A steady state decoupled Kalman filter technique for multiuser detection

In this paper, we describe a Kalman filter based technique for multiuser detection of asynchronous CDMA systems. Similar to previously proposed techniques, we use a decoupled form of the Kalman filter, which processes each user independently. We then make the further simplifying assumption that the channel statistics are constant over a single symbol allowing us to reduce the Kalman gain to a constant dependent on the current signal to interference plus noise ratio. We study the performance of the constant gain filter and show that by appropriate choice of the gain you can optimize for either minimum bit error rate or maximum interference reduction.