  The explosive increase in number of smart devices hosting sophisticated
applications is rapidly affecting the landscape of information communication
technology industry. Mobile subscriptions, expected to reach 8.9 billion by
2022, would drastically increase the demand of extra capacity with aggregate
throughput anticipated to be enhanced by a factor of 1000. In an already
crowded radio spectrum, it becomes increasingly difficult to meet ever growing
application demands of wireless bandwidth. It has been shown that the allocated
spectrum is seldom utilized by the primary users and hence contains spectrum
holes that may be exploited by the unlicensed users for their communication. As
we enter the Internet Of Things (IoT) era in which appliances of common use
will become smart digital devices with rigid performance requirements (such as
low latency, energy efficiency, etc.), current networks face the vexing problem
of how to create sufficient capacity for such applications. The fifth
generation of cellular networks (5G) envisioned to address these challenges are
thus required to incorporate cognition and intelligence to resolve the
aforementioned issues.
