Contribution to the design of VANET routing protocols for realistic urban environments

One of the main concerns of the cities' administration is mobility management. In Intelligent Transportation Systems (ITS), pedestrians, vehicles and public transportation systems could share information and react to any situation in the city. The information sensed by vehicles could be useful for other vehicles and for the mobility authorities. Vehicular Ad hoc Networks (VANETs) make possible the communication between vehicles (V2I) and also between vehicles and fixed infrastructure (V2I) managed by the city's authorities. In addition, VANET routing protocols minimize the use of fixed infrastructure since they employ multi-hop V2V communication to reach reporting access points of the city. This thesis aims to contribute in the design of VANET routing protocols to enable reporting services (e.g., vehicular traffic notifications) in urban environments. The first step to achieve this global objective has been the study of components and tools to mimic a realistic VANET scenario. Moreover, we have analyzed the impact of the realism of each one of those components in the simulation results. Then, we have improved the Address Resolution procedure in VANETs by including it in the routing signaling messages. Our approach simplifies the VANET operation and increases the packet delivery ratio as consequence. Afterwards, we have tackled the issue of having duplicate packets in unicast communications and we have proposed routing filters to lower their presence. This way we have been able to increase the available bandwidth and reduce the average packet delay with a slight increase of the packet losses. Besides, we have proposed a Multi-Metric Map aware routing protocol (MMMR) that incorporates four routing metrics (distance, trajectory, vehicle density and available bandwidth) to take the forwarding decisions. With the aim of increasing the number of delivered packets in MMMR, we have developed a Geographical Heuristic Routing (GHR) algorithm. GHR integrates Tabu and Simulated Annealing heuristic optimization techniques to adapt its behavior to the specific scenario characteristics. GHR is generic because it could use any geographical routing protocol to take the forwarding decisions. Additionally, we have designed an easy to implement forwarding strategy based on an extended topology information area of two hops, called 2-hops Geographical Anycast Routing (2hGAR) protocol. Results show that controlled randomness introduced by GHR improves the default operation of MMMR. On the other hand, 2hGAR presents lower delays than GHR and higher packet delivery ratio, especially in high density scenarios. Finally, we have proposed two mixed (integer and linear) optimization models to detect the best positions in the city to locate the Road Side Units (RSUs) which are in charge of gathering all the reporting information generated by vehicles.Una de las principales preocupaciones en la administración de las ciudades es la gestión de la movilidad de sus vehículos, debido a los problemas de tráfico como atascos y accidentes. En los sistemas inteligentes de transporte (SIT), peatones, vehículos y transporte público podrán compartir información y adaptarse a cualquier situación que suceda en la ciudad. La información obtenida por los sensores de los vehículos puede ser útil para otros vehículos y para las autoridades de movilidad. Las redes ad hoc vehiculares (VANETs) hacen posible la comunicación entre los propios vehículos (V2V) y entre vehículos y la infraestructura fija de la red de la ciudad (V2I). Asimismo, los protocolos de encaminamiento para redes vehiculares minimizan el uso de infraestructura fija de red, ya que los protocolos de encaminamiento VANET emplean comunicaciones multisalto entre vehículos para encaminar los mensajes hasta los puntos de acceso de la red en la ciudad. El objetivo de esta tesis doctoral es contribuir en el diseño de protocolos de encaminamiento en redes ad hoc vehiculares para servicios de notificaciones (p.ej. reportes del estado del tráfico) en entornos urbanos. El primer paso para alcanzar este objetivo general ha sido el estudio de componentes y herramientas para simular un escenario realista de red ad hoc vehicular. Además, se ha analizado el impacto del nivel de realismo de cada uno de los componentes de simulación en los resultados obtenidos. Así también, se ha propuesto un mecanismo de resolución de direcciones automático y coherente para redes VANET a través del uso de los propios mensajes de señalización de los protocolos de encaminamiento. Esta mejora simplifica la operación de una red ad hoc vehicular y como consecuencia aumenta la tasa de recepción de paquetes. A continuación, se ha abordado el problema de la aparición inesperada de paquetes de datos duplicados en una comunicación punto a punto. Para ello, se ha propuesto el filtrado de paquetes duplicados a nivel del protocolo de encaminamiento. Esto ha producido un incremento del ancho disponible en el canal y una reducción del retardo medio en la trasmisión de un paquete, a costa de un mínimo aumento de la pérdida de paquetes. Por otra parte, hemos propuesto un protocolo de encaminamiento multi-métrica MMMR (Multi-Metric Map-aware Routing protocol), el cual incorpora cuatro métricas (distancia al destino, trayectoria, densidad de vehículos y ancho de banda) en las decisiones de encaminamiento. Con el objetivo de aumentar la tasa de entrega de paquetes en MMMR, hemos desarrollado un algoritmo heurístico de encaminamiento geográfico denominado GHR (Geographical Heuristic Routing). Esta propuesta integra las técnicas de optimización Tabu y Simulated Annealing, que permiten a GHR adaptarse a las características específicas del escenario. Adicionalmente, hemos propuesto 2hGAR (2-hops Geographical Anycast Routing), un protocolo de encaminamiento anycast que emplea información de la topología de red a dos saltos de distancia para tomar la decisión de encaminamiento de los mensajes. Los resultados muestran que la aleatoriedad controlada de GHR en su operación mejora el rendimiento de MMMR. Asimismo, 2hGAR presenta retardos de paquete menores a los obtenidos por GHR y una mayor tasa de paquetes entregados, especialmente en escenarios con alta densidad de vehículos. Finalmente, se han propuesto dos modelos de optimización mixtos (enteros y lineales) para detectar los mejores lugares de la ciudad donde ubicar los puntos de acceso de la red, los cuales se encargan de recolectar los reportes generados por los vehículos.Postprint (published version

