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Advanced Adaptive Gossiping Using 2-Hop Neighborhood Information

Efficient information dissemination is one of the challenging tasks in most ad-hoc network application domains, be it in wireless sensor networks, mobile ad-hoc networks, or vehicular ad-hoc networks. It is obvious, that flooding has a high communication overhead, leading to channel congestion and packet collisions. Therefore, more efficient dissemination mechanisms were investigated and proposed by the research community. One class of such algorithms is gossiping, where each node forwards a message with a certain probability. The main challenge in gossiping is the proper determination of the forwarding probability, i.e., on the one hand this value has to be chosen high enough to assure a high delivery ratio, on the other hand it has to be as low as possible to reduce communication overhead. At the same time this probability has to be adapted to dynamic network conditions, like changing node density. In this work an advanced scheme for adaptive gossiping is proposed, capable to adjust the dissemination probability dynamically and in a distributed manner. The gossiping probability is determined at a node for every message that has to be forwarded based on two hop neighborhood information. That way, the proposed protocol is capable of working in arbitrary network topologies and densities, enabling more efficient data dissemination compared to existing approaches.

A structure-free aggregation framework for vehicular ad hoc networks

One of the major difficulties for cooperative, decentralized information dissemination in vehicular networks is the heavily varying node density, which can lead to capacity issues of the wireless channel when many vehicles are driving or standing closely together. At the same time, a number of applications do not require exact information from all participating nodes, but higher-level aggregated information. For example, reports on road conditions or on flow of traffic can be aggregated before further dissemination, since remote drivers just need to know a coarse-grained picture of the situation. In this paper, we propose an information aggregation framework using the example of cooperative traffic congestion detection. The difference of our aggregation framework compared to other approaches is that it completely abandons any predefined structures such as grids and any group establishment. First evaluation results show that our approach works well for average speed dissemination on a highway.

Adaptive topology based gossiping in VANETs using position information

Gossiping is a lightweight and simple technique for information dissemination in many application domains, be it in Wireless Sensor Networks (WSNs), Mobile Ad-hoc Networks (MANETs), or Vehicular Ad-hoc Networks (VANETs). Much research has been conducted in the past on probabilistic dissemination methods because of their efficiency compared with simple flooding and their simple application. However most work was focused on static gossiping, i.e., the gossiping probability cannot be adapted according to topology changes. Thus, topology characteristics have to be known in advance. In this work the use of position information for building up a neighborhood relationship is proposed. Based on this information, a forwarding hierarchy is constructed and the protocol is capable to adjust the dissemination probability dynamically in a distributed manner. The protocol is evaluated in a highway scenario, where the network characteristic varies from sparse networks with highly mobile nodes to a traffic jam with very high node density and low node velocities. The applicability of the proposed protocol for such scenarios is shown by simulations.

Dependable and secure geocast in vehicular networks

Inter-vehicular communication envisions many applications to enhance traffic safety. One fundamental communication paradigm used to realize a wide range of such applications is called Geocast, that is, multi-hop broadcast dissemination of messages within a geographically restricted destination region. Because of the safety-related nature of many VANET applications, it is crucial that Geocast protocols ensure dependable dissemination of information. Here, dependability has two aspects. First, a Geocast protocol needs to scale to varying node densities - reliable delivery should be provided both in sparsely connected networks and also in scenarios with high channel load due to high node density. In addition, Geocast needs to be protected against attacks to achieve dependable dissemination of information even in presence of malicious nodes trying to suppress information delivery. In this work, we focus on the goal of Geocast security. We evaluate the impact of several attacks, and, based on these results, we introduce specific countermeasures against the discovered threats. Particularly, we highlight the intrinsic security properties already present in scalability-enhancing mechanisms. Thus, we show how security and scalability complement each other in Geocast protocols. In summary, our focus are lightweight and efficient measures to secure Geocast for usage in VANETs.

Evaluation of Position Based Gossiping for VANETs in an Intersection Scenario

One major issue in vehicular ad-hoc networks (VANETs) is efficient information dissemination. Flooding is widely used in VANETs for this task, but it has severe drawbacks due to the high communication complexity. One class of algorithms to overcome these problems is gossiping, where each node forwards a message with a certain probability. The main challenge in gossiping is the proper determination of an efficient forwarding probability, capable to adapt to dynamic network structures especially in the case of VANETs. The development of such highly adaptive gossiping mechanisms is subject of current research. One recently proposed idea is to combine neighborhood information with position data of vehicles to derive an optimal gossip probability from this information. In this work such a gossip mechanism is extended and evaluated in an intersection area. The applicability of the proposed protocol and its advantage over the existing protocol is shown via simulation.

Linearly Ordered Plugins through Self-Organization

Nowadays, plugin-based applications are quite common. Eclipse is probably the most popular example of such an application. By means of plugins, end-users can add or remove functionality even at runtime. Besides the kernel, plugin-based applications can be kept very small and nearly everything can be designed as a plugin. However, if plugins are added at runtime, their ordering is difficult to organize. This can be observed for graphical user interface representations of plugins, such as menu or list items for example. In particular, the kernel may not refer to a single concrete plugin, since it has to be independent of concrete plugins - according to the plugin concept. Therefore, self-organization is proposed in the present paper as a solution to structure plugin-based applications. A pattern for linearly ordered plugins is presented. The end-user still retains the possibility to reorder the plugins manually according to his preferences. A sample application of the presented pattern in the context of graphical user interfaces is described