Vehicle Ranging Protocol for Centimeter-Level Positioning
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Solution Overview
Problem
Current GPS location determination in vehicle-to-vehicle communications provides accuracy of only 2-3 meters, which is inadequate for applications like collision avoidance and autonomous driving, and existing ranging methods face challenges such as high mobility of vehicles, time offsets, half-duplex communication constraints, and the near-far effect, leading to inaccurate position estimation.
Innovation Solution
An efficient ranging protocol is developed that concentrates ranging signals within a very short period, typically 1-4 milliseconds, using multiple RF antennas and pseudo-randomly chosen symbols to minimize interference and account for clock offsets, allowing for centimeter-level accurate vehicle positioning by combining ranging measurements with GPS data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS location determination is used in vehicle-to-vehicle communications, then vehicle positioning can be provided, but the accuracy is only 2-3 meters which is inadequate for collision avoidance and autonomous driving
Solution Approach 1:
The patent combines GPS location determination with wireless ranging measurements to achieve centimeter-level positioning accuracy. The system merges satellite-based GPS data with direct vehicle-to-vehicle distance measurements to overcome the limitations of GPS alone and provide sufficient accuracy for autonomous driving applications.
Solution Approach 2:
The patent introduces wireless ranging signals as an intermediary measurement mechanism between vehicles. Instead of relying solely on GPS satellites, the system uses direct radio frequency measurements between vehicles to determine relative positions with higher precision, acting as an intermediary that bridges the gap between GPS capability and autonomous driving requirements.
2Measurement precision
If ranging signals are transmitted frequently to maintain accurate positioning, then positioning accuracy can be improved, but the number of transmitted signals increases causing interference and resource consumption
Solution Approach 1:
The patent performs preliminary actions by having vehicles exchange ranging assistance information in advance, including predicted position data and ranging parameters. This preparation allows vehicles to perform accurate ranging measurements with fewer actual ranging signal transmissions, as the preliminary information exchange establishes a foundation for efficient subsequent measurements.
Solution Approach 2:
The patent implements periodic ranging measurements at optimized intervals rather than continuous transmissions. By determining appropriate measurement periods based on vehicle mobility and positioning requirements, the system maintains sufficient positioning accuracy while significantly reducing the total number of ranging signals transmitted compared to continuous measurement approaches.
3Measurement precision
If ranging measurements are performed continuously to track high mobility vehicles, then positioning accuracy can be maintained, but the time offsets and half-duplex communication constraints cause inaccuracies
Solution Approach 1:
The patent implements feedback mechanisms where vehicles exchange information about their ranging measurements, time offsets, and position estimates. This feedback loop allows vehicles to compensate for time offset errors and half-duplex communication constraints by adjusting their measurements based on received information from other vehicles, thereby maintaining accurate positioning despite these challenges.
Solution Approach 2:
The patent performs preliminary exchange of time synchronization information and ranging parameters before actual ranging measurements. This preliminary action allows vehicles to compensate for time offsets during the measurement process, reducing timing errors without requiring continuous high-frequency measurements that would exacerbate half-duplex constraints.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves vehicle location accuracy to centimeter levels, enhancing collision avoidance and autonomous driving capabilities while reducing the number of transmitted ranging signals and mitigating the effects of high vehicle mobility and communication constraints.
Implementation Method 1
measuring a time of flight (ToF) of a ranging signal
Implementation Method 2
transmitting a ranging signal with the sequence ID on each of the randomly selected symbols
Data Source
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AI summary
A method for ranging includes randomly selecting a symbol in each of at least two successive sub-cycles of a ranging cycle, transmitting symbol IDs corresponding to the randomly selected symbols and a sequence ID, and transmitting a ranging signal with the sequence ID on each of the randomly selected symbols.