Patent Publication Number: US-2011051784-A1

Title: Relay method and relay apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2009-201737, filed on Sep. 1, 2009, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to a wireless signal relay method and relay apparatus and also to a wireless communication apparatus, mobile station apparatus, and base station apparatus whose transmit signals are relayed using the relay method and relay apparatus. 
     BACKGROUND 
     A method for relaying wireless communication between a base station apparatus and a mobile station apparatus by using a relay apparatus has been implemented in the field of wireless communication. One example of such a relay apparatus is a booster apparatus that does not perform signal regeneration. 
     In the prior art a communication relay apparatus that can enhance throughput by improving the error rate characteristics of a relay destination and can prevent a decrease in the throughput of the entire communication system by reducing interference power has been proposed. This communication relay apparatus receives a signal destined for a base station and performs processing such as decoding. Further, the signal is checked for a bit error, and if there is no bit error, the relay apparatus performs signal regeneration. If there is a bit error, the reception quality of each subcarrier is checked against a threshold value. If the reception quality is not less than the threshold value, the subcarrier is output, but if the reception quality is less than the threshold value, the subcarrier is not relayed to the destination. The signal processed in one or the other way is transmitted out. 
     A relay apparatus that relays without regeneration a signal transmitted from one wireless communication apparatus to another wireless communication apparatus in a wireless communication system constructed from a plurality of wireless communication apparatuses has also been proposed. This relay apparatus is used in a wireless communication system in which, when relaying a signal, a communication channel for relaying the signal is selected from among a plurality of communication channels. The relay apparatus includes a receiving unit which receives a relay frame that carries information concerning the communication channel used by the originating wireless communication apparatus, and a transmitting unit which transmits out the relay frame. 
     A data collection method wherein slave data collection time slots and relay station data collection time slots are provided within a data collection period, and wherein a master station transmits a data request signal at the beginning of the data collection period and a relay station transmits a data request signal by using a relay station data collection time slot has also been proposed. In this method, a slave station that received the data request signal transmits data by randomly selecting a slave data collection time slot. The master station transmits a response acknowledgement signal indicating the slave station from which the data was received. The relay station that received the data from the slave station deletes the data of the slave station indicated by the response acknowledgement signal and, using a relay station data collection time slot, transmits the data received from the slave station but not received yet by the master station. 
     Related art is disclosed in International Publication Pamphlet No. WO2006/118125, Japanese Laid-open Patent Publication No. 2008-79023 and Japanese Laid-open Patent Publication No. 6-334581. 
     SUMMARY 
     A wireless signal relay method according to one mode of the present invention includes: 
     receiving a wireless signal transmitted by mapping a first signal to be relayed in a repetitive manner to a plurality of wireless resources; generating a combined signal by combining signals repetitively mapped as the first signal to be relayed; and transmitting the combined signal. 
     A relay apparatus according to another mode of the present invention includes: a first receiving unit which receives a wireless signal; a combining unit which generates a combined signal by combining signals repetitively mapped as a first signal to be relayed to a plurality of wireless resources and received by the first receiving unit; and a first transmitting unit which transmits the combined signal. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING(S) 
         FIG. 1  is a diagram illustrating the configuration of a first embodiment implemented in a wireless communication system; 
         FIG. 2  is a diagram illustrating a first configuration example of a relay apparatus depicted in  FIG. 1 ; 
         FIG. 3  is a diagram illustrating a first configuration example of a mobile station apparatus depicted in  FIG. 1 ; 
         FIG. 4  is an explanatory diagram illustrating a relay process for a downlink signal; 
         FIG. 5A  is an explanatory diagram illustrating a first example of the downlink signal; 
         FIG. 5B  is an explanatory diagram illustrating a first example of the downlink signal; 
         FIG. 6A  is an explanatory diagram illustrating a second example of the downlink signal; 
         FIG. 6B  is an explanatory diagram illustrating a second example of the downlink signal; 
         FIG. 7  is an explanatory diagram illustrating a relay process for an uplink signal; 
         FIG. 8A  is an explanatory diagram illustrating a first example of the uplink signal; 
         FIG. 8B  is an explanatory diagram illustrating a first example of the uplink signal; 
         FIG. 9A  is an explanatory diagram illustrating a second example of the uplink signal; 
         FIG. 9B  is an explanatory diagram illustrating a second example of the uplink signal; 
         FIG. 10  is a diagram illustrating a configuration example of a base station apparatus depicted in  FIG. 1 ; 
         FIG. 11  is a diagram illustrating a second configuration example of the relay apparatus depicted in  FIG. 1 ; 
         FIG. 12  is a diagram illustrating a third configuration example of the relay apparatus depicted in  FIG. 1 ; 
         FIG. 13  is a diagram illustrating a second configuration example of the mobile station apparatus depicted in  FIG. 1 ; 
         FIG. 14  is a diagram illustrating a fourth configuration example of the relay apparatus depicted in  FIG. 1 ; 
         FIG. 15A  is a diagram illustrating a configuration example of a first mapper; 
         FIG. 15B  is a diagram illustrating a configuration example of a second mapper; 
         FIG. 16  is a diagram illustrating a third configuration example of the mobile station apparatus depicted in  FIG. 1 ; 
         FIG. 17  is a diagram illustrating the configuration of a second embodiment implemented in a wireless communication system; 
         FIG. 18  is a diagram illustrating a first configuration example of the relay apparatus depicted in  FIG. 17 ; 
         FIG. 19A  is an explanatory diagram illustrating a third example of the downlink signal; 
         FIG. 19B  is an explanatory diagram illustrating a third example of the downlink signal; 
         FIG. 19C  is an explanatory diagram illustrating a third example of the downlink signal; 
         FIG. 19D  is an explanatory diagram illustrating a third example of the downlink signal; 
         FIG. 20  is a diagram illustrating a first configuration example of the mobile station apparatus depicted in  FIG. 17 ; 
         FIG. 21A  is an explanatory diagram illustrating a third example of the uplink signal; 
         FIG. 21B  is an explanatory diagram illustrating a third example of the uplink signal; 
         FIG. 21C  is an explanatory diagram illustrating a third example of the uplink signal; 
         FIG. 21D  is an explanatory diagram illustrating a third example of the uplink signal; 
         FIG. 22  is a diagram illustrating a second configuration example of the relay apparatus depicted in  FIG. 17 ; 
         FIG. 23  is a diagram illustrating a second configuration example of the mobile station apparatus depicted in  FIG. 17 ; 
         FIG. 24  is a diagram illustrating the configuration of a third embodiment implemented in a wireless communication system; 
         FIG. 25  is a diagram illustrating a configuration example of the relay apparatus depicted in  FIG. 24 ; 
         FIG. 26  is a diagram illustrating a configuration example of the mobile station apparatus depicted in  FIG. 24 ; 
         FIG. 27  is a diagram illustrating a first configuration example of the base station apparatus depicted in  FIG. 24 ; 
         FIG. 28A  is an explanatory diagram illustrating a fourth example of the downlink signal; 
         FIG. 28B  is an explanatory diagram illustrating a fourth example of the downlink signal; 
         FIG. 28C  is an explanatory diagram illustrating a fourth example of the downlink signal; 
         FIG. 29A  is an explanatory diagram illustrating a fourth example of the downlink signal; 
         FIG. 29B  is an explanatory diagram illustrating a fourth example of the downlink signal; 
         FIG. 29C  is an explanatory diagram illustrating a fourth example of the downlink signal; 
         FIG. 30  is a diagram illustrating a configuration example of an identification information appending unit; 
         FIG. 31  is a diagram illustrating a first configuration example of a relay identifying unit; 
         FIG. 32  is a diagram illustrating a second configuration example of the base station apparatus depicted in  FIG. 24 ; 
         FIG. 33  is a diagram illustrating a second configuration example of the relay identifying unit; 
         FIG. 34  is a diagram illustrating the configuration of a fourth embodiment implemented in a wireless communication system; and 
         FIG. 35  is an explanatory diagram illustrating a scheduling process performed at the base station apparatus depicted in  FIG. 34 ; 
     
    
    
     DESCRIPTION OF EMBODIMENT(S) 
     Embodiments of the present invention will be described below with reference to the accompanying drawings.  FIG. 1  is a diagram illustrating the configuration of a first embodiment implemented in a wireless communication system. Reference numeral  1  indicates the wireless communication system, BS designates a base station apparatus, MS 1  to MS 3  designate mobile station apparatuses, and R designates a relay apparatus. The wireless communication system  1  thus includes the base station apparatus BS, the mobile station apparatuses MS 1  to MS 3 , and the relay apparatus R. The mobile station apparatuses MS 1  to MS 3  may hereinafter be collectively designated as the mobile station apparatus MS. 
     The relay apparatus R relays wireless communication between the base station apparatus BS and the mobile station apparatus MS. For example, the relay apparatus R is used to expand the coverage area so as to cover a dead zone created within the cell served by the base station apparatus BS. The relay apparatus R may be, for example, a booster apparatus that does not perform signal regeneration. In the present embodiment, it is assumed that the mobile station apparatus MS 3  is served by the relay apparatus R. 
     The number of mobile station apparatuses MS located within the coverage area of the relay apparatus R is smaller than the number of mobile station apparatuses MS located within the coverage area of the base station apparatus BS. As a result, in the case of a prior art relay apparatus, unused frequency resources or time slots can occur within its coverage area, resulting in a degradation of utilization of the wireless resources. 
     For example, in the case of a downlink signal, the relay apparatus simply amplifies the wireless signal received from the base station apparatus and transmits it out on the outgoing link. As a result, even when the wireless signal is destined for a mobile station apparatus located outside the coverage area of the relay apparatus, the relay apparatus relays the wireless signal within the coverage area. On the other hand, in the case of an uplink signal, for example, since the wireless resources assigned to mobile station apparatuses located outside the coverage area of the relay apparatus are not used, there occur wireless resources not used within the coverage area of the relay apparatus R. 
     In the present embodiment, the wireless resources used within the coverage area of the relay apparatus R are utilized to enhance communication quality. For this purpose, within the coverage area of the relay apparatus R, in the case of a downlink transmit signal the relay apparatus R transmits the signal to the designated mobile station apparatus by mapping the same signal to be transmitted to a plurality of wireless resources in a repetitive manner. In this case, the mobile station apparatus combines the signals repetitively mapped to the plurality of wireless resources. On the other hand, within the coverage area of the relay apparatus R, in the case of an uplink transmit signal the mobile station apparatus transmits the signal to the relay apparatus R by mapping the same transmit signal to a plurality of wireless resources in a repetitive manner. In this case, the relay apparatus R combines the signals repetitively mapped to the plurality of wireless resources. 
     For example, suppose that the same signal is mapped to the plurality of wireless resources repetitively a number “n” of times. Then, if it is assumed that the propagation path characteristics are the same for the plurality of wireless resources, it is expected that the strength of the amplitude of the combined signal component increases by a factor of “n”, while the strength of the amplitude of the noise component increases by a factor of “√n”. The present embodiment thus improves the quality of communication between the relay apparatus R and the mobile station apparatus MS. 
