NTN Timing Advance Updates Using Doppler Frequency Compensation
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Solution Overview
Problem
Non-terrestrial networks face challenges in signal timing and frequency adjustments due to long propagation delays and moving cells, particularly in systems with airborne or spaceborne communication entities, requiring enhanced timing adjustments to optimize communication efficiency.
Innovation Solution
A unified framework for timing advance adjustments in non-terrestrial networks (NTNs) is proposed, incorporating methods for adjusting and updating timing advance based on Doppler measurements and considering different scenarios with regenerative and transparent payloads, including systems with or without equipment and signaling of location and velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If timing advance adjustments are made in non-terrestrial networks, then communication efficiency is improved, but signal timing and frequency adjustments become more complex due to long propagation delays and moving cells
Solution Approach 1:
The system performs preliminary timing advance adjustments based on predicted satellite positions and Doppler measurements before actual communication occurs. The network side calculates expected timing offsets using orbital parameters and applies pre-compensation to counteract known propagation delays and frequency shifts, reducing the complexity of real-time adjustments.
Solution Approach 2:
The patent implements feedback mechanisms where the network side continuously monitors uplink signal timing and frequency offsets, compares them against predicted values based on satellite ephemeris, and dynamically adjusts timing advance commands. This closed-loop feedback system optimizes timing synchronization while adapting to actual channel conditions, resolving the contradiction between efficiency and complexity.
2Measurement precision
If Doppler measurements and timing advance updates are continuously performed, then synchronization accuracy is improved, but processing overhead and computational requirements increase
Solution Approach 1:
The system performs Doppler measurements and timing advance updates periodically rather than continuously. Timing advance commands are updated at specific intervals based on satellite orbital characteristics and channel conditions, maintaining synchronization accuracy while reducing processing overhead. The periodic updates are scheduled according to predicted timing drift rates.
Solution Approach 2:
The patent applies partial updates by only adjusting timing advance parameters when deviations exceed predefined thresholds, rather than continuously updating all parameters. This selective update approach maintains synchronization accuracy for critical parameters while minimizing unnecessary processing overhead for stable connections.
3Reliability
If timing advance values are adjusted frequently to compensate for moving cells, then communication reliability is improved, but uplink timing alignment becomes more difficult to maintain
Solution Approach 1:
The network side acts as an intermediary that centralizes timing advance calculations and management. Rather than requiring UE devices to autonomously track and adjust timing for moving satellites, the network side computes timing advance commands based on satellite ephemeris and channel measurements, then delivers these commands to UEs. This intermediary approach simplifies UE operation while maintaining reliable timing alignment through centralized control.
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
The framework enhances communication efficiency by optimizing timing adjustments in non-terrestrial networks, addressing long propagation delays and moving cells, ensuring robust synchronization and frequency compensation, and enabling seamless communication links.
Implementation Method 1
computes a second timing advance value based on a first timing advance value, a first determined frequency, and a second determined frequency
Data Source
AI summary
Apparatuses, methods, and systems are disclosed for timing and frequency adjustments in non-terrestrial networks. One apparatus includes a processor that determines a first frequency from one of a first reference signal received from a mobile wireless communication network and a configuration message received from the mobile wireless communication network. The processor determines a second frequency from a second reference signal received from the mobile wireless communication network. The processor computes a second timing advance value based on a first timing advance value, the first determined frequency, and the second determined frequency, the first timing advance value received as part of a control message. The apparatus includes a transceiver that transmits, to the mobile wireless communication network, an uplink signal using the second timing advance value.