Research On Suppressing Narrowband Interference With Adaptive Filtering Techniques In DSSS

Spread Spectrum technology is one of the most widely used technologies of interference rejection,and Direct Sequence Spread Spectrum(DSSS)technology is a kind of applied most widely Spread Spectrum technology.DSSS has strong ability to reject narrow-band interference(NBI)and suppress multiple access interference or decline,but it is also limited by the interference tolerance.If the interference power exceed the tolerance,the anti-interference performance of the system will be lower,so this thesis further studies suppressing narrow-band interference performance in DSSS.Adaptive filtering technology has very nice learning and tracking ability,it can effectively track and suppress narrow-band interference.It can effectively improve the system’s narrow-band interference resistance ability by joining the adaptive filter in the DSSS.In the thesis,the application of adaptive filter is the technology of time-domain linear prediction,by using different adaptive algorithm,including classical least-mean-square(LMS)algorithm and the improved variable step size algorithm.Have done a lot of software simulation about suppressing NBI by adaptive filter with all kinds of algorithm in DSSS,through the analysis,it is found that adaptive filter can improve the narrow-band interference resistance performance of DSSS.