ETSI TS 136 321 V15.7.0 (2019-10)

LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification (3GPP TS 36.321 version 15.7.0 Release 15)

RTS/TSGR-0236321vf70

General Information

• Status: Published
• Publication Date: 14-Oct-2019
• Technical Committee: 3GPP RAN 2 - Radio layer 2 specification and Radio layer 3 RR specification
• Current Stage: 12 - Completion
• Completion Date: 15-Oct-2019

Standards Content (Sample)

TECHNICAL SPECIFICATION
LTE;
Evolved Universal Terrestrial Radio Access (E-UTRA);
Medium Access Control (MAC) protocol specification
(3GPP TS 36.321 version 15.7.0 Release 15)

3GPP TS 36.321 version 15.7.0 Release 15 1 ETSI TS 136 321 V15.7.0 (2019-10)

Reference
RTS/TSGR-0236321vf70
Keywords
LTE
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: [phone]  Fax: [phone]

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

Important notice
The present document can be downloaded from:
http://www.etsi.org/standards-search
The present document may be made available in electronic versions and/or in print. The content of any electronic and/or
print versions of the present document shall not be modified without the prior written authorization of ETSI. In case of any
existing or perceived difference in contents between such versions and/or in print, the prevailing version of an ETSI
deliverable is the one made publicly available in PDF format at www.etsi.org/deliver.
Users of the present document should be aware that the document may be subject to revision or change of status.
Information on the current status of this and other ETSI documents is available at
https://portal.etsi.org/TB/ETSIDeliverableStatus.aspx
If you find errors in the present document, please send your comment to one of the following services:
https://portal.etsi.org/People/CommiteeSupportStaff.aspx
Copyright Notification
No part may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying
and microfilm except as authorized by written permission of ETSI.
The content of the PDF version shall not be modified without the written authorization of ETSI.
The copyright and the foregoing restriction extend to reproduction in all media.

© ETSI 2019.
All rights reserved.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its Members.

