A decode and forward cooperation scheme with soft relaying in wireless communication

This paper proposes a new decode and forward scheme with soft information relaying technique to overcome the performance degradation happening when the quality of the inter-user channel is very bad. Based on the scheme, soft log-likelihood ratio of the relay decoder is quantized, encoded, superimposedly modulated and then forwarded to the destination. The destination receiver employs an iterative superposition decoder and modified maximum a posteriori probability decoder to recover the transmitted signal from the source. The performance of the scheme is evaluated by simulation. We show that the new scheme can significantly outperform the conventional decode and forward scheme even in a very poor inter-user channel.