A discrete-time model for multichannel opportunistic spectrum access based on preempted queuing

Abstract

We consider the issue of opportunistic spectrum access in temporal domain, in which secondary user seeks spectrum vacancies between bursty transmissions of the primary user to communicate. Since spectrum sensing and data transmission can not be performed simultaneously in the same channel, secondary user employs a sense-then-transmit strategy to detect the presence of the primary user before accessing the licensed channel. Consequently, secondary user transmission is periodically suspended for spectrum sensing. To capture the discontinuous transmission nature of secondary user, we introduce a discrete-time queuing subjected to bursty preemption to describe the behavior of secondary user. The bursty preemption is an abstraction of temporal channel unavailability due to the bursty appearance of the primary user. Under the discrete-time queuing framework, we analyze the performance of opportunistic spectrum access in terms of packet completion slots, secondary user throughput and packet delay. In addition, the stability of the secondary system is studied. Finally, simulation results validate our theoretical approaches and reveal that the proposed model can be widely used to optimize the performance of the opportunistic spectrum access system.