OFDM-CDMA equipment and method

Abstract

An OFDM signal transmission apparatus is provided, which includes a mapping unit configured to map first signals into N subcarriers and second signals into M subcarrier(s) to form an OFDM signal, wherein N is larger than M. The first signals are each indicating a same bit of retransmission information and the second signals are each indicating a same bit of information other than retransmission information. The OFDM signal transmission apparatus further includes a transmitting unit configured to transmit the formed OFDM signal.

The invention claimed is: 
     
       1. A signal reception apparatus, comprising:
 receiving circuitry, which, in operation, receives signals generated by identical bit information, the received signals being mapped onto at least two subcarriers in a symbol; 
 Fast Fourier Transform (FFT) circuitry, which in operation, performs FFT processing on the received signals; and 
 signal extraction circuitry, which, in operation, extracts the identical bit information from the FFT processed signals; 
 wherein the at least two subcarriers include a DC subcarrier and one of the received signals generated by the identical bit information is mapped onto the DC subcarrier. 
 
     
     
       2. The signal reception apparatus according to  claim 1 , wherein the identical bit information corresponds to important information. 
     
     
       3. A signal reception method comprising:
 receiving signals generated by identical bit information, the received signals being mapped onto at least two subcarriers in a symbol; 
 performing Fast Fourier Transform (FFT) processing on the received signals; and 
 extracting the identical bit information from the FFT processed signals; 
 wherein the at least two subcarriers include a DC subcarrier and one of the received signals generated by the identical bit information is mapped onto the DC subcarrier. 
 
     
     
       4. The signal reception method according to  claim 3 , wherein the identical bit information corresponds to important information. 
     
     
       5. The signal reception method of  claim 3  wherein the identical bit information corresponds to control information. 
     
     
       6. The signal reception method of  claim 5 , comprising using the extracted bit information to control retransmissions. 
     
     
       7. The signal reception apparatus of  claim 1  wherein the identical bit information corresponds to control information. 
     
     
       8. The signal reception apparatus of  claim 1 , comprising control circuitry, which, in operation, uses the extracted bit information to control retransmissions. 
     
     
       9. A communication apparatus, comprising:
 a receiver, which, in operation:
 receives signals generated by identical bit information, the received signals being mapped onto at least two subcarriers in a symbol; 
 performs Fast Fourier Transform (FFT) processing on the received signals; and 
 extracts bit information from the FFT processed signals, wherein the at least two subcarriers include a DC subcarrier and one of the received signals generated by the identical bit information is mapped onto the DC subcarrier; and 
 
 a transmitter, which, in operation, transmits signals. 
 
     
     
       10. The communication apparatus according to  claim 9 , wherein the identical bit information corresponds to important information. 
     
     
       11. The communication apparatus of  claim 9  wherein the identical bit information corresponds to control information. 
     
     
       12. The communication apparatus of  claim 9 , comprising control circuitry, which, in operation, uses the extracted bit information to control at least one of the receiver and the transmitter.