Research On Dynamic Spectrum Access In Cognitive Radio

Today's wireless communication systems are characterized by a fixed spectrum assignment policy. The utilization of spectrum is strictly limited by the division and authorization, resulting in a serious waste of spectrum resources. As an important application of cognitive radio, dynamic spectrum access (DSA) can improve the spectrum efficiency by timely accessing spectrum holes according to temporal and spatial traffic statistics during the communications.This paper mainly researches opportunistic spectrum access (OSA) algorithm based on Partially Observable Markov Decision Process (POMDP). Aiming at the selfish of the greedy approach in OSA networks with multiple secondary users, the improved algorithm, named distributed cooperative spectrum access algorithm based on POMDP, is given which adopts the concepts of distributed coordination and cooperative spectrum access. Simulation shows that the improved algorithm increases the throughput of the network and the efficiency of spectrum utilization, while there is no significant increase in complexity comparing to the greedy algorithm.