A multi-tier trust-based system for vehicle ad-hoc network communication


Student thesis: Doctoral Thesis


Vehicle ad-hoc networks (VANETs) are a particular type of mobile ad-hoc networks (MANETs) that enable vehicles to communicate in modern road environments. By enabling communication, VANETs can provide real-time information such as traffic congestion warnings, safety messages, lane change information and infotainment. VANETs lead to optimized traffic conditions, increased road safety and improved driving conditions for road users.
Accurate and timely delivery of messages is crucial due to the importance of messages transmitted. Therefore, securing communications in VANETs is crucial for operations. Messages exchanged in VANET communications contain critical information such as road safety or road accident information. These packets must reach their intended destination without modification. VANET communications are concerned that malicious vehicles can intercept or modify messages before reaching their intended destination. Malicious behaviour can hamper VANET operations and create safety concerns.
This research proposes a multi-tier trust management system based on vehicle behaviour for the detection of malicious vehicles and to improve communication within VANET. It includes investigating VANETs while highlighting vehicle behaviour metrics. The metrics include packet delivery ratio (PDR), processing delay, forwarding rate (FR), initial and residual energy, and operational history of a vehicle. The first tier of the proposed system assigns vehicles in the VANET a trust value based on behaviour such as processing delay, packet loss and prior vehicle behavioural history. To achieve this, a set of vehicles is selected as watchdogs and observes neighbouring vehicles’ behaviour. Watchdogs send this data to the roadside unit (RSU), which calculates trust values to represent vehicle behaviour. The second tier protects against malicious watchdogs in the VANET. Watchdog behaviour history identifies malicious and non-malicious watchdogs. The third security tier protects trust value calculation data. A secure watchdog selection process is proposed to enhance system robustness. This watchdog selection scheme considers vehicle behaviour and fairness while selecting watchdogs. In order to improve accuracy, the proposed system includes intelligence to identify false positives caused by network errors and malicious vehicles that recover from malicious behaviour.
Based on simulations, the developed system successfully identifies and isolates malicious vehicles in the VANET. The designed system improves the VANET packet delivery rate and reduces packet delivery delay. The proposed system's accuracy is evaluated by its ability to identify false positives and vehicles recovered from malicious behaviour. The suggested watchdog selection process successfully selects secure and fair watchdogs, improving system robustness. The proposed system enhances VANET communications. In future applications, the developed system can be applied to intelligent city environments by enabling efficient and safe transportation. Consequently improving the quality of life for its citizens.
Date of Award30 May 2023
Original languageEnglish
Awarding Institution
  • Edge Hill University
SupervisorNik Bessis (Director of Studies), HASSAN MALIK (Supervisor) & SARAH MCHALE (Supervisor)


  • Vehicle ad-hoc network (VANET)
  • Trust management systems.
  • Malicious vehicles
  • Autonomous vehicles

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