A filter bank approach to blind space-time equalization for wideband TDMA

Transmission of multimedia data is the goal of third generation (3G) cellular radio systems necessitating high-speed data links where the multipath delay spread generally encompasses many symbol intervals. A blind multichannel identification scheme is presented along with an attendant space-time equalization algorithm, based on subbanding and the cross-relation method (CRM) of Xu, Liu, Tong, and Kailath (see IEEE Trans. Signal Proc., p.2982-93, 1995). The CRM is applied in each subband, using basis functions derived from the symbol waveform and the bandpass filter, to blindly identify the frequency response of each channel in the given subband. A method is presented for proper phasing of each blind subband channel estimate to reconstruct the full channel impulse response associated with each antenna. A semi-blind approach is presented that follows the blind procedure by a fractionally-spaced decision feedback equalizer where the taps need only span the duration of the original symbol waveform, which in the wideband case is much less than the number of taps needed to span the delay spread as required in a conventional DFE. Simulations are presented using parameters drawn from proposed 3G wideband TDMA standards