Survey on load-balancing methods in 802.11 infrastructure mode wireless networks for improving quality of service

Traffic load in any 802.11 infrastructure mode network is typically distributed unevenly between access points (APs), creating hotspots. This is due to the inherent nature of wireless area networks (WLANs), where stations are free to associate to any known AP they desire, and the lack of control by the APs themselves. This imbalance creates a condition where affected APs in the network suffer traffic congestion while others are underutilized, leading to stations experiencing lower throughput, longer latency, and operating below the network potential capacity. To alleviate this problem, some form of load balancing is required to redistribute the work load among other available APs in the wireless network. This article presents a survey of the various works done in performing load balancing in an infrastructure mode wireless network and will cover the common methods including admission control, association management, cell breathing, and association control. Updates to the IEEE standards are also presented that support load-balancing efforts. Finally, software-defined networks are investigated to determine the extent of control integration to support managing and load-balancing WLANs. Trends in load-balancing research are also uncovered that indicate how the introduction of new wireless standards influences the amount of research.