Cognitive radio for 5G wireless networks

1000x data challenge: 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 deliver fast and cost-effective data connectivity, whilst minimizing 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. This chapter targets the spectrum dimension, and targets spectrum availability, and approaches through flexible use of spectrum in order to provide a step towards more energy compliant mobile networks, and optimised used of spectrum in era where spectrum is a scarce resource are a premium. How the spectrum will be allocated and managed has resulted in conflicting spectrum requirements across the telecommunication industry; indeed proper management of the frequency spectrum is important in maximising its value to society. Exploiting this unused spectrum effectively and efficiently are challenges that need to be solve