  Cognitive radio nodes have been proposed as means to improve the spectrum
utilization. It reuses the spectrum of a primary service provider under the
condition that the primary service provider services are not harmfully
interrupted. A cognitive radio can sense its operating environment's conditions
and it is able to reconfigure itself and to communicate with other counterparts
based on the status of the environment and also the requirements of the user to
meet the optimal communication conditions and to keep quality of service (QoS)
as high as possible. The efficiency of spectrum sharing can be improved by
minimizing the interference. The Utility function that captures the cooperative
behavior to minimize the interference and the satisfaction to improve the
throughput is investigated. The dynamic spectrum sharing algorithm can maintain
the quality of service (QoS) of each network while the effective spectrum
utilisation is improved under a fluctuation traffic environment when the
available spectrum is limited.
