MMSE-Based Non-Regenerative Parallel MIMO Relaying with Simplified Receiver

This paper considers a cooperative MIMO relaying system in which the source sends information to the destination with the aid of multiple relays, each equipped with multiple antennas. We design optimal linear relaying matrices that minimize the mean square error between the source and the received signal vectors under a total transmitted power constraint imposed on all the relays. The optimal matrices are obtained by solving the corresponding Karush-Kuhn-Tucker (KKT) conditions. Simulation results show significant advantages of the newly designed relaying matrices over other competing approaches in terms of bit-error rate (BER) performance. Moreover, this strategy enables the self-demultiplexing of the spatial substreams without the need for a MIMO combiner at the destination, so that a simplified receiver structure can be used without performance loss. In addition, the new design can serve as a suboptimal solution for multiuser MIMO relaying applications.