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Direct Link-Aware Optimal Relay Selection and a Low Feedback Variant for Underlay CR

Das, Priyanka and Mehta, Neelesh B (2015) Direct Link-Aware Optimal Relay Selection and a Low Feedback Variant for Underlay CR. In: IEEE TRANSACTIONS ON COMMUNICATIONS, 63 (6). pp. 2044-2055.

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Official URL: http://dx.doi.org/ 10.1109/TCOMM.2015.2432026


Cooperative relaying combined with selection has been extensively studied in the literature to improve the performance of interference-constrained secondary users in underlay cognitive radio (CR). We present a novel symbol error probability (SEP)-optimal amplify-and-forward relay selection rule for an average interference-constrained underlay CR system. A fundamental principle, which is unique to average interference-constrained underlay CR, that the proposed rule brings out is that the choice of the optimal relay is affected not just by the source-to-relay, relay-to-destination, and relay-to-primary receiver links, which are local to the relay, but also by the direct source-to-destination (SD) link, even though it is not local to any relay. We also propose a simpler, practically amenable variant of the optimal rule called the 1-bit rule, which requires just one bit of feedback about the SD link gain to the relays, and incurs a marginal performance loss relative to the optimal rule. We analyze its SEP and develop an insightful asymptotic SEP analysis. The proposed rules markedly outperform several ad hoc SD link-unaware rules proposed in the literature. They also generalize the interference-unconstrained and SD link-unaware optimal rules considered in the literature.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA
Keywords: Underlay cognitive radio; interference constraint; cooperative communications; relays; amplify-and-forward; selection; symbol error probability; feedback
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited: 19 Jul 2015 09:38
Last Modified: 19 Jul 2015 09:38
URI: http://eprints.iisc.ac.in/id/eprint/51879

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