Statistical Evaluation of the Error Rate of the Fiberguide Repeater Using Importance Sampling

Abstract

Simulation of repeaters for an optical-fiberguide digital-communication system requires the calculation of the statistical error rate of the signal. The calculations of these error rates are difficult because of the non-gaussian nature of the noise in the optical detector. In this paper, statistical techniques are described which are useful for simulating tails of distributions. In particular, the importance-sampling procedure is used to modify the probability densities of the input values in a way that makes simulation possible. Application of this procedure gives more accurate results in reasonable computer times. The method is applied to the calculation of the error rate of a fiberguide repeater. Realistic examples are simulated. Results compare favorably with experimental measurements. The number of samples needed for simulation was reduced by five to six orders of magnitude. An alternative numerical solution to the problem is also developed.