Multipath channel estimation for the uplink of a DS-CDMA system

This paper investigates channel estimation in the uplink of a DS-CDMA system. The transmission medium is characterized by the presence of multipath components and the parameters of interest are the delays and complex gains of the propagation paths. We propose a new method for estimating the channel parameters of a user entering the system. The method is based on the maximum likelihood criterion and exploits a training sequence. In comparison with other estimation algorithms it has two advantages. First, it reduces a complicated multidimensional optimization problem to a sequence of one-dimensional problems. Secondly, it has better capability to resolve closely-spaced multipath components. Computer simulations are used to assess its performance. It is found that it is resistant to multiuser interference and can be effectively used in third generation mobile cellular networks.