       FIG. 2  is a diagram illustrating a first configuration example of the relay apparatus R depicted in  FIG. 1 . Reference numerals  10  and  17  are antennas,  11  and  16  are antenna duplexers (DUPs),  12  is a wireless resource information receiving unit, and  13  is a wireless resource information storage unit. Further, reference numeral  14  is a synchronization detection unit,  15  is a mapping unit, and  18  is a combining unit. 
     The relay apparatus R thus includes the antennas  10  and  17 , the antenna duplexers  11  and  16 , the wireless resource information receiving unit  12 , the wireless resource information storage unit  13 , the synchronization detection unit  14 , the mapping unit  15 , and the combining unit  18 . 
     The antenna  10  is an antenna for receiving a signal to be relayed, from the base station apparatus BS, and for transmitting a signal to be relayed to the base station apparatus BS. The signal to be relayed by the relay apparatus R may hereinafter be designated as a relay signal. The signal received by the antenna  10  is transferred via the antenna duplexer  11  into the receiver unit within the relay apparatus R. The antenna  10  and the antenna duplexer  11  here are given as one example of the second receiving unit described in the appended claims. The signal received by the antenna  10  is supplied to the wireless resource information receiving unit  12 , the synchronization detection unit  14 , and the mapping unit  15 . 
     The wireless resource information receiving unit  12  receives wireless resource information transmitted from the base station apparatus BS. The wireless resource information includes information for specifying the plurality of wireless resources to which the signal to be transmitted to the mobile station apparatus M 3  is to be mapped in a repetitive manner in the wireless communication between the relay apparatus R and the mobile station apparatus M 3  served by the relay apparatus R, and information for specifying the plurality of wireless resources to which the signal to be transmitted from the mobile station apparatus M 3  is to be mapped in a repetitive manner. The wireless resource information received by the wireless resource information receiving unit  12  is stored in the wireless resource information storage unit  13 . 
     The synchronization detection unit  14 , based on the signal received from the base station apparatus BS, establishes synchronization with the base station apparatus BS and generates a timing signal that indicates the timing for processing the signal to be relayed. For example, the synchronization detection unit  14  may establish synchronization with the base station apparatus BS by using a pilot signal transmitted from the base station apparatus BS. In accordance with the timing signal generated by the synchronization detection unit  14 , the mapping unit  15  maps the signal to be relayed to the mobile station apparatus M 3  in a repetitive manner to the plurality of wireless resources specified by the wireless resource information stored in the wireless resource information storage unit  13 . 
     The antenna  17  is an antenna for receiving a relay signal from the mobile station apparatus M 3  located within the coverage area of the relay apparatus R, and for transmitting a relay signal to the mobile station apparatus M 3 . The relay signal mapped to the plurality of wireless resources is processed by the signal processing circuit within the relay apparatus R, and is output via the antenna duplexer  16  to the antenna  17  for transmission. The antenna  17  and the antenna duplexer  16  here are given as one example of the second receiving unit described in the appended claims. 
     The signal transmitted from the mobile station apparatus M 3  and received by the antenna  17  is transferred via the antenna duplexer  16  into the receiver unit within the relay apparatus R. The antenna  17  and the antenna duplexer  16  here are given as one example of the first receiving unit described in the appended claims. The signal received by the antenna  17  is supplied to the combining unit  18 . 
     In accordance with the wireless resource information stored in the wireless resource information storage unit  13  and the timing signal generated by the synchronization detection unit  14 , the combining unit  18  combines the signals on the plurality of wireless resources to which the uplink signal transmitted from the mobile station apparatus MS 3  is mapped in a repetitive manner. More specifically, the combining unit  18  sums the signals mapped to the plurality of wireless resources. 
     The combined signal from the combining unit  18  is processed by the signal processing circuit within the relay apparatus R, and is output via the antenna duplexer  11  to the antenna  10  for transmission. The antenna  10  and the antenna duplexer  11  here are given as one example of the first receiving unit described in the appended claims. 
       FIG. 3  is a diagram illustrating a first configuration example of the mobile station apparatus MS depicted in  FIG. 1 . Reference numeral  20  is an antenna,  21  is an antenna duplexer,  22  is a wireless resource information receiving unit,  23  is a wireless resource information storage unit, and  24  is a synchronization detection unit. Further, reference numeral  25  is a combining unit,  26  is a reception processing unit,  27  is a baseband signal processing unit,  28  is a transmission processing unit, and  29  is a mapping unit. 
     The mobile station apparatus MS thus includes the antenna  20 , the antenna duplexer  21 , the wireless resource information receiving unit  22 , the wireless resource information storage unit  23 , and the synchronization detection unit  24 . The mobile station apparatus MS further includes the combining unit  25 , the reception processing unit  26 , the baseband signal processing unit  27 , the transmission processing unit  28 , and the mapping unit  29 . 
     The antenna  20  is an antenna for receiving a downlink signal from the base station apparatus BS, and for transmitting an uplink signal to the base station apparatus BS. The antenna  20  and the antenna duplexer  21  are given as one example of the third receiving unit and third transmitting unit described in the appended claims. The signal received by the antenna  20  is transferred via the antenna duplexer  21  into the receiver unit within the mobile station apparatus MS. The signal received by the antenna  20  is supplied to the combining unit  25  and the synchronization detection unit  24 . 
     The wireless resource information receiving unit  22  takes as input from the baseband signal processing unit  27  the wireless resource information transmitted from the base station apparatus BS and demodulated and decoded by the reception processing unit  26  to be described later. The wireless resource information received by the wireless resource information receiving unit  22  is stored in the wireless resource information storage unit  23 . 
     The synchronization detection unit  24 , based on the signal received from the base station apparatus BS, establishes synchronization with the base station apparatus BS and generates a timing signal that indicates the timing for processing the signal to be relayed. For example, the synchronization detection unit  24  may establish synchronization with the base station apparatus BS by using a pilot signal transmitted from the base station apparatus BS. In accordance with the wireless resource information stored in the wireless resource information storage unit  23  and the timing signal generated by the synchronization detection unit  24 , the combining unit  25  combines the signals on the plurality of wireless resources to which the downlink signal relayed from the relay apparatus R is mapped in a repetitive manner. More specifically, the combining unit  25  sums the signals mapped to the plurality of wireless resources. 
     The reception processing unit  26  demodulates and decodes the downlink signal output from the combining unit  25 . The baseband signal processing unit  27  performs baseband signal processing for the user data and control information transferred between the base station apparatus BS and the mobile station apparatus MS. 
     The transmission processing unit  28  encodes and modulates the uplink signal to be transmitted from the mobile station apparatus MS to the base station apparatus BS. In accordance with the timing signal generated by the synchronization detection unit  24 , the mapping unit  29  maps the uplink signal in a repetitive manner to the plurality of wireless resources specified by the wireless resource information stored in the wireless resource information storage unit  23 . The uplink signal mapped to the plurality of wireless resources is output onto the antenna  20  via the antenna duplexer  21  and transmitted out from the mobile station apparatus MS. 
     Next, the relay process performed by the relay apparatus R will be described.  FIG. 4  is an explanatory diagram illustrating the relay process for the downlink signal. In an alternative embodiment, the following operations AA to AF may be implemented as steps. In operation AA, the relay apparatus R receives the downlink signal transmitted from the base station apparatus BS. 
     In operation AB, the mapping unit  15  creates a signal SC 1  for transmission within the coverage area by mapping the downlink signal destined for the mobile station apparatus MS 3  in a repetitive manner to the plurality of wireless resources specified by the wireless resource information received from the base station apparatus BS. The signal created by mapping the downlink signal to the plurality of wireless resources in a repetitively manner may hereinafter be referred to as the “intra-coverage-area downlink signal.” 
     In operation AC, the relay apparatus R transmits the intra-coverage-area downlink signal SC 1  within the coverage area.  FIG. 5A  depicts a first example of the downlink signal outside the coverage area of the relay apparatus R. The downlink signal is multiplexed by using a time division multiple access technique, and reference numerals  501  to  504  indicate four successive time slots. The time slots  501  and  503  are assigned to the downlink signals S 1  and S 2  destined for the mobile station apparatus MS 3  served by the relay apparatus R. On the other hand, the time slots  502  and  504  are assigned to mobile station apparatus not served by the relay apparatus R. 
       FIG. 5B  depicts an example of the downlink signal within the coverage area of the relay apparatus R. In this example, the wireless resource information specifies the original time slot to which the downlink signal was mapped in the communication between the base station apparatus BS and the mobile station apparatus MS 3  and its immediately succeeding time slot as the plurality of wireless resources to which the downlink signal is to be mapped in a repetitive manner. As a result, the downlink signal S 1  transmitted in the time slot  501  in  FIG. 5A  is mapped by the mapping unit  15  in the relay apparatus R to the time slot  501  and its immediately succeeding time slot  502  in a repetitive manner. Likewise, the downlink signal S 2  transmitted in the time slot  503  in  FIG. 5A  is mapped to the time slot  503  and its immediately succeeding time slot  504  in a repetitive manner. 
       FIG. 6A  depicts a second example of the downlink signal outside the coverage area of the relay apparatus R. The downlink signal is multiplexed by using a frequency division multiple access technique, and reference numerals  511  to  514  indicate four successive frequency resources, i.e., frequency bands. The frequency bands  511  and  513  are assigned to the downlink signals S 1  and S 2  destined for the mobile station apparatus MS 3 . On the other hand, the frequency bands  512  and  514  are assigned to mobile station apparatus not served by the relay apparatus R. 
       FIG. 6B  depicts an example of the downlink signal within the coverage area of the relay apparatus R. In this example, the wireless resource information specifies the original frequency band to which the downlink signal was mapped in the communication between the base station apparatus BS and the mobile station apparatus MS 3  and its adjacent frequency band as the plurality of wireless resources to which the downlink signal is to be mapped in a repetitive manner. As a result, the downlink signal S 1  transmitted in the frequency band  511  in  FIG. 6A  is mapped by the mapping unit  15  in the relay apparatus R to the frequency band  511  and its adjacent frequency band  512  in a repetitive manner. Likewise, the downlink signal S 2  transmitted in the frequency band  513  in  FIG. 6A  is mapped to the frequency band  513  and its adjacent frequency band  514  in a repetitive manner. 
     Reference is made to  FIG. 4 . In operation AD, the mobile station apparatus MS 3  receives the intra-coverage-area downlink signal SC 1 . In operation AE, the combining unit  25  in the mobile station apparatus MS 3  sums the downlink signals mapped to the plurality of wireless resources assigned to the intra-coverage-area downlink signal SC 1 . 
     For example, in the example of the intra-coverage-area downlink signal depicted in  FIG. 5B , the combining unit  25  sums the downlink signals mapped to the time slots  501  and  502 . Further, the combining unit  25  sums the downlink signals mapped to the time slots  503  and  504 . On the other hand, in the example of the intra-coverage-area downlink signal depicted in  FIG. 6B , the combining unit  25  sums the downlink signals mapped to the frequency bands  511  and  512 . Further, the combining unit  25  sums the downlink signals mapped to the frequency bands  513  and  514 . In operation AF, the reception processing unit  26  demodulates and decodes the downlink signal output from the combining unit  25 . 
