AutoCast: An Adaptive Data Dissemination Protocol for Traffic Information Systems

Protocols and applications that rely on unicast and multicast communication are well accepted and still gain more and more popularity. However, these communication paradigms are not optimal for a class of wireless applications where communication partners neither establish specific relationships nor need roles like client and server between each other before data exchange. Applications we have in mind deal with up to several thousands of peers as autonomous wireless network nodes. Nodes communicate events like traffic accidents in a local region or information of common interest to a larger group of network nodes. Intermediate nodes forward or rather "gossip" information like in a social communication model, comparable to the news of the big fire of Rome in neronian times travelling through Europe and finally reaching villages in rural areas. The challenge of such a concept is to find efficient local rules, which balance communication with respect to bandwidth usage, latency of data, and data delivery ratio. We introduce the promising application AutoNomos - a decentralized traffic information system - which is well suited for the evaluation of such a data dissemination protocol. Next, we present our new approach called AutoCast that is well optimized and self-adaptable towards various dynamic topologies. We compare AutoCast against the theoretical optimum and existing data dissemination protocols. Finally, simulations will demonstrate the efficiency of the approach.