Space-time algorithms for multiuser channel estimation in the downlink of UMTS/TDD

We present space-time methods for channel estimation in the downlink of a UMTS/TDD system. The channels associated to all base stations near the mobile receiver are estimated by a multiuser, multi-antenna technique. We develop a minimum mean-square error (MMSE) channel estimator that incorporates midamble detection/estimation and least-squares channel estimation as preparatory stages. Combination of this MMSE channel estimator with a successive interference cancellation scheme allows to cope with strong co-channel interference. Simulation results indicate the good performance of our space-time channel estimator for various realistic propagation scenarios.