Patent Publication Number: US-2009232072-A1

Title: Resource allocation apparatus and method in broadband wireless communication system

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 Mar. 14, 2008 and assigned Serial No. 10-2008-0023758, the entire disclosure of which is hereby incorporated by reference. 
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a resource allocation apparatus and method in a broadband wireless communication system. More particularly, the present invention relates to an apparatus and method for reducing an overhead of resource allocation information. 
     BACKGROUND OF THE INVENTION 
     Today, many wireless communication techniques are being proposed to achieve a high-speed mobile communication. Among them, an Orthogonal Frequency Division Multiplexing (OFDM) scheme is accepted as one of the preferred techniques for a next generation wireless communication. The OFDM scheme is expected to be widely used in the a future wireless communication technique, and currently is used as a standard in the Institute of Electrical and Electronics Engineers (IEEE) 802.16-based Wireless Metropolitan Area Network (WMAN) known as the 3.5 Generation (3.5G) technology. 
     In a Code Division Multiple Access (CDMA)-based communication system, a channel for data transmission is identified with a code, and thus a small amount of information is required for resource allocation. However, in an OFDM-based communication system, the channel for data transmission is identified in time and frequency domains, and thus an amount of information for resource allocation is significantly large. 
       FIG. 1  illustrates a frame structure of a conventional IEEE 802.16e system. 
     Referring to  FIG. 1 , a frame consists of one Downlink (DL) frame and one Uplink (UL) frame. The DL frame is a duration in which a base station (BS) transmits data to Mobile Stations (MSs). The UL frame is a duration wherein several MSs transmit data to the BS over a determined resource region. 
     The DL frame consists of a Frame Control Header (FCH), a DL-MAP, a UL-MAP, and DL data bursts. The UL frame consists of a control region (i.e., a Channel Quality Indicator CHannel (CQICH) region, an Acknowledgement Channel (ACKCH) region, a CDMA ranging region, etc.) and a UL data burst region. The FCH includes information on a basic configuration of the frame. The DL-MAP includes resource allocation information on DL data bursts. The UL-MAP includes resource allocation information on the UL frame. 
     As such, in case of the conventional IEEE 802.16e system, resource allocation information (i.e., DL-MAP and UL-MAP) to be transmitted to all users is coded in one channel-coding unit (i.e., one burst unit) and is then transmitted at a starting portion of the frame. An MS receives a MAP which is broadcast from the BS. If a Connection Identifier (CID) of the MS exists in a DL/UL-MAP Information Element (IE), data is received or transmitted according to information of a corresponding MAP IE. If the BS and the MS continuously communicate with each other, the BS has to transmit the resource allocation information to the MS in every frame. Such a process is referred to as joint coding. 
     Meanwhile, in IEEE 802.20 Ultra Mobile Broadband (UMB) and 3 rd  Generation Partnership Project (3GPP) Long Term Evolution (LTE), illustrated in  FIG. 2 , resource allocation information for each user is configured in a separate encoding block and then is transmitted in every frame. In this case, the resource allocation information for each user can be identified with a code. Such a process is referred to as separate coding. 
     In particular, since the resource allocation information is transmitted to each user in the separate coding, it is possible to transmit resource allocation information optimized to a channel condition of a corresponding MS. However, since the resource allocation information has to be transmitted to each of all users, an overhead of the MAP is great. Therefore, in case of using the separate coding, there is a need for a method capable of reducing a size of resource allocation information transmitted to each user. In particular, there is a need for a method capable of reducing an amount of information for resource indication included in the resource allocation information. 
     SUMMARY OF THE INVENTION 
     To address the above-discussed deficiencies of the prior art, it is a primary aspect of the present invention to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide an apparatus and method for effective resource indication in a broadband wireless communication system. 
     Another aspect of the present invention is to provide an apparatus and method for reducing an information amount for resource indication in a broadband wireless communication system. 
     Another aspect of the present invention is to provide an apparatus and method for reducing an information amount of resource allocation information in a broadband wireless communication system. 
     Another aspect of the present invention is to provide an apparatus and method for communication of resource allocation information in a broadband wireless communication system. 
