Uplink channel estimation in DS/CDMA mobile radio systems with antenna arrays using subspace identification methods

The application of array processing methods in a code division multiple access system with antenna arrays is proposed as a method to improve system performance. Subspaces opthogonality is exploited to estimate the channels with a method similar to the one recently proposed by Moulines et al. (see IEEE Trans. Signal Processing, vo1.43, no.2, 1995). The knowledge of the baseband channels is used in the design of a receiving multi-channel filter that can be seen also as a spatial-temporal combining scheme. The approach is effective also in presence of severe interference among users caused by very short codes or worst case delays and frequency selective multipath propagation.