Network parameters impact on dynamic transmission power control in vehicular ad hoc networks

International audienceIn vehicular ad hoc networks, the dynamic change in transmission power is very effective to increase the throughput of the wireless vehicular network and decrease the delay of the message communication between vehicular nodes on the highway. Whenever an event occurs on the highway, the reliability of the communication in the vehicular network becomes so vital so that event created messages should reach to all the moving network nodes. It becomes necessary that there should be no interference from outside of the network and all the neighbor nodes should lie in the transmission range of the reference vehicular node. Transmission range is directly proportional to the transmission power the moving node. If the transmission power will be high, the interference increases that can cause higher delay in message reception at receiver end, hence the performance of the network decreased. In this paper, it is analyzed that how transmission power can be controlled by considering other different parameter of the network such as; density, distance between moving nodes, different types of messages dissemination with their priority, selection of an antenna also affects the transmission power. The dynamic control of transmission power in VANET serves also for the optimization of the resources where it needs, can be decreased and increased depending on the circumstances of the network. Different applications and events of different types also cause changes in transmission power to enhance the reachability. The analysis in this paper is comprised of density, distance with single hop and multi hop message broadcasting based dynamic transmission power control as well as antenna selection and applications based. Some summarized tables are produced according to the respective parameters of the vehicular network. At the end some valuable observations are made and discussed in detail

Supporting Protocols for Structuring and Intelligent Information Dissemination in Vehicular Ad Hoc Networks

The goal of this dissertation is the presentation of supporting protocols for structuring and intelligent data dissemination in vehicular ad hoc networks (VANETs). The protocols are intended to first introduce a structure in VANETs, and thus promote the spatial reuse of network resources. Segmenting a flat VANET in multiple cluster structures allows for more efficient use of the available bandwidth, which can effectively increase the capacity of the network. The cluster structures can also improve the scalability of the underlying communication protocols. The structuring and maintenance of the network introduces additional overhead. The aim is to provide a mechanism for creating stable cluster structures in VANETs, and to minimize this associated overhead. Further a hybrid overlay-based geocast protocol for VANETs is presented. The protocol utilizes a backbone overlay virtual infrastructure on top of the physical network to provide geocast support, which is crucial for intervehicle communications since many applications provide group-oriented and location-oriented services. The final contribution is a structureless information dissemination scheme which creates a layered view of road conditions with a diminishing resolution as the viewing distance increases. Namely, the scheme first provides a high-detail local view of a given vehicle\u27s neighbors and its immediate neighbors, which is further extended when information dissemination is employed. Each vehicle gets aggregated information for road conditions beyond this extended local view. The scheme allows for the preservation of unique reports within aggregated frames, such that safety critical notifications are kept in high detail, all for the benefit of the driver\u27s improved decision making during emergency scenarios

Detecting Non-Line of Sight to Prevent Accidents in Vehicular Ad hoc Networks

There are still many challenges in the field of VANETs that encouraged researchers to conduct further investigation in this field to meet these challenges. The issue pertaining to routing protocols such as delivering the warning messages to the vehicles facing Non-Line of Sight (NLOS) situations without causing the storm problem and channel contention, is regarded as a serious dilemma which is required to be tackled in VANET, especially in congested environments. This requires the designing of an efficient mechanism of routing protocol that can broadcast the warning messages from the emergency vehicles to the vehicles under NLOS, reducing the overhead and increasing the packet delivery ratio with a reduced time delay and channel utilisation. The main aim of this work is to develop the novel routing protocol for a high-density environment in VANET through utilisation of its high mobility features, aid of the sensors such as Global Positioning System (GPS) and Navigation System (NS). In this work, the cooperative approach has been used to develop the routing protocol called the Co-operative Volunteer Protocol (CVP), which uses volunteer vehicles to disseminate the warning message from the source to the target vehicle under NLOS issue; this also increases the packet delivery ratio, detection of NLOS and resolution of NLOS by delivering the warning message successfully to the vehicle under NLOS, thereby causing a direct impact on the reduction of collisions between vehicles in normal mode and emergency mode on the road near intersections or on highways. The cooperative approach adopted for warning message dissemination reduced the rebroadcast rate of messages, thereby decreasing significantly the storm issue and the channel contention. A novel architecture has been developed by utilising the concept of a Context-Aware System (CAS), which clarifies the OBU components and their interaction with each other in order to collect data and take the decisions based on the sensed circumstances. The proposed architecture has been divided into three main phases: sensing, processing and acting. The results obtained from the validation of the proposed CVP protocol using the simulator EstiNet under specific conditions and parameters showed that performance of the proposed protocol is better than that of the GRANT protocol with regard to several metrics such as packet delivery ratio, neighbourhood awareness, channel utilisation, overhead and latency. It is also successfully shown that the proposed CVP could detect the NLOS situation and solves it effectively and efficiently for both the intersection scenario in urban areas and the highway scenario

