Vehicle On-Board Unit Dynamic Congestion Control
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Solution Overview
Problem
The DSRC system experiences congestion in high-traffic areas due to the hidden terminal problem, leading to increased frame collisions and decreased network performance, with existing solutions lacking a method to determine congestion conditions effectively.
Innovation Solution
A vehicle on-board unit equipped with a short range wireless broadcasting section, a vehicle identifier receiving section, and a communication congestion determining section to broadcast a host vehicle identifier, receive neighboring vehicle identifiers, and determine congestion conditions within a prescribed communication region, informing users of the DSRC system capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of vehicles transmitting DSRC signals within the communication region increases, then more vehicles can communicate and share information, but localized congestion in the DSRC system increases and network performance decreases
Solution Approach 1:
The patent implements a feedback mechanism where the on-board unit continuously monitors the communication environment by receiving vehicle identifiers from neighboring vehicles within a prescribed time period. Based on this feedback information about the number of transmitting vehicles, the system dynamically adjusts its transmission strategy to maintain network performance while allowing high vehicle density.
Solution Approach 2:
The system dynamically changes its operation mode based on real-time congestion conditions. When congestion is detected (high number of neighboring vehicles), the system adjusts by scaling back broadcast power and update rates. When congestion is low, the system operates at full capability, allowing maximum information exchange.
2Reliability
If vehicles broadcast identifiers at high power and high update rates, then communication reliability improves, but channel congestion increases and frame collisions increase
Solution Approach 1:
The patent changes the parameters of wireless transmission dynamically based on congestion conditions. Specifically, it adjusts broadcast power level and update rate (frequency) according to the monitored number of neighboring vehicles. This parameter adaptation allows the system to maintain communication reliability when needed while reducing frame collisions during high-density scenarios.
3Loss of information
If the update rate of Common Message Set broadcasts is increased, then information freshness improves, but system congestion increases
Solution Approach 1:
The system uses periodic broadcasting of Common Message Sets but dynamically adjusts the period (update rate) based on congestion conditions. When congestion is low, updates occur frequently to maintain information freshness. When congestion is high, the update rate is reduced to minimize channel usage while still providing timely safety information.
Data Source
AI summary
A vehicle on-board unit comprises a short range wireless broadcasting section, a vehicle identifier receiving section, a vehicle identifier counting section and a communication congestion determining section. The short range wireless broadcasting section is configured to broadcast a host vehicle identifier of a host vehicle equipped with the vehicle on-board unit. The vehicle identifier receiving section is configured to receive neighboring vehicle identifiers relating to neighboring vehicles located within a prescribed communication region around the host vehicle. The vehicle identifier counting section is configured to determine a number of the neighboring vehicle identifiers received by the vehicle identifier receiving section within a prescribed period of time. The communication congestion determining section is configured to determine a congestion condition of short range wireless communications within the prescribed communication region based on the number of the neighboring vehicle identifiers determined in the vehicle identifier counting section.