Energy Detection for Spectrum Sensing in Cognitive Radio

Spectrum scarcity is one of the biggest challenges that the currentwireless sensor network is facing. With the exciting progress of wirelesssensor network (WSN) within 5 to 10 years, the world will be full of low power wireless sensor devices. Due to the independent design and development, together with the unexpected dynamics during deployment of co-existing networks and devices, the limited frequency spectrum will be extremely crowded. To address this challenge, cognitive radio has emerged as the key technology, which enables opportunistic access to the spectrum.

In this paper one of the spectrum sensing method Energy detection is implemented in MATLAB to determine the availability of vacant spectrum of licensed band. The straight forward method for detecting unknown signals is energy detection. When primary user is assumed to be unknown to the secondary receiver’s detector, it will become an energy detector, also referred to as radiometers. The energy of a received wave form can be measured by squaring the output of band pass filter with a bandwidth W, and then integrating the received power over a time interval T. The output of the integrator is compared with a predefined threshold to determine presence or absence of primary user.