Cooperative Diversity Scheme with Two Relay Stations and Linear Coherent Detection

A new cooperative diversity scheme with two relay stations and linear coherent detection at the destination node is proposed in this paper. We consider that a perfect CSI is available at the destination node, as well to the relay stations, allowing each relay station to perform optimal beamforming. In order to evaluate the effect of a quantized feedback link between the destination node and the relay stations, we also consider that the destination node sends, additionally, b more bits to the relays. Using these b bits, the relay stations can apply a correction factor to the detected symbol and then send it to the destination node which performs a linear coherent detection. In our proposal, the communication between the relay stations is not allowed. The performance of the proposed scheme is compared with the well known MRC receiver technique with four receive antennas in order to show that the proposed and the MRC schemes achieve the same diversity order. In addition, the influence of the number of feedback bits and the SNR between the transmit node and relay stations are also addressed.