Estimation of directions of arrival of multipath signals in CDMA systems

In this paper, an algorithm is proposed for estimating the directions of ar rival (DOA's) of multipath signals received from multiple users on the upli nk of a code-division multiple-access system. The correlation matrices of t he received signal before and after code-matched filtering are used to prov ide unique estimates even when the number of required DOA's exceeds the num ber of antenna array elements. This scenario is well known to cause convent ional direction-finding algorithms (such as MUSIC) to fail. Both intersymbo l interference (ISI) and multiple-access interference (MAI) are modeled exa ctly, and so the algorithm performs much better than those which model ISI and MAI as Gaussian noise.