Routing in highly dynamic wireless networks such as Vehicular Ad-hoc Networks (VANETs) is a challenging task due to frequent topology changes. Sustaining a transmission path between peers in such network environment is difficult. In this thesis, Previous Hop Routing (PHR) is poposed; an opportunistic forwarding protocol exploiting previous hop information and distance to destination to make the forwarding decision on a packet-by-packet basis. It is intended for use in highly dynamic network where the life time of a hop-by-hop path between source and destination nodes is short. Exploiting the broadcast nature of wireless communication avoids the need to copy packets, and enables redundant paths to be formed. To save network resources, especially under high network loads, PHR employs probabilistic forwarding. The forwarding probability is calculated based on the perceived network load as measured by the arrival rate at the network interface. We evaluate PHR in an urban VANET environment using NS2 (for network traffic) and SUMO (for vehicular movement) simulators, with scenarios configured to re ect real-world conditions. The simulation scenarios are configured to use two velocity profiles i.e. Low and high velocity. The results show that the PHR networks able to achieve best performance as measured by Packet Delivery Ratio (PDR) and Drop Burst Length (DBL) compared to conventional routing protocols in high velocity scenarios.

Content Distribution in Vehicular Ad-hoc Networks (VANETs) has always been a critical challenge, due to the peculiar characteristics of VANETs, such as high mobility, intermittent connectivity, and dynamic topologies. In fact, traditional Host-Centric Networks have shown to be unable to handle the increasing demand for content distribution in VANETs. Recently, Information-Centric Networks (ICN) have been proposed to VANETs to cope with the existing issues and improve the content delivery. In Vehicular Information-Centric Networks, instead of communicating in a host-to-host pattern and maintaining host-to-host links during the communication, consumers opportunistically send the Interest requests to the neighbor vehicles, which may have the desired Data packets that can satisfy the Interest packets. However, uncontrolled Interest packet transmissions for content search will result in a waste of resources and diminish the performance of applications in VANETs. In the thesis, we focus on two daunting problems that have limited content distribution in Vehicular Information-Centric Networks when using Vehicle-to-Vehicle (V2V) communication: (i) unreliable content delivery and (ii) broadcast storm. We proposed a suite of protocols, OIFP, LISIC and LOCOS, destined to tackle these and other issues. In the proposed protocols, we have considered different metrics in VANETs that may influence the content distribution, such as distance, velocity, directions and the locations of the producers and consumers. By utilizing a small deferred timer, which is the time holden by the forwarding vehicles before sending the Interest packets out, priority is given to the selected vehicles to forward the Interest packets. Extensive simulations show that all the proposed protocols outperform the vanilla VNDN protocol regarding transmission delay, content satisfaction rate and the average number of Interest transmissions. Besides, we have also implemented several related works and compared with our protocols. The overall performance of the proposed LOCOS protocol outperforms the related works. Moreover, our protocols do alleviate the broadcast storm problem and improve the content delivery rate.

Vehicular Networks (VN) or VANETS has become a cutting-edge topic in the development of innovative solutions for the automotive industry and of special interest to transit management authorities. Well known examples of the potential benefits of enabling communications in vehicles is fostering a better driving by reducing the risk of accidents on the road. Besides the transmission of safety messages among vehicles in the vicinity, the development of non-safety applications will allow the delivery of information services to potential users willing to request them in on-demand basis. To provide such type of services, major challenges need to be tackled to offer secure and reliable communication in anonymous and sometimes hostile communication environments on the roads. These challenges cover security, billing and accounting issues to provide a secure access to services. The objective of this thesis work is to propose a service architecture for on-demand services in vehicular environments. A key point to keep a robust information service supply, stands in the capacity to provide and manage security mechanisms which comprise authentication and authorization of subscribers following a temporary subscription model. These features, along with privacy mechanisms, will offer to the communicating peers a secure way to mutually access and exchange information even if no previous knowledge of each other is available. Policies of service providers can regulate the supply of information services according to the subscribers' profiles. Providers can also define the implementation of accountability models in the form of metering and billing schemes appropriate for VANETS. This will result in the implementation of incentive and collaborative mechanisms to foster service delivery among vehicles.

Vehicular ad hoc networks (VANETs) have attracted much attention over the last few years. VANETs own several significant characteristics, such as the high-rate changing topology led by velocity of vehicles, time-and-location critical safety applications, and Global Positioning System (GPS) devices. In VANETs, as vehicle movement is usually restricted in just bidirectional movements along the roads and streets, geographical location information becomes very useful. In addition, many studies show that position-based routing protocol is a more promising routing strategy for VANETs; therefore security and verification of location information are necessary to be researched. In this thesis, a location verification approach, namely the Cooperative Location Verification (CLV) protocol, is proposed, aiming to prevent position-spoofing attacks on VANETs. The CLV basically uses two vehicles, a Verifier and a Cooperator, to verify the claimed position of a vehicle (Prover), according to two challenge-response procedures. Additionally, the security analysis of the CLV is presented. In order to enhance the CLV by reduce the network overhead, a reputation management system is designed. It utilizes the verification results of the CLV application and maintain every vehicle's reliability in the network. In addition, the solution to sparse networks is briefly discussed. In the simulation, the results show that the proposed CLV performs better than another location verification algorithm, namely the Secure Location Verification (SLV). And the effectiveness of the reputation management system is also demonstrated.

