Asymmetric signal processing for indoor wireless LANs

The authors propose an asymmetric structure with reduced complexity at the portable. It uses a decision feedback equalizer (DFE) at the base station to equalize data from the portable and a Tomlinson-Harashima precoder with its forward filter (TH-FF) at the base station to pre-equalize transmission to the portable. All the filters are characterized using available information at the base station only. Performance results presented include bit error rates, signal powers and spectral densities for data rates between 10 to 100 Mbits/s and sensitivity to automatic gain control errors. Using custom designed ASIC, the complexity at the base station appears feasible for up to a 20 Mbits/s rate.