Emerging Wireless from Technology Review
Wireless Highway Networked car safety research is hitting the road By Peter Dizikes March April 2006 A few months ago in Michigan a sedan followed by a minivan both rigged out with prototype wireless communications equipment and software swung onto Halsted Road in Farmington Hills The driver of the sedan then slammed on his brakes as if a dog had run in front of his bumper This is the kind of abrupt move that can cause a rear end crash especially when visibility is poor But this particular sedan had a computer in its trunk outfitted with a Global Positioning System receiver and a short range radio The abrupt brake jamming registered on the computer which broadcast a warning and the sedan s GPS location The minivan similarly equipped picked up the warning via special radio frequency calculated that the sedan s location was just ahead of its own and warned the driver sounding a chime and flashing a red light The vehicles were testing Motorola communi! cations technology as part of a corporate and government push to blanket roads with wirelessly broadcast safety information over the next decade saving lives by getting cars computers to talk to each other To be sure communications driven auto safety features have been envisioned for years But Motorola s tests are part of a new wave of projects that are using such technology in actual vehicles on public roads for the first time There are possibilities for information exchange that hitherto were only imagined says James Misener program leader in transportation safety research at the University of California Berkeley One reason for that explosion of possibilities is that late model cars are already loaded with sensors Computers in today s cars track dozens of driving parameters like when antilock braking systems are activated the rate of deceleration and when temperatures near the road surface near freezing This kind of data could help other cars avoid haza! rds and each other if shared in the right ways For exam! ple in Southfield MI the state Department of Transportation has outfitted light poles at intersections with transponders made by Azulstar the wireless networking firm These gadgets can broadcast a traffic light s GPS position and its state red yellow or green Approaching cars equipped with prototype computers can examine this data together with information on speed and location and alert drivers who seem likely to run red lights And as part of the Motorola project transponders housed in small gray boxes have been affixed to light poles along several kilometers of local streets in Farmington Hills The roadside radio units have a range of 1 6 kilometers Vehicles could collaborate with transponders to relay data across long distances to give drivers farther afield advance notice about conditions ranging from bad weather to dangerous road conditions to accidents While 10 states plan to participate in similar tests Michigan says its roads will soon have the largest numbe! r of specially equipped vehicles and roadside transponders Later this year Chrysler will outfit a batch of cars with autonomous communication systems and test them itself in Auburn Hills and Southfield This rash of testing represents a changing approach to auto safety Despite years of incremental efforts to make vehicles safer air bags antilock brakes pretensioning seatbelts the number of annual U S traffic fatalities has remained above 40 000 for a decade partly because the total numbers of vehicles on roadways continues to increase We ve kind of reached the end of the road with passive safety says Steve Speth director of the Vehicle Safety Office at the Chrysler Group Now the emphasis is on using wireless technology to help drivers actively avoid accidents especially at intersections the site of 17 percent of vehicle fatalities Once we start connecting vehicles we will see a reduction in the total number of fatalities says Peter Sweatman dire! ctor of the University of Michigan Transportation Research Ins! titute i n Ann Arbor That really is the future direction of auto safety The Federal Communications Commission has set aside a swath of radio bandwidth strictly for short range communications on the nation s roads It s an essential provision cellular telephone networks do not establish connections fast enough Wireless auto safety still faces roadblocks like questions about carmakers liability if say the technology doesn t prevent a crash But Ford General Motors DaimlerChrysler and Nissan have linked up with the Michigan DOT to perform experiments like Motorola s And they re joining with Toyota BMW and Volkswagen for collision avoidance tests on public roads Some applications could be in cars soon Ford for example plans to start tests in 2007 for possible production by 2011 How an upcoming Motorola test in Michigan will work 1 Transponder beams out GPS location and color of traffic light to nearby cars 2 Red car uses its GPS data and speed to calculate that i! t might run light warns driver 3 Red car sends warning that it might run light roadside unit relays the warning 4 Blue car receives relayed signal warns driver that another car might run the light Municipal Mesh Network Protocols developed at MIT are helping the city of Cambridge to go wireless By Neil Savage February 27 2006 The residents of Cambridge MA may soon be able to log onto the Internet from any bus stop or city park The city is working with MIT to go wireless with a special focus on giving low income residents access to the Internet The project is based on an experimental system called Roofnet an unplanned multiroute mesh network developed at MIT s Computer Science and Artificial Intelligence Laboratory A mesh network is a series of radio transmitters and receivers randomly dispersed over an area To get data from one part of the mesh to another the network must figure out the best route between them which can change depending on network traff! ic data rates and even the weather Roofnet has been operati! ng for a bout three years across an area of roughly four square kilometers near MIT using a few dozen transmitting receiving nodes and one wired Internet connection through MIT The nodes have been located in the homes and offices of volunteers most of them MIT students and staff A node consists of a small box containing a hard drive software written by the researchers and the same kind of radio card used in laptops operating on the Wi Fi standard There s an Ethernet port into which a user can plug his or her laptop