BER estimation of asynchronous DS/CDMA communications systems

This paper considers the performance of code division multiple access (CDMA) communications. Of particular interest is the evaluation of the average bit error rate (BER) which cannot be performed analytically in most practical situations. Conventional Monte Carlo simulation can provide an alternative performance evaluation tool. Unfortunately, such an approach is often limited by the excessive computational burden. Importance sampling is a modified Monte Carlo technique which can significantly reduce the computational cost required to achieve accurate Monte Carlo estimates. We describe the basic principles behind this method. In particular, we illustrate its use for the efficient simulation of asynchronous direct-sequence (DS) based CDMA systems employing binary phase shift keying modulation along with specific signature sequences for a variety of system parameters.