Transmission method and reception method

Abstract

In a multi-antenna communication system using LDPC codes, a simple method is used to effectively improve the received quality by performing a retransmittal of less data without restricting applicable LDPC codes. In a case of a non-retransmittal, a multi-antenna transmitting apparatus (100) transmits, from two antennas (114A,114B), LDPC encoded data formed by LDPC encoding blocks (102A,102B). In a case of a retransmittal, the multi-antenna transmitting apparatus (100) uses a transmission method, in which the diversity gain is higher than in the previous transmission, to transmit only a part of the LDPC encoded data as previously transmitted. For example, the only the part of the LDPC encoded data to be re-transmitted is transmitted from the single antenna (114A).

1 . A transmission apparatus comprising:
 an encoding circuit configured to encode data according to a parity check matrix of Low Density Parity Check coding to generate an encoded data sequence such that the encoded data sequence includes a first bit and a second bit, the parity check matrix having a first column and a second column to generate the first bit and the second bit, respectively; and   a transmitting circuit configured to transmit an orthogonal frequency divisional multiplexing (OFDM) signal including the encoded data sequence and configured to retransmit an OFDM signal including the first bit without retransmitting the second bit, wherein   a first number of 1 bits in the first column is greater than a second number of 1 bits in the second column.   
     
     
         2 . A reception apparatus comprising:
 a receiving circuit configured to receive:
 an orthogonal frequency divisional multiplexing (OFDM) signal including an encoded data sequence; and 
 an OFDM singal including a first retransmitted bit which is identical to a first bit included in the encoded data sequence, a second bit in the encoded data sequence having not been retransmitted; and 
   a decoding circuit configured to decode the encoded data sequence according to a parity check matrix of Low Density Parity Check coding to generate decoded data, the parity check matrix having a first column and a second column to generate the first bit and the second bit, respectively, wherein   a first number of 1 bits in the first column is greater than a second number of 1 bits in the second column.