Satellite Access Network Measurement Gap Scheduling
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Solution Overview
Problem
The significant Doppler shift in Non-Terrestrial Networks (NTN) and Satellite Access Networks (SAN) due to high-speed satellites complicates user equipment (UE) measurements, increasing hardware and software complexity and costs, as traditional terrestrial network assumptions do not apply.
Innovation Solution
Implementing time-division multiplexing (TDM) schemes that allow UE to perform measurements outside measurement gaps by applying scheduling restrictions, enabling data interruptions or adjustments in transmission/reception periods to manage Doppler shifts without requiring additional hardware or software resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional terrestrial network measurement methods are used in satellite networks, then the measurement process is simple, but the Doppler shift causes measurement errors and requires complex UE processing
Solution Approach 1:
The patent introduces measurement gap configurations as an intermediary mechanism that separates measurement activities from normal data transmission. The network configures specific time gaps during which UE can perform satellite/cell measurements without processing Doppler-shifted signals during active communication, thereby reducing processing complexity while maintaining measurement accuracy through proper timing alignment
2Measurement precision
If measurement gaps are configured for satellite measurements, then measurement accuracy is maintained, but data transmission is interrupted
Solution Approach 1:
The patent implements periodic measurement gap configurations where measurement activities are performed at regular, predetermined intervals rather than continuously. This periodic approach allows the system to maintain measurement accuracy by regularly sampling satellite/cell parameters while minimizing data transmission interruptions, as normal data flow can proceed during non-gap periods
Solution Approach 2:
The patent enables dynamic adjustment of measurement gap parameters including gap start positions, durations, and periodicities based on network conditions, satellite visibility, and traffic requirements. This dynamic configuration allows the system to adaptively balance measurement needs against data transmission efficiency, reducing interruptions when measurements are less critical while maintaining accuracy when satellite conditions change
3Measurement precision
If Doppler compensation is performed in UE, then measurement accuracy is improved, but hardware and software requirements increase
Solution Approach 1:
The patent uses measurement gap configurations as an intermediary that prevents the need for complex Doppler compensation in UE. By creating dedicated measurement periods with known timing relationships, the network provides reference signals that UE can measure without requiring sophisticated Doppler estimation and compensation algorithms, thereby maintaining frequency measurement accuracy while reducing UE complexity
Solution Approach 2:
The patent replaces the mechanical/algorithmic approach of Doppler compensation in UE with a network-controlled timing approach. Instead of requiring UE to actively compensate for Doppler effects through complex signal processing, the system uses pre-configured measurement gaps with synchronized reference signals, substituting sophisticated UE-side signal processing with simpler timing-based measurement procedures
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 efficient satellite/cell measurements in NTN/SAN without increasing UE burdens, supporting multiple cell/satellite connectivity and mobility performance while balancing data reception and design costs.
Implementation Method 1
One of the challenges in NGSO communications is that the Doppler shift is huge since the NGSO satellites move at a high speed. The Doppler shift of a LEO-600 km network can be up to 24 parts per million (ppm). For example, in the 2 gigahertz (GHz) carrier, the maximum Doppler shift of a LEO satellite can be up to +/â48 kilohertz (kHz).
Data Source
AI summary
Various solutions for satellite access network (SAN) or non-terrestrial network (NTN) measurement and data scheduling with respect to user equipment and network apparatus in mobile communications are described. An apparatus may determine whether to perform a measurement outside a measurement gap for a neighboring cell. The apparatus may apply a scheduling restriction within a time period in an event that the measurement is determined. The apparatus may transmit uplink symbols or receiving downlink symbols outside the time period with the scheduling restriction.