     In accordance with an aspect of the present invention, a communication method of a BS in a broadband wireless communication system is provided. The method includes allocating a resource region to a user by performing resource scheduling, determining a node ID corresponding to the allocated resource region according to a hybrid resource structure based on a triangle structure in which at least one branch is configured as tree branch, configuring resource allocation information including the determined node ID, and transmitting the configured resource allocation information to the user. 
     In accordance with another aspect of the present invention, a communication method of a MS in a broadband wireless communication system is provided. The method includes receiving resource allocation information over a MAP region, extracting a node ID by analyzing the resource allocation information, determining a resource region corresponding to the node ID according to a hybrid resource structure based on a triangle structure in which at least one branch is configured as tree branch, and performing communication over the determined resource region. 
     In accordance with another aspect of the present invention, a BS apparatus in a broadband wireless communication system is provided. The apparatus includes a controller for allocating a resource region to a user by performing resource scheduling and for determining a node ID corresponding to the allocated resource region according to a hybrid resource structure based on a triangle structure in which at least one branch is configured as tree branch, a message configuration unit for configuring resource allocation information including the determined node ID, and a transmitter for transmitting the configured resource allocation information to the user. 
     In accordance with another aspect of the present invention, an MS apparatus in a broadband wireless communication system is provided. The apparatus includes a receiver for receiving resource allocation information over a MAP region, a message analyzer for extracting a node ID by analyzing the resource allocation information, and a controller for determining a resource region corresponding to the node ID according to a hybrid resource structure based on a triangle structure in which at least one branch is configured as tree branch and for performing communication over the determined resource region. 
     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 frame structure of a conventional IEEE 802.16e system; 
         FIG. 2  illustrates a frame structure of a conventional IEEE 802.20 UMB (Ultra Mobile Broadband) system; 
         FIGS. 3A and 3B  illustrate a frame structure in a broadband wireless communication system according to an exemplary embodiment of the present invention; 
         FIG. 4  illustrates a tree structure of resource indication for 8 Resource Blocks (RBs) according to an exemplary embodiment of the present invention; 
         FIG. 5  illustrates a resource structure for resource indication according to an exemplary embodiment of the present invention; 
         FIG. 6  is a flowchart illustrates an operation process of a base station in a broadband wireless communication system according to an exemplary embodiment of the present invention; 
         FIG. 7  is a flowchart illustrates an operation process of a mobile station in a broadband wireless communication system according to an exemplary embodiment of the present invention; 
         FIG. 8  is a block diagram illustrating a structure of a base station according to an exemplary embodiment of the present invention; and 
         FIG. 9  is a block diagram illustrating a structure of a mobile station according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 3A through 9 , 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 network. 
     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. 
     It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
     Hereinafter, a method of reducing an information amount for resource indication in a broadband wireless communication system will be described. 
     The present invention may apply to a communication system in which a BS configures resource allocation information in a MAP format and transmits the resource allocation information to a plurality of MSs. An IEEE 802.16m-based broadband wireless communication system will be described hereinafter as an example. 
       FIGS. 3A and 3B  illustrate an exemplary configuration of resource allocation information in a broadband wireless communication system according to an exemplary embodiment of the present invention. In particular, it is assumed in  FIGS. 3A and 3B  that the resource allocation information is configured in a MAP format, and the resource allocation information is transmitted by performing separate coding for each user. 
       FIG. 3A  illustrates a case where the resource allocation information is transmitted using Frequency Division Multiplexing (FDM). That is, a specific band is used for a MAP in a frequency axis, and remaining bands are used for user data. 
       FIG. 3B  illustrates a case where the resource allocation information is transmitted using Time Division Multiplexing (TDM). That is, a certain number of OFDM symbol regions are used for a MAP in a time axis, and the remaining regions are used for user data. 
     An IEEE 802.16m mini-frame (or subframe) is illustrated in  FIG. 3A . For example, in IEEE 802.16m, a certain number (e.g., eighteen (18)) of subcarriers are concatenated into one block per one mini-frame (e.g., six (6) OFDM symbols) at a bandwidth of ten (10) MHz to configure forty-eight (48) Resource Blocks (RBs). A resource allocation method for such a mini-frame (or subframe) will be described below as an example. 
