Fpga implementation of spectrum sensing techniques for cr standards

Abstract

Radio spectrum is a limited and valuable natural resource in wireless communications. The conventional spectrum allocation policies are causing a serious problem of spectrum scarcity to the emerging wireless technologies. On the other hand, the studies reveal that most of the licensed spectrum is underutilized. For efficient spectrum utilization, FCC is allowing the sharing of the licensed spectrum with unlicensed users. Cognitive radio is a technology which addresses the issue of spectrum sharing with the help of dynamic spectrum access. Spectrum sensing is a fundamental and essential module in cognitive radio which detects the presence of licensed users in the spectrum. To avoid the harmful interference from an unlicensed user to the licensed user, cognitive radio (CR) has to sense the spectrum efficiently so the spectrum sensing has to be carried out effectively. In this thesis, different spectrum sensing methods are analyzed and amongst the energy detection method has been considered for FPGA implementation. The parameters such as probability of false alarm and probability of detection are analyzed from Receiver Operating Curves of energy detection method. The energy detection technique in both time domain and in frequency domain has been implemented. The time domain implementation consists of three modules such as energy detector, threshold estimation and a decision module. The complete energy detection module is downloaded onto Spartan-3E FPGA and the validity of functionality is verified through Chipscope Pro core analyzer .In frequency domain implementation the input samples are transformed into frequency domain using FFT IP core generator. A simple model of covariance based spectrum sensing is also been implemented using HDL design.