Analysis on Interference Rejection of DS/SS Systems Using a Complex FIR Filter

Yuki SHIMIZU  Yukitoshi SANADA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E89-A   No.11   pp.3026-3031
Publication Date: 2006/11/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e89-a.11.3026
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Wide Band Systems)
spread spectrum,  direct sequence,  narrow band interference,  FIR,  

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In this paper, the performance of narrow band interference (NBI) rejection scheme for direct sequence spread spectrum (DS/SS) is analyzed. A single-tapped complex FIR filter is used for filtering a chip code to suppress NBI. In this system, the spectrum of transmitted signal has a null at an arbitrary frequency. By choosing filter coefficients, we place this null at NBI center frequency to mitigate the effect of NBI. The performance of this scheme is theoretically analyzed and validated by simulation. We also compare the effectiveness against BPSK interference between the chip code filtering and received signal filtering. The results indicate the chip code filtering is effective against single-tone and BPSK interference, and gains better performance than the received signal filtering at certain level of SNR.