Predictor based multiuser and single user detection for time varying frequency selective Rayleigh fading CDMA channels

Multiuser detection for linearly modulated signals (e.g. asynchronous code division multiple access (CDMA)) sent over a time varying, frequency selective Rayleigh fading channel is considered. The multiuser maximum likelihood sequence detector (MLSD) using linear predictors is derived assuming knowledge of the channel second order statistics only. This receiver is appropriate when there are no pilot tones and the channel´s time varying impulse response cannot be accurately estimated. The receiver uses predictors to estimate the received signal and forms a weighted Euclidean distance between the predicted and the received samples. The computational complexity of this receiver grows exponentially with the number of users, hence, we propose an additional single user receiver that is constrained to track and lock to the signal of the desired user, but unlike the conventional single user receiver, it is optimised to take into account the structure of the multiple access interference (MAI). An analysis of the multiuser receiver is also provided. We obtain tight bit error probability bounds using a truncated union bound approach