Complementary Timing Information for PRS in Non-Terrestrial Networks
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Solution Overview
Problem
In 5G wireless communication systems, non-terrestrial vehicles (NTVs) face challenges in accurately determining the time difference of arrival (OTDOA) of positioning reference signals (PRS) due to the ambiguity caused by PRS sequence repetition, which exceeds propagation delays, leading to incorrect timing measurements.
Innovation Solution
NTVs transmit complementary timing information alongside PRS sequences to distinguish between repetitions, allowing receivers to accurately determine the OTDOA by clarifying the radio frame and sequence index, thus resolving the ambiguity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If PRS sequences are transmitted with long periodicity to cover large propagation delays in NTN, then coverage area is improved, but timing measurement accuracy deteriorates due to sequence repetition ambiguity
Solution Approach 1:
The PRS transmission is segmented into multiple radio frames, with each frame containing a PRS sequence repetition. Complementary timing information is added to each segment to identify its position within the overall transmission structure, allowing the receiver to distinguish between different segments and resolve timing ambiguity while maintaining long periodicity for wide coverage
Solution Approach 2:
Complementary timing information acts as an intermediary element that bridges the gap between long-periodicity PRS transmissions and accurate timing measurements. This additional information layer provides the receiver with the necessary context to correctly interpret the timing of each PRS repetition without requiring shorter transmission periodicity
2Measurement precision
If complementary timing information is added to distinguish PRS repetitions, then timing measurement accuracy is improved, but signaling overhead increases
Solution Approach 1:
Complementary timing information is transmitted locally with each PRS repetition or radio frame, providing just enough timing context at the appropriate granularity level. This localized approach ensures accurate timing measurement without requiring excessive global signaling, as each local segment carries only the specific timing information needed for that segment
3Area of stationary object
If PRS sequence repetition is used to extend coverage in NTN, then coverage area is improved, but reliability of positioning deteriorates due to timing ambiguity
Solution Approach 1:
Complementary timing information is prepared and transmitted in advance with each PRS repetition, providing the receiver with predetermined timing context before the actual timing measurement is performed. This preliminary provision of timing information eliminates ambiguity and ensures reliable positioning measurements across the extended NTN coverage area
Data Source
AI summary
Disclosed are techniques for positioning. A receiver receives complementary timing information associated with the positioning reference signals (PRS) of a repetition of a PRS sequence. The complementary timing information distinguishes a repetition of a PRS sequence from remaining repetitions of the PRS sequence. Based on the complementary timing information associated with different PRS from different non-terrestrial vehicles indicating that the PRS were transmitted during the same radio frame, the receiver can determine an observed time difference of arrival (OTDOA) between the PRS received from the respective non-terrestrial vehicles.