ETSI TS 137 213 V17.6.0 (2023-06)

LTE; 5G; Physical layer procedures for shared spectrum channel access (3GPP TS 37.213 version 17.6.0 Release 17)

RTS/TSGR-0137213vh60

General Information

• Status: Not Published
• Technical Committee: 3GPP RAN 1 - Radio layer 1 specification
• Current Stage: 8 - TB approval
• Completion Date: 14-Jun-2023

Standards Content (Sample)

ETSI TS 137 213 V17.6.0 (2023-07)
TECHNICAL SPECIFICATION
LTE;
5G;
Physical layer procedures for shared spectrum channel access
(3GPP TS 37.213 version 17.6.0 Release 17)
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3GPP TS 37.213 version 17.6.0 Release 17 1 ETSI TS 137 213 V17.6.0 (2023-07)
Reference
RTS/TSGR-0137213vh60
Keywords
5G,LTE
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ETSI
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3GPP TS 37.213 version 17.6.0 Release 17 2 ETSI TS 137 213 V17.6.0 (2023-07)
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ETSI
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3GPP TS 37.213 version 17.6.0 Release 17 3 ETSI TS 137 213 V17.6.0 (2023-07)
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 Symbols .............................................................................................................................................................. 6

3.3 Abbreviations ..................................................................................................................................................... 7

4 Channel access procedure ........................................................................................................................ 7

4.0 General ............................................................................................................................................................... 7

4.1 Downlink channel access procedures ................................................................................................................. 8

4.1.1 Type 1 DL channel access procedures .......................................................................................................... 8

4.1.1.1 Regional limitations on channel occupancy time .................................................................................... 9

4.1.2 Type 2 DL channel access procedures .......................................................................................................... 9

4.1.2.1 Type 2A DL channel access procedures ............................................................................................... 10

4.1.2.2 Type 2B DL channel access procedures ................................................................................................ 10

4.1.2.3 Type 2C DL channel access procedures ................................................................................................ 10

4.1.3 DL channel access procedures in a shared channel occupancy................................................................... 10

4.1.4 Contention window adjustment procedures ................................................................................................ 11

4.1.4.1 Contention window adjustment procedures for transmissions by eNB ................................................. 11

4.1.4.2 Contention window adjustment procedures for DL transmissions by gNB .......................................... 12

4.1.4.3 Common procedures for CWS adjustments for DL transmissions ........................................................ 13

4.1.5 Energy detection threshold adaptation procedures ..................................................................................... 13

4.1.6 Channel access procedures for transmission(s) on multiple channels ........................................................ 14

4.1.6.1 Type A multi-channel access procedures .............................................................................................. 14

4.1.6.1.1 Type A1 multi-channel access procedures ...................................................................................... 14

4.1.6.1.2 Type A2 multi-channel access procedures ...................................................................................... 14

4.1.6.2 Type B multi-channel access procedure ................................................................................................ 14

4.1.6.2.1 Type B1 multi-channel access procedure ........................................................................................ 15

4.1.6.2.2 Type B2 multi-channel access procedure ........................................................................................ 15

4.2 Uplink channel access procedures .................................................................................................................... 15

4.2.1 Channel access procedures for uplink transmission(s) ............................................................................... 16

4.2.1.0 Channel access procedures and UL related signaling ........................................................................... 17

4.2.1.0.0 Channel access procedures upon detection of a common DCI ........................................................ 17

4.2.1.0.1 Channel access procedures for consecutive UL transmission(s) ..................................................... 18

4.2.1.0.2 Conditions for maintaining Type 1 UL channel access procedures ................................................. 19

4.2.1.0.3 Conditions for indicating Type 2 channel access procedures .......................................................... 20

4.2.1.0.4 Channel access procedures for UL multi-channel transmission(s) .................................................. 20

4.2.1.1 Type 1 UL channel access procedure .................................................................................................... 21

4.2.1.2 Type 2 UL channel access procedure .................................................................................................... 22

4.2.1.2.1 Type 2A UL channel access procedure ........................................................................................... 22

4.2.1.2.2 Type 2B UL channel access procedure............................................................................................ 22

