  The IEEE 802.11ac standard introduces new downlink multi-user MIMO
(DL-MU-MIMO) transmissions to up to four users in order to increase spatial
reuse in wireless local area networks (WLANs). We argue that even better WLAN
per- formance can be achieved by slightly modifying the DL-MU-MIMO scheduling.
To this end we propose a new queuing mechanism based on the decoupling of EDCA
and DL-MU-MIMO scheduling (DEMS) to avoid head-of-line blocking. We show that
DEMS outperforms traditional 802.11ac scheduling based on first in, first out
transmission queues. The improvement is shown in terms throughput achieved
with: (a) more efficient channel usage, (b) increased probability of
transmission of high priority traffic, and (c) decreased competition between
frames destined to distinct users.

Networking and Internet Architecture