A Gaussian Symbol-Level Model for CDMA Forward Link Intracell Interference

This paper presents a Gaussian approximation for intracell interference on the forward link of a code division multiple access system with fast power control. A probability density function (PDF) is derived for the transmit power variations of each user due to power control adjustments. The PDF is then used to determine the variance of a Gaussian random variable that approximates intracell interference. Simulation demonstrates that this approximation is very accurate even for small spreading factors and low traffic loading levels. The accuracy of the approximation is evaluated for convolutional and turbo coding. The effect of finite power control step sizes and update rates is also investigated.