Carrier Phase Positioning with Multi-Frequency OFDM Signals
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Solution Overview
Problem
Carrier phase measurements in New Radio (NR) positioning face challenges such as integer ambiguity resolution and phase noise, which affect accuracy, and require additional methods like TDOA for calibration, limiting scalability and precision.
Innovation Solution
The use of multiple carrier OFDM signals for carrier phase measurements, allowing virtual frequency determination to resolve integer ambiguity and improve accuracy, with phase measurements taken in both frequency and time domains to mitigate multipath effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If carrier phase measurements are used for positioning, then positioning accuracy is improved, but integer ambiguity resolution becomes difficult
Solution Approach 1:
The patent transitions from single-frequency carrier phase measurements to multi-frequency OFDM carrier phase measurements. By measuring carrier phases across multiple frequencies (subcarriers), the system creates an additional dimensional space for resolving integer ambiguities. The multi-frequency measurements provide redundant information that enables the resolution of integer ambiguities through comparative analysis across different frequency dimensions, thereby maintaining high positioning accuracy while solving the ambiguity problem.
Solution Approach 2:
The patent changes the measurement parameters by utilizing multiple frequencies instead of a single carrier frequency. By varying the frequency parameter across multiple subcarriers in OFDM signals, the system obtains multiple carrier phase measurements with different wavelengths. This parameter variation enables the resolution of integer ambiguities through mathematical relationships between measurements at different frequencies, while preserving the high accuracy benefits of carrier phase positioning.
2Measurement precision
If TDOA method is used to resolve integer ambiguity, then positioning accuracy is improved, but scalability is limited
Solution Approach 1:
The patent enables the carrier phase measurement system to resolve its own integer ambiguities using intrinsic properties of multi-frequency OFDM signals, without requiring external TDOA positioning results or fixed known locations for calibration. The system uses the redundant information from multiple frequency measurements to self-determine integer ambiguities through mathematical relationships, making the system self-sufficient and scalable without dependency on additional calibration infrastructure.
Solution Approach 2:
The patent extracts and utilizes the redundant information contained in multi-frequency OFDM carrier phase measurements to resolve integer ambiguities. By separating and analyzing the phase measurements across different frequencies, the system isolates the integer ambiguity component and resolves it independently, eliminating the need for external TDOA methods or fixed calibration locations, thereby improving scalability.
3Measurement precision
If carrier phase measurements are performed frequently, then positioning accuracy is maintained, but new integer ambiguities are introduced
Solution Approach 1:
The patent performs preliminary action by establishing integer ambiguity resolution through multi-frequency measurements before conducting frequent carrier phase positioning measurements. By resolving integer ambiguities upfront using the redundant frequency information, the system creates a stable baseline that allows subsequent frequent measurements to maintain accuracy without introducing new ambiguities, as the integer components are already determined.
Solution Approach 2:
The patent implements feedback by using the consistent integer ambiguity solutions derived from multi-frequency measurements to validate and maintain positioning accuracy over time. The system continuously monitors carrier phase measurements across frequencies and uses the established integer ambiguity resolutions as feedback to detect and correct any drift or new ambiguities, enabling frequent measurements without losing accuracy or introducing errors.
Data Source
AI summary
A system and a method are provided in which a user equipment (UE) obtains a set of coefficients and a set of subcarriers from a location management function (LMF), and measures carrier phases on subcarriers, from the set of subcarriers, of a received reference signal transmitted with multi-carrier modulation. The UE determines a virtual carrier phase generated from the measured carrier phases and corresponding coefficients, from the set of coefficients. The UE reports the virtual carrier phase to the LMF.