No abstract

No abstract

Abstract-For smart traffic scenarios, communication between traffic participants is of high importance. Classical approaches (e.g. for information about congestions) employ a server-based architecture, which raises scalability and privacy concerns. In this paper, we propose OverDrive, a decentralized overlay-based geocast service that is applicable in smart traffic scenarios and not prone to the shortcomings of centralized designs. Information requests for points in geographic space are routed directly via traffic participants until they reach a node in the proximity of that point. In contrast to other approaches, our overlay is specifically tailored towards supporting mobile nodes-vehicles connected via cellular networks-and leverages their speed and direction for optimizing peering decisions and minimizing maintenance overhead. Exhaustive simulations in complex smart traffic scenarios show that OverDrive achieves high delivery ratios even in high mobility environments. At the same time, communication overhead is kept low, making OverDrive suitable for the use with cellular networks.

In the past many proposals for structured peer-topeer protocols have been published. They differ in properties like overlay topology and routing table maintenance. Furthermore, each protocol exhibits various parameters e.g. to adjust the size of the routing table or stabilization intervals, making it difficult to choose an optimal protocol and parameter set for a given scenario (e.g. churn rate, number of nodes). For this purpose, we developed the overlay simulation framework OverSim and implemented six well known structured overlay protocols. In this paper we first compare these protocols among each other. Furthermore, we study several recursive and iterative routing variants and show the effect of routing table redundancy and lookup parallelism on routing latency and bandwidth costs. For each overlay protocol we identify an optimal parameter set for a typical peer-to-peer scenario. Finally, we show how overlay protocols adapt to variations in churn rate and network size. Our results show considerable advantages of the protocols Kademlia and Bamboo, while De Bruijn based protocols reveal a lack of stability under churn.

No abstract