Routing protocol evaluation and development of a fully functional simulation environment for vehicular ad hoc networks

A Vehicular Ad-hoc Networks (VANET) is an area of wireless technologies that are attracting a great deal of interest. There are still several areas of VANETS, such as medium access control, security and routing protocols, that lack large amounts of research. There is also a lack of freely available simulators that can quickly and accurately simulate VANETs. One of the two main goals of this thesis was to develop a freely available VANET simulator and to evaluate popular mobile ad-hoc network routing protocols in several VANET scenarios. The VANET simulator consisted of a network simulator, a traffic (mobility simulator) and used a client-server application to keep the two simulators in sync. The VANET simulator also models buildings in order to create a more realistic wireless network environment. The second main goal of this thesis was to provide an evaluation of the routing protocols that are commonly used in mobile ad-hoc networks, which will apply to VANETs. Ad-Hoc Distance Vector routing (AODV), Dynamic Source Routing (DSR) and Dynamic MANET On-demand (DYMO) were initially simulated in a city, country, and highway environment in order to provide an overall evaluation

A Framework for Incident Detection and notification in Vehicular Ad-Hoc Networks

The US Department of Transportation (US-DOT) estimates that over half of all congestion events are caused by highway incidents rather than by rush-hour traffic in big cities. The US-DOT also notes that in a single year, congested highways due to traffic incidents cost over $75 billion in lost worker productivity and over 8.4 billion gallons of fuel. Further, the National Highway Traffic Safety Administration (NHTSA) indicates that congested roads are one of the leading causes of traffic accidents, and in 2005 an average of 119 persons died each day in motor vehicle accidents. Recently, Vehicular Ad-hoc Networks (VANET) employing a combination of Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) wireless communication have been proposed to alert drivers to traffic events including accidents, lane closures, slowdowns, and other traffic-safety issues. In this thesis, we propose a novel framework for incident detection and notification dissemination in VANETs. This framework consists of three main components: a system architecture, a traffic incident detection engine and a notification dissemination mechanism. The basic idea of our framework is to collect and aggregate traffic-related data from passing cars and to use the aggregated information to detect traffic anomalies. Finally, the suitably filtered aggregated information is disseminated to alert drivers about traffic delays and incidents. The first contribution of this thesis is an architecture for the notification of traffic incidents, NOTICE for short. In NOTICE, sensor belts are embedded in the road at regular intervals, every mile or so. Each belt consists of a collection of pressure sensors, a simple aggregation and fusion engine, and a few small transceivers. The pressure sensors in each belt allow every message to be associated with a physical vehicle passing over that belt. Thus, no one vehicle can pretend to be multiple vehicles and then, is no need for an ID to be assigned to vehicles. Vehicles in NOTICE are fitted with a tamper-resistant Event Data Recorder (EDR), very much like the well-known black-boxes onboard commercial aircraft. EDRs are responsible for storing vehicles behavior between belts such as acceleration, deceleration and lane changes. Importantly, drivers can provide input to the EDR, using a simple menu, either through a dashboard console or through verbal input. The second contribution of this thesis is to develop incident detection techniques that use the information provided by cars in detecting possible incidents and traffic anomalies using intelligent inference techniques. For this purpose, we developed deterministic and probabilistic techniques to detect both blocking incidents, accidents for examples, as well as non-blocking ones such as potholes. To the best of our knowledge, our probabilistic technique is the first VANET based automatic incident detection technique that is capable of detecting both blocking and non blocking incidents. Our third contribution is to provide an analysis for vehicular traffic proving that VANETs tend to be disconnected in many highway scenarios, consisting of a collection of disjoint clusters. We also provide an analytical way to compute the expected cluster size and we show that clusters are quite stable over time. To the best of our knowledge, we are the first in the VANET community to prove analytically that disconnection is the norm rather than the exceptions in VANETs. Our fourth contribution is to develop data dissemination techniques specifically adapted to VANETs. With VANETs disconnection in mind, we developed data dissemination approaches that efficiently propagate messages between cars and belts on the road. We proposed two data dissemination techniques, one for divided roads and another one for undivided roads. We also proposed a probabilistic technique used by belts to determine how far should an incident notification be sent to alert approaching drivers. Our fifth contribution is to propose a security technique to avoid possible attacks from malicious drivers as well as preserving driver\u27s privacy in data dissemination and notification delivery in NOTICE. We also proposed a belt clustering scheme to reduce the probability of having a black-hole in the message dissemination while reducing also the operational burden if a belt is compromised