       FIG. 7  is an explanatory diagram illustrating the relay process for the uplink signal. In an alternative embodiment, the following operations BA to BF may be implemented as steps. In operation BA, the transmission processing unit  28  in the mobile station apparatus MS 3  encodes and modulates the uplink signal to be transmitted from the mobile station apparatus MS 3  to the base station apparatus BS. 
     In operation BB, the mapping unit  29  creates a signal SC 2  for transmission within the coverage area of the relay apparatus R by mapping the uplink signal in a repetitive manner to the plurality of wireless resources specified by the wireless resource information received from the base station apparatus BS. The signal created by mapping the uplink signal to the plurality of wireless resources in a repetitive manner may hereinafter be referred to as the “intra-coverage-area uplink signal.” 
     In operation BC, the mobile station apparatus MS 3  transmits the intra-coverage-area uplink signal SC 2 .  FIG. 8A  depicts a first example of the uplink signal within the coverage area of the relay apparatus R. The uplink signal is multiplexed by using a time division multiple access technique, and reference numerals  521  to  524  indicate four successive time slots. 
     In this example, the wireless resource information specifies the original time slot to which the uplink signal was mapped in the communication between the base station apparatus BS and the mobile station apparatus MS 3  and its immediately preceding time slot as the plurality of wireless resources to which the uplink signal is to be mapped in a repetitive manner. As a result, the uplink signal S 1  is mapped to the two successive time slots  521  and  522 , and the uplink signal S 2  is mapped to the two successive time slots  523  and  524 . 
       FIG. 9A  depicts a second example of the uplink signal within the coverage area of the relay apparatus R. The uplink signal is multiplexed by using a frequency division multiple access technique, and reference numerals  531  to  534  indicate four successive frequency bands. In this example, the wireless resource information specifies the original frequency band to which the uplink signal was mapped in the communication between the base station apparatus BS and the mobile station apparatus MS 3  and its adjacent frequency band as the plurality of wireless resources to which the uplink signal is to be mapped in a repetitive manner. As a result, the uplink signal S 1  is mapped to the two adjacent frequency bands  531  and  532 , and the uplink signal S 2  is mapped to the two successive frequency bands  533  and  534 . 
     Reference is made to  FIG. 7 . In operation BD, the relay apparatus R receives the intra-coverage-area uplink signal SC 2 . In operation BE, the combining unit  18  in the relay apparatus R sums the uplink signals mapped to the plurality of wireless resources assigned to the intra-coverage-area uplink signal SC 2 . 
     For example, in the example of the intra-coverage-area uplink signal depicted in  FIG. 8A , the combining unit  18  sums the uplink signals mapped to the time slots  521  and  522 . Further, the combining unit  18  sums the uplink signals mapped to the time slots  523  and  524 . On the other hand, in the example of the intra-coverage-area uplink signal depicted in  FIG. 9A , the combining unit  18  sums the uplink signals mapped to the frequency bands  531  and  532 . Further, the combining unit  18  sums the uplink signals mapped to the frequency bands  533  and  534 . 
     Reference is made to  FIG. 7 . In operation BF, the relay apparatus R transmits out the uplink signal which contains the signal output from the combining unit  18 .  FIG. 8B  depicts an example of the uplink signal outside the coverage area of the relay apparatus R when the uplink signal depicted in  FIG. 8A  is relayed. The signal S 1  obtained by combining the uplink signals received in the time slots  521  and  522  in a repetitive manner from the mobile station apparatus MS 3  is mapped to the time slot  522 . 
     Likewise, the signal S 2  obtained by combining the uplink signals received in the time slots  523  and  524  in a repetitive manner from the mobile station apparatus MS 3  is mapped to the time slot  524 . The time slots  521  and  523  are assigned to mobile station apparatus not served by the relay apparatus R. 
       FIG. 9B  depicts an example of the uplink signal outside the coverage area of the relay apparatus R when the uplink signal depicted in  FIG. 9A  is relayed. The signal S 1  obtained by combining the uplink signals received in the frequency bands  531  and  532  in a repetitive manner from the mobile station apparatus MS 3  is mapped to the frequency band  531 . Likewise, the signal S 2  obtained by combining the uplink signals received in the frequency bands  533  and  534  in a repetitive manner from the mobile station apparatus MS 3  is mapped to the frequency band  533 . 
     Next, one example of a wireless resource information setting method will be described.  FIG. 10  is a diagram illustrating a configuration example of the base station apparatus BS depicted in  FIG. 1 . Reference numeral  30  is an antenna,  31  is an antenna duplexer,  32  is a wireless communication unit,  33  is a scheduler,  34  is a terminal information storage unit, and  35  is a wireless resource information generating unit. 
     The base station apparatus BS thus includes the antenna  30 , the antenna duplexer  31 , the wireless communication unit  32 , the scheduler  33 , the terminal information storage unit  34 , and the wireless resource information generating unit  35 . The antenna  30  is an antenna for transmitting a wireless signal to the mobile station apparatus MS, and for receiving a wireless signal from the mobile station apparatus MS. The wireless signal received by the antenna  30  is supplied via the antenna duplexer  31  to the wireless communication unit  32 , and the wireless frequency signal output from the wireless communication unit  32  is supplied via the antenna duplexer  31  to the antenna  30  and transmitted out as a wireless signal. 
     The wireless communication unit  32  performs processing for the reception and transmission of the user data and control information transferred between the mobile station apparatus MS and the base station apparatus BS. The scheduler performs processing for the assignment of wireless resources and the determination of the transmission format for the communication performed between the mobile station apparatus MS and the base station apparatus BS. 
     The terminal information storage unit  34  stores information about the mobile station apparatus MS that is currently connected to the base station apparatus BS and for which the wireless resources used for the wireless communication with the base station apparatus BS are determined by the scheduler  33 . The terminal information storage unit  34  further stores information identifying whether any one of the currently connected mobile station apparatus MS is to be served by the relay apparatus R. 
     The scheduler  33  determines, for each mobile station apparatus MS to be served by the relay apparatus R, the plurality of wireless resources to which the downlink signal is to be mapped in a repetitive manner within the coverage area of the relay apparatus R. Further, the scheduler  33  determines, for each mobile station apparatus MS to be served by the relay apparatus R, the plurality of wireless resources to which the uplink signal is to be mapped in a repetitive manner within the coverage area of the relay apparatus R. 
     The wireless resource information generating unit  35  generates wireless resource information that specifies the plurality of wireless resources determined by the scheduler  33  as the wireless resources to which the downlink or the uplink signal is to be mapped in a repetitive manner within the coverage area of the relay apparatus R. The wireless communication unit  32  transmits the wireless resource information to the mobile station apparatus MS together with the scheduling information indicating the transmission format and the wireless resources assigned to the mobile station apparatus MS. The wireless communication unit  32  also transmits the wireless resource information to the relay apparatus R. 
     The scheduler  33  may determine the wireless resources to be assigned to the plurality of mobile station apparatus MS, in such a manner that the downlink or the uplink signal can be mapped in a repetitive manner to a plurality of temporally or spatially succeeding wireless resources within the coverage area of the relay apparatus R. For this purpose, the scheduler  33  may, for example, determine the assignment of the wireless resources in such a manner that the wireless resources respectively assigned to the plurality of mobile station apparatus MS served by the same relay apparatus R are not adjacent to one another. 
     By thus mapping the same signal to a plurality of adjacent wireless resources, the transmission characteristics of the transmission channels realized by the wireless resources assigned to the signal can be made close to each other. Since the signals to be combined in the receiver apparatus become close to each other in characteristics by repetitively transmitting the same signal over the transmission channels whose characteristics are close to each other, it can be expected that the reception quality further improves when the signals are combined. 
     According to the present invention, the same signal is transmitted in a repetitive manner by using a plurality of wireless resources between the relay apparatus R and the mobile station apparatus MS, and the signals repetitively received at the receiving end are combined. This serves to improve the signal to noise ratio in the communication between the relay apparatus R and the mobile station apparatus MS. 
     Next, another embodiment of the relay apparatus R will be described. For example, in the above-described relay apparatus constructed from a booster apparatus or the like, the received wireless signal is first amplified by an amplifier to a prescribed level, and then the amplified signal is transmitted out. As a result, the relay apparatus transmits not only the signal component of the received wireless signal, but also any noise that occurred within the amplifier in the relay apparatus. If there are a plurality of relay apparatuses within the coverage area of the base station apparatus, noise components output from the plurality of relay apparatuses are added up, resulting in a reduction of channel capacity. 
     In uplink transmission, the present embodiment disables signal output on any wireless resource other than the resources used to transmit to the base station apparatus BS the uplink signal of the mobile station apparatus MS located within the coverage area of the relay apparatus R.  FIG. 11  is a diagram illustrating a second configuration example of the relay apparatus R depicted in  FIG. 1 . 
     Reference numeral  19  designates a disabling unit. That is, the relay apparatus R includes the disabling unit  19 . The same component elements as those of the relay apparatus R depicted in  FIG. 2  are designated by the same reference numerals. Based on the timing signal generated by the synchronization detection unit  14 , the disabling unit  19  controls the wireless resources onto which signals are output from the antenna  10 . That is, the disabling unit  19  disables signal output on any wireless resource other than the wireless resources used to transmit the uplink signal of the mobile station apparatus MS served by the relay apparatus. 
     For example, in the uplink signals depicted in  FIG. 8B , the disabling unit  19  disables the output of the antenna  10  in the time slots  521  and  523 , i.e., the time slots other than the time slots  522  and  524  used to transmit the uplink signal of the mobile station apparatus MS 3 . Further, in the uplink signals depicted in  FIG. 9B , for example, the disabling unit  19  disables the output of subcarriers in the frequency bands  532  and  534 , i.e., the frequency bands other than the frequency bands  531  and  533  used to transmit the uplink signal of the mobile station apparatus MS 3 . 
     The present embodiment thus reduces the noise output from the relay apparatus R. This serves to prevent the noise from the plurality of relay apparatuses from increasing and leading to a reduction in channel capacity. 
     Next, a description will be given of an embodiment implemented in a communication system employing a time division multiple access scheme.  FIG. 12  is a diagram illustrating a third configuration example of the relay apparatus R depicted in  FIG. 1 . Reference numerals  40  and  42  are low-noise amplifiers,  41  and  43  are high-power amplifiers,  44  and  46  are buffers,  45  and  48  are switches, and  47  is an adder. 
     The relay apparatus R thus includes the low-noise amplifiers  40  and  42 , the high-power amplifiers  41  and  43 , the buffers  44  and  46 , the switches  45  and  48 , and the adder  47 . The same component elements as those of the relay apparatus R depicted in  FIG. 11  are designated by the same reference numerals. 