       FIG. 4  illustrates a tree structure of resource indication for eight (8) RBs according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 4 , lowermost nodes belong to a 1 st  order, and respectively correspond to actually allocated RBs. Next four nodes belong to a 2 nd  order. Next two nodes belong to a 3 rd  order. Next one node belongs to a 4 th  order. In each order, each node is linked to two subordinate nodes through a branch. 
     In case of  FIG. 4 , supportable resource indication is configured into fifteen (15) sets as follows. 
     allocation size 1: RB #{0},{1},{2},{3},{4},{5},{6},{7} 
     allocation size 2: RB #{0,1},{2,3},{4,5},{6,7}, 
     allocation size 4: RB #{0,1,2,3}. {4,5,6,7} 
     allocation size 8: RB #{0,1,2,3,4,5,6,7} 
     For example, when RBs “11” to “14” are allocated, a resource indicator included in the resource allocation information is “010” that is a node ID. 
     The following requirements are necessary for effective resource indication in the broadband wireless communication system. 
     Requirement 1: Allocation has to be supported for RB sizes of one (1), two (2), and three (3) in order to indicate data having a small information amount such as a Voice over IP (VoIP) or a control channel. 
     Requirement 2: Waste of resources has to be minimized even when data having a large information amount is allocated. 
     Requirement 3: Allocation has to be supported for multiples of four (4) and six (6) in order to support an allocation method in which several RBs are concatenated to be allocated such as in band Adaptive Modulation and Coding (AMC). 
     Requirement 4: An information amount for resource indication has to be minimized while satisfying all of the requirements above in a mini-frame structure supporting forty-eight (48) RBs. 
     In order to satisfy Requirement  4  above, a tree structure is preferable for branches located in a lower portion of a resource structure. That is, since the number of nodes significantly increases in a lower portion, the information amount can be minimized by reducing the number of nodes by applying the tree structure at the lower portion. However, to satisfy Requirement 1 above, 1 st  and 2 nd  branches from a lowermost portion have to support a triangle structure. This is because, when the tree structure is applied at an n th  branch, a granularity of each node belonging to an (n+2) th  order is increased by an exponent of 2 in comparison with an (n+1) th  order. Therefore, a 3 rd  branch is used as a tree branch in the present invention. 
     To satisfy Requirement 3 above, a total number of tree branches has to be 2 or below. In addition, in order to use an nth node as a tree branch, a total number of nodes of an n th  order have to be odd. Therefore, a 5 th  branch is used as a 2 nd  tree branch in the present invention. 
     Now, a resource structure for resource indication suitable for a mini-frame consisting of forty-eight (48) RBs will be described as an example. 
       FIG. 5  illustrates a resource structure for resource indication according to an exemplary embodiment of the present invention. 
     A hybrid structure shown in  FIG. 5  is combination of a tree structure and a triangle structure. A 3 rd  branch and a 5 th  branch from a lowermost portion are configured in tree branches, and the remaining branches are configured in triangle branches. That is, the hybrid structure is based on a triangle structure and specific branches are configured as tree branches. In this case, a total number of nodes is two-hundred fifty-two (252), and an information amount for resource indication is eight (8) bits. 
     In case of  FIG. 5 , supportable resource indication is configured into 252 sets in total as follows. 
