Abstract

In the paper, we focus on modeling and analyzing hierarchical spectrum access, including opportunistic spectrum access (OSA) and concurrent spectrum sharing (CSS). According to the spectrum occupancy by both primary and secondary users, we model the dynamics of OSA as an N-dimension 3N-state Markov process and the dynamics of CSS as an N-dimension 4N-state Markov process. The formulations with service traffics for both models are given, in which imperfect spectrum sensing is considered. Based on proposed models, we deduce system performance metrics such as the blocking probabilities of primary and secondary users, the channel utilization efficiency and so on, with which the performances of OSA and CSS are analyzed and compared. Our research indicates that hierarchical spectrum access doesn't reduce the access opportunities of primary users if the misdetection probability equals the false alarm probability. The CSS has a higher channel utilization efficiency than the OSA but it is more sensitive to the change of service traffics' rates. These results provide some insights on spectrum access optimization.

Paper Details