“…In particular, for Rayleigh fading channels, the time-variant channel coefficients can be modeled as a zero-mean complex Gaussian process with autocorre lation function in the form of the zeroth-ordcr Bessel function of the first kind (which is a function of the Doppler frequency). If the Doppler frequency were known here, the channel could be modeled by an auto regressive (AR) process, and the optimal channel estimator would be a Kalman filter [105,106]. considers ML estimation of m ultipath channel parameters in asyn chronous DS-CDMA communication systems assuming th at the user whose channel parameters are to be estimated transm its a training sequence.…”