## 3 Results and Discussions
### Beacon/Hello Interval
This indicates that a higher frequency of Beacon messages is essential for improving PDR. In contrast, AODV's PDR exhibits a different behavior, with less frequent Hello packets resulting in a higher PDR in highway scenarios but a decrease in PDR in city environments. For GPSR, the decline in PDR with longer Beacon intervals is aligned with the protocol's dependency on frequent neighbor updates for effective packet forwarding. GPSR relies on its greedy forwarding mechanism, which requires up-to-date information about the positions of neighboring nodes. As the Beacon interval increases, the information about neighboring nodes becomes outdated, which reduces the protocol's ability to forward packets efficiently and increases the likelihood of packet drops. This is particularly critical in high-mobility highway environments, where the network topology changes rapidly, and real-time updates are essential. The same effect is seen in city environments, although the impact is slightly mitigated by the higher node density, which offers more opportunities for successful forwarding. Nonetheless, shorter Beacon intervals enhance the protocol's ability to find and maintain valid routes, thereby increasing the probability of packet delivery and yielding a higher PDR. The PDR trends observed in AODV are different. In highway environments, where node mobility is high, less frequent Hello packets lead to a higher PDR. This behavior can be explained by the reduction in protocol overhead. AODV uses Hello packets primarily to maintain its routing table, and sending these packets too frequently increases the network's overhead, leading to collisions and delays in routing information dissemination. By decreasing the frequency of Hello packets, the protocol reduces congestion in the network, allowing for smoother data transmission and improved packet delivery. In contrast, in city environments, where the network is denser, and collisions are more frequent, AODV benefits from more frequent Hello packets, which keep routing tables updated. This ensures that nodes have fresh routing information, reducing packet loss due to outdated routes and improving PDR. However, the increase in PDR with more frequent Hello packets in the city also contributes to higher overhead,  
Figure 7: Delay comparison between VANET scenarios and. Beacon/Hello Intervals. leading to a more nuanced trade-off between maintaining route freshness and avoiding excessive congestion. The variation in PDR between AODV and GPSR is significant. AODV's PDR changes are relatively minor, with a 1% variation in highway scenarios and 1.5% in city environments. This limited variation suggests that AODV's reliance on Hello packets for route maintenance has a smaller overall impact on packet delivery success. The primary function of Hello packets in AODV is to maintain routing tables rather than directly facilitating data transmission, so the effect of Hello packet frequency on PDR is less pronounced. GPSR, on the other hand, exhibits a much larger variation in PDR, with a 10% change in highway environments and a 15% change in city environments as the Beacon interval increases. This is because GPSR uses Beacons not just for routing updates but as a core part of its packet forwarding mechanism. Hence, the frequency of Beacons directly influences the probability of successful packet delivery, leading to more pronounced changes in PDR. In summary, Figure 8 demonstrates that GPSR is highly sensitive to Beacon interval changes, with PDR improving significantly when Beacon frequency is increased. This highlights the importance of frequent neighbor updates in maintaining high packet delivery rates in both city and highway environments. For AODV, the impact of Hello interval on PDR is more limited, as the protocol's focus on routing table maintenance means that its PDR is less affected by Hello frequency.