MIMO relay channel

The approximate capacity of the MIMO relay channel

Xianglan Jin and Young-Han Kim

Capacity bounds are studied for the multiple-antenna complex Gaussian relay channel with t_1 transmitting antennas at the sender, r_2 receiving and t_2 transmitting antennas at the relay, and r_3 receiving antennas at the receiver. It is shown that the partial decode–forward coding scheme achieves within min(t_1,r_2) bits from the cutset bound and at least one half of the cutset bound, establishing a good approximate characterization of the capacity. A similar additive gap of min(t_1+t_2,r_3)+r_2 bits is shown to be achieved by the compress–forward coding scheme. The corresponding results for time-division half-duplex relay channels are also established.