Analysis of a Mixed Strategy for Multiple Relay Networks

Infrastructure-based wireless communications systems as well as ad hoc networks experience a growing importance in present-day telecommunications. An increased density and popularity of mobile terminals poses the question how to exploit wireless networks more efficiently. One possibility is to use
relay

nodes
supporting the end-to-end communication of two nodes. In their landmark paper, Cover and El Gamal proposed different coding strategies for the single-relay channel. These strategies are the
decode-and-forward
and
compress-and-forward
approach, as well as a general lower bound on the capacity of a single-relay network which relies on the combined application of the previous two strategies. So far, only parts of their work-the decode-and-forward and the compress-and-forward strategy-have been applied to networks with multiple relays. In this paper a generalizing framework for multiple-relay networks is derived using a combined approach of partial decode-and-forward and the ideas of successive refinement with different side information. After describing the protocol structure, the achievable rates for the discrete memoryless relay channel as well as the Gaussian multiple-relay channel are presented and analyzed. Using these results the derived framework is compared with protocols of lower complexity, e.g., multilevel decode-and-forward and distributed compress-and-forward.