The interconnection of vehicles is an important topic concerning the enhancement of

traffic safety and trffic efficiency. Therefore, vehicles exchange position and state information

with each other to establish an awareness level for the calculation of collision

probabilities with their neighbors. To recognize critical safety situations it is essential to

receive information reliably. However, these systems are typically based on wireless ad-hoc

networks that cannot guarantee reliable packet transmission. This is especially the case in

situations where a high number of communication nodes exist.

The aim of this work at hand is the definition of a beaconing algorithm that enables the

establishment of a desired awareness level for critical safety situations especially in high

density traffic scenarios.

First, representative scenarios for collision detection and collision avoidance were specified and metrics for the evaluation of the beaconing algorithms were defined. Based on

these metrics the performance of beaconing algorithms with different static periodical update

rates was evaluated. It is presented that these kinds of beaconing algorithms cannot

provide sfficient results with respect to the required constant information throughput in

high density traffic situations. To provide a high awareness level for each vehicle in its

individual situation in spite of an unreliable communication channel a service-oriented beaconing

approach is dened in this work. It is based on a request/response communication

scheme to compensate particular packet loss. Hereby, a broadcast and a unicast occurrence

of the algorithm are defined accordingly to the corresponding representative scenarios.

It is presented that the service-oriented beaconing approach provides a signicant benefit with respect to the information throughput for low and middle traffic density situations.

However, in high density situations the benefit of this approach is decreasing due to the

increased communication overhead. This is a result of using one single communication

channel. To achieve a high awareness level also in high density trac situations, a signi-

cant modification was defined. Therefore, the usage of multiple communication channels

was introduced to distribute the communication load over several channels. It is specified

to send all service responses on a dedicated service channel to reduce the load on the control

channel where the service requests are transmitted. After an extensive evaluation of

the multi-channel utilization in vehicle ad-hoc networks using IEEE 802.11p it is shown

that the multi-channel version of the service-oriented beaconing approach can achieve significant benefits concerning the information throughput for the collision detection and

collision avoidance scenarios even in high density traffic situations.