NTN Uplink Repetition Timing Compensation for Moving Satellites
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Solution Overview
Problem
Non-terrestrial networks face challenges in handling repetitive uplink transmissions due to rapid changes in timing advance caused by the movement of satellites or airborne vehicles, leading to transmission failures and decoding issues, particularly for IoT devices with limited power and battery life.
Innovation Solution
The solution involves dynamically adjusting the timing advance configuration for repetitive uplink transmissions by applying a compensation factor to the timing advance parameter during the transmission process, combined with partial cancellation of repetitions, to maintain synchronization with the satellite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If repetitive uplink transmissions are used to ensure reliable data delivery in NTN, then transmission reliability is improved, but timing synchronization deteriorates due to rapid changes in timing advance caused by satellite movement
Solution Approach 1:
The system pre-calculates and applies timing advance compensation values before transmissions occur. The base station determines compensation values based on predicted satellite position changes and applies them proactively to upcoming repetitive transmissions, preventing timing drift before it degrades synchronization accuracy.
Solution Approach 2:
The timing advance configuration is made dynamic rather than static. The system continuously updates timing advance compensation values based on real-time satellite movement patterns, ensuring that each repetitive transmission is adjusted to current orbital conditions rather than using a fixed timing value throughout the repetition series.
2Measurement precision
If timing advance compensation is applied to maintain synchronization, then timing accuracy is improved, but system complexity increases due to dynamic adjustment mechanisms
Solution Approach 1:
The base station acts as an intermediary that centralizes the complex timing compensation calculations. Rather than requiring individual user equipment to perform complex orbital mechanics calculations, the base station receives satellite ephemeris data, computes timing advance compensation values, and distributes them to user equipment, simplifying the implementation at the terminal side.
Solution Approach 2:
The system changes the timing advance parameter dynamically based on satellite orbital parameters. By linking timing advance adjustments to measurable orbital elements (such as satellite position, velocity, and acceleration), the system maintains timing accuracy through parameter adaptation rather than through complex control algorithms.
3Measurement precision
If timing advance updates are performed frequently to track satellite movement, then synchronization is improved, but power consumption increases for battery-powered IoT devices
Solution Approach 1:
The system implements periodic timing advance updates rather than continuous adjustments. Timing advance compensation values are updated at specific intervals corresponding to satellite orbital periods or significant position changes, allowing IoT devices to enter low-power states between updates while maintaining adequate synchronization accuracy.
Solution Approach 2:
The system applies partial timing advance compensation by updating values only when satellite movement exceeds a threshold or at predetermined intervals rather than continuously. This partial action approach maintains sufficient synchronization for reliable communication while significantly reducing the processing and power consumption requirements compared to continuous tracking.
Data Source
AI summary
A method of operating a terminal in a non-terrestrial network “NTN” in a telecommunication system comprising the terminal configured to communicate with a base station via the NTN node. The method comprises identifying an uplink transmission to be transmitted as an uplink repetition series comprising a plurality of repetitions; identifying a first timing advance value for use as a current timing advance value for transmitting the uplink repetition series; identifying a first number N1 of repetitions; transmitting, based on the first number N1, a first set of repetitions of the uplink repetition series, using the first timing advance value; determining a second timing advance value; modifying a transmission timing of the uplink repetition series, wherein modifying the transmission timing comprises updating the current timing advance value to the second timing advance value; and transmitting a second set of repetitions of the uplink repetition series using the current timing advance value.