4.2.1.2.3 Type 2C UL channel access procedure............................................................................................ 22

4.2.2 Contention window adjustment procedures ................................................................................................ 22

4.2.2.1 Contention window adjustment procedures for UL transmissions scheduled/configured by eNB ....... 22

4.2.2.2 Contention window adjustment procedures for UL transmissions scheduled/configured by gNB ....... 24

4.2.2.3 Common procedures for CWS adjustments for UL transmissions ........................................................ 25

4.2.3 Energy detection threshold adaptation procedure ....................................................................................... 25

4.2.3.1 Default maximum energy detection threshold computation procedure ................................................. 25

4.3 Channel access procedures for semi-static channel occupancy ........................................................................ 26

4.3.1 Channel access procedures to initiate a channel occupancy ....................................................................... 26

4.3.1.1 Channel occupancy initiated only by gNB ............................................................................................ 27

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3GPP TS 37.213 version 17.6.0 Release 17 4 ETSI TS 137 213 V17.6.0 (2023-07)

4.3.1.2 Channel occupancy initiated by gNB or UE ......................................................................................... 27

4.3.1.2.1 Channel occupancy initiated by gNB and sensing procedures ........................................................ 27

4.3.1.2.2 Channel occupancy initiated by UE and sensing procedures .......................................................... 28

4.3.1.2.3 Association with initiated channel occupancy for configured UL transmissions ............................ 28

4.3.1.2.4 Association with initiated channel occupancy for scheduled UL transmissions ............................. 30

4.3.1.2.4.1 Intra-period scheduled UL transmissions................................................................................... 30

4.3.1.2.4.2 Cross-period scheduled UL transmissions ................................................................................. 30

4.3.2 Channel access related procedures for UL transmissions ........................................................................... 31

4.3.3 Channel access procedures for transmission(s) on multiple channels ........................................................ 32

4.4 Channel access procedures for frequency range 2-2 ........................................................................................ 32

4.4.1 Type 1 channel access procedures .............................................................................................................. 34

4.4.2 Type 2 channel access procedures .............................................................................................................. 35

4.4.3 Type 3 channel access procedures .............................................................................................................. 35

4.4.4 Channel access procedures in an initiated channel occupancy ................................................................... 35

4.4.5 Exempted transmissions from sensing ........................................................................................................ 36

4.4.6 Channel access procedures for transmission(s) on multiple channels or beams ......................................... 36

4.4.7 Energy detection threshold adaptation procedures ..................................................................................... 36

Annex X (informative): Change history ............................................................................................... 37

History .............................................................................................................................................................. 40

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3GPP TS 37.213 version 17.6.0 Release 17 5 ETSI TS 137 213 V17.6.0 (2023-07)
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 37.213 version 17.6.0 Release 17 6 ETSI TS 137 213 V17.6.0 (2023-07)
1 Scope

The present document specifies and establishes the characteristics of the physical layer procedures for shared spectrum

channel.
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 36.104: "Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS)

radio transmission and reception".

[3] 3GPP TS 36.101: "Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE)

radio transmission and reception".

[4] 3GPP TS 36.213: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer

procedures".

[5] 3GPP TS 36.212: "Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel

coding".
[6] 3GPP TS 38.104: "NR; Base Station (BS) radio transmission and reception".
[7] 3GPP TS 38.213: "NR; Physical layer procedures for control".
[8] 3GPP TS 38.214: "NR; Physical layer procedures for data".
[9] 3GPP TS 38.300: "NR; NR and NG-RAN Overall Description; Stage 2".
[10] 3GPP TS 38.212: "NR; Multiplexing and channel coding".
[11] 3GPP TS 38.211: "NR; Physical channels and Modulations".
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] apply. A term defined in the

present document takes precedence over the definition of the same term, if any, in TR 21.905 [1].

