## 4 Simulation Results
### Comparison between MMMR and Other Routing Protocols
Moreover, much of the lost packets traveled through several hops before being dropped. GBSR-B obtains the highest delay in the low density scenario (see Figure 4(a)), due to the high amount of time that packets spend in the local buffer. This does not happen so frequently in the medium density scenario, due to the presence of a higher number of neighbors, which allows for a faster selection of an optimal next forwarding hop. The same happens with MMMR, but with better results, since it also includes the building-aware capability and the improvement of the forwarding decision with the use of the four metrics described in the previous section. In the case of AODV in  
Figure 5: The average end-to-end packet delay in (**a**) a low density scenario (60 nodes) and (**b**) a medium density scenario (120 nodes) are presented, comparing the protocols, AODV, GPSR, I-GPSR, GBSR-B and MMMR (CI 95%). the low density scenario (see Figure 4(a)), packets that needed a recovery process (after route breakage, new RREQ/RREP (Route Request/Route Reply) messages to find a new end-to-end path are exchanged) suffered a high loss probability and often did not arrive at the destination. Consequently, AODV obtains a low packet delay computed only from packets successfully delivered. In contrast, in the medium density scenario (see Figure 4(b)), packets that used the recovery process had a higher probability to arrive at the destination, due to the presence of a high number of neighbors, which offers more options to forward the packets. However, those packets suffered a higher packet delay (Figure 4(b)). Finally, we can see that I-GPSR obtains a slightly lower delay in the low density scenario compared to MMMR, due to the high number of packet losses that used a long path, so that they were not considered in the computation of the average delay. In the medium density scenario, I-GPSR obtains the highest delay compared to the other protocols, due to the process of the next forwarding selection, which penalizes vehicles stopped momentarily in crossroads, although they could be good forwarding candidates. Regarding the average number of hops, depicted in Figure 6, the results are very much related to the scheme to choose the next forwarding node used by each routing protocol. We can see that GBSR-B (fourth column) delivers more packets successfully after using more hops compared to GPSR (second column). This is mainly due to the building-aware scheme of GBSR-B, which refrains from choosing vehicles behind buildings, which reduces the losses (see Figure 4), although more hops are used. In AODV (first column), we can see that in the medium density scenario (Figure 5(b)), there are paths with a lower number of hops compared to the low density scenario (Figure 5(a)), since shorter paths could be formed among more nodes to be chosen. However, AODV spends more time in establishing the full path, obtaining, therefore, a high delay (see Figure 4(b)). Notice that our MMMR presents the highest number of hops in the low density scenario (Figure 5(a)). The reason is that MMMR not only uses distance as the metric to choose the next forwarding nodes; MMMR also uses the trajectory, density and available bandwidth that longer number of hops will use. In the medium density scenario (Figure 5(b)), a lower  
Figure 6: The average number of hops to the destination in (**a**) a low density scenario (60 nodes) and (**b**) a medium density scenario (120 nodes) are presented, comparing the protocols, AODV, GPSR, I-GPSR, GBSR-B and MMMR (CI 95%). number of hops were needed, since there are more neighbors to choose a proper next hop according to the four-metric algorithm. Notice that our proposal is mainly focused on VANETs, and we try to increase the number of packets that arrive at the destination. With our proposal, packets sent from farther distances, which need more hops to get to the destination, can reach the destination more frequently, thus increasing the average number of hops.