Wireless + Transportation: It's More Than Just Cell Phones
Nitin Mangalvedhe (G) tests a prototype of a smart antenna developed in the Mobile & Portable Radio Research Laboratories. The antenna is capable of doing angle of arrival measurements, where the position of a cell phone user is determined by establishing direction of the signal as it arrives at various stations. This type of system would have advantages over satellite-based location systems in areas with tall buildings, tall mountains, or tunnels.
Due to recent advances in wireless telecommunications, the transportation industry is using more wireless technology and is becoming a major focus for communications research and development.
"More and more communications engineers will need to develop an understanding of transportation and public policy issues," said Professor Brian Woerner, associate director of the Department's Mobile & Portable Radio Research Group (MPRG). He cited a wide range of applications for wireless technology, including getting data to and from a vehicle for real-time navigation assistance, accident detection systems, and even vehicle-to-vehicle communication.
"Another big application is the automation of some processes of vehicle control, for safety reasons, or just to pack more cars on the road without expanding roads. For example, in order to auto brake a line of vehicles, or to coordinate response times at intersections, the vehicles will need to be able to communicate with the road and each other. There are a lot of challenges to providing real-time communications for those systems," he said.
"Once you get past navigation and safety issues, a wide range of consumer and industrial applications will also be developed," said Professor Jeff Reed, also an associate MPRG director. "You can imagine services for individuals, such as mobile yellow pages, and for business, such as cargo tracking. With mobile yellow pages, travelers can find out what restaurants are located most conveniently to their position and make dinner reservations. Using cargo tracking, businesses can find out exactly when a shipment arrived at its destination. Other services include providing information about highway interchanges so travelers will know where to exit the Interstate or how many miles they must travel before the next turn. Parents may even be able to track their kids to make sure they arrived home from school safely."
This kind of development will involve teams of engineers and scientists from many disciplines, including electrical and computer engineering, human factors, mechanical engineering, civil engineering, and materials.
"In the past, much of wireless research and development was the design of the radio link," Woerner said, "and we predominantly worked with other electrical engineers. These are becoming increasingly better understood, and the next big developments will be in areas besides the radio link, such as clever ways of linking, and networking together various stations, which starts to bring a real need for cooperation with other disciplines."
Woerner and Reed have been working on transportation applications for several years with teams from the multi-university Intelligent Transportation Systems Center for Excellence and the Virginia Tech Center for Transportation Research (CTR).
One of their current projects is position location technology for cellular and PCS communications. The FCC has mandated that wireless service providers establish E911 service for mobile phone users that can determine the location of the caller within 125 meters for two-thirds of the cases. The same technology is needed by developers of advanced services including navigation and roadside service. "It's a fortuitous instance where both fields have a real need to develop wireless position technology," Woerner commented.
Currently some luxury vehicles offer position location services from the Global Positioning Satellite (GPS) system. However, GPS won't meet all consumer needs, according to Woerner. GPS systems add bulk and cost to a vehicle and do not work where there is no line-of-site position, such as in the shadow of a tall mountain or in cities with tunnels and tall buildings.
Reed and Woerner's team is investigating two different approaches that determine position with respect to cellular base stations. One approach, called time-difference-of-arrival, determines how much delay each signal incurs on the way from a mobile unit back to multiple base stations. The other approach is called the angle-of-arrival method, where the position is determined by establishing direction of the signal as it arrives at various stations.
According to Reed, the primary technical challenges facing the wireless experts will be determining how the surroundings will impact system performance and contending with multipath in the various environments. "Understanding the performance that we can achieve and determining how to deploy such technology is the challenge," he said. "We will need to determine what sort of accuracies can be obtained for different deployment alternatives. This requires mathematical analysis and field experiments."
During the experimental phase, the group plans to run their system on the smart road testbed being built near Tech. "After we've developed our system, we'll be working with researchers in civil and mechanical engineering to integrate and run it. Then there will be a lot of cross-disciplinary work," Reed said.
Woerner described the advantages from working within a cross-functional group like the CTR. "We have a strong expertise in the issues of signal processing and propagation for wireless communications. They have an excellent understanding of the problems of the technical issues and business environment in the transportation community. Working together, we can achieve better integration, and in the end, better systems."