New results on the performance of MT-DS-SS in the presence of phase noise

Multicarrier (MC) modulation and code-division multiple access (CDMA) schemes have seen much recent attention for the high capacities and flexibility they can provide. A potential difficulty with these systems is their sensitivity to the effects of imperfect orthogonality among subcarriers caused by imperfect frequency up/down conversion due to phase noise. In this work, we provide a general method to upper bound and/or approximate system performance in multitone direct-sequence spread spectrum (MT-DS-SS) signaling in the presence of phase noise, and improve on prior work. We model phase noise as a slow random process with small variance. We assume coherent detection with BPSK modulation and use a phase noise model based upon one for a practical phase-locked loop (PLL). Comparisons between simulations and analysis show excellent agreement, and also show that performance degradation is dominated by the common phase noise, and that the intercarrier interference (ICI) contribution is very small. Our analytical/numerical method is useful for performance evaluation when the target error probability values are of the order of 10^-6 or lower, and can also be easily applied to any multicarrier system with other phase noise models.