Performance of modified TAS/OSTBC schemes in dual-hop relay systems in the presence of feedback errors

Abstract

This paper proposes an amplify-and-forward (AF) relay scheme in which the first transmission link (from source to relay) employs modified transmit antenna selection (TAS)/orthogonal space-time block coding (OSTBC) that provides reduced feedback-rate and robust error performance in the presence of feedback errors (FEs) when compared to the conventional TAS/OSTBC (C-TAS/OSTBC), and the second link (from relay to destination) performs maximal-ratio combining at the destination node. The error probability performance of the proposed dual-hop AF relay scheme in Nakagami fading channels has been examined via Monte Carlo simulations. In addition, the approximate error probability expressions related to the investigated scheme have been derived by using high signalto-noise (SNR) approaches. We have shown that the modified TAS/OSTBC (M-TAS/OSTBC) scheme employed at the first transmission link provides full diversity order and considerable error performance as the C-TAS/OSTBC scheme in ideal feedback cases and also achieves more robust error performance in the presence of erroneous-feedback channels facing both fading effect and additive white Gaussian noise. Thus, by employing the M-TAS/OSTBC scheme in the first hop, the overall error performance of the dual-hop AF relay scheme has been enhanced that would result in reductions on the values of average SNR required to achieve a specified symbol error rate goal. © 2014 Elsevier B.V., All rights reserved.