3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and
of the oneM2M Partners. ®
GSM and the GSM logo are trademarks registered and owned by the GSM Association.
ETSI
3GPP TS 36.321 version 15.7.0 Release 15 2 ETSI TS 136 321 V15.7.0 (2019-10)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Legal Notice
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities. These shall be
interpreted as being references to the corresponding ETSI deliverables.
The cross reference between 3GPP and ETSI identities can be found under http://webapp.etsi.org/key/queryform.asp.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
3GPP TS 36.321 version 15.7.0 Release 15 3 ETSI TS 136 321 V15.7.0 (2019-10)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 6
1 Scope . 7
2 References . 7
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 11
4 General . 12
4.1 Introduction . 12
4.2 MAC architecture . 12
4.2.1 MAC Entities . 12
4.3 Services . 15
4.3.1 Services provided to upper layers . 15
4.3.2 Services expected from physical layer . 15
4.4 Functions . 15
4.5 Channel structure . 16
4.5.1 Transport Channels . 16
4.5.2 Logical Channels . 16
4.5.3 Mapping of Transport Channels to Logical Channels . 17
4.5.3.1 Uplink mapping . 17
4.5.3.2 Downlink mapping . 17
4.5.3.3 Sidelink mapping . 18
5 MAC procedures . 19
5.1 Random Access procedure . 19
5.1.1 Random Access Procedure initialization . 19
5.1.2 Random Access Resource selection . 22
5.1.3 Random Access Preamble transmission . 24
5.1.4 Random Access Response reception. 25
5.1.5 Contention Resolution . 28
5.1.6 Completion of the Random Access procedure . 30
5.2 Maintenance of Uplink Time Alignment . 31
5.3 DL-SCH data transfer . 32
5.3.1 DL Assignment reception . 32
5.3.2 HARQ operation . 34
5.3.2.1 HARQ Entity. 34
5.3.2.2 HARQ process . 35
5.3.3 Disassembly and demultiplexing . 36
5.4 UL-SCH data transfer . 36
5.4.1 UL Grant reception . 36
5.4.2 HARQ operation . 40
5.4.2.1 HARQ entity . 40
5.4.2.2 HARQ process . 43
5.4.3 Multiplexing and assembly . 45
5.4.3.1 Logical channel prioritization . 45
5.4.3.2 Multiplexing of MAC Control Elements and MAC SDUs . 47
5.4.4 Scheduling Request. 47
5.4.5 Buffer Status Reporting . 49
5.4.5a Data Volume and Power Headroom Reporting . 51
5.4.6 Power Headroom Reporting . 51
5.5 PCH reception . 53
5.6 BCH reception . 53
ETSI
3GPP TS 36.321 version 15.7.0 Release 15 4 ETSI TS 136 321 V15.7.0 (2019-10)
5.7 Discontinuous Reception (DRX) . 54
5.7a Discontinuous Reception (DRX) for SC-PTM . 57
5.8 MAC reconfiguration . 58
5.9 MAC Reset . 58
5.10 Semi-Persistent Scheduling . 59
5.10.1 Downlink . 59
5.10.2 Uplink . 60
5.11 Handling of unknown, unforeseen and erroneous protocol data . 61
5.12 MCH reception . 61
5.13 Activation/Deactivation of SCells . 61
5.14 SL-SCH Data transfer . 63
5.14.1 SL-SCH Data transmission . 63
5.14.1.1 SL Grant reception and SCI transmission . 63
5.14.1.2 Sidelink HARQ operation . 69
5.14.1.2.1 Sidelink HARQ Entity . 69
5.14.1.2.2 Sidelink process . 69
5.14.1.3 Multiplexing and assembly . 70
5.14.1.3.1 Logical channel prioritization . 70
5.14.1.3.2 Multiplexing of MAC SDUs . 71
5.14.1.4 Buffer Status Reporting . 71
5.14.1.5 TX carrier (re-)selection for V2X sidelink communication . 73
5.14.2 SL-SCH Data reception . 74
5.14.2.1 SCI reception. 74
5.14.2.2 Sidelink HARQ operation . 74
5.14.2.2.1 Sidelink HARQ Entity . 74
