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Traffic safety in any type of transportation systems is a global concerned issue. In this paper, we propose a clustering-based multi-channel vehicle-to-vehicle communication system to provide traffic accident avoidance mechanism. In the proposed system, vehicles are self-organized into different clusters, and the traditional single common medium in ad hoc networks has been divided into multiple control...
In vehicular ad hoc networks (VANETs), providing drivers with safety service such as the reliable delivery of an emergency message is a challenge. To propagate the emergency message quickly to all vehicles, the broadcasting technique can be utilized, however, the broadcasting is vulnerable to unreliability. In this paper, we therefore propose a scheme to improve the broadcast reliability by allowing...
This paper proposes a trajectory-based data forwarding (TBD) scheme, tailored for the data forwarding in light- traffic vehicular ad-hoc networks. State-of-the-art schemes have demonstrated the effectiveness of their data forwarding strategies by exploiting known vehicular traffic statistics (e.g., densities and speeds) in these vehicular networks. These results are encouraging, however, further improvements...
Opportunistic networks represent one of the most interesting evolution of MANET paradigm. Generally speaking, opportunistic networks enable user communication in environments where disconnection and reconnection are likely and link performance is extremely non stationary. In this paper, we propose a routing protocol, based on the opportunistic routing paradigm, able to assure connectivity in ad hoc...
The Timeslot Boundary Synchronization Problem occurs when timeslot boundaries become aligned leading to an increase in the probability of message collisions. This alignment, which can occur in Vehicular Ad Hoc Networks using the 802.11p protocols, adversely affects the performance of multi-hop message broadcasts. This paper describes the causes of this phenomenon and describes link and network layer...
In this paper, we study the problem of minimizing the number of data replicas for delay-bounded queries in wireless ad hoc networks. We focus our attention on step-by-step expanding ring search, which provides an upper bound on query delay to any expanding ring based search strategies. We analyze the probabilistic behavior of query delay, and develop an analytical approach to approximate the minimum...
Broadcasting will be extensively used in Vehicular Ad Hoc Networks (VANET), mainly for spreading out safety messages. A number of Intelligent Flooding Schemes (IFSs) have been recently proposed to optimize message dissemination. Some of them exploit a distributed timer-based contention mechanism in order to allow the most suitable nodes to forward the packet and to suppress other potential forwarders...
Modeling movements in office is useful for smart indoor ad hoc networks. People carrying PDA or cell phones can encounter others and in some cases are able to establish connections and transfer data between them. Currently, commonly used mobility models, such as random walk and random waypoint model, do not capture the real movements in real life scenarios, especially in office environments where...
Although the near-far effect has been considered to be the major issue preventing CDMA from being used in ad-hoc networks, in this paper, we show that the near-far effect is not a severe issue in inter-vehicle networks for safety driving support, where packet transmissions are performed in the broadcast manner. Indeed, the near-far effect provides extremely reliable transmissions between near nodes,...
In ad hoc on-demand distance vector (AODV) protocol, once an on-demand link is established, it only maintains that link and does not care about any other paths. AODV may not use some more optimal or reserved paths which occur later but may improve its current transfer. We modify AODV that each node uses routing information provided by the new neighbor nodes to find out and update to better paths and...
In this paper, we study the effect of dense vehicular networks on data dissemination. When using intelligent broadcasting techniques, such as Inter-Vehicle Geocast, we have discovered the spatial broadcast storm problem in which multiple vehicles will be chosen to re-broadcast frames at nearly the same time, resulting in channel contention and collisions. We present a probabilistic version of IVG...
Current work in the area of DTN focuses on various forms of epidemic routing, similar to mathematical epidemiology. In as much as this research has pioneered the field, it has left a large amount of open areas of research. Particularly, the use of group mobility models has limited research, despite its applicability in numerous settings. In this preliminary work, we investigate the design of a group...
Stateless opportunistic forwarding is a simple fault- tolerant distributed approach for data delivery and information querying in wireless ad hoc networks, where packets are forwarded to the next available neighbors in a "random walk" fashion, until they reach the destinations or expire. This approach is robust against ad hoc topology changes and is amenable to computation/bandwidth/energy-constrained...
The most important issue in ad hoc wireless networks is the energy. So there are a lot of research points go to the direction of energy constrained routing protocols in ad hoc wireless network. Where it is very important to examine the routing protocol to make sure it is increase the network life time. This paper introduces a brief overview about the work in this area. Also it proposes a new protocol...
In current multi-hop wireless networks, the routing protocol typically choose the path with the hop count metric. Hop count metric tends to include longer distance link with bad link quality, which then affects the average throughput. In this paper we propose a link-quality aware routing metric for multi-hop wireless networks. This new routing metric simultaneously considers the hop count and the...
The study in this paper investigates the use of (single-hop) cooperative medium access control (MAC) protocols in multi-hop radio networks. The objective is to assess whether the cooperative MAC protocols available in literature can improve performance in multi-hop ad hoc networks. A simulation based comparison is carried out in order to evaluate the potential performance gains and other benefits...
Non-real-time communication is the markedness of vehicular ad hoc networks (VANETs) because of the rapidly changing topology. A delay/disruption tolerant network (DTN) is defined as a dynamic network where the contacts among participants of the network are intermittent or link performances are highly unsteady. In such a periodic and disrupted network, message ferry (MF) is designed to collect and...
Vehicle safety communication applications require safety messages to be received by all the targeted vehicles within their lifetime. We propose a piggybacked cooperative repetition approach for reliably broadcasting safety messages in VANETs. Repetitions by neighbors that receive the original transmission can effectively cover the areas that are missed in the original transmissions. Moreover, the...
In this paper, we efficiently adapt the prominent Ad Hoc On-Demand Distance Vector (AODV) routing protocol with a reactive Local Link Repair, AODV-LR, for effective deployment in restricted power-budget and bandwidth mobile ad hoc sensor networks (MASNET). We introduce a better replacement mechanism to the local repair phase of the AODV. Our new approach is a preemptive, self-repairing AODV (called...
Mobile ad hoc network (MANET) is a collection of mobile nodes that can communicate with each other without using any fixed infrastructure. To support multimedia applications MANETs require an efficient routing protocol and quality of service (QoS) mechanism. Node-Disjoint Multipath Routing Protocol (NDMR) is a practical protocol in MANETs: it reduces routing overhead dramatically and achieves multiple...
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