  Apart from mobile cellular networks, IEEE 802.11-based wireless local area
networks (WLANs) represent the most widely deployed wireless networking
technology. With the migration of critical applications onto data networks, and
the emergence of multimedia applications such as digital audio/video and
multimedia games, the success of IEEE 802.11 depends critically on its ability
to provide quality of service (QoS). A lot of research has focused on equipping
IEEE 802.11 WLANs with features to support QoS. In this survey, we provide an
overview of these techniques. We discuss the QoS features incorporated by the
IEEE 802.11 standard at both physical (PHY) and media access control (MAC)
layers, as well as other higher-layer proposals. We also focus on how the new
architectural developments of software-defined networking (SDN) and cloud
networking can be used to facilitate QoS provisioning in IEEE 802.11-based
networks. We conclude this paper by identifying some open research issues for
future consideration.
