On the performance of chip-interleaved turbo coded DS-CDMA system under impulse noise

In this paper, the performance of turbo coded asynchronous direct-sequence code division multiple access (DS-CDMA) system is evaluated under impulsive noise environment. Two different system models are considered. The first system is one in which message bits are encoded and then spread using a pseudo noise (PN) sequence. The second system is one where the message bits are first spread by a PN sequence and the resultant chip sequence is then chip-by-chip encoded. The output sequences in both cases are chip interleaved to combat the detrimental effects of impulse noise. The results show that the second system model, which is chip-by-chip encoded, gives better error performance for all number of users. This improved performance, however, comes with higher decoding complexity.