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51
Broadcast-based directional routing in vehicular ad-hoc networks
- Proceedings of the 9th International Wireless Communications and Mobile Computing Conference, Jul. 1-5, IEEE Xplore Press, Sardinia
, 2012
"... Abstract—An optimized broadcast protocol is proposed for VANETs. It is based on two key information: the direction to the destination and the beamforming angle θ. The efficiency of this technique is demonstrated in terms of packet delivery, bandwidth gain and probability of transmission success. An ..."
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Abstract—An optimized broadcast protocol is proposed for VANETs. It is based on two key information: the direction to the destination and the beamforming angle θ. The efficiency of this technique is demonstrated in terms of packet delivery, bandwidth gain and probability of transmission success. An analytical model is developed to calculate the transmission area. This model allows capturing the propagation shape of the forwarding area. Comparisons with simulations show that the analytical model is precise. Keywords-Broadcast, Vehicular Ad Hoc Networks (VANETs), angle of transmission, area of transmission, bandwidth, proba-bility of success. I.
A Policy Enforcing Mechanism for Trusted Ad Hoc Networks
"... To ensure fair and secure communication in Mobile Ad hoc Networks (MANETs), the applications running in these networks must be regulated by proper communication policies. However, enforcing policies in MANETs is challenging because they lack the infrastructure and trusted entities encountered in tra ..."
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To ensure fair and secure communication in Mobile Ad hoc Networks (MANETs), the applications running in these networks must be regulated by proper communication policies. However, enforcing policies in MANETs is challenging because they lack the infrastructure and trusted entities encountered in traditional distributed systems. This paper presents the design and implementation of a policy enforcing mechanism based on Satem, a kernel-level trusted execution monitor built on top of the Trusted Platform Module. Under this mechanism, each application or protocol has an associated policy. Two instances of an application running on different nodes may engage in communication only if these nodes enforce the same set of policies for both the application and the underlying protocols used by the application. In this way, nodes can form trusted application-centric networks. Before allowing a node to join such a network, Satem verifies its trustworthiness of enforcing the required set of policies. Furthermore, Satem protects the policies and the software enforcing these policies from being tampered with. If any of them is compromised, Satem disconnects the node from the network. We demonstrate the correctness of our solution through security analysis, and its low overhead through performance evaluation of two MANET applications.
VANET Topology Characteristics under Realistic Mobility and Channel Models
- In Proceedings of the 2013 IEEE Wireless Communications and Networking Conference (WCNC
, 2013
"... Abstract—Developing real-time safety and non-safety applica-tions for vehicular ad hoc networks (VANET) requires under-standing the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VAN ..."
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Abstract—Developing real-time safety and non-safety applica-tions for vehicular ad hoc networks (VANET) requires under-standing the dynamics of the network topology characteristics since these dynamics determine both the performance of routing protocols and the feasibility of an application over VANET. Using various key metrics of interest including node degree, number of clusters, link duration and link quality, we provide a realistic analysis of the VANET topology characteristics. In this analysis, we integrate real-world road topology and real-time data extracted from Freeway Performance Measurement System database into the microscopic mobility model in order to generate realistic traffic flows along the highway. Moreover, we use more realistic, recently proposed, obstacle-based channel model and compare the performance of this sophisticated model to the most commonly used more simplistic channel models including unit disc and log-normal shadowing model. Our investigation on the key system metrics reveal that largely used unit disc model fails to realistically model communication channel, while parameters of simplistic models like log normal can be adjusted to match the corresponding system metrics of more complex and hard to implement obstacle based model. I.
14. A TAXONOMY OF DATA COMMUNICATION PROTOCOLS FOR VEHICULAR AD HOC NETWORKS
"... Vehicular Ad Hoc Networks (VANETs) are the potential core of the Intelligent Transportation System (ITS) which aims to increase people safety and improve transportation efficiency. In this paper, we provide the first known taxonomy of VANET data communication protocols, based on road dimension, neig ..."
