Continuous transmit in cognitive radio systems: outage performance of selection decode-and-forward relay networks over Nakagami-m fading channels
Mohammed Ridouani, Aawatif Menouni Hayar, Abdelkrim Haqiq · EURASIP Journal on Wireless Communications and Networking · 2015
Cognitive radio is a promising technology that uses radio spectrum opportunistically and efficiently. In this paper, we present the performance of ‘Always transmit’ strategy, which consists of allowing the cognitive source to transmit over all time slots and in any time slot. Thus, the cognitive source will be able to operate continuously whenever either the primary user is active or absent. The proposed strategy is projected into dual-hop communication systems with decode-and-forward and relay selection over independent but not necessarily identically distributed Nakagami- m fading channels. We derive the closed-form expressions of the outage probability, and we analyze the performance. Simulation results show that the strategy ‘Always transmit + Relay’ outperforms other conventional cognitive radio strategies and the use of relays enhances the performance in deep fading channel.