An Improved CF-MAC Protocol for VANET

Vehicular Ad hoc Network (VANET) is one of the emerging research areas in the mobile computing field which is considered as future technology and promising topic in computer science and computer networks. Which provides road safety, updated traffic information, and infotainment. VANET consists of a large number of vehicles moving in high speeds while broadcasting important information like safety and control information which must be sent with high priority. Crowded networks like VANET having many vehicles competing to reserve the channel to send critical information which may lead to high collision scenarios, and therefore, there must be a protocol to send this kind of information with high reliability, low data loss and with no collision. In this research a collision-free protocol will be proposed to manage the channel access among competing vehicles to eliminate the collisions which occur rapidly in VANET especially in dense situations, the proposed protocol hereinafter will be called (I-MAC) protocol expected to enhance the channel performance, achieve load balancing, fairness, and decrease message loss and enhance reliability, The evaluation criteria will examine the channel throughput, message delay, and message loss; the results show that the overall channel performance with regard to collision and packet loss ratio is improved

Modeling and Simulation of Vehicle to Vehicle and Infrastructure Communication in Realistic Large Scale Urban Area

During the last decades, Intelligent Transportation System (ITS) has progressed at a rapid rate, which aim to improve transportation activities in terms of safety and efficiency. Car to Car or Vehicle-to-Vehicle (V2V) communications and Car/Vehicle-to-Infrastructure (I2V or V2I) communications are important components of the ITS architecture. Communication between cars is often referred to Vehicular Ad-Hoc Networks (VANET) and it has many advantages such as: reducing cars accidents, minimizing the traffic jam, reducing fuel consumption and emissions and etc. VANET architectures have been standardized in the IEEE-802.11p specification. For a closer look on V2V and V2I studies, the necessity of simulations is obvious. Network simulators can simulate the ad-hoc network but they cannot simulate the huge traffic of cities. In order to solve this problem, this thesis studies the Veins framework which is used to run a traffic (SUMO) and a network (OMNET++) simulator in parallel and simulates the realistic traffics of the city of Cologne, Germany, as an ad-hoc network. Several different simulations and performance analyses have been done to investigate the ability of different VANET applications. In the simulations, cars move in the real map of the city of Cologne and communicate with each other and also with RoadSideUnits with using IEEE 802.11p standard. Then, Probability of Beacons Delivery (PBD) in different area of a real city are calculated and also are compared with the analytical model. This study is the first research performed on calculating PBD of IEEE 802.11p in realistic large urban area. Then, the thesis focuses on modelling and analysis of the applications of the V2I in real city. In these sections, two different simulations of application of the VANET are done by developing the Veins framework and also by developing two new programs written in Python which are connected to SUMO and control the real traffic simulation. One program simulates a real city with intelligent traffic lights for decreasing response time of emergency vehicles by using V2I. The results show that using V2I communication based on 802.11p between emergency cars and traffic lights can decrease the response time of emergency cars up to 70%. Another program, simulates dynamic route planning in real traffic simulation which is used V2I and V2V communication. The result of this simulation show the capability of V2V and V2I to decrease the traveling time, fuel consumptions and emissions of the cars in the city

Modeling and Simulation of Vehicle to Vehicle and Infrastructure Communication in Realistic Large Scale Urban Area

During the last decades, Intelligent Transportation System (ITS) has progressed at a rapid rate, which aim to improve transportation activities in terms of safety and efficiency. Car to Car or Vehicle-to-Vehicle (V2V) communications and Car/Vehicle-to-Infrastructure (I2V or V2I) communications are important components of the ITS architecture. Communication between cars is often referred to Vehicular Ad-Hoc Networks (VANET) and it has many advantages such as: reducing cars accidents, minimizing the traffic jam, reducing fuel consumption and emissions and etc. VANET architectures have been standardized in the IEEE-802.11p specification. For a closer look on V2V and V2I studies, the necessity of simulations is obvious. Network simulators can simulate the ad-hoc network but they cannot simulate the huge traffic of cities. In order to solve this problem, this thesis studies the Veins framework which is used to run a traffic (SUMO) and a network (OMNET++) simulator in parallel and simulates the realistic traffics of the city of Cologne, Germany, as an ad-hoc network. Several different simulations and performance analyses have been done to investigate the ability of different VANET applications. In the simulations, cars move in the real map of the city of Cologne and communicate with each other and also with RoadSideUnits with using IEEE 802.11p standard. Then, Probability of Beacons Delivery (PBD) in different area of a real city are calculated and also are compared with the analytical model. This study is the first research performed on calculating PBD of IEEE 802.11p in realistic large urban area. Then, the thesis focuses on modelling and analysis of the applications of the V2I in real city. In these sections, two different simulations of application of the VANET are done by developing the Veins framework and also by developing two new programs written in Python which are connected to SUMO and control the real traffic simulation. One program simulates a real city with intelligent traffic lights for decreasing response time of emergency vehicles by using V2I. The results show that using V2I communication based on 802.11p between emergency cars and traffic lights can decrease the response time of emergency cars up to 70%. Another program, simulates dynamic route planning in real traffic simulation which is used V2I and V2V communication. The result of this simulation show the capability of V2V and V2I to decrease the traveling time, fuel consumptions and emissions of the cars in the city

Assessing Mission-critical Vehicular Safety Applications under Various Network Conditions