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Vehicular Ad Hoc Networks (VANETs) are the potential core of the Intelligent Transportation System (ITS) which aims to increase people safety and improve transportation efficiency. In this paper, we provide the first known taxonomy of VANET data communication protocols, based on road dimension, neighbor knowledge, acknowledgment, start of forwarding, competition to retransmit, vehicle connectivity, urgency, and message contents. The taxonomy provides fundamental blocks in VANET data communication protocols and help researchers better understand the details of each protocol. Further, the taxonomy helps in designing new
The dynamics of vehicular networks in urban environments
, 2010
"... Vehicular Ad hoc NETworks (VANETs) have emerged as a platform to support intelligent inter-vehicle communication and improve traffic safety and performance. The road-constrained, high mobility of vehicles, their unbounded power source, and the emergence of roadside wireless infrastructures make VANE ..."
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Vehicular Ad hoc NETworks (VANETs) have emerged as a platform to support intelligent inter-vehicle communication and improve traffic safety and performance. The road-constrained, high mobility of vehicles, their unbounded power source, and the emergence of roadside wireless infrastructures make VANETs a challenging research topic. A key to the development of protocols for inter-vehicle communication and services lies in the knowledge of the topological characteristics of the VANET communication graph. This paper explores the dynamics of VANETs in urban environments and investigates the impact of these findings in the design of VANET routing protocols. Using both real and realistic mobility traces, we study the networking shape of VANETs under different transmission and market penetration ranges. Given that a number of RSUs have to be deployed for disseminating information to vehicles in an urban area, we also study their impact on vehicular connectivity. Through extensive simulations we investigate the performance of VANET routing protocols by exploiting the knowledge of VANET graphs analysis. I.
VANET-enabled Eco-friendly Road Characteristics-aware Routing for Vehicular Traffic”,IEEE
- Vehicular Technology Conference (VTC
, 2013
"... Abstract — The lack of significant breakthroughs in terms of alternative energy sources has caused both fuel consumption and gas emissions to constantly increase. In this context, improving fuel efficiency and reducing emissions in the transportation sector is vital, as vehicles are one of the impor ..."
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Abstract — The lack of significant breakthroughs in terms of alternative energy sources has caused both fuel consumption and gas emissions to constantly increase. In this context, improving fuel efficiency and reducing emissions in the transportation sector is vital, as vehicles are one of the important contributors to air pollution. This paper introduces EcoTrec, a novel eco-friendly routing algorithm for vehicular traffic which considers road characteristics such as surface conditions and gradients, as well as existing traffic conditions to improve the fuel savings of vehicles and reduce gas emissions. EcoTrec makes use of the Vehicular Ad-hoc NETworks (VANET) both for collecting data from distributed vehicles and to disseminate information in aid of the routing algorithm. The algorithm calculates the fuel efficiency of various routes and then directs the vehicle to a fuel efficient route, while also avoiding flash crowding. Simulation-based tests showed that by using EcoTrec, fuel emissions were significantly reduced, when compared with existing state-of-the-art vehicular routing algorithms.
Lifetime Determination for Delay Tolerant Communications in Sparse Vehicular Networks
"... Abstract — Classical ad-hoc network algorithms become impractical for Vehicular Ad Hoc Networks when density of vehicles is low in rural areas and during the periods when the vehicle traffic is low in cities (such as at night). End-to-end connectivity requirement of these algorithms causes deflectio ..."
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Abstract — Classical ad-hoc network algorithms become impractical for Vehicular Ad Hoc Networks when density of vehicles is low in rural areas and during the periods when the vehicle traffic is low in cities (such as at night). End-to-end connectivity requirement of these algorithms causes deflection. Connections get broken when a suitable network element isn’t available for data transfer. This problem which occurs in low dense partially connected Vehicular Ad hoc Networks can be solved by using delay tolerant approaches in routing algorithms. By using the store-carry-forward method, data is carried by network elements until a suitable network element is found. By this way, network connectivity is provided in a delayed manner between momentarily disconnected vehicles. In this paper, the impact of delayed transfer of data to an end-to-end transfer and the impact of data lifetime to the network performance are examined. Considering the speed of vehicles and the desired throughput, lifetime of data is determined according to the network connectivity. The results of this study contribute to the fulfilment of the Quality of Service (QoS) requirements in Vehicular Ad Hoc Network applications. I.