Broadcasting Protocol for Effective Data Dissemination in Vehicular Ad Hoc Networks

VANET topology is very dynamic due to frequent movements of the nodes. Using beacon information connected dominated set are formed and nodes further enhanced with neighbor elimination scheme. With acknowledgement the inter section issues are solve. A modified Broadcast Conquest and Delay De-synchronization mechanism address the broadcasting storm issues. Although data dissemination is possible in all direction, the performance of data dissemination in the opposite direction is investigated and compared against the existing protocols

SNAP : A Software-Defined & Named-Data Oriented Publish-Subscribe Framework for Emerging Wireless Application Systems

The evolution of Cyber-Physical Systems (CPSs) has given rise to an emergent class of CPSs defined by ad-hoc wireless connectivity, mobility, and resource constraints in computation, memory, communications, and battery power. These systems are expected to fulfill essential roles in critical infrastructure sectors. Vehicular Ad-Hoc Network (VANET) and a swarm of Unmanned Aerial Vehicles (UAV swarm) are examples of such systems. The significant utility of these systems, coupled with their economic viability, is a crucial indicator of their anticipated growth in the future. Typically, the tasks assigned to these systems have strict Quality-of-Service (QoS) requirements and require sensing, perception, and analysis of a substantial amount of data. To fulfill these QoS requirements, the system requires network connectivity, data dissemination, and data analysis methods that can operate well within a system\u27s limitations. Traditional Internet protocols and methods for network connectivity and data dissemination are typically designed for well-engineering cyber systems and do not comprehensively support this new breed of emerging systems. The imminent growth of these CPSs presents an opportunity to develop broadly applicable methods that can meet the stated system requirements for a diverse range of systems and integrate these systems with the Internet. These methods could potentially be standardized to achieve interoperability among various systems of the future. This work presents a solution that can fulfill the communication and data dissemination requirements of a broad class of emergent CPSs. The two main contributions of this work are the Application System (APPSYS) system abstraction, and a complementary communications framework called the Software-Defined NAmed-data enabled Publish-Subscribe (SNAP) communication framework. An APPSYS is a new breed of Internet application representing the mobile and resource-constrained CPSs supporting data-intensive and QoS-sensitive safety-critical tasks, referred to as the APPSYS\u27s mission. The functioning of the APPSYS is closely aligned with the needs of the mission. The standard APPSYS architecture is distributed and partitions the system into multiple clusters where each cluster is a hierarchical sub-network. The SNAP communication framework within the APPSYS utilized principles of Information-Centric Networking (ICN) through the publish-subscribe communication paradigm. It further extends the role of brokers within the publish-subscribe paradigm to create a distributed software-defined control plane. The SNAP framework leverages the APPSYS design characteristics to provide flexible and robust communication and dynamic and distributed control-plane decision-making that successfully allows the APPSYS to meet the communication requirements of data-oriented and QoS-sensitive missions. In this work, we present the design, implementation, and performance evaluation of an APPSYS through an exemplar UAV swarm APPSYS. We evaluate the benefits offered by the APPSYS design and the SNAP communication framework in meeting the dynamically changed requirements of a data-intensive and QoS-sensitive Coordinated Search and Tracking (CSAT) mission operating in a UAV swarm APPSYS on the battlefield. Results from the performance evaluation demonstrate that the UAV swarm APPSYS successfully monitors and mitigates network impairment impacting a mission\u27s QoS to support the mission\u27s QoS requirements

Intelligent detection of black hole attacks for secure communication in autonomous and connected vehicles

