Abstract:
A resource allocation method and apparatus in a communication system having backward compatibility are provided. In a transmission apparatus, a determiner determines a first frequency band for transmitting wireless resource allocation information to a terminal from among the frequency bands supporting the communication system, a MAP generator determines at least one second frequency band over which the terminal desires to receive a service and allocates wireless resources to the second frequency band, and a transmission unit transmits the wireless resource allocation information to the terminal over the first frequency band. In a reception apparatus, a reception unit receives wireless resource allocation information over a first frequency band determined by a base station and a MAP information decrypter determines at least one service frequency band included in the wireless resource allocation information. Accordingly, the method and apparatus dynamically allocate wireless resources to a terminal when multiple systems having backward compatibility coexist.

Description:
PRIORITY 
       [0001]    This application claims the benefit under 35 U.S.C. §119(a) of a Korean Patent Application filed in the Korean Intellectual Property Office on Feb. 26, 2007 and assigned Serial No. 2007-19138, the entire disclosure of which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a method and apparatus for providing wireless resources in communication systems. 
         [0004]    2. Description of the Related Art 
         [0005]    As a result of continuing research and development in communication system design, mobile communication systems are evolving. Specifically, standards of the existing systems are being modified to provide higher-speed data services and implementation issues are being solved. For example, the Code Division Multiplex Access (CDMA) system has evolved from CDMA 1x into Evolution Data Only (EV-DO). When evolution between systems is made in this way, various systems having different service levels may coexist such that backward compatibility is necessary with the existing systems. Therefore, a situation may occur in which it is necessary to support both the communication system that was in place before the evolution as well as the communication system that is in place after the evolution. 
         [0006]    As part of the evolution of communication systems, it is also desirable to maximize the capacity of the system. To achieve the capacity maximization while making the evolution, it is necessary not only to modify the system standards but also to use additional frequency bands. 
         [0007]      FIG. 1  illustrates a distribution of frequency bands of a CDMA 1X system and an EV-DO system in a communication system according to the conventional art. 
         [0008]    Referring to  FIG. 1 , the communication system includes a CDMA 1X system and an EV-DO system, both of which use different resources. That is, the CDMA 1X system and the EV-DO system use different frequency bands  100  and  102  independently. The communication system further includes a CDMA 1X system-only terminal  104 , which supports only a band- 1   100  that is an operation frequency band (or service frequency band) of the CDMA 1X system, an EV-DO system-only terminal  108 , which supports only a band- 2   102  that is an operation frequency band of the EV-DO system, and a switching terminal  106 , which supports both the CDMA 1X system and the EV-DO system. 
         [0009]    The phrase ‘switching terminal  106 , which supports both the CDMA 1X system and the EV-DO system’ means that the switching terminal  106  can switch to either of the CDMA 1x system or the EV-DO system rather than simultaneously accessing the two systems to receive service therefrom. 
         [0010]    Similar to the CDMA system described above, it is expected that the IEEE 802.16e system will also experience evolution over time. After such an evolution, the predecessor IEEE 802.16e system may be hereinafter referred to as a ‘legacy system’ and the evolved system can be classified as a system having Backward Compatibility (BC) with the legacy system, which may hereinafter be referred to as a ‘BC system’. 
         [0011]    One service provider, while providing the IEEE 802.16e service using an arbitrary frequency band, can upgrade a legacy system to a BC system for the purpose of performance improvement and to meet the need for capacity increase, and can also build another BC system in another arbitrary frequency band, as shown in  FIGS. 2 and 3 . 
         [0012]      FIG. 2  illustrates a distribution of frequency bands when a legacy system and a system having backward compatibility coexist according to the conventional art. 
         [0013]    Referring to  FIG. 2 , a band- 1   200  is a service frequency band (or operation frequency band) of a legacy system, and a band- 2   202  is a service frequency band of a BC system. In this case, a legacy terminal  204  can perform communication only over band- 1   200 , and a BC terminal  206  can perform communication over both band- 1   200  and band- 2   202 . 
         [0014]      FIG. 3  illustrates a distribution of frequency bands when multiple systems having backward compatibility coexist according to the conventional art. 
         [0015]    Referring to  FIG. 3 , a band- 1   300  is a service frequency band of a BC 1  system and a band- 2   302  is a service frequency band of a BC 2  system. While a legacy terminal  304  can perform communication only over band- 1   300 , a BC terminal  306  can perform communication over both band- 1   300  and band- 2   302 . 
         [0016]      FIG. 4  illustrates a resource allocation method in multiple communication systems according to the conventional art. The multiple communication systems are assumed herein to be IEEE 802.16e systems, by way of example. 
         [0017]    Referring to  FIG. 4 , the conventional IEEE 802.16e system allocates Downlink (DL) resources and Uplink (UL) resources by transmitting MAP Information Element (MAP_IE) information in a DL frame. That is, in a channel using band- 1   400 , the IEEE 802.16e system allocates resources of only band- 1   400  using MAP information  410 . Similarly, in a channel using band- 2   405 , the IEEE 802.16e system allocates resources of only band- 2   405  using MAP information  415 . 
