SIGNALING PERFORMANCE OVER A PIECE-WISE LINEARLIMITED CHANNEL IN THE PRESENCE OF INTERFERENCE AND GAUSSIAN NOISE

Abstract

Presented here is a model and analysis for evaluating bit error probability of a BPSK signal transmitted through a piece-wise linear (PWL) limited channel subject to a CW interference as well as additive Gaussian noise. The CW interference is assumed to have a random phase Θj over (0, 2π) and a fixed frequency fj which may be either inband or outof- band of the signal channel band. The analysis is carried out in two steps: First an explicit expression for the desired signal, CW tone and their harmonics conditioned on the uplink channel noise if obtained at the output of a PWL limiter. Each of these CW tones and harmonics is modeled into two components--one sinusoid with a mean power and coherently related to Θj and an equivalent Gaussian noise, independent of each other. This equivalent Gaussian noise is also independent of the noise component associated with the desired signal. The interference model is reasonable provided that the frequency fj is not close to the carrier frequency of the signal. Based on the interference model, a conditional error probability expression, whose statistics are constructed through known moment techniques, is formed and averaged over the appropriate random variables. Numerical results for interference model and error rate curves will be compared with those of hardlimited channels in order to illustrate the effect of a PWL limiter.