     The low-noise amplifier  40  amplifies the signal received via the antenna  10  and the antenna duplexer  11  from the base station apparatus BS. The high-power amplifier  41  amplifies the signal to be transmitted via the antenna duplexer  16  and the antenna  17  to the mobile station apparatus MS 3 . The low-noise amplifier  42  amplifies the signal received via the antenna  17  and the antenna duplexer  16  from the mobile station apparatus MS 3 . The high-power amplifier  43  amplifies the signal to be transmitted via the antenna duplexer  11  and the antenna  10  to the base station apparatus BS. In the actual configuration, the low-noise amplifiers  40  and  42  are each followed by an analog-digital converter, and the high-power amplifiers  41  and  43  are each preceded by a digital-analog converter, but these converters are not depicted or described for simplicity of illustration. The same applies for other embodiments. 
     The buffer  44  stores the downlink signal to be relayed to the designated mobile station apparatus MS 3 . The switch  45  is used to select the input to the high-power amplifier  41  in accordance with the timing signal generated by the synchronization detection unit  14 . More specifically, during the period that the downlink signal destined for the mobile station apparatus MS 3  is being received, the switch  45  operates to supply the signal received by the antenna  10  to the high-power amplifier  41 . On the other hand, in the time slot specified by the wireless resource information to retransmit the same downlink signal, the switch  45  operates to supply the downlink signal stored in the buffer  44  to the high-power amplifier  41 . 
     By such operation of the switch  45 , the downlink signal destined for the mobile station apparatus MS 3  is transmitted in a repetitive manner by using a plurality of time slots. That is, the downlink signal is mapped to a plurality of wireless resources. Thus, the buffer  44  and the switch  45  are given as one example of the mapping unit  15  in the relay apparatus R depicted in  FIG. 11 . 
     The buffer  46  stores the uplink signal received from the designated mobile station apparatus MS 3 . The adder  47  adds the unlink signal stored in the buffer  46  to the same unlink signal received in the immediately succeeding time slot, and thus combines the signals. The buffer  46  and the adder  47  are given as one example of the combining unit  18  in the relay apparatus R depicted in  FIG. 11 . 
     When transmitting the uplink signal of the mobile station apparatus MS 3  to the base station apparatus BS, the switch  48  operates to connect the output of the adder  47  to the high-power amplifier  43 . At other times, signal input to the high-power amplifier  43  is disabled. The switch  48  thus operates to disable the relay apparatus R from outputting any uplink signal, except when transmitting the uplink signal of the designated mobile station apparatus MS 3 . Thus, the switch  48  is given as one example of the disabling unit  19  in the relay apparatus R depicted in  FIG. 11 . 
       FIG. 13  is a diagram illustrating a second configuration example of the mobile station apparatus MS depicted in  FIG. 1 . Reference numerals  50  and  53  are buffers,  51  is an adder, and  52  and  54  are switches. The mobile station apparatus MS thus includes the buffers  50  and  53 , the adder  51 , and the switches  52  and  54 . The same component elements as those of the mobile station apparatus MS depicted in  FIG. 3  are designated by the same reference numerals. In the actual configuration, an analog-digital converter is placed between the antenna duplexer  21  and the buffer  50 , and a digital-analog converter is placed between the switch  54  and the antenna duplexer  21 , but these converters are not depicted or described for simplicity of illustration. 
     The buffer  50  stores the downlink signal received from the relay apparatus R. The adder  51  adds the downlink signal stored in the buffer  50  to the same downlink signal received in the immediately succeeding time slot, and thus combines the signals. The switch  52  operates to couple the downlink signal, output from the adder  51 , to the input of the reception processing unit  26  in accordance with the timing signal output from the synchronization detection unit  24 . Thus, the buffer  50 , the adder  51 , and the switch  52  are given as one example of the combining unit  25  in the mobile station apparatus MS depicted in  FIG. 3 . 
     The buffer  53  stores the uplink signal to be transmitted to the relay apparatus R. The switch  54  is used to select the signal to be supplied to the antenna  20  in accordance with the timing signal generated by the synchronization detection unit  24 . More specifically, in the first time slot used to transmit the uplink signal from the mobile station apparatus MS 3  to the relay apparatus R, the switch  54  operates to supply the signal output from the transmission processing unit  28  to the antenna  20 . On the other hand, in the time slot specified by the wireless resource information to retransmit the same uplink signal, the switch  54  operates to supply the uplink signal stored in the buffer  53  to the antenna  20 . Thus, the buffer  53  and the switch  54  are given as one example of the mapping unit  29  in the mobile station apparatus MS depicted in  FIG. 3 . 
     According to the present invention, in a communication system employing a time division multiple access scheme, the signal to noise ratio can be improved in the communication between the relay apparatus R and the mobile station apparatus MS by repetitively transmitting signals using a plurality of wireless resources between the relay apparatus R and the mobile station apparatus MS. 
     Next, a description will be given of an embodiment implemented in a communication system employing an orthogonal frequency division multiple access (OFDMA) scheme as one example of a frequency division multiple access scheme.  FIG. 14  is a diagram illustrating a fourth configuration example of the relay apparatus R depicted in  FIG. 1 . Reference numerals  60  and  63  each designate a fast Fourier transform (FFT) unit, and  61  designates a first mapper. Further, reference numerals  62  and  65  each designate an inverse fast Fourier transform (IFFT) unit, and  64  designates a second mapper. 
     The relay apparatus R thus includes the fast Fourier transform units  60  and  63 , the first and second mappers  61  and  64 , and the inverse fast Fourier transform units  62  and  65 . The same component elements as those of the relay apparatus R depicted in  FIG. 11  are designated by the same reference numerals. In the actual configuration, the inverse fast Fourier transform units  62  and  65  are each followed by a cyclic prefix (CP) adding unit, which is not depicted or described for simplicity of illustration. The same applies for other embodiments. 
     The synchronization detection unit  14  supplies a timing signal for symbol timing synchronization to the fast Fourier transform units  60  and  63 , the first and second mappers  61  and  64 , and the inverse fast Fourier transform units  62  and  65 . The fast Fourier transform unit  60  Fourier-transforms the OFDM (Orthogonal Frequency Division Multiple) signal received from the base station apparatus BS and thereby extracts a complex symbol sequence modulating the plurality of subcarriers. The inverse fast Fourier transform unit  62  regenerates the OFDM signal by modulating the plurality of subcarriers with the complex symbol sequence. The regenerated OFDM signal is amplified by the high-power amplifier  41  and output on the antenna  17  for transmission. 
     The complex symbols output from the fast Fourier transform unit  60  are supplied to the inverse fast Fourier transform unit  62 . The first mapper  61  performs mapping between the complex symbols output from the fast Fourier transform unit  60  and the complex symbols that the inverse fast Fourier transform unit  62  uses to modulate the respective subcarriers. The first mapper  61  may perform the mapping so that the plurality of subcarriers specified by the wireless resource information as the subcarriers for transmitting the downlink signal to the designated mobile station apparatus MS 3  will be modulated by the complex symbols contained in the downlink signal to be relayed to the mobile station apparatus MS 3 . 
       FIG. 15A  is a diagram illustrating a configuration example of the first mapper  61 . The complex symbols respectively modulating the plurality of subcarriers SC 1  to SC 10  are output from the fast Fourier transform unit  60 . The first mapper  61  identifies the complex symbol modulating the subcarrier SC 1  assigned to the mobile station apparatus MS served by the relay apparatus R, and supplies it to the inverse fast Fourier transform unit  62  as the complex symbol to modulate the plurality of subcarriers SC 1  and SC 2 . Likewise, the first mapper  61  identifies the complex symbol modulating the subcarrier SC 3  assigned to the mobile station apparatus MS served by the relay apparatus R, and supplies it to the inverse fast Fourier transform unit  62  as the complex symbol to modulate the plurality of subcarriers SC 3  and SC 4 . The same processing is repeated for each of the other subcarriers SC 5 , SC 7 , and SC 9  assigned to the mobile station apparatus MS served by the relay apparatus R. 
     With such mapping, the downlink signal destined for the mobile station apparatus MS 3  is transmitted in a repetitive manner by using a plurality of frequency bands. That is, the downlink signal is mapped to the plurality of wireless resources. Thus, the fast Fourier transform unit  60 , the first mapper  61 , and the inverse fast Fourier transform unit  62  are given as one example of the mapping unit  15  in the relay apparatus R depicted in  FIG. 11 . 
     Reference is made to  FIG. 14 . The fast Fourier transform unit  63  Fourier-transforms the OFDM signal received from the mobile station apparatus MS 3  and thereby extracts a complex symbol sequence modulating the plurality of subcarriers. The inverse fast Fourier transform unit  65  regenerates the OFDM signal by modulating the plurality of subcarriers with the complex symbol sequence. The regenerated OFDM signal is amplified by the high-power amplifier  43  and output on the antenna  10  for transmission. 
     The complex symbols output from the fast Fourier transform unit  63  are supplied to the inverse fast Fourier transform unit  65 . The second mapper  64  performs mapping between the complex symbols output from the fast Fourier transform unit  63  and the complex symbols that the inverse fast Fourier transform unit  65  uses to modulate the respective subcarriers. 
     The second mapper  64  combines the complex symbols respectively modulating the plurality of subcarriers specified by the wireless resource information as the subcarriers for transmitting the uplink signal from the mobile station apparatus MS 3  served by the relay apparatus R. The second mapper  64  maps the symbols to be supplied to the inverse fast Fourier transform unit  65  so that the subcarriers assigned to transmit the uplink signal of the mobile station apparatus MS 3  from the relay apparatus R will be modulated by the respectively combined symbols. 
       FIG. 15B  is a diagram illustrating a configuration example of the second mapper  64 . The second mapper  64  includes adders  70  to  74  for respectively combining the complex symbols extracted from the plurality of subcarriers. The complex symbols respectively modulating the plurality of subcarriers SC 1  to SC 10  are output from the fast Fourier transform unit  63 . 
     The adder  70  adds together the complex symbols respectively modulating the plurality of subcarriers SC 1  and SC 2  specified by the wireless resource information as the subcarriers for transmitting the uplink signal from the mobile station apparatus MS served by the relay apparatus R. The second mapper  64  supplies the complex symbol output from the adder  70  to the inverse fast Fourier transform unit  65  as the complex symbol to modulate the subcarrier SC 1 . Likewise, the adder  71  adds together the complex symbols respectively modulating the plurality of subcarriers SC 3  and SC 4  specified by the wireless resource information. The second mapper  64  supplies the complex symbol output from the adder  71  to the inverse fast Fourier transform unit  65  as the complex symbol to modulate the subcarrier SC 3 . The same processing is repeated for each of the other subcarrier pairs, SC 5  and SC 6 , SC 7  and SC 8 , and SC 9  and SC 10 , specified by the wireless resource information. 
     With such mapping, the fast Fourier transform unit  63 , the second mapper  64 , and the inverse fast Fourier transform unit  65  combine the uplink signals transmitted from the mobile station apparatus MS 3  in a repetitive manner by using the plurality of carriers. Thus, the fast Fourier transform unit  63 , the second mapper  64 , and the inverse fast Fourier transform unit  65  are given as one example of the combining unit  18  in the relay apparatus R depicted in  FIG. 11 . 
     Further, the second mapper  64  supplies “0” to the inverse fast Fourier transform unit  65  as the symbol for modulating the subcarriers SC 2 , SC 4 , SC 6 , SC 8 , and SC 10  that are not used to transmit the uplink signal to the base station apparatus BS. As a result, these subcarrier components are not output from the relay apparatus R. The second mapper  64  here is given as one example of the disabling unit  19  in the relay apparatus R depicted in  FIG. 11 . 