         [0018]    A terminal using a particular frequency band is allocated resources only in that particular frequency band. That is, in  FIG. 1 , the CDMA 1X system-only terminal  104  is allocated resources over band- 1   100 . The switching terminal  106 , when it receives service in band-i  100 , is allocated resources in band- 1   100 , and the switching terminal  106 , when it receives service in band- 2   102 , is allocated resources in band- 2   102 . The EV-DO system-only terminal  108  receives service in band- 2   102 . 
         [0019]    In  FIG. 2 , the legacy terminal  204  is allocated resources in band- 1   200 . The BC terminal  206 , when it receives service in band- 1   200 , is allocated resources in band- 1   200 , and the BC terminal  206 , when it receives service in band- 2   202 , is allocated resources in band- 2   202 . 
         [0020]    In  FIG. 3 , the legacy terminal  304  is allocated resources in band- 1   300 . The BC terminal  306 , when it receives service over band- 1   300 , is allocated resources over band- 1   300 , and the BC terminal  306 , when it receives service over band- 2   302 , is allocated resources over band- 2   302 . 
         [0021]    As described above, in the conventional IEEE 802.16e system, the base station allocates resources only in the frequency band in which the corresponding terminal is receiving service. Therefore, in the case where the base station can broadcast resource allocation information in another arbitrary frequency band but cannot broadcast resource allocation information in the corresponding frequency band, the base station cannot allocate resources in the corresponding frequency band, making it impossible to provide a particular service to the terminal in the corresponding frequency band. 
       SUMMARY OF THE INVENTION 
       [0022]    An aspect of the present invention is 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 a method and apparatus for dynamically allocating wireless resources to a terminal when multiple systems having backward compatibility coexist. 
         [0023]    Another aspect of the present invention is to provide a method and apparatus in which, when multiple systems having backward compatibility coexist, a base station dynamically provides wireless resource allocation information using an arbitrary frequency band independent of the frequency band being used by the terminal, thereby improving utilization efficiency of resources. 
         [0024]    According to one aspect of the present invention, a method for allocating resources in a communication system is provided. The method includes determining a first frequency band for transmitting wireless resource allocation information to a terminal from among frequency bands supporting the communication system, determining at least one second frequency band over which the terminal desires to receive a service, generating wireless resources allocation information for allocation of to the second frequency band and transmitting the wireless resource allocation information to the terminal over the first frequency band. 
         [0025]    According to another aspect of the present invention, a method for receiving wireless resources in a communication system having backward compatibility is provided. The method includes receiving wireless resource allocation information over a first frequency band determined by a base station, determining at least one service frequency band included in the wireless resource allocation information and receiving data over the checked service frequency band. 
         [0026]    According to still another aspect of the present invention, an apparatus for allocating resources in a communication system is provided. The apparatus includes a determiner for determining a first frequency band for transmitting wireless resource allocation information to a terminal from among frequency bands supporting the communication system, a MAP generator for determining at least one second frequency band over which the terminal desires to receive a service and for allocating wireless resources to the second frequency band and a transmission unit for transmitting the wireless resource allocation information to the terminal over the first frequency band. 
         [0027]    According to yet another aspect of the present invention, an apparatus for receiving wireless resources in a communication system having backward compatibility is provided. The apparatus includes a reception unit for receiving wireless resource allocation information over a first frequency band determined by a base station and a MAP information decrypter for determining at least one service frequency band included in the wireless resource allocation information. 
         [0028]    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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0030]      FIG. 1  illustrates distribution of frequency bands of a CDMA 1X system and an EV-DO system in a communication system according to the conventional art; 
           [0031]      FIG. 2  illustrates exemplary distribution of frequency bands when multiple systems having backward compatibility coexist according to the conventional art; 
           [0032]      FIG. 3  illustrates another exemplary distribution of frequency bands when multiple systems having backward compatibility coexist according to the conventional art; 
           [0033]      FIG. 4  illustrates a resource allocation method in multiple communication systems according to the conventional art; 
           [0034]      FIG. 5  illustrates a resource allocation method according to an exemplary embodiment of the present invention; 
           [0035]      FIG. 6  illustrates an operation of a base station according to an exemplary embodiment of the present invention; 
           [0036]      FIG. 7  illustrates an operation of a terminal according to an exemplary embodiment of the present invention; 
           [0037]      FIG. 8  illustrates a structure of a base station according to an exemplary embodiment of the present invention; and 
           [0038]      FIG. 9  illustrates a structure of a terminal according to an exemplary embodiment of the present invention. 
       
