Enhancing vehicular internet connectivity using whitespaces, heterogeneity, and a scouting radio

We explore the use of TV whitespace communication systems for providing robust connectivity to vehicles. A key challenge in this setup is the asymmetry in transmit power limits -- the fixed base station is allowed to communicate at up to 4 W, while the mobile gateways in vehicles are limited to 100 mW. This paper presents a specific solution to deal with this asymmetry in which whitespace transceivers are used in the downlink direction while a more traditional cellular path is used in the uplink one. While heterogeneous communication systems have been considered before (e.g., in some satellite networks), our solution explores some unique opportunities that arise in vehicular systems. In particular, we describe a system called Scout that uses a front radio at the head of a vehicle to look ahead and identify the best channel parameters to be used when the rear radio eventually reaches the forward post. We use these channel estimates to adapt a number of transmission mechanisms for improving the performance of flows through this heterogeneous network. We have implemented and deployed this system on moving vehicles in an urban environment, and demonstrated 3 -- 8× performance improvement over simpler alternatives that do not use the scouting technique.