5.14.2.2.2 Sidelink process . 75
5.14.2.3 Disassembly and demultiplexing . 76
5.15 SL-DCH data transfer . 76
5.15.1 SL-DCH data transmission . 76
5.15.1.1 Resource allocation . 76
5.15.1.2 Sidelink HARQ operation . 76
5.15.1.2.1 Sidelink HARQ Entity . 76
5.15.1.2.2 Sidelink process . 77
5.15.2 SL-DCH data reception . 77
5.15.2.1 Sidelink HARQ operation . 77
5.15.2.1.1 Sidelink HARQ Entity . 77
5.15.2.1.2 Sidelink process . 78
5.16 SL-BCH data transfer . 78
5.16.1 SL-BCH data transmission . 78
5.16.2 SL-BCH data reception . 79
5.17 Data inactivity monitoring . 79
5.18 Recommended Bit Rate . 79
5.19 Activation/Deactivation of CSI-RS resources . 80
5.20 Preallocated uplink grant . 80
5.21 SC-PTM Stop Indication . 80
5.22 Entering Dormant SCell state . 80
5.23 Autonomous Uplink . 82
5.24 Activation/Deactivation of PDCP duplication. 82
6 Protocol Data Units, formats and parameters . 83
6.1 Protocol Data Units . 83
6.1.1 General . 83
6.1.2 MAC PDU (DL-SCH and UL-SCH except transparent MAC and Random Access Response, MCH) . 83
6.1.3 MAC Control Elements . 85
6.1.3.1 Buffer Status Report MAC Control Elements . 85
6.1.3.1a Sidelink BSR MAC Control Elements . 87
6.1.3.2 C-RNTI MAC Control Element . 88
6.1.3.3 DRX Command MAC Control Element . 89
6.1.3.4 UE Contention Resolution Identity MAC Control Element . 89
6.1.3.5 Timing Advance Command MAC Control Element . 89
6.1.3.6 Power Headroom Report MAC Control Element . 90
6.1.3.6a Extended Power Headroom Report MAC Control Elements . 90
ETSI
3GPP TS 36.321 version 15.7.0 Release 15 5 ETSI TS 136 321 V15.7.0 (2019-10)
6.1.3.6b Dual Connectivity Power Headroom Report MAC Control Element . 93
6.1.3.7 MCH Scheduling Information MAC Control Element . 95
6.1.3.7a Extended MCH Scheduling Information MAC Control Element . 96
6.1.3.8 Activation/Deactivation MAC Control Elements . 97
6.1.3.9 Long DRX Command MAC Control Element . 98
6.1.3.10 Data Volume and Power Headroom Report MAC Control Element . 98
6.1.3.11 SPS confirmation MAC Control Element . 99
6.1.3.12 SC-PTM Stop Indication MAC Control Element . 99
6.1.3.13 Recommended bit rate MAC Control Element . 100
6.1.3.14 Activation/Deactivation of CSI-RS resources MAC Control Element . 101
6.1.3.15 Hibernation MAC Control Elements . 102
6.1.3.16 AUL confirmation MAC Control Element . 103
6.1.3.17 PDCP Duplication Activation/Deactivation MAC Control Element . 104
6.1.4 MAC PDU (transparent MAC) . 104
6.1.5 MAC PDU (Random Access Response) . 104
6.1.6 MAC PDU (SL-SCH) . 106
6.2 Formats and parameters . 108
6.2.1 MAC header for DL-SCH, UL-SCH and MCH. 108
6.2.2 MAC header for Random Access Response . 111
6.2.3 MAC payload for Random Access Response . 111
6.2.4 MAC header for SL-SCH . 111
7 Variables and constants . 112
7.1 RNTI values . 112
7.2 Backoff Parameter values . 114
7.3 PRACH Mask Index values. 116
7.4 Subframe_Offset values . 116
7.5 TTI_BUNDLE_SIZE value. 116
7.6 DELTA_PREAMBLE values . 116
7.7 HARQ RTT Timers . 117
7.8 DL_REPETITION_NUMBER value . 119
7.9 UL_REPETITION_NUMBER value . 119
Annex A (normative): Handling of measurement gaps . 120
Annex B (normative): Contention resolution for RACH access . 121
Annex C (informative): Intended UE behaviour for DRX Timers . 124
Annex D (normative): List of CRs Containing Early Implementable Features and
Corrections . 126
Annex E (informative): Change history . 127
History . 135

