## 5 Discussion
In Section 4.4.2, results showed that the average communication cost, all-channel utilization, latency, and PDR of the proposed routing method and Dijkstra tend to increase with the increment of the routing frequency, while those of AODV degrade with the routing frequency. One of the reasons for the preceding observation is that both Dijkstra and proposed routing are used in SDVN, where the routes are computed by the centralized controller, which collects metadata from the vehicular network to compute the routes and control routing accordingly. However, in AODV, routes are computed on demand at the time of routing, such that, when it has little time for routing, i.e., when the routing frequency increases, its performance degrades. The other reason we can think of as the reason for incrementing PDR, etc., with routing frequency for the proposed routing is that we can expect the average network contention to increase with the increment of routing frequency, such that the proposed routing will switch more towards the most stable shortest path selection mode, which can increase latency, cost, and PDR, similar to the increment of the same in a shortest path algorithm such as Dijkstra with routing frequency. In Section 4.4.3, we observed that the communication cost, channel utilization, latency, and PDR of all routing techniques increase with network size. The reason for that increment is the increment in average network link entropy and node density with network size, as the nodes are placed in a fixed-size map. However, the communication cost in an isolated network is non-zero for proposed routing and Dijkstra, as they collect metadata for computing routes at the controller. However, the latency, DSRC utilization, and PDR are zero for all routing techniques in an isolated network (network size of four), since that network must have zero average network link entropy (all nodes are isolated). With the increment in average network link entropy when the network size increases, the average number of hops per route in the network for routing packets increases, which is the reason for the increment in average latency with network size. The communication cost, channel utilization, and latency of distributed routing, such as AODV, are much higher than those of the proposed routing method for large networks due to the amplification of route discovery steps with network size. Furthermore, the PDR of the proposed method is significantly higher than both AODV and Dijkstra for large networks, while both the communication cost and latency of the proposed method are significantly lower than other routing techniques. Thus, for large networks, the proposed routing method yields superior performance to both AODV and Dijkstra. In Section 4.4.4, we observed that the increasing order of communication cost, channel utilization, latency, and PDR for all routing techniques is rural, followed by urban, and then autobahn. The reason for the preceding order is that the average network link entropy varies in the same order due to the effect of both node density and maximum transmission power in each mobility scenario. When the average link entropy increases, the average number of neighbors for a given node also increases. Thus, the increasing order of average neighbors per given node is rural, urban, and autobahn, as explained by their corresponding node density and maximum transmission power values. Furthermore, it was observed that a given parameter for a given routing technique (e.g., latency of the proposed method) may have an increasing or decreasing trend, or no clear variation, with speed among different mobility scenarios. The reason for this could be that when changing the maximum allowable speed for a given mobility scenario, the underlying mobility pattern can be changed among different speeds for the same mobility scenario.