## 5 Experiments and Results
### Density, Mobility and Shape Concerns  
So far, the presentation and evaluation of F&C had been considered a disk-shaped network with homogeneous density and no mobility. Consequently, various questions immediately arise: What would happen if the density were not homogeneous? What would happen if the shape of the network were irregular? Would the protocol still operate in mobile environments? Table 6 shows the answers to these questions. This table shows the percentage of signaling packets used by F&C operating under ideal and non-ideal conditions versus the number of packets generated by traditional flooding. As for  
Figure 9: Comparison of F&C with different \(d\). (**a**) Signaling overhead; (**b**) Resource discovery delay.  
the shape of the network, we used the irregular shape shown in Figure 11a. For the density experiment, we used a disk-shaped network divided into two halves: the right half had higher node density (i.e., 300 nodes), whereas the left half had lower node density (i.e., 200 nodes). This node arrangement was selected, so all nodes remained connected even in the network's left half. Finally, for the mobility experiment, nodes moved at 1 m/s using the random-waypoint mobility model. In all ideal and non-ideal experiments, the network area and the number of nodes were kept constant, and nodes estimated their repeal-flooding boundary using the first five resource searches only. The experiments consisted again in computing the overall signaling overhead of one node seeking a route to the other 499 nodes, and the results are shown as the percentage of signaling packets generated by traditional flooding that needed 250,000 packets (i.e., 500 \(\times\) 500).  
Figure 11: F&C: Disk and irregular network shape. (**a**) Irregular Shape; (**b**) Disk Shape.  
Figure 10: F&C: Signaling packets for different repeal-flooding boundary values. (**a**) Using optmized repeal-flooding boundary; (**b**) After 2 resource discovery searches; (**c**) After 5 resource discovery searches; (**d**) After 10 resource discovery searches.  
The results in Figure 12 and Table 6 show that even if F&C always achieves its best performance when it operates under ideal network conditions. The performance obtained under non-ideal conditions is not very different from ideal conditions and was 25 to 40 percent better than traditional flooding in all non-ideal scenarios. The irregular-shaped experiment showed that nodes estimated a non-optimized diameter of the network due to the non-disk shape. In turn, this produced an erroneous estimate of the repeal-flooding boundary. However, the final result shows that the signaling overhead was 7 percent higher than the signaling overhead obtained under ideal conditions. As for the density experiment, F&C performance depended on node density around the source node. Let us keep in mind that F&C achieved its best performance when the target node was closer to the source, so when node density around the source node was higher than the average density, F&C achieved better results than when it operated under homogeneous density conditions. An opposite trade-off took place when fewer nodes surrounded the source node. As for mobility, results show that more important than how fast nodes moved is when was the last time that nodes updated their repeal-flooding boundary. As can be observed in the table and in the figure, as long as there is a fresh estimate of the repeal-flooding boundary (i.e., after 60 s), there is little performance degradation. Even after 10 min of the last repeal-flooding boundary estimate, F&C performance remained better than traditional flooding. In summary, even if there is performance degradation, the results in Table 6 and Figure 12 show F&C as a robust and reliable protocol under a diverse array of network conditions.