Keyvan Ansari

Intelligent transportation and autonomous mobility solutions rely on cooperative awareness developed by exchanging proximity and mobility data among road users. To maintain pervasive awareness on roads, all vehicles and vulnerable road users must be identified, either cooperatively, where road users equipped with wireless capabilities of Vehicle-to-Everything (V2X) radios can communicate with one another, or passively, where users without V2X capabilities are detected by means other than V2X communications. This necessitates the establishment of a communications channel among all V2X-enabled road users, regardless of whether their underlying V2X technology is compatible or not. At the same time, for cooperative awareness to realize its full potential, non-V2X-enabled road users must also be communicated with where possible or, leastwise, be identified passively. However, the question is whether current V2X technologies can provide such a welcoming heterogeneous road environment for all parties, including varying V2X-enabled and non-V2X-enabled road users? This paper investigates the roles of a propositional concept named Augmenting V2X Roadside Unit (A-RSU) in enabling heterogeneous vehicular networks to support and benefit from pervasive cooperative awareness. To this end, this paper explores the efficacy of A-RSU in establishing pervasive cooperative awareness and investigates the capabilities of the available communication networks using secondary data. The primary findings suggest that A-RSU is a viable solution for accommodating all types of road users regardless of their V2X capabilities.

This paper offers a cloud computing architecture supporting Navigation-as-a-Service (NAVaaS) for Cooperative Intelligent Transportation Systems (C-ITS) to ensure interoperability among C-ITS users, i.e., users of single-and multi-Global Navigation Satellite Systems (GNSS) receivers. The proposed architecture, namely, Cloud Computing on Cooperative Cars (C4S) is a tailored design for connected vehicles using Dedicated Short-Range Communications (DSRC) or cellular connections. C4S is a scalable Everything-as-a-Service (XaaS) architecture using Mobile Cloud Computing (MCC) for sharing resources, platforms, software, data and communications as services. These shared infrastructure, platform, software and communications services are distributed across clusters over a network of servers and clients complementing Vehicular Ad-hoc Networks (VANETs). C4S sits above the VANET layer of C-ITS to improve transportation in terms of safety, reliability, productivity and resilience, and environmental protection. To this end, C4S establishes itself over two levels of MCC: (1) DSRC-based local fogs and (2) the Internet-based remote cloud. This architecture made an array of novel cloud-based navigation services possible that supports VANETs. The mechanism, capacity and applications of NAVaaS are verified through a describing function model and a series of experimental studies.

Vehicular accidents are one of the deadliest safety hazards and accordingly an immense concern of individuals and governments. Although, a wide range of active autonomous safety systems, such as advanced driving assistance and lane keeping support, are introduced to facilitate safer driving experience, these stand-alone systems have limited capabilities in providing safety. Therefore, cooperative vehicular systems were proposed to fulfill more safety requirements. Most of cooperative vehicle-to-vehicle safety applications require relative positioning accuracy of decimeter with an update rate of at least 10 Hz. These requirements cannot be met via direct navigation or differential positioning techniques. This paper studies a cooperative vehicle platform that aims to facilitate real-time relative positioning (RRP) among adjacent vehicles. The developed system is capable of exchanging both GPS position solutions and raw observations using RTCM-104 format over vehicular dedicated short range communication (DSRC) links. Real-time kinematic (RTK) positioning technique is integrated into the system to enable RRP to be served as an embedded realtime warning system. The 5.9 GHz DSRC technology is adopted as the communication channel among road-side units (RSUs) and on-board units (OBUs) to distribute GPS corrections data received from a nearby reference station via the Internet using cellular technologies, by means of RSUs, as well as to exchange the vehicular real-time GPS raw observation data. Ultimately, each receiving vehicle calculates relative positions of its neighbors to attain a RRP map. A series of real-world data collection experiments was conducted to explore the synergies of both DSRC and positioning systems. The results demonstrate a significant enhancement in precision and availability of relative positioning at mobile vehicles.

In this paper, we present a pathloss characterization for vehicle-to-vehicle (V2V) communications based on empirical data collected from extensive measurement campaign performed under line-of-sight (LOS), non-line-of-sight (NLOS) and varying traffic densities. The experiment was conducted in three different V2V propagation environments: highway, suburban and urban at 5.8GHz. We developed pathloss models for each of the three different V2V environments considered. Based on a log-distance power law model, the values for the pathloss exponent and the standard deviation of shadowing were reported. The average pathloss exponent ranges from 1.77 for highway, 1.68 for the urban to 1.53 for the suburban environment. The reported results can contribute to vehicular network (VANET) simulators and can be used by system designers to develop, evaluate and validate new protocols and system designs under realistic propagation conditions.

Dedicated Short Range Communication (DSRC) is the emerging key technology supporting cooperative road safety systems within Intelligent Transportation Systems (ITS). The DSRC protocol stack includes a variety of standards such as IEEE 802.11p and SAE J2735. The effectiveness of the DSRC technology depends on not only the interoperable cooperation of these standards, but also on the interoperability of DSRC devices manufactured by various manufacturers. To address the second constraint, the SAE defines a message set dictionary under the J2735 standard for construction of device independent messages. This paper focuses on the deficiencies of the SAE J2735 standard being developed for deployment in Vehicular Ad-hoc Networks (VANET). In this regard, the paper discusses the way how a Basic Safety Message (BSM) as the fundamental message type defined in SAE J2735 is constructed, sent and received by safety-communication platforms to provide a comprehensive device-independent solution for Cooperative ITS (C-ITS). This provides some insight into the technical knowledge behind the construction and exchange of BSMs within VANET. A series of real-world DSRC data collection experiments was conducted. The results demonstrate that the reliability and throughput of DSRC highly depend on the applications utilizing the medium. Therefore, an active application-dependent medium control measure, using a novel message-dissemination frequency controller, is introduced. This application level message handler improves the reliability of both BSM transmissions/receptions and the Application layer error handling which is extremely vital to decentralized congestion control (DCC) mechanisms.