Principles and challenges of cooperative 12 spectrum sensing in cognitive radio networks

Abstract

Cognitive radio (CR) technology is a promising solution to the inevitable problem of spectrum scarcity and underutilization. Cognitive radios can perform spectrum sensing, dynamically identify unused spectrum, and opportunistically utilize those spectrum holes for their own transmission. Cognitive radio technology is also a key concept suggested to be part of the fifth generation of cellular wireless standards (5G). Efficient spectrum sensing is crucial to the effective deployment of CR networks. Cooperative spectrum sensing (CSS) schemes can significantly improve the sensing accuracy of CR networks by exploiting multiuser spatial diversity. However, the cooperative gain can be impacted by factors such as the detection performance of each secondary user (SU) and the fusion techniques used to combine the secondary users' decisions. Moreover, CSS incurs cooperation overhead that may deteriorate its overall performance. In this chapter, we provide a comprehensive survey on the different factors that contribute to the efficient design of CSS schemes for cognitive radio networks. We specifically focus on the elements of cooperative sensing that can leverage the achievable cooperative gain, limit the cooperation overhead, or provide trade-off between the gain and overhead such as the number of channels sensed in each sensing period, the selection of secondary users, the selection of the fusion scheme, and the correlation between the cooperating secondary users. We also highlight key open research challenges in cooperative spectrum sensing.