Relay selection with limited feedback for multiple UE relays

Abstract

When a source has insufficient information about relay-to-destination (R-D) link, like type-2 user equipment (UE) relaying, using average channel gain severely degrades the end-to-end error performance. In this paper, we propose a threshold based relay selection with limited feedback, which has more specific information about R-D link. For a simple case, we consider two adaptive thresholds, where the R-D channel gain is quantized to three levels. Candidate relays whose signal strength exceeds a threshold are divided into two groups according to the threshold, and a source selects the best relay considering the modified harmonic mean of channel gains. We suggest the method of finding optimal thresholds and present the symbol-error rate (SER) performance of M-ary PSK signaling. Simulation results show that relay selection with limited feedback can improve the SER performance, especially in asymmetric link conditions. © 2011 Springer-Verlag.