Satellite Signal Propagation Delay Compensation in NTN
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Solution Overview
Problem
In Non-Terrestrial Network (NTN) scenarios, the propagation delay of satellite signals varies due to satellite movement, causing measurement signal timing to drift, which can result in terminals missing neighboring satellite cell SSBs for Radio Resource Management (RRM) measurements, affecting handover performance.
Innovation Solution
The system compensates for satellite signal propagation delay variation by transmitting ephemeris data and cell measurement window specifications to terminals, allowing them to adjust their measurement windows to align with changing signal arrival times, ensuring that measurement signals from neighboring cells are received within the defined windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurement windows are used for neighboring cell measurements, then terminals can perform RRM measurements, but propagation delay variation causes measurement signals to arrive outside the measurement windows
Solution Approach 1:
The patent applies dynamics by making the measurement window timing adaptive rather than fixed. The network configures measurement windows based on satellite ephemeris data, allowing the measurement window positions and durations to dynamically adjust according to the varying propagation delays caused by satellite movement. This ensures measurement signals arrive within the configured windows despite changing delay conditions.
Solution Approach 2:
The patent applies preliminary action by having the network proactively configure measurement windows before measurements are performed. Using satellite ephemeris data, the network predicts propagation delay variations and pre-configures appropriate measurement window parameters, enabling terminals to reliably capture measurement signals without requiring real-time delay compensation during the measurement process.
2Ease of operation
If fixed measurement window timing is used, then terminal operation is simplified, but satellite movement causes timing drift and measurement failure
Solution Approach 1:
The patent applies parameter changes by modifying measurement window parameters (timing, duration, periodicity) based on satellite propagation delay characteristics. Instead of using fixed timing, the network configures variable parameters that adapt to the changing delay conditions, maintaining measurement reliability while keeping terminal operations straightforward through network-provided configuration.
3Reliability
If measurement windows are extended to accommodate delay variation, then measurement signal reception is improved, but time resources are consumed
Solution Approach 1:
The patent applies local quality by configuring different measurement window parameters for different cells or signal conditions. Instead of uniformly extending all measurement windows, the network tailors window duration and timing to the specific propagation delay characteristics of each satellite cell, ensuring adequate reception reliability while minimizing unnecessary time resource consumption.
Data Source
AI summary
Satellite signal propagation delay variation can be compensated by transmitting ephemeris data of a satellite and cell measurement window specifications to a terminal, receiving an indication from the terminal that a cell measurement signal will arrive at the terminal outside of a time frame defined by the cell measurement window specifications, modifying the cell measurement window specifications based on a difference in propagation delay between a serving cell, which defines the cell measurement window specifications, and a neighboring cell, which transmits the cell measurement signal, so that the cell measurement signal will arrive at the terminal within the time frame defined by the cell measurement window specifications, the satellite providing communication with the terminal for at least one of the serving cell and the neighboring cell, and transmitting modified cell measurement window specifications to the terminal.