# Enhancing Route Guidance with Integrated V2X Communication and Transportation Systems: A Review
## 6 Proposed Communication Network Architecture for RGS
Vehicles share status updates such as their location, speed, and requests for optimal routes using V2V communication, while also transmitting these data to a central TMC. The TMC collects and processes these data, along with information from additional sources like traffic cameras and sensors, to develop a comprehensive view of traffic conditions. The TMC then calculates the optimal routes for vehicles by incorporating real-time and predictive models. This route guidance is sent back to the vehicles, which accordingly adjust their navigation systems (see Figure 7). The centralized model offers enhanced route optimization through complex calculations by the TMC, leading to more accurate and efficient route recommendations. It provides comprehensive traffic management by integrating data from traffic cameras, sensors, and vehicles, improving traffic flow and coordination. The TMC's centralized control facilitates coordinated decision making among vehicles, reducing congestion and ensuring effective real-time updates. Additionally, the system is scalable, allowing for upgrades and expansion to manage growing traffic volumes. However, the primary drawback is the centralized bottleneck, where the TMC is a single point of failure, potentially compromising system performance if it encounters issues. High  
Figure 6: Scenario 2: Decentralized V2I network flow chart. infrastructure costs are involved in setting up and maintaining the TMC and data collection systems. The model may also introduce latency in route updates due to the time needed for data transmission to and from the TMC. Network dependency on reliable communication can lead to suboptimal routing if disruptions happen, and there are concerns about data privacy when using centralized data collection. V2V to Centralized Unit is often better-suited for environments where there is a need for a flexible, adaptive system that can continue to operate effectively even if the central unit is temporarily unavailable. Figure 8 shows the flow chart for the Hybrid V2V-Centralized Network architecture. This architecture leverages the centralized processing power of the TMC while utilizing RSUs for localized data collection and distribution. This scenario offers several advantages, such as comprehensive data integration from multiple RSUs and infrastructure sensors, which provides an accurate and broad view of traffic conditions. Its centralized processing capabilities allow for advanced route optimization, enhancing route accuracy and overall traffic efficiency. Implementing centralized control, we can achieve better coordination of traffic flow, which not only reduces congestion but also enables timely and well-coordinated route updates for drivers. The system's scalability also allows for the expansion of RSU networks in addition to the enhancement of the central unit, making it well suited to accommodate increasing traffic volumes. However, the model also has its disadvantages, such as the risk of a centralized bottleneck; a failure in the central unit could disrupt the entire system. Additionally, there are high infrastructure costs and potential latency issues due to data transmission between RSUs and the central unit, which require robust communication network performance. Furthermore, the system's heavy reliance on the stability of communication networks presents a significant challenge. Centralized data collection also raises privacy concerns, as personal vehicle information is processed by a single entity. In areas with robust infrastructure support, V2I communication with a centralized unit is preferable, as it can provide more optimized route guidance across a wider area. Figure 10 illustrates the flow chart for the centralized network approach in the V2I communication architecture. Clearly, the centralized VANET network facilitates the communication from vehicles to a centralized unit while employing a multi-tiered vehicle network architecture that incorporates various wireless access technologies.