# Enhancing Route Guidance with Integrated V2X Communication and Transportation Systems: A Review
## 4 V2X Communication Architecture
* Cooperative Awareness: It uses applications for inter-vehicle communications, including emergency vehicle warnings and emergency electronic brake lights to improve road safety [84; 85]. * Cooperative Sensing: If a collision is unavoidable and imminent, the involved vehicles exchange relevant sensor and safety actuator, e.g., raw sensor data and anti-lock braking system data, to reduce the crash severity, and warning messages are broadcasted to all vehicles in the surrounding area. The vehicles may optionally share the messages with the RSUs, which further relay them to more distant vehicles [86]. * Cooperative maneuvers: In performing traffic mergers and lane change operations, the danger of crashes can be decreased by cooperatively exchanging information about the nearby traffic and movement trajectory information, for instance, lane changing, platooning, and cooperative intersection control [86]. * Vulnerable Road User warnings: Alert vulnerable road users (pedestrians, bikers, and motorcyclists) with hand-held devices, such as smartphones, of an approaching vehicle and vice versa [86]. * Traffic Efficiency: Applications for traffic efficiency, such as signal phases and timing and green light optimal speed advisory, are designed to promote coordination and control of traffic, improve traffic flow, and lessen the environmental effects of traffic congestion [86]. * Local and Internet-based infotainment services: Infotainment programs give users access to data that improve passenger convenience and enable international internet services. When location-based services (LBSs) like parking management and electronic toll collection notifications are possible due to vehicular communication, the subclass of cooperative local services applications makes it easier to use various services [87]. Designing an effective RGS requires careful consideration of various factors, including the user's needs and preferences, the available data sources and algorithms, and the hardware and software requirements of the system. Next, we will dive into the specific network communication needs that are crucial for making an RGS both efficient and accurate. * Latency: The system must be able to communicate with various data sources, such as GPS satellites and traffic databases, to obtain accurate information about the current location, traffic conditions, and destinations. Therefore, information-carrying data packets must arrive at the destination in the maximum permissible amount of time after being generated at its source. If there is a delay in the transmission of these information-carrying data packets between the navigation device and the server, for example, the user may receive outdated information about traffic conditions or road closures, leading them to take sub-optimal routes [88]. * Network reliability: The maximum allowed packet loss rate at the application layer. A packet is deemed lost if it is not received by its intended destination within the maximum permitted end-to-end delay. In RGSs, the network reliability can be impacted by a range of factors, including network congestion, signal interference, and hardware failures. For example, if the communication network experiences a disruption or outage, data packets may not be transmitted between system components, leading to inaccurate or incomplete guidance information [86; 88]. * Size of messages: The size of the messages exchanged is crucial when sending multicast or broadcast messages to nearby vehicles. It can impact how quickly and efficiently data are transmitted, which in turn affects the accuracy and reliability of the guidance provided to vehicles' drivers [86; 88]. * Frequency: The bare minimum bit rate needed for the application to run correctly is also a crucial factor. The frequency used can impact the range and strength of the signal, which can in turn impact the reliability and speed of data transmission.