Enabling communication among vehicles can facilitate the deployment of safety applications that can improve driving safety and reduce traffic-related fatalities. Assessing the reliability of these safety applications is essential to evaluating VANETs' contributions to improved safety and driving conditions. In this context, I maintain that reliability metrics that express the requirements of safety applications in terms of network performance are much more suitable than standalone network-level metrics, as the latter do not indicate whether the requirements of safety applications can be met. This work considers awareness as an intermediate layer between the application and the network layers, for identifying the different levels of reliability achievable by the different safety applications. Through a comprehensive simulation study, this work analyzes the level of awareness that networks can offer under various scenarios and a wide range of influencing parameters, including transmission power, message generation rate, vehicular density, message size, as well as radio propagation and fading effects. Insights are provided on how network performance metrics address application requirements and contribute to enhancing the reliability of safety applications. Finally, communication parameters necessary to offering high levels of reliability are determined for three representative safety-application requirements

A channel model and coding for vehicle to vehicle communication based on a developed V-SCME

Over the recent years, VANET communication has attracted a lot of attention due to its potential in facilitating the implementation of 'Intelligent Transport System'. Vehicular applications need to be completely tested before deploying them in the real world. In this context, VANET simulations would be preferred in order to evaluate and validate the proposed model, these simulations are considered inexpensive compared to the real world (hardware) tests. The development of a more realistic simulation environment for VANET is critical in ensuring high performance. Any environment required for simulating VANET, needs to be more realistic and include a precise representation of vehicle movements, as well as passing signals among different vehicles. In order to achieve efficient results that reflect the reality, a high computational power during the simulation is needed which consumes a lot of time. The existing simulation tools could not simulate the exact physical conditions of the real world, so results can be viewed as unsatisfactory when compared with real world experiments. This thesis describes two approaches to improve such vehicle to vehicle communication. The first one is based on the development of an already existing approach, the Spatial Channel Model Extended (SCME) for cellular communication which is a verified, validated and well-established communication channel model. The new developed model, is called Vehicular - Spatial Channel Model Extended (V-SCME) and can be utilised for Vehicle to Vehicle communication. V-SCME is a statistical channel model which was specifically developed and configured to satisfy the requirements of the highly dynamic network topology such as vehicle to vehicle communication. V-SCME provides a precise channel coefficients library for vehicle to vehicle communication for use by the research community, so as to reduce the overall simulation time. The second approach is to apply V-BLAST (MIMO) coding which can be implemented with vehicle to vehicle communication and improve its performance over the V-SCME. The V- SCME channel model with V-BLAST coding system was used to improve vehicle to vehicle physical layer performance, which is a novel contribution. Based on analysis and simulations, it was found that the developed channel model V-SCME is a good solution to satisfy the requirements of vehicle to vehicle communication, where it has considered a lot of parameters in order to obtain more realistic results compared with the real world tests. In addition, V-BLAST (MIMO) coding with the V-SCME has shown an improvement in the bit error rate. The obtained results were intensively compared with other types of MIMO coding

Design and evaluation of safety-critical applications based on inter-vehicle communication

Inter-vehicle communication has a potential to improve road traffic safety and efficiency. Technical feasibility of communication between vehicles has been extensively studied, but due to the scarcity of application-level research, communication\u27s impact on the road traffic is still unclear. This thesis addresses this uncertainty by designing and evaluating two fail-safe applications, namely, Rear-End Collision Avoidance and Virtual Traffic Lights

Towards reliable geographic broadcasting in vehicular networks

In Vehicular ad hoc Networks (VANETs), safety-related messages are broadcasted amongst cars, helping to improve drivers' awareness of the road situation. VANETs’ reliability are highly affected by channel contention. This thesis first addresses the issue of channel use efficiency in geographical broadcasts (geocasts). Constant connectivity changes inside a VANET make the existing routing algorithms unsuitable. This thesis presents a geocast algorithm that uses a metric to estimate the ratio of useful to useless packet received. Simulations showed that this algorithm is more channel-efficient than the farthest-first strategy. It also exposes a parameter, allowing it to adapt to channel load. Second, this thesis presents a method of estimating channel load for providing feedback to moderate the offered load. A theoretical model showing the relationship between channel load and the idle time between transmissions is presented and used to estimate channel contention. Unsaturated stations on the network were shown to have small but observable effects on this relationship. In simulations, channel estimators based on this model show higher accuracy and faster convergence time than by observing packet collisions. These estimators are also less affected by unsaturated stations than by observing packet collisions. Third, this thesis couples the channel estimator to the geocast algorithm, producing a closed-loop load-reactive system that allows geocasts to adapt to instantaneous channel conditions. Simulations showed that this system is not only shown to be more efficient in channel use and be able to adapt to channel contention, but is also able to self-correct suboptimal retransmission decisions. Finally, this thesis demonstrates that all tested network simulators exhibit unexpected behaviours when simulating broadcasts. This thesis describes in depth the error in ns-3, leading to a set of workarounds that allows results from most versions of ns-3 to be interpreted correctly

An analytical model for beaconing in VANETs

IEEE 802.11 CSMA/CA is generally considered to be well-understood, and many detailed models are available. However, most models focus on Unicast in small-scale W-LAN scenarios. When modelling beaconing in VANETs, the Broadcast nature and the (potentially) large number of nodes cause phenomena specific to large-scale broadcast scenarios not captured in present models of the 802.11 DCF. In a VANET scenario, transmissions from coordinated nodes are performed in so-called Streaks, without intermediate backoff counter decrement. We adapt the model by Engelstad and Østerbø and provide several improvements specific to VANET beaconing. The resulting analytical model is shown to have good fit with simulation results