Adaptive spectrum sensing scheme with punishing mechanism in cognitive radio networks

A cognitive radio(CR) system exploits spectrum bands that primary users (PUs) are licensed to use. The CR perform spectrum sensing to find spectrum opportunities. In cognitive radio networks, secondary users (SUs) must sense the licensed channel at proper time in order to avoid interfering with the primary users, while SUs must also transmit data effectively. In conventional spectrum sensing schemes, the sensing time was fixed, which required a long sensing time to detect the weak signal of the PUs. In this paper, basing on the double-threshold energy detection algorithm, we propose an adaptive spectrum sensing scheme with punishing mechanism(ASSP). The scheme adaptively adjusts the sensing time and two thresholds according to the current and previous sensing results. The scheme can not only decreases the sensing cost but also improves the sensing performances. Besides, in order to further decrease the sensing cost and increase the channel utilization ratio, a punishing mechanism is given. The simulation results show that the adaptive scheme significantly outperforms the conventional schemes.