Hybrid Transmission Scheme for MIMO Relay Channels

To improve the achievable rate for the MIMO channels, we propose a hybrid transmission (HT) scheme that mixes half-duplex decode-and-forward cooperative relaying transmission (DFRH)with direct transmission (DT). In the HT scheme, the source message is divided into two parts: one is transmitted by DFRH scheme and another is transmitted by DT scheme. Precoding and decoding are considered to convert the original MIMO relay channel into several parallel subchannels so that resource allocation can be easily performed. We focus on the spatial subchannel and power allocation problem. The objective of this problem is to maximize the total achievable rate under the constraints of joint total transmission power. Simulation results show that significant capacity gain can be achieved by the HT scheme compared to the DT scheme and the pure DFRH scheme.