Cooperative Wireless Systems: A Diversity-Multiplexing Tradeoff Perspective
Melda Yüksel, Elza Erkip · arXiv (Cornell University) · 2006
We consider a general multiple antenna network with multiple sources, multiple destinations and multiple relays in terms of diversity-multiplexing tradeoff (DMT). We examine several projections of this most general problem taking into account the network geometry (clustered or non-clustered), the processing capability of the relays (half-duplex or full-duplex) and the number of antennas the nodes have. We first study a system with a single source-destination pair and multiple relays, each node with a single antenna, and show that even under the idealistic assumption of full-duplex relays and a clustered network, this virtual multi-input multi-output (MIMO) system can never fully mimic a real MIMO DMT. We provide communication strategies that achieve the best DMT of this relay system. We extend our work to cover cooperative systems with multiple sources and multiple destinations and show that the same limitation is still in effect. We next study the relay channel with multiple antenna nodes for full-duplex relays to understand the effect of increased degrees of freedom in the direct link. We find DMT upper bounds and investigate the achievable performance of decode-and-forward (DF), and compress-and-forward (CF) protocols. Our results suggest that while DF is DMT optimal when all terminals have one antenna each, it may not maintain its good performance when the degrees of