Research On Energy-efficient Spectrum Sensing Method Of Wideband In Cognitive Radio

With the rapid development and wide application of wireless communication technology,the contradiction between the crowded electromagnetic spectrum and the low spectrum utilization is becoming more and more prominent.The emergence of cognitive radio alleviates the problem.On the other hand,with the concern of energy consumption and environmental degradation,how to reduce the energy consumption of the communication system and realize the green communication become an urgent problem to be solved.Therefore,it is of great significance to study the strategies and methods which can not only improve the spectrum utilization but also reduce the energy consumption of communication by combining cognitive radio and energy-efficient communication.In this thesis,we focus on the research of energy-efficient broadband spectrum sensing method in cognitive radio system,the main work and contributions are summarized as follows:1.In view of the impact of sensing time on the sensing energy consumption,an energy-efficient spectrum sensing method based on the optimization of sensing time is proposed.Based on the periodic spectrum sensing strategy,a function expression of sensing energy consumption on sensing time is deduced,and the optimization model of sensing energy consumption is established.By solving this optimization problem,a closed expression of sensing time that satisfies the specific sensing performance and the minimum energy consumption is derived,finally an expression of minimum energy consumption on the target sensing performance is obtained.The simulation results validate the effectiveness of the proposed spectrum sensing method in reducing sensing energy consumption.2.In view of the impact of decision threshold on the sensing energy consumption,an energy-efficient spectrum sensing method based on the optimization of decision threshold is proposed.The method is also based on the periodic spectrum sensing strategy,a relational expression of sensing energy consumption on decision threshold is deduced,and the optimization model of sensing energy consumption under the specific error decision probability is established.By solving this optimization problem,the minimum sensing energy consumption that satisfies the specific error decision probability is obtained.Under the condition of satisfying the specific error decision probability,the simulation results show that the sensing energy consumption based on the optimization of decision threshold is better than that on the minimum error decision probability and that is non-optimized.3.In view of the defects of the existing periodic spectrum sensing strategy in the aspect of sensing energy consumption,an energy-efficient spectrum sensing method based on quickest sensingis proposed.In this method,changes of the probability density function are used to determine whether the primary user appears.The judgment of the primary user appears is obtained once the pdf of the received signal changed,then the secondary user immediately stops spectrum sensing and switches to other idle channel to transmit data.So it can optimize sensing energy consumption by reducing sensing delay.And mathematical expressions of the average sensing energy consumption under two channel models of Gaussian and Rayleigh channels are derived.The simulation results show that compared with the traditional periodic spectrum sensing strategy,the proposed quickest spectrum sensing method can effectively save sensing energy consumption.