Multi-way Communications: An Information Theoretic Perspective

Multi-way communication is a means to significantly improve the spectralefficiency of wireless networks. For instance, in a bi-directional ortwo-way communication channel, two users can simultaneously usethe transmission medium to exchange information, thus achieving upto twice the rate that would be achieved had each user transmittedseparately. Multi-way communications provides an overview on the developmentsin this research area since it has been initiated by Shannon.The basic two-way communication channel is considered first, followedby the two-way relay channel obtained by the deployment of an additionalcooperative relay node to improve the overall communicationperformance. This basic setup is then extended to multi-user systems.For all these setups, fundamental limits on the achievable rates are reviewed,thereby making use of a linear high-SNR deterministic channelmodel to provide valuable insights which are helpful when discussingthe coding schemes for Gaussian channel models in detail. Several toolsand communication strategies are used in the process, including butnot limited to computation, signal-space alignment, and nested-latticecodes. Finally, extensions of multi-way communication channels to multipleantenna settings are discussed.