TITLE:
Optimal Set of Multiple Relays and Distributed Self-Selection in Cooperative Networks
AUTHORS:
Xiaohua Li, Chengyu Xiong, Jeong Kyun Lee
KEYWORDS:
Cooperative Transmission; Amplify and Forward Relaying; Signal to Noise Ratio; Distributed Algorithm; Linear-Fractional Programming
JOURNAL NAME:
Communications and Network,
Vol.5 No.2,
May
10,
2013
ABSTRACT: In this paper we derive analytically the optimal set of relays for the maximal destination signal-to-noise ratio (SNR) in a two-hop amplify-and-forward cooperative network with frequency-selective fading channels. Simple rules are derived to determine the optimal relays from all available candidates. Our results show that a node either participates in relaying with full power or does not participate in relaying at all, and that a node is a valid relay if and only if its SNR is higher than the optimal destination SNR. In addition, we develop a simple distributed algorithm for each node to determine whether participating in relaying by comparing its own SNR with the broadcasted destination SNR. This algorithm has extremely low overhead, and is shown to converge to the optimal solution fast and exactly within a finite number of iterations. The extremely high efficiency makes it especially suitable to time-varying mobile networks.