and a connection to an antenna Generally an antenna has been attached to a roof with a cable running in a window But that has required flat roofs and users who can get up on the roof to install the antenna Now Roofnet is experimenting with antennas that can be placed in windows they won t get as much coverage since the signal can t pass through the building but they re easier to use The original idea behind Roofnet was to exploit the benefits of a random! unplanned network It s not like making a cell phone network where you have to plan very carefully where the cell towers go says Robert Morris associate professor of computer science at MIT who heads the project With simple to use equipment that requires minimal maintenance the Cambridge wide network could be inexpensive and grow organically The downside is that in some areas where a node is far away from its nearest neighbor the service can be unacceptably poor Cambridge plans to remedy these coverage problems by attaching antennas to as many tall buildings as possible Jerrold Grochow MIT s vice president of information services and technology says the city views the project as a utility like providing electricity for street lights It s not meant to compete with someone in their home buying cable modem or DSL service he says A random mesh of radios works very differently from the wired Internet and Morris s group has had to figure out protocols to g! et the nodes to communicate Like the Internet the network re! lies on transmission control protocol or TCP where data is broken up into packets and both the sender and receiver work to make sure all the packets get through and are put back together in the right order With radio though one has to choose the best among several possible routes between sender and receiver You ve got a huge choice how you route your data through the network Morris says Unfortunately many of those choices are much worse than others Some nodes may get radio interference that drowns out part of the transmission or may drop out entirely for all sorts of reasons For instance transmissions sent on the Wi Fi frequency of 2 4 gigahertz are strongly absorbed by water so the network operates differently in the summer when trees can be covered in rain laden leaves In other cases a passing truck can reflect radio signals and cause interference Nodes may also be so far apart that a signal only gets through intermittently Roofnet tries to work around these! problems Its nodes constantly broadcast status reports that signal where they are and which nearby nodes they re in communication with By tracking these status reports the network can select the best route between any two nodes at a particular moment If a connection drops out in mid transmission the network sends the data along a different route Monitoring the connection between each pair of nodes also allows the network to decide how fast to send the data If the rate of transmission is too low users don t get all the potential out of the network But if it s too high the signal to noise ratio drops and the data can get lost The radios use a brute force approach sending out test signals at all possible rates between one and 54 megabits per second to figure out the highest rate at which data can be trans Wireless Highway Networked car safety research is hitting the road By Peter Dizikes March April 2006 A few months ago in Michigan a sedan followed by a miniv! an both rigged out with prototype wireless communications e! quipment and software swung onto Halsted Road in Farmington Hills The driver of the sedan then slammed on his brakes as if a dog had run in front of his bumper This is the kind of abrupt move that can cause a rear end crash especially when visibility is poor But this particular sedan had a computer in its trunk outfitted with a Global Positioning System receiver and a short range radio The abrupt brake jamming registered on the computer which broadcast a warning and the sedan s GPS location The minivan similarly equipped picked up the warning via special radio frequency calculated that the sedan s location was just ahead of its own and warned the driver sounding a chime and flashing a red light The vehicles were testing Motorola communications technology as part of a corporate and government push to blanket roads with wirelessly broadcast safety information over the next decade saving lives by getting cars computers to talk to each other To be sure communication! s driven auto safety features have been envisioned for years But Motorola s tests are part of a new wave of projects that are using such technology in actual vehicles on public roads for the first time There are possibilities for information exchange that hitherto were only imagined says James Misener program leader in transportation safety research at the University of California Berkeley One reason for that explosion of possibilities is that late model cars are already loaded with sensors Computers in today s cars track dozens of driving parameters like when antilock braking systems are activated the rate of deceleration and when temperatures near the road surface near freezing This kind of data could help other cars avoid hazards and each other if shared in the right ways For example in Southfield MI the state Department of Transportation has outfitted light poles at intersections with transponders made by Azulstar the wireless networking firm ! These gadgets can broadcast a traffic light s GPS position and! its sta te red yellow or green Approaching cars equipped with prototype computers can examine this data together with information on speed and location and alert drivers who seem likely to run red lights And as part of the Motorola project transponders housed in small gray boxes have been affixed to light poles along several kilometers of local streets in Farmington Hills The roadside radio units have a range of 1 6 kilometers Vehicles could collaborate with transponders to relay data across long distances to give drivers farther afield advance notice about conditions ranging from bad weather to dangerous road conditions to accidents While 10 states plan to participate in similar tests Michigan says its roads will soon have the largest number of specially equipped vehicles and roadside transponders Later this year Chrysler will outfit a batch of cars with autonomous communication systems and test them itself in Auburn Hills and Southfield This rash of testing represen! ts a changing approach to auto safety Despite years of incremental efforts to make