1 Impact of Queuing Discipline on Packet Delivery Latency in Ad Hoc Networks ∗ a
"... Delivering live multimedia streaming over ad hoc networks can improve coordination on battlefields, assist in disaster recovery operations, and help prevent vehicular traffic accidents. However, ad hoc networks often experience congestion faster than wired networks, leading to high end-to-end delays ..."
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Delivering live multimedia streaming over ad hoc networks can improve coordination on battlefields, assist in disaster recovery operations, and help prevent vehicular traffic accidents. However, ad hoc networks often experience congestion faster than wired networks, leading to high end-to-end delays and jitter even for moderate traffic. This paper describes a partial remedy that applies to delay sensitive but loss tolerant applications such as live streaming. We find that under relatively high UDP traffic load, the Last–In–First–Out (LIFO) with Frontdrop queuing discipline achieves less than half the delay of the commonly used First–In–First–Out (FIFO) with Taildrop, while maintaining similar jitter. In low traffic situations, FIFO and LIFO have similar delays, but FIFO with Frontdrop has the lowest jitter. The results can be applied to an adaptive queuing mechanism that changes the queuing discipline at nodes function of the locally observed traffic load. The advantage of such an approach is that it does not require new protocols and does not incur any network overhead.
Context-Aware Fault Tolerance in Migratory Services ABSTRACT
"... Mobile ad hoc networks can be leveraged to provide ubiquitous services capable of acquiring, processing, and sharing real-time information from the physical world. Unlike Internet services, these services have to survive frequent and unpredictable faults such as disconnections, crashes, or users tur ..."
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Mobile ad hoc networks can be leveraged to provide ubiquitous services capable of acquiring, processing, and sharing real-time information from the physical world. Unlike Internet services, these services have to survive frequent and unpredictable faults such as disconnections, crashes, or users turning off their devices. This paper describes a contextaware fault tolerance mechanism for our migratory services model. In this model, a per-client service instance transparently migrates to different nodes in the network to provide a continuous and semantically-correct interaction with its client. The proposed fault tolerance mechanism extends the primary-backup approach with a context-aware checkpointing process. The backup node is dynamically selected based on its distance from the client and service, the similarity of its mobility pattern with those of the client and service, and the state checkpointing frequency and size. We demonstrate the feasibility of our approach through a prototype implementation tested in a small scale ad hoc network of smart phones. Additionally, we simulate our mechanism in a realistic urban environment with 300 pedestrians, cyclists, and cars. Compared to approaches where the backup node is a neighbor of the service node or the client node itself, our mechanism performs as much as 80 % better than the former for recovery ratio, and three times better than the latter for network overhead, while achieving better or similar recovery latency.
MAD: A Dynamically Adjustable Hybrid Locationand Motion-based Routing Protocol for VANETs
"... Abstract—This paper proposes a routing protocol that jointly exploits location and motion information in a dynamically adjusted way, towards self-adaptability in different combinations of mobility and node density conditions. The protocol employs a metric of the rate at which a packet approaches its ..."
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Abstract—This paper proposes a routing protocol that jointly exploits location and motion information in a dynamically adjusted way, towards self-adaptability in different combinations of mobility and node density conditions. The protocol employs a metric of the rate at which a packet approaches its destination over a multihop path, as an effect of both the forwarding to the next hop node and the carry action due to the movement of the receiving node. The metric employs an estimation of the time that a next-hop candidate will retain the message, if selected. This time determines the relative importance of the forwarding and the carry actions. Simulation results demonstrate that the protocol is successful in adapting to a very wide range of mobility and density conditions and compares favorably with other protocols designed for a particular network condition. I.
