The IEEE is also currently working on an 802.11p draft amendment that would be layered over the IEEE 802.11 standard address — dealing with Wireless Access for the Vehicular Environment (WAVE). It defines enhancements to 802.11 required to support intelligent transportation systems (ITS) applications.
This draft amendment would include data exchange between high-speed vehicles and between the vehicles and the roadside infrastructure. So, for example, trains or buses could signal their approach to upcoming traffic signals, or roadside signs could give real-time traffic reports.
But 802.11p has not yet been released. It is hard to judge what it might mean, and when or how it would achieve critical mass — let alone when 802.11p itself will actually be released.
Some have suggested that to speed implementation of WAVE technologies, the FCC would have to license the 5.9 GHz spectrum for 802.11p applications in the automotive world and the DOT would have to deploy the receivers, transmitters and infrastructure needed to make use of that wireless capability. Although these components individually are inexpensive, retrofitting all the roads and vehicles in even one civic area can add up to a substantial budget item quickly.
Wi-Fi or cellular WAVE apps?
Security and privacy issues would also need to be addressed — as well as whether cellular technologies might beat out Wi-Fi as the technology to carry these features.
According to Karen Hanley, senior director of membership and marketing for the nonprofit Wi-Fi Alliance, one reason cellular technologies are in the running with Wi-Fi for vehicle data transfer is that Wi-Fi transfers you from access point to access point at walking speed, compared to cellular, which moves at about 60 mph.
“Of course,” she adds, “the data transfer is quite different, a trickle versus a fire hose.” That is one of the things the IEEE 802.11p, which is in the testing phase, seeks to address, she says.
The debate over which technologies will reach critical mass for traffic-related uses still rages: some put their money on cellular because many automobiles are already equipped with GPS/cellular transceivers (like GM’s OnStar system) which would give cellular an edge for achieving critical mass in WAVE-type applications.
Others say that as more and more municipalities strive to achieve uninterrupted Wi-Fi access for their other city services, Wi-Fi access would become ubiquitous, which would give Wi-Fi uninterrupted access, compatibility with related services (like police or other emergency services) and a more flexible data stream.
Philadelphia, for example, recently created a mesh Wi-Fi footprint of more than 135 square miles utilizing antennae on streetlights for both the city services network and to provide Wi-Fi access to lower income neighborhoods.
Cities as diverse as Austin, Texas; Lawrence, Kan.; Anaheim, Calif.; Cambridge, Mass.; San Francisco, Calif.; and Champaign-Urbana, Ill., already have partial or complete WiFi mesh coverage.
But regardless of the outcome of emerging Wi-Fi standards and technologies, Wi-Fi — even in its current incarnations — has much to offer.
Wi-Fi is widely implemented in security applications such as surveillance systems (some funded by Homeland Security grants). On-board systems are now available that allow real-time video streaming to nearby police vehicles through Wi-Fi networks, so that responders can execute a response quicker and more effectively.
The Massachusetts Bay Transportation Authority (MBTA), for example, deploys a high-speed wireless mesh network to provide mobile-to-mobile live video feeds between 155 of its new buses and laptops in MBTA police officers’ vehicles.
Of course, IP-based video cameras can run on any connection but once the access points are established, wireless can be more cost-effective and flexible — especially for remote camera locations like the edges of parking lots or out of station tracks.
“We use 802.11b to offload security camera digital video from buses,” says Watanabe. “This is much more efficient. Also the cameras can wirelessly send their operational status so we know if any cameras are not working properly.”
The King County Department of Transportation also uses 802.11b to transfer data from fuel pumps. “It was easier than laying in landlines at the bus base,” Watanabe says.