Abstract:

In the frame structure design of cognitive ratio systems, if the data sending time is set unreasonably, it is possible for secondary users to suffer much interference and the lost access opportunity. Under the exponentially distributed assumption based on the primary user activity, an interference model and a lost access opportunity model for secondary users are derived. The models ensure that the interference time and the lost access time are less than a specified percentage with a high probability. Then a theoretical framework about frame duration is developed to limit the interference and lost access opportunity ratio. Simulation results show that the frame structure developed in such a way can effectively ensure the secondary user’s access time, the higher sensing efficiency and lower interference rates.