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Cooperative spectrum sensing with simple multi-relay switching

To save the power and time of total relay processing and to achieve a higher bandwidth efficiency in relay usage, a simple multi-relay switching scheme is proposed and analyzed for cooperative spectrum sensing, where energy detection is employed for the detection of a spectrum hole. In the cooperative spectrum sensing with relay switching, not all available relays are activated and used at all time. A relay is used only if the strength of faded signal-to-noise ratio (SNR) for its reporting channel to the cognitive destination (CD) is larger than a preset threshold. Otherwise, another switched-to relay is considered and tested for its usage. The probabilities of false alarm and correct detection are derived for independent and identically distributed (i.i.d.) Rayleigh fading channels. The average number of active relays is evaluated for the examination of total required relay processing. Various numerical results are presented for performance illustrations. Based on the numerical results, the proposed scheme can enhance the detection performance in many aspects.