Open Access

Routing and Power Allocation in Asynchronous Gaussian Multiple-Relay Channels

EURASIP Journal on Wireless Communications and Networking20062006:056914

DOI: 10.1155/WCN/2006/56914

Received: 31 October 2005

Accepted: 2 May 2006

Published: 3 July 2006


We investigate the cooperation efficiency of the multiple-relay channel when carrier-level synchronization is not available and all nodes use a decode-forward scheme. We show that by using decode-forward relay signaling, the transmission is effectively interference-free even when all communications share one common physical medium. Furthermore, for any channel realization, we show that there always exist a sequential path and a corresponding simple power allocation policy, which are optimal. Although this does not naturally lead to a polynomial algorithm for the optimization problem, it greatly reduces the search space and makes finding heuristic algorithms easier. To illustrate the efficiency of cooperation and provide prototypes for practical implementation of relay-channel signaling, we propose two heuristic algorithms. The numerical results show that in the low-rate regime, the gain from cooperation is limited, while the gain is considerable in the high-rate regime.


Authors’ Affiliations

Department of Electrical Engineering, University of Hawaii at Manoa


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© Z. Yang and A. Høst-Madsen 2006

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.