Applications of suppression filters for CDMA overlay situations

A direct sequence code division multiple access (DS-CDMA) system operating over a Rayleigh fading channel and sharing a common spectrum with various narrowband waveforms is discussed. Because of the presence of these narrowband waveforms, a suppression filter at a receiver is employed to reduce the interference. The average bit error rate (BER) performance is evaluated, and how the performance is influenced by various parameters, such as the number of taps of the suppression filter, the number of multiple-access users, the ratio of the narrowband interference bandwidth to the spread spectrum bandwidth, the interference power-to-signal power ratio, and the ratio of the offset of the interference carrier frequency from the spread spectrum carrier frequency to the half spread spectrum signal bandwidth, is investigated