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.

In this paper, the performance of a multicarrier frequency-hopping/binary frequencyshift keying (MC-FH/BFSK) system with jamming is evaluated. The communication channel is assumed to be Rayleigh fading channel. The considered types of jamming are partial band and broadband jamming. A closed-form expression of the average probability of error due to jamming is obtained. It is found that a smart jammer should be present in all subbands of the MC-FH/BFSK system in order to be effective. Also, a performance comparison between MC-FH/BFSK and single carrier FH/BFSK systems is presented. It is found that, the performance of MC-FH/BFSK under jamming is better than the performance of FH/BFSK.

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Abstract:In this paper, the performance of multicarrier direct sequence code division multiple access (MC-DS-CDMA) system equipped with a suppression filter is analyzed. A suppression filter is used in the MC-DS-CDMA receiver for suppressing narrowband interference (NBI) over a Rayleigh fading channel. The NBI is assumed to be multi binary phase shift keying narrow band (BPSK NB) signals which exist in all subcarriers of the MC-CDMA system. The effect of suppression filter coefficients, MC-DS-CDMA system parameters, and the NBI parameters on the performance of the system is studied. The analysis shows that, the suppression filter can improve the MC-CDMA system performance significantly, and then increases the MC-CDMA system capacity. It is shown that, increasing the number of taps to be more than nine taps increases the complexity of the filter and does not add any performance gain to the system. The system with a suppression filter has better performance than the system without a suppression filter at a range of values of the ratio of the offset of the interference carrier frequency existing in a subband to the half spread spectrum bandwidth of this subband, (q), which varies from zero up to a greater value of ( q ) at which using the suppression filter is useless. This value of q at which the system with and without a suppression filter have the same performance depends on the level of the signal to interference power ratio.