Pre-configured Measurement Gap (Pre-MG)

Key Terminology

Term	Definition
Pre-MG	Pre-configured Measurement Gap - pattern configured but conditionally active
preConfigInd	RRC indicator marking a measurement gap as pre-configured
preConfGapStatus	RRC indication for network-controlled activation/deactivation
per-UE Pre-MG	Single measurement gap across all serving cells
per-FR Pre-MG	One or two gaps configured per Frequency Range (FR1/FR2)

UE Capability Requirements

Capability IE	Mechanism
preconfiguredUE-AutonomousMeasGap	UE autonomously controls activation/deactivation
preconfiguredNWControlledMeasGap	Network controls via RRC signaling

Precedence

When UE supports both mechanisms, network-controlled takes precedence if preConfGapStatus is provided for all DL BWPs.

Requirements Apply When

UE indicates support of autonomous and/or NW-controlled Pre-MG
Network pre-configures single per-UE MG or one/two per-FR MGs
Gap pattern is one of #0 - #25 (Table 9.1.2-1)
UE is in NR SA with single carrier or NR CA

Supported Gap Patterns

All patterns #0 to #25 defined in Table 9.1.2-1 can be configured as Pre-MG.

Reference

Pattern applicability defined in Table 9.1.2-3

Status Logic

Activation Mechanisms

Autonomous (UE-Controlled)

Mechanism 1

Activated

At least one configured measurement requires gaps

Network-Controlled

Mechanism 2

Measurements WITHOUT Gaps

•SSB-based intra-frequency measurements (if Clause 9.2.1 conditions met)
•SSB-based inter-frequency measurements (if Clause 9.3.1 conditions met)
•CSI-RS-based intra-frequency measurements

Measurements REQUIRING Gaps

•SSB-based intra-frequency (if Clause 9.2.1 conditions NOT met)
•SSB-based inter-frequency (if Clause 9.3.1 conditions NOT met)
•CSI-RS-based inter-frequency measurements
•E-UTRA Inter-RAT measurements
•UTRA Inter-RAT measurements

Behavior and Special Cases

Reception/Transmission Behavior

Pre-MG Status	UE Behavior During Gap Occasion
per-UE ACTIVATED	UE not required to conduct Rx/Tx on corresponding serving cells (same as per-UE MG in 9.1.2)
per-UE DEACTIVATED	UE can be scheduled for Rx/Tx on all serving cells
per-FR ACTIVATED	UE not required to conduct Rx/Tx on serving cells in that FR (same as per-FR MG in 9.1.2)
per-FR DEACTIVATED	UE can be scheduled for Rx/Tx on all serving cells in that FR

PRS Measurements

When Pre-MG is used for PRS measurements, UE informs network of start/stop via LocationMeasurementIndication procedure.

Measurement Period Considerations

Scenario: Activated to Deactivated (Measurement REQUIRES gaps)

Measurement requirements do not apply

Critical Notes & Pitfalls

Precedence Rule

When UE supports both autonomous and network-controlled mechanisms, autonomous rules are overridden if network provides preConfGapStatus for all configured CCs.

1Immediate Status: UE determines Pre-MG status immediately after configuration or upon triggering condition.
2Joint Evaluation: UE must evaluate all concurrent triggering conditions jointly.
3Inter-RAT Always Needs Gaps: E-UTRA and UTRA inter-RAT measurements always require gaps.

Reference

Quick Reference: Decision Flow

Pre-MG Configured?
    |
    +--> Network provides preConfGapStatus for all BWPs/CCs?
    |       |
    |       +--> YES --> Use Network-Controlled mechanism
    |       |           +--> Check preConfGapStatus = '1' for activation
    |       |
    |       +--> NO  --> Use Autonomous mechanism
    |                   +--> Evaluate if all measurements can be done without gaps
    |                           |
    |                           +--> YES --> DEACTIVATED
    |                           +--> NO  --> ACTIVATED

Related Clauses

Clause	Content
9.1.2	MG interruption requirements
9.2.1	SSB intra-freq without gaps
9.3.1	SSB inter-freq without gaps
Table 9.1.2-1	Gap pattern definitions
Table 9.1.2-3	Pattern applicability