Multi-user frequency-domain channel identification, interference suppression, and equalization for time-varying broadband wireless communications

In a mobile broadband wireless communication system, an adaptive antenna array can be used to equalize and demodulate multiple users' signals while suppressing interference. In a broadband mobile system operating at 2 GHz or higher, there is a strong potential for severe levels of time and frequency selectivity, which must be accurately tracked for proper multi-user demodulation and interference suppression. We present new frequency-domain techniques that allow for multi-user demodulation even in the presence of high levels of frequency selectivity, and severe time variations across a data block (where a data block is defined to be a group of samples that are FFTd into the frequency domain). These techniques include a time-varying multi-user channel estimation process and a frequency-domain adaptive antenna combining algorithm. The efficacy of the channel estimator and adaptive antenna combining algorithm is demonstrated through simulation results.