INTERFERENCE CANCELLERS FOR SPREAD SPECTRUM MODULATION BASED MULTIPLE ACCESS SYSTEMS

Systems based on spread spectrum technique are inherently interference resistant. However, asynchronous transmission and multipath propagation causes manifestation of multiuser interference. Multiuser interference in a multiple access system limits the capacity of the system. Hence, it becomes imperative to mitigate the interference. This work presents the design and mathematical analysis of Hybrid Interference Cancellation (HIC) detector for direct-sequence code division multiple access (DS-CDMA). The detector is analysed for single path as well as multipath propagation over a Rayleigh fading channel. Simulation results are compared with the results of Successive Interference Canceller (SIC). Furthermore, the SIC and HIC detectors are tested for convergence. An HIC detector is proposed for MC-CDMA system. The interference canceller discussed in this paper dispenses with the RAKE receiver for diversity combining and data estimation, which averts the likelihood of errors because of incorrect data estimates.