Research On Spectrum Sensing Technology In Flat Fading Channel

At present,the occupancy rate of wireless spectrum is gradually increasing,and spectrum sensing technology can effectively identify spectrum occupancy information,which is convenient for cognitive radio networks to dynamically plan the spectrum.In addition to the field of cognitive radio,spectrum sensing is also widely used in the field of military reconnaissance.Therefore,it is meaningful to study spectrum sensing methods respectively applicable to civilian and military fields under fading channels closed to actual wireless environment.In this paper,fixed-frequency and frequency-hopping signals under flat fading channels are the main research subjects.Firstly,analyze and improve the fixed frequency signal sensing method.Moreover,compare and analyze the sensing performance of the existing spectrum sensing methods.Secondly,provide a theoretical basis for the spectrum sensing of frequency hopping signals,and performs performance analysis.Finally,based on the FPGA plus DA/AD platform,the signal source plus sensing module is realized.The main research contents of this paper are as follows:Firstly,introduce the single-node and multi-node classical spectrum sensing methods.Based on the single-node spectrum sensing methods,energy detection,cycle feature detection and dual-threshold spectrum sensing are introduced.Moreover,the performance is analyzed,and the sensing methods are simulated based on the MATLAB platform.In the multi-node spectrum sensing methods,several hard decision criteria are introduced.In the flat fading channel,the spectrum sensing algorithm of fixed frequency signal is studied.Firstly,the performance of energy detection under fading channel is verified.Secondly,in order to solve the problem of high computational complexity of the cyclic feature detection algorithm,improvements have been made and extended to fading channels.Combined with the improvement of energy detection,a two-stage spectrum sensing algorithm is obtained,and compared with the existing spectrum sensing algorithm in terms of performance and complexity.To solve the problem that military communication signals are difficult to detect,the spectrum sensing algorithm of frequency hopping signals is studied.The frequency hopping signal sensing method of digital channelization preprocessing plus conventional sensing is analyzed.In addition,using short-time Fourier transform analysis,a new frequency-hopping signal spectrum sensing analysis model is established,which provides a theoretical basis for frequency-hopping signal sensing and reconnaissance,which is verified by simulation analysis.Finally,according to the FPGA plus AD/DA hardware platform,the source plus perception module is implemented.Mainly include link business information,control information development,MATLAB floating/fixed-point algorithm design and FPGA implementation.