## 4 Methodology
### TMR Routing Protocol
Additionally, it may impose computation load on nodes. However, TMR does not need to use the GPS and, therefore, the overload in terms of packet size is minimized and this accordingly reduces the traffic load in the network. Several pieces of research do not consider computing energy requirements in terms of energy consumption. With limited resource devices, it could be time and energy consuming. As an exemplification, EGSR considered that each node has sufficient computation resources, which is not always the case. On the other hand, TMR is a reactive routing algorithm and this minimizes the energy consumption as the routes are optimized on-demand. Regarding scalability, road segments in TMR are limited by the average RTT threshold between OBU nodes and RSU nodes. This in turn will reduce the latency and enhance the data throughput. In EGSR, the road connecting two adjacent intersections is considered as the road segment. ### Routing Protocol Time Complexity

To understand the time complexity of the route discovery phase, we consider three different scenarios as depicted in Figure 36. In this regard, we consider that there is \(n\) number of intermediate nodes in the network. According to Scenario (a), all the intermediate nodes are receiving the RREQ packet simultaneously and all of them broadcast it towards the destination D in the worst-case scenario where the route to D is not available in any node. Therefore, the order of RREQ broadcasting sent by source node S is \(O(n)\). Furthermore, each intermediate node may rebroadcast RREQ and all other nodes receive that. Therefore, each node will receive RREQ one time from node S and \(n\) times from other nodes. Therefore, the entire network deals with the time complexity of \(O(n^{2})\) on receiving RREQ. In contrast with Scenario (a), in Scenario (b), the intermediate nodes are arranged serially. Each node receives the RREQ once from the previous node and once from the next node in the worst-case scenario. Therefore, the order of RREQ flooding is \(O(2n)\). As to Scenario (c), if all the intermediate nodes are included in a route, then the time complexity of RREQ remains \(O(n)\). Each node will receive an RREQ \(n\) times from other nodes. Therefore, the entire network deals with the time complexity of \(O(n^{2})\) on receiving RREQ. In conclusion, the number of times that a network must go through the route discovery phase depends on the network configuration and topology. This is the reason we need to study the routing protocols via simulation. Figure 36: Scenarios of time-complexity networks. \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Characteristics** & **TMR** & **EGSR [22]** & **QMR [16]** & **FF-AOMDV [11]** & **ISR [24]** & **AOMDV** \\ \hline Clock Synchronization & Yes & Yes & No & No & No & No \\ \hline GPS & No & Yes, required at is geographic aware protocol & Yes, acquire position & NO & Yes, required for positioning the head node & No \\ \hline Energy optimization & No & No & Yes & Yes & No & No \\ \hline Scalability approach & Road segmentation & Road segmentation & No & No & Road segmentation & No \\ \hline Routing Discovery & Reactive protocol & Proactive protocol, based on \(t_{ant}\) & Hybrid protocol, Q-learning with variable \(\alpha\) and \(\gamma\) & Reactive protocol & Proactive protocol & Reactive protocol \\ \hline RTT & Yes & NO & NO & NO & NO & NO \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Routing protocol characteristics comparison. ## 7 Conclusions

In this paper, we propose a Multipath Routing Protocol called TMR that makes use of the round trip time (RTT) to perform packet transmission tasks to the destination node in VANETs. The main idea in the TMR routing protocol is the implementation of centralized network intelligence in one component of the network to reduce the time taken while maintaining the consensus between source and destination for efficient packet data transmission.