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NS-2, with its IEEE 802.11 support, is a widely utilized simulation tool for wireless communications researchers. However, the current NS-2 distribution code has some significant shortcomings both in the overall architecture and the modeling details of the IEEE 802.11 MAC and PHY modules. This paper presents a completely revised architecture and design for(More)
One key usage of VANET is to support vehicle safety applications. This use case is characterized by the prominence of broadcasts in scaled settings. In this context, we try to answer the following questions: <i>i)</i> what is the probability of reception of a broadcast message by another car depending on its distance to the sender, <i>ii)</i> how to give(More)
—Direct radio-based vehicle-to-vehicle communication can help prevent accidents by providing accurate and up-to-date local status and hazard information to the driver. In this paper, we assume that two types of messages are used for traffic safety-related communication: 1) Periodic messages (" beacons ") that are sent by all vehicles to inform their(More)
We address the challenge of how to share the limited wireless channel capacity for the exchange of safety-related information in a fully deployed vehicular ad hoc network (VANET). In particular, we study the situation that arises when the number of nodes sending periodic safety messages is too high in a specific area. In order to achieve a good performance(More)
— Improving the safety of drivers and passengers by wirelessly exchanging information between vehicles represents a major driving force for the design of vehicular ad hoc networks. In a heavy loaded 802.11-based network, however, safety-related packets might collide frequently and cannot be decoded by a receiver, thus they might not be effective in(More)
Mobile IP, the current IETF proposal for IP mobility support, represents a key element for future <i>All-IP</i> wireless networks to provide service continuity while on the move within a multi-access environment. We conducted a performance evaluation of Mobile IPv6 and its proposed enhancements, i.e., Fast Handovers for Mobile IPv6, Hierarchical Mobile IPv6(More)
In wireless one-hop broadcast communications, each node broadcasts messages to inform all neighbors within an intended communication range. Clearly, the packet transmission of the various nodes might interfere with each other due to the overlapping communication ranges. IEEE 802.11 Distributed Coordination Function (DCF) provides some basic mechanisms for(More)
We conducted a simulative evaluation of the overall performance of Fast Handovers for Mobile IPv6 in comparison with the baseline Mobile IPv6 using the network simulator ns-2 for a 'hot spot' deployment scenario. The simulation scenario comprises four access routers and up to 50 mobile nodes that move randomly and communicate in accordance with the IEEE(More)
The mobility of the nodes in a Mobile Ad-Hoc Network (MANET) is a crucial factor in the performance studies of communication protocols for these kind of networks. For this reason, researchers usually use a randomized node movement model, such as the Random Way-Point Model [6], in the process of designing or analyzing the behavior of their protocols. Since(More)