Title :
Predictive adaptive loading for HIPERLAN II
Author :
Thoen, Steven ; Van der Perre, Liesbet ; Gyselinckx, Bert ; Engels, Marc ; De Man, Hugo
Author_Institution :
Interuniversitair Microelectron. Center, Leuven, Belgium
Abstract :
Adaptive loading is able to significantly reduce the average symbol error rate (SER) of OFDM-based wireless local networks by exploiting the channel frequency diversity. In time-varying channels however these gains disappear quickly when the channel state feedback rate is limited. We show that by combining ML channel estimation with robust MMSE prediction filters, we can predict the optimal constellation sizes and regain most of the achievable gain of adaptive loading. With only 4 channel measurements spaced one MAC frame apart, the loss compared to the performance of adaptive loading with perfect channel knowledge is limited to 0.7 dB and a gain of 10 dB is achieved over non-adaptive OFDM for an SER=10-6
Keywords :
OFDM modulation; adaptive filters; adaptive systems; diversity reception; error statistics; least mean squares methods; maximum likelihood estimation; prediction theory; smoothing methods; time-varying channels; wireless LAN; HIPERLAN II; MAC frame; ML channel estimation; MMSE prediction filters; OFDM-based wireless local networks; WLAN; average symbol error rate reduction; channel frequency diversity; channel measurements; channel state feedback rate; frequency smoothing filter; optimal constellation size; perfect channel knowledge; predictive adaptive loading; time-varying channels; wireless LAN; Adaptive filters; Channel estimation; Error analysis; Frequency diversity; Gain measurement; Loss measurement; Maximum likelihood estimation; Robustness; State feedback; Time-varying channels;
Conference_Titel :
Vehicular Technology Conference, 2000. IEEE-VTS Fall VTC 2000. 52nd
Conference_Location :
Boston, MA
Print_ISBN :
0-7803-6507-0
DOI :
10.1109/VETECF.2000.883252
