ETSI TS 138 322 V17.1.0 (2022-08)

5G ; NR; Radio Link Control (RLC) protocol specification (3GPP TS 38.322 version 17.1.0 Release 17)

RTS/TSGR-0238322vh10

General Information

• Status: Not Published
• Technical Committee: 3GPP RAN 2 - Radio layer 2 specification and Radio layer 3 RR specification
• Current Stage: 12 - Citation in the OJ (auto-insert)
• Completion Date: 17-Aug-2022

Standards Content (Sample)

ETSI TS 138 322 V17.1.0 (2022-08)






TECHNICAL SPECIFICATION
5G;
NR;
Radio Link Control (RLC) protocol specification
(3GPP TS 38.322 version 17.1.0 Release 17)

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3GPP TS 38.322 version 17.1.0 Release 17 1 ETSI TS 138 322 V17.1.0 (2022-08)

Reference
RTS/TSGR-0238322vh10
Keywords
5G
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ETSI

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3GPP TS 38.322 version 17.1.0 Release 17 2 ETSI TS 138 322 V17.1.0 (2022-08)
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ETSI

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3GPP TS 38.322 version 17.1.0 Release 17 3 ETSI TS 138 322 V17.1.0 (2022-08)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Definitions, symbols and abbreviations . 6
3.1 Definitions . 6
3.2 Abbreviations . 7
4 General . 7
4.1 Introduction . 7
4.2 RLC architecture . 7
4.2.1 RLC entities . 7
4.2.1.1 TM RLC entity . 9
4.2.1.1.1 General . 9
4.2.1.1.2 Transmitting TM RLC entity . 9
4.2.1.1.3 Receiving TM RLC entity . 9
4.2.1.2 UM RLC entity . 9
4.2.1.2.1 General . 9
4.2.1.2.2 Transmitting UM RLC entity . 10
4.2.1.2.3 Receiving UM RLC entity . 10
4.2.1.3 AM RLC entity . 10
4.2.1.3.1 General . 10
4.2.1.3.2 Transmitting side . 11
4.2.1.3.3 Receiving side . 12
4.3 Services . 12
4.3.1 Services provided to upper layers . 12
4.3.2 Services expected from lower layers . 12
4.4 Functions . 12
5 Procedures . 13
5.1 RLC entity handling . 13
5.1.1 RLC entity establishment . 13
5.1.2 RLC entity re-establishment . 13
5.1.3 RLC entity release . 13
5.2 Data transfer procedures . 13
5.2.1 TM data transfer . 13
5.2.1.1 Transmit operations . 13
5.2.1.1.1 General . 13
5.2.1.2 Receive operations . 14
5.2.1.2.1 General . 14
5.2.2 UM data transfer . 14
5.2.2.1 Transmit operations . 14
5.2.2.1.1 General . 14
5.2.2.2 Receive operations . 14
5.2.2.2.1 General . 14
5.2.2.2.2 Actions when an UMD PDU is received from lower layer . 14
5.2.2.2.3 Actions when an UMD PDU is placed in the reception buffer . 15
5.2.2.2.4 Actions when t-Reassembly expires . 15
5.2.3 AM data transfer . 16
5.2.3.1 Transmit operations . 16
5.2.3.1.1 General . 16
5.2.3.2 Receive operations . 16
5.2.3.2.1 General . 16
ETSI

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3GPP TS 38.322 version 17.1.0 Release 17 4 ETSI TS 138 322 V17.1.0 (2022-08)
5.2.3.2.2 Actions when an AMD PDU is received from lower layer . 17
5.2.3.2.3 Actions when an AMD PDU is placed in the reception buffer . 17
5.2.3.2.4 Actions when t-Reassembly expires . 18
5.3 ARQ procedures . 18
5.3.1 General . 18
5.3.2 Retransmission . 18
5.3.3 Polling . 19
5.3.3.1 General . 19
5.3.3.2 Transmission of a AMD PDU . 19
5.3.3.3 Reception of a STATUS report . 20
5.3.3.4 Expiry of t-PollRetransmit . 20
5.3.4 Status reporting . 20
5.4 SDU discard procedures . 21
5.5 Data volume calculation . 21
5.6 Handling of unknown, unforeseen and erroneous protocol data . 22
5.6.1 Reception of PDU with reserved or invalid values . 22
6 Protocol data units, formats and parameters . 22
6.1 Protocol data units . 22
6.1.1 General . 22
6.1.2 RLC data PDU . 22
6.1.3 RLC control PDU . 22
6.2 Formats and parameters . 22
6.2.1 General . 22
6.2.2 Formats . 22
6.2.2.1 General . 22
6.2.2.2 TMD PDU . 23
6.2.2.3 UMD PDU . 23
6.2.2.4 AMD PDU . 24
6.2.2.5 STATUS PDU . 25
6.2.3 Parameters. 27
6.2.3.1 General . 27
6.2.3.2 Data field . 27
6.2.3.3 Sequence Number (SN) field . 27
6.2.3.4 Segmentation Info (SI) field . 27
6.2.3.5 Segment Offset (SO) field . 27
6.2.3.6 Data/Control (D/C) field . 28
6.2.3.7 Polling bit (P) field . 28
6.2.3.8 Reserved (R) field . 28
6.2.3.9 Control PDU Type (CPT) field . 28
6.2.3.10 Acknowledgement SN (ACK_SN) field . 28
6.2.3.11 Extension bit 1 (E1) field . 29
6.2.3.12 Negative Acknowledgement SN (NACK_SN) field . 29
6.2.3.13 Extension bit 2 (E2) field . 29
6.2.3.14 SO start (SOstart) field . 29
6.2.3.15 SO end (SOend) field . 29
6.2.3.16 Extension bit 3 (E3) field . 30
6.2.3.17 NACK range field . 30
7 Variables, constants and timers . 30
7.1 State variables . 30
7.2 Constants . 32
7.3 Timers . 32
7.4 Configurable parameters . 32
Annex A (informative): Change history . 33
History . 34

