Interference impact on the outage capacity of a frequency diversity paradigm in cognitive radio networks

A cognitive radio (CR) network is formed by allowing the secondary users to opportunistically access the frequency bands that are idle in time or frequency whenever the primary users (PUs) are not using these bands. In fact, this new technology tries to solve the spectrum scarcity. In this study, with the assumption that the CR 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 CR user´s outage capacity criteria is compared in two structures: one with the use of frequency diversity technique and the other without the use of frequency diversity. After that, the authors will evaluate the total interference power in the primary system and its statistical characterisation. Finally, the permissible ranges of the CRs transmit power by considering the outage probability and interference probability constraints will be obtained in these two structures.