Design and analysis of a beacon-less routing protocol for large volume content dissemination in vehicular ad hoc networks

Largevolumecontentdisseminationispursuedbythegrowingnumberofhighquality applications for Vehicular Ad hoc NETworks(VANETs), e.g., the live road surveillance service and the video-based overtaking assistant service. For the highly dynamical vehicular network topology, beacon-less routing protocols have been proven to be efficient in achieving a balance between the system performance and the control overhead. However, to the authors’ best knowledge, the routing design for large volume content has not been well considered in the previous work, which will introduce new challenges, e.g., the enhanced connectivity requirement for a radio link. In this paper, a link Lifetime-aware Beacon-less Routing Protocol (LBRP) is designed for large volume content delivery in VANETs. Each vehicle makes the forwarding decision based on the message header information and its current state, including the speed and position information. A semi-Markov process analytical model is proposed to evaluate the expected delay in constructing one routing path for LBRP. Simulations show that the proposed LBRP scheme outperforms the traditional dissemination protocols in providing a low end-to-end delay. The analytical model is shown to exhibit a good match on the delay estimation with Monte Carlo simulations, as well

Road-based routing in vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) can provide scalable and cost-effective solutions for applications such as traffic safety, dynamic route planning, and context-aware advertisement using short-range wireless communication. To function properly, these applications require efficient routing protocols. However, existing mobile ad hoc network routing and forwarding approaches have limited performance in VANETs. This dissertation shows that routing protocols which account for VANET-specific characteristics in their designs, such as high density and constrained mobility, can provide good performance for a large spectrum of applications. This work proposes a novel class of routing protocols as well as three forwarding optimizations for VANETs. The Road-Based using Vehicular Traffic (RBVT) routing is a novel class of routing protocols for VANETs. RBVT protocols leverage real-time vehicular traffic information to create stable road-based paths consisting of successions of road intersections that have, with high probability, network connectivity among them. Evaluations of RBVT protocols working in conjunction with geographical forwarding show delivery rate increases as much as 40% and delay decreases as much as 85% when compared with existing protocols. Three optimizations are proposed to increase forwarding performance. First, one- hop geographical forwarding is improved using a distributed receiver-based election of next hops, which leads to as much as 3 times higher delivery rates in highly congested networks. Second, theoretical analysis and simulation results demonstrate that the delay in highly congested networks can be reduced by half by switching from traditional FIFO with Taildrop queuing to LIFO with Frontdrop queuing. Third, nodes can determine suitable times to transmit data across RBVT paths or proactively replace routes before they break using analytical models that accurately predict the expected road-based path durations in VANETs

Node Cluster Stability in Vehicular Ad hoc Networks

In recent years, efforts have been made to deploy communication capabilities in vehicles and the transport infrastructure, leading to a potential of vehicular ad hoc networks (VANETs). In the envisioned VANET, communications among vehicles will enhance the intelligent transportation systems (ITS) and support not only public-safety applications, but also a wide range of infotainment applications. Urban roads and highways are highly susceptible to a large number of vehicles and traffic jams. Therefore, the networking protocols for VANETs should be scalable to support such large sized networks. Node clustering (i.e., organizing the network into smaller groups of nodes) is a potential approach to improve the scalability of networking protocols for VANETs. However, high relative vehicle mobility and frequent network topology changes inflict new challenges on maintaining stable clusters. The communication links between network nodes play an essential role in determining the VANET topology. This thesis presents a stochastic microscopic vehicle mobility model to capture the time variations of the distance between two consecutive vehicles on a highway. The proposed mobility model is used to characterize the length and the duration of a communication link connecting two nodes in the network for different vehicular traffic flow conditions. Vehicle trajectory data from real and simulated highways are used for performance evaluation. In a highly dynamic VANET, vehicles join and leave clusters along their travel route, resulting in changes in cluster structure. This thesis investigates the impact of vehicle mobility on node cluster stability. A lumped stochastic model is proposed to describe the temporal variations of a system of intervehicle distances, where each intervehicle distance is represented by the proposed microscopic mobility model. Two metrics are used to measure cluster stability: the time period of invariant cluster-overlap state between two neighboring clusters as a measure of external cluster stability, and the time period of invariant cluster-membership as a measure of internal cluster stability. Using the proposed lumped stochastic model, the two cluster stability metrics are probabilistically characterized for different vehicular traffic flow conditions. Additionally, the limiting behavior of a system of two neighboring clusters is modeled, and the steady-state number of common/unclustered nodes between two clusters is approximately derived. To the best of our knowledge, this is the first mathematical characterization of node cluster stability which takes account of the effect of microscopic vehicle mobility. In addition to the impact of vehicle mobility on node cluster stability, the notion of cluster stability is also related to the network protocol requirements. This thesis explores the effect of cluster characteristics (cluster size and cluster-overlap) on minimizing the generic routing overhead. Furthermore, using the derived cluster stability metrics, the impact of cluster instability on intra- and inter- cluster routing overhead is investigated. The proposed vehicle mobility model is a useful tool for mathematically analyzing the impact of mobility and node density on the performance of network protocols in VANETs. The node cluster stability analysis and the proposed the external and internal cluster stability metrics provide a useful tool for the development of efficient clustering algorithms for VANETs

