1. A method to determine bit error rate (BER) for a given channel of a communication system, the method comprising: determining a first statistical representation of at least one deterministic source of noise for the given channel; defining a parametric statistical representation having parameters that model non-deterministic noise for the given channel; estimating values for the parameters of the parametric statistical representation to provide a second statistical representation for the non-deterministic noise based on at least one of measurements or simulations performed for the given channel; and estimating the BER of the given channel as a function of the first and second statistical representations.