Abstract:
The present invention relates to a resource allocation and data receiving method. A resource allocation message for allocating a resource for an uplink dedicated channel is transmitted to a relay station, a receipt check message on the resource allocation message is received from the relay station, and successful resource allocation is checked.

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a resource allocation and data receiving method, and particularly, it relates to a data receiving method applying a reliable resource allocation method and a HARQ in a relay system. 
     (b) Description of the Related Art 
     The IEEE 802.16j task group (TG) has standardized the mobile multi-hop relay system.  FIG. 1  shows a schematic diagram of a mobile multi-hop relay system according to the related art. As shown in  FIG. 1 , the mobile multi-hop relay system includes a relay station (RS), a multi-hop relay base station (MR-BS), and a mobile station (MS). The RS relays data between the MR-BS and the MS, and the MS can directly communicate with the MR-BS, and can communicate with at least one RS. 
     In the mobile multi-hop relay system, the RS receives a relay station uplink dedicated channel (RS_UL_DCH) from the MR-BS so as to transmit data to the MR-BS, and the RS_UL_DCH represents a channel that is allocated by fixing a resource in the uplink. 
     The RS_UL_DCH is managed by an RS_UL_DCH assignment information element (RS_UL_DCH assignment IE).  FIG. 2  shows a resource allocation method according to the related art. As shown in  FIG. 2 , the RS_UL_DCH assignment IE is unidirectionally transmitted from the base station to the RS, and the resources used by the BS and the RS when the RS_UL_DCH assignment IE generates a loss because of a change of the radio channel are mismatched. That is, after transmitting the RS_UL_DCH assignment IE, the MR-BS considers that the RS will transmit data through a dedicated resources B that is allocated through the RS_UL_DCH assignment IE, but the RS transmits the data through a previously allocated dedicated resource A. Therefore, when the RS_UL_DCH assignment IE is lost, the data that are transmitted through the RS_UL_DCH are lost. 
     According to the related art, when the MR-BS transmits data through the RS_UL_DCH, it has no skill of controlling transmission errors. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to provide a reliable resource allocation method and data receiving method for controlling a transmission error. 
     An exemplary embodiment of the present invention provides a method for a base station to allocate a resource, including: transmitting a resource allocation message for allocating a resource for an uplink dedicated channel to a relay station; and checking that the resource is successfully allocated by receiving a receipt check message on the resource allocation message from the relay station. 
     Another embodiment of the present invention provides a method for a base station to receive data, including: checking whether data that are received from a relay station through an uplink dedicated channel have an error; and transmitting a data retransmission request message to the relay station when the received data are found to have an error. 
     Yet another embodiment of the present invention provides a method for a relay station to transmit data, including: receiving a retransmission request message on the data that are transmitted through an uplink dedicated channel from a base station; and retransmitting the data that are requested to be retransmitted by the retransmission request message. 
     According to the present invention, a resource of the RS_UL_DCH can be allocated with reliability, and a transmission error of the data that are received through the RS_UL_DCH can be controlled. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic diagram of a mobile multi-hop relay system according to the related art. 
         FIG. 2  shows a conventional resource allocation method according to the related art. 
         FIG. 3  shows a flowchart of a resource allocation method according to an exemplary embodiment of the present invention. 
         FIG. 4  shows a message flow in the case of a single hop in a resource allocation method according to an exemplary embodiment of the present invention. 
         FIG. 5  shows a message flow in the case of a multi-hop in a resource allocation method according to an exemplary embodiment of the present invention. 
         FIG. 6  shows a message flow when an RS_UL_DCH assignment IE is lost in a resource allocation method according to an exemplary embodiment of the present invention. 
         FIG. 7  shows a message flow when an RS UL_DCH header with DCH assignment acknowledgement is lost in a resource allocation method according to an exemplary embodiment of the present invention. 
         FIG. 8  shows a message format of an RS UL_DCH header with DCH assignment acknowledgement. 
         FIG. 9  shows a flowchart of a data receiving method according to an exemplary embodiment of the present invention. 
         FIG. 10  shows a field of an RS_UL_DCH HARQ Retx IE according to an exemplary embodiment of the present invention. 
