Anti-jamming Adaptive Filtering-based Spread Spectrum Communication System

Recently, the Spread Spectrum (SS) technology has been widely applied in the military field as well as in the civil. It is important research task that prove the ability of anti-jamming in Direct Sequence Spread Spectrum (DSSS). The algorithms of interference rejection based on Least Mean Squares (LMS) and Recursive Least Squares (RLS) are studied.Firstly, the theory of spread spectrum technology was introduced, including the basic theory, the characteristics, the categories, application and several realizations of the spread spectrum Communication System. The mathematics model of DSSS, PN code, correlative reception of spread spectrum signal, synchronization and tracking are studied. Secondly, the analysis of performance of anti-jamming in DSSS is present which includes rejection of Additive White Gaussian Noise (AWGN), Narrow Band Interference (NBI), sine wave noise and block noise. NBI suppression technology in DSSS is introduced. Adaptive filtering is an effective means to counteract NBI that can't be restrained in DSSS. Some commonly adaptive filtering algorithms are introduced.Finally, two representative adaptive filtering algorithms are studied: LMS and RLS. Some simulations of interference suppression to the sine wave noise and NBI are studied, using these methods, showing that LMS and RLS algorithms have a good effect on interference suppression in DSSS.