A robust method for estimating multipath channel parameters in the uplink of a DS-CDMA system

In this paper, the problem of estimating the multipath channel parameters of a new user entering the uplink of an asynchronous direct sequence-code division multiple access (DS-CDMA) system is addressed. The problem is described via a least squares (LS) cost function, which is non-linear with respect to the time delays and linear with respect to the gains of the multipath channel. This cost function is proved to be approximately decoupled in terms of the path delays, and thus an iterative procedure of one-dimensional searches turns out to be adequate for time delays estimation. The resulting method is computationally efficient and performs well even for a small number of training symbols. Simulation results show that the proposed technique offers a better estimation accuracy compared to existing related methods, and is robust to multiple access interference.