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LTE Measurement Reporting Procedure Call Flow

call-flow LTE | Measurements | RRC

LTE measurement reporting is the general procedure that returns connected-mode radio results from the UE to the eNB after the configured trigger becomes true.

This page is the umbrella view of Measurement Report before you move into one specific event such as A3 or B1/B2.

Introduction

The eNB first configures measurement behavior, the UE monitors the configured cells or systems, and then the UE sends Measurement Report once the reporting rule is satisfied.

Use this page when the main question is how the generic reporting path works rather than what one exact event means.

What Is Measurement Reporting Procedure in Simple Terms?

What starts the procedure: A valid measurement configuration is already active in connected mode.
What the UE and network want to achieve: Return a radio result that the eNB can use for mobility, optimization, or analytics.
What success looks like: Measurement Report appears with the expected identity, target, and timing.
What failure means: The report never appears, appears with the wrong target, or appears at the wrong time.

Why this procedure matters

This is the general measurement result path behind many LTE handovers and optimization actions. It is often the fastest place to confirm whether the UE really reported what the network needed.

Quick Fact Sheet

Procedure name	LTE Measurement Reporting Procedure
Domain	Connected-mode measurement result delivery
Main trigger	Configured report condition becomes true
Start state	UE is in connected mode with active measurement setup
End state	Measurement result is delivered to the eNB
Main nodes	UE, eNB
Main protocols	RRC
Main success outcome	Expected Measurement Report is delivered correctly
Main failure outcome	Missing or misleading report
Most important messages	Measurement Report
Main specs	TS 36.331

LTE Measurement Reporting Procedure — Click the diagram to open the full-size in a new tab.

Preconditions

A valid measurement configuration is already active.
The UE is still in connected LTE service.
The relevant radio condition can be observed in the live scenario.

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
|   monitor condition     |
|--Measurement Report---->|
|   later control use     |

Major Phases

Phase	What happens
1. Active monitoring	The UE follows the previously configured measurement rules.
2. Trigger satisfaction	The report condition becomes true.
3. Report delivery	The UE sends Measurement Report to the eNB.
4. Result use	The eNB uses the result for later control logic.

Step-by-Step Breakdown

Step 1: Monitor the configured scope

Sender -> receiver: UE

Message(s): Measurement monitoring

Purpose: Watch the serving cell, neighbors, frequency layers, or RATs included in the active configuration.

State or context change: The UE is evaluating whether the report trigger becomes true.

Note: This is still configuration-driven behavior rather than a standalone message exchange.

Step 2: Detect a valid trigger

Sender -> receiver: UE

Message(s): Event or threshold satisfaction

Purpose: Reach the reporting condition defined by the active measurement rule.

State or context change: The UE is now eligible to send the report.

Note: Trigger timing must still satisfy the configured stability controls.

Step 3: Send Measurement Report

Sender -> receiver: UE -> eNB

Message(s): Measurement Report

Purpose: Return the measurement result to the eNB.

State or context change: The eNB now has a usable radio observation for later decisions.

Note: This is the main message to correlate with later mobility behavior.

Step 4: Use the report

Sender -> receiver: eNB

Message(s): Later control or analytics action

Purpose: Use the report for handover, optimization, or analysis.

State or context change: The result becomes input to the next control step.

Note: This page stops before the later action becomes a separate procedure.

Important Messages

Message	Protocol	Direction	Purpose in this procedure	What to inspect briefly
Measurement Report	RRC	UE -> eNB	Carries the connected-mode measurement result.	Inspect measurement identity, target identity, event result, and timing.
Measurement Control	RRC	eNB -> UE	Defines the rule that made the report possible.	Check the configuration that produced the report.

Important Parameters to Inspect

Parameter	What it is	Where it appears	Why it matters	Common issues
Measurement identity	Identifies which configured report rule was used.	Measurement Report	Links the result back to the correct configuration.	The report is mapped to the wrong configuration entry.
Reported target	Cell, frequency, or RAT named by the result.	Measurement Report	Shows what the UE actually observed.	The target is assumed incorrectly from later mobility only.
Trigger timing	When the report appeared relative to the radio condition.	Measurement Report and surrounding trace timing	Important for early or late mobility analysis.	A valid report is treated as wrong because its timing was not checked.
Serving context	The UE radio condition at the time of reporting.	Trace around the report	Helps explain why the report became true.	The reported target is read without the serving context.
Report repetition pattern	Whether the same result repeated or oscillated.	Multiple reports in one trace	Useful for detecting instability before later mobility.	Repeated reporting is mistaken for a single isolated trigger.

Successful Completion

Success means Measurement Report appears with the expected identity, target context, and timing for the configured scenario.

Common Failures and Troubleshooting

Symptom	Likely cause	Where to inspect	Relevant message(s)	Relevant interface(s)	Likely next step
Report missing	The trigger was never satisfied, the configuration is wrong, or the trace does not include the needed interval.	Configuration plus the expected event window.	Measurement Report	LTE Uu	Check the active report rule before assuming the UE failed to report.
Report present but later action looks wrong	The report itself is valid, but the later interpretation or target selection is incorrect.	Measurement Report versus the later control branch.	Measurement Report	LTE Uu	Separate report correctness from later decision correctness.

What to Check in Logs and Traces

Read Measurement Report together with the earlier Measurement Control.
Confirm the reported identity and target before linking the report to later mobility.
Check whether repeated reporting shows instability before the later control action.

Related sub-procedures

Related message reference pages

Related troubleshooting pages

Notes

Measurement Reporting is the result-delivery stage. It explains how the UE returns the configured radio observation to the eNB.

FAQ

What is LTE Measurement Reporting?

It is the general procedure in which the UE sends Measurement Report after the configured trigger becomes true.

Does this page replace the event pages?

No. This page explains the generic reporting path, while the event pages explain individual trigger meanings.