PRS Positioning in Unlicensed Bands via TRTD Segmentation
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Solution Overview
Problem
Current wireless communication systems face challenges in minimizing TRTD information and efficiently performing RTT positioning in unlicensed bands, particularly in V2X communication scenarios where precise timing differences are crucial for accurate positioning and communication reliability.
Innovation Solution
A method and apparatus for a user equipment (UE) in a wireless communication system that involves receiving positioning reference signal (PRS) configuration information, performing listen before talk (LBT) in the unlicensed band, transmitting a first PRS to an anchor node (AN), and receiving a second PRS, where the PRS configuration includes resource patterns and symbol numbers to acquire the Tx-Rx time difference (TRTD), represented as both coarse and fine TRTD information, to facilitate accurate RTT positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RTT positioning is performed in unlicensed bands using conventional methods, then positioning functionality is provided, but TRTD information size and measurement precision are insufficient for accurate positioning
Solution Approach 1:
The TRTD information is segmented into two distinct parts: coarse TRTD information (integer number of symbol periods) and fine TRTD information (fractional part within a symbol period). This segmentation allows each part to be optimized independently - the coarse part provides the basic timing framework while the fine part adds precision, thereby improving overall positioning accuracy without requiring excessively large information sizes
Solution Approach 2:
The patent introduces a new dimensional approach by measuring TRTD at two different granularity levels (symbol period level and fractional sample level). This dual-dimensional measurement strategy enables the system to capture both the overall timing relationship and the precise fractional offset, effectively increasing the information dimensionality and improving positioning precision
2Reliability
If PRS transmission is performed in unlicensed bands without LBT, then positioning reference signals can be transmitted, but communication reliability deteriorates due to channel conflicts
Solution Approach 1:
The patent implements LBT (Listen Before Talk) as a preliminary action before PRS transmission. The UE performs channel sensing and determines channel availability prior to transmitting positioning reference signals. This preliminary check prevents channel conflicts and collisions with other transmissions, ensuring reliable PRS reception while minimizing delays through efficient channel access
Solution Approach 2:
The UE autonomously performs LBT procedures and self-determines channel availability for PRS transmission without requiring network coordination. This self-service approach allows the UE to independently ensure reliable transmission conditions, reducing positioning time by avoiding scheduled coordination overhead while maintaining communication reliability
3Measurement precision
If detailed TRTD measurement is performed for high positioning accuracy, then positioning precision improves, but device complexity and processing requirements increase
Solution Approach 1:
The patent segments the TRTD measurement process into two distinct stages: coarse measurement (determining integer number of symbol periods) and fine measurement (determining fractional part within symbol period). This segmentation allows the system to first establish a rough timing estimate using simpler methods, then refine the measurement only where needed, reducing overall processing complexity while maintaining high precision
Solution Approach 2:
The patent applies partial action by measuring fine TRTD information only for the fractional component within each symbol period, rather than attempting to measure every aspect of the timing relationship at maximum precision. This partial measurement approach achieves sufficient positioning accuracy without the excessive processing requirements of complete high-precision timing analysis
Data Source
AI summary
An aspect of the present disclosure provides a method by a user device in a wireless communication system, the method comprising: receiving positioning reference signal (PRS) configuration information; performing listen-to-talk (LBT) for an unlicensed band; on the basis of the PRS configuration information, transmitting a first PRS to an anchor node (AN) on a channel in an idle state according to the LBT, among multiple channels included in the unlicensed band; and on the basis of the PRS configuration information, receiving a second PRS from the AN on the channel, wherein the first PRS is transmitted immediately after the LBT is performed.