Research Of Narrowband Interference Suppression And Synchronization In Direct Sequence Spread Spectrum System

In order to improve the security of communication in the circumstances of strong interference, spread spectrum communication have become a strong measure of communication. Spread spectrum communication is noticeable particularly because of its strong anti-jamming,anti-noise,anti-multipath interference,low density of power spectrum,multiple access,high precision measurement and so on, so it has been rapidly studied and widely regarded by international academe since 1980s.The best advantage is its outstanding ability to anti-jam if the processing gain is large enough. However, its ability of interference suppression is always limited. The system performance is dramatically degraded and its capacity is largely reduced if the processing gain is not sufficiently large and no other methods can be adopted to suppress strong interference. Therefore, the suppression techniques to narrowband interference are very mature in DSSS systems.Some interference suppression techniques involved adaptive filtering in the time domain and transform domain processing are discussed in this paper. Among the transform processing, the real-time discrete Fourier transform algorithm is not sensitive to the frequency, power and number of interference, so it could be used to handle fixed and variable multiple interference. The existing techniques have the question that the detection of narrow-band interference position is not precision.