PRS Sequence Duration Extension for NTN Positioning Ambiguity
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Solution Overview
Problem
Existing wireless communication systems, particularly in 5G New Radio (NR) networks, face challenges in accurately determining the time difference of arrival (OTDOA) of positioning reference signals (PRS) due to the short repetition period of PRS sequences, which can lead to ambiguity in propagation delays, especially in non-terrestrial networks (NTNs).
Innovation Solution
The proposed solution involves extending the repetition duration of PRS sequences to be greater than 10 milliseconds and at least twice the maximum differential delay, ensuring that the PRS sequences do not repeat within the possible propagation time between satellites and receivers. This is achieved by modifying the PRS sequence generator to include variables that adjust the sequence duration, such as the frame number or PRS burst index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the PRS sequence repetition period is kept short (10 ms or less), then the positioning measurement efficiency is improved, but the propagation delay ambiguity occurs in NTN scenarios
Solution Approach 1:
The patent applies dynamics by making the PRS sequence repetition period variable rather than fixed. The repetition period is dynamically adjusted based on the NTN scenario and maximum propagation delay requirements, allowing the system to adapt between short periods for terrestrial efficiency and extended periods for NTN accuracy.
Solution Approach 2:
The patent changes the temporal parameter of the PRS sequence repetition period from the conventional fixed 10 ms to an extended duration of at least twice the maximum differential delay. This parameter change eliminates propagation delay ambiguity in NTN while maintaining measurement efficiency through optimized sequence design.
2Measurement precision
If the PRS sequence repetition duration is extended to at least twice the maximum differential delay, then the OTDOA measurement accuracy is improved, but the signaling resource consumption increases
Solution Approach 1:
The patent segments the extended PRS sequence into multiple bursts transmitted over the extended repetition period. This segmentation allows the receiver to process and measure OTDOA across multiple bursts, improving measurement accuracy while distributing the signaling resource consumption over time rather than requiring a single large transmission.
Solution Approach 2:
The patent utilizes periodic transmission of PRS bursts within the extended repetition period. The periodic structure allows the receiver to accumulate measurements from multiple periods, improving OTDOA accuracy through averaging while managing signaling resource consumption through the regular, predictable transmission pattern.
Data Source
AI summary
Disclosed are techniques for positioning. A receiver measures a time of arrival (ToA) of a positioning reference signal (PRS) transmission of a first PRS sequence transmitted by a first transmitter, measures a ToA of a PRS transmission of a second PRS sequence transmitted by a second transmitter, and determines an observed time difference of arrival (OTDOA) as a difference between the ToA of the PRS transmission of the first PRS sequence and the ToA of the PRS transmission of the second PRS sequence, wherein the OTDOA is less than half a maximum differential delay expected between the PRS transmission of the first PRS sequence and the PRS transmission of the second PRS sequence, and wherein a repetition duration of the first PRS sequence and the second PRS sequence is greater than 10 milliseconds (ms) and at least twice the maximum differential delay.