On relay selection in frequency selective channels

We consider relay selection in cooperative relay networks with frequency selective fading, and focus on a system where multiple decode-and-forward relays share a single channel orthogonal to the source. We propose a relay selection scheme and end-to-end transceiver architecture which employs a simple decision feedback equalizer, and we show analytically that the proposed system can optimally exploit both spatial diversity and frequency diversity. By simulation, we compare the BER performance of a finite-length MMSE-DFE receiver with that of the MLSE and linear ZF receivers. The numerical results show that the finite-length MMSE-DFE receiver, combined with the relay selection method and zero-padded transmission, can achieve full diversity.