UE Doppler Shift Delay Compensation for Non-Terrestrial Network Synchronization

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Solution Overview

Problem

Current methods for estimating signal propagation delay between non-terrestrial nodes and user equipment (UE) in wireless communications, especially in 5G New Radio systems, are inadequate, particularly when UE lacks GNSS capabilities or experiences GNSS outages, leading to degraded accuracy and system performance.

Innovation Solution

A method involving the UE estimating Doppler frequency shifts at different times to calculate signal propagation delay, which is then used to compensate for uplink transmissions, allowing for accurate timing adjustments without relying on GNSS, and transmitting parameters through uplink control information, Channel State Information reports, Medium Access Control Control Elements, and Physical Uplink Control Channels to a ground-based base station.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If GNSS-based location computation is used to determine propagation delay, then delay estimation accuracy is improved, but the system becomes inoperable when UE lacks GNSS capabilities or experiences GNSS outage

Engineering Contradiction:

Improvedelay estimation accuracyVSAvoidsystem operability without GNSS

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent transitions from GNSS-based location parameters to Doppler frequency shift parameters for delay estimation. By measuring Doppler shifts at different times and using the relationship between Doppler shift, velocity, and distance, the system calculates propagation delay without requiring GNSS location data, thus maintaining operability in non-GNSS environments while achieving acceptable delay estimation accuracy

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If cellular system is redesigned to accommodate unknown delay, then system flexibility is improved, but system performance degrades due to varying receive time

Engineering Contradiction:

Improvesystem flexibilityVSAvoidsystem performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the UE measures Doppler frequency shifts and reports them to the base station, which then uses this information to calculate and compensate for propagation delay. This closed-loop approach allows the system to adapt to varying delay conditions while maintaining reliable performance through continuous measurement and adjustment

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If Doppler frequency shift measurement is used to estimate propagation delay, then adaptability to non-GNSS environments is improved, but measurement complexity increases

Engineering Contradiction:

Improvenon-GNSS environment compatibilityVSAvoidDoppler frequency shift measurement complexity

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent leverages the UE's existing downlink signal reception and processing capabilities to perform Doppler frequency shift measurements. The UE already has the necessary hardware and software to receive and analyze downlink signals from NTN nodes, so it can self-service the delay estimation function using its existing resources without requiring additional specialized measurement equipment

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate estimation and compensation of signal propagation delay, ensuring proper timing and frequency synchronization even without GNSS, thereby enhancing system performance and reliability for UE communicating with non-terrestrial networks.

Implementation Method 1

estimating a first Doppler frequency shift in a downlink signal from the non-terrestrial network (NTN) node at a first time instance; estimating a second Doppler frequency shift in the downlink signal at a second time instance

Methodology Applied

Scientific EffectDoppler frequency shift: Doppler Effect

Data Source

PatentUS20240163815A1Reporting accuracy of timing and frequency synchronization associated with communications between a non-terrestrial node and a terrestrial node

Publication Date: 2024.05.16 SHARP KK

AI summary

A method for a user equipment (UE) communicating with a non-terrestrial network (NTN) node is provided. The method transmits one or more parameters to a ground-based base station (BS) communicatively coupled to the NTN node, the one or more parameters transmitted through at least one of uplink control information (UCI), a periodic Channel State Information (CSI) report with CSI information, a Medium Access Control (MAC) Control Element (CE), and a Physical Uplink Control Channel (PUCCH). The one or more parameters are transmitted to the ground-based BS for indicating accuracy of time and frequency synchronization associated with communication between the UE and the NTN node.