# Efficient Mobile Sink Routing in Wireless Sensor Networks Using Bipartite Graphs
## 6 Simulation Results
From Figure 6, it can be seen that the proposed mobility obtained high and stable results for all network sizes under the speed of 10 and 15 m/s of the mobile sink because the mobile sink is moving at moderate speeds, which reduced the number of updates and the changes that may occur to the routing paths. Additionally, static sensor nodes will have a reasonable amount of time to communicate with the mobile sink and deliver data successfully. The performance of the network consisting of 51 nodes was the best and the most stable in all cases because the length of the routing paths was moderate; as a result, the packet did not have to go through many hops to be delivered. The length of the movement path adopted by the mobile sink was moderate; as a result, static sensor nodes did not need to update their routing tables frequently, and higher performance results were thus achieved. For all other cases of mobile sink speeds, the performance of different network sizes was almost stable but was lower than that of 51 nodes' networks. This was for one of two reasons. First, the mobile sink's speed may not be suitable for the network size. To put it another way, high speeds may not be suitable for small networks, and low speeds may not be suitable for large networks because the network may be congested, and packets will be dropped. Second, for large network routing and low speeds, the routing paths may be very long, which might cause congestion in some parts of the network and result in a dropping packet. On the contrary, small networks operating under high speeds of the mobile sink packet may be dropped because of frequent changes in the topology and the routing paths, which results in consuming a large amount of the bandwidth to update the paths, which affects the network performance and increases the number of dropped packets. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Speed**} & \multicolumn{4}{c}{**Network Size**} \\ \cline{2-5}  & **26 Nodes** & **51 Nodes** & **76 Nodes** & **101 Nodes** \\ \hline
5 & 95.20 & 98.52 & 99.81 & 95.25 \\
10 & 91.63 & 98.96 & 99.81 & 99.57 \\
15 & 88.70 & 99.24 & 99.02 & 99.25 \\
20 & 90.63 & 94.83 & 99.25 & 98.88 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Packet Delivery Ratio. Figure 6: Network throughput. Additionally, many packets may go through unnecessary hops to be delivered, and the time to live timer or the counter of the packet thereby expires, which results in the packets getting dropped. Table 4 summarizes the results obtained for the network throughput and compares the results achieved by each network using different mobile sink speeds. From Table 4, it is clear that the network consisting of 51 nodes outperformed all other networks under all the different speeds used for the mobile sink. Consequently, for all other networks, using the different speeds of the mobile sink may have caused frequent updates to the routing paths, or the movement path adopted by the mobile sink was very long. As a result, static sensor nodes may have suffered from buffer overflow, and packets were dropped, affecting the performance of these networks.