Impact of Explicit Channel Sounding Period on the Wi-Fi MU-MIMO Performance

MIMO is a key technology allowing Wi-Fi to achieve high throughput. In Wi-Fi, the performance of MIMO heavily depends on the Explicit Channel Sounding protocol, which introduces a notable overhead. In this paper, the ns-3 Wi-Fi model is extended to take into account MIMO features, including sounding protocol, channel aging, adaptive scheduling, and selection of spatial streams. Using extensive simulations, the influence of sounding period on multi-user MIMO performance is analyzed in different scenarios. The paper shows that in many scenarios, a single quasi-optimal period exists, which provides a throughput just 10% smaller than that of the optimal period found by exhaustive search. Finally, the scenarios where the quasi-optimal period leads to high throughput loss are described and recommendations on sounding period selection are given.