     allocation size 1 (48 sets): {0}, {1}, {2}, {3}, {4},˜,{47} 
     allocation size 2 (47 sets) {0,1}, {1,2}, {2,3}, {3,4},˜,{45,46}, {46,47} 
     allocation size 3 (46 sets): {0,1,2}, {1,2,3}, {2,3,4},˜{44,45,46}, {45,46,47} 
     allocation size 4 (23 sets): {0,1,2,3}, {2,3,4,5}, {4,5,6,7},˜,{44,45,46,47} 
     allocation size 6 (22 sets): {0,1,˜,4,5}, {2,3,∞,6,7}, {4,5,˜,8,9},˜,{42,43,∞,46,47} 
     allocation size 8 (11 sets): {0,1,∞,6,7}, {4,5,˜,10,11}, {8,9,˜14,15},˜,{40,41,˜,46,47} 
     allocation size 12 (10 sets): {0, 1,˜,10,11}, {4,5,˜,14,15},˜,{36,37,˜,46,47} 
     allocation size 16 (9 sets): {0,1,˜14,15}, {4,5,˜,18,19},˜,{32,33,˜,46,47} 
     allocation size 20 (8 sets): {0,1,˜14,19}, {4,5,˜,18,23},˜,{28,29,˜,46,47} 
     allocation size 24 (7 sets): {0,1,˜14,23}, {4,5,˜,22,27},˜,{24,25,˜,46,47} 
     allocation size 28 (6 sets): {0,1,˜14,27}, {4,5,˜,26,31},˜,{20,21,˜,46,47} 
     allocation size 32 (5 sets): {0,1,˜30,31}, {4,5,˜,30,35},˜,{16,17,˜,46,47} 
     allocation size 36 (4 sets): {0,1,˜34,35}, {4,5,˜,38,39},˜,{12,13,˜,46,47} 
     allocation size 40 (3 sets): {0,1,˜,38,39}, {4,5,˜,42,43}, {8,9,˜,46,47} 
     allocation size 44 (2 sets): {0,1,˜,42,43}, {4,5,˜,46,47} 
     allocation size 48 (1 set): {0,1,˜,46,47} 
     For example, as shown in  FIG. 5 , when RBs “ 2 ” to “ 5 ” are allocated, an information amount for resource indication can be compared as follows with respect to conventional methods and the proposed method of the present invention. 
     First, twelve (12) bits are required in a start-end method. That is, six (6) bits are required to specify a start RB, and six (6) bits are required to specify an end RB. A start RB “ 2 ” and an end RB “ 5 ” are indicated to specify the RBs “ 2 ” to “ 5 ” (i.e., start RB: 000010, end RB: 000101). 
     Seven (7) bits are required in a tree method. In case of the tree method, the RBs “ 2 ” to “ 5 ” cannot be specified due to a granularity problem. Therefore, a node seven (7) (i.e., node ID: 0000111) has to be indicated to specify RBs “ 0 ” to “ 7 ”. As such, more resources are allocated in the tree method than actually required resources, resulting in a problem of waste of resources. 
     Eleven (11) bits are required in a triangle method. In case of the triangle method, a node  943  (i.e., node ID: 01110101111) has to be indicated to specify the RBs “ 2 ” to “ 5 ”. 
     Forty-eight (48) bits are required in a bitmap method. That is, a first bit of a bitmap corresponds to an RB “ 0 ” and a last bit thereof correspond to an RB “ 47 ”. In this case, corresponding bits of the bitmap are set to ‘1’ (i.e., bitmap: 001111000000000000000000000000000000000000000000) to specify the RBs “ 2 ” to “ 5 ”. 
     Eight (8) bits are required in a hybrid method proposed in the present invention. That is, as shown in  FIG. 5 , a node  89  (i.e., node ID: 01011001) is indicated to specify the RBs “ 2 ” to “ 5 ”. As shown in  FIG. 5 , a node ID is numbered from an uppermost portion. The structure of  FIG. 5  is only one example, and thus may be easily extended by those skilled in the art. For example, when the number of RBs configured in a frame is changed, the structure of  FIG. 5  can be easily modified to fit the frame. 
     As such, an information amount for resource indication is smaller in the method of the present invention in comparison with the conventional method. In addition, the method of the present invention can solve the granularity problem. 
     A detailed operation of the present invention will be explained below on the basis of the above description. 
       FIG. 6  illustrates an operation of a BS in a broadband wireless communication system according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 6 , the BS performs resource scheduling in step  601 . That is, the BS selects users (or connections or service flows) to be served at a current frame, and determines a resource region for communication for each selected user. 
     After performing the resource scheduling, in step  603 , the BS determines a resource region (e.g., RBs) of an nth user (where n=1, 2, 3, . . . ) among users to be served. In step  605 , the BS determines a node ID corresponding to the determined resource region according to the hybrid structure (i.e., tree+triangle) of  FIG. 5 . In this case, the node ID may be calculated by a specific formula or may be obtained from a specific mapping table. 
     After determining the node ID for the resource region allocated to the n th  user, proceeding to step  607 , the BS configures resource allocation information (or MAP Information Element (IE)) of the nth user. In this case, the resource allocation information may include a variety of information, such as, a user identifier (e.g., Connection IDentifier (CID), Media Access Control (MAC) ID, Service Flow (SF) ID, etc.), a node ID corresponding to a resource region, coding information (e.g., Modulation and Coding Scheme (MCS) level) to be used in the resource region, etc. 
