Placement of WiFi access points for efficient WiFi offloading in an overlay network

In order to alleviate a mobile data explosion problem, WiFi offloading has been proposed. The key issue is how many access points (APs) are needed to accommodate a proper number of users per WiFi AP without severe performance degradation. Although WiFi networks can provide higher throughput as more and more APs are deployed, it may not be a reasonable solution if we consider an increase in the corresponding capital and operational expenditure (CAPEX/OPEX). Therefore, it is important to investigate the minimum required number of WiFi APs which achieve a certain level of performance improvement. In this paper, we focus on the minimum required number of WiFi APs for efficient WiFi offloading. We first set the target average per-user throughput when a WiFi network can play a role as an offloading network of a given cellular network. Based on this criterion, we find the minimum required number of WiFi APs in an overlay network through mathematical analysis.