Performance of Adaptive Link Selection With Buffer-Aided Relays in Underlay Cognitive Networks

In this paper, we investigate the performance of a three-node dual-hop cognitive radio network with a half-duplex decode-and-forward buffer-aided relay. We derive expressions for the average rate and symbol error rate (SER) performance of an adaptive link selection based channel-aware buffer-aided relay scheme that imposes peak-power and peak-interference constraints on the secondary nodes, and compare them with those of conventional non-buffer-aided relay and conventional buffer-aided relay schemes for a delay-tolerant system. For a finite-sized buffer, we analyze the performance of a modified threshold-based scheme for fixed-rate transmission. We analyze the tradeoffs between the delay, throughput, and SER. Computer simulation results are presented to demonstrate accuracy of the derived expressions.