     After configuring the resource allocation information of the n th  user, proceeding to step  609 , the BS determines whether a next user exists. If the next user exists, the procedure returns to step  603  so that the BS configures resource allocation information of the next user. 
     If the next user does not exist, proceeding to step  611 , the BS generates a Cyclic Redundancy Check (CRC) code for each of the configured MAP IEs by using a different CRC generator polynomial, and appends the generated CRC code to corresponding MAP IE. The CRC generator polynomial differs from one user to another and may be reported to each user in an initial network entry process. Further, the BS encodes the MAP IE appended with the CRC code. In this case, the MAP IE can be encoded differently according to a user channel condition. Separate coding performed herein using the CRC code is for exemplary purposes only, and thus the separate coding can be performed in various manners in the present invention. For example, the separate coding may be performed on resource allocation information by using a different scrambling code for each user. 
     Thereafter, in step  613 , the BS transmits the encoded MAP IEs over a predetermined MAP region. 
       FIG. 7  illustrates an operation of an MS in a broadband wireless communication system according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 7 , the MS determines whether a MAP signal is received in step  701 . Upon receiving the MAP signal, in step  703 , the MS extracts pieces (or MAP IEs) of resource allocation information from the received MAP signal, and decodes each of the extracted MAP IEs. 
     In step  705 , the MS performs CRC on each of the MAP IEs. Specifically, the MS removes a CRC code from each of the MAP IEs, and generates the CRC code for each of the MAP IEs. Further, the MS compares the removed CRC code with the generated CRC code with respect to each of the MAP IEs, and determines resource allocation information of the MS when the two CRC codes are identical with each other. 
     In step  707 , the MS determines whether there is resource allocation information (or MAP IE) that has undergone the CRC. That is, the MS determines whether there is resource allocation information whose CRC code generated using its CRC generator polynomial is equal to the CRC code removed from received information. 
     If there is no resource allocation information that has undergone the CRC, the procedure returns to step  701 , so that the MS receives a next MAP. If there is the resource allocation information that has undergone the CRC, the MS extracts required information by analyzing corresponding resource allocation information in step  709 . Herein, the resource allocation information may include a variety of information, such as, a user identifier (e.g., CID, MAC ID, SF ID, etc.), a node ID corresponding to a resource region, coding information to be used in the resource region, etc. 
     In step  711 , the BS determines a resource region corresponding to a node ID extracted from the resource allocation information according to the hybrid structure of  FIG. 5 . In this case, the resource region (i.e., RBs) corresponding to the node ID may be calculated by a specific formula or may be obtained from a specific mapping table. As such, the MS determines the resource region allocated to the MS. 
     In step  713 , the MS performs communication (i.e., downlink communication or uplink communication) over the determined resource region. 
       FIG. 8  is a block diagram illustrating a structure of a BS according to an exemplary embodiment of the present invention. 
     The structure of  FIG. 8  focuses mainly on a transmitter. Referring to  FIG. 8 , the BS includes a controller  800 , a message generator  802 , a CRC adder  804 , a coder  806 , a modulator  808 , a resource mapper  810 , an OFDM modulator  812 , and a Radio Frequency (RF) transmitter  814 . 
     The controller  800  performs resource scheduling, and controls corresponding constitutional elements according to the scheduling result. In particular, the controller  800  allocates a resource region to each user by performing resource scheduling, and determines a node ID corresponding to each of the allocated resource regions according to the hybrid resource structure (see  FIG. 5 ) that is a combination of the tree structure and the triangle structure. 
     The message generator  802  generates various signaling messages under the control of the controller  800 . The message generator  802  configures resource allocation information (or MAP IE) to be transmitted to each user. In this case, the resource allocation information may include a variety of information, such as, a user identifier (e.g., CID, MAC ID, SF ID, etc.), a node ID corresponding to an allocated resource region, coding information (e.g., MCS level) to be used in the resource region, etc. 
     The CRC adder  804  appends a CRC for each user to each of MAP IEs received from the message generator  802 . That is, the CRC adder  804  calculates a CRC code for resource allocation information by using a CRC generator polynomial of a corresponding user, and appends the calculated CRC code to the resource allocation information. It is assumed that the CRC code for each user is agreed in advance between the BS and an MS. 
