Editing Telematics (section)

=== Wireless vehicle safety communications ===
[[Wireless vehicle safety communications]] telematics aid in car safety and road safety. It is an electronic subsystem in a vehicle used for exchanging safety information about road hazards and the locations and speeds of vehicles over [[short range radio links|short-range radio links]]. This may involve temporary ad hoc wireless local area networks.

Wireless units are often installed in vehicles and fixed locations, such as near traffic signals and emergency call boxes along the road. Sensors in vehicles and at fixed locations, as well as in possible connections to wider networks, provide information [[displayed to the drivers|displayed to drivers]]. The range of the radio links can be extended by forwarding messages along multi-hop paths. Even without fixed units, information about fixed hazards can be maintained by moving vehicles by passing it backwards. It also seems possible for traffic lights, which one can expect to become smarter, to use this information to reduce the chance of collisions.

In the future, it may connect directly to the [[adaptive cruise control]] or other vehicle control aids. Cars and trucks with the wireless system connected to their brakes may move in convoys to save fuel and space on the roads. When a column member slows down, those behind it will automatically slow also. Certain scenarios may required less engineering effort, such as when a radio beacon is connected to a brake light.

In fall 2008, network ideas were tested in Europe, where radio frequency bandwidth had been allocated. The 30&nbsp;MHz allocated is at 5.9&nbsp;GHz, and unallocated bandwidth at 5.4&nbsp;GHz may also be used. The standard is IEEE 802.11p, a low-latency form of the Wi-Fi local area network standard. Similar efforts are underway in Japan and the USA.<ref name="example">"Car Talk", ''IEEE Spectrum'', October 2008, p. 16</ref>