## 4 Results
### RQ7: Limitations of the Literature Review
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Reference** & **Title of Article** & **Proposed Solution** & **Limitations and Future Work** \\ \hline [PERSON] et al. [101] & Towards secure and provable authentication for the internet of things: realizing Industry 4.0 & The effectiveness of the developed protocol was evaluated with frequently utilized AVISPA, PUFs, and ECC encryption algorithms. A proposed technique was developed to create a durable, stable, and efficient user architecture that promotes shared authentication for IoT and server nodes and is resistant to cyber threats. & This protocol is for academic and research purposes only, and its implementation has not yet been tested in the real world. \\ \hline [PERSON] et al. [104] & Residual energy-based cluster-head selection in WSN for IoT application & The method takes into account the intended value of initial energy, residual energy, and cluster heads to choose the specific set of cluster heads in the network that adapts IoT applications to maximize flow, durability, and residual energy. & They did not review existing path selection factors in a node mobility network that altered its role constantly. \\ \[PERSON] et al. [105] & Software-defined industrial Internet of Things in the context of industry 4.0 & They proposed a new idea of information interaction in Industry 4.0 using software-defined IIoT. They enhanced the network size using IIoT. The IIoT architecture manages physical devices and information exchange methods via a customized networking protocol. & The limitation of the study is the effective coordination between IIoT where the network is heterogeneous for transmission of information. \\ \[PERSON] et al. [106] & Application of IoT-aided simulation to manufacturing systems in cyber-physical systems & They discussed the construction and implementation methods of digital twin (DT). In this study also explained the issues involved in developing DT with the help of IoT manufacturing devices. DT is the simulation tool that can gather and synchronize data for the real world to a real-time environment. & The absence of experimentation and optimization in predicting future locations or results are other essential aspects of DT. \\ \hline [PERSON] et al. [107] & DistB-SDoIndustry: enhancing security in Industry 4.0 services based on the distributed blockchain through software-defined networking-IoT enabled architecture & In this work, the authors develop a distributed blockchain-based security system integrated with the help of IoT and SDN. Blockchain is used for data security and confidentiality, while SDN-IoT incorporates sensor networks and IoT devices to improve the security services in Industry 4.0. & Limitations of this study are that the developed model SDN-IoT was still in the initial stage, so it was not able to detect different types of risks, such as service denial (DoS) and flood attack and packet filtering. The developed system had no proper GUI, so the throughput, packet arrival time, and response time were rarely challenging to analyze. \\ \hline \end{tabular}
\end{table} 
Table 9: _Cont._The limitation of this work was the high time complexity of the load balancing algorithm to complete the task efficiently. It was challenging to refine the process due to the complex nature of multi-agent technology, and referencing rules were much more complex. The design meets some disadvantages and does not work in real-time data. The limitation of this work was the high time complexity of the load balancing algorithm to complete the task efficiently. It was challenging to refine the process due to the complex nature of multi-agent technology, and referencing rules were much more complex. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Reference** & **Title of Article** & **Proposed Solution** & **Limitations and Future Work** \\ \hline \multirow{8}{*}{[PERSON] et al.