Space–Time Diversity Enhancements Using Collaborative Communications

The use of the spatial dimension is known to greatly increase the reliability of quasi-static (i.e., nonergodic) wireless channels. In this paper, it is demonstrated that most of this gain can also be achieved through collaborative communications with single-antenna/multiple-antenna nodes when there is one receiving agent. In particular, for the single-antenna case, communication is considered to take place between clusters of nearby nodes. The existence of collaborative codes 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) is shown. For example, for a single transmitter node with two collaborators and one receiver node, if the collaborators have as little as a 10-dB path loss advantage over the receiver, the penalty for collaboration over traditional space-time systems is negligible.