Abstract

Vehicle-to-vehicle communications (V2V) is a promising technique for Advanced Driver Assistance Systems to increase traffic safety and efficiency. A proposed system is the Congestion Assistant, which supports drivers when approaching and driving in traffic congestion. Studies have shown great potential for such systems to reduce the impact of congestion, even at low penetration. However, these studies assumed complete and instantaneous knowledge regarding position and velocity of vehicles ahead. This paper refines and analyses the TrafficFilter, designed to supply the required information to the Congestion Assistant. Vehicles collaboratively build a so-called TrafficMap, providing over-the-horizon awareness. To this end, an improvement to the Slotted 1-Persistence Flooding called microSlotted 1-Persistence Flooding is proposed and evaluated. In a simulation study the TrafficFilter is found to be a viable system to build over-the-horizon awareness for future Advanced Driver Assistance Systems like the Congestion Assistant, without triggering the phenomenon known as Broadcast Storm.

Abstract

This thesis reviews approaches towards Cooperative Adaptive Cruise Control (CACC), identifies important simulation parameters, and analyzes their correlation with metrics that describe the performance of the application in terms of safety, efficiency and channel utilization. This is achieved through simulation of realistic traffic and V2V communication by using recent ETSI ITS standards including different GeoNetworking message dissemination mechanisms. The results show, that an increasing traffic on the network channel has a negative effect on the safety of a platooning application, but it can be compensated by using more conservative configuration parameters. This impact is increasing slightly for lower vehicle spacing, stronger for longer platoons and drastically for lower beacon rates.

Abstract

TRA 2018, 7th Transport Research Arena, Vienne, AUTRICHE, 16-/04/2018 - 19/04/2018; The Vehicular Ad-Hoc Network (VANET) paradigm offers the opportunity of extending Intelligent Transport System (ITS) by supporting its applications through vehicle-to-vehicle communications, notably in the areas where the infrastructure is inexistent, in failure, or overloaded. However, the complexity induced by ad hoc network management raises many challenges that have to be solved such as the sharing of bandwidth resources, the limitations on the duration of the connections between the vehicles, and the application-specific quality of service (QoS) requirements. Recently, the Chain-Branch-Leaf clustering scheme (CBL) has been proposed for vehicle-to-vehicle ad hoc routing that combines the information of road configuration, vehicle mobility, and link quality in order to build an efficient clustering connecting the entire VANET through a flexible backbone. This work presents a comparative study between the native Multipoint relaying clustering used in the Optimized Link State Routing (OLSR) and CBL scheme. The results show that CBL reduces significantly the routing traffic overhead compared to native OLSR, thus freeing up more bandwidth for ITS applications and reducing the IP delays for peer-to-peer applications.

Abstract

Wireless vehicular ad-hoc networks comprised solely of city taxis are investigated for their ability to deliver data across an urban environment. Openly available taxi trace datasets for Rome (Italy) and San Francisco (USA) are combined with respective building footprint and road network topology data from OpenStreetMap, to generate a realistic systems level model of a taxi V2V network. Analysis of LOS and NOLOS constraints on wireless transmission range suggests a minimum threshold of 50m is applicable to ensure LOS in over 90% of cases. Variations in taxi location sampling frequency and filtering techniques for the taxi trace datasets are also investigated. Overall vehicular network performance is computed for an all-to-one transmission scenario for both cities with varying taxi fleet size. Results suggest a non-linear relationship between increases in taxi fleet sizes and the reduction of end-to-end delay; doubling taxi fleet size (using a randomised data folding technique) reduces end-to-end delay by a factor of 0.6–0.7. However, doubling the fleet does not increase the fraction of delivered source messages, which saturates at 0.67–0.71 in most simulations. Finally it appears that taxi networks for delivering messages across urban environments are limited more by their routing than by the number of possible V2V exchanges. In a simulated one-to-all continuous V2V broadcast scenario, over 90% of the taxis within the fleet receive the source message within one hour of the original taxi passing the source node.

Abstract

The transport sector is commonly subordinate to several issues, such as traffic congestion and accidents. Despite this, in recent years, it is also evolving with regard to cooperation between vehicles. The fundamental objective of this trend is to increase road safety, attempting to anticipate the circumstances of potential danger. Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I) and Vehicle-to-Everything (V2X) technologies strive to give communication models that can be employed by vehicles in different application contexts. The resulting infrastructure is an ad-hoc mesh network whose nodes are not only vehicles but also all mobile devices equipped with wireless modules. The interaction between the multiple connected entities consists of information exchange through the adoption of suitable communication protocols. The main aim of the review carried out in this paper is to examine and assess the most relevant systems, applications, and communication protocols that will distinguish the future road infrastructures used by vehicles. The results of the investigation reveal the real benefits that technological cooperation can involve in road safety. Document type: Article