  The new IEEE 802.11 standard, IEEE 802.11ax, has the challenging goal of
serving more users compared to its predecessor IEEE 802.11ac, enabling
consistent and reliable streams of data (average throughput) per station. In
this paper we explore some of the IEEE 802.11ax new mechanisms and compare
between the upper bounds on the throughputs of the Downlink unidirectional UDP
Multi Users (MU) triadic based on Multiple-Input-Multiple-Output (MU-MIMO) and
Orthogonal Frequency Division Multiple Access (OFDMA) transmission multiplexing
format in IEEE 802.11ax vs. IEEE 802.11ac in the Single User (SU) and MU modes
for 1, 4, 8, 16, 32 and 64 stations scenario in reliable and unreliable
channels. The comparison is made as a function of the Modulation and Coding
Schemes (MCS) in use. In IEEE 802.11ax we consider two flavors of
acknowledgment operation settings where the maximum acknowledgment windows are
64 or 256 respectively. In SU scenario IEEE 802.11ax upper bounds on the
throughputs outperform IEEE 802.11ac by about 52% and 74% in reliable and
unreliable channels respectively. In MU-MIMO scenario IEEE 802.11ax upper
bounds on the throughputs outperform IEEE 802.11ac by about 59% and 103% in
reliable and unreliable channels respectively. Also, as the number of stations
increases, the advantage of IEEE 802.11ax in terms of the access delay also
increases.
