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LTE GNSS Measurement Reporting Call Flow

call-flow LTE | GNSS | Positioning | Measurements

LTE GNSS measurement reporting is the measurement procedure used when LTE collects GNSS-related positioning information from the UE for later positioning workflows.

This page focuses on the GNSS-linked reporting path rather than generic mobility events.

Introduction

The LTE side enables the GNSS-related reporting behavior, the UE performs the GNSS observation, and the measurement result is returned to the network for later positioning use.

Use this page when the trace includes GNSS-related measurement handling instead of ordinary neighbor-cell mobility reporting.

What Is GNSS Measurement Reporting in Simple Terms?

What starts the procedure: The network needs GNSS-related measurement information from the UE.
What the UE and network want to achieve: Collect GNSS-related results for later positioning handling.
What success looks like: The UE returns the expected GNSS-related measurement result.
What failure means: The GNSS-related result is missing, delayed, or not aligned with the requested positioning context.

Why this procedure matters

This page separates GNSS-linked reporting from ordinary LTE mobility events. It is useful when positioning is the real reason for the measurement activity.

Quick Fact Sheet

Procedure name	LTE GNSS Measurement Reporting
Domain	GNSS-related measurement reporting in LTE
Main trigger	The network requests GNSS-related observation and reporting
Start state	UE is connected with GNSS-related reporting setup active
End state	GNSS-related measurement result is available to the network
Main nodes	UE, eNB
Main protocols	RRC
Main success outcome	GNSS-related result is returned correctly
Main failure outcome	GNSS result is missing or unusable
Most important messages	GNSS-related reporting configuration and result delivery
Main specs	TS 36.331

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

Preconditions

GNSS-related measurement handling is relevant to the current scenario.
The UE is in connected LTE service.
The reporting setup for GNSS-related results is active.

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
|<--GNSS report config----|
|--GNSS result----------->|

Major Phases

Phase	What happens
1. GNSS setup	The network enables GNSS-related reporting behavior.
2. GNSS observation	The UE performs the required GNSS-related measurement handling.
3. GNSS report delivery	The UE returns the result to the LTE side.
4. Positioning use	The result is consumed by later positioning logic.

Step-by-Step Breakdown

Step 1: Configure GNSS-related reporting

Sender -> receiver: eNB -> UE

Message(s): GNSS-related measurement configuration

Purpose: Request the GNSS-linked result needed by the network.

State or context change: The UE starts the required GNSS observation handling.

Note: This page is positioning-oriented rather than mobility-oriented.

Step 2: Perform the GNSS observation

Sender -> receiver: UE

Message(s): GNSS measurement activity

Purpose: Generate the requested GNSS-related result.

State or context change: The UE has the GNSS measurement context needed for reporting.

Note: This is the core observation step behind the later report.

Step 3: Return the result

Sender -> receiver: UE -> eNB

Message(s): GNSS Measurement Report

Purpose: Send the GNSS-related outcome back to LTE.

State or context change: The LTE side now has the requested positioning-related result.

Note: The later positioning workflow is outside this page.

Step 4: Use the result later

Sender -> receiver: Network

Message(s): Positioning workflow continuation

Purpose: Consume the GNSS result in the relevant positioning logic.

State or context change: The report becomes an input to later non-call-flow processing.

Note: This page stops at the reporting stage.

Important Messages

Message	Protocol	Direction	Purpose in this procedure	What to inspect briefly
GNSS Measurement Report	RRC	UE -> eNB	Returns the GNSS-related result to LTE.	Check whether the GNSS-linked result matches the requested positioning context.
Measurement configuration	RRC	eNB -> UE	Activates the GNSS-related reporting behavior.	Check whether the scenario really requested GNSS-related reporting.

Important Parameters to Inspect

Parameter	What it is	Where it appears	Why it matters	Common issues
GNSS reporting scope	The positioning-related purpose behind the report.	Configuration	Explains why GNSS appears in the LTE trace.	GNSS activity is mistaken for generic radio measurement reporting.
Result timing	When the GNSS-related result appears relative to the setup.	Trace timing	Useful for delayed or missing-report analysis.	The result is marked late without checking the observation window.
GNSS result payload	The actual GNSS-related information returned by the UE.	GNSS Measurement Report	Shows whether the requested result was obtained.	The result is present but not aligned with the intended positioning use.
LTE correlation point	Where the GNSS result appears in the LTE trace.	Report delivery	Helps separate LTE signaling from later positioning use.	The later positioning branch is blamed before the LTE report is checked.
Requested context	The exact GNSS-related need of the network.	Configuration	Shows whether the reported result matches the original request.	Wrong request assumption.

Successful Completion

Success means the UE returns the requested GNSS-related result and the LTE side can use it in the intended positioning workflow.

Common Failures and Troubleshooting

Symptom	Likely cause	Where to inspect	Relevant message(s)	Relevant interface(s)	Likely next step
GNSS result missing	The requested GNSS-related observation was not completed or was not captured.	Configuration and the expected reporting interval.	GNSS Measurement Report	LTE Uu	Check whether the scenario actually supported the requested GNSS reporting path.

What to Check in Logs and Traces

Confirm that GNSS-related reporting was explicitly requested.
Check where the GNSS result appears in the LTE trace.
Separate LTE report delivery from the later positioning consumer workflow.

Related sub-procedures

Related message reference pages

Related troubleshooting pages

Notes

GNSS Measurement Reporting is positioning-oriented. The value of the page is in tracing the GNSS result back to the LTE reporting path.

FAQ

What is LTE GNSS Measurement Reporting?

It is the LTE reporting path used when the network collects GNSS-related measurement results from the UE.