       FIG. 16  is a diagram illustrating a third configuration example of the mobile station apparatus MS depicted in  FIG. 1 . Reference numeral  80  designates a fast Fourier transform unit, and  81  designates a first mapper. Further, reference numeral  83  designates a second mapper, and  84  designates an inverse fast Fourier transform unit. The mobile station apparatus MS thus includes the fast Fourier transform unit  80 , the first and second mappers  81  and  83 , and the inverse fast Fourier transform unit  84 . The same component elements as those of the mobile station apparatus MS depicted in  FIG. 3  are designated with the same reference numerals. In the actual configuration, an analog-digital converter is placed between the antenna duplexer  21  and the fast Fourier transform unit  80 , and a digital-analog converter is placed between the inverse fast Fourier transform unit  84  and the antenna duplexer  21 , but these converters are not depicted or described for simplicity of illustration. Further, in the actual configuration, the inverse fast Fourier transform unit  84  is followed by a cyclic prefix (CP) adding unit, which is not depicted or described for simplicity of illustration. 
     The synchronization detection unit  24  supplies a timing signal for symbol timing synchronization to the fast Fourier transform unit  80 , the first and second mappers  81  and  83 , and the inverse fast Fourier transform unit  84 . The fast Fourier transform unit  80  Fourier-transforms the OFDM signal received from the relay apparatus R and thereby extracts a complex symbol sequence modulating the plurality of subcarriers. The reception processing unit  26  demodulates and decodes the complex symbol sequence extracted by the fast Fourier transform unit  80 . 
     The first mapper  81  performs mapping between the complex symbols output from the fast Fourier transform unit  80  and the complex symbols to be demodulated and decoded by the reception processing unit  26 . The first mapper  81  combines the complex symbols respectively modulating the plurality of subcarriers specified by the wireless resource information as the subcarriers for transmitting the downlink signal from the relay apparatus R. The first mapper  81  supplies the respectively combined symbols to the reception processing unit  26  as the complex symbols to be demodulated and decoded. The configuration of the first mapper  81  may be the same as that of the second mapper  64  depicted in  FIG. 15B . The fast Fourier transform unit  80  and the first mapper  81  are given as one example of the combining unit  25  in the mobile station apparatus MS depicted in  FIG. 3 . 
     The inverse fast Fourier transform unit  84  generates the OFDM signal by modulating the plurality of subcarriers with the complex symbol sequence supplied from the transmission processing unit  28 . The generated OFDM signal is fed via the antenna duplexer  21  to the antenna  20  for transmission. 
     The second mapper  83  performs mapping between the complex symbols output from the transmission processing unit  28  and the complex symbols that the inverse fast Fourier transform unit  84  uses to modulate the respective subcarriers. The second mapper  83  may perform the mapping so that the plurality of subcarriers specified by the wireless resource information as the subcarriers for transmitting the uplink signal from the mobile station apparatus MS 3  will be modulated by the complex symbols contained in the uplink signal to be transmitted from the mobile station apparatus MS 3 . The configuration of the second mapper  83  may be the same as that of the first mapper  61  depicted in  FIG. 15A . The second mapper  83  and the inverse fast Fourier transform unit  84  are given as one example of the mapping unit  29  in the mobile station apparatus MS depicted in  FIG. 3 . 
     According to the present invention, in a communication system employing an orthogonal frequency division multiple access scheme, the signal to noise ratio can be improved in the communication between the relay apparatus R and the mobile station apparatus MS by repetitively transmitting signals using a plurality of wireless resources between the relay apparatus R and the mobile station apparatus MS. 
     The configurations of the relay apparatus R depicted in  FIGS. 12 and 14  may be combined together, and further, the configurations of the mobile station apparatus MS depicted in  FIGS. 13 and 16  may also be combined together. By thus combining the configuration for implementing the time division multiple access scheme with the configuration for implementing the orthogonal frequency division multiple access scheme, the same signal may be mapped in a repetitive manner to a plurality of time slots and a plurality of frequency resources between the relay apparatus R and the mobile station apparatus MS. 
       FIG. 17  is a diagram illustrating the configuration of a second embodiment implemented in a wireless communication system  1 . Reference numerals R 1  and R 2  designate relay apparatuses. The relay apparatuses R 1  and R 2  may be collectively designated as the relay apparatus R. In the present embodiment, the plurality of relay apparatuses R 1  and R 2  are provided in the wireless communication system  1 . The same component elements as those of the wireless communication system  1  depicted in  FIG. 1  are designated by the same reference numerals. In the present embodiment, it is assumed that the mobile station apparatus MS 2  is served by the relay apparatus R 1  and the mobile station apparatus MS 3  by the relay apparatus R 2 . 
     In the present embodiment, unique orthogonal codes are assigned to the respective relay apparatuses R 1  and R 2  so that interference does not occur between the wireless signal transmitted/received by the relay apparatus R 1  and the wireless signal transmitted/received by the relay apparatus R 2  even if the coverage areas of the relay apparatuses R 1  and R 2  overlap each other. In each of the coverage areas of the relay apparatuses R 1  and R 2 , signals repetitively mapped to a plurality of wireless resources are transmitted by multiplying the signals with the corresponding bits contained in the orthogonal code, thereby reducing interference between the relay apparatuses. 
       FIG. 18  is a diagram illustrating a first configuration example of the relay apparatus R depicted in  FIG. 17 . Reference numeral  90  designates an orthogonal code generating unit, and  91  and  92  each designate a multiplier. The relay apparatus R thus includes the orthogonal code generating unit  90  and the multipliers  91  and  92 . The same component elements as those of the relay apparatus R depicted in  FIG. 12  are designated by the same reference numerals. 
     The orthogonal code generating unit  90  generates an orthogonal code unique to the relay apparatus R with timing defined by the timing signal generated by the synchronization detection unit  14 . The orthogonal code generated here may, for example, be a Walsh code or a Hadamard code. In the illustrated example, it is assumed that a code “1, 1” and a code “1, −1” are assigned as the orthogonal codes to the respective relay apparatuses R 1  and R 2  depicted in  FIG. 17 . 
     In the multiplier  91 , downlink signals repetitively mapped to a plurality of time slots by using the buffer  44  and switch  45  are multiplied with the orthogonal code. More specifically, in the multiplier  91 , downlink signals repetitively mapped to a plurality of time slots are each multiplied with a corresponding one of the bits contained in the orthogonal code. 
     Suppose, for example, that the same downlink signal has been mapped in a repetitively manner to two time slots. Then, in the relay apparatus R 1 , the multiplier  91  multiplies the downlink signals mapped to the first time slot and the second time slot, respectively, with the first bit “1” and the second bit “1” contained in the orthogonal code. Likewise, in the relay apparatus R 2 , the multiplier  91  multiplies the downlink signals mapped to the first time slot and the second time slot, respectively, with the first bit “1” and the second bit “−1” contained in the orthogonal code. 
       FIG. 19A  depicts an example of the downlink signal outside the coverage area of the relay apparatus R 1 . Reference numerals  541  to  544  indicate four successive time slots. The time slots  541  and  543  are assigned to the downlink signals S 11  and S 12  destined for the mobile station apparatus MS 2  served by the relay apparatus R 1 . On the other hand, the time slots  542  and  544  are assigned to mobile station apparatuses not served by the relay apparatus R 1 . 
       FIG. 19B  depicts an example of the downlink signal within the coverage area of the relay apparatus R 1 . In this example, the downlink signal S 11  transmitted in the time slot  541  in  FIG. 9A  is mapped to the time slot  541  and its immediately succeeding time slot  542  in a repetitive manner. Likewise, the downlink signal S 12  transmitted in the time slot  543  in  FIG. 9A  is mapped to the time slot  543  and its immediately succeeding time slot  544  in a repetitive manner. 
     The downlink signals S 11  mapped to the successive time slots  541  and  542  are respectively multiplied with the first bit “1” and the second bit “1” of the orthogonal code. Likewise, the downlink signals S 12  mapped to the successive time slots  543  and  544  are respectively multiplied with the first bit “1” and the second bit “1” of the orthogonal code. 
       FIG. 19C  depicts an example of the downlink signal outside the coverage area of the relay apparatus R 2 . Reference numerals  551  to  554  indicate four successive time slots. The time slots  551  and  553  are assigned to the downlink signals S 21  and S 22  destined for the mobile station apparatus MS 3  served by the relay apparatus R 2 . On the other hand, the time slots  552  and  554  are assigned to mobile station apparatuses not served by the relay apparatus R 2 . 
       FIG. 19D  depicts an example of the downlink signal within the coverage area of the relay apparatus R 2 . In this example, the downlink signal S 21  transmitted in the time slot  551  in  FIG. 9C  is mapped to the time slot  551  and its immediately succeeding time slot  552  in a repetitive manner. The downlink signal S 22  transmitted in the time slot  553  in  FIG. 9C  is mapped to the time slot  553  and its immediately succeeding time slot  554  in a repetitive manner. 
     The downlink signals S 21  mapped to the successive time slots  551  and  552  are respectively multiplied with the first bit “1” and the second bit “−1” of the orthogonal code. As a result, the signal −S 21  to be transmitted in the time slot  552  is an inverted version of the signal S 21  to be transmitted in the time slot  551 . Likewise, the downlink signals S 22  mapped to the successive time slots  553  and  554  are respectively multiplied with the first bit “1” and the second bit “−1” of the orthogonal code. As a result, the signal −S 22  to be transmitted in the time slot  554  is an inverted version of the signal S 22  to be transmitted in the time slot  553 . 
     Reference is made to  FIG. 18 . When transmitting an uplink signal, the mobile station apparatus MS served by the relay apparatus maps the signal to a plurality of time slots and multiplies the thus mapped signal with an orthogonal code as will be described later. When the uplink signal from the mobile station apparatus MS is received, the multiplier  92  multiplies the received signal with the orthogonal code unique to the relay apparatus R. The uplink signals mapped to the plurality of time slots and multiplied by the multiplier  92  with the orthogonal code are combined together by using the buffer  46  and the adder  47 . If the orthogonal code multiplied on the uplink signal in the mobile station apparatus MS is identical to the orthogonal code unique to the relay apparatus R, the original uplink signal is regenerated by the combining operation performed by the buffer  46  and the adder  47 . 
     If the orthogonal code multiplied on the uplink signal is not identical to the orthogonal code unique to the relay apparatus R, the signal component resulting from the combining operation performed by the buffer  46  and the adder  47  is “0”. In this way, any signal received from mobile station apparatus MS served by another relay apparatus is prevented from interfering with the signal received from the mobile station apparatus MS served by the relay apparatus R. 
