On the Error Probability of Cognitive RF-FSO Relay Networks over Rayleigh/EW Fading Channels with Primary-Secondary Interference

Free space optical (FSO) communication has emerged to provide line of sight connectivity and higher throughput over unlicensed optical spectrums. Cognitive radio (CR), on the other hand, can utilize the radio frequency (RF) spectrum and allow a secondary user (SU) to share the same spectrum with the primary user (PU) as long as the SU does not impose interference on the PU. Owing to the potential of these emerging technologies, to provide full spectrum efficiency, this paper focuses on the mixed CR RF-FSO transmission scheme, where RF communication is employed at one hop followed by the FSO transmission on the other hop in a dual-hop decode-and-forward (DF) configuration. To quantify the performance of the propose

Antenna Selection in MIMO Cognitive AF Relay Networks with Mutual Interference and Limited Feedback

This letter studies antenna selection in amplify-and-forward multiple-input multiple-output cooperative cognitive radio system under mutual primary-secondary interference. Two power allocation methods are adopted at the secondary transmitters, assuming perfect and limited feedback from the primary receiver. For both methods, outage, and error performance analysis is conducted, where simple, closed-form expressions are derived over Rayleigh fading channels. In addition, asymptotic analysis is performed to get insights about the diversity gain and the effects of key parameters, including the primary receiver feedback and the number of the antennas. Our analytical results, which are validated with simulations, show the effective impac

Signal Space Cognitive Cooperation

In this work, a new transmission scheme, signal space cognitive cooperation, is introduced by applying the idea of signal space diversity in an underlay spectrum sharing decode-and-forward multi-relay cooperative network. In the proposed structure, the secondary source signal is rotated by a certain angle and then the source and the secondary best relay transmit different partial representations (the in-phase and the quadrature components) of the rotated signal. As a consequence, two source signal