3.2 Symbols
For the purposes of the present document, the following symbols apply:
CW Contention window for a given priority class
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3GPP TS 37.213 version 17.6.0 Release 17 7 ETSI TS 137 213 V17.6.0 (2023-07)
CW Maximum contention window for a given priority class
max, p
CW Minimum contention window for a given priority class
min,p
T Maximum channel occupancy time for a given priority class
mcot,p
T Maximum Uplink channel occupancy time for a given priority class
ulmcot, p
X Energy detection threshold
Thresh
X Maximum energy detection threshold
Thresh_max
3.3 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].
AUL-DFI Autonomous UL Downlink feedback indication
CAPC Channel access priority class
COT Channel Occupancy Time
LAA Licensed Assisted Access
MCOT Maximum Channel Occupancy Time
4 Channel access procedure
4.0 General

Unless otherwise noted, the definitions below are applicable for the following terminologies used in this specification:

- A channel refers to a carrier or a part of a carrier consisting of a contiguous set of resource blocks (RBs) on

which a channel access procedure is performed in shared spectrum.

- A channel access procedure is a procedure based on sensing that evaluates the availability of a channel for

performing transmissions. The basic unit for sensing is a sensing slot with a duration � =9��. The sensing slot

duration � is considered to be idle if an eNB/gNB or a UE senses the channel during the sensing slot duration,

and determines that the detected power for at least 4�� within the sensing slot duration is less than energy

detection threshold � . Otherwise, the sensing slot duration � is considered to be busy.

Thresh ��

- A channel occupancy refers to transmission(s) on channel(s) by eNB/gNB/UE(s) after performing the

corresponding channel access procedures in this clause.

- A Channel Occupancy Time refers to the total time for which eNB/gNB/UE and any eNB/gNB/UE(s) sharing

the channel occupancy perform transmission(s) on a channel after an eNB/gNB/UE performs the corresponding

channel access procedures described in this clause. For determining a Channel Occupancy Time, if a

transmission gap is less than or equal to 25��, the gap duration is counted in the channel occupancy time. A

channel occupancy time can be shared for transmission between an eNB/gNB and the corresponding UE(s).

- A DL transmission burst is defined as a set of transmissions from an eNB/gNB without any gaps greater than

16��. Transmissions from an eNB/gNB separated by a gap of more than 16�� are considered as separate DL

transmission bursts. An eNB/gNB can transmit transmission(s) after a gap within a DL transmission burst

without sensing the corresponding channel(s) for availability.

- A UL transmission burst is defined as a set of transmissions from a UE without any gaps greater than 16��.

Transmissions from a UE separated by a gap of more than 16�s are considered as separate UL transmission

bursts. A UE can transmit transmission(s) after a gap within a UL transmission burst without sensing the

corresponding channel(s) for availability.

- A discovery burst refers to a DL transmission burst including a set of signal(s) and/or channel(s) confined within

a window and associated with a duty cycle. The discovery burst can be any of the following:

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3GPP TS 37.213 version 17.6.0 Release 17 8 ETSI TS 137 213 V17.6.0 (2023-07)

- Transmission(s) initiated by an eNB that includes a primary synchronization signal (PSS), secondary

synchronization signal (SSS) and cell-specific reference signal(s)(CRS) and may include non-zero power CSI

reference signals (CSI-RS).

- Transmission(s) initiated by a gNB that includes at least an SS/PBCH block consisting of a primary

synchronization signal (PSS), secondary synchronization signal (SSS), physical broadcast channel (PBCH)

with associated demodulation reference signal (DM-RS) and may also include CORESET for PDCCH

scheduling PDSCH with SIB1, and PDSCH carrying SIB1 and/or non-zero power CSI reference signals

(CSI-RS).
4.1 Downlink channel access procedures

An eNB operating LAA Scell(s) on channel(s) and a gNB performing transmission(s) on channel(s) shall perform the

channel access procedures described in this clause for accessing the channel(s) on which the transmission(s) are

performed.

In this clause, � for sensing is adjusted as described in clause 4.1.5 when applicable.

������

A gNB performs channel access procedures in this clause unless the higher layer parameter channelAccessMode-r16 is

provided and channelAccessMode-r16 ='semiStatic'.
4.1.1 Type 1 DL channel access procedures

This clause describes channel access procedures to be performed by an eNB/gNB where the time duration spanned by

the sensing slots that are sensed to be idle before a downlink transmission(s) is random. The clause is applicable to the

following transmissions:
- Transmission(s) initiated by an eNB including PDSCH/PDCCH/EPDCCH, or
- Any transmission(s) initiated by a gNB.

