Collaborative diversity enhancements for wireless communications

The use of the spatial dimension is known to greatly increase the reliability of quasi-static (non-ergodic) wireless channels. In this paper we demonstrate that most of this gain can also he achieved through collaborative communications with single-antenna/multiple-antenna nodes when there is one receiving agent. In particular, for the single antenna case, we consider communication to take place between clusters of nearby nodes. We show the existence of collaborative codes for communications for which the intra-cluster negotiation penalty is in principle small and almost all the diversity gain of traditional space-time codes may be realized. For example, for single transmitter/receiver nodes with two collaborators that have as little as 10 dB path loss advantage over the receiver, the penalty for collaboration over traditional space-time systems is negligible.