V2X CACC String Management for Traffic Flow
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Solution Overview
Problem
Cooperative Adaptive Cruise Control (CACC) services can negatively impact lane capacity and induce traffic congestion, necessitating a method to efficiently manage CACC streams and maintain traffic flow.
Innovation Solution
A Vehicle to Everything (V2X) communication apparatus with a CACC dedicated facility layer entity processes received messages to recognize CACC strings, estimate their length, and restrict them, thereby reducing unnecessary processing and alleviating traffic congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CACC service is provided to improve traffic safety and fuel consumption, then safety and fuel efficiency are improved, but lane capacity decreases and traffic congestion is induced
Solution Approach 1:
The patent changes the parameter of message transmission frequency by introducing discontinuous transmission based on event triggers. Instead of continuous periodic transmission, messages are transmitted only when specific events occur (lane changes, acceleration, deceleration), thereby reducing overall message volume while maintaining safety-critical communication.
Solution Approach 2:
The patent implements periodic message transmission with variable periods. The transmission frequency is adjusted dynamically based on driving conditions and CACC string length, using longer periods for stable conditions and shorter periods when events occur, thus balancing safety requirements with traffic flow efficiency.
2Productivity
If CACC string length is increased to improve traffic efficiency, then fuel consumption decreases, but traffic congestion is induced
Solution Approach 1:
The patent implements feedback mechanisms where vehicles monitor CACC string length and adjust transmission behavior accordingly. When the string length exceeds a threshold, the system triggers event-based transmission to reduce message volume, preventing congestion while maintaining the benefits of longer CACC strings.
Solution Approach 2:
The patent makes the message transmission frequency dynamic rather than static. The transmission rate adapts based on real-time conditions including CACC string length, driving events, and traffic conditions, allowing the system to optimize between fuel efficiency and congestion prevention.
3Speed
If V2X message transmission frequency is increased to improve CACC service quality, then response time is reduced, but unnecessary processing increases and delay time increases
Solution Approach 1:
The patent extracts only the essential safety-critical information for transmission, omitting redundant data. By selectively transmitting only necessary parameters based on event triggers, the system reduces message volume and processing requirements while maintaining fast response times for critical events.
Solution Approach 2:
The patent changes the transmission parameter from continuous periodic messages to event-triggered messages. This parameter change reduces the total number of transmissions while ensuring that critical events are communicated immediately, thereby reducing both processing overhead and overall delay time.
Data Source
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AI summary
A method for receiving a V2X message by a V2X communication apparatus is disclosed. The method for receiving a V2X message may include receiving a V2V message including Cooperative Adaptive Cruise Control (CACC) information from at least one CACC vehicle, and the CACC information includes CACC String ID (CSID) information for identifying a CACC string to which the CACC vehicle is belonged and string length management information used for managing a string length of the CACC string, obtaining the CSID information and the string length management information from the V2V message; and setting a value of the string length management information of the subject vehicle based on the CSID information and the string length management information. Here, the string length management information may include at least one of Order In String (OIS) information indicating a current order of the CACC vehicle in the CACC string or CACC String Length (CSL) information indicating a length of the CASS string.