Performance evaluation of a hybrid sensor and vehicular network to improve road safety

In the last years, wireless networks have become a widely spread type of communication technology and also a challenging scientific area for new fields of research. Many contributions in ad hoc networks, such as WSNs (Wireless Sensor Networks) and VANETs (Vehicular Ad Hoc Networks), have been proposed. Nowadays, the huge amount of cars in transit has raised a big interest in vehicular communication technologies. A new type of network has been developed, named HSVN (Hybrid Sensor and Vehicular Network) in which WSNs and VANETs cooperate with the aim of improving road safety. Recent projects, such as CVIS [1] and COMeSafety [2], are focused on improving the road driving. This type of approaches will warn the driver and the co-pilot of any event occurred in the road ahead, such as traffic jam, accidents, bad weather, etc. This way, the number of traffic accidents may decrease and many lives might be saved. Besides, a better selection of non-congested roads will help to reduce pollution. In addition, other attractive services, such as downloading of multimedia services or Internet browsing, would be easily available through infrastructure along the roadside. Transportation in motorways will be easier, safer and more comfortable for passengers. In this paper a HSVN platform is presented, also a communications protocol between VANETs and WSNs is described and evaluated using the NCTUns [3] simulator.Postprint (published version

Performance Evaluation of Vehicular Ad Hoc Networks using simulation tools

Recent studies demonstrate that the routing protocol performances in vehicular networks can improve using dynamic information on the traffic conditions. WSNs (Wireless Sensor Networks) and VANETs (Vehicular Ad Hoc Networks) are exactly related with this statement and represent the trend of wireless networks research program in the last years. In this context, a new type of network has been developed: in fact, HSVN (Hybrid Sensor and Vehicular Network) let WSNs and VANETs cooperate through dynamic information data exchanges with the aim to improve road safety, and especially to warn the driver and the co-pilot of any event occurred in the road ahead, such as traffic jam, accidents or bad weather. The results will be immediate: less accidents means more saved lives, less traffic means a pollution decrease, and from the technological point of view, this communication protocol will open the door to attractive services, such as downloading of multimedia services or internet browsing, that means easier, safer and more comfortable trips. It is out of doubt that speaking about cars and road technology developments, the market and the interests about this field increase exponentially. Recent projects such as CVIS [1] and COMeSafety [2], focused on improving the road driving, and are the concrete demonstration that this entire context can get soon very close to reality. Owing to their peculiar characteristics, VANETs require the definition of specific networking techniques, whose feasibility and performance are usually tested by means of simulation. Starting from this point, this project will present a HSVN platform, and will also introduce and evaluate a communication protocol between VANETs and WSNs using the NCTUns 6.0 [3] simulator. We will particularly analyze the performances of 2 types of Scenarios developed during our project. Both of them are in an urban context, but we will extract different useful results analyzing the packet losses, the throughput and the end-to-end packet delay

Quality of Service in Vehicular Ad Hoc Networks: Methodical Evaluation and Enhancements for ITS-G5

After many formative years, the ad hoc wireless communication between vehicles has become a vehicular technology available in mass production cars in 2020. Vehicles form spontaneous Vehicular Ad Hoc Networks (VANETs), which enable communication whenever vehicles are nearby without need for supportive infrastructure. In Europe, this communication is standardised comprehensively as Intelligent Transport Systems in the 5.9 GHz band (ITS-G5). This thesis centres around Quality of Service (QoS) in these VANETs based on ITS-G5 technology. Whilst only a few vehicles communicate, radio resources are plenty, and channel congestion is a minor issue. With progressing deployment, congestion control becomes crucial to preserve QoS by preventing high latencies or foiled information dissemination. The developed VANET simulation model, featuring an elaborated ITS-G5 protocol stack, allows investigation of QoS methodically. It also considers the characteristics of ITS-G5 radios such as the signal attenuation in vehicular environments and the capture effect by receivers. Backed by this simulation model, several enhancements for ITS-G5 are proposed to control congestion reliably and thus ensure QoS for its applications. Modifications at the GeoNetworking (GN) protocol prevent massive packet occurrences in a short time and hence congestion. Glow Forwarding is introduced as GN extension to distribute delay-tolerant information. The revised Decentralized Congestion Control (DCC) cross-layer supports low-latency transmission of event-triggered, periodic and relayed packets. DCC triggers periodic services and manages a shared duty cycle budget dedicated to packet forwarding for this purpose. Evaluation in large-scale networks reveals that this enhanced ITS-G5 system can reliably reduce the information age of periodically sent messages. The forwarding budget virtually eliminates the starvation of multi-hop packets and still avoids congestion caused by excessive forwarding. The presented enhancements thus pave the way to scale up VANETs for wide-spread deployment and future applications

