Spectrum Sensing Limitations in Cognitive Radio Networks

Abstract

As the number of wireless devices is increasing daily, the radio frequency spectrum is becoming more crowded. Moreover, due to the stochastic nature of wireless communications technologies, some frequency bands which are allocated to services or users can be underutilized. On the other hand, some users may not be able to access the medium as all the frequency bands have been already allocated to different users. Cognitive radio has gained a lot of interest in the past few years as it tackles the problem of spectrum scarcity by taking advantage of spectrum holes that are available in the frequency spectrum. Spectrum Sensing is the tool that cognitive radio nodes use to find such holes. A cognitive radio node senses the frequency band, and if it is found to be free, uses it to transmit and receive data. There are two main sensing schemes, Energy Detection, and cooperative sensing. In this paper, we give an overview of these two main schemes focusing on their limitations and ways to optimize their performance in cognitive radio networks.