Space-time interference cancellation and turbo equalization of TCM for broadband wireless channels

Broadband transmission which is subject to severe intersymbol interference (ISI) due to multipath fading also suffers from co-channel interference (CCI) due to the presence of adjacent users. The effects of CCI, from one perspective, can be interpreted along with the white channel noise as colored noise at the receiver. The receiver proposed in this paper consists of a broadband beamformer which, in addition to shortening the desired channel impulse response, is designed to whiten the colored noise representing the combined channel noise and CCI. This whitening operation, in some sense, has the effect of removing, or at least reducing, the interference. Cancelling the effects of interfering users and shortening the composite channel impulse response at the beamformer output makes it possible to use a turbo equalizer for the joint equalization and decoding of desired TCM signals.