Satellite Ephemeris Signaling for Predictive NTN Cell Coverage

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Solution Overview

Problem

In Non-Terrestrial Networks (NTN), UEs face challenges in determining cell coverage areas accurately and efficiently due to high path loss, interference, and variable propagation delays, which affect optimal cell selection and handover processes.

Innovation Solution

Providing UEs with cell coverage information associated with satellite ephemeris data, including area shape descriptions and time dependence, to enable accurate prediction of cell coverage areas within the validity time of ephemeris data, using principles such as independent and coexisting cell principles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If satellite ephemeris data is provided to UEs, then cell coverage prediction accuracy is improved, but signaling overhead and data transmission complexity increase

Engineering Contradiction:

Improvecell coverage prediction accuracyVSAvoidsignaling overhead

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The cell coverage information is segmented into multiple components including area shape descriptions (e.g., polygon vertices, ellipse parameters), time dependence indicators (validity time, update periodicity), and conditional coverage data. This segmentation allows efficient encoding and transmission of coverage predictions without overwhelming signaling overhead.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Cell coverage information is provided in advance through system information blocks and dedicated signaling before UEs need to perform cell selection or handover. This preliminary provision of coverage area, shape, and time validity data enables UEs to predict future coverage areas based on satellite ephemeris without requiring real-time measurements.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If cell coverage information is provided for multiple time instances, then mobility procedure optimization is improved, but information processing complexity increases

Engineering Contradiction:

Improvemobility procedure efficiencyVSAvoidinformation processing complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The cell coverage information includes dynamic elements such as time dependence indicators, validity periods, and update periodicity parameters. UEs can adapt their processing based on these dynamic characteristics, focusing computational resources on critical handover moments while using predictive models for routine cell selection, thereby managing complexity efficiently.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs parameter-based representations of cell coverage areas (e.g., polygon vertices, ellipse semi-axes, center coordinates) that can be efficiently updated over time. By changing only the relevant parameters rather than transmitting complete coverage maps, the system optimizes mobility procedures while controlling UE processing complexity through mathematical relationships.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If satellite beam width is increased to cover larger areas, then coverage area is improved, but intercell interference increases

Engineering Contradiction:

Improvecell coverage areaVSAvoidintercell interference

Core Design Contradiction:

Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent provides differentiated cell coverage information for different spatial locations and time instances. UEs receive precise coverage area descriptions that reflect local conditions, allowing them to accurately determine whether they are within a cell's coverage area. This local precision enables better cell selection decisions that avoid areas of high intercell interference while maintaining adequate coverage.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Cell coverage information acts as an intermediary between satellite beam characteristics and UE cell selection decisions. By providing processed coverage area, shape, and time validity data, the system mediates the relationship between wide satellite beams and individual UE decisions, enabling UEs to select appropriate cells based on predicted coverage without directly experiencing the full impact of beam width-related interference.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If ephemeris data validity time is extended, then data update frequency is reduced, but position prediction accuracy degrades

Engineering Contradiction:

Improvedata update efficiencyVSAvoidsatellite position prediction accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent provides cell coverage information with validity time that may extend beyond the strict ephemeris data validity period. By incorporating predictive models and uncertainty margins, the system provides partial coverage information that remains useful even after ephemeris data expires, reducing update frequency while maintaining adequate position prediction accuracy for cell selection purposes.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250350354A1Ephemeris data signaling with extensions indicating cell coverage

Publication Date: 2025.11.13 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method (1000) by a wireless device (110) is provided for determining cell coverage area provided by one or more satellites. The method includes receiving (1002) information at the wireless device. The wireless device uses (1004) the received information to obtain a location of the cell coverage area provided by the one or more satellites for a plurality of times.