5G NR - System Information Block 10 (SIB10)

Message Fact Sheet

Protocol	rrc	Network	5g
Spec	3GPP TS 38.331	Spec Section	5.2.1, 5.2.2, 6.3.1
Direction	gNB -> UE	Message Type	Broadcast System Information

Full message name	5G NR - System Information Block 10 (SIB10)
Protocol	RRC
Technology	5G
Direction	gNB -> UE
Interface	Uu
Signaling bearer / channel	Broadcast transport / BCCH-DL-SCH
Typical trigger	Broadcast by the cell as additional system information when non-public network identities from SIB1 are associated with human-readable network names.
Main purpose	Provides user-friendly NPN naming information so the UE and upper layers can present or use human-readable network names associated with the NPN identities broadcast in SIB1.
Main specification	3GPP TS 38.331, 5.2.1, 5.2.2, 6.3.1
Release added	Release 16
Procedures where used	System Information Acquisition, NPN Discovery, Manual Network Selection, Idle Operation
Related timers	SIB10 does not use a dedicated UE-specific transaction timer, Interpretation depends on SI acquisition timing and the validity of the NPN information already available from SIB1
Related cause values	SIB10 does not carry reject causes, Problems are usually inferred from missing acquisition, mismatched HRNN mapping, or wrong network-name presentation for an NPN

What is System Information Block 10 (SIB10) in simple terms?

System Information Block 10 (SIB10) is an NR broadcast system information block used to carry the Human-Readable Network Names (HRNN) of NPNs listed in SIB1.

Provides user-friendly NPN naming information so the UE and upper layers can present or use human-readable network names associated with the NPN identities broadcast in SIB1.

Why this message matters

SIB10 is the 5G NR broadcast block that mainly gives human-readable names for private networks already identified in SIB1.

Where this message appears in the call flow

System Information Acquisition

Call flow position: Read as additional broadcast information after the essential access layer is already available.

Typical state: UE is camped and expanding the broadcast-information context beyond access and mobility.

Preconditions:

MIB and SIB1 have been acquired.
SIB1 contains NPN-related identities that may be associated with HRNN.
The UE knows the scheduling for additional system information.

Next likely message: UE maps SIB10 HRNN information to the NPN identities already learned from SIB1

NPN Discovery / Selection

Call flow position: Used when the UE needs a human-readable name for an NPN candidate already advertised in SIB1.

Typical state: UE is not necessarily in a dedicated UE-specific RRC transaction.

Preconditions:

The network broadcasts NPN-related identities in SIB1.
The network also broadcasts SIB10.

Next likely message: Upper layer or UI uses HRNN for manual selection, display, or validation

Manual Network Selection Support

Call flow position: Provides human-readable naming context for network selection workflows.

Typical state: UE may be idle, camped, or otherwise using valid broadcast SI.

Preconditions:

SIB10 has been acquired successfully.

Next likely message: No direct RRC next message is required; the information is consumed locally or forwarded upward

Call flow position

Previous message(s): MIB, System Information Block 1 (SIB1), NPN identity information from SIB1

Next message(s): Manual network selection support, UE / upper-layer use of HRNN, Later access and service behavior using the identified NPN

Message direction and transport

Sender and receiver: gNB -> UE

Interface: Uu

Domain: Access-side radio control and broadcast system information

Signaling bearer: Broadcast transport

Logical channel: BCCH-DL-SCH

Transport / encapsulation: RRC system information carried on BCCH-DL-SCH after the UE has acquired the essential system information and the scheduling for additional SI

Security context: Broadcast information. It is cell-common and not protected by dedicated AS security.

Message Structure Overview

SIB10 is not mainly about access, mobility, or timing. Its practical purpose is NPN naming.
For engineering work, the main question is whether the HRNN information aligns correctly with the NPN identities already provided in SIB1.
SIB10 becomes especially important when manual network selection, NPN discovery, or displayed private-network naming does not match expectations.

ASN.1 for 5G NR - System Information Block 10 (SIB10)

BCCH-DL-SCH-Message ::= SEQUENCE {
  message CHOICE {
    c1 CHOICE {
      systemInformationBlockType1 SystemInformationBlockType1,
      systemInformation          SystemInformation,
      ...
    },
    ...
  }
}

SystemInformation ::= SEQUENCE {
  criticalExtensions CHOICE {
    systemInformation SystemInformation-IEs,
    ...
  }
}

SystemInformation-IEs ::= SEQUENCE {
  sib-TypeAndInfo SEQUENCE (SIZE (1..maxSIB)) OF CHOICE {
    sib10 SystemInformationBlockType10-r16,
    ...
  }
}

SystemInformationBlockType10-r16 ::= SEQUENCE {
  hrnn-List-r16   SEQUENCE (SIZE (1..maxNPN-r16)) OF HRNN-r16,
  ...
}

How to read this ASN.1

SIB10 is typically carried inside the broader SystemInformation container. The most important practical field is hrnn-List-r16, which provides the human-readable names of the NPNs already advertised in SIB1.

