NTN Reconnection Control During Out-of-Coverage Periods

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Solution Overview

Problem

In non-terrestrial networks (NTNs), user equipment (UE) experiences significant battery power wastage due to continuous cell searching and timer expiration during discontinuous coverage, leading to prolonged delays in data transmission and radio link failures.

Innovation Solution

The UE refrains from seeking reconnection during out-of-coverage periods and transitions to an idle state until it reenters coverage, while the RAN node releases reserved communication resources with a timer-based RRC release message to manage resource usage efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE continuously performs cell searching and connection attempts during out-of-coverage periods, then the UE can quickly reestablish connection when coverage is restored, but the UE battery power is significantly wasted and unnecessary delays occur

Engineering Contradiction:

Improveconnection reestablishment reliabilityVSAvoidUE battery power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The network performs preliminary actions by determining predicted coverage areas and proactively releasing resources before the UE actually goes out of coverage. The RAN node uses satellite orbital information to predict when the UE will be out of coverage and releases resources in advance, preventing the UE from wasting battery power on futile connection attempts while ensuring quick reconnection when coverage returns.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where the RAN node receives satellite ephemeris information and orbital data, processes this information to determine predicted coverage areas, and uses this feedback to make intelligent resource management decisions. The feedback loop allows the network to adapt resource allocation based on real-time satellite positions and predicted coverage changes.

Inventive Principle:

Principle #23Feedback

2Productivity

If the RAN node maintains reserved communication resources for the UE during out-of-coverage periods, then the UE can quickly resume communication when coverage is restored, but unnecessary resource consumption occurs

Engineering Contradiction:

Improvecommunication resumption speedVSAvoidnetwork resource consumption

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The RAN node takes preliminary action by proactively releasing reserved communication resources before the UE actually loses coverage. By using satellite orbital information to predict out-of-coverage periods, the network releases resources in advance, eliminating wasteful resource consumption while maintaining the ability to quickly allocate resources when the UE returns to coverage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the state of communication resources dynamically based on predicted coverage conditions. Resources are released from a reserved state to an available state based on timing information and satellite position parameters, allowing the network to optimize resource utilization by adapting resource allocation to actual coverage conditions rather than maintaining static reservations.

Inventive Principle:

Principle #35Parameter changes

3Loss of time

If the UE attempts RRC connection resume procedure during out-of-coverage periods, then the UE can quickly reconnect when coverage is restored, but timer expiration occurs and radio link failures are triggered

Engineering Contradiction:

Improveconnection restoration timeVSAvoidconnection establishment reliability

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The network applies preliminary anti-action by preemptively releasing resources and notifying the UE of predicted out-of-coverage periods. This prevents the UE from initiating futile RRC connection resume procedures that would lead to timer expiration and radio link failures. The UE uses the predicted coverage information to suppress connection attempts during out-of-coverage periods, avoiding the harmful effects of repeated failures.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS20260067190A1Managing communications and out-of-coverage scenarios in a non-terrestrial network

Publication Date: 2026.03.05 GOOGLE LLC

AI summary

A UE and a RAN node that communicate via an NTN operate to avoid wasting radio communication resources and UE's battery power during an out of NTN coverage. Upon determining that the UE is out of NTN coverage, the UE refrains from seeking to reconnect until determining the UE is in the NTN coverage. Upon detecting an upcoming out of coverage period, the RAN node sends an RRC release message to the UE. The RRC release message may include a timer value exceeding an estimated duration of the upcoming out of coverage, the UE waiting a time interval corresponding to the timer value before attempting to reconnect.