The wireless technology called 802.11 provides the same function as a wired network which works on Ethernet technology. Wi-Fi networks operate in the 2.4 and 5 GHz radio bands, with some products containing both bands (dual band).
Mobile phones, tablet computers, and laptops use Wi-Fi to connect to the internet. Business establishments and public areas also provide a Wi-Fi connection, these are called Wi-Fi hotspots. While some of these places provide Wi-Fi access for free, others charge a fee to connect to their wireless network.
Sharing data links in networks of cars
Wi-Fi is coming to our cars. Ford Motor Co. has been equipping cars with Wi-Fi transmitters since 2010; according to an Agence France-Presse story last year, the company expects that by 2015, 80 percent of the cars it sells in North America will have Wi-Fi built in. The same article cites a host of other manufacturers worldwide that either offer Wi-Fi in some high-end vehicles or belong to standards organizations that are trying to develop recommendations for automotive Wi-Fi.
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. At the ACM SIGACT-SIGOPS Symposium on Principles of Distributed Computing, taking place this month in Portugal, researchers from MIT, Georgetown University and the National University of Singapore (NUS) will present a new algorithm that would allow Wi-Fi-connected cars to share their Internet connections. “In this setting, we’re assuming that Wi-Fi is cheap, but 3G is expensive,” says Alejandro Cornejo, a graduate student in electrical engineering and computer science at MIT and lead author on the paper.
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.
