User Association for Load Balancing and Energy Saving in Enterprise WLANs

Abstract

As the IEEE 802.11 (WiFi) becomes the de-facto global standard for wireless local area network (WLAN), a huge number of WiFi access points (APs) are deployed and the mobile users enjoy almost ubiquitous wireless Internet access. When densely deployed APs covering a certain area are managed by a single organization (say, an enterprise), there can exist multiple candidate APs for serving a user. In this case, the user association (UA), i.e., the selection of serving AP, holds a key role in the network performance. In this paper, we propose an efficient UA scheme for load balancing among APs and energy saving in the enterprise WLAN, considering various techniques for performance improvement, such as multicast transmission, multiuser multiple-input and multiple-output, and AP sleeping, together. We formulate the problem into a multiobjective optimization and get the solution as the UA scheme. We develop a WLAN testbed to demonstrate the practicality and feasibility of the proposed scheme. Moreover, through extensive simulations, we also compare the performance of the proposed scheme with those of some other UA schemes. The simulation results show that the proposed scheme outperforms the other schemes in terms of the total system throughput, the throughput per working AP, the energy efficiency, and the load balancing factor.