Performance evaluation of Vehicular Ad Hoc Networks over high speed environment using NCTUns

Català: Cada any aproximadament un milió dues-centes mil persones moren en accidents de trànsit. D'aquesta dada es desprèn que els accidents de trànsit són la quarta causa de mortalitat al món. Degut a això, un gran nombre de governs i els majors fabricants de vehicles del món estan invertint temps i diners en recerca i desenvolupament per millorar la seguretat a les carreteres. Amb aquest objectiu, apareix el concepte de VANET: Vehicular Ad-hoc NETwork. Una VANET està basada en vehicles i estacions base intel·ligents que comparteixen informació a través de comunicacions inalàmbriques. Aquest intercanvi de dades podria tenir un gran impacte en la seguretat viària i la qualitat en la conducció però a més a més seria una nova font d' entreteniment mòbil. La millora en seguretat implicaria una reducció en el nombre d'accidents i les comunicacions inalàmbriques usades en mobilitat permetrien una optimització del transport. L'evolució de les VANETs en els últims anys i les seves aplicacions útils a les carreteres són les principals raons per dur a terme aquest projecte. El gran suport a aquest tipus de xarxes inalàmbriques sembla indicar que les VANETs són les xarxes del futur en entorns mòbils. En relació al projecte, el primer problema observat és que el protocol que s'usa específicament en VANETs (802.11p) només està disponible en pocs simuladors de xarxa i està en fase de desenvolupament. Per tant, la majoria de les funcions no estan implementades i això fa que el protocol no sigui madur. En conseqüència, es va triar un protocol àmpliament usat com és 802.11b per fer les proves en el simulador NCTUns. L?objectiu del projecte és avaluar el funcionament de VANETs usant el protocol 802.11b i el protocol d?encaminament AODV en un escenari d?autopista. Ajustant diferents paràmetres com el nombre de cotxes, la seva velocitat i el seu rang de cobertura és possible obtenir variacions en les mesures de pèrdues, throughput i retard extrem-a-extrem en la xarxa. El resultat final és que les mesures permeten saber quines són les comunicacions que es produeixen a la xarxa per cadascuna de les configuracions i la seva incidència en les condicions de conducció.Castellano: Cada año cerca de un millón doscientas mil personas fallecen en accidentes de tráfico. De este dato se desprende que los accidentes de tráfico son la cuarta causa de mortalidad en el mundo. Debido a esto, un gran número de gobiernos y los mayores fabricantes de vehículos del mundo están invirtiendo tiempo y dinero en investigación y desarrollo para mejorar la seguridad en las carreteras. Con este objetivo, aparece el concepto de VANET: Vehicular Ad-hoc NETwork. Una VANET se basa en vehículos y estaciones base inteligentes que comparten información por medio de comunicaciones inalámbricas. Este intercambio de datos podría tener un gran impacto en la seguridad vial y en la calidad de la conducción pero además sería una nueva fuente de entretenimiento móvil. La mejora en la seguridad implicaría una reducción en el número de accidentes y las comunicaciones inalámbricas utilizadas en movilidad permitirían optimizar el transporte. La evolución de las VANETs en los