       FIG. 20  is a diagram illustrating a first configuration example of the mobile station apparatus MS depicted in  FIG. 17 . Reference numeral  93  designates an orthogonal code detection unit, and  94  and  95  each designate a multiplier. The mobile station apparatus MS thus includes the orthogonal code detection unit  93  and the multipliers  94  and  95 . The same component elements as those of the mobile station apparatus MS depicted in  FIG. 13  are designated by the same reference numerals. In the actual configuration, an analog-digital converter is placed between the antenna duplexer  21  and the multiplier  94 , and a digital-analog converter is placed between the multiplier  95  and the antenna duplexer  21 , but these converters are not depicted or described for simplicity of illustration. 
     The orthogonal code detection unit  93  detects the orthogonal code multiplied on the downlink signal mapped in a repetitive manner to the plurality of time slots of the received signal. For example, the orthogonal code detection unit  93  may multiply the downlink signal with each of a plurality of possible orthogonal codes expected to be assigned to the relay apparatus R, and may determine that the orthogonal code detected when a signal strength exceeding a predetermine threshold value is detected is the orthogonal code multiplied on the downlink signal. 
     In the multiplier  94 , the downlink signal mapped in a repetitive manner to the plurality of time slots of the received signal is multiplied with the detected orthogonal code. The original downlink signal is regenerated by the buffer  50  and the adder  51  by combining the downlink signals respectively mapped to the plurality of time slots and multiplied by the orthogonal code. 
     If a signal relayed by some other relay apparatus than the relay apparatus R serving the mobile station apparatus MS is received, the signal component received from such other relay apparatus becomes “0” as a result of the combining operation performed by the buffer  50  and the adder  51 . In this way, any signal transmitted from another relay apparatus is prevented from interfering with the downlink signal being received by the mobile station apparatus MS. 
     In the multiplier  95 , the uplink signal mapped in a repetitive manner to the plurality of time slots by means of the buffer  53  and the switch  54  is multiplied with the orthogonal code detected by the orthogonal code detection unit  93 . The uplink signal multiplied with the orthogonal code is transmitted from the antenna  20  to the relay apparatus R. 
       FIG. 21A  depicts an example of the uplink signal within the coverage area of the relay apparatus R 1 . Reference numerals  561  to  564  indicate four successive time slots. The uplink signal S 11  is mapped to the time slot  561  and its immediately succeeding time slot  562  in a repetitive manner. Likewise, the uplink signal S 12  is mapped to the time slot  563  and its immediately succeeding time slot  564  in a repetitive manner. 
     The uplink signals S 11  mapped to the successive time slots  561  and  562  are respectively multiplied with the first bit “1” and the second bit “1” of the orthogonal code unique to the relay apparatus R 1 . Likewise, the uplink signals S 12  mapped to the successive time slots  563  and  564  are respectively multiplied with the first bit “1” and the second bit “1” of the orthogonal code. 
     When the uplink signals depicted in  FIG. 21A  are received by the relay apparatus R 1 , the multiplier  92  in the relay apparatus R 1  multiplies the received uplink signals with the orthogonal code “1, 1” unique to the relay apparatus R. When the uplink signals multiplied with the orthogonal code are combined using the buffer  46  and the adder  47 , the original uplink signal is regenerated. 
       FIG. 21B  depicts an example of the uplink signal outside the coverage area of the relay apparatus R 1  that relays the uplink signals of  FIG. 21A . The original uplink signals S 11  and S 12  are transmitted in the time slots  562  and  564 , respectively. The time slots  561  and  562  are assigned to mobile station apparatuses not served by the relay apparatus R 1 . 
       FIG. 21C  depicts an example of the uplink signal within the coverage area of the relay apparatus R 2 . Reference numerals  571  to  574  indicate four successive time slots. The uplink signal S 21  is mapped to the time slot  571  and its immediately succeeding time slot  572  in a repetitive manner. The uplink signal S 22  is mapped to the time slot  573  and its immediately succeeding time slot  574  in a repetitive manner. 
     The uplink signals S 21  mapped to the successive time slots  571  and  572  are respectively multiplied with the first bit “1” and the second bit “−1” of the orthogonal code unique to the relay apparatus R 2 . As a result, the signal −S 21  to be transmitted in the time slot  572  is an inverted version of the signal S 21  to be transmitted in the time slot  571 . 
     Likewise, the uplink signals S 22  mapped to the successive time slots  573  and  574  are respectively multiplied with the first bit “1” and the second bit “−1” of the orthogonal code. As a result, the signal −S 22  to be transmitted in the time slot  574  is an inverted version of the signal S 22  to be transmitted in the time slot  573 . 
     When the uplink signals depicted in  FIG. 21C  are received by the relay apparatus R 2 , the multiplier  92  in the relay apparatus R 2  multiplies the received uplink signals with the orthogonal code “1, −1” unique to the relay apparatus R. When the uplink signals multiplied with the orthogonal code are combined using the buffer  46  and the adder  47 , the original uplink signal is regenerated. 
       FIG. 21D  depicts an example of the uplink signal outside the coverage area of the relay apparatus R 2  that relays the uplink signals of  FIG. 21C . The original uplink signals S 21  and S 22  are transmitted in the time slots  572  and  574 , respectively. The time slots  571  and  572  are assigned to mobile station apparatuses not served by the relay apparatus R 2 . 
     According to the present embodiment, it becomes possible to reduce the interference that may occur between the wireless signals transmitted/received by the plurality of relay apparatuses R 1  and R 2  when the relay apparatuses R 1  and R 2  are provided in the same wireless communication system  1 . 
     The description given above with reference to  FIGS. 18 to 21  has dealt with an embodiment implemented in a wireless communication system employing a time division multiple access scheme. It will also be noted that in a wireless communication system employing a frequency division multiple access scheme, interference between different relay apparatuses can likewise be reduced by multiplying an orthogonal code on the signals repetitively mapped to a plurality of frequency bands. Furthermore, in the case of a wireless communication system employing a time division multiple access scheme in combination with a frequency division multiple access, interference between different relay apparatuses can also be reduced by multiplying an orthogonal code on the signals repetitively mapped to a plurality of time slots and frequency bands. 
     Next, a description will be given of an alternative embodiment for reducing the interference that may occur between the wireless signals transmitted/received by the plurality of relay apparatuses R 1  and R 2 . In this embodiment, interleaved frequency division multiple access (IFDMA) modulation is performed in the respective coverage areas of the plurality of relay apparatuses R 1  and R 2  by using phase rotations unique to the respective relay apparatuses R 1  and R 2 . In the interleaved frequency division multiple access modulation, since signals are arranged in interleaved fashion between the coverage areas of the respective relay apparatuses R 1  and R 2  so as not to overlap each other along the frequency axis, interference between the plurality of relay apparatuses can be reduced. 
       FIG. 22  is a diagram illustrating a second configuration example of the relay apparatus R depicted in  FIG. 17 . Reference numeral  100  is a phase rotation information generating unit,  101  is an IFDMA modulation unit, and  102  is an IFDMA demodulation unit. The relay apparatus R thus includes the phase rotation information generating unit  100 , the IFDMA modulation unit  101 , and the IFDMA demodulation unit  102 . The same component elements as those of the relay apparatus R depicted in  FIG. 12  are designated by the same reference numerals. 
     I and Q complex components of the downlink signal are caused to occur in a plurality of time slots in a repetitive manner by using the buffer  44  and the switch  45 . For simplicity of explanation, the I and Q complex components may sometimes be referred to as the “symbols”. The phase rotation information generating unit  100  generates phase rotation amounts, θ 1 , θ 2 , θ 3 , θ 4 , . . . , with which to multiply the respective symbols s 1 , s 2 , s 3 , s 4 , . . . that occur in the plurality of time slots T 1 , T 2 , T 3 , T 4 , . . . in a repetitive manner. 
     The step width (θ 2 −θ 1 )=(θ 3 −θ 2 )=(θ 4 −θ 3 ), . . . between the respective phase rotation amounts, θ 1 , θ 2 , . . . , is uniquely determined for each relay apparatus R. In the illustrated example, the same symbol is caused to occur in four time slots in a repetitive manner by using the buffer  44  and the switch  45 . In this case, the phase rotation information generating unit  100  in the relay apparatus R 1  may generate, for example, phase rotation amounts (0, π/2, π, 3π/2) that change by a step width of (π/2) from one to another. On the other hand, the phase rotation information generating unit  100  in the relay apparatus R 2  may generate, for example, phase rotation amounts (0, π, 0, πn) that change by a step width of π from one to another. 
     The IFDMA modulation unit  101  applies IFDMA modulation to the downlink signal in the coverage area of the relay apparatus R by applying phase rotations of amounts θ 1 , θ 2 , θ 3 , θ 4 , . . . to the repetitively occurring symbols s 1 , s 2 , s 3 , s 4 , . . . . Since IFDMA modulation is applied by using the phase rotation amounts unique to the respective relay apparatuses R, the frequency spectra of the different relay apparatuses R become orthogonal to each other on the frequency axis, and interference between the relay apparatuses R is thus reduced. 
     As will be described later, each mobile station apparatus MS served by the relay apparatus causes the symbols s 1 , s 2 , s 3 , s 4 , . . . of the uplink signal to occur in the plurality of time slots in a repetitive manner. The mobile station apparatus MS applies IFDMA modulation to the uplink signal by using the phase rotation amount unique to the relay apparatus R serving the mobile station apparatus MS. 
     The IFDMA demodulation unit  102  in the relay apparatus R applies IFDMA demodulation to the uplink signal by applying phase rotations of the unique amounts θ 1 , θ 2 , θ 3 , θ 4 , . . . to the repetitively occurring symbols s 1 , s 2 , s 3 , s 4 , . . . contained in the uplink signal. The symbols s 1 , s 2 , s 3 , s 4 , . . . occurring in the plurality of time slots in a repetitive manner are combined by using the buffer  46  and the adder  47 . 
       FIG. 23  is a diagram illustrating a second configuration example of the mobile station apparatus MS depicted in  FIG. 17 . Reference numeral  103  is a phase rotation amount detection unit,  104  is an IFDMA demodulation unit, and  105  is an IFDMA modulation unit. The mobile station apparatus MS thus includes the phase rotation amount detection unit  103 , the IFDMA demodulation unit  104 , and the IFDMA modulation unit  105 . The same component elements as those of the mobile station apparatus MS depicted in  FIG. 13  are designated by the same reference numerals. In the actual configuration, an analog-digital converter is placed between the antenna duplexer  21  and the IFDMA demodulation unit  104 , and a digital-analog converter is placed between the IFDMA modulation unit  105  and the antenna duplexer  21 , but these converters are not depicted or described for simplicity of illustration. 
     When the IFDMA-modulated signal is received, the phase rotation amount detection unit  103  detects the phase rotation amounts θ 1 , θ 2 , θ 3 , θ 4 , . . . used to modulate the signal. For example, the phase rotation amount detection unit  103  may apply IFDMA demodulation to the symbols contained in the received signal by using each of a plurality of possible phase rotation amounts expected to be assigned to the relay apparatus R, and may determine that the phase rotation amount detected when a signal strength exceeding a predetermine threshold value is detected is the phase rotation amount used for the modulation. 
