UE Mobility Reception Timing for Active DL BWP Handover

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Solution Overview

Problem

In wireless communication systems, particularly 5G NR, handover failures occur due to UE switching to a default DL BWP during inactivity, leading to missed mobility information and increased latency, overhead, and power consumption, especially with frequent cell-level, TRP-level, and beam-level mobility.

Innovation Solution

Implementing a mobility reception timer and adjusting BWP inactivity timers to allow the UE to remain in an active DL BWP for additional time to monitor for mobility information, and providing UE assistance information (UAI) via valid uplink resources or multiplexing with node measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the UE switches to a default DL BWP during inactivity to save power, then power consumption is reduced, but mobility information is missed and handover failures occur

Engineering Contradiction:

Improvepower consumptionVSAvoidhandover reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The network configures the UE with a mobility reception timer before the BWP inactivity timer expires. This preliminary action ensures the UE remains in the active DL BWP long enough to receive mobility information (handover commands) from the network, preventing handover failures while still allowing power saving behavior after the mobility timer expires.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the UE's BWP state by introducing a mobility reception timer that overrides the default BWP switching behavior. The UE transitions from a static BWP switching pattern to a dynamic state where it remains in the active BWP during the mobility reception period, ensuring reliable reception of handover commands before returning to power-saving mode.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the UE remains in an active DL BWP to monitor for mobility information, then handover reliability is improved, but power consumption increases

Engineering Contradiction:

Improvehandover reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The network configures the mobility reception timer in advance, allowing the UE to know exactly when it needs to remain awake and monitor the active DL BWP for mobility information. This preliminary configuration prevents unnecessary extended monitoring, as the UE can switch to default BWP immediately after the mobility timer expires, minimizing power consumption while ensuring reliability during the critical reception window.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The mobility reception timer creates a defined periodic window during which the UE must remain in the active BWP to monitor for mobility information. After this periodic window closes, the UE returns to its power-saving BWP switching behavior, thus limiting power consumption to only the necessary duration for reliable handover reception.

Inventive Principle:

Principle #19Periodic action

3Use of energy by moving object

If the BWP inactivity timer expires quickly to enable fast power saving, then power consumption is reduced, but latency increases due to missed mobility information

Engineering Contradiction:

Improvepower consumptionVSAvoidhandover latency

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The network configures the mobility reception timer to extend beyond the BWP inactivity timer expiration point. This preliminary extension ensures that even when the BWP inactivity timer expires quickly for power saving, the UE has additional time configured to receive mobility information, thus preventing handover failures and reducing the effective latency without sacrificing power saving benefits.

Inventive Principle:

Principle #10Preliminary action

4Loss of time

If the network sends mobility information quickly to reduce latency, then handover speed is improved, but the UE may miss the information if it has switched to default BWP

Engineering Contradiction:

Improvehandover latencyVSAvoidmobility information reception

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The mobility reception timer dynamically adjusts the UE's BWP state to remain active during the critical period when mobility information is expected. This dynamic adjustment ensures the UE is in the correct state to receive quickly sent mobility information from the network, improving both reliability and effective handover speed without requiring the network to slow down its information transmission.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12477425B2Mobility enhancements and power saving for user equipment communication

Publication Date: 2025.11.18 QUALCOMM INC

AI summary

Apparatuses and methods for mobility enhancements and power saving considerations for UE are described. An apparatus is configured to operate on an active DL BWP in a source node, where the active DL BWP is not a default DL BWP associated with the UE, and start a BWP inactivity timer at the UE that triggers a BWP switch from an active DL BWP to the default DL BWP after the BWP inactivity timer expires at a first expiration time. The apparatus is also configured to report a measurement of at least one of the source node or a target node, and start a mobility reception timer based on a condition associated with at least one of the measurement of the source node being below a first signal quality threshold or the measurement of the target node being above a second signal quality threshold.