Cooperative Sensing for Cognitive Radio: A Powerful Access Method for Shadowing Environment

Abstract

Cognitive radio (CR) is an emerging technology developed to overwhelm the problems like underutilization of the spectrum and spectrum scarcity based on the revolutionary ideas. To take control over the spectrum scarcity and underutilization, several bodies headed by the Federal Communications Commission (FCC), have been taking action to make new paradigm of spectrum management. In 2002 report, the FCC has pointed out that more than 70 % of the radio spectrum, is underutilized in certain times or geographic locations. Hence, spectrum scarcity is not attributable to a fundamental lack of spectrum instead because of the waste of static spectrum allocation. The energy detection spectrum sensing is used in this article that is considered to be simple and best method for sensing techniques. In this paper, two major issues of energy detection method, i.e. noise uncertainty and hidden node problem are discussed and solved. To overcome noise uncertainty, M-ary QAM technique is proposed that increases the overall performance with respect to probability of false alarm and probability of missed detection by 3 % at a same latency time. When CR experiences shadowing or fading effect; under such cases, the user cannot distinguish between an unused band and a deep fade, often consider as a hidden node problem. To overcome this problem, cooperative fusion Sensing with a combination of AND and OR logic of a primary user is done by increasing the cognitive/secondary user up to 11. Simulation results using MATLAB shows that both these techniques overcome both the issues and improves significantly the overall Cognitive system performance.