     The IFDMA demodulation unit  104  applies IFDMA demodulation to the downlink signal by applying the detected phase rotation amounts θ 1 , θ 2 , θ 3 , θ 4 , . . . to the repetitively occurring symbols s 1 , s 2 , s 3 , s 4 , . . . contained in the received signal. The symbols s 1 , s 2 , s 3 , s 4 , . . . occurring in the plurality of time slots in a repetitive manner are combined by using the buffer  50  and the adder  51 . 
     On the other hand, the symbols contained in the uplink signal are caused to occur in a plurality of time slots in a repetitive manner by using the buffer  53  and the switch  54 . The IFDMA modulation unit  105  applies IFDMA modulation to the uplink signal by applying the phase rotation amounts, θ 1 , θ 2 , θ 3 , θ 4 , . . . , detected by the phase rotation amount detection unit  103 , to the symbols s 1 , s 2 , s 3 , s 4 , . . . occurring in the plurality of time slots in a repetitive manner. The IFDMA-modulated uplink signal is transmitted from the antenna  20  to the relay apparatus R. 
     According to the present embodiment, it becomes possible to reduce the interference that may occur between the wireless signals transmitted/received by the plurality of relay apparatuses R 1  and R 2  when the relay apparatuses R 1  and R 2  are provided in the same wireless communication system  1 . 
     Next, one example of a scheduling method employed in the base station apparatus BS will be described.  FIG. 24  is a diagram illustrating the configuration of a third embodiment implemented in a wireless communication system  1 . The same component elements as those of the wireless communication system  1  depicted in  FIG. 1  are designated by the same reference numerals. In the present embodiment, it is assumed that the mobile station apparatuses MS 1  and MS 2  directly communicate with the base station apparatus BS, while the mobile station apparatus MS 3  is served by the relay apparatus R. 
     It is also assumed that the coverage area of the base station apparatus BS and the coverage area of the relay apparatus R are not separated from each other. For example, not only wireless signals transmitted from the base station apparatus BS but also wireless signals transmitted from the relay apparatus R are received by the mobile station apparatus MS 2 , while on the other hand, wireless signals transmitted from the relay apparatus R are received not only by the base station apparatus BS but also by the mobile station apparatus MS 2 . 
     The present embodiment is intended to reduce the interference that may occur between the coverage area of the base station apparatus BS and the coverage area of the relay apparatus R. When scheduling the wireless resources, the base station apparatus BS assigns wireless resources to wireless communications with the mobile station apparatuses MS 1  and MS 2  not served by the relay apparatus R, by excluding the plurality of wireless resources that the mobile station apparatus MS 3  uses within the coverage area of the relay apparatus R. 
       FIG. 25  is a diagram illustrating a configuration example of the relay apparatus R depicted in  FIG. 24 . Reference numeral  110  designates an identification information appending unit. The relay apparatus R thus includes the identification information appending unit  110 . The same component elements as those of the relay apparatus R depicted in  FIG. 12  are designated by the same reference numerals. The identification information appending unit  110  appends, to the downlink signal to be transmitted from the antenna  17 , information identifying that the downlink signal has been relayed by the relay apparatus R. The information appended to the wireless signal to identify that the signal has been relayed by the relay apparatus R will be referred to as the “identification information.” 
       FIG. 26  is a diagram illustrating a configuration example of the mobile station apparatus MS depicted in  FIG. 24 . Reference numeral  111  is a relay identifying unit, and  112  is a relay notification signal generating unit. The mobile station apparatus MS thus includes the relay identifying unit  111  and the relay notification signal generating unit  112 . The same component elements as those of the mobile station apparatus MS depicted in  FIG. 13  are designated by the same reference numerals. In the actual configuration, an analog-digital converter is placed between the antenna duplexer  21  and the buffer  50 , and a digital-analog converter is placed between the switch  54  and the antenna duplexer  21 , but these converters are not depicted or described for simplicity of illustration. 
     The relay identifying unit  111  detects identification information from the received downlink signal and identifies whether the received signal is one that has been relayed by the relay apparatus R. The relay identifying unit  111  outputs an identification result signal indicating the result of the identification. The relay notification signal generating unit  112 , in accordance with the identification result signal, generates a relay notification signal indicating that the mobile station apparatus MS is currently served by the relay apparatus R. The transmission processing unit  28  transmits the relay notification signal to the base station apparatus BS. 
       FIG. 27  is a diagram illustrating a first configuration example of the base station apparatus BS depicted in  FIG. 24 . Reference numeral  36  designates a relay notification signal detection unit. The base station apparatus BS thus includes the relay notification signal detection unit  36 . The same component elements as those of the base station apparatus BS depicted in  FIG. 10  are designated by the same reference numerals. The relay notification signal detection unit  36  detects the relay notification signal from the signal received from the mobile station apparatus MS. 
     For each of the mobile station apparatuses MS currently connected to the base station apparatus BS, the terminal information storage unit  34  stores, based on the detection result of the relay notification signal, information indicating whether the mobile station apparatus MS is currently served by the relay apparatus R. The scheduler  33  schedules the wireless resources so that the wireless resources assigned for wireless communications with the mobile station apparatuses MS 1  and MS 2  not served by the relay apparatus R do not overlap the plurality of wireless resources that the mobile station apparatus MS 3  uses within the coverage area of the relay apparatus R. 
       FIGS. 28A to 28C  are explanatory diagrams illustrating a fourth example of the downlink signal for which the wireless resources have been assigned by the base station apparatus BS.  FIG. 28A  depicts the downlink signals transmitted from the base station apparatus BS. Reference numerals  581  to  588  indicate eight successive time slots. The time slots  581  and  585  are assigned to the downlink signals S 1  and S 2  destined for the mobile station apparatus MS 3  served by the relay apparatus R. On the other hand, the time slots  583 ,  584 ,  587 , and  588  are assigned to the mobile station apparatuses not served by the relay apparatus R. 
       FIG. 28B  depicts an example of the downlink signal within the coverage area of the relay apparatus R. The downlink signal S 1  is mapped to the time slot  581  and its immediately succeeding time slot  582  in a repetitive manner. The downlink signal S 2  is mapped to the time slot  585  and its immediately succeeding time slot  586  in a repetitive manner. 
     As can be seen form  FIGS. 28A and 28B , the time slots  581 ,  582 ,  585 , and  586 , to which the downlink signals within the coverage area of the relay apparatus R are mapped, are not assigned to the mobile station apparatuses not served by the relay apparatus R.  FIG. 28C  depicts an example of the downlink signal arriving at the mobile station apparatus MS 2 . As depicted in  FIG. 28C , the signals of  FIG. 28A  and  FIG. 28B  arrive in a mixed fashion at the mobile station apparatus MS 2 . However, since the time slots  581 ,  582 ,  585 , and  586  that the signals within the coverage area of the relay apparatus R use are different from the time slots  583 ,  584 ,  587 , and  588  assigned to the signals arriving directly from the base station apparatus BS, interference between these signals is reduced. 
       FIGS. 29A to 29C  are explanatory diagrams illustrating a fourth example of the uplink signal for which the wireless resources have been assigned by the base station apparatus BS.  FIG. 29A  depicts an example of the uplink signal within the coverage area of the relay apparatus R. Reference numerals  591  to  598  indicate eight successive time slots. The uplink signal S 1  is mapped to the time slot  591  and its immediately succeeding time slot  592  in a repetitive manner. The uplink signal S 2  is mapped to the time slot  596  and its immediately succeeding time slot  597  in a repetitive manner. 
       FIG. 29B  depicts the uplink signals transmitted from the relay apparatus R. The uplink signal S 1  obtained by combining the signals received in the time slots  591  and  592  is transmitted in the time slot  592 . The uplink signal S 2  obtained by combining the signals received in the time slots  596  and  597  is transmitted in the time slot  597 . 
       FIG. 29C  depicts the uplink signals received at the base station apparatus BS. The uplink signals within the coverage area of the relay apparatus R ( FIG. 29A ) and the uplink signals transmitted from the mobile station apparatuses not served by the relay apparatus R arrive in a mixed fashion at the base station apparatus BS. Time slots  591 ,  594 ,  595 , and  598  are assigned to the mobile station apparatuses not served by the relay apparatus R. 
     However, the time slots  592 ,  593 ,  596 , and  597  that the signals within the coverage area of the relay apparatus R use are different from the time slots  591 ,  594 ,  595 , and  598  assigned to the signals arriving directly at the base station apparatus BS from the mobile station apparatuses not served by the relay apparatus R. This serves to reduce the interference between the signals within the coverage area of the relay apparatus R and the signals arriving directly at the base station apparatus BS from the mobile station apparatuses not served by the relay apparatus R. 
     According to the present embodiment, it is possible to reduce the interference that may occur between the coverage area of the base station apparatus BS and the coverage area of the relay apparatus R when the coverage area of the base station apparatus BS and the coverage area of the relay apparatus R are not separated from each other. 
     Next, an embodiment of the identification information appending unit  110  depicted in  FIG. 25  will be described. The identification information appending unit  110  may append the identification information to the relay signal, for example, by superimposing a prescribed pattern on the relay signal. For example, the identification information appending unit  110  may superimpose the prescribed pattern in a frequency band where little effect is caused on the main signal of the relay signal. Further, the identification information appending unit  110  may superimpose the prescribed pattern, for example, by code spreading. In this case, the relay identifying unit  111  depicted in  FIG. 26  detects the identification information by detecting the prescribed pattern appended to the received signal. 
     Alternatively, the identification information appending unit  110  may append the identification information to the relay signal, for example, by inverting the sign of the frequency of the relay signal, i.e., by inverting the spectrum of the received signal.  FIG. 30  is a diagram illustrating a configuration example of the identification information appending unit  110 . Reference numeral  41  is the high-power amplifier depicted in  FIG. 25 ,  120  and  123  are local oscillators,  121  and  124  are multipliers, and  122  and  125  are band-pass filters. 
     The carrier frequency of the relay signal received by the relay apparatus R is designated “fc”. The identification information appending unit  110  may include a frequency converter for converting the relay signal into a signal containing a frequency component “−fc” which is equal in amplitude but opposite in sign to the carrier frequency fc of the relay signal, and a band-limiting filter for extracting the frequency component fc from the output signal of the frequency converter. In the configuration example of the identification information appending unit  110  depicted in  FIG. 30 , a first mixer formed by the local oscillator  120  and multiplier  121  and a second mixer formed by the local oscillator  123  and multiplier  124  constitute the frequency converter. The configuration illustrated in  FIG. 30  is only one example of the configuration of the frequency converter, and is not intended to limit the implementation of the identification information appending unit  110  to the mode described hereinafter. Various configurations are possible for the implementation of the frequency converter. 
     The frequency of the intermediate frequency signal to be amplified by the high-power amplifier  41  is designated “fi”. The local oscillator  120  produces a local oscillation signal of frequency “fc+fi”. The multiplier  121  converts the relay signal into a signal containing frequency components “−fi” and “2fc+fi” by multiplying the received signal of frequency fc with the local oscillation signal output from the local oscillator  120 . 
     The band-pass filter  122  is tuned to pass the intermediate frequency “fi”, so that the band-pass filter  122  extracts the intermediate frequency signal of frequency “−fi” from the output signal of the multiplier  121 . The high-power amplifier  41  amplifies the intermediate frequency signal, which is supplied to the multiplier  124 . 
