Analysis of opportunistic spectrum sharing with markovian arrivals and phase-type service

We develop a general framework for analyzing the performance of an opportunistic spectrum sharing (OSS) wireless system at the session level with Markovian arrivals and phasetype service times. The OSS system consists of primary or licensed users of the spectrum and secondary users that sense the channel status and opportunistically share the spectrum resources with the primary users in a coverage area. When a secondary user with an active session detects an arrival of a primary session in its current channel, the secondary user leaves the channel quickly and switches to an idle channel, if one is available, to continue the session. Otherwise, the secondary session is preempted and moved to a preemption queue. The OSS system is modeled by a multi-dimensional Markov process. We derive explicit expressions for the related transition rate matrices using matrix-analytic methods. We also obtain expressions for several performance measures of interest, and present both analytic and simulation results in terms of these performance measures. The proposed OSS model encompasses a large class of specific models as special cases, and should be useful for modeling and performance evaluation of future opportunistic spectrum sharing systems.