Application of saddlepoint integration on forward-link analysis of asynchronous cellular DS-CDMA over Rayleigh-faded channels

In this paper, we evaluate the forward-link performance of an asynchronous direct-sequence code-division multiple-access (DS-CDMA) cellular system over a Rayleigh-faded channel using an efficient numerical technique called saddlepoint integration (SPI). As each. mobile receives signals from its own base station as well as other surrounding base stations, the bit-error rate (BER) analysis often results in a complicated, multi-integral expression even though Gaussian approximation is applied. Numerical computation of this expression is limited by the issues of complexity, efficiency and accuracy. As a result, SPI is introduced to evaluate the BER performance efficiently and accurately. The computational effort of this method grows only linearly with the number of interfering cells in the system regardless of the number of active mobiles in the cell. The simplified BER expressions are derived and yield accurate results.