Cooperative Gain and Cooperative Region Aided Relay Selection for Decode-and-Forward Relaying Protocols

Jianfei CAO  Zhangdui ZHONG  Bo AI  

IEICE TRANSACTIONS on Communications   Vol.E96-B   No.1   pp.190-200
Publication Date: 2013/01/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E96.B.190
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
outage probability,  cooperative gain,  cooperative region,  relay selection,  

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In this paper, we study four simple but fundamental cooperative protocols operating in the decode-and-forward (DF) fashion. Intuitively, finding an appropriate relay for such protocols may greatly improve the outage performance in practice. To this end, we investigate the issue of relay selection in this paper. Specifically, using the asymptotic outage probability, we define and derive the cooperative gain (CG) which quantitatively evaluates the superiority of cooperation over direct transmission. To simplify the process of relay selection, we derive the cooperative region (CR) where a relay is necessarily invoked to aid the communication from source to destination. With the aid of CG and CR, we propose our relay selection algorithm requiring the geographical information rather than the instantaneous channel state information (CSI), and predict the optimal relay locations. In addition, two diversity bounds are also prepared and compared. Finally, both simulations and numerical results are provided on the asymptotic outage probability, CG and CR.