Cognitive Radio Networks, a Key Technology of Future Wireless Communication: Challenges and Opportunities

Abstract

It is a well-known and established fact that the current approach of fixed spectrum allocation, the command-and-control model, makes the spectrum or the finite resource to be grossly underutilized or inefficient. There are so many bands of the spectrum already licensed to users but which in reality are unoccupied at some instance in time thereby creating spectrum holes. These are ‘opportunities’ that could be harnessed. Cognitive Radio (CR) is a promising technology being envisioned to solve the problem of spectrum under utilization and allows for real-time spectrum management. The CR, in a noninterference basis, opportunistically explores the unused channel, thereby ensuring efficient usage of this ‘scarce’ resource. The CR is a sure technology for the next generation wireless systems. In a CR, a licensed user, also called a Primary User (PU), has a priority over the Secondary User (SU) which has no spectrum license. Therefore, at the arrival of a PU, an opportunistic SU vacates the occupied channel and seeks another empty channel to be allocated. In this way, spectral efficiency is greatly enhanced. In this work, we examine the challenges that this new technology is bound to face.