LTE RRC SIB13 - System Information Block Type 13

Message Fact Sheet

Protocol	lte-rrc	Network	lte
Spec	3GPP TS 36.331	Spec Section	5.2.2, 5.2.4, 6.2.2
Direction	eNodeB -> UE	Message Type	Broadcast System Information

Full message name	LTE RRC SIB13 - System Information Block Type 13
Protocol	LTE-RRC
Technology	LTE
Direction	eNodeB -> UE
Interface	Uu
Signaling bearer / channel	Broadcast system information transport / BCCH mapped to DL-SCH
Typical trigger	The UE reads System Information carrying SIB13 when MBMS service support is relevant, during MBMS service discovery, MBMS monitoring preparation, system-information refresh, or other MBSFN-area analysis.
Main purpose	Provides the MBSFN area identity and notification configuration the UE needs before it can follow MBMS control signaling and receive MBMS services.
Main specification	3GPP TS 36.331, 5.2.2, 5.2.4, 6.2.2
Release added	Release 9
Procedures where used	System Information Acquisition, MBMS Service Discovery, MBMS Monitoring Preparation, Broadcast-Service Area Evaluation, System Information Change Notification

What is System Information Block Type 13 in simple terms?

Broadcast LTE RRC system information block carried inside System Information that provides MBMS and MBSFN area information used before MCCH reception.

Provides the MBSFN area identity and notification configuration the UE needs before it can follow MBMS control signaling and receive MBMS services.

Why this message matters

SIB13 is the LTE broadcast block that tells the UE which MBMS area context exists before MCCH reception.

Where this message appears in the call flow

LTE MBMS service discovery

Call flow position: Broadcast preparation step used after the UE already has the basic LTE system-information context and now needs MBMS area information.

Typical state: UE is camped on LTE and is checking whether the cell provides MBMS service context relevant to the requested service.

Preconditions:

MIB and the relevant LTE system-information scheduling context have already been acquired.
System Information containing SIB13 is present and decodable.

Next likely message: MCCH monitoring for the selected MBSFN area

LTE MBMS service acquisition

LTE MBMS acquisition flow showing SIB13 area information leading to MCCH monitoring for an announced MBSFN area — In LTE MBMS service acquisition, the UE uses SIB13 to identify the relevant MBSFN area and then continues toward MCCH monitoring.

Call flow position: MBMS setup step where the UE uses the SIB13 area context before moving to MBMS control-channel reading.

Typical state: UE is preparing to receive MBMS service information for an announced MBSFN area.

Preconditions:

The UE has identified that MBMS service in the cell is relevant.
SIB13 has been acquired successfully.

Next likely message: MCCH monitoring and MBMS control information acquisition

System information change handling

LTE system information change flow showing refreshed System Information carrying SIB13 and continued MBMS monitoring with updated area data — When system information changes, the UE refreshes SIB13 so that later MBMS monitoring follows the updated MBSFN area and MCCH assumptions.

Call flow position: Refresh step where the UE reacquires SIB13 because MBMS area or notification assumptions may have changed.

Typical state: UE must refresh stored MBMS broadcast assumptions before continuing to rely on them.

Preconditions:

A system-information refresh was triggered.
Refreshed LTE system-information scheduling context is available.

Next likely message: Continued MBMS monitoring using refreshed SIB13 data

Call flow position

Previous message(s): MasterInformationBlock, SystemInformationBlockType1, SystemInformation

Next message(s): MCCH monitoring for the selected MBSFN area, Idle continuation without MBMS reception, MBMS service acquisition using the announced area context

Message direction and transport

Sender and receiver: eNodeB -> UE

Interface: Uu

Domain: Access-side radio control for LTE MBMS broadcast-service preparation

Signaling bearer: Broadcast system information transport

Logical channel: BCCH mapped to DL-SCH

Transport / encapsulation: System Information carried on BCCH and transmitted on DL-SCH with SIB13 included in sib-TypeAndInfo

Security context: Broadcast message with no dedicated SRB or AS security. The UE reads it after the LTE broadcast context and before MBMS control-channel use.

Message Structure Overview

System Information Block Type 13 extends LTE broadcast reading into MBMS and MBSFN service preparation.
Its practical meaning comes from which MBSFN areas are advertised and how the UE should interpret MBMS notification behavior before reading MCCH.
In troubleshooting, SIB13 is most useful when the question is whether the cell announced the MBMS area and control context needed for later MBMS reception.

ASN.1 for LTE RRC SIB13 - System Information Block Type 13

SystemInformationBlockType13-r9 ::= SEQUENCE {
  mbsfn-AreaInfoList-r9        MBSFN-AreaInfoList-r9,
  notificationConfig-r9        MBMS-NotificationConfig-r9 OPTIONAL,
  lateNonCriticalExtension     OCTET STRING OPTIONAL,
  nonCriticalExtension         SystemInformationBlockType13-v920-IEs OPTIONAL
}

MBSFN-AreaInfoList-r9 ::= SEQUENCE (SIZE (1..maxMBSFN-Area)) OF MBSFN-AreaInfo-r9

MBSFN-AreaInfo-r9 ::= SEQUENCE {
  mbsfn-AreaId-r9              INTEGER (0..255),
  non-MBSFNregionLength        ENUMERATED {s1, s2},
  notificationIndicator-r9     BOOLEAN,
  mcch-RepetitionPeriod-r9     ENUMERATED {rf32, rf64, rf128, rf256},
  mcch-Offset-r9               INTEGER (0..10),
  mcch-ModificationPeriod-r9   ENUMERATED {rf512, rf1024},
  sf-AllocInfo-r9              BIT STRING (SIZE (6)),
  signallingMCS-r9             ENUMERATED {n2, n7, n13, n19}
}

How to read this ASN.1

This page focuses on the stable SIB13 reading model used in practice: which MBSFN areas are advertised, whether notification is enabled, and what MCCH scheduling context follows.

