# Optimization of Submodularity and BBO-Based Routing Protocol for Wireless Sensor Deployment
## 4 Experimental Verification
### Results and Analyses
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Mutual Information**} & \multicolumn{4}{c}{**Sensor Number**} \\ \cline{2-5}  & **Greedy** & **pSPLIE** & **IHACA** & **IHACA-COpSPIEL** \\ \hline
0.14 & 5 & 6 & 7 & 6 \\
0.15 & 6 & 8 & 8 & 7 \\
0.16 & 7 & 10 & 10 & 8 \\
0.17 & 10 & 13 & 12 & 10 \\
0.18 & 12 & 14 & 13 & 12 \\
0.19 & 17 & 25 & 25 & 20 \\
0.20 & 25 & 30 & 30 & 28 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of sensor number for the four algorithms. Figure 1: Sensor deployments of the four algorithms. Figure 2: Cost performance and mutual information of the four algorithms. Comparison of the lifecycle and average energy  
The life cycle refers to the time from which the wireless sensor starts to work until the death of the first node. Figure 3 shows the comparison results of the life cycle of the sensor nodes selected by the routing protocol based on the BBO algorithm for the greedy algorithm, the pSPIEL algorithm, the IHACA algorithm, and the IHACA-COpSPIEL algorithm proposed in this paper. It shows from Figure 3 that the first dead node under the greedy algorithm appears in round 1368, the first dead node in the IHACA algorithm appears in round 1272, and the first dead node of the IHACA-COpSPIEL algorithm proposed in this paper appears in round 1681, which indicates that the wireless sensors deployed in the IHACA-COpSPIEL algorithm have a longer life cycle. The reason for this is that the communication distance of the wireless sensors deployed by the IHACA-COpSPIEL algorithm is the shortest, which reduces the energy consumption of transmission. Figure 4 shows a comparison of the remaining energy percentages of data transmission after the sensors are deployed in each of the four algorithms. The IHACA-COpSPIEL algorithm has a higher percentage of remaining energy per round than the greedy, pSPIEL, and IHACA algorithms. Therefore, the overall energy consumption of the proposed algorithm is lower than any of the other three algorithms. As the number of simulation rounds increases, Figures 5 and 6 show both the deaths of nodes by using the LEACH routing protocol and the BBO routing protocol, respectively, and the network energy consumption results by using the LEACH routing protocol and the BBO routing protocol, respectively, to deploy sensors in the IHACA-COpSPIEL algorithm. As is seen from Figure 5, under the LEACH  
Figure 4: Percentage of remaining energy in the four algorithms. Figure 3: Comparison of the percentage of dead nodes in the four algorithms. protocol, the first node died in round 1435 and the last node died in round 1584, and under the BBO routing protocol, the first node died in round 1659 and all nodes died in round 2071. The network survival time is longer than the former. As is seen from Figure 6 that the remaining energy under the routing protocol based on the BBO algorithm has always been more than that under the LEACH protocol. This is because the routing protocol based on the BBO algorithm fully takes the cluster into account. The distance between the nodes and the cluster heads, the distance between the cluster heads and the cluster heads, and the total energy consumption effectively balances the network load. Hence the life of the entire wireless sensor network is significantly extended.