Dynamic Channel Selection Algorithm for Cognitive Radios

The scarcity of spectrum has become a major bottleneck of the development of next generation radio systems. Cognitive radio (CR) is a promising solution to improve the utilization of the radio spectrum. That is, spectrum efficiency can be increased significantly by giving opportunistic access of the frequency bands to a group of cognitive users to whom the band has not been licensed. In this paper, based on the a two-phase channel and power allocation scheme proposed by A. T. Hoang etc. , we present a dynamic spectrum sharing algorithm for cognitive radio network. In the scheme proposed by A. T. Hoang etc. , they consider a cognitive radio network that consists of multiple cells and the system throughput is defined as the total number of subscribers that can be simultaneously served. In this paper, we consider a cognitive radio network as self-organizing network. Furthermore, the throughput is defined as the average probability of success transmission. In the proposed algorithm, for each available channel, TDMA frame is divided into N time slots, and each active cognitive user is assigned one transmission slot different from those of other active cognitive users in each frame. It allows an active cognitive user utilize the slots pre- assigned to the other active cognitive users under a range of values for accessing probability. We evaluate the performances of the dynamic spectrum sharing algorithm for different average number of active cognitive users and different number of available channels.