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LTE ANR-Related Neighbor Measurement Flow Call Flow

call-flow LTE | ANR | Optimization | Measurements

LTE ANR-related neighbor measurement flow is the optimization-facing measurement path used to discover or validate neighbor relations through UE-side reporting.

This page focuses on neighbor discovery and optimization use rather than direct handover execution.

Introduction

The eNB configures measurement behavior that exposes neighbor-cell observations, the UE reports the result, and the network uses that information for ANR-related optimization and neighbor validation.

Use this page when the trace is about neighbor discovery, missing neighbors, or optimization behavior instead of a single mobility action.

What Is ANR-Related Neighbor Measurement Flow in Simple Terms?

What starts the procedure: The network needs UE-side measurement help to discover or validate neighbor relations.
What the UE and network want to achieve: Collect neighbor observations that can improve ANR and later mobility behavior.
What success looks like: The UE reports the relevant neighbor context and the network can use it for ANR analysis.
What failure means: The expected neighbor is never reported, is reported incorrectly, or cannot be turned into useful ANR context.

Why this procedure matters

This page is useful when the real issue is missing or bad neighbor context behind later handover behavior.

Quick Fact Sheet

Procedure name	LTE ANR-Related Neighbor Measurement Flow
Domain	Optimization and neighbor discovery
Main trigger	The network needs UE-side neighbor visibility
Start state	UE is connected with relevant measurement behavior active
End state	Neighbor observation is available for ANR use
Main nodes	UE, eNB
Main protocols	RRC
Main success outcome	Useful neighbor observation becomes available
Main failure outcome	Missing or misleading neighbor context
Most important messages	Measurement Control, Measurement Report
Main specs	TS 36.331 plus implementation-specific ANR handling

LTE ANR-Related Neighbor Measurement Flow — Click the diagram to open the full-size in a new tab.

Preconditions

The UE is already in connected LTE service.
Neighbor discovery or validation is relevant to the current optimization scenario.
Measurement configuration exposes the needed neighbor scope.

Nodes and Interfaces

Nodes involved

Node	Role in this procedure
UE	Applies measurement rules, performs the configured observations, and sends the relevant result back to the network.
eNB	Configures measurement behavior, interprets results, and uses them for mobility, optimization, or analytics decisions.

Interfaces used

Interface	Path	Role
LTE Uu	UE <-> eNB	Carries measurement configuration, reporting, and any later control action based on the result.

End-to-End Call Flow

UE                    eNB
|<--neighbor measurement config--|
|--neighbor observation report-->|
|   ANR / optimization use       |

Major Phases

Phase	What happens
1. Neighbor-oriented setup	The eNB configures the measurement scope needed for neighbor discovery or validation.
2. Neighbor observation	The UE measures the relevant neighbor cells.
3. Reporting	The UE returns the neighbor observation result.
4. ANR use	The network uses the result for neighbor relation analysis or optimization.

Step-by-Step Breakdown

Step 1: Configure neighbor-oriented measurement

Sender -> receiver: eNB -> UE

Message(s): Measurement Control

Purpose: Enable the measurement scope needed for ANR-related analysis.

State or context change: The UE begins monitoring the neighbor context relevant to the scenario.

Note: This is an optimization-facing use of measurement configuration.

Step 2: Observe the neighbor context

Sender -> receiver: UE

Message(s): Neighbor measurement activity

Purpose: Collect the neighbor-cell observations that ANR logic needs.

State or context change: The UE has the neighbor information required for reporting.

Note: The goal here is visibility into neighbor relations rather than a single immediate handover.

Step 3: Return the observation

Sender -> receiver: UE -> eNB

Message(s): Measurement Report

Purpose: Return the neighbor observation to the eNB.

State or context change: The network now has UE-side evidence about the neighbor relation.

Note: This is the key measurement output for ANR-related analysis.

Step 4: Use the result for ANR

Sender -> receiver: Network

Message(s): ANR or optimization handling

Purpose: Use the reported neighbor information in relation management or analysis.

State or context change: The observation becomes part of the optimization workflow.

Note: The later optimization action is implementation-specific.

Important Messages

Message	Protocol	Direction	Purpose in this procedure	What to inspect briefly
Measurement Report	RRC	UE -> eNB	Returns the neighbor-cell observation that ANR can use.	Check the reported neighbor identity and whether it matches the missing or suspect relation.
Measurement Control	RRC	eNB -> UE	Defines the neighbor-oriented observation scope.	Check whether the suspected neighbor was actually included in the active measurement scope.

Important Parameters to Inspect

Parameter	What it is	Where it appears	Why it matters	Common issues
Neighbor identity	The cell or relation being observed.	Measurement Report	Shows which neighbor the UE actually saw.	The wrong neighbor is assumed from the report.
Measurement scope	The configured neighbor layer or cell set.	Measurement Control	Explains whether the missing neighbor was even eligible to be observed.	The suspected neighbor was never part of the scope.
Report timing	When the UE returned the neighbor result.	Trace timing	Useful for deciding whether the neighbor was stably visible.	A short-lived observation is treated as a stable ANR candidate.
Layer or frequency context	The LTE layer on which the neighbor was seen.	Measurement Report	Important for neighbor planning and later mobility use.	The relation is interpreted without the right layer context.
Optimization outcome	The ANR-facing result of the report.	Follow-up analysis	Shows whether the report was actually useful to the network.	The report exists but no later ANR interpretation follows.

Successful Completion

Success means the UE reports useful neighbor context that can be used for ANR-related analysis or relation validation.

Common Failures and Troubleshooting

Symptom	Likely cause	Where to inspect	Relevant message(s)	Relevant interface(s)	Likely next step
Missing neighbor never appears in reports	The neighbor is not measurable in the configured scope or is not actually visible to the UE.	Measurement Control and later reports.	Measurement Report	LTE Uu	Check whether the missing neighbor was included in the configured observation scope.

What to Check in Logs and Traces

Check whether the missing neighbor was configured to be observable.
Read the reported neighbor identity directly from the report instead of inferring it later.
Correlate the report timing with the optimization scenario being investigated.

Related sub-procedures

Related message reference pages

Related troubleshooting pages

Notes

ANR-related neighbor measurement is optimization-facing. The value of the procedure is in understanding neighbor visibility before later mobility behavior is judged.

FAQ

What is LTE ANR-Related Neighbor Measurement Flow?

It is the LTE measurement path used to discover or validate neighbor relations through UE-side observations.