Interference cancellation for a high data rate user in coded CDMA systems

In CDMA systems combining several traffic channels leads to a multi-code (MC) CDMA system offering higher user data rates without increasing the system bandwidth. Due to imperfect spreading sequences, the transmission quality degrades in case of multipath propagation. The additional noise power caused by co-channel interference increases linearly with the number of traffic channels. In this paper, we demonstrate how to reduce this noise by cancelling out the co-channel interference in an iterative way using soft values of the decoded bits. The gain depends on the operating point of the coded system. Simulation results for turbo codes and convolutional codes are close to the results for an AWGN channel