step  204 . The BS  110  that has received the BRHdr recognizes that a resource allocated to the MS  100  has been deleted by determining the BCID included in the BRHdr, and searches a history of a past resource allocation using the BCID in step  206 . The BS  110  temporarily allocates a resource to the MS  100  in step  208 , and transmits a RESet CoMmanD (RES-CMD) message to the MS  100  using the temporarily allocated resource in step  210 . The MS  100  that has received the RES-CMD message initializes an MAC resource by performing an initial operation by itself in step  212 , and performs a network initial entry procedure with the BS  110  in step  214 . 
       FIG. 3  illustrates an operating procedure of a BS according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 3 , the BS deletes a resource for the MS that is in an active state due to a reason of the above-described message loss or internal error in step  302 . At this point, the MS having user data or a message to be transmitted to an uplink transmits a BRHdr to the BS in order to request a bandwidth required for uplink transmission. The BS receives the BRHdr in step  304 . The BS that has received the BRHdr determines whether the MS is an MS to which a resource has been allocated by determining a BCID included in the BRHdr in step  306 . When the MS is an MS to which a resource has been currently allocated as a result of the determination of the BCID, the BS normally performs data transmission/reception with the MS in step  316 . Alternatively, when the MS is not an MS to which a resource has been currently allocated but an MS for which a resource has been deleted as a result of the determination of the BCID, the BS searches a history of past resource allocation for the MS in step  308 . Through the above-described procedure, the BS recovers the resource that was allocated to the MS and temporarily allocates the resource in step  310 . Subsequently, the BS transmits an RES-CMD message to the MS via the temporarily allocated resource in step  312 . The BS performs a network initial entry procedure with the MS in step  314 , and normally transmits/receives data with the MS in step  316 . 
     In the exemplary embodiment of the present invention described with reference to  FIGS. 2 and 3 , the BS transmits an RES-CMD message in order to allow the MS to initialize a resource. The RES-CMD message is a message for commanding an MS to perform initialization, and may be configured as in Table 1. 
     
       
         
               
               
               
             
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Syntax 
                 Size 
               
               
                   
                   
               
             
             
               
                   
                 RES-CMD_Message_Format( ) { 
                 — 
               
             
          
           
               
                   
                 Management Message Type = 25 
                 8 
               
               
                   
                 TLV encoded information 
                 variable 
               
             
          
           
               
                   
                 } 
                 — 
               
               
                   
                   
               
             
          
         
       
     
     According to an exemplary embodiment of the present invention, the BS may transmit a different message other than the RES-CMD message. For example, a RaNGing ReSPonse (RNG-RSP) message including an abort Type Length Value (TLV), or a DeREGistration CoMmanD (DREG-CMD) message may be used. 
     As described above, when a BRHdr is received from an MS for which a resource has been deleted, a BS does not ignore the BRHdr but searches a history of past resource allocation to allocate a temporary resource, and transmits an RES-CMD message to the MS. Therefore, the BS allows the MS to recognize state mismatching between the BS and the MS and performs a network initial entry procedure. That is, a problem that the MS cannot recognize this state mismatching and repeatedly transmits a BRHdr is resolved, and a normal service resume becomes possible swiftly. 
     Although the invention has been shown and described with reference to certain exemplary embodiments 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 invention as defined by the appended claims and their equivalents. Therefore, the scope of the present invention should not be limited to the above-described embodiments but should be determined by not only the appended claims but also the equivalents thereof.