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In this paper, we derive closed-form expressions for the average symbol error probability (SEP) of arbitrary rectangular I X J-ary quadrature amplitude modulation (QAM) in cooperative amplify-and-forward (A&F) relaying systems, when no direct line-of-sight exists between the source and the destination nodes and when the links(More)
We consider a dual-hop cooperative spectrum-sharing system with multiple relays that are available to opportunistically help the secondary communication system. In this primary/secondary cooperative system, we propose using a reactive relay selection (RRS) technique at the secondary system in which the best relay is chosen based on both the first and second(More)
In this paper, we use a distributed Zero Forcing Beamforming (ZFB) method in cognitive radio relay networks in an effort to enhance the spectrum efficiency and improve the performance of the cognitive (secondary) system. In particular, we consider a spectrum sharing system where a set of decode-and-forward (DF) relays are employed to help a pair of(More)
Complex computing systems, including clusters, grids, clouds and skies, are becoming the fundamental tools of green and sustainable ecosystems of future. However, they can also pose critical bottlenecks and ignite disasters. The complexity and high number of variables could easily go beyond the capacity of any analyst or traditional operational research(More)
—Cognitive radio technology offers tremendous potential to improve the utilization of the radio spectrum by efficiently reusing and sharing the licensed spectrum bands, as long as the interference power inflicted on the primary users of the band remains below a predefined threshold level. In this paper, we investigate the outage capacity gains offered by(More)