Cooperative communications with relay selection for wireless networks: design issues and applications

Relay selection schemes for cooperative communications to achieve full cooperative diversity gains while maintaining spectral and energy efficiency have been extensively studied in recent research. These schemes select only the best relay from multiple relaying candidates to cooperate with a communication link. In this paper, we review recently proposed cooperative communication protocols which integrate with relay selection mechanisms. The key design issues for relay selection mechanisms, e.g., relaying candidate selection, optimal relay assignment, and cooperative transmission, are identified. We further discuss the challenges of optimal relay assignment in multi-hop wireless sensor networks, and present the potential applications of cooperative communications with relay selection in such networks. Future research directions are outlined, e.g., the issues of service differentiation and system fairness in cooperative communication systems, and the joint use of game theory and machine learning techniques in relaying candidate selection and optimal relay assignment mechanisms for efficient allocation of network resources. Copyright c © 2007 John Wiley & Sons, Ltd.