Iterative Channel Estimation and Data Detection for Amplify-and-Forward Relay Networks

We consider channel estimation in amplify-and-forward wireless relay networks when non-orthogonal coherent distributed space-time coding is done at relays. We propose to perform iterative channel estimation and data detection based on parallel interference cancelation (PIC) at the receiver. The schemes that we propose are based on soft or hard estimates of the transmitted data symbols. We illustrate the performance improvement compared to the classical approach of pilot-only-based channel estimation and minimum mean-square-error detection. Also, we show that semi-blind channel estimation together with PIC detection is particularly promising for large signal constellations. Moreover, we show that the use of hard estimates of symbols in the proposed iterative receiver provides satisfying results, while requiring a lower computational complexity.