Cognitive radio is an intelligent network which addresses the availability of radio spectrum in order to enable dynamic spectrum access. This paper is based on engineering model for electromagnetic spectrum, which deals with current scarcity-based regulatory model. It is an intelligent platform through which static frequency allocations can done to dynamic, intelligent, and instantaneous frequency negotiations and assignment. Various detection models were discussed to make the radio spectrum abundance model possible, and a brief discussion on the architecture of mobile network. It was identified as a promising solution to the limit less need of spectrum and the main idea behind is for dynamic access of unused spectrum for communication. Its play a vital role for dynamic utilization of idle spectrum without affecting the rights of primary users, so that the services can be available for different or for other services. In this unused spectrum can be share in order to achieve a prominent goal for avoiding the cost of usage of spectrum. It also helps in improving the utilization of spectrum resources. In order to meet the critical requirements of the fifth generation (5G) mobile network, especially the Wider-Coverage, Massive-Capacity, Massive-Connectivity, and Low-Latency four application scenarios, the spectrum range used in 5G will be further expanded into the full spectrum era, possibly from 3 GHz to 300 GHz.