# Energy and Distance-Aware Hopping Sensor
## 3 Simulation Results and Analysis  
We have implemented the proposed relocation protocol for hopping sensors using the well-known network simulator OMNeT++ [26; 27] to evaluate its performance. Table 1 describes the environment settings used in the simulation. As shown in Figure 10(a), 285 hopping sensors were randomly distributed in the area of 250 m \(\times\) 150 m to collect the data. As mentioned previously in Section 2.1, we assumed that 15 cluster zones and headers were set appropriately. If there are less than 5 sensor nodes in each cluster zone, it is assumed to be a sensing hole. The hopping sensor employs the IEEE 802.11 model, and the maximum communication radius by jumping is 29 m. Also, it is assumed that the sensors move 1 m by one hopping and are capable of hopping up to 290 times. Note that this is the distance that the hopping sensor can traverse diagonally across a given area. The number of sensing holes is up to 2 as shown in Figure 10(b),c. For example, Figure 10(b) shows a scenario that one sensing hole could occur, since the sensor nodes' energies are abruptly consumed due to continuous data collection in the middle cluster. For this scenario, each sensor in the middle cluster performs data collection with an exponential distribution (average 10 simulation time units), and energy consumption follows a uniform distribution. When less than 5 sensors collecting data in \begin{table}
\begin{tabular}{c c} \hline \hline
**Network Area** & **250 m \(\times\) 150 m** \\ \hline Number of total member sensor nodes scattered & 285 \\ Number of cluster headers & 15 \\ Number of minimum members in each cluster zone & 5 \\ Maximum communication radius by jumping & 29 m \\ Maximum distance moved by one hopping & 1 m \\ Hopping capability per a sensor initially & 290 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The simulation environment. Figure 10: The wireless sensor network environment and examples for when sensing holes occur: (**a**) The hopping sensors are scattered, the cluster zones are configured, and the cluster headers are set up; (**b**) a single sensing hole occurred; and (**c**) two sensing holes occurred. the zone, the cluster header can recognize that a sensing hole is generated, by the periodic HELLO message. In order to simulate the relocation of member sensor nodes, the sensors in the other zones are assumed that there was no data collection. Figure 11 also shows that the yellow color sensor is in a fault state due to an energy depletion after continuous data collection. The movement of the hopping sensor is indicated by a solid line. Most of the hopping sensor relocation protocols studied so far have considered only the shortest path between cluster zones, which is, in reality, very hard to implement in a wireless sensor network. In order to overcome this problem, we have implemented the simulation in a distributed environment. As far as we know, this is definitely the first simulation result in this research area using OMNeT++, which takes into account the distributed environment and all communication system layers similar to the real world. The proposed relocation protocol considers both the distance to the sensing hole and the movability of the nodes. When the weight \(w\) is close to 0, only the distance to the sensing hole is considered, and when the weight \(w\) is close to 1, the residual energy is considered. Previous studies have considered the shortest distance between clusters, but this is only the distance between the clusters and not the actual location of sensor nodes, considering the random selection of member sensors inside the cluster. Therefore, our relocation protocol considering the distance between the sensor nodes has obtained various research results which cannot be compared with the previous researches. As shown in Figure 12, it can be seen that the simulation for recovering the sensing hole is very fast, considering the rearrangement of the hopping sensors with a weight close to zero (i.e., distance only).