Transmission method, transmission control method, and communication apparatus

Abstract

A transmission method is provided for a communication system in which communications using a plurality of communication methods having different transmission parameters are performed at the same frequency (in frequency bands that at least partially overlap with each other). The transmission method includes: generating a first symbol group that includes a control symbol for causing a communication partner apparatus to recognize that communication using a first communication method is to be performed and a second symbol group that includes a data symbol for the first communication method; transmitting the first symbol group at a first transmit power; and transmitting the second symbol group at a second transmit power that is smaller than the first transmit power.

What is claimed is: 
     
         1 . A reception method for a reception apparatus comprising:
 receiving a first symbol group and a second symbol group from a base station, wherein the first symbol group is transmitted at a first transmit power and includes a first gain control (AGC) symbol and a control symbol for causing the reception apparatus to recognize that a short-range communication is to be performed, and wherein the second symbol group is transmitted at a second transmit power that is smaller than the first transmit power and includes a second AGC symbol and a data symbol for the short-range communication;   adjusting a first received-signal level of the first symbol group using the first AGC symbol and recognizing that the short-range communication is to be performed; and   adjusting a second received-signal level of the second symbol group using the second AGC symbol.   
     
     
         2 . The reception method according to  claim 1 , wherein the first symbol group includes another control symbol indicating which of a first communication method for short-range communication and a second communication method for long-range communication is to be performed. 
     
     
         3 . The reception method according to  claim 1 , wherein a relationship given by expression (1) is satisfied between a first average electric power of signal points in an in-phase/quadrature-phase plane for each symbol of the first symbol group and a second average electric power of signal points in the in-phase/quadrature-phase plane for each symbol in the second symbol group, 
       
         
           
             
               
                 
                   
                     
                       
                         1 
                         M 
                       
                        
                       
                         
                           ∑ 
                           
                             j 
                             = 
                             1 
                           
                           M 
                         
                          
                         
                           ( 
                           
                             
                               I 
                               
                                 a 
                                 , 
                                 j 
                               
                               2 
                             
                             + 
                             
                               Q 
                               
                                 a 
                                 , 
                                 j 
                               
                               2 
                             
                           
                           ) 
                         
                       
                     
                     > 
                     
                       
                         1 
                         N 
                       
                        
                       
                         
                           ∑ 
                           
                             j 
                             = 
                             1 
                           
                           N 
                         
                          
                         
                           ( 
                           
                             
                               I 
                               
                                 b 
                                 , 
                                 j 
                               
                               2 
                             
                             + 
                             
                               Q 
                               
                                 b 
                                 , 
                                 j 
                               
                               2 
                             
                           
                           ) 
                         
                       
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
         where M denotes a number of signal points in the in-phase/quadrature-phase plane for the first symbol group, N denotes a number of signal points in the in-phase/quadrature-phase plane for the second symbol group, Ia,j denotes an in-phase component of each signal point in the first symbol group, Qa,j denotes a quadrature component of each signal point in the first symbol group, Ib,j denotes an in-phase component of each signal point in the second symbol group, and Qb,j denotes a quadrature component of each signal point in the second symbol group. 
       
     
     
         4 . The reception method according to  claim 1 ,
 wherein a plurality of time segments in which a certain number of the first symbol groups are transmittable are provided between adjacent time segments in which the second symbol group is transmitted; and   communication apparatuses that support a first communication method for the short-range communication respectively transmit the first symbol groups in mutually different time segments within the plurality of time segments.   
     
     
         5 . The reception method according to  claim 1 ,
 wherein a single time segment in which the first symbol group is transmittable is provided between adjacent time segments in which the second symbol group is transmitted, and   in the single time segment, the first symbol group is transmitted from one of a plurality of communication apparatuses that support a first communication method for short-range communication.   
     
     
         6 . The reception method according to  claim 1 ,
 wherein the communication using a first communication method for short-range communication is performed between the reception apparatus and the base station.   
     
     
         7 . A reception apparatus comprising:
 reception circuitry which, in operation, receives a first symbol group and a second symbol group from a base station, wherein the first symbol group is transmitted at a first transmit power and includes a first gain control (AGC) symbol and a control symbol for causing the reception apparatus to recognize that a short-range communication is to be performed, and wherein the second symbol group is transmitted at a second transmit power that is smaller than the first transmit power and includes a second AGC symbol and a data symbol for the short-range communication; and   control circuitry, which in operation, adjusts a first received-signal level of the first symbol group using the first AGC symbol and recognizing that the short-range communication is to be performed, and adjusts a second received-signal level of the second symbol group using the second AGC symbol.   
     
     
         8 . The reception apparatus according to  claim 7 , wherein the first symbol group includes another control symbol indicating which of a first communication method for short-range communication and a second communication method for long-range communication is to be performed. 
     
     
         9 . The reception apparatus according to  claim 7 , wherein a relationship given by expression (1) is satisfied between a first average electric power of signal points in an in-phase/quadrature-phase plane for each symbol of the first symbol group and a second average electric power of signal points in the in-phase/quadrature-phase plane for each symbol in the second symbol group, 
       
         
           
             
               
                 
                   
                     
                       
                         1 
                         M 
                       
                        
                       
                         
                           ∑ 
                           
                             j 
                             = 
                             1 
                           
                           M 
                         
                          
                         
                           ( 
                           
                             
                               I 
                               
                                 a 
                                 , 
                                 j 
                               
                               2 
                             
                             + 
                             
                               Q 
                               
                                 a 
                                 , 
                                 j 
                               
                               2 
                             
                           
                           ) 
                         
                       
                     
                     > 
                     
                       
                         1 
                         N 
                       
                        
                       
                         
                           ∑ 
                           
                             j 
                             = 
                             1 
                           
                           N 
                         
                          
                         
                           ( 
                           
                             
                               I 
                               
                                 b 
                                 , 
                                 j 
                               
                               2 
                             
                             + 
                             
                               Q 
                               
                                 b 
                                 , 
                                 j 
                               
                               2 
                             
                           
                           ) 
                         
                       
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
         where M denotes a number of signal points in the in-phase/quadrature-phase plane for the first symbol group, N denotes a number of signal points in the in-phase/quadrature-phase plane for the second symbol group, Ia,j denotes an in-phase component of each signal point in the first symbol group, Qa,j denotes a quadrature component of each signal point in the first symbol group, Ib,j denotes an in-phase component of each signal point in the second symbol group, and Qb,j denotes a quadrature component of each signal point in the second symbol group. 
       
     
     
         10 . The reception apparatus according to  claim 7 ,
 wherein a plurality of time segments in which a certain number of the first symbol groups are transmittable are provided between adjacent time segments in which the second symbol group is transmitted; and   communication apparatuses that support a first communication method for the short-range communication respectively transmit the first symbol groups in mutually different time segments within the plurality of time segments.   
     
     
         11 . The reception apparatus according to  claim 7 ,
 wherein a single time segment in which the first symbol group is transmittable is provided between adjacent time segments in which the second symbol group is transmitted, and   in the single time segment, the first symbol group is transmitted from one of a plurality of communication apparatuses that support a first communication method for short-range communication.   
     
     
         12 . The reception apparatus according to  claim 7 ,
 wherein the communication using a first communication method for short-range communication is performed between the reception apparatus and the base station.