Decoded Message Dump

BCCH-DL-SCH-Message
  message: c1
    systemInformation
      criticalExtensions
        systemInformation
          sib-TypeAndInfo
            sib10
              hrnn-List-r16
                [0]
                  hrnn-r16: "Factory-Private-5G"
                [1]
                  hrnn-r16: "Warehouse-NPN"

How to read this dump

The key practical block is hrnn-List-r16.
Each HRNN entry is meaningful only when correlated with the corresponding NPN identity information already learned from SIB1.
If the network name shown to the user is wrong, the issue may be in the SIB1 identity mapping, in SIB10 HRNN content, or in how the UE correlates both.

Important Information Elements

IE	Required	Description
`hrnn-List-r16`	Yes	The core SIB10 payload. It carries the human-readable network names associated with NPN information broadcast elsewhere, typically in SIB1.
`HRNN-r16`	Optional	Individual human-readable network-name entry that represents one NPN label.
`mapping context to SIB1 NPN identities`	Optional	Operationally important relationship between the HRNN list in SIB10 and the NPN identities already broadcast in SIB1.
`display / selection-oriented naming content`	Optional	Useful for UI, manual selection, or upper-layer logic rather than low-level radio configuration.

Detailed field explanation

`hrnn-List-r16`

The core SIB10 payload. It carries the human-readable network names associated with NPN information broadcast elsewhere, typically in SIB1.

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.

`HRNN-r16`

Individual human-readable network-name entry that represents one NPN label.

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.

`mapping context to SIB1 NPN identities`

Operationally important relationship between the HRNN list in SIB10 and the NPN identities already broadcast in SIB1.

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.

`display / selection-oriented naming content`

Useful for UI, manual selection, or upper-layer logic rather than low-level radio configuration.

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 and SIB1 were decoded successfully before reviewing SIB10 behavior.
Verify that the UE actually acquired the additional SI carrying SIB10.
Check whether hrnn-List-r16 is present and complete.
Correlate SIB10 HRNN entries with the NPN identities and related selection information in SIB1.
If the wrong network name is shown, separate SIB10 broadcast content from UE UI or upper-layer display logic.
If manual NPN selection is wrong, compare the available HRNN entries with the actual list of NPN identities in SIB1.

Common Issues and Troubleshooting

The UE shows the wrong private network name.

Likely cause: SIB10 HRNN content may be wrong, missing, or mapped incorrectly to the SIB1 NPN identities.

What to inspect: Check hrnn-List-r16 and compare it with the NPN identities and order/context from SIB1.

Next step: Separate broadcast-content correctness from UI rendering correctness.

An NPN is visible in SIB1 but no readable network name is shown.

Likely cause: SIB10 may be missing, incomplete, or not acquired by the UE.

What to inspect: Check SI scheduling and whether the UE actually decoded SIB10.

Next step: Correlate SIB1 NPN identity availability with SIB10 acquisition timing.

Manual NPN selection is confusing or inconsistent.

Likely cause: The HRNN list may not align clearly with the underlying NPN identity set.

What to inspect: Check both SIB1 identity content and SIB10 HRNN content together.

Next step: Review the SIB1 and SIB10 pair as one NPN-discovery chain.

LTE / 5G / Variant Comparison

SIB10 versus SIB5 to SIB9

SIB5 to SIB9 focus on inter-RAT mobility or time information. SIB10 focuses on human-readable naming for NPNs.

SIB10 versus dedicated RRC

SIB10 is broadcast cell-common naming information, not UE-specific connected-mode configuration.

FAQ

What is SIB10 in 5G NR?

SIB10 is System Information Block 10, an NR broadcast block used mainly to carry the human-readable network names of NPNs listed in SIB1.

Who sends SIB10?

The gNB broadcasts SIB10 as additional system information.

What is the main purpose of SIB10?

To provide human-readable names for NPNs so the UE or upper layers can display or use them for selection.

On which channel is SIB10 sent?

SIB10 is carried in system information on BCCH-DL-SCH.

Why is SIB10 useful in troubleshooting?

Because it helps explain why a private network name is missing, wrong, or mismatched with the NPN identity advertised in SIB1.

Does SIB10 contain UE-specific information?

No. SIB10 is broadcast cell-common information.

Related message pages

Related Procedures

5G Initial Registration

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.