ETSI
3GPP TS 36.321 version 15.7.0 Release 15 6 ETSI TS 136 321 V15.7.0 (2019-10)
Foreword
rd
This Technical Specification has been produced by the 3 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
3GPP TS 36.321 version 15.7.0 Release 15 7 ETSI TS 136 321 V15.7.0 (2019-10)
1 Scope
The present document specifies the E-UTRA MAC protocol.
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 36.213: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Layer
Procedures".
[3] 3GPP TS 36.322: "Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Link Control
(RLC) protocol specification".
[4] 3GPP TS 36.323: "Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data
Convergence Protocol (PDCP) Specification".
[5] 3GPP TS 36.212: "Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and
channel coding".
[6] 3GPP TS 36.214: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer;
Measurements".
[7] 3GPP TS 36.211: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and
Modulation".
[8] 3GPP TS 36.331: "Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource
Control (RRC); Protocol specification".
[9] 3GPP TS 36.133: "Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for
support of radio resource management".
[10] 3GPP TS 36.101: "Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE)
radio transmission and reception".
[11] 3GPP TS 36.216: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer for
relaying operation".
[12] 3GPP TS 36.306: "Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE)
radio access capabilities".
[13] 3GPP TS 23.303: "Proximity-based services (ProSe); Stage 2".
[14] 3GPP TS 23.285: "Architecture enhancements for V2X services".
[15] 3GPP TS 24.386: "User Equipment (UE) to V2X control function; protocol aspects; Stage 3".
[16] 3GPP TS 26.114: "IP Multimedia Subsystem (IMS); Multimedia telephony; Media handling and
interaction".
[17] 3GPP TS 38.323: "NR; Packet Data Convergence Protocol (PDCP) specification".
ETSI
3GPP TS 36.321 version 15.7.0 Release 15 8 ETSI TS 136 321 V15.7.0 (2019-10)
[18] 3GPP TS 38.213: "NR; Physical Layer Procedures for control".
[19] 3GPP TS 38.133: "NR; Requirements for support of radio resource management".
[20] 3GPP TS 36.300: "Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal
Terrestrial Radio Access (E-UTRAN); Overall description; Stage 2".
[21] 3GPP TS 38.101-3: "NR; User Equipment (UE) radio transmission and reception; Part 3: Range 1
and Range 2 Interworking operation with other radios".
3 Definitions 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].
Active Time: Time related to DRX operation, as defined in clause 5.7, during which the MAC entity monitors the
PDCCH.
mac-ContentionResolutionTimer: Specifies the number of consecutive subframe(s) during which the MAC entity shall
monitor the PDCCH after Msg3 is transmitted.
DRX Cycle: Specifies the periodic repetition of the On Duration followed by a possible period of inactivity (see figure
3.1-1 below).
Figure 3.1-1: DRX Cycle
drx-InactivityTimer: Except for NB-IoT UEs, BL UEs or UEs in enhanced coverage, it specifies the number of
consecutive PDCCH-subframe(s) after the subframe in which a PDCCH indicates an initial UL, DL or SL user data
transmission for this MAC entity. For NB-IoT UEs, it specifies the number of consecutive PDCCH-subframe(s) after
the subframe in which the HARQ RTT timer or UL HARQ RTT timer expires. For BL UEs or UEs in enhanced
coverage, it specifies the number of consecutive PDCCH-subframe(s) following the subframe containing the last
repetition of the PDCCH reception that indicates an initial UL or DL user data transmission for this MAC entity.
drx-RetransmissionTimer: Specifies the maximum number of consecutive PDCCH-subframe(s) until a DL
retransmission is received.
drx-RetransmissionTimerShortTTI: Specifies the maximum number of consecutive TTI(s) until a DL retransmission is
received for HARQ processes scheduled using short TTI.
drxShortCycleTimer: Specifies the number of consecutive subframe(s) the MAC entity shall follow the Short DRX
cycle.
drxStartOffset: Specifies the subframe where the DRX Cycle starts.
drx-ULRetransmissionTimer: Specifies the maximum number of consecutive PDCCH-subframe(s) until a grant for UL
retransmission or the HARQ feedback is received.
drx-ULRetransmissionTimeShortTTI: Specifies the maximum number of consecutive TTI(s) until a grant for UL
retransmission is received for HARQ processes scheduled using short TTI.
ETSI
3GPP TS 36.321 version 15.7.0 Release 15 9 ETSI TS 136 321 V15.7.0 (2019-10)
Early Data Transmission: Allows one uplink data transmission optionally followed by one downlink data transmission
during the random access procedure as specified in TS 36.300 [20]. The S1 connection is established or resumed upon
reception of the uplink data and may be released or suspended along with the transmission of the downlink data. Early
