Fast simulation of OFDM systems over frequency selective fading channels

This paper illustrates the use of the Importance Sampling (IS) technique for efficient simulation of Orthogonal Frequency Division Multiplexing Systems operating over frequency selective fading channels with equalization. In order to achieve higher estimator variance reduction gains, the proper biasing procedure for time domain noise density function and the way of un-biasing the error count at the receiver in frequency domain are shown. Further, the optimum biasing parameters for conventional importance sampling (CIS) and improved importance sampling (IIS) methods are obtained. It is demonstrated, through simulations, that the proposed methods can provide extensive gains in estimator variance reduction and runtime saving compared to the conventional Monte-Carlo (MC) simulations.