         FIG. 11  shows a data receiving method in the case of using an in-band method according to an exemplary embodiment of the present invention. 
         FIG. 12  shows a data receiving method in the case of using an out-band method according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. For clarification of drawings in the present invention, parts that are not related to the description will be omitted, and the same parts will have the same reference numerals throughout the specification. 
     Throughout the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. Also, the terms of a unit, a device, and a module in the present specification represent a unit for processing a predetermined function or operation, which can be realized by hardware, software, or combination of hardware and software. 
     A resource allocation method according to an exemplary embodiment of the present invention will now be described with reference to  FIGS. 3 to 8 .  FIG. 3  shows a flowchart of a resource allocation method according to an exemplary embodiment of the present invention,  FIG. 4  shows a message flow in the case of a single hop in a resource allocation method according to an exemplary embodiment of the present invention,  FIG. 5  shows a message flow in the case of a multi-hop in a resource allocation method according to an exemplary embodiment of the present invention,  FIG. 6  shows a message flow when an RS_UL_DCH assignment IE is lost in a resource allocation method according to an exemplary embodiment of the present invention, and  FIG. 7  shows a message flow when an RS UL_DCH header with DCH assignment acknowledgement having a dedicated channel allocation receipt report is lost in a resource allocation method according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 3 , the MR-BS transmits an RS_UL_DCH assignment IE that is a fixed resource allocation message to the RS (S 310 ). The RS_UL_DCH assignment IE represents a message for allocating a resource for the RS_UL_DCH. When normally receiving the RS_UL_DCH assignment IE from the MR-BS, the RS includes a DCH assignment acknowledgement message for indicating a normal receipt of the RS_UL_DCH assignment IE into a header of the RS UL_DCH, and transmits the same to the MR-BS. That is, the RS transmits an RS UL_DCH header with DCH assignment acknowledgement to the MR-BS. When receiving the RS UL_DCH header with DCH assignment acknowledgement from the RS (S 320 ), the MR-BS checks that a resource is successfully allocated to the RS_UL_DCH (S 340 ). 
     Here, the RS UL_DCH header with DCH assignment acknowledgement is transmitted to the first position of the first frame at which the allocated resource is activated.  FIG. 8  shows a message format of an RS UL_DCH header with DCH assignment acknowledgement. Referring to  FIG. 8 , when “TYPE” is given as “0001,” it means that the message is a DCH assignment acknowledgement. In  FIG. 8 , the RS UL_DCH header with a DCH assignment acknowledgement message includes a frame number, and the frame number indicates a frame for receiving the RS_UL_DCH assignment IE. 
     Regarding the message flow in the case of a single hop with reference to  FIG. 4 , the RS_UL_DCH assignment IE is normally transmitted from the MR-BS to the RS, and the RS UL_DCH header with DCH assignment acknowledgement is normally transmitted from the RS to the MR-BS to know that the resource allocated for the RS_UL_DCH is activated between the MR-BS and the RS. 
     Regarding the message flow in the case of a multi-hop with reference to  FIG. 5 , when the MS-BS transmits an RS_UL_DCH assignment IE  1  to the RS  1 , the RS  1  transmits an RS_UL_DCH assignment IE  2  to the RS  2 . In this instance, the RS_UL_DCH assignment IE  2  may be generated by the MS-BS or the RS  1 . The RS  1  transmits the RS UL_DCH header with DCH assignment acknowledgement  1  to the MR-BS, and the RS  2  transmits the RS UL_DCH header with DCH assignment acknowledgement  2  to the RS  1 . 
     When the RS_UL_DCH assignment IE is lost as shown in  FIG. 6  or the RS UL_DCH header with DCH assignment acknowledgement is lost as shown in  FIG. 7 , the MR-BS cannot receive the RS UL_DCH header with DCH assignment acknowledgement. The MR-BS then retransmits the RS_UL_DCH assignment IE (S 330 ). 
     When the resource of the RS_UL_DCH is allocated by the resource allocation method according to the exemplary embodiment of the present invention, the MS-BS receives data from the RS through the allocated resource of the RS_UL_DCH. 
     A data receiving method according to an exemplary embodiment of the present invention will now be described with reference to  FIG. 9  to  FIG. 12 . 
       FIG. 9  shows a flowchart of a data receiving method according to an exemplary embodiment of the present invention. As shown in  FIG. 9 , the MR-BS negotiates with the RS regarding whether to a hybrid automatic retransmit request (HARQ) function (S 810 ). Table 1 shows a field format used for negotiation regarding the usage of the HARQ function. Referring to Table 1, when using the HARQ function, the MR-BS notifies the RS of the maximum number of frames that are stored so as to retransmit the data transmitted by the RS. The RS determines that the data that are transmitted after the maximum frame number are successfully transmitted. 
     