últimos años y sus aplicaciones útiles en las carreteras son las principales razones para llevar a cabo este proyecto. El gran apoyo a este tipo de redes inalámbricas parece indicar que las VANETs son las redes del futuro en entornos móviles. En relación al proyecto, el primer problema observado es que el protocolo específicamente utilizado en VANETs (802.11p) sólo está disponible en pocos simuladores de red y se encuentra en fase de desarrollo. Por lo tanto, la mayoría de funciones no están implementadas y esto hace que el protocolo no sea maduro. En consecuencia, se escogió un protocolo ampliamente utilizado como es 802.11b para realizar las pruebas en el simulador NCTUns. El objetivo del proyecto es evaluar el funcionamiento de VANETs utilizando el protocolo 802.11b y el protocolo de encaminamiento AODV en un escenario de autopista. Ajustando diferentes parámetros como el número de coches, su velocidad y su rango de cobertura es posible obtener variaciones en las medidas de pérdidas, throughput y retardo extremo-a-extremo en la red. El resultado final es que las medidas permiten saber cuáles son las comunicaciones que se producen en la red para cada una de las configuraciones y su incidencia en las condiciones de conducción.English: Every year about 1.2 million people die because of traffic accidents [1]. This means that traffic accidents are the fourth cause of mortality in the world. Therefore, several governments and the most important car manufacturers are investing time and money on research and development in order to improve road safety. At this respect, appears the concept of VANET: Vehicular Ad-hoc NETwork. A VANET is based on smart cars and base-stations that share information via wireless communications. This interchange of data may have a great impact on safety and driving quality but also could be another source of mobile entertainment. This improvement on safety would imply reducing the number of accidents. In addition, the use of wireless communications in mobility would lead to an optimization of transport. The evolution of VANETs in the last years and their useful applications on the road has been the main reason to develop this project. The great support of many people to this type of wireless networks suggests that VANETs are the networks of the future in mobile environments. Regarding the project, the first problem encountered is that the network protocol specially designed for VANETs, IEEE 802.11p, is only available in a few of the network simulators and is on phase of development. This fact means that most of the functions are not implemented so it cannot be considered as a mature protocol. As a consequence, a widely used protocol as IEEE 802.11b was chosen and all the tests were performed on NCTUns simulator. So the purpose of this project is to evaluate the performance of VANETs by using 802.11b protocol and AODV routing protocol in a highway scenario. By adjusting different parameters like number of cars, their speed and their range of coverage, variations on measures of loss ratio, throughput and end-to- end delay were detected on the network. Finally, the measures help to know about network communications for each of the cases and their incidence on driving conditions

