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C2X communications research makes progress

Posted: 15 Feb 2011     Print Version  Bookmark and Share

Keywords:C2X system  car-to-car and car-to-infrastructure communications 

The Fraunhofer Institute for communication technology systems supports one of the key technology ventures of the automotive and IT industries with the development of a configurable C2X (car-to-car and car-to-infrastructure communications) system that explains the basic structure of future C2X services.

The hardware for Fraunhofer's C2X system is based on a Wi-Fi hub modified for fast-moving objects such as cars. The device also includes a GPS receiver. The device in the car transmits position and sensor data such as speed, acceleration or skidding conditions to a roadside unit (RSU). In turn, the in-car unit receives current data on road conditions ahead, any known accidents ahead, traffic congestions or the speed recommendations for optimum traffic flow.

The system differentiates between three types of messages: First, periodic standardised telegrams transmitted up to ten times per second to the RSU as well as to other cars. These messages include position, driving direction and speed. The roadside units process these data and generate an overall image of the current traffic situation.

The second message type contains event-based information such as accidents in which the transmitting station is involved or which have been detected by the RSU if many vehicles perform emergency brakes at the same time. Traffic congestion is also detected since many cars in one area at the same time signal very low speed. Another relevant event in this category is ESP activation in one or more cars, which suggests slippery roads.

The third category is application messages. This type includes traffic light signals, or traffic information in general. RSUs can also receive and process messages from sources such as traffic management centres.

The configuration of the C2X system is flexible; in addition to the minimum configuration, additional applications and the respective software can be activated. On-going research has yet to establish ways to protect the system from overload situations resulting from simultaneous vehicular or road events. The Fraunhofer experts are currently looking at methods for what they call "context-sensitive message aggregation." The goal is to aggregate multiple messages of the same type and filter them according to their relevance.

Christoph Hammerschmidt
EE Times

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