Joint DOA and Channel Parameter Estimation for Code-Division Multiple-Access Systems

We consider the uplink of a DS-CDMA system and we assume that the base station is endowed with a linear antenna array. Transmission takes place over a multipath channel and the goal is to estimate the channel parameters and the directions of arrival of the signals from a user entering the network. Maximum likelihood estimation of all these parameters is not feasible as it involves a search over a multidimensional domain. Through suitable approximations we replace the above search by a sequence of mono-dimensional searches. This results in an estimation algorithm of reasonable complexity for third-generation cellular applications. The performance of the algorithm is assessed by simulation in a scenario inspired by the specifications of the FDD component of the UMTS standard. It is found that the channel parameters and the directions of arrival can be estimated with accuracy close to the Cramer-Rao bound.