In this paper the performance of the DS-CDMA system employing a suppression filter for rejection of narrow band interference (NBI) is provided. Two types of NBI, namely the binary phase shift keying (BPSK) and the single tone interferences, are considered. The behavior of the DS-CDMA system with and without a suppression filter over a
Raleigh fading channel and under the effect of the two types of NBI is analyzed. The effects of suppression filter coefficients, DS-CDMA system parameters, and the NBI parameters on the performance of the system are evaluated analytically. It is shown that the suppression filter is more effective against the single tone NBI than in the case of
the BPSK NBI. Moreover, it is proved that using a suppression filter with total three taps is sufficient to mitigate the effect of either the BPSK or single tone NBI.