Detection of Black Hole attacks is one of the most challenging and critical routing security issues in vehicular ad hoc networks (VANETs) and autonomous and connected vehicles (ACVs). Malicious vehicles or nodes may exist in the cyber-physical path on which the data and control packets have to be routed converting a secure and reliable route into a compromised one. However, instead of passing packets to a neighbouring node, malicious nodes bypass them and drop any data packets that could contain emergency alarms. We introduce an intelligent black hole attack detection scheme (IDBA) tailored to ACV. We consider four key parameters in the design of the scheme, namely, Hop Count, Destination Sequence Number, Packet Delivery Ratio (PDR), and End-to-End delay (E2E). We tested the performance of our IDBA against AODV with Black Hole (BAODV), Intrusion Detection System (IdsAODV), and EAODV algorithms. Extensive simulation results show that our IDBA outperforms existing approaches in terms of PDR, E2E, Routing Overhead, Packet Loss Rate, and Throughput

DESIGN OF EFFICIENT IN-NETWORK DATA PROCESSING AND DISSEMINATION FOR VANETS

By providing vehicle-to-vehicle and vehicle-to-infrastructure wireless communications, vehicular ad hoc networks (VANETs), also known as the “networks on wheels”, can greatly enhance traffic safety, traffic efficiency and driving experience for intelligent transportation system (ITS). However, the unique features of VANETs, such as high mobility and uneven distribution of vehicular nodes, impose critical challenges of high efficiency and reliability for the implementation of VANETs. This dissertation is motivated by the great application potentials of VANETs in the design of efficient in-network data processing and dissemination. Considering the significance of message aggregation, data dissemination and data collection, this dissertation research targets at enhancing the traffic safety and traffic efficiency, as well as developing novel commercial applications, based on VANETs, following four aspects: 1) accurate and efficient message aggregation to detect on-road safety relevant events, 2) reliable data dissemination to reliably notify remote vehicles, 3) efficient and reliable spatial data collection from vehicular sensors, and 4) novel promising applications to exploit the commercial potentials of VANETs. Specifically, to enable cooperative detection of safety relevant events on the roads, the structure-less message aggregation (SLMA) scheme is proposed to improve communication efficiency and message accuracy. The scheme of relative position based message dissemination (RPB-MD) is proposed to reliably and efficiently disseminate messages to all intended vehicles in the zone-of-relevance in varying traffic density. Due to numerous vehicular sensor data available based on VANETs, the scheme of compressive sampling based data collection (CS-DC) is proposed to efficiently collect the spatial relevance data in a large scale, especially in the dense traffic. In addition, with novel and efficient solutions proposed for the application specific issues of data dissemination and data collection, several appealing value-added applications for VANETs are developed to exploit the commercial potentials of VANETs, namely general purpose automatic survey (GPAS), VANET-based ambient ad dissemination (VAAD) and VANET based vehicle performance monitoring and analysis (VehicleView). Thus, by improving the efficiency and reliability in in-network data processing and dissemination, including message aggregation, data dissemination and data collection, together with the development of novel promising applications, this dissertation will help push VANETs further to the stage of massive deployment

A comprehensive survey on congestion control techniques and the research challenges on VANET

The nature of vehicular mobility and high speed of vehicular ad hoc network (VANET) with dynamic change in the network topology let the vehicular remain as one of the most challenging problems in vehicular-to-vehicular (V2V) communications. Information dissemination is the major problem in VANET with a fixed bandwidth which is causing congestion on the resources, such as channels and affects the performance of the important application, especially when the emergency or secure transmission of messages is exchanged between the vehicles-to-vehicles communication. To mitigate these problems and introduce a safe vehicular environment in urban and highway, congestion detection and control has been considered and with various strategies and techniques which is take the attention of researchers in VANET. In our survey we mentioned recent techniques and approaches which is used in congestion detection and control and applied different matrices and parameters which is used to evaluate these approaches. In addition, the study also explained the limitation and problems that face the current congestion detection and control schemes, finally we present various solution approach and future expectations in vehicular communication

