Distributed space-time decoding with Two-Pilot channel estimation for wireless relay networks

In this paper, a novel channel estimation scheme called Two-Pilot Estimation (TPE) is proposed for distributed space-time decoding in Amplify-and-Forward (AF) based wireless relay networks. For Maximum Likelihood (ML) decoding at the destination, directly estimating the product of source-relay (S-R) channel and relay-destination (R-D) channel either is difficult, or causes drastic receiver degradation. The TPE scheme employs two pilot space-time codes to jointly estimate the channels. One pilot code is used to experience the source-relay-destination (S-R-D) channels, and another one is assigned for the R-D channel. To reduce computation complexity, Two-Step TPE and LSE-TPE estimators are proposed as the suboptimal TPE estimators. Optimal power allocation between two pilots is also derived. Simulation shows that the TPE scheme is better than the product based estimation schemes.