Parallel interference cancellation in multicarrier DS-CDMA systems

Abstract

Abstract-In this paper, we present and analyze the performance of a parallel interference cancellation (PIC) scheme for multicarrier (MC) direct-sequence code-division multiple-access (DS-CDMA) systems. At each cancellation stage in the proposed PIC scheme, on each subcarrier, a weighted sum of the soft outputs of the other users in the current stage is cancelled from the soft output of the desired user (rather than making hard bit decisions of the other users and regenerating and canceling the interfering signals) to form the input to the next stage. At the last stage, the interference cancelled outputs from all the subcarriers are maximal ratio combined (MRC) to form the decision statistic. The scheme has the advantage of not requiring the amplitude estimates of the other users. We derive analytical expressions for the bit error rate (BER) at different stages in the proposed PIC scheme on Rayleigh fading channels. Analytical results are found to agree well with the simulation results. The results show that the proposed PIC scheme offers better interference suppression capability than the conventional matched filter receiver. We also obtain bounds on the coded BER of the proposed PIC scheme for a convolutionally coded multicarrier DS-CDMA system where the PIC-MRC output feeds a soft decision Viterbi decoder.

CrossZig: Combating Cross-Technology Interference in Low-Power Wireless Networks

“…Further physical layer solutions, such as Interference Cancellation, have been considered to combat interference [7], [34], [35]. Here the receiver, with minimal or no coordination from sender, attempts to recover the signal of interest from interference.…”