Investigations on Performance Analysis of Cognitive Radio based NOMA Systems

Abstract

Licensing authorities are responsible for regulating the radio frequency (RF) spectrum, newlinewhich is a natural resource. As a result of an increasing trend in the utilization of newlinewireless devices and the subsequent allotment of spectrum, RF spectrum is becoming newlineincreasingly scarce. However, recent studies have demonstrated that the majority of newlinethe spectrum that is available is not being exploited to its maximum potential at any newlineone moment or location. Cognitive radio (CR) is a cutting-edge technology that has newlinebeen designed to enhance spectrum utilization by making use of spectrum opportunities newlinewhich are perceived as gaps in the radio band that is available. It is possible for newlinethe CR users or secondary users (SUs) to utilize the spectrum assigned to licensed or newlineprimary users (PUs) without affecting the performance of the PUs. Because of this notion,the efficiency with which spectrum is utilized is considerably increased. Spectrum newlinesensing is one of the most significant aspects of CR technologies because it is vital in identifying the existence of PUs precisely and fairly to determine the accessibility of spectral gaps. In wireless applications, it is very crucial to evaluate the availability of an active communication link when the primary user signal is uncertain. A suitable option in these kinds of circumstances is to make use of an energy detector (ED), which is a device that measures the amount of energy contained in the waveform that has been received throughout a period that has been seen. Due to the time-varying nature of wireless newlinechannels, which includes fading and shadowing, it is quite challenging to accurately detect gaps in the spectrum. Because of the extreme multipath fading that occurs in the wireless sensing channel between a cognitive radio user and a PU, the CR user s ability to identify the existence of the PU may be compromised. This is the core of cooperative spectrum sensing (CSS), which allows multiple CR users to cooperate with one another by sharing their sensing information on the activity sta