Error-prone relay networks with soft- and hard-decision re-encoding

In this paper, we investigate the performance of cooperative coding in a three-node error-prone relay network. It is widely believed that soft re-encoding at the relay will be beneficial for the overall bit error rate after turbo-decoding at the destination. In particular, soft re-encoding is supposed to combine the advantages of decode-and-forward and estimate-and-forward. However, we show that the information loss due to soft re-encoding and the forwarding of analog instead of discrete values might outbalance its benefits. We exemplarily unveil scenarios for which hard re-encoding performs best, soft re-encoding is superior or both have the same performance.