The eNB/gNB may transmit a transmission after first sensing the channel to be idle during the sensing slot durations of

a defer duration � and after the counter � is zero in step 4. The counter � is adjusted by sensing the channel for

additional sensing slot duration(s) according to the steps below:

1) set � =� , where � is a random number uniformly distributed between 0 and �� , and go to step 4;

���� ���� �
2) if � >0 and the eNB/gNB chooses to decrement the counter, set � =� −1;

3) sense the channel for an additional sensing slot duration, and if the additional sensing slot duration is idle, go to

step 4; else, go to step 5;
4) if � =0, stop; else, go to step 2.

5) sense the channel until either a busy sensing slot is detected within an additional defer duration � or all the

sensing slots of the additional defer duration � are detected to be idle;

6) if the channel is sensed to be idle during all the sensing slot durations of the additional defer duration � , go to

step 4; else, go to step 5;

If an eNB/gNB has not transmitted a transmission after step 4 in the procedure above, the eNB/gNB may transmit a

transmission on the channel, if the channel is sensed to be idle at least in a sensing slot duration � when the eNB/gNB

is ready to transmit and if the channel has been sensed to be idle during all the sensing slot durations of a defer duration

� immediately before this transmission. If the channel has not been sensed to be idle in a sensing slot duration �

� ��

when the eNB/gNB first senses the channel after it is ready to transmit or if the channel has been sensed to be not idle

during any of the sensing slot durations of a defer duration � immediately before this intended transmission, the

eNB/gNB proceeds to step 1 after sensing the channel to be idle during the sensing slot durations of a defer duration � .

The defer duration � consists of duration � =16�� immediately followed by � consecutive sensing slot durations

� � �
� , and � includes an idle sensing slot duration � at start of � .
�� � �� �
�� ≤�� ≤�� is the contention window. �� adjustment is described in clause 4.1.4.
���,� � ���,� �
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3GPP TS 37.213 version 17.6.0 Release 17 9 ETSI TS 137 213 V17.6.0 (2023-07)
�� and �� are chosen before step 1 of the procedure above.
���,� ���,�

� , �� , and �� are based on a channel access priority class � associated with the eNB/gNB transmission,

� ���,� ���,�
as shown in Table 4.1.1-1.

An eNB/gNB shall not transmit on a channel for a Channel Occupancy Time that exceeds � where the channel

����,�

access procedures are performed based on a channel access priority class � associated with the eNB/gNB transmissions,

as given in Table 4.1.1-1.

If an eNB/gNB transmits discovery burst(s) as described in clause 4.1.2 when � >0 in the procedure above, the

eNB/gNB shall not decrement � during the sensing slot duration(s) overlapping with discovery burst(s).

A gNB may use any channel access priority class for performing the procedures above to transmit transmission(s)

including discovery burst(s) satisfying the conditions described in this clause.

A gNB shall use a channel access priority class applicable to the unicast user plane data multiplexed in PDSCH for

performing the procedures above to transmit transmission(s) including unicast PDSCH with user plane data.

For � =3 and � =4 , if the absence of any other technology sharing the channel can be guaranteed on a long term

basis (e.g. by level of regulation), � =10��, otherwise, � =8��.
����,� ����,�
Table 4.1.1-1: Channel Access Priority Class (CAPC)
Channel
Access
� �� �� � allowed �� sizes
� ���,� ���,� ����,� �
Priority Class
(�)
1 1 3 7 2 ms {3,7}
2 1 7 15 3 ms {7,15}
3 3 15 63 8 or 10 ms {15,31,63}
4 7 15 1023 8 or 10 ms {15,31,63,127,255,511,1023}
4.1.1.1 Regional limitations on channel occupancy time

In Japan, if an eNB/gNB has transmitted a transmission after � =0 in step 4 of the procedure above, the eNB/gNB

may transmit the next continuous transmission, for duration of maximum � =4��, immediately after sensing the

channel to be idle for at least a sensing interval of � =34�� and if the total sensing and transmission time is not more

����
than 1000 ⋅� +� −1� ⋅� ��. The s
...