Cooperative MIMO Relaying with Distributed Space-Time Block Codes

In this paper, space-time block codes (STBCs), which gain from spatial transmit diversity, are applied in a distributed fashion at several cooperating relay stations (RSs) with multiple transmit antennas. It is well known that non-distributed STBCs exhibit a degraded bit error rate (BER) performance in spatially correlated MIMO channels. Applying distributed STBCs in cooperative relay networks reduces the probability of correlated channel coefficients as the RSs are spatially separated. In this paper, the Chernoff bound of the BER in Rayleigh fading channels is extended to the case of correlated channel coefficients at the same relay station and different receive powers from different cooperating RSs. It is shown that the BER performance has a higher sensitivity to spatial correlation in MIMO channels than to different receive powers at the receiver from several cooperating RSs for distributed space-time coding. The theoretical results are confirmed by means of simulations