Multipath channel estimation for asynchronous random-code-division multiple-access

An estimator for slowly varying multipath channels for each user in a random-code-division multiple-access communications system is constructed and analysed. The estimator requires no training sequence and we compare the performance to the case when such a sequence is available. We show that mean square error in estimation decreases as the inverse of the sample size. It is also shown that the proposed method performs better than other known techniques applied to equivalent fixed-code systems.