Performance of a subspace based semi-blind technique in the UMTS TDD mode context

We study the performance of a semi-blind subspace channel estimate in the particular context of the uplink of the UMTS time division duplexing (TDD) mode. The TDD mode of the third generation system UMTS is a multiuser DS-CDMA scheme of maximal spreading factor N=16. In the uplink, each slot corresponds to 2560 chips and the channel estimation is classically achieved by using a 512 training chips midamble. In this well defined context, we study the improvements (in terms of bit error rate) provided by a semi-blind channel estimation technique introduced in the context of the single user system of Gorokhov and Loubaton (see Proc. ICASSP, p.3905-3908, 1997) and studied in detail by Buchoux, Moulines, Cappe and Gorokhov (see SPAWC, 1999)