Combined subcarrier switch off and power loading for 80 MHz bandwidth WLANs

Next generation wireless local area networks, like the upcoming IEEE 802.11ac, strive for large frequency band-widths to cope with the rising traffic demands. Bandwidths of 80 MHz or even 160 MHz are being considered, where a significant frequency diversity among OFDM subcarriers is likely to exist. With a potentially large number of highly attenuated subcarriers it is not clear if the system should better avoid their usage for payload transmission. Such an approach can improve the error performance, however, with every disabled subcarrier the raw data rate is lowered. This trade-off has not been analyzed in the literature despite its significant impact. In this paper we present and evaluate, by means of simulations, schemes that switch off subcarriers and dynamically distribute power on the active ones (while using the same modulation) so as to increase the goodput of an 80 MHz IEEE 802.11 system. We further propose a close-to optimal approach that is light-weight in complexity. If applied on top of realistic channel models the latter outperforms non-adaptive schemes by up to 13 dB and other power loading approaches by more than 5 dB.