Effect of Imperfect Spectrum Sensing on Slotted Secondary Transmission: Energy Efficiency and Queuing Performance

In cognitive radio communication system, unlicensed secondary user (SU) can opportunistically transmit over the under-utilized spectrum of primary user. With interweave implementation, SU performs spectrum sensing on the target frequency band to detect transmission opportunity. Sensing errors can greatly affect the performance of secondary transmission. In this paper, we propose a discrete-time Markov model to characterize slotted secondary transmission process with imperfect spectrum sensing. The stationary distribution is then applied to total collision probability evaluation and energy efficiency optimization for secondary transmission. Assuming that SU adopts adaptive transmission, we also evaluate the queuing performance of slotted secondary transmission, based on a 2-D finite-state Markov chain. Selected numerical results are presented to illustrate the mathematical formulation and to validate our analytical results. We show that false alarm has significant effect on the secondary throughput, whereas miss detection only notably reduces the secondary throughput when the traffic intensity is low.