## 5 Performance Evaluations
### Scenario Characteristics for Mobility Handling Simulations  
In the simulations, the sensor nodes are uniformly deployed in a rectangular deployment area of 1,800 \(\times\) 1,800 \(m^{2}\) where we have 3 sinks. Every sensor node has a transmission range of 250 \(m\). We use Random Waypoint movement model to simulate sensor node mobility. The speed of the mobile nodes varies from low mobility (_i.e._, 4-5 km/h for walking humans) to high mobility (e.g., 40-60 km/h for UAVs [36]) scenarios. A simulation run lasts 100 simulation seconds. For a given simulation run, results are averaged over all the queries sent during the simulation. The averaged values are calculated over 10 different deployments with a fixed number of sensor nodes. For each deployment, we randomly select 5 different center points for disjoint target regions which are circular areas. Assuming to divide the deployment area into 4 sub-rectangles from the center, one of the target region is at the middle of the network and the other four are in one of the sub-rectangles. Figure 10 illustrates an example simulation topology with convex hulls of sinks and target regions. The target regions are created in a way that they cover all the directions in the deployment area. The simulation parameters are given in Table 1. Although IEEE 802.15.4 is a standard developed to meet the needs for low-power and low-cost wireless communication, we prefer to use the IEEE 802.11 standard in our simulations to be comparable with previous works. A comparative performance study of IEEE 802.15.4 and IEEE 802.11 can be found in [37]. Another reason of using IEEE 802.11 in the simulations is that it achieves a higher packet delivery ratio since it uses a handshaking mechanism before sending packets. IEEE 802.11 is chosen to minimize the effect of MAC layer on the performance of our routing protocol.  
We compare the performance of our geocasting protocol when we have only global updates started by sinks periodically and local updates triggered by mobile sensors. Global updates are sent from sinks with a frequency varying from 3 to 25 seconds. In simulations with only global updates, the queries are sent 100 \(ms\) before the next global update starts. In simulations with construction of geocast structure followed by only local updates, the queries are sent every 10 seconds. As described in Section 4, mobile nodes send beacon packets periodically having a frequency based on the speed of the node and the mobile node beacon parameter, which varies.  
\begin{table}
\begin{tabular}{|l|l|} \hline Simulation time & 100 \(s\) \\ \hline Simulation area & 1,800 \(\times\) 1,800 \(m^{2}\) \\ \hline MAC protocol & IEEE 802.11 DCF \\ \hline Transmission range & 250 \(m\) \\ \hline Number of sinks & 3 \\ \hline Number of sensor nodes & 60 to 360 \\ \hline Number of mobile nodes & 10 to 50 \\ \hline Mobile node speed & 1 to 17 \(m/s\) (4 to 60 \(km/h\)) \\ \hline Mobility model & Random Waypoint \\ \hline Global update frequency, \(f\) & 3 \(s\) to 25 \(s\) \\ \hline Mobile node beacon parameter, \(k\) & 0.05, 0.10, 0.20 \\ \hline Target region & Circle, radius 250 \(m\) \\ \hline Target region selection & 5 random center points \\ \hline Query sending frequency & 10 \(s\) for local update simulations \\  & 100 \(ms\) before global updates \\ \hline \end{tabular}
\end{table}
Table 1: Simulation Parameters.  
Figure 10: An example topology with coverage areas of sinks and target regions.