## 3 Use of DT and FL
### IoV  
DT and FL are also widely used in IoV for resource allocation, resource sharing, traffic prediction, etc. [PERSON] et al. proposed a DT model to predict traffic data in an IoV network and \begin{table}
\begin{tabular}{c c c c c c} \hline
**Ref.** & **Year** & **Objective** & **FL** & **DT** & **Achievements** \\ \hline
[46] & 2018 & Architectural aspects & No & Yes & Elaborate the role of DT in IIoT systems \\
[47] & 2020 & Interoperability & No & Yes & A flexible solution for the interoperability of the DTs in IIoT \\
[48] & 2020 & Wireless technology and protocols & No & Yes & Development of 3 GPP for URLLC in minimizing delay and enhance reliability \\
[49] & 2021 & Fiber production & No & Yes & A DT for the digitization of fiber industry \\
[50] & 2020 & Complex systems management & No & Yes & AI and XR-enabled DT development for the management of complex systems \\
[51] & 2021 & Data management & Yes & No & FL algorithm with DRL for data management achieving 97\% accuracy \\
[52] & 2021 & TrustFed & Yes & No & Blockchain-enabled TrustFed framework to ensure fairness and trustworthiness \\
[53] & 2022 & Cyber security dataset & Yes & No & Security of IoT and IIoT. Dataset can be used for the training of FL models \\
[54] & 2021 & Data protection & Yes & No & Protection of the data using differential privacy and homomorphic encryption \\
[55] & 2022 & Multi-objective modeling and blockchain enabled system & Yes & No & Strategies, and a BEFC scheme to ensure blockchain hashing and validation \\
[56] & 2022 & Data breach protection & Yes & No & FL-based framework (SecureIIoT) to protect IIoT networks from data breach \\
[57] & 2021 & Defensive transmission model & Yes & No & defensive transmission, and achieved \\  & & & & & 98\% accuracy \\
[58] & 2021 & FTL for low computing power & & FTL for low computing power IIoT gadgets & FTL and achieved accuracy of more than 70\% for the KDD99 dataset \\
[59] & 2021 & Intrusion detection & Yes & No & FL-based intrusion detection system for IIoT networks with improved efficiency \\
[60] & 2021 & Intrusion detection & Yes & No & FL-based intrusion detection in SDN-enabled IIoT networks \\
[61] & 2022 & Cyber threat hunting & Yes & No & FL-based cyber-threat hunting model for IIoT networks based on the blockchain technology \\
[62] & 2021 & Communication-effective FEL in & Yes & No & Communication-effective FEL algorithm \\  & & NRU & & NRU-based IIoT networks \\
[63] & 2021 & Authentication and privacy preservation & Yes & No & Novel algorithm based on FTL for the authentication and privacy preservation of the IIoT network \\ \hline \end{tabular}
\end{table} 
Table 3: Summary of the use of DT and FL in IIoT. improve accuracy and response time [64]. Similarly, the authors investigated DT for the dynamic resource allocation in an aerial-assisted IoV network [65]. [PERSON] et al. presented a DT model to evaluate and validate the charging recommendation design [66]. [PERSON] et al. designed DT for remote resource sharing in IoV and applied a consortium blockchain to track and secure resource sharing [67]. [PERSON] et al. proposed a DT model for efficient and quick resource sharing in an unmanned aerial vehicle (UAV)-based IoV network [68]. Several articles used FL in the IoV. [PERSON] et al. presented an asynchronous FL approach to implement secure and effective data sharing in IoV networks [69]. Similarly, the researchers proposed a FL-based model for the improved TCP performance of the IoV network over WiFi [70]. [PERSON] et al. proposed a blockchain-enabled FL algorithm for improved knowledge sharing in IoV networks [71]. Moreover, the authors proposed a novel FL model for efficient license plate recognition in 5G-enabled IoV [72]. [PERSON] et al. proposed a dual-layer FL and heterogeneous model aggregation for the efficient communication and privacy preservation of 6G-enabled IoV [73]. [PERSON] et al. demonstrated FL-based cooperative positioning in the IoV network for autonomous driving and collision avoidance [74]. [PERSON] et al.