Vehicular ad hoc networks (VANETs) have attracted much attention over the last few years. VANETs own several significant characteristics, such as the high-rate changing topology led by velocity of vehicles, time-and-location critical safety applications, and Global Positioning System (GPS) devices. In VANETs, as vehicle movement is usually restricted in just bidirectional movements along the roads and streets, geographical location information becomes very useful. In addition, many studies show that position-based routing protocol is a more promising routing strategy for VANETs; therefore security and verification of location information are necessary to be researched. In this thesis, a location verification approach, namely the Cooperative Location Verification (CLV) protocol, is proposed, aiming to prevent position-spoofing attacks on VANETs. The CLV basically uses two vehicles, a Verifier and a Cooperator, to verify the claimed position of a vehicle (Prover), according to two challenge-response procedures. Additionally, the security analysis of the CLV is presented. In order to enhance the CLV by reduce the network overhead, a reputation management system is designed. It utilizes the verification results of the CLV application and maintain every vehicle's reliability in the network. In addition, the solution to sparse networks is briefly discussed. In the simulation, the results show that the proposed CLV performs better than another location verification algorithm, namely the Secure Location Verification (SLV). And the effectiveness of the reputation management system is also demonstrated.

Vehicular ad hoc networks (VANETs) have attracted much attention over the last few years. VANETs own several significant characteristics, such as the high-rate changing topology led by velocity of vehicles, time-and-location critical safety applications, and Global Positioning System (GPS) devices. In VANETs, as vehicle movement is usually restricted in just bidirectional movements along the roads and streets, geographical location information becomes very useful. In addition, many studies show that position-based routing protocol is a more promising routing strategy for VANETs; therefore security and verification of location information are necessary to be researched. In this thesis, a location verification approach, namely the Cooperative Location Verification (CLV) protocol, is proposed, aiming to prevent position-spoofing attacks on VANETs. The CLV basically uses two vehicles, a Verifier and a Cooperator, to verify the claimed position of a vehicle (Prover), according to two challenge-response procedures. Additionally, the security analysis of the CLV is presented. In order to enhance the CLV by reduce the network overhead, a reputation management system is designed. It utilizes the verification results of the CLV application and maintain every vehicle's reliability in the network. In addition, the solution to sparse networks is briefly discussed. In the simulation, the results show that the proposed CLV performs better than another location verification algorithm, namely the Secure Location Verification (SLV). And the effectiveness of the reputation management system is also demonstrated.

Vehicular ad hoc networks (VANETs) have attracted much attention over the last few years. VANETs own several significant characteristics, such as the high-rate changing topology led by velocity of vehicles, time-and-location critical safety applications, and Global Positioning System (GPS) devices. In VANETs, as vehicle movement is usually restricted in just bidirectional movements along the roads and streets, geographical location information becomes very useful. In addition, many studies show that position-based routing protocol is a more promising routing strategy for VANETs; therefore security and verification of location information are necessary to be researched. In this thesis, a location verification approach, namely the Cooperative Location Verification (CLV) protocol, is proposed, aiming to prevent position-spoofing attacks on VANETs. The CLV basically uses two vehicles, a Verifier and a Cooperator, to verify the claimed position of a vehicle (Prover), according to two challenge-response procedures. Additionally, the security analysis of the CLV is presented. In order to enhance the CLV by reduce the network overhead, a reputation management system is designed. It utilizes the verification results of the CLV application and maintain every vehicle's reliability in the network. In addition, the solution to sparse networks is briefly discussed. In the simulation, the results show that the proposed CLV performs better than another location verification algorithm, namely the Secure Location Verification (SLV). And the effectiveness of the reputation management system is also demonstrated.

