Cooperative Regions and Partner Choice in Coded Cooperative Systems

Z. Lin, E. Erkip, A. Stefanov
2006 IEEE Transactions on Communications  
User-cooperation is an efficient approach to obtain diversity in both centralized and distributed wireless networks. In this paper, we consider a coded cooperative system under quasi-static Rayleigh fading and investigate the partner choice problem. We find conditions on the inter-user and user-to-destination channel qualities for cooperation to be beneficial. Using frame error rate (FER) as a metric, we define the user cooperation gain (G) for evaluating the relative performance improvement of
more » ... ance improvement of cooperative over direct transmission when a particular channel code is used. We introduce the cooperation decision parameter (CDP) which is a function of user-to-destination average received signal to noise ratios (SNRs) and demonstrate that whether cooperation is useful or not (G > 1 or G < 1) depends only on the CDP, not the inter-user link quality. We use an analytical formulation of the CDP to investigate user cooperation gain and provide insights on how a user can choose among possible partners to maximize cooperation gain. We first consider the asymptotic performance when one or both partners have high average received signal to noise ratio (SNR) at the destination. We then provide conditions on user and destination locations for cooperation to be beneficial for arbitrary SNR's. We illustrate these cooperative regions and study geometric conditions for the best partner choice. We also define the system cooperation gain and illustrate cooperation benefits for both users. All of our theoretical results are verified through numerical examples.
doi:10.1109/tcomm.2006.873058 fatcat:slb6q3z7wzaxtc7a5vt5cvkbny