Distributed spectrum access algorithm for Cognitive Wireless Network with QoS protection of active users

In this paper, a distributed spectrum access algorithm for Cognitive Wireless Network (CogWN) is proposed. The objective is to maximize the number of admitted Secondary Users (SUs) under the constraint of Interference Temperature (IT) at Measurement Point (MP), while providing AQP (Active users´ Quality of service Protection) at the same time. Here AQP means that the Signal to Interference plus Noise Ratios (SINRs) of all active SUs will not fluctuate below their predetermined thresholds during the process of new SUs´ spectrum access. In addition, an alarm mechanism is introduced into CogWN, which ensures the IT at MP is always below the predefined threshold, so that the communication of primary system is protected from being affected by SUs. Finally, the proposed algorithm is evaluated through extensive simulations, and the results show that it has a better performance than the traditional algorithm.