# Network Lifetime Improvement through Energy-Efficient Hybrid Routing Protocol for IoT Applications
## 4 Proposed Hybrid PSOGA
### Proposed Hybrid-Based PSOGA Routing
(**g**) Graph showing data plots of 10 simulations. (**h**) Simulation time for 10 simulations. (**i**) Error bound for alive nodes. Figure 5: Results of Case Study 2: 4 \(\times\) 4, 100 nodes. (**a**) Network structure for Case Study 2. (**b**) Packets reaching the BS. (**c**) Total alive nodes. (**d**) Total residual energy. (**e**) PDR. (**f**) Throughput. ### Case Study 3

Figure 6 shows the results of Case Study 3: 4 \(\times\) 4 grids, 200 nodes. The network structure (Figure 6a) shows 16 grids with the selected cluster heads marked in numbers and connected by a black line. The results of the performance metrics show that with 200 nodes, the packets sent to the BS (Figure 6b) with the PSOGA improved by 288.7% and 9.36% compared to LEACH and PSO, respectively. Furthermore, the number of alive nodes improved by 189.44% and 11.65% as compared to LEACH and PSO, respectively (Figure 6c). Figure 6d also demonstrates a similar trend with respect to residual energy, that is, the energy of the network was reduced to 0 after approximately 500 rounds, 1850 rounds, and 1994 rounds for LEACH, PSO, and the proposed PSOGA, respectively, contributing to improvement percentages of 279.2% and 12.5%, respectively. Similarly, the PDR was also enhanced by 304.9% and 67.3% compared to LEACH and PSO, respectively (Figure 6e). Figure 6f further demonstrates the efficacy of the PSOGA in terms of throughput improvement by 44.53% and 5.96% compared to LEACH and PSO, respectively. We compared the performance metrics of Case Study 3 to Case Study 2, in which the number of grids was the same, that is, 16, but the number of nodes was higher, that is, 200 nodes. The number of packets reaching the BS in Case Study 3 was higher, with \(3.6\times 10^{6}\) vs. \(3.5\times 10^{6}\) packets, demonstrating a slight improvement of around \(1\times 10^{5}\) packets. Moreover, in Figures 5f and 6f, minimal improvement in the throughput can be seen. ### Case Study 4

Figure 7 shows the results of Case Study 4 with \(10\times 10\) grids, 625 nodes. The network structure (Figure 7a) shows 100 grids with the selected cluster heads marked in numbers and connected by a black line. The results of the performance metrics show that with 625 nodes, the packets sent to the BS (Figure 7b) saw improvements of 325% and 30.76% as compared to LEACH and PSO, respectively. The number of alive nodes was enhanced by 232.22% and 6.26% as compared to LEACH and PSO, respectively. In Figure 7c, the residual energy improved by 298.4% and 7.67% with respect to LEACH and PSO, respectively, as shown in Figure 7d. Furthermore, in Figure 7e, the PSOGA demonstrated increases of 266.36% and 46.47% in the PDR as compared to LEACH and PSO, respectively. Similarly, Figure 7f shows increases in the throughput of the network by 46.3% and 6.87% when compared to LEACH and PSO, respectively. In Case Study 4, with 625 nodes and 100 grids, the performance of the network deteriorated as compared to the previous case studies. The number of packets sent to the base station was \(3.1\times 10^{6}\), which is substantially lower than in the previous case studies. Similarly, the PDR was also reduced to 60% from the 70% achieved in Case Study 3. The throughput achieved in Case Study 4 was 15,500, much less than the 18,000 achieved in Case Study 3. The drastic reduction in the performance metrics can be attributed to the structure, where, although the number of nodes was higher, the grid structure of \(10\times 10\) made the process of path discovery cumbersome and, hence, reduced the throughput of the network. ### Case Study 5

Figure 8 shows the results of Case Study 5 with \(10\times 10\) grids, 1250 nodes. The network structure (Figure 8a) shows 100 grids, with the selected cluster heads marked in numbers and connected by a black line. The results of the performance metrics show that with 1250 nodes, the packets sent to the BS (Figure 8b) in the PSOGA achieved improvements of 333% and 45.83%, respectively, as compared to LEACH and PSO.