Performance of a joint Kalman demodulator for multiuser detection

Long code asynchronous CDMA provides a significant challenge, especially when the system is operating at high capacity. We describe a Kalman filter technique that estimates the channel coefficients while demodulating the multiuser signal. A state-space signal model is derived when multiple sources each provide a pilot and numerous user channels, as described by IS95. A numerically efficient algorithm is proposed which estimates each source disjointly but provides interference cancellation through the innovations. A Rayleigh fading model based on Jakes (1974) model is used to describe a time-varying channel. Performance is then demonstrated at high capacity and compared to the conventional detector.