Virtual Access Points for Vehicular Networks

ABSTRACT This paper introduces the concept of Virtual Access Points (VAPs) for wireless Vehicular Ad-hoc Networks (VANETS). This new technique allows data dissemination among vehicles, thus extending the reach of roadside access points to uncovered road areas. Each vehicle that receives a message from an Access Point (AP) stores this message and rebroadcasts it into non covered areas. This extends the network coverage for non time critical messages. The VAP role is transparent to the connected nodes, and designed to avoid interference since each operates on a bounded region outside any AP. The experiments show the presented mechanism of store and forward at specific positions present a gain, in term of all the evaluated parameters

Fog Connectivity Clustering and MDP Modeling for Software-defined Vehicular Networks

Intelligent and networked vehicles cooperate to create a mobile Cloud through vehicular Fog computing (VFC). Such clouds rely heavily on the underlying vehicular networks, so estimating communication resilience allows to address the problems caused by intermittent vehicle connectivity for data transfers. Individually estimating the communication stability of vehicles, nevertheless, undergoes incorrect predictions due to their particular mobility patterns. Therefore, we provide a region-oriented fog management model based on the connectivity through vehicular heterogeneous network environment via V2X and C-V2X. A fog management strategy dynamically monitors nearby vehicles to determine distinct regions in urban centres. The model enables a software-defined vehicular network (\Gls{SDVN}) controller to coordinate data flows. The vehicular connectivity described by our model assesses the potential for vehicle communication and conducts dynamic vehicle clustering. From the stochasticity of the environment, our model is based on Markov Decision Process (MDP), tracking the status of vehicle clusters and their potential for provisioning services. The model for vehicular clustering is supported by 5G and DSRC heterogeneous networks. Simulated analyses have shown the capability of our proposed model to estimate cluster reliability in real-time urban scenarios and support effective vehicular fog management

A holistic framework to improve message delivery in vehicular ad-hoc networks

Vehicular Ad-hoc Networks (VANETs) are wireless communication networks for vehicles that do not require any fixed or central infrastructure. It forms an important part of the intelligent transport system (ITS) which is the convergence of telecommunications, computing and wireless systems with the aim of improving transportation regarding efficiency, safety and management. In addition to the uses of ITS, VANETs will contribute in service access, cooperative driving, entertainment and navigation for cars of the future. Due to the varied use of VANETs, it becomes slightly cumbersome having a "one-fits-all" solution to challenges facing message dissemination in VANETs. While some applications might require a fast and reliable way of disseminating messages amongst members of the network, other applications might be more delay-tolerant without adding extra risks to the dependents of such application. Data dissemination methods are therefore important aspects of VANET that ensure messages are delivered to areas beyond the scope of the originating node. However, several types of research have shown that message propagation for each geographical route is unique to that route, owing to the number of network participants, their speed, and distribution of objects on that route. Many research designs do not consider the vehicles and their traffic characteristics and as such vehicular ad-hoc networks are under-utilised. One of the problems present in the emerging field of vehicular communications is that of optimally disseminating messages within the network to support services such as collision warnings, traffic management, and driverless vehicles amongst others. This problem is a unique research area which involves the entire network and its ability to support the efficient propagation of data. Message dissemination in VANETs could be viewed as routing on much higher macroscopic level, however, the techniques usually applied to data routing on a microscopic level does not utilise available data to efficiently disseminate messages within a vehicular ad-hoc network. Some work done in literature addresses a few constraints at a time; for example a focus on junctions, thereby ignoring vast areas of the wireless network which could have been otherwise used to improve the overall ability to efficiently deliver messages within the road network. For this reason, this thesis investigates the effects of several vehicular factors, how these factors affect the quality of the wireless network on each road, and how this knowledge is advantageous in improving the delivery of messages from a source to its destination within a vehicular ad-hoc network. In proposing a solution that uses otherwise largely ignored road traffic data to improving efficient message delivery, a holistic framework that utilises road traffic information in a unique way is presented. The quality of a wireless network for each road in terms of packets delivered is seen to be influenced by the number of vehicles and their speed which is seen to be unique for each road segment; therefore, allowing the generation of a wireless packet delivery map offline (wireless network map) based on varying number of vehicles and speeds. Current road traffic data can then be compared against the wireless map in order to determine which routes have good network quality and hence the ability to support better message dissemination. This framework is also aimed at helping to fully utilise the VANET bandwidth available by reducing network noise caused by multiple retransmissions of nodes in the network by picking the right path and using only the furthest node on each path. It aims to reduce messages delivery failure, reduce delays in the message delivery where possible and improve the utilisation of vehicles as communication nodes and relays. The Framework for Improving Message Delivery in VANETs (FIMDEV) proposed in this thesis shows the benefit of using the wireless communication database information processed by each vehicle to support message delivery from source to destination within the VANET. Experiments show improved overall packet delivery ratio when compared to standalone routing protocols as FIMDEV uses the wireless network database along with a set of rules for propagating messages within the network