Low-complexity turbo decoding scheme for two-way relay network

A low-complexity two-user turbo decoding scheme for two-way relay network is proposed. In the relay, the superimposed packets have to be decoded to the arithmetic summation of two source packets based on the sum trellis. In the sum trellis, there are some symmetrical states, especially when the sources use identical component codes. These symmetrical states provide same information to the turbo decoder. This observation motives a reconstruction of the sum trellis by merging the symmetrical sates in the trellis. By this mergence, a simplified sum trellis with the less state number is given. Complexity analysis shows that the computational complexity of two-user turbo decoding with simplified sum trellis is reduced to half, compared with one with sum trellis.