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.

频谱感知对于次要认知无线电用户在不干扰主要用户的情况下运行至关重要。次要用户可以通过在它们之间交换本地观测值来单独地或协作地进行频谱感知。本文介绍了个体频谱感知面临的挑战，例如隐藏终端问题、阴影效应、衰落以及硬件限制。该研究还讨论了协作频谱感知所带来的益处。在这项工作中，对最新的协作频谱感知技术进行了详细综述，并介绍了实现这些技术的各种感知方案。我们的综述表明，协作频谱感知可以通过提高频谱效率和提供更好的检测精度来改善认知无线电网络的性能。然而，这些益处是以增加开销流量、功耗、复杂性以及对控制信道的需求为代价的。我们认为，协作感知的挑战将是许多未来有待开展的研究的主题。