Ford Motor Co. expects that by 2015, 80 percent of the cars it sells in North America will have Wi-Fi built in. Two Wi-Fi-equipped cars sitting at a stoplight could exchange information free of charge, but if they wanted to send that information to the Internet, they’d probably have to use a paid service such as the cell network or a satellite system.
Researchers from MIT, Georgetown University, and the National University of Singapore (NUS) have developed a new algorithm that would allow Wi-Fi-connected cars to share their Internet connections.
The general approach behind the algorithm is to aggregate data from hundreds of cars in just a small handful, which then upload it to the Internet. The problem, of course, is that the layout of a network of cars is constantly changing in unpredictable ways. Ideally, the aggregators would be those cars that come into contact with the largest number of other cars, but they can’t be identified in advance.
The researchers began by considering the case in which every car in a fleet of cars will reliably come into contact with some fraction — say, 1/x — of the rest of the fleet in a fixed period of time. In the researchers’ scheme, when two cars draw within range of each other, only one of them conveys data to the other; the selection of transmitter and receiver is random.
Cars that have already aggregated a lot will start ‘winning’ more and more, and you get this chain reaction. The more people you meet, the more likely it is that people will feed their data to you, according to the researchers. The shift in probabilities is calculated relative to 1/x — the fraction of the fleet that any one car will meet. The smaller the value of x, the smaller the number of cars required to aggregate the data from the rest of the fleet
The advantage of aggregation is that it enables the removal of redundancies in data collected by different sources, so that transmitting the data requires less bandwidth. Although the research focuses on sensor networks, networks of vehicles could partake of those advantages as well.
