Research And Simulation Of Interference Detection And Suppression In Dsss

Direct sequence spread spectrum(DSSS) communication systems have been widelyused in civilian and military fields, for its good performance in anti-interference,interception and confidentiality. When the interference becomes very strong, DSSS can notperform well only depending on the processing gain. So it is necessary to exployanti-interference algorithms in DSSS.This paper mainly introduces three types of anti-interference algorithms: time domain,transform domain and code-aided interference suppression. In transform domain, weresearch the techniques based on FFT through comparing their advantages anddisadvantages. Then in this article we research a new technique to complete the frequencydomain processing which is called the Detecton and Suppression Technique Based onSpectrum Accumulation and the Distribution of Chi Square. The predefined scaling factoris derived according to the times of accumulation. From theoretical derivation andsimulation, we can find it rubust and has good suppression effect to the NBI. Throughanalysising the performance of the adaptive filter based on LMS, we develop the algoritmof the LMS adaptive filter at the speed of chip in double channel construction to suppressthe interferences in DSSS. And from the simulation, we can find its better performance andharm less to the spread spectrum signal in high Eb/N0than the traditional algorithm.At last, this article presents a study in order to analyze the effect of NBI suppressionon Carrier Phase bias. From the builded model of carrier phase zero value, it shows theeffect of NBI suppression. Both theoretical analysis and simulations illustrate that, linearphase filter has no effect on carrier phase zero value; Nonlinear phase filter has an effect oncarrier phase zero value, which is directly related to the filter weights.