     The local oscillator  123  produces a local oscillation signal of frequency “fc−fi”. The multiplier  124  converts the intermediate frequency signal into a signal containing frequency components “−fc” and “fc−2fi” by multiplying the intermediate frequency signal of frequency “−fi” with the local oscillation signal output from the local oscillator  123 . 
     The band-pass filter  125  is tuned to pass the carrier frequency “fc”, so that the band-pass filter  125  extracts the carrier signal of frequency “−fc” from the output signal of the multiplier  124 . In this way, the identification information appending unit  110  inverts the sign of the frequency of the received signal. 
       FIG. 31  is a diagram illustrating a first configuration example of the relay identifying unit  111 . The relay identifying unit  111  identifies whether the received signal is one that has been relayed by the relay apparatus R, by checking whether the sign of the frequency of the received signal has been inverted by the identification information appending unit  110  depicted in  FIG. 30 . Reference numeral  130  is a quadrature detection unit,  131  and  132  are pattern detection units,  133  is a sign identifying unit, and  134  is a rotation direction correction unit. The relay identifying unit  111  thus includes the quadrature detection unit  130 , the pattern detection units  131  and  132 , the sign identifying unit  133 , and the rotation direction correction unit  134 . 
     The quadrature detection unit  130  applies quadrature detection to the received signal to produce an in-phase component signal (I-component signal) and a quadrature component signal (Q-component signal). The pattern detection unit  131  calculates correlation between the prescribed pattern known to be contained in the received signal and the symbol pattern at a signal point corresponding to the in-phase and quadrature component signals output from the quadrature detection unit  130 . The pattern detection unit  131  may use, for example, a pilot signal or a reference signal as the known pattern. 
     On the other hand, the pattern detection unit  132  calculates correlation between the prescribed pattern and the symbol pattern corresponding to the signals obtained by reversing the phase rotation directions of the in-phase and quadrature component signals output from the quadrature detection unit  130 . 
     Based on the correlations calculated by the pattern detection units  131  and  132 , the sign identifying unit  133  identifies whether the sign of the carrier frequency of the signal received by the wireless communication apparatus X has been inverted or not, that is, whether the received signal is one that has been relayed by the relay apparatus. 
     If the correlation calculated by the pattern detection unit  131  is higher than the correlation calculated by the pattern detection unit  132 , the sign identifying unit  133  identifies that the sign of the carrier frequency of the received signal has not been inverted. If the correlation calculated by the pattern detection unit  131  is lower than the correlation calculated by the pattern detection unit  132 , the sign identifying unit  133  identifies that the sign of the carrier frequency of the received signal has been inverted. The sign identifying unit  133  outputs an identification result signal indicating whether the received signal is one that has been relayed by the relay apparatus. 
     In accordance with the identification result from the sign identifying unit  133 , the rotation direction correction unit  134  corrects the phase rotation directions of the in-phase and quadrature component signals output from the quadrature detection unit  130 . If the sign of the carrier frequency of the received signal has not been inverted, the rotation direction correction unit  134  passes the in-phase and quadrature component signals output from the quadrature detection unit  130  directly to the reception processing unit  26  that follows. 
     If the sign of the carrier frequency of the received signal has been inverted, the rotation direction correction unit  134  reverses the phase rotation directions of the in-phase and quadrature component signals output from the quadrature detection unit  130 , and supplies the thus corrected signals to the reception processing unit  26  that follows. The rotation direction correction unit  134  may reverse the phase rotation directions of the in-phase and quadrature component signals, for example, by interchanging the in-phase and quadrature components of the in-phase and quadrature component signals input to it. Alternatively, the rotation direction correction unit  134  may reverse the phase rotation directions of the in-phase and quadrature component signals, for example, by inverting one or the other of the values of the in-phase and quadrature component signals input to it. 
     According to the present embodiment, the information identifying whether the signal is one that has been relayed by the relay apparatus can be appended to the relay signal by inverting or not inverting the sign of the carrier frequency of the relay signal. The wireless resource of the wireless signal is not consumed if the sign of the carrier frequency is inverted. 
     In the configuration examples described with reference to  FIGS. 25 to 27 , the identification information appending unit  110  in the relay apparatus R has been described as appending the identification information to the downlink signal. Alternatively, the identification information appending unit  110  in the relay apparatus R may append the identification information to the uplink signal. The base station apparatus BS may identify whether or not the mobile station apparatus MS is currently served by the relay apparatus R, by checking whether identification information is appended to the uplink signal received from the mobile station apparatus MS. 
       FIG. 32  is a diagram illustrating a second configuration example of the base station apparatus BS depicted in  FIG. 24 . Reference numeral  37  designates a relay identifying unit. The base station apparatus BS thus includes the relay identifying unit  37 . The same component elements as those of the base station apparatus BS depicted in  FIG. 10  are designated by the same reference numerals. The relay identifying unit  37  detects identification information from the uplink signal received from the mobile station apparatus MS and identifies whether or not the mobile station apparatus MS is currently served by the relay apparatus R. The relay identifying unit  37  may be identical in configuration to the earlier described relay identifying unit  111 . 
     The identification result from the relay identifying unit  37  is stored in the terminal information storage unit  34 . The scheduler  33  schedules the wireless resources so that the wireless resources assigned for wireless communications with the mobile station apparatuses MS 1  and MS 2  not served by the relay apparatus R do not overlap the plurality of wireless resources that the mobile station apparatus MS 3  uses within the coverage area of the relay apparatus R. 
     According to the present embodiment, by appending the identification information to the uplink signal, it is possible to identify at the base station apparatus BS whether or not the mobile station apparatus MS is currently served by the relay apparatus R. Based on the identification result, the base station apparatus BS can assign the wireless resources to the mobile station apparatus MS in such a manner as to reduce the interference that may occur between the coverage area of the base station apparatus BS and the coverage area of the relay apparatus R. 
     The description given above with reference to  FIGS. 24 to 32  has dealt with an embodiment implemented in a wireless communication system employing a time division multiple access scheme. It will also be noted that in a wireless communication system employing a frequency division multiple access scheme, wireless resources other than the plurality of wireless resources used within the coverage area of the relay apparatus can be assigned in like manner to wireless communications with the mobile station apparatuses not served by the relay apparatus. 
     Next, a description will be given of an alternative embodiment for identifying, at the mobile station apparatus having the configuration of  FIG. 26 , whether or not the received signal is one that has been relayed by the relay apparatus R.  FIG. 33  is a diagram illustrating a second configuration example of the relay identifying unit  111 . The relay identifying unit  111  calculates correlation between the signals transmitted using a plurality of wireless resources. The relay identifying unit  111  may be configured to calculate correlation between the signals transmitted using a plurality of time slots or to detect correlation between the signals transmitted using a plurality of frequency bands. 
     When the relay apparatus R is repetitively transmitting identical signals on a plurality of wireless resources within the coverage area of the relay apparatus R, if correlation between the repetitively transmitted signals is calculated, the correlation will yield a large value. The relay identifying unit  111  may calculate, for example, correlation between the pilot signals repetitively transmitted on a plurality of wireless resources. If the calculated correlation is not smaller than a predetermined threshold value, it is determined that the received signal is one that has been relayed by the relay apparatus R. If the calculated correlation is smaller than the predetermined threshold value, it is determined that the received signal has arrived directly from the base station apparatus BS. 
     Reference numeral  140  is a buffer,  141  is a correlation detection unit, and  142  is a comparison unit. The relay identifying unit  111  thus includes the buffer  140 , the correlation detection unit  141 , and the comparison unit  142 . 
     The buffer  140  stores a pilot signal received in a given time slot. The correlation detection unit  141  calculates correlation between the pilot signal received in some other time slot and the pilot signal stored in the buffer  140 . The comparison unit  142  compares the calculated correlation value with the predetermined threshold value, to identify whether or not the received signal is one that has been relayed by the relay apparatus R. 
     The configuration depicted in  FIG. 33  represents an embodiment for use in a communication system employing a time division multiple access scheme. In a communication system employing a frequency division multiple access scheme, the correlation detection unit  141  may detect correlation between the pilot signals transmitted in different frequency bands. 
     In this embodiment also, the mobile station apparatus MS can identify whether the received signal is one that has been relayed by the relay apparatus. 
     Next, a description will be given of the operation of the base station apparatus BS when the mobile station apparatus MS moves from the coverage area of the base station apparatus BS to the coverage area of the relay apparatus R or from the coverage area of the relay apparatus R to the coverage area of the base station apparatus BS. 
       FIG. 34  is a diagram illustrating the configuration of a fourth embodiment implemented in a wireless communication system. The same component elements as those of the wireless communication system  1  depicted in  FIG. 1  are designated by the same reference numerals. The configuration of the base station apparatus BS may be the same as that depicted in  FIG. 27  or  32 . Suppose here that the mobile station apparatus MS 1  moves from the coverage area of the base station apparatus BS to the coverage area of the relay apparatus R or from the coverage area of the relay apparatus R to the coverage area of the base station apparatus BS. 
       FIG. 35  is an explanatory diagram illustrating the scheduling process performed at the base station apparatus BS depicted in  FIG. 34 . In an alternative embodiment, the following operations CA to CF may be implemented as steps. 
     In operation CA, the relay notification signal detection unit  36  or relay identifying unit  37  in the base station apparatus BS determines whether or not the mobile station apparatus MS 1  is currently served by the relay apparatus R. The determination as to whether or not the mobile station apparatus MS 1  is currently served by the relay apparatus R may be made in the same manner as described above with reference to  FIGS. 24 to 33 . If the mobile station apparatus MS 1  is currently served by the relay apparatus R (Y in operation CA), the process proceeds to operation CB. If the mobile station apparatus MS 1  is not served by the relay apparatus R (N in operation CA), the process proceeds to operation CE. 
     In operation CB, the scheduler  33  determines the wireless resources to be used for wireless communication between the base station apparatus BS and the mobile station apparatus MS 1 . In operation CC, the scheduler  33  determines the plurality of wireless resources to which the relay signal to be transmitted to or received from the mobile station apparatus MS 1  is to be mapped in a repetitive manner within the coverage area of the relay apparatus R. 
     In operation CD, the wireless communication unit  32  transmits the scheduling information specifying the wireless resources determined in operation CB and the wireless resource information specifying the wireless resources determined in operation CC to the mobile station apparatus MS 1  and the relay apparatus R. Here, if the relationship between the wireless resources determined in operation CB and the wireless resources determined in operation CC is predetermined, the scheduling information concerning the wireless resources determined in operation CB need not necessarily be transmitted. After operation CD, the process is terminated. 
     In operation CE, the scheduler  33  determines the wireless resources to be used for wireless communication between the base station apparatus BS and the mobile station apparatus MS 1 . For example, the scheduler  33  may assign to the mobile station apparatus MS 1  the wireless resources that are different from the wireless resources that other mobile station apparatus served by the relay apparatus R use within the coverage area of the relay apparatus R. 
     In operation CF, the wireless communication unit  32  transmits the scheduling information specifying the wireless resources determined in operation CE to the mobile station apparatus MS 1 . 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment(s) of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.