     The coder  806  codes a message received from the CRC adder  804  according to a determined MCS level. That is, the coder  806  performs separate encoding on each of the MAP IEs received from the CRC adder  804 . The coder  806  may use a Convolution Code (CC), a Turbo Code (TC), a Convolutional Turbo Code (CTC), a Low Density Parity Check (LDPC) code, etc. 
     The modulator  808  generates modulation symbols by modulating coded packets received from the coder  806  according to the determined MCS level. For example, the modulator  808  may use Quadrature Phase Shift Keying (QPSK), 16-Quadrature Amplitude Modulation (QAM), 64-QAM, etc. 
     The resource mapper  810  maps data received from the modulator  808  to a predetermined resource (or subcarrier). For example, the resource mapper  810  maps the MAP IEs to a MAP region. 
     The OFDM modulator  812  generates an OFDM symbol by performing OFDM demodulation on the resource-mapped data received from the resource mapper  810 . The OFDM demodulation includes an Inverse Fast Fourier Transform (IFFT) operation, a Cyclic Prefix (CP) insertion, etc. The RF transmitter  814  converts sample data received from the OFDM modulator  812  into an analog signal, converts the analog signal into an RF signal, and transmits the RF signal through an antenna. 
       FIG. 9  is a block diagram illustrating a structure of an MS according to an exemplary embodiment of the present invention. 
     The structure of  FIG. 9  focuses mainly on a receiver. Referring to  FIG. 9 , the MS includes an RF receiver  900 , an OFDM demodulator  902 , a resource de-mapper  904 , a demodulator  906 , a decoder  908 , a CRC operator  910 , a message analyzer  912 , and a controller  914 . 
     The RF receiver  900  converts an RF signal received through an antenna into a baseband signal, and converts the baseband signal into digital sample data. The OFDM demodulator  902  outputs frequency-domain data by performing OFDM demodulation on the sample data received from the RF receiver  900 . The OFDM demodulation includes a CP removal, a Fast Fourier Transform (FFT) operation, etc. 
     The resource de-mapper  904  extracts bursts from the frequency-domain data received from the OFDM demodulator  902 . The resource de-mapper  904  extracts MAP IEs received over a MAP region. 
     The demodulator  906  demodulates each piece of the MAP IEs received from the resource de-mapper  904 . The decoder  908  decodes each piece of the demodulated MAP IEs received from the demodulator  906 . 
     The CRC operator  910  performs a CRC operation on each piece of the MAP IEs received from the decoder  908  by using a predetermined CRC generator polynomial. That is, the CRC operator  910  removes a CRC code from each piece of the MAP IEs and generates a CRC code for each piece of the received MAP IEs. Further, the CRC operator  910  compares the removed CRC code with the generated CRC code for each piece of the MAP IEs and determines resource allocation information of the MS when the two CRC codes are identical with each other. 
     The message analyzer  912  analyzes resource allocation information (or MAP IE) that has undergone the CRC and which is received from the CRC operator  910  and provides the analysis result to the controller  914 . In this case, the resource allocation information may include a variety of information, such as, a user identifier, a node ID corresponding to an allocated resource region, coding information applied to the resource region, etc. 
     The controller  914  provides overall controls to the MS. If the resource allocation information is received, the controller  914  determines a resource region corresponding to a node ID included in the resource allocation information according to the hybrid resource structure (see  FIG. 5 ) that is a combination of the tree structure and the triangle structure. Further, the controller  914  controls a corresponding constitutional element to perform communication (i.e., downlink communication or uplink communication) over the determined resource region. 
     As described above, the present invention proposes an optimal resource structure capable of effectively reducing a size of resource allocation information. In other words, the present invention has an advantage in that the size of resource allocation information can be reduced by decreasing an information amount for resource indication. In addition, since resources are allocated in the present invention according to a hybrid structure that is a combination of a tree structure and a triangle structure, a degree of freedom in resource allocation can be increased and a granularity performance can be increased. A large amount of resources for data transmission can be ensured by reducing the resource allocation information, and thus an overall throughput of a system can be increased. 
     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.