    
    
       [0039]    Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features and structures. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0040]    The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and configurations are omitted for clarity and conciseness. 
         [0041]    Exemplary embodiments of the present invention provide a method and apparatus for dynamically allocating wireless resources to a terminal when multiple communication systems having backward compatibility coexist. Although an exemplary description of the present invention will be directed herein with reference to the IEEE 802.16e communication system, this is merely by way of example and the present invention can be applied to other communication systems. A configuration of the IEEE 802.16e communication system includes a base station(s) and a terminal(s). In this configuration, a transmission side can be a base station or a terminal and a reception side can be a terminal or a base station. Although the description will be directed to the case where the base station serves as a transmission side and the terminal serves as a reception side, this is merely by way of example and the same teachings can be applied even to the case where the terminal serves as a transmission side and the base station serves as a reception side. 
         [0042]    Specifically, exemplary embodiments of the present invention provide a method and apparatus in which, when multiple communication systems having backward compatibility coexist, a base station dynamically provides wireless resource allocation information using an arbitrary frequency band independent of the frequency band being used by the terminal, thereby improving utilization efficiency of resources. 
         [0043]      FIG. 5  illustrates a resource allocation method according to an exemplary embodiment of the present invention. 
         [0044]    Referring to  FIG. 5 , in the illustrated example a base station has, as its operation frequency bands, a band- 1   500  and a band- 2   505  each supportable by a legacy system or a BC system. In this case, the base station can allocate DL and UL resources of the band- 1   500  or the band- 2   505 , or can allocate DL and UL resources of both the band- 1   500  and the band- 2   505  using MAP_IE information  510  broadcast in the band- 1   500  regardless of the frequency band being used by the terminal. 
         [0045]    Although not shown, the base station can also allocate DL and UL resources of the band- 1   500  or the band- 2   505 , or can allocate DL and UL resources of both the band- 1   500  and the band- 2   505  using MAP_IE information  515  broadcast in the band- 2   505 . 
         [0046]      FIG. 6  illustrates an operation of a base station according to an exemplary embodiment of the present invention. In the illustrated example, the base station uses a band- 1  and a band- 2  as its service frequency bands. 
         [0047]    Referring to  FIG. 6 , in step  600 , the base station determines a frequency band where it will allocate resources to provide a corresponding service to a terminal. Here, the frequency band where the base station will allocate resources is determined according to the resource condition of the band- 1  and the band- 2 , independent of the frequency band where the terminal desires to receive a service. For sake of example only, it will be assumed herein that the base station has determined to allocate resources to the terminal over the band- 1 . Of course, it must be understood that this is merely an example and that the base station may allocate resources on either of band- 1  or band- 2  or any number of other bands within the control of the base station. 
         [0048]    In step  605 , the base station determines a frequency band in which the terminal desires to receive service. In step  607 , it is determined if the terminal desires to receive service over the same band as the base station has determined for allocation of resources, in this example band- 1 . If the terminal desires to receive service over the same band as determined by the base station for resource allocation, the base station allocates in step  610  resources to the band- 1  using the same MAP_IE( ) of the band- 1  as in the conventional art. If it is determined that the terminal does not desire to receive service on the same band as the resource allocation band of the base station in step  607 , it is determined in step  612  if the terminal desires to receive service over both the band- 1  and the band- 2 . If it is determined that the terminal desires to receive a service over the band- 2  only, that is, the terminal does not desire to receive service over both the band- 1  and the band- 2 , the base station allocates, in the band- 1 , resources to the band- 2  using a new MAP_IE( ) in step  615 . A standard of the new MAP_IE( ) transmitted from the band- 1  depends on the standard of the band- 2 . If it is determined in step  612  that the terminal does desire to receive a service over both the band- 1  and the band- 2 , the base station allocates, in the band- 1 , resources to both the band- 1  and the band- 2  using the new MAP_IE( ) in step  620 . Similarly, a standard of the new MAP_IE( ) transmitted from the band- 1  depends on the standard of the band- 2 . 
         [0049]    Table 1 and Table 2 show formats of DL_MAP_IE( ) and UL_MAP_IE( ) defined to allocate resources to different frequency bands when multiple systems having backward compatibility coexist according to an exemplary embodiment of the present invention, respectively. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 New_DL_MAP_IE 
                 Bits 
                 Notes 
               