LTE RRC SIB13 - System Information Block Type 13 - Example Dump

BCCH-DL-SCH-Message
  message c1 : systemInformation : {
    criticalExtensions systemInformation-r8 : {
      sib-TypeAndInfo {
        sib13-v920 {
          mbsfn-AreaInfoList-r9 {
            {
              mbsfn-AreaId-r9 3,
              non-MBSFNregionLength s2,
              notificationIndicator-r9 TRUE,
              mcch-RepetitionPeriod-r9 rf64,
              mcch-Offset-r9 2,
              mcch-ModificationPeriod-r9 rf512,
              sf-AllocInfo-r9 '101010'B,
              signallingMCS-r9 n7
            }
          }
        }
      }
    }
  }

How to read this dump

The first useful question is whether the cell actually advertises SIB13 and which MBSFN areas appear in the list.
If MBMS reception did not progress, verify that the announced area and MCCH timing assumptions match the observed behavior.
If MBMS behavior changed after a refresh, compare the old and new MBSFN area data before assuming a receiver issue.

Important Information Elements

IE	Required	Description
`mbsfn-AreaInfoList`	Yes	List of MBSFN area descriptions advertised by the cell for MBMS operation.
`notificationConfig`	Optional	MBMS notification configuration used when the cell supports notification behavior for MBMS.
`lateNonCriticalExtension`	Optional	Late extension branch for later release additions.
`nonCriticalExtension`	Optional	Release-extension branch used for newer MBMS additions.

Detailed field explanation

`mbsfn-AreaInfoList`

List of MBSFN area descriptions advertised by the cell for MBMS operation.

Presence: Required

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

`notificationConfig`

MBMS notification configuration used when the cell supports notification behavior for MBMS.

Presence: Optional

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

`lateNonCriticalExtension`

Late extension branch for later release additions.

Presence: Optional

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

`nonCriticalExtension`

Release-extension branch used for newer MBMS additions.

Presence: Optional

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

What to check in logs and traces

Confirm MIB, SIB1, and the relevant System Information scheduling context were acquired before interpreting SIB13.
Check whether SIB13 is present in the relevant System Information message.
Inspect the MBSFN area identities and confirm the expected MBMS area is actually announced.
Inspect notificationIndicator, MCCH repetition period, MCCH offset, and MCCH modification period.
Correlate SIB13 with later MCCH behavior when explaining MBMS service availability.

Common Issues and Troubleshooting

The UE does not proceed toward MBMS control reception.

Likely cause: The expected MBSFN area may not be advertised in SIB13, or the MCCH scheduling context may differ from the assumption.

What to inspect: Check mbsfn-AreaInfoList, notificationIndicator, mcch-RepetitionPeriod, and mcch-Offset.

Next step: Validate the SIB13 MBMS area announcement before treating the issue as an MCCH problem.

MBMS service appears available on one cell but not another.

Likely cause: The cells may advertise different MBSFN area sets or different MCCH scheduling assumptions.

What to inspect: Compare the SIB13 content from the working and non-working cells.

Next step: Use SIB13 as the first comparison point before moving deeper into MCCH details.

MBMS behavior changed after a system-information refresh.

Likely cause: The refreshed SIB13 may have updated area identities, notification behavior, or MCCH timing.

What to inspect: Compare the old and new SIB13 content and correlate the changed values with the new MBMS outcome.

Next step: Treat it as a broadcast MBMS context change until proven otherwise.

LTE / 5G / Variant Comparison

Compared with System Information

System Information is the broadcast container message. SIB13 is the MBMS and MBSFN payload inside that container.

Compared with Master Information Block

MIB starts the LTE broadcast reading path. SIB13 appears much later when the question is specifically about MBMS service preparation.

Compared with MCCH

SIB13 announces MBMS area and control-channel context. MCCH then carries the later MBMS control information for that area.

FAQ

What is System Information Block Type 13 in LTE?

It is the LTE broadcast block that gives the UE MBMS and MBSFN area information before MCCH reception.

Why is LTE SIB13 important?

Because it often explains whether the cell actually announced the MBMS area and control context needed for service reception.

What should I inspect first in LTE SIB13?

Start with the MBSFN area list, then inspect notification and MCCH timing values.

How does SIB13 relate to MCCH?

SIB13 gives the UE the MBMS area and scheduling context. MCCH carries the later MBMS control information for that area.

Related message pages

Related Procedures

Related Tools

Use This Reference in Practice

Decode this message with the 3GPP Decoder, inspect the related message database, or open the matching call flow to see where this signaling step fits in the full procedure.