Fifth Generation (5G) and Cognitive Radio (CR) are considered to be the future advancements in wireless technology. The ever increasing number of smart network devices may obsolete latest 4G technology for handling bandwidth allocation to a large number of smart devices. To meet with this challenging need for rapid and efficient data transfer over such devices, requires next generation mobile technology. 5G technology is anticipated to offer appropriate solutions to such issues in literature. High data rates can be achieved by using 5G, however, to make such futuristic technology realistic, is a real challenge. This challenging goal can be achieved by efficient utilization of the bandwidth in allocated spectrum. CR is an intelligent radio which has inherent adaptive procedures. It reuses the frequency when primary user is absent and works on principle of dynamic frequency allocation. CR is one of the key enabling technology for 5G networks which allows nodes to evaluate and manage underused licensed channels. It has brought benefits to a CR based 5G cellular networks which include ability to adapt dynamicity of a network, deals with the spectrum scarcity issue and operates in heterogeneous environment. It also provides intelligent solutions and self-governing capabilities to assist 5G key functions especially in smart beamforming. In this paper we present numerous benefits of 5G technology, enabling technologies of 5G, its challenges and proposed solutions. Furthermore, CR alongwith spectrum sensing techniques are also discussed in detail. Finally, CR based 5G technology is investigated with the view to explore both technologies jointly and to present a comprehensive overview which will invigorate new research initiatives in this exciting field.