## 3 Problem Statement
### Calculating Data Freshness
The proposed method provides a higher cache hit ratio with lower network delay. Figure 5: Cache hit ratio of the caching methods in Model 4. Figure 8: Network delay of the caching methods in Model 2. Figure 6: Network delay of the caching methods in Model 1. Figure 7: Network delay of the caching methods in Model 1 without estimation. Figure 9: Network delay of the caching methods in Model 2 without prediction. The results confirm that the proposed method considerably improves the cache hit ratio without imposing network delay; this is its main merit. Traffic load is the other

Figure 11: Network delay of the caching methods in Model 3 without estimation. Table 3.0 Network delay of the caching methods in Model 4. Table 3.1 Network delay of the caching methods in Model 3. Table 3.2 Network delay of the caching methods in Model 4 without estimation. criterion for the caching methods that should be considered. Figures 14 and 15 show the traffic load of the proposed method and VLRU in the conducted simulations in four models. The average value of the imposed traffic load by the proposed method is lower than the VLRU method in Simulation Models 1 and 2. Figure 5 shows the traffic load of the chachi methods in Simulation Models 3 and 4. The traffic load of the proposed method is lower than that of the other method. The lower traffic load is the other merit of the proposed method over the previous methods. In all simulation models, in the worst case, the traffic load is equal to the traffic load of the VLRU method. The proposed method optimizes the traffic load since intermediate routers answer most requests. To evaluate the accuracy of the results, the results obtained by the proposed method



is an approach that is proposed to increase the cache hit ratio, reduce traffic load, and decrease network delay in data retrieval. In this approach, the freshness of cache data is calculated by routers and the cache decision is made based on the results. The simulation and evaluation of results represent the achievement of the expected targets of this study. The proposed approach in this research has significantly increased the cache hit ratio compared to the VLRU method by enhancing data freshness in the cache of the routers. Reducing network delays and optimizing traffic load are the other two objectives of this research. The suggested method facilitates the data exchange in communication paths between the consumer and the data producer. Predicting requests and data freshness based on traffic information for datasets and using the expected information for cache decisions by routers is another idea that can be considered for future work. In the proposed approach of this research, the routers process and calculate the data freshness and cache decision. Due to the limited resources in the IoT, using the capabilities of Software-Defined Networking can be another idea for future works. The most common advantages of SDN are separation of the control plane from the data plane, centralized network management and traffic load, scalability, improved network control and responsiveness, reliability, and reduced network latency. If the proposed approach in this paper is combined with a software-based network, control processes will be removed from the routers and performed by the central unit and the routers will be managed centrally. Centralized network management and central control can reduce network latency by reducing the computational load of routers and speeding up the necessary processing. Utilizing different hybrid machine learning algorithms [38] instead of the ANN can improve the performance of the suggested method. Conceptualization, N.H., B.A., O.F. and S.H. ; Methodology, S.P. ; Software, S.P. ; Validation, B.A. and S.S.S. ; Formal analysis, S.S.; Investigation, O.F. and S.H. ; Data curation, B.A. ; Writing--original draft, N.H. and S.P. ; Writing--review & editing, N.H., B.A., S.S.S. and S.H. ; Visualization, S.P. and S.S.S. ; Supervision, B.A. and S.H. ; Project administration, O.F. and S.H. ; Funding acquisition, O.F. and S.H.