An Extensive Study on the State-of-the-Art Literature to Identify Major Approaches and Trust Issues of Trust-based Models in VANETs

Therefore, Vehicular Ad-hoc Networks (VANETs) are the fundamental infrastructure required for the deployment of Intelligent Transportation Systems (ITS), which will facilitate enhanced safety, efficiency and comfort by interconnecting vehicles. Trust establishment is first and foremost for the smooth operation of VANETs, with trust appearing as necessary in the case for safe dissemination and preventive measures against malicious behaviours for nodes making use of inter-communication within the network. This paper provides a comprehensive summary of the existing trust-based models in VANETs, and takes an in-depth look into associated issues. We go through entity-centric, data-centric and hybrid models providing their strengths and limitations. This is backed by the statistics which indicate that implementing emerging technologies such as block chain and machine learning can greatly improve the reliability mechanisms. Moreover, they overcome the limitations suggested by trust models including dynamic network topology, scalability and problems related to privacy and security etc. This systematic review will facilitate the insight of researchers regarding the state-of-the-art research in trust and also highlight necessary enhancements in order to produce stable and efficient models for trust in VANETs. This highlights the need for interdisciplinary teamwork in integrating cryptographic techniques, machine learning solutions, and informative messages to develop resilient trust systems against adversarial activities on vehicular communication networks.