A holistic framework to improve message delivery in vehicular ad-hoc networks

Vehicular Ad-hoc Networks (VANETs) are wireless communication networks for vehicles that do not require any fixed or central infrastructure. It forms an important part of the intelligent transport system (ITS) which is the convergence of telecommunications, computing and wireless systems with the aim of improving transportation regarding efficiency, safety and management. In addition to the uses of ITS, VANETs will contribute in service access, cooperative driving, entertainment and navigation for cars of the future. Due to the varied use of VANETs, it becomes slightly cumbersome having a "one-fits-all" solution to challenges facing message dissemination in VANETs. While some applications might require a fast and reliable way of disseminating messages amongst members of the network, other applications might be more delay-tolerant without adding extra risks to the dependents of such application. Data dissemination methods are therefore important aspects of VANET that ensure messages are delivered to areas beyond the scope of the originating node. However, several types of research have shown that message propagation for each geographical route is unique to that route, owing to the number of network participants, their speed, and distribution of objects on that route. Many research designs do not consider the vehicles and their traffic characteristics and as such vehicular ad-hoc networks are under-utilised. One of the problems present in the emerging field of vehicular communications is that of optimally disseminating messages within the network to support services such as collision warnings, traffic management, and driverless vehicles amongst others. This problem is a unique research area which involves the entire network and its ability to support the efficient propagation of data. Message dissemination in VANETs could be viewed as routing on much higher macroscopic level, however, the techniques usually applied to data routing on a microscopic level does not utilise available data to efficiently disseminate messages within a vehicular ad-hoc network. Some work done in literature addresses a few constraints at a time; for example a focus on junctions, thereby ignoring vast areas of the wireless network which could have been otherwise used to improve the overall ability to efficiently deliver messages within the road network. For this reason, this thesis investigates the effects of several vehicular factors, how these factors affect the quality of the wireless network on each road, and how this knowledge is advantageous in improving the delivery of messages from a source to its destination within a vehicular ad-hoc network. In proposing a solution that uses otherwise largely ignored road traffic data to improving efficient message delivery, a holistic framework that utilises road traffic information in a unique way is presented. The quality of a wireless network for each road in terms of packets delivered is seen to be influenced by the number of vehicles and their speed which is seen to be unique for each road segment; therefore, allowing the generation of a wireless packet delivery map offline (wireless network map) based on varying number of vehicles and speeds. Current road traffic data can then be compared against the wireless map in order to determine which routes have good network quality and hence the ability to support better message dissemination. This framework is also aimed at helping to fully utilise the VANET bandwidth available by reducing network noise caused by multiple retransmissions of nodes in the network by picking the right path and using only the furthest node on each path. It aims to reduce messages delivery failure, reduce delays in the message delivery where possible and improve the utilisation of vehicles as communication nodes and relays. The Framework for Improving Message Delivery in VANETs (FIMDEV) proposed in this thesis shows the benefit of using the wireless communication database information processed by each vehicle to support message delivery from source to destination within the VANET. Experiments show improved overall packet delivery ratio when compared to standalone routing protocols as FIMDEV uses the wireless network database along with a set of rules for propagating messages within the network

NETCODE: an XOR-based warning dissemination scheme for vehicular wireless networks

The next generation of vehicles will be equipped with automated Accident Warning Systems (AWSs) capable of warning neighbouring vehicles about hazards that might lead to accidents. The key enabling technology for these systems is the Vehicular Ad-hoc Networks (VANET) but the dynamics of such networks make the crucial timely delivery of warning messages challenging. While most previously attempted implementations have used broadcast-based data dissemination schemes, these do not cope well as data traffic load or network density increases. This problem of sending warning messages in a timely manner is addressed by employing a network coding technique in this thesis. The proposed NETwork COded DissEmination (NETCODE) is a VANET-based AWS responsible for generating and sending warnings to the vehicles on the road. NETCODE offers an XOR-based data dissemination scheme that sends multiple warning in a single transmission and therefore, reduces the total number of transmissions required to send the same number of warnings that broadcast schemes send. Hence, it reduces contention and collisions in the network improving the delivery time of the warnings. The first part of this research (Chapters 3 and 4) asserts that in order to build a warning system, it is needful to ascertain the system requirements, information to be exchanged, and protocols best suited for communication between vehicles. Therefore, a study of these factors along with a review of existing proposals identifying their strength and weakness is carried out. Then an analysis of existing broadcast-based warning is conducted which concludes that although this is the most straightforward scheme, loading can result an effective collapse, resulting in unacceptably long transmission delays. The second part of this research (Chapter 5) proposes the NETCODE design, including the main contribution of this thesis, a pair of encoding and decoding algorithms that makes the use of an XOR-based technique to reduce transmission overheads and thus allows warnings to get delivered in time. The final part of this research (Chapters 6--8) evaluates the performance of the proposed scheme as to how it reduces the number of transmissions in the network in response to growing data traffic load and network density and investigates its capacity to detect potential accidents. The evaluations use a custom-built simulator to model real-world scenarios such as city areas, junctions, roundabouts, motorways and so on. The study shows that the reduction in the number of transmissions helps reduce competition in the network significantly and this allows vehicles to deliver warning messages more rapidly to their neighbours. It also examines the relative performance of NETCODE when handling both sudden event-driven and longer-term periodic messages in diverse scenarios under stress caused by increasing numbers of vehicles and transmissions per vehicle. This work confirms the thesis' primary contention that XOR-based network coding provides a potential solution on which a more efficient AWS data dissemination scheme can be built