Quality of service and security in future mobile technologies

Future networks will comprise a wide variety of wireless networks. Users will expect to be always connected from any location, and, as users move, connections will be switched to available networks using vertical handover techniques. The current approach of the operators is a centralized network, and the mobility management is done at the infrastructure level. The decentralized mobility management is another approach developed in many researches, however, not widely deployed. We are interested in this type of decentralized mobility management, especially in a highly dynamic environment when the network topology changes frequently. We choose a particular case study, Vehicular Ad-hoc Networks (VANETs), which are a new emerging network technology derived from ad-hoc networks and are an example of future networks. In the field of Intelligent Transportation Systems (ITS), communications without a wire between vehicles (V2V) appear as an accident prevention solution offering a wider vision than conventional sensors. By linking vehicles to telecommunications network (V2I), new perspectives are offered both passengers and driver with conventional communication applications such as access Internet, e-learning, games or chat. This means that future mobile networks like VANETs will have to integrate communications, mobility, Quality of Service (QoS) and security. We mainly interested in three issues: mobility, QoS and security. These three issues are intrinsic to vehicles on motorway networks. We need to simultaneously manage QoS and security while taking into account users mobility. In this thesis, we propose to contribute on how to improve security without degrading the quality of service QoS in a highly mobile environment as VANETs networks. To answer this research question, we use simulations and experiments. Simulation using Network Simulator 2 (NS2) will be used to show that security schemes have significant impacts on the throughput QoS, and our proposed schemes can substantially improve the effective secure throughput with cooperative communications

Fixed chain-based wireless sensor network for intelligent transportation systems

Wireless Sensor Networks (WSNs) are distributed and interconnected wirelessly sensors that are used in a variety of fields of our daily life, such as the manufacturing, utility operations and traffic monitoring. Many WSN applications come with some technical weaknesses and issues, especially when they are used in Intelligent Transportation Systems (ITS). For ITS applications that use a fixed chain topology which contains road studs deployed at ground level, there are some challenges related to radio propagation, energy constraints and the Media Access Control (MAC) protocol. This thesis develops a ground level radio propagation model for communication between road studs, and energy efficiency metrics to manage the resources to overcome the energy constraints, as well as a MAC protocol compatible with chain topology and ground level communication. For the challenges of the physical layer, this thesis investigates the use of a WSN for communicating between road-based nodes. These nodes are situated at ground level, and two-way wireless communication is required between the nodes and from the nodes to a roadside control unit. Field measurements have been carried out to examine the propagation close to the ground to determine the maximum distance between road-based nodes as a function of the antenna height. The results show that for a frequency of 2.4 GHz, a range of up to 8m is achievable with 2mW equivalent isotropically radiated power (EIRP). An empirical near-ground level radio propagation model has been derived, and the predicted results from this model are shown to match closely to the measured results. Since wireless sensor networks have power constraints, green energy efficiency metrics have been proposed for low-power wireless sensors operating at ground level. A numerical analysis is carried out to investigate the utilisation of the green energy efficiency metrics for ground level communication in wireless sensor networks. The proposed metrics have been developed to calculate the optimal sensor deployment, antenna height and energy efficiency level for the near ground wireless sensor. As an application of the proposed metrics, the relationship between the energy efficiency and the spacing between the wireless sensor nodes has been studied. The results provide guidance for energy efficient deployment of near ground level wireless sensors. To manage the communication between large numbers of nodes deployed on a chain topology, this research presents a time division multiple access (TDMA) MAC protocol that is specifically designed for applications requiring periodic sensing of the sensor field. Numerical analysis has been conducted to investigate the optimum transmission scheduling based on the signal-to-interference-plus-noise-ratio (SINR) for ground level propagation model applied on wireless chain topology. The optimised transmission schedule considers the SINR value to enable simultaneous transmission from multiple nodes. The most significant advantages of this approach are reduced delay and improved Packet Received Ratio (PRR). Simulation is performed to evaluate the proposed protocol for intelligent transport system applications. The simulation results validate the MAC protocol for a fixed chain topology compared with similar protocols

