Opportunistic Feedback and User Selection for Multiuser Two-Way Amplify-and-Forward Relay in Time-Varying Channels

Yong-Up JANG

IEICE TRANSACTIONS on Communications   Vol.E96-B    No.10    pp.2661-2667
Publication Date: 2013/10/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E96.B.2661
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
opportunistic feedback,  user selection,  outage probability,  two-way relay channel,  amplify-and-forward,  time-varying channels,  

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This paper proposes an opportunistic feedback and user selection method for a multiuser two-way relay channel (MU-TWRC) in a time-varying environments where a base station (BS) and a selected mobile station (MS), one of K moving MSs, exchange messages during two time slots via an amplify-and-forward relay station. Specifically, under the assumption of perfect channel reciprocity, we analyze the outage probabilities of several channel feedback scenarios, including the proposed scheme. Based on the analysis, the transmission rates are optimized and the optimal user selection method is proposed to maximize the expected sum throughput. The simulation results indicate that, with opportunistic feedback, the performance can be significantly improved compared to that without feedback. Moreover, the performance is nearly identical to that with full feedback, and close to the case of perfect channel state information at BS for low mobility MSs.