Spectrum sensing in cognitive radio networks: Up-to-date techniques and future challenges

Spectrum sensing is essential to secondary cognitive radio users to operate without interference to primary users. Secondary users can perform the spectrum sensing either individually or cooperatively by exchanging local observations among them. This paper presents individual spectrum sensing challenges such as hidden terminal problem, shadowing, fading, and hardware limitations. The study also discusses the benefits gained by cooperative spectrum sensing. A detailed review of up-to-date cooperative spectrum sensing techniques is given in this work along with the various sensing schemes that implement these techniques. Out review shows that cooperative spectrum sensing can improve the cognitive radio network performance by increasing spectrum efficiency and providing a better detection accuracy. However, the benefits come at the cost of increased overhead traffic, power consumption, complexity, and the need for control channels. We believe that challenges of the cooperative sensing will be the subject of many future studies yet to be done.