Evaluating network technologies for industrial intelligent transportation systems.

Type of content
Theses / Dissertations
Publisher's DOI/URI
Thesis discipline
Computer Science
Computer Science
Degree name
Master of Science
Publisher
University of Canterbury
Journal Title
Journal ISSN
Volume Title
Language
English
Date
2021
Authors
Pell, Samuel
Abstract

An Intelligent Transportation System (ITS) is a network of connected vehicles, pedestrians, and infrastructure sharing information to improve safety and efficiency. To enable an ITS, so called vehicle-to-everything (V2X) technologies are used. V2X technologies are ad hoc wireless communication technologies which target the 5.9 GHz radio band and can handle the highly mobile vehicular environment whilst supporting the often strict service requirements of vehicular safety applications. The majority of prior research into ITS and V2X technologies has focused on traditional roads, however vehicles are also extensively used in industrial environments, which could also benefit from the safety and efficiency gains an ITS offers. This thesis investigates applying V2X technologies to safety applications in one possible industrial environment: the logistics warehouse.

In particular, two different V2X technologies (C-V2X and IEEE 802.11p) are compared, evaluated based on the error rate of an aisle-end collision warning application in warehouses, to determine which is more suited to the warehouse environment. To quantitatively evaluate the technologies an aisle-end collision scenario and collision warning application simulator was developed to simulate each technology. The simulator includes a custom warehouse aisle-end channel model which was parameterised using measurements conducted in a real-world warehouse.

Using the collision warning application simulator the application error rate was observed for each technology for different average spacing between forklifts, modulation and coding schemes (MCS), and transmit powers. It was found that the average spacing between forklifts had the most effect on the failure rate of the application. As the average spacing between forklifts decreased, the false negative rate increased relative to the baseline for C-V2X but stayed roughly constant for IEEE 802.11p. The differing behaviour of the two technologies is attributed to the different channel access procedures used by the two technologies. The effect of MCS and transmit power was negligible for IEEE 802.11p. For C-V2X however, the false negative error rate increased with MCS index and there appears to be a minimum transmit power, below which, C-V2X performs significantly worse. This behaviour is hypothesised to also be caused by C-V2X’s channel access algorithm. Based on the quantitative evaluation of the technologies, at least for the warehouse environment, IEEE 802.11p is superior to C-V2X.

In addition to the quantitative evaluation of the current generation of V2X technologies, this thesis also presents a qualitative discussion of what possible change in performance the next generation V2X technologies (NR-V2X and IEEE 802.11bd) may bring. The next generation of V2X technologies focus on improving the physical layer performance of the current generation (C-V2X and IEEE 802.11p). However, all the problems with the technologies identified in this thesis are in the channel access procedures. Thus, next generation V2X technologies are not expected to significantly improve performance in this scenario. This thesis also discusses the regulatory support for each technology in different regions. In the United States of America, C-V2X is the only V2X technology allowed to use the 5.9 GHz ITS band, making it more suitable for deployment in a warehouse ITS in that region.

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