With growing number of subscribers for cellular technology the users are in thirst for a better technology which provides higher speed, low latency, consumes low battery life and the list goes on 5G technology has a solution to most of the problems the users are facing with the existing 4G. The requirements of 5G can be bridged by using cognitive radio. CR is a technology in wireless communication where unused frequency spectrum is detected and is used for better spectrum utilization. Here the unused spectrum of the licensed user is detected and is allocated to the unlicensed user. The licensed and unlicensed user are called primary and secondary user respectively. In CRN the secondary users will continuously sense the RF environment. The performance of the CRN depends on the efficiency of the spectrum sensing algorithm. The quality of spectrum sensing is determined by accuracy of signal detection. Signal detection or in other words detection theory is a means to measure the