DATE: Monday, September 27, 2010
TIME: 1:30 pm - 2:30 pm
PLACE: Gates 8102

Alberto Lopez Toledo
Telefonica Research Lab, Barcelona, Spain

TITLE: Exploiting WLAN Deployment Density: Fair WLAN Backhaul Aggregation

In urban environments, residential users can potentially see multiple 802.11 APs in range with high quality, usually connected to broadband links. As the speeds of 802.11 WLAN are typically an order of magnitude higher than those of standard broadband connections, one can use a single 802.11 wireless card to aggregate the bandwidth of multiple AP backhauls in range by virtualizing the card and cycling over the APs in a TDMA fashion. Such multi-AP aggregation scheme has been considered as a way of bypassing the backhaul capacity limit. However, current AP aggregation solutions greedily maximize the individual station throughput without taking fairness into account. This can lead to gross unfair throughput distributions, which can discourage user participation and severely limit commercial deployability. Motivated by this problem, I will present THEMIS, a single-radio station that performs multi-AP backhaul aggregation in a fair and distributed way, without requiring modifications to the existing APs. THEMIS is implemented on commodity hardware, evaluated extensively through controlled experimental tests, and validated in a deployment spanning 3 floors of a multistory building. THEMIS is being used in a commercial trial by a major broadband provider to its customers. THEMIS brings one step closer the possibility of using existing WiFi deployments for several commercial settings, ranging from community-based virtual ISPs to efficient 3G-offloading schemes. This work will be presented at the Mobicom 2010 conference.

Alberto Lopez Toledo is a researcher in the Internet Systems and Networking Group at the Telefonica Research Lab in Barcelona, Spain. He also serves as an Adjunct Professor in the Department of Communication and Information Technologies at Universitat Pompeu Fabra (UPF). Alberto received the M.S. degree in Computer Science (with highest honors) from the University of Murcia (UMU), Spain, and the M. Sc. and the Ph.D. degrees in Electrical Engineering from Columbia University, NY.

Alberto's research interests are in the area of networking and distributed systems, content distribution, social networks and wireless communications. Alberto received the Spanish National Academic Excellence Award, the Columbia Edwin Howard Armstrong Memorial Award, and the La Caixa Foundation and Rafael del Pino Foundation fellowships. He is currently a Institució Catalana de Recerca i Estudis Avançats (ICREA) fellow.

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