Dynamic SS-TWR to DS-TWR Switching for Sidelink Positioning
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently switching between single-sided (SS) two-way ranging (TWR) and double-sided (DS) TWR procedures for sidelink positioning, particularly due to time gaps between positioning reference signals that can lead to clock drift and reduced positioning accuracy.
Innovation Solution
The proposed solution involves a method where a first UE measures the time difference between the transmission of a first sidelink positioning reference signal (SL-PRS) and the reception of a second SL-PRS to determine if a third SL-PRS should be transmitted, allowing dynamic switching from SS-TWR to DS-TWR based on this measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If SS-TWR procedure is used for sidelink positioning, then the positioning process is simpler and faster, but clock drift occurs due to time gaps between positioning reference signals reducing positioning accuracy
Solution Approach 1:
The patent implements dynamic switching between SS-TWR and DS-TWR procedures based on real-time clock drift detection. The system transitions from a static positioning approach to a dynamic one where the TWR type is selected based on current clock synchronization status, resolving the contradiction between speed and accuracy by adapting to changing conditions.
Solution Approach 2:
The patent changes the operational parameter of the TWR procedure type (SS-TWR vs DS-TWR) based on measured clock drift. When clock drift exceeds a threshold, the system switches to DS-TWR which provides better accuracy, while maintaining SS-TWR for normal operations to preserve speed, thus resolving the accuracy-speed tradeoff.
2Measurement precision
If DS-TWR procedure is used for sidelink positioning, then positioning accuracy is improved by correcting clock drift, but the positioning process becomes more complex and time-consuming
Solution Approach 1:
The system dynamically adjusts the positioning procedure complexity by switching between SS-TWR and DS-TWR based on clock drift conditions. DS-TWR is only activated when necessary (when clock drift exceeds threshold), keeping the system simple during normal operations while providing enhanced accuracy when needed.
Solution Approach 2:
The patent changes the procedure type parameter from SS-TWR to DS-TWR based on clock drift measurements. This conditional parameter change allows the system to maintain low complexity during normal operations (SS-TWR) while enabling high accuracy mode (DS-TWR) only when clock drift compromises positioning precision.
3Measurement precision
If DS-TWR procedure is used for sidelink positioning, then positioning accuracy is improved by correcting clock drift, but the time required for positioning increases
Solution Approach 1:
The system dynamically selects the positioning procedure type based on clock drift conditions, using SS-TWR for quick positioning when clocks are synchronized and DS-TWR for accurate positioning when clock drift is detected. This dynamic adaptation resolves the time-accuracy contradiction by using the appropriate procedure for current conditions.
Solution Approach 2:
The patent changes the operational mode between SS-TWR and DS-TWR based on clock drift threshold comparisons. When clock drift is within acceptable limits, SS-TWR provides fast positioning; when clock drift exceeds the threshold, DS-TWR is activated to provide accurate positioning, thus optimizing the time-accuracy tradeoff.
Data Source
AI summary
Method and apparatus for switching between SS-TWR and DS-TWR. The apparatus reserves resources for transmission of a first SL-PRS in a first time slot. The apparatus transmits, to a second UE, the first SL-PRS within the first time slot. The apparatus receives, from the second UE, a second SL-PRS at a second time based on the first time slot and a response time associated with transmission of the second SL-PRS in response to the first SL-PRS. The apparatus measures a time difference between the transmission of the first SL-PRS and reception of the second SL-PRS to determine if a third SL-PRS is to be transmitted to the second UE.