Research On The Suppression Of Narrowband Interference In PCSS System

This research is supported by the university cooperation project “The Research of Key Technology of Parallel Combinatory Spread Spectrum Communication System” of The 54 th Research Institute of China Electronics Technology Group Corporation.Project Number:KX132600013/ITD-U13006.Spread Spectrum Technology is widely used in military confrontation and civil communication rely on its high electromagnetic hidden,high adaptability to wireless channel and multiple access capability.Compared to the traditional Direct Sequence Spread Spectrum,Parallel Combinatory Spread Spectrum which was developed from the Soft Spread Spectrum has advantages of strong information transfer capability and high bandwidth efficiency.It would have a broad application prospect.The affect of Narrowband interference would be a unavoidable problem for communications systems,no mater in military communication or civil communication.In order to improve the anti-jamming ability of Parallel Combinatory Spread Spectrum system,on the basis of studying the narrowband interference suppression technology in DSSS system,this thesis proposed to suppress the narrowband interference in PCSS system in the way of transform domain filtering.This thesis mainly completed the research content as follows.The PCSS software simulation platform based on MATLAB and mathematical modelings of several common forms of narrowband interference were built.The influence of narrowband interference on the PCSS system was simulated and analyzed.And the necessity of researching on the narrowband interference suppression in PCSS system was proved.The scheme of the narrowband interference suppression in PCSS system based on FFT filtering was given.In order to judge whether the interference suppression is necessary for the system,the SIR strength detection method based on crest factor was proposed,on the basis of research on the traditional SIR strength detection methods.The interference suppression algorithm based on the highest spectral line successive elimination which combined the ideas of SIR strength detection and K-bins interference suppression method was proposed.In order to improve the ability of the system adapted to the change of channelenvironment,several interference suppression algorithms based on adaptive threshold detection were studied,including the DT-FCME algorithm and the Adaptive Multi-threshold algorithm.A new algorithm based on segmented sorting was proposed.At last,the BER performance and implementation complexity of theses interference suppression algorithms were comparative analyzed through computer simulation.