## 6 Network Simulation and Results
### Results
#### 6.2.1 Shortest-Path RREQ Forwarding  
The first observation that can be highlighted from the shortest-path RREQ forwarding results is that the use of \"standard\" jitter does not have an significant impact on the RREQ flooding performance, when compared with the no-jitter setting; neither in terms of collisions, control overhead or data path length. Differences can be observed, in contrast, between window jitter and \"standard\" and no jitter.  
Figure 15(a) shows the number of collisions with a different density of routers. When using no jitter, the highest number of collisions, slightly higher than with \"standard\" jitter, occurs. This is because adjacent routers are more likely to retransmit received RREQs at the same time. Window jitter (50-100 ms, 100-150 ms) yields significantly fewer collisions, especially in high-density scenarios. This is because the use of the window jitter enables forwarding routers to reduce the number of transmissions (_i.e._, overhead) by reducing the cases of delay inversion, as shown in Figure 15(b).  
Regarding the evolution of route discovery delay (_i.e._, the time between RREQ transmission and reception of the corresponding RREP) with respect to the network density in the shortest-path RREQ  
Figure 16: Simulation results of shortest-path RREQ forwarding. (**a**) Number of collisions; (**b**) Average overhead.  
forwarding strategy, depicted in Figure 17b, it is interesting to observe that the impact of the different types of jitter is different for low-density and high-density networks. The average route discovery delay for each type jitter is highly correlated with the mean of the random jitter variable: settings with higher jitter means exhibit higher average delays in the route discovery processes. For denser networks, in contrast, window jitter presents better performance in terms of route delivery delay than \"standard\" jitter, regardless of the mean value of the jitter random variable. The use of \"standard\" jitter (or the immediate retransmission of RREQ messages, without jitter) in dense networks leads to an explosion of control traffic when the shortest-path RREQ forwarding strategy is used. This control traffic explosion can be indirectly observed in the evolution of the number of packet collisions in the network, as depicted in Figure 16a, and the data packet delivery ratio, as depicted in Figure 17a. As the control traffic load grows beyond the network capacity, a more significant fraction of transmitted data packets cannot be correctly delivered, even when routes are available, due to the increasing number of packet collisions. By reducing substantially the probability of delay inversion, the use of window jitter distributions improves the quality of the selected routes (see Figure 17c) and allows one to reduce the number of RREPs sent in response to an RREQ. This alleviates the control traffic load of the network and decreases the number of packet collisions, therefore significantly reducing the average delay for route discovery processes.  
Figure 17: Simulation results of shortest-path RREQ forwarding. (**a**) Data packet delivery ratio; (**b**) The average route discovery delay; (**c**) Average path length.