       
         
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Type 
                 Length 
                 Value 
                 Scope 
               
               
                   
               
             
             
               
                 TBA 
                 1 
                 Bit #0: HARQ support for the 
                 SBC_REQSBC_RSP 
               
               
                   
                   
                 RS UL_DCH Bit #1-#2: 
               
               
                   
                   
                 Reserved Bit #3-#7: 
               
               
                   
                   
                 The maximum frame number of 
               
               
                   
                   
                 retransmission 
               
               
                   
               
             
          
         
       
     
     The MR-BS checks whether the data that are received from the RS through the RS_UL_DCH have an error (S 820 ), and when an error is detected, the MR-BS transmits an RS_UL_DCH HARQ retransmit information element (RS_UL_DCH HARQ Retx IE) that is a data retransmission request message to the RS (S 830 ).  FIG. 10  shows a field of an RS_UL_DCH HARQ Retx IE according to an exemplary embodiment of the present invention. 
     In  FIG. 10 , the frame number represents a frame number of data to be retransmitted, and the RS UL_DCH Identifier for HARQ indicates an identifier of a DCH when there are a plurality of dedicated channels (DCH) between the MR-BS and the RS. Therefore, the data to be retransmitted by the frame number and the RS UL_DCH Identifier for HARQ are designated. 
     The in-band or out-band Retx represents a data retransmission method. The retransmission method includes an in-band method and an out-band method. When the in-band or out-band Retx is 0, it indicates the in-band method, and when the in-band or out-band Retx is 1, it indicates the out-band method. 
     The in-band method retransmits data through the allocated resource of the RS_UL_DCH.  FIG. 11  shows a data receiving method in the case of using an in-band method according to an exemplary embodiment of the present invention. Referring to  FIG. 11 , a frame includes a downlink (DL) subframe and an uplink (UL) subframe, the downlink subframe and the uplink subframe respectively include an access region and a relay region, and a resource is allocated to the RS UL_DCH per 2 frames. The access region is a region in which the MR-BS communicates with the MS, and the relay region is a region in which the MR-BS communicates with the RS. 
     As shown in  FIG. 11 , when the resource of the RS_UL_DCH of the N-th frame generates a receiving error, the MR-BS transmits the RS_UL_DCH HARQ Retx IE to the RS to request data retransmission. In this instance, the RS_UL_DCH HARQ Retx IE can be transmitted in the access region and the relay region. 
     The out-band method additionally allocates a resource to retransmit data through the additionally allocated resource.  FIG. 12  shows a data receiving method in the case of using an out-band method according to an exemplary embodiment of the present invention. As shown in  FIG. 12 , when the resource of the RS_UL_DCH of the N-th frame generates a receiving error, the RS_UL_DCH HARQ Retx IE is transmitted to the RS by including information on the additionally allocated resource in the RS_UL_DCH HARQ Retx IE to request data retransmission. 
     As shown in  FIG. 10 , in the case of using the out-band method, the RS_UL_DCH HARQ Retx IE includes a subchannel offset field and a duration field to designate an additionally allocated resource. Changed coding and modulation information is transmitted through a UIUC field and a repetition coding indication field. 
     When receiving the RS_UL_DCH HARQ Retx IE from the MR-BS, the RS retransmits data to the MR-BS, and the MR-BS receives the data again (S 840 ). In this instance, in the case of using the in-band method, the RS retransmits the data through the fastest resource from among the allocated resources of the RS_UL_DCH channel, and in the case of using the out-band method, the RS retransmits the data through the additionally allocated resource. 
     The above-described embodiments can be realized through a program for realizing functions corresponding to the configuration of the embodiments or a recording medium for recording the program in addition to through the above-described device and/or method, which is easily realized by a person skilled in the art. 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.