ABSTRACT
The upcoming communication paradigms, in particular, 5G and the Internet of things (IoT) networks, will infer an enormous number of smart objects to join the global network, mostly through wireless communications technologies. Consequentially, considerable wireless traffic density and radio spectrum scarcity are expected. Cognitive radio (CR) technology is a promising solution for improving spectrum utilization to handle the potential increasing traffic of future wireless networks. This chapter explains the concept of this new technology and its various proposed definitions. The primary CR functions are explained, and their related challenges are identified. Spectrum sensing is the most important function in CR. Among several sensing methods proposed for spectrum sensing, there is no single optimized method. In this chapter, the factors that should be considered when choosing the proper sensing method are investigated. The critical issue that hinders the wide adaptation of CR technology is the noticeable QoS degradation caused by an imperfect sensing operation. The authors of this chapter have suggested that a future CR device has to be designed to support various sensing methods so it can switch between them, based on the investigated factors, for better sensing performance and QoS provisioning.