Information collection algorithm for vehicular ad-hoc networks (application domain: Urban Traffic Wireless Vehicular Ad-Hoc Networks (VANETs))

Vehicle to vehicle communication (V2VC) is one of the modern approaches for exchanging and generating traffic information with (yet to be realized) potential to improve road safety, driving comfort and traffic control. In this research, we present a novel algorithm which is based on V2V communication, uses in-vehicle sensor information and in collaboration with the other vehicles' sensor information can detect road conditions and determine the geographical area where this road condition exists – e.g. geographical area where there is traffic density, unusual traffic behaviour, a range of weather conditions (raining), etc. The algorithms' built-in automatic geographical restriction of the data collection, aggregation and dissemination mechanisms allows warning messages to be received by any car, not necessarily sharing the identified road condition, which may then be used to identify the optimum route taken by the vehicle e.g. avoid bottlenecks or dangerous areas including accidents or congestions on their current routes. This research covers the middle ground between MANET [1] and collaborative data generation based on knowledge granularity (aggregation). It investigates the possibility of designing, implementing and modelling of the functionality of an algorithm (as part of the design of an intelligent node in an Intelligent Transportation System - ITS) that ensures active participation in the formation, routing and general network support of MANETs and also helps in-car traffic information and real-time control generation and distribution. The work is natural extension of the efforts of several large EU projects like DRIVE [2], GST [3] and SAFESPOT [4]

Performance Evaluation of Vehicular Ad Hoc Networks using simulation tools

Recent studies demonstrate that the routing protocol performances in vehicular networks can improve using dynamic information on the traffic conditions. WSNs (Wireless Sensor Networks) and VANETs (Vehicular Ad Hoc Networks) are exactly related with this statement and represent the trend of wireless networks research program in the last years. In this context, a new type of network has been developed: in fact, HSVN (Hybrid Sensor and Vehicular Network) let WSNs and VANETs cooperate through dynamic information data exchanges with the aim to improve road safety, and especially to warn the driver and the co-pilot of any event occurred in the road ahead, such as traffic jam, accidents or bad weather. The results will be immediate: less accidents means more saved lives, less traffic means a pollution decrease, and from the technological point of view, this communication protocol will open the door to attractive services, such as downloading of multimedia services or internet browsing, that means easier, safer and more comfortable trips. It is out of doubt that speaking about cars and road technology developments, the market and the interests about this field increase exponentially. Recent projects such as CVIS [1] and COMeSafety [2], focused on improving the road driving, and are the concrete demonstration that this entire context can get soon very close to reality. Owing to their peculiar characteristics, VANETs require the definition of specific networking techniques, whose feasibility and performance are usually tested by means of simulation. Starting from this point, this project will present a HSVN platform, and will also introduce and evaluate a communication protocol between VANETs and WSNs using the NCTUns 6.0 [3] simulator. We will particularly analyze the performances of 2 types of Scenarios developed during our project. Both of them are in an urban context, but we will extract different useful results analyzing the packet losses, the throughput and the end-to-end packet delay