GeoMapped timing of beacons and unicast messages

In the context of the vehicle-to-vehicle communications system which is currently under ETSI standardization, the periodically broadcast position and status update by each vehicle is a main information source for safety applications. While safety applications require reception of these periodic beacons at high reliability, `hidden-terminal´ packet collisions significantly degrade the range of reliable beacon reception. Furthermore, a vehicular communication system may send unicast messages without RTS/CTS procedure for better scalability, in which case `hidden-terminal´ packet collisions would significantly impair multi-hop deliveries. This paper proposes a timing algorithm for assignment of beacon transmissions. The proposed geographically derived beacon timer solves the problem of `hidden-terminal´ packet collisions, regardless of particular road network topology details. Furthermore, this method does not put any strict synchronization requirement on network layer or MAC layer radio design. As a result, the range of reliable message reception is significantly increased.