Cognitive Radio for 5G Wireless Networks
Olayinka Adigun, Mahdi Pirmoradian, Christos Politis · 2015
Demand for 5G cells is driven by consumer demand where traffic is doubling each year. Now industry is preparing for a bigger challenge, an astounding 1000-fold increase in data traffic expected in this decade. This sets the stage for enabling 5G technology that delivers fast and cost-effective data connectivity, whilst minimising the deployment cost. Despite the success of small cells and MIMO in 4G systems, there is no single technology advance that can meet this traffic demand. In fact, today's technology roadmaps depict different mixes of spectrum (Hertz), spectral efficiency (bits per Hertz per cell) and small cells (cells per square kilometre) as a stepping stone towards meeting this ambitious target. Traditionally, purchasing additional spectrum has been a stopgap solution towards satisfying new Quality of Service demands and coping with extra load on the network. This will also continue to be a solution, as technology capability reaches the ceiling. Therefore, targeting new spectrum availability and knowing how to use this effectively becomes of the essence, particularly in an era where spectral resources are scarce and at a premium. Investigations from the Spectrum Policy Task Force (SPTF) show that 85% of current allocated radio frequency bands are either partially or completely unused at different times across geographical areas, further compounding the drive for the main challenges facing the spectral world. Experts are interested in tackling approaches to more flexible and effective use of radio spectrum. A number of technologies and techniques have been identified as suitors for enabling 5G wireless networks across heterogeneous spectrum, among them is cognitive radio technology. This chapter provides an insight into the key challenges facing cognitive radio as we enter the 5G era.