ECHOS-Enhanced Capacity 802.11 Hotspots

The total number of hotspot users around the world is expected to grow from 9.3 million at the end of 2003 to 30 million by the end of 2004 according to researcher Gartner. Given the explosive growth in hotspot wireless usage, enhancing capacity of 802.11-based hotspot wireless networks is an important problem. In this paper, we make two important contributions. We first present the AP-CST algorithm that dynamically adjusts the Carrier Sense Threshold (CST) in order to allow more flows to coexist in current 802.11 architectures. We then extend the current hotspot engineering paradigm by allowing every cell and AP access to all available channels. These cells are then managed by the RNC-SC algorithm running in a centralized Radio Network Controller. This algorithm assigns mobile stations to appropriate cells/channels and adjusts transmit power values dynamically, thereby exploiting spatial heterogeneity in distribution of users at the hotspots. Through detailed and extensive simulations, we show that the performance of 802.11-based hotspots can be improved by up to 195% per-cell and 70% overall.