Spectrum Sensing and Throughput Trade-off in Cognitive Radio under Outage Constraints over Nakagami Fading

The spectrum sensing duration and the secondary user´s achievable throughput trade-off is optimized under outage constraints in a cooperative cognitive radio network over Nakagami fading conditions. The optimum trade-off depends not only on the maximum outage probability allowed by the primary user and the number of cognitive users involved in the sensing but also on the fading operational conditions of the cognitive radio. The parameters of the Nakagami fading distribution can be adjusted to fit different fading environments. The fading parameter (also called shape parameter) of the Nakagami distribution affects the optimum sensing time, which increases when the fading conditions are worse than Rayleigh fading. For the energy detector, the expression for the probability of false alarm is obtained in terms of a new threshold, which is derived considering an outage constraint on the channel-dependent probability of detection. Then, the optimization problem is formulated. Simulation results quantify the effects of different fading parameters on the optimum spectrum sensing duration.