ETSI

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3GPP TS 38.322 version 17.1.0 Release 17 5 ETSI TS 138 322 V17.1.0 (2022-08)
Foreword
This Technical Specification has been produced by the 3rd Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
ETSI

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3GPP TS 38.322 version 17.1.0 Release 17 6 ETSI TS 138 322 V17.1.0 (2022-08)
1 Scope
The present document specifies the NR Radio Link Control (RLC) protocol for the UE – NR radio interface.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 38.300: "NR Overall Description; Stage 2".
[3] 3GPP TS 38.321: "NR MAC protocol specification".
[4] 3GPP TS 38.323: "NR PDCP specification".
[5] 3GPP TS 38.331: "NR RRC Protocol specification".
[6] 3GPP TS 23.287: "Architecture enhancements for 5G System (5GS) to support Vehicle-to-
Everything (V2X) services".
[7] 3GPP TS 38.340: "NR; Backhaul Adaptation Protocol (BAP) specification".
[8] 3GPP TS 23.304: "Proximity based Services (ProSe) in the 5G System (5GS)".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in TR 21.905 [1] and the following apply. A
term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905 [1].
Data field element: An RLC SDU or an RLC SDU segment that is mapped to the Data field.
NR sidelink communication: AS functionality enabling at least V2X Communication as defined in TS 23.287 [6] and
ProSe communication (including ProSe Relay) as defined in TS 23.304 [8], between two or more nearby UEs, using NR
technology but not traversing any network node.
RLC data volume: The amount of data available for transmission in an RLC entity.
RLC SDU segment: A segment of an RLC SDU.
Sidelink discovery: AS functionality enabling 5G ProSe UE-to-Network Relay Discovery or 5G ProSe Direct
Discovery as defined in TS 23.304 [8], using NR technology but not traversing any network node.
ETSI

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3GPP TS 38.322 version 17.1.0 Release 17 7 ETSI TS 138 322 V17.1.0 (2022-08)
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply. An
abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in
TR 21.905 [1].
AM Acknowledged Mode
AMD AM Data
ARQ Automatic Repeat request
gNB NR Node B
MBS Multicast/Broadcast Services
MCCH MBS Control Channel
MTCH MBS Traffic Channel
PDU Protocol Data Unit
RLC Radio Link Control
SBCCH Sidelink Broadcast Control Channel
SCCH Sidelink Control Channel
SDU Service Data Unit
SN Sequence Number
STCH Sidelink Traffic Channel
TB Transport Block
TM Transparent Mode
TMD TM Data
UE User Equipment
UM Unacknowledged Mode
UMD UM Data
4 General
4.1 Introduction
The objective is to describe the RLC architecture and the RLC entities from a functional point of view.
4.2 RLC architecture
4.2.1 RLC entities
The description in this clause is a model and does not specify or restrict implementations.
RRC is generally in control of the RLC configuration.
Functions of the RLC sub layer are performed by RLC entities. For an RLC entity configured at the gNB, there is a peer
RLC entity configured at the UE and vice versa. In NR sidelink communication, in sidelink discovery, for an RLC
entity configured at the transmitting UE, there is a peer RLC entity configured at each receiving UE.
An RLC entity receives/delivers RLC SDUs from/to upper layer and sends/receives RLC PDUs to/from its peer RLC
entity via lower layers.
An RLC PDU can either be an RLC data PDU or an RLC control PDU. If an RLC entity receives RLC SDUs from
upper layer, it receives them through a single RLC channel between RLC and upper layer, and after forming RLC data
PDUs from the received RLC SDUs, the RLC entity submits the RLC data PDUs to lower layer through a single logical
channel. If an RLC entity receives RLC data PDUs from lower layer, it receives them through a single logical channel,
and after forming RLC SDUs from the received RLC data PDUs, the RLC entity delivers the RLC SDUs to upper layer
through a single RLC channel between RLC and upper layer. If an RLC entity submits/receives RLC control PDUs
to/from lower layer, it submits/receives them through the same logical channel it submits/receives the RLC data PDUs
through.
ETSI

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3GPP TS 38.322 version 17.1.0 Release 17 8 ETSI TS 138 322 V17.1.0 (2022-08)
NOTE 1: In case the upper layer is BAP as defined in TS 38.340 [7], an RLC channel refers to a Backhaul RLC
channel.
An RLC entity can be configured to perform data transfer in one of the following three modes: Transparent Mode (TM),
U
...