               
                   
               
             
             
               
                 Extended-2 DIUC 
                 4 
                   
               
               
                 Length 
                 8 
                 Length in bytes 
               
               
                 Frequency Band Index 
                 4 
                 Index of the band where it is intended 
               
               
                   
                   
                 to provide a service 
               
               
                 DL_MAP_IE( ) 
                 Variable 
                 DL_MAP_IE( ) standard in the band 
               
               
                   
                   
                 where it is intended to provide 
               
               
                   
                   
                 a service 
               
               
                   
               
             
          
         
       
     
         [0050]    Referring to Table 1, a Frequency Band Index field and a DL_MAP_IE( ) field are newly added to the conventional DL_MAP_IE. The Frequency Band Index indicates with  4  bits an index of the band where a DL MAP of the band- 1  intends to provide a service. The Frequency Band Index can indicate either one or both of the band- 1  and the band- 2 . The DL-MAP_IE( ) field indicates a DL_MAP_IE( ) standard of the band where it is intended to provide a service. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 New_UL_MAP_IE 
                 bits 
                 Notes 
               
               
                   
               
             
             
               
                 Extended-2 DIUC 
                 4 
                   
               
               
                 Length 
                 8 
                 Length in bytes 
               
               
                 Frequency Band Index 
                 4 
                 Index of the band where it is intended 
               
               
                   
                   
                 to provide a service 
               
               
                 UL_MAP_IE( ) 
                 variable 
                 UL_MAP_IE( ) standard in the band 
               
               
                   
                   
                 where it is intended to provide 
               
               
                   
                   
                 a service 
               
               
                   
               
             
          
         
       
     
