Abstract:
In this paper, we investigate joint design of quasi-cyclic low-density-parity-check (QC-LDPC)
codes for coded cooperation system with joint iterative decoding in the
destination. First, QC-LDPC codes based on the base matrix and exponent matrix
are introduced, and then we describe two types of girth-4 cycles in QC-LDPC codes
employed by the source and relay. In the equivalent parity-check matrix corresponding
to the jointly designed QC-LDPC codes employed by the source and relay, all girth-4
cycles including both type I and type II are cancelled. Theoretical analysis and
numerical simulations show that the jointly designed QC-LDPC coded cooperation well
combines cooperation gain and channel coding gain, and outperforms the coded noncooperation
under the same conditions. Furthermore, the bit error rate performance of the
coded cooperation employing jointly designed QC-LDPC codes is better than those of
random LDPC codes and separately designed QC-LDPC codes over AWGN channels.
