Achieving Joint Diversity in Decode-and-Forward MIMO Relay Networks with Zero-Forcing Equalizers

Wireless MIMO relay networks have received significant interests in recent years. However, most MIMO relay techniques require high complexity equalizers and error free forwarding at the relay to collect diversity. In this paper, we propose high-rate and low-complexity decode-and-forward (DF) MIMO relay designs that achieve cooperative diversity, receive diversity or joint diversity. We introduce a power-scaling strategy for MIMO relays to enable cooperative diversity. Zero-forcing equalizers are employed at both relay and destination to maintain low-complexity. We also develop a channel-controlled ARQ scheme to collect receive diversity. Through mathematical analysis, we prove the diversity order achieved by each proposed design and numerical simulations confirm the theoretical claims.