         [0051]    Referring to Table 2, a Frequency Band Index field and a UL_MAP_IE( ) field are newly added to the conventional UL_MAP_IE. The Frequency Band Index indicates with  4  bits an index of the band where a UL MAP of the band- 1  intends to provide a service. The Frequency Band Index can indicate either one or both of the band- 1  and the band- 2 . The UL_MAP_IE( ) field indicates a UL_MAP_IE( ) standard of the band where it is intended to provide a service. 
         [0052]      FIG. 7  illustrates an operation of a terminal according to an exemplary embodiment of the present invention. 
         [0053]    Referring to  FIG. 7 , in step  700 , the terminal decrypts a MAP received from the base station to determine the band over which the base station will transmit/receive data. That is, the terminal determines the corresponding band by evaluating the Frequency Band Index field of the MAP formats shown in Table 1 and Table 2. 
         [0054]    If it is determined the Frequency Band Index indicates band- 1 , the terminal transmits/receives, in step  705 , data of the service provided by band- 1  using the same MAP_IE( ) as the conventional one, which is received in band- 1 . However, if it is determined that the Frequency Band Index indicates band- 2 , the terminal transmits/receives, in step  710 , data of the service provided by the band- 2  using the new MAP_IE( ) defined in Table 1 or Table 2, which is received in band- 1 . However, if it is determined that the Frequency Band Index indicates both band- 1  and band- 2 , the terminal transmits/receives, in step  715 , data of the service provided by both the band- 1  and the band- 2  using the new MAP_IE( ) defined in Table 1 or Table 2, which is received in band- 1 . 
         [0055]      FIG. 8  illustrates a structure of a base station according to an exemplary embodiment of the present invention. Although a base station  800  is assumed herein to use a band- 1  and a band- 2  as its service frequency bands, the present invention can be applied to other communication systems where three or more bands are used. 
         [0056]    Referring to  FIG. 8 , the base station  800  includes a MAP generator  805 , a code modulator  810 , a resource mapper  815 , an Orthogonal Frequency Division Multiplexing (OFDM) modulator  820 , a Digital-to-Analog Converter (DAC)  825 , a Radio Frequency (RF) transmitter  830  associated with each band and a transmit antenna  835 . 
         [0057]    When the base station  800  has data to transmit to the terminal, the MAP generator  805  determines the resource condition of band- 1  and band- 2  to determine the band where it will allocate resources to the terminal. In an exemplary implementation, the MAP generator  805  determines that band- 1  is the frequency band where it will allocate resources to the terminal. 
         [0058]    Thereafter, if the band over which the terminal desires to receive a service is inconsistent with the determined resource allocation band, the MAP generator  805  generates a MAP_IE( ) including a corresponding standard of the band over which the terminal desires to receive service and an indicator indicating the same, and delivers the generated MAP_IE( ) to the code modulator  810 . The MAP generator  805  modulates a DL MAP with the MAP_IE( ) by means of the code modulator  810  and then transfers the modulated DL MAP to the resource mapper  815 . 
         [0059]    Operations of the OFDM modulator  820 , the DAC  825 , the RF transmitter  830  and the transmit antenna  835 , after allocating the DL MAP for transmission data, are substantially the same as conventional operations, so a detailed description thereof will be omitted herein for simplicity. 
         [0060]      FIG. 9  illustrates a structure of a terminal according to an exemplary embodiment of the present invention. Herein, the terminal  900  can transmit/receive data over a band- 1  and a band- 2 . 
         [0061]    Referring to  FIG. 9 , the terminal  900  includes a receive antenna  905 , an RF receiver  910 , a Analog-to-Digital Converter (ADC)  915 , an OFDM demodulator  920 , a MAP extractor  925 , a decoder/demodulator  930  and a MAP information decrypter  935 . 
         [0062]    The RF receiver  910  receives data from the transmission side via the receive antenna  905 , digitally-converts the received data by means of the ADC  915 , and then transfers the digitally-converted data to the MAP extractor  925  by way of the OFDM demodulator  920 . 
         [0063]    The MAP extractor  925  extracts the band where the terminal  900  is allocated resources and the band where it desires to receive a service, from the MAP allocated to the corresponding band over which the RF receiver  910  has received a packet, and then delivers the extracted band information to the MAP information decrypter  935  by way of the decoder/demodulator  930 . 
         [0064]    The MAP information decrypter  935  decrypts the extracted band information to determine whether the resource allocation band is consistent with the band where the terminal  900  desires to receive a service, evaluates a Frequency Band Index field of the MAP and, based on the evaluation, receives corresponding data over the band where the terminal desires to receive a service. The resource allocation band is assumed herein to be band- 1 . In this case, if the frequency band over which the terminal desires to receive a service is band- 1 , the terminal receives data in the conventional method. If the frequency band over which the terminal desires to receive a service is band- 2 , the terminal receives data over band- 2 . If the frequency band over which the terminal desires to receive a service is both band- 1  and band- 2 , the terminal receives data over both band-  1  and band- 2 . 
         [0065]    As is apparent from the foregoing description, according to an exemplary embodiment of the present invention, when multiple communication systems having backward compatibility coexist, the base station dynamically provides wireless resource allocation information using an arbitrary frequency band regardless of the frequency band providing service to the terminal, thereby contributing to an improvement of resource efficiency. 
         [0066]    While the invention has been shown and described with reference to a certain exemplary embodiment 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.