Scout: an asymmetric vehicular network design over TV whitespaces

Abstract

We explore the use of TV whitespaces based communication systems for providing robust connectivity to vehicles. We envision a setup where whitespaces base stations mounted by roadside that communicate with whitespaces gateway nodes placed on vehicles. A key challenge in this setup is the asymmetry in transmission power limits -- the fixed base station is allowed to communicate at up to 4W, while the mobile gateways on vehicles are limite to 100mW. This paper presents a specific network design called Scout to deal with this asymmetry in which whitespaces transceivers are used in the downlink direction while a more traditional cellular path is used in the uplink one. As the key component of this system, we describe a novel channel probing mechanism that sends a forward radio to look ahead and identify the best channel parameters to be used when the rear radio eventually reaches the forward post. We report various challenges and experience in this design and our on going plans to use it for providing Internet access to public city buses. Our initial results indicate a 4× coverage improvement and 1.4X throughput gain achieved by Scout.