OFDM-Based Based Cognitive Radio Networks for Spectrum Monitoring Using Energy Ratio Algorithm

Abstract

This paper presents a spectrum mon- itoring algorithm for Orthogonal Frequency Di- vision Multiplexing (OFDM) based cognitive ra- dios by which the primary user reappearance or availability can be detected during the secondary user transmission. The proposed method or tech- nique reduces the frequency with which spectrum sensing must be performed and greatly decreases the elapsed period between the start of a primary transmission and its detection by the secondary network. This is done by sensing the change in signal strength throughout a number of reserved OFDM sub-carriers so that the availability of the primary user is easily detected. Moreover, the OFDM impairments such as power leakage, Narrow Band Interference (NBI), and Inter-Carrier Inter-ference (ICI) are investigated and their impacts are studied. Both analysis and simulation show that the energy ratio algorithm can e ectively and accurately detect the appearance of the primary user. Furthermore, this method achieves more im- munity to frequency-selective fading channels for both single and multiple receive antenna systems, with a complexity that is approximately twice that of a conventional energy detector.Cognitive radios o er the promise of being a disruptive technologies innovation that would enable the future wireless world. Cognitive radios network is programmable wireless devices that could sense their environment and dynamically adapted their transmission wave- form, channel access methods, spectrum used, and networking protocol as needed for better network and application performance