Härri, Jérôme

Kloiber, Bernhard

Strang, Thomas

English

Institute of Transport Research:Publications

Tweaking Vehicular Safety Communications Bernhard Kloiber German Aerospace Center (DLR) Institute of Communications and Navigation Tel.: +49 8153 28-3208 Email: bernhard.kloiber@dlr.de Periodic CAM broadcasts in combination with slow relative speeds can cause recurring hidden terminal packet collisions! IEEE 802.11 OCB* communication enables mutual awareness. Highly dense and complex traffic scenarios. High amount of collisions due to short contention window in IEEE 802.11 OCB! Random Transmit Power Control (RTPC):  Random selection of current TX power for each transmission and vehicle. Motivation Problems Concepts Geo-Backoff: Vehicles with slightly different positions would result in the selection of a significantly different backoff counter (≈ cryptographic hash functions). Results Reducing traffic fatalities Higher TX efficiency in space significantly reduces total packet collisions … … as well as recurring ones due to randomized collision and interference areas! Gained congestion reduction can be used to further increase the TX rate, … … which increases the communication performance significantly for close-by vehicles, where it is critical! Objective: Reduced packet collision probability with close-by vehicles! Investigations still ongoing within the GLOVE project. Requirement  NOT fulfilled! CAM = Cooperative Awareness Message *Outside the Context of a BSS, formerly known as IEEE 802.11p Bernhard Kloiber (DLR), Jérôme Härri (EURECOM), Thomas Strang (DLR) Source: Destatis 2012 Source: Wikimedia Commons 

Tweaking Vehicular Safety Communications

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Institute of Transport Research:Publications