vehicles safer air bags antilock brakes pretensioning seatbelts the number of annual U S traffic fatalities has remained above 40 000 for a decade partly because the total numbers of vehicles on roadways continues to increase We ve kind of reached the end of the road with passive safety says Steve Speth director of the Vehicle Safety Office at the Chrysler Group Now the emphasis is on using wireless technology to help drivers actively avoid accidents especially at intersections the site of 17 percent of vehicle fatalities Once we start connecting vehicles we will see a reduction in the total number of fatalities says Peter Sweatman director of the University of Michigan Transportation Research Institute in Ann Arbor That really is the future direction of auto safety The Federal Communications Commission has set aside a swath of radio bandwidth strictly for short! range communications on the nation s roads It s an essential! provisi on cellular telephone networks do not establish connections fast enough Wireless auto safety still faces roadblocks like questions about carmakers liability if say the technology doesn t prevent a crash But Ford General Motors DaimlerChrysler and Nissan have linked up with the Michigan DOT to perform experiments like Motorola s And they re joining with Toyota BMW and Volkswagen for collision avoidance tests on public roads Some applications could be in cars soon Ford for example plans to start tests in 2007 for possible production by 2011 How an upcoming Motorola test in Michigan will work 1 Transponder beams out GPS location and color of traffic light to nearby cars 2 Red car uses its GPS data and speed to calculate that it might run light warns driver 3 Red car sends warning that it might run light roadside unit relays the warning 4 Blue car receives relayed signal warns driver that another car might run the light Municipal Mesh Network Protoc! ols developed at MIT are helping the city of Cambridge to go wireless By Neil Savage February 27 2006 The residents of Cambridge MA may soon be able to log onto the Internet from any bus stop or city park The city is working with MIT to go wireless with a special focus on giving low income residents access to the Internet The project is based on an experimental system called Roofnet an unplanned multiroute mesh network developed at MIT s Computer Science and Artificial Intelligence Laboratory A mesh network is a series of radio transmitters and receivers randomly dispersed over an area To get data from one part of the mesh to another the network must figure out the best route between them which can change depending on network traffic data rates and even the weather Roofnet has been operating for about three years across an area of roughly four square kilometers near MIT using a few dozen transmitting receiving nodes and one wired Internet connection through! MIT The nodes have been located in the homes and offices of ! voluntee rs most of them MIT students and staff A node consists of a small box containing a hard drive software written by the researchers and the same kind of radio card used in laptops operating on the Wi Fi standard There s an Ethernet port into which a user can plug his or her laptop and a connection to an antenna Generally an antenna has been attached to a roof with a cable running in a window But that has required flat roofs and users who can get up on the roof to install the antenna Now Roofnet is experimenting with antennas that can be placed in windows they won t get as much coverage since the signal can t pass through the building but they re easier to use The original idea behind Roofnet was to exploit the benefits of a random unplanned network It s not like making a cell phone network where you have to plan very carefully where the cell towers go says Robert Morris associate professor of computer science at MIT who heads the project With simple t! o use equipment that requires minimal maintenance the Cambridge wide network could be inexpensive and grow organically The downside is that in some areas where a node is far away from its nearest neighbor the service can be unacceptably poor Cambridge plans to remedy these coverage problems by attaching antennas to as many tall buildings as possible Jerrold Grochow MIT s vice president of information services and technology says the city views the project as a utility like providing electricity for street lights It s not meant to compete with someone in their home buying cable modem or DSL service he says A random mesh of radios works very differently from the wired Internet and Morris s group has had to figure out protocols to get the nodes to communicate Like the Internet the network relies on transmission control protocol or TCP where data is broken up into packets and both the sender and receiver work to make sure all the packets get through and are p! ut back together in the right order With radio though one h! as to ch oose the best among several possible routes between sender and receiver You ve got a huge choice how you route your data through the network Morris says Unfortunately many of those choices are much worse than others Some nodes may get radio interference that drowns out part of the transmission or may drop out entirely for all sorts of reasons For instance transmissions sent on the Wi Fi frequency of 2 4 gigahertz are strongly absorbed by water so the network operates differently in the summer when trees can be covered in rain laden leaves In other cases a passing truck can reflect radio signals and cause interference Nodes may also be so far apart that a signal only gets through intermittently Roofnet tries to work around these problems Its nodes constantly broadcast status reports that signal where they are and which nearby nodes they re in communication with By tracking these status reports the network can select the best route between any two nodes at! a particular moment If a connection drops out in mid transmission the network sends the data along a different route Monitoring the connection between each pair of nodes also allows the network to decide how fast to send the data If the rate of transmission is too low users don t get all the potential out of the network But if it s too high the signal to noise ratio drops and the data can get lost The radios use a brute force approach sending out test signals at all possible rates between one and 54 megabits per second to figure out the highest rate at which data can be trans
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