A Framework for Dynamic Traffic Monitoring Using Vehicular Ad-Hoc Networks

Traffic management centers (TMCs) need high-quality data regarding the status of roadways for monitoring and delivering up-to-date traffic conditions to the traveling public. Currently this data is measured at static points on the roadway using technologies that have significant maintenance requirements. To obtain an accurate picture of traffic on any road section at any time requires a real-time probe of vehicles traveling in that section. We envision a near-term future where network communication devices are commonly included in new vehicles. These devices will allow vehicles to form vehicular networks allowing communication among themselves, other vehicles, and roadside units (RSUs) to improve driver safety, provide enhanced monitoring to TMCs, and deliver real-time traffic conditions to drivers. In this dissertation, we contribute and develop a framework for dynamic trafficmonitoring (DTMon) using vehicular networks. We introduce RSUs called task organizers (TOs) that can communicate with equipped vehicles and with a TMC. These TOs can be programmed by the TMC to task vehicles with performing traffic measurements over various sections of the roadway. Measurement points for TOs, or virtual strips, can be changed dynamically, placed anywhere within several kilometers of the TO, and used to measure wide areas of the roadway network. This is a vast improvement over current technology. We analyze the ability of a TO, or multiple TOs, to monitor high-quality traffic datain various traffic conditions (e.g., free flow traffic, transient flow traffic, traffic with congestion, etc.). We show that DTMon can accurately monitor speed and travel times in both free-flow and traffic with transient congestion. For some types of data, the percentage of equipped vehicles, or the market penetration rate, affects the quality of data gathered. Thus, we investigate methods for mitigating the effects of low penetration rate as well as low traffic density on data quality using DTMon. This includes studying the deployment of multiple TOs in a region and the use of oncoming traffic to help bridge gaps in connectivity. We show that DTMon can have a large impact on traffic monitoring. Traffic engineers can take advantage of the programmability of TOs, giving them the ability to measure traffic at any point within several km of a TO. Most real-time traffic maps measure traffic at midpoint of roads between interchanges and the use of this framework would allow for virtual strips to be placed at various locations in between interchanges, providing fine-grained measurements to TMCs. In addition, the measurement points can be adjusted as traffic conditions change. An important application of this is end-of-queue management. Traffic engineers are very interested in deliver timely information to drivers approaching congestion endpoints to improve safety. We show the ability of DTMon in detecting the end of the queue during congestion

Advances in Vehicular Ad-hoc Networks (VANETs): challenges and road-map for future development

Recent advances in wireless communication technologies and auto-mobile industry have triggered a significant research interest in the field of vehicular ad-hoc networks (VANETs) over the past few years. A vehicular network consists of vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications supported by wireless access technologies such as IEEE 802.11p. This innovation in wireless communication has been envisaged to improve road safety and motor traffic efficiency in near future through the development of intelligent transportation system (ITS). Hence, governments, auto-mobile industries and academia are heavily partnering through several ongoing research projects to establish standards for VANETs. The typical set of VANET application areas, such as vehicle collision warning and traffic information dissemination have made VANET an interesting field of mobile wireless communication. This paper provides an overview on current research state, challenges, potentials of VANETs as well as the ways forward to achieving the long awaited ITS

SIMULATION AND ANALYSIS OF VEHICULAR AD-HOC NETWORKS IN URBAN AND RURAL AREAS

According to the American National Highway Traffic Safety Administration, in 2010, there were an estimated 5,419,000 police-reported traffic crashes, in which 32,885 people were killed and 2,239,000 people were injured in the US alone. Vehicular Ad-Hoc Network (VANET) is an emerging technology which promises to decrease car accidents by providing several safety related services such as blind spot, forward collision and sudden braking ahead warnings. Unfortunately, research of VANET is hindered by the extremely high cost and complexity of field testing. Hence it becomes important to simulate VANET protocols and applications thoroughly before attempting to implement them. This thesis studies the feasibility of common mobility and wireless channel models in VANET simulation and provides a general overview of the currently available VANET simulators and their features. Six different simulation scenarios are performed to evaluate the performance of AODV, DSDV, DSR and OLSR Ad-Hoc routing protocols with UDP and TCP packets. Simulation results indicate that reactive protocols are more robust and suitable for the highly dynamic VANET networks. Furthermore, TCP is found to be more suitable for VANET safety applications due to the high delay and packet drop of UDP packets.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

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]