Research On Methods Of Signal-to-Jamming Ratio Strength Detection And Narrow Band Interference Suppression In DSSS

Direct Sequence Spread Spectrum system is widely applied in the military electroniccounter and civilian wireless communication field because of it strong electromagnetic stealthcommunication ability and radio channel adaptability. Although DSSS has strong interferencesuppression ability, when spread spectrum gain and the power is limited, or strongelectromagnetic interference exists in the radio channel, the performance of DSSS will beaffected and even cause a communication link to collapse. Among them, the influence ofnarrowband Interference to DSSS is particularly serious. Therefore, NBI suppression methodsbecome the hot questions and key technical problems which need to solve in the field ofDSSS.This paper is researching on NBI suppression in DSSS. Main contents are as follows:Firstly, DSSS system mathematical model and MATLAB simulation platform is built. Inorder to testify the necessity of adding narrow-band strength detection and suppression inDSSS communication system, this paper simulate the performance of DSSS based on toneinterference, digital NBI and AR interference in the channel.Secondly, Iterative Segmentation Double Threshold Forward Consecutive MeanExcision algorithm based on uniform quantization is introduced to solve the problem of longiteration time in Double Threshold Forward Consecutive Mean Excision algorithm. Thisalgorithm can reduce iteration time and the hardware processing resources demands, improvethe time valid of NBI suppression in DSSS.Thirdly, this paper proposes two algorithms: bandwidth and frame recognition, forsolving the disorder arrangement and uncertain symbols caused by suppressing the multipleinterferences using fast independent component analysis algorithm in DSSS systems.Finally, Detection of signal-to-jamming radio strength algorithm is introduce to solve theproblems of DSSS signal distortions caused by interference suppression device when there isno interference or low interference, and different strength interference correspondedappropriate NBI suppressor. This algorithm calculate the power spectrum flat coefficient ofthe received signal, select the suitable threshold parameters, judge the power of interferencein DSSS system, determine the interference suppressor open or not and switch differentinterference suppressor.