Performance analysis of opportunistic frequency diversity strategy in cognitive radio systems

Cognitive radio is a new technology that solves the problem of spectrum scarcity. In this technology, secondary users, users that do not have license to use the spectrum, can access the frequency bands that are idle in time or frequency whenever the primary users (PUs), users that have license to access the spectrum, are not using these bands. So, cognitive radio networks improve the spectrum utilization. In this paper, with the assumption that the secondary users operate in a wideband communication system, first the bandwidth of the system is divided into some equal parts that are larger than the coherent bandwidth of the channel, and then the capacity of the channel by considering the secondary user's outage capacity criteria is compared in two structures: one with the use of frequency diversity technique and other without the use of frequency diversity.