Probability Detection of A Multi-Hop Communication Link Using Vehicle Mobility Model

ABSTRACT: In a Vehicular Ad-hoc Network (VANET), vehicles communicate with each other and possibly with road-side infrastructure nodes. Node connectivity and the amount of data that can be exchanged are limited by the duration and quality of the communication links established among nodes, which are determined by the space and time dynamics of moving vehicles. We analyze the connectivity dynamics of vehicular ad-hoc networks in a generic signalized urban route. Given the velocity profile of an urban route as a function of space and time, we utilize a fluid model to characterize the general vehicular traffic flow, and a stochastic model to capture the randomness of individual vehicle which is determined by Mesoscopic,and Microscopic mobility model.Mesoscopic is a technique which is used to find time headway between two vehicles and microscopic technique is used to find a distance headway between the two vehicles

Secure multi-constrained QoS reliable routing algorithm for vehicular ad hoc networks (VANETs)

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonVehicular Ad hoc Networks (VANETs) are a particular form of wireless network made by vehicles communicating among themselves and with roadside base stations. A wide range of services has been developed for VANETs ranging from safety to infotainment applications. A key requirement for such services is that they are offered with Quality of Service (QoS) guarantees in terms of service reliability and availability. Furthermore, due to the openness of VANET’s wireless channels to both internal and external attacks, the application of security mechanisms is mandatory to protect the offered QoS guarantees. QoS routing plays an essential role in identifying routes that meet the QoS requirements of the offered service over VANETs. However, searching for feasible routes subject to multiple QoS constraints is in general an NP-hard problem. Moreover, routing reliability needs to be given special attention as communication links frequently break in VANETs. To date, most existing QoS routing algorithms are designed for stable networks without considering the security of the routing process. Therefore, they are not suitable for applications in VANETs. In this thesis, the above issues are addressed firstly by developing a link reliability model based on the topological and mathematical properties of vehicular movements and velocities. Evolving graph theory is then utilised to model the VANET communication graph and integrate the developed link reliability model into it. Based on the resulting extended evolving graph model, the most reliable route in the network is picked. Secondly, the situational awareness model is applied to the developed reliable routing process because picking the most reliable route does not guarantee reliable transmission. Therefore, a situation-aware reliable multipath routing algorithm for VANETs is proposed. Thirdly, the Ant Colony Optimisation (ACO) technique is employed to propose an Ant-based multi-constrained QoS (AMCQ) routing algorithm for VANETs. AMCQ is designed to give significant advantages to the implementation of security mechanisms that are intended to protect the QoS routing process. Finally, a novel set of security procedures is proposed to defend the routing process against external and internal threats. Simulation results demonstrate that high levels of QoS can be still guaranteed by AMCQ even when the security procedures are applied

A Survey on platoon-based vehicular cyber-physical systems

Vehicles on the road with some common interests can cooperatively form a platoon-based driving pattern, in which a vehicle follows another one and maintains a small and nearly constant distance to the preceding vehicle. It has been proved that, compared to driving individually, such a platoon-based driving pattern can significantly improve the road capacity and energy efficiency. Moreover, with the emerging vehicular adhoc network (VANET), the performance of platoon in terms of road capacity, safety and energy efficiency, etc., can be further improved. On the other hand, the physical dynamics of vehicles inside the platoon can also affect the performance of VANET. Such a complex system can be considered as a platoon-based vehicular cyber-physical system (VCPS), which has attracted significant attention recently. In this paper, we present a comprehensive survey on platoon-based VCPS. We first review the related work of platoon-based VCPS. We then introduce two elementary techniques involved in platoon-based VCPS: the vehicular networking architecture and standards, and traffic dynamics, respectively. We further discuss the fundamental issues in platoon-based VCPS, including vehicle platooning/clustering, cooperative adaptive cruise control (CACC), platoon-based vehicular communications, etc., and all of which are characterized by the tight coupled relationship between traffic dynamics and VANET behaviors. Since system verification is critical to VCPS development, we also give an overview of VCPS simulation tools. Finally, we share our view on some open issues that may lead to new research directions