Spectrum Sensing in Cognitive Radio Communication

Nowadays, the radio resources and particularly the spectrum are considered a very precious resource as spectrum is limited and according to some research it has been found that only few percentages of spectrum is being utilized and rest of the spectrum get wasted, due to this fact a considerable research has been conducted recently for finding suitable and efficient ways to use the radio spectrum. The research results suggest that the efficient use of the radio resources needs radio systems with high intelligence and capabilities. This radio system was called “Cognitive Radio”. The word Cognitive Radio was firstly described by Joseph Mitola. Cognitive Radio is a radio capable of analyzing the environment (as channels and users) and efficient way of using the available spectrum and adapting all of its operation parameters. It is still an open novel approach that is expected to solve the limitations of current systems. The principle for cognitive radio (CR) network regards the cognitive radio users as visitor in spectrum they occupy. They occupy the idle channel without causing interference with primary user and leave the channel when primary user activity is detected. The successful operation of these principles relies on the CR users’ ability to be aware of their surroundings, which is done by spectrum sensing methods. The main reason for introducing the cognitive radio is the inefficient use of the radio resources and particularly the spectrum. Spectrum sensing is a challenging task in cognitive radio communication; it means to sense the presence or absence of primary user. Keyword-Spectrum sensing, Matched filter, energy detection, cognitive user, cooperative detection.