Precoding for Distributed Space-Time Codes in Cooperative Diversity-Based Downlink

In this paper, we investigate the cooperative diversity concept for use in MIMO multi-cell networks. We show that, in such networks, cooperative diversity processing must be optimized to account for the variability of channel conditions across the cooperative devices. This can be done via distributed precoding and, in mobile networks, it is based realistically on channel statistics. The cooperative MIMO correlation matrix admits a special structure which is used to optimize the precoder. We investigate algorithms for exact error-rate and low-complexity approximated optimization. Gains are evaluated in multi-cell scenarios with collaborating base stations.