Use of Volterra Filters in OCDMA-based PON to Estimate Beat Noise

Abstract

We propose a scheme for estimating the level of beat noise that adaptively cancels the noise from the received signals and thus solves a critical problem: minimizing the bit error rate of OCDMA systems. This scheme is implemented as an adaptive filter based on an expansion of the Volterra series: the received signal is used to estimate the key components of beat noise, transmitted signal and additive Gaussian noise. The Volterra series can be used to describe the simultaneous occurrence of optical signals from different transmitters, which causes the beat noise. We show the configuration, operation principles and performance of the adaptive filter. We also show that the proposed combination of maximum likelihood detection and the estimation of the beat noise reduces the bit error rate and thus raise the performance of a system so that it approaches the level offered by an equivalent system with no beat noise.