Recent technological advances in wireless communication and the pervasiveness of various wireless communication devices have offered novel and promising solutions to enable vehicles to communicate with each other, establishing a decentralized communication system. An emerging solution in this area is the Vehicular Ad Hoc Networks (VANETs), in which vehicles cooperate in receiving and delivering messages to each other. VANETs can provide a viable alternative in situations where existing infrastructure communication systems become overloaded, fail (due for instance to natural disaster), or inconvenient to use. Nevertheless, the success of VANETs revolves around a number of key elements, an important one of which is the way messages are routed between sources and destinations. Without an effective message routing strategy VANETs' success will continue to be limited. In order for messages to be routed to a destination effectively, the location of the destination must be determined. Since vehicles move in relatively fast and in a random manner, determining the location (hence the optimal message routing path) of (to) the destination vehicle constitutes a major challenge. Recent approaches for tackling this challenge have resulted in a number of Location Service Management Protocols. Though these protocols have demonstrated good potential, they still suffer from a number of impediments, including, signaling volume (particularly in large scale VANETs), inability to deal with network voids and inability to leverage locality for communication between the network nodes. In this thesis, a Region-based Location Service Management Protocol (RLSMP) is proposed. The protocol is a self-organizing framework that uses message aggregation and geographical clustering to minimize the volume of signalling overhead. To the best of my knowledge, RLSMP is the first protocol that uses message aggregation in both updating and querying, and as such it promises scalability, locality awareness, and fault tolerance. Location service management further addresses the issue of routing location updating and querying messages. Updating and querying messages should be exchanged between the network nodes and the location servers with minimum delay. This necessity introduces a persuasive need to support Quality of Service (QoS) routing in VANETs. To mitigate the QoS routing challenge in VANETs, the thesis proposes an Adaptive Message Routing (AMR) protocol that utilizes the network's local topology information in order to find the route with minimum end-to-end delay, while maintaining the required thresholds for connectivity probability and hop count. The QoS routing problem is formulated as a constrained optimization problem for which a genetic algorithm is proposed. The thesis presents experiments to validate the proposed protocol and test its performance under various network conditions.

Recent technological advances in wireless communication and the pervasiveness of various wireless communication devices have offered novel and promising solutions to enable vehicles to communicate with each other, establishing a decentralized communication system. An emerging solution in this area is the Vehicular Ad Hoc Networks (VANETs), in which vehicles cooperate in receiving and delivering messages to each other. VANETs can provide a viable alternative in situations where existing infrastructure communication systems become overloaded, fail (due for instance to natural disaster), or inconvenient to use. Nevertheless, the success of VANETs revolves around a number of key elements, an important one of which is the way messages are routed between sources and destinations. Without an effective message routing strategy VANETs' success will continue to be limited. In order for messages to be routed to a destination effectively, the location of the destination must be determined. Since vehicles move in relatively fast and in a random manner, determining the location (hence the optimal message routing path) of (to) the destination vehicle constitutes a major challenge. Recent approaches for tackling this challenge have resulted in a number of Location Service Management Protocols. Though these protocols have demonstrated good potential, they still suffer from a number of impediments, including, signaling volume (particularly in large scale VANETs), inability to deal with network voids and inability to leverage locality for communication between the network nodes. In this thesis, a Region-based Location Service Management Protocol (RLSMP) is proposed. The protocol is a self-organizing framework that uses message aggregation and geographical clustering to minimize the volume of signalling overhead. To the best of my knowledge, RLSMP is the first protocol that uses message aggregation in both updating and querying, and as such it promises scalability, locality awareness, and fault tolerance. Location service management further addresses the issue of routing location updating and querying messages. Updating and querying messages should be exchanged between the network nodes and the location servers with minimum delay. This necessity introduces a persuasive need to support Quality of Service (QoS) routing in VANETs. To mitigate the QoS routing challenge in VANETs, the thesis proposes an Adaptive Message Routing (AMR) protocol that utilizes the network's local topology information in order to find the route with minimum end-to-end delay, while maintaining the required thresholds for connectivity probability and hop count. The QoS routing problem is formulated as a constrained optimization problem for which a genetic algorithm is proposed. The thesis presents experiments to validate the proposed protocol and test its performance under various network conditions.

Vehicular Ad Hoc Networks (VANETs) are no longer a futuristic promise but rather an attainable technology. Vehicles are already equipped with a variety of computational devices that control or assist drivers in many tasks such as localization, safely breaking, parking and passengers entertainment. The majority of services envisioned for VANETs either require the provision of multimedia support or have it as an extremely beneficial additional feature. In particular, video streaming capabilities over VANETs are crucial to the development of interesting and valuable services. However,VANETs’ highly dynamic topology poses as a demanding challenge to the fulfillment of video streaming’s stringent requirements. The main goal on this thesis is the development of feasible solutions that support the streaming of video content over VANETs. Initially, the main issues of VANETs are explained through both a discussion of its characteristics and the results of some preliminary conclusions. Based on this understanding of VANETs’ peculiarities, three distinguishing solutions are designed REACT-DIS, REDEC and VIRTUS; the two first for video dissemination and the later for video unicast. These solutions offer a great advancement towards the provision of video streaming capabilities but packet loss is still an issue at high data rates. In order to improve the delivery ratios reached by the previous solutions, redundancy is used as an error correction mechanism. The use of redundancy is ideal for VANETs in handling packet loss as they do not require any interaction between source and receivers nodes. Sophisticated coding techniques were used for an efficient use of the increase on entropy of the information sent by the source node. It was also evaluated the selective use of redundancy solely on packets carrying the crucial information of I-frames. Although this selective approach obtained lower overall delivery ratios than when redundancy is used for all packets, the video quality obtained similar improvements under a much lower cost. The evaluation on the use of redundancy has considered the impact on the rate by which unique video content is received at end-users which is fundamental to understand the resolution of videos that can be displayed. This thesis provides several contributions as it advances the knowledge in the peculiarities of VANETs, solutions for video streaming over VANETs and the use of redundancy as an error correction mechanism for video streaming over VANETs.