Comparison of Low-Complexity Diversity Schemes for Dual-Hop AF Relaying Systems

Abstract

Abstract-This correspondence investigates the performance of two low-complexity combining schemes, which are based on one-phase or two-phase observation, to mitigate multipath fading in dual-hop amplify-and-forward (AF) relaying systems. For the one-phase based combining, a single-antenna station is assumed to relay information from multiple-antenna transmitter to multiple-antenna receiver, and the activation of the receive antennas is performed adaptively based on the second hop statistics, regardless of the first hop conditions. On the other hand, the two-phase based combining suggests using multiple single-antenna stations between the multiple-antenna transmitter and the single-antenna receiver, where the suitable set of active relays is identified according to the pre-combining end-to-end fading conditions. To facilitate comparisons between the two schemes, formulations for the statistics of the combined signal-tonoise ratio (SNR) and some performance measures are presented. Numerical and simulation results are shown to clarify the tradeoff between the achieved diversity-array gain, the processing complexity, and the power consumption.