OFDM interference suppression for DS/SS systems using complex FIR filter

In this paper, the performance of narrow band interference (NBI) rejection scheme for direct sequence spread spectrum (DS/SS) is analyzed. A 2-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, the authors place this null at NBI center frequency to mitigate the effect of NBI. In this paper, an OFDM signal is considered as NBI. The performance of this scheme is theoretically analyzed by introducing Queueing model, and validated via simulation.