Spectral Efficient Cooperative Communications via Spatial Signal Separation

We propose a communication system that utilizes two relays and multiple receiving antennas, in order to spatially separate the signals arriving concurrently at the destination and thus avoid the need for orthogonal transmissions in either the frequency or the time domain. The whole concept is based upon two key elements: a) To combat the half-duplex constraint by having two relays transmitting alternatively, i.e., the one receiving while the other transmitting and vice versa, and b) to separate the signals arriving concurrently at the destination using the well-known space division multiple access (SDMA) technique. Numerical results manifest that the proposed model outperforms conventional relaying in terms of outage probability, due to the former´s advantage of higher spectral efficiency.