Assisted Beam Tracking for NTN User Equipment

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Solution Overview

Problem

In non-terrestrial network (NTN) communication systems, User Equipment (UE) faces challenges in tracking beams generated by mobile non-terrestrial base stations, leading to frequent beam failures due to the dynamic change in beam coverage areas and the rapid movement of base stations.

Innovation Solution

The NTN determines candidate beams for UE reselection based on the geographical location of the UE and the non-terrestrial locations of base stations, and transmits an indication of these candidate beams to the UE, allowing the UE to reselect a subsequent beam autonomously or with assistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE autonomously tracks beams without NTN assistance, then the UE can maintain independence and reduce network overhead, but beam failure occurs frequently due to rapid satellite movement and dynamic beam coverage changes

Engineering Contradiction:

Improvebeam tracking reliabilityVSAvoidbeam reselection complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The NTN base station acts as an intermediary that provides candidate beam information to the UE. The network determines and transmits indications of candidate beams that the UE should consider for reselection, mediating between the complex beam management requirements and the UE's tracking capabilities. This resolves the contradiction by having the network handle the complex determination of suitable beams while the UE simply follows the guidance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The NTN base station performs preliminary determination of candidate beams before the UE needs to reselect. The network proactively identifies and communicates candidate beam information to the UE in advance, allowing the UE to prepare for beam reselection without having to perform complex real-time analysis during beam failures.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the UE performs frequent beam measurements and reselection, then the UE can track moving beams more accurately, but system and UE resource consumption increases

Engineering Contradiction:

Improvebeam tracking accuracyVSAvoidUE energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The NTN base station performs the energy-intensive task of determining candidate beams using its own resources and capabilities. Instead of requiring the UE to continuously measure and evaluate multiple beams, the network self-services by calculating and providing candidate beam indications, significantly reducing UE energy consumption while maintaining tracking accuracy.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The UE performs only partial beam tracking operations by following network-provided candidate beam indications rather than performing exhaustive beam measurements. The network performs the excessive or complete analysis of beam suitability, and the UE executes only the necessary reselection actions based on network guidance.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If the NTN provides detailed candidate beam information to the UE, then the UE can make more informed reselection decisions, but the downlink signaling overhead increases

Engineering Contradiction:

Improvebeam reselection accuracyVSAvoiddownlink signaling data

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential candidate beam information needed for UE reselection decisions, rather than transmitting complete beam parameter sets. The network determines comprehensive beam suitability but communicates only the critical indications (such as candidate beam identifiers or simplified parameters) that the UE needs to perform reselection, reducing downlink signaling overhead while maintaining reselection accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If the UE remains in connected state to maintain beam tracking, then beam tracking can be more accurate, but system resources are consumed continuously

Engineering Contradiction:

Improvebeam tracking fidelityVSAvoidsystem resource consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The NTN base station provides candidate beam information to the UE in advance, even when the UE is in inactive or idle states. This preliminary provision of tracking information allows the UE to maintain beam tracking capability without remaining in a connected state, enabling accurate beam reselection when the UE transitions back to connected state while conserving system resources during idle periods.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250047372A1Assisted beam tracking for user equipment

Publication Date: 2025.02.06 GOOGLE LLC

AI summary

A non-terrestrial, wireless communications network (NTN) can assist User Equipments (UEs) in tracking beams generated by NTN base stations for reselection purposes. The NTN determines one or more candidate beams to which the UE can reselect (e.g., while the UE is in an inactive or idle state with respect to controlling radio resources) based on a geographical location of the UE and respective existing and/or predicted non-terrestrial locations of one or more non-terrestrial base stations of the NTN. The NTN transmits an indication of the one or more candidate beams to the UE (and optionally other beam-related information, such as radio access resources and relative priorities), and the UE can reselect a subsequent beam based on the indication received from the NTN. The UE can locally store a mapping of candidate reselection beams to geographical locations for ease and efficiency of future reselections.