Review of Spectrum Sensing Techniques in Cognitive Radio Networks

Most frequency spectrum bands are licensed to certain services to avoid the interference between various networks but measurements of spectrum occupancy show that only portions of the spectrum band are fully efficiently used. Cognitive Radio (CR) is a future radio technology that is aware of its environment, internal state and can change its operating behaviour (transmitter parameters) accordingly. Through this technology the unlicensed users can use the underutilized spectrum without any harmful interference to the licensed users. Its key domains are sensing, cognition and adaptation. The spectrum sensing problem is one of the most challenging issues in cognitive radio systems to detect the available frequency bands. In this paper we have implemented various transmitter detection techniques: Energy detection, Matched filter and Cyclostationary feature detection in MATLAB. Along with other techniques to enhance the detection performance of the conventional Energy detector. The Implementation is based on BPSK and QPSK modulation schemes under various SNR values for AWGN noisy channel with Rayleigh fading. The techniques are compared in term of sensing time, detection sensitivity and the ease of implementation.