A New Adaptive Two Stage Spectrum Sensing Technique in Cognitive Radio System for Different Modulation Schemes

摘要

The aim of this study is to suggests a new two stage spectrum sensing approach. More specifically, a fast spectrum sensing algorithm based on the energy detection is introduced. The proposed system deals with soft decision with multilevel threshold values. Also, constant value of false alarm probability is used to obtain the constant false alarm rate principles. Matlab simulation program is used to obtain the results. In order to evaluate the performance of the proposed adaptive cognitive radio detection system, different modulated digital signals are generated at low SNR values. These different levels of 2FSK, 4FSK, BPSK, QPSK, 8PSK, 4QAM, 16QAM, 64QAM and 256QAM are used together for the first time in this study. The obtained results show excellent performance for the proposed system due to their detection probability of 100% at -15dB for probability of false alarm is 0.1. Different message lengths with different noisy channels such as AWGN and fading are also examined. Numerical results indicate that better performance is achieved by proposed two stage sensing detection compared to the conventional energy detector of the published papers.