data transmission refers to both CP-EDT and UP-EDT.
HARQ information: HARQ information for DL-SCH or for UL-SCH transmissions consists of New Data Indicator
(NDI), Transport Block (TB) size. For DL-SCH transmissions and for asynchronous UL HARQ and for autonomous
UL HARQ, the HARQ information also includes HARQ process ID, except for UEs in NB-IoT configured with a single
HARQ process for which this information is not present. For UL-SCH transmission the HARQ information also
includes Redundancy Version (RV). In case of spatial multiplexing on DL-SCH the HARQ information comprises a set
of NDI and TB size for each transport block. HARQ information for SL-SCH and SL-DCH transmissions consists of
TB size only.
HARQ RTT Timer: This parameter specifies the minimum amount of subframe(s) before a DL assignment for HARQ
retransmission is expected by the MAC entity.
Msg3: Message transmitted on UL-SCH containing a C-RNTI MAC CE or a CCCH SDU optionally multiplexed with
DTCH for the UP-EDT, submitted from upper layer and associated with the UE Contention Resolution Identity, as part
of a random access procedure.
NB-IoT: NB-IoT allows access to network services via E-UTRA with a channel bandwidth limited to 200 kHz.
NB-IoT UE: A UE that uses NB-IoT.
onDurationTimer: Specifies the number of consecutive PDCCH-subframe(s) at the beginning of a DRX Cycle.
PDCCH: Refers to the PDCCH (see TS 36.211 [7]), EPDCCH (in subframes when configured), MPDCCH (see
TS 36.213 [2]), for an RN with R-PDCCH configured and not suspended, to the R-PDCCH, for NB-IoT to the
NPDCCH or for short TTI to SPDCCH.
PDCCH period (pp): Refers to the interval between the start of two consecutive PDCCH occasions and depends on the
currently used PDCCH search space, as specified in TS 36.213 [2]. A PDCCH occasion is the start of a search space
and is defined by subframe k0 as specified in clause 16.6 of TS 36.213 [2]. The calculation of number of PDCCH-
subframes for the timer configured in units of a PDCCH period is done by multiplying the number of PDCCH periods
with npdcch-NumRepetitions-RA when the UE uses the common search space or by npdcch-NumRepetitions when the
UE uses the UE specific search space. When counting a timer whose length is calculated in PDCCH-subframes, the UE
shall include PDCCH-subframes that will be dropped or not required to be monitored as specified in clause 16.6 of
TS 36.213 [2]. The calculation of number of subframes for the timer configured in units of a PDCCH period is done by
multiplying the number of PDCCH periods with duration between two consecutive PDCCH occasions.
PDCCH-subframe: Refers to a subframe with PDCCH. This represents the union over PDCCH-subframes for all
serving cells excluding cells configured with cross carrier scheduling for both uplink and downlink, as specified in
TS 36.331 [8]; except if the UE is not capable of simultaneous reception and transmission in the aggregated cells where
this instead represents the PDCCH-subframes of the SpCell.
- For FDD serving cells, all subframes represent PDCCH-subframes, unless specified otherwise in this clause.
- For TDD serving cells, all downlink subframes and subframes including DwPTS of the TDD UL/DL
configuration indicated by tdd-Config, as specified in TS 36.331 [8] of the cell represent PDCCH-subframes,
unless specified otherwise in this clause.
- For serving cells operating according to Frame structure Type 3, all subframes represent PDCCH-subframes.
- For RNs with an RN subframe configuration configured and not suspended, in its communication with the E-
UTRAN, all downlink subframes configured for RN communication with the E-UTRAN represent PDCCH-
subframes.
- For SC-PTM reception on an FDD cell, all subframes except MBSFN subframes represent PDCCH-subframes,
unless specified otherwise in this clause.
- For SC-PTM reception on a TDD cell, all downlink subframes and subframes including DwPTS of the TDD
UL/DL configuration indicated by tdd-Config, as specified in TS 36.331 [8] of the cell except MBSFN
subframes represent PDCCH-subframes, unless specified otherwise in this clause.
ETSI
3GPP TS 36.321 version 15.7.0 Release 15 10 ETSI TS 136 321 V15.7.0 (2019-10)
- For BL UE or UE in enhanced coverage, all subframes in which the UE is required to monitor MPDCCH
represent PDCCH-subframes among all valid subframes regardless of whether the subframe is dropped, see
clause 9.1.5 of TS 36.213 [2].
- For NB-IoT UE, all subframes that are part of the NPDCCH search space represent PDCCH-subframes among
all NB-IoT downlink subframes, including those which the UE is not required to monitor as specified in clause
16.6 of TS 36.213 [2].
PDSCH: Refers to subframe-PDSCH/slot-PDSCH/subslot-PDSCH or for NB-IoT to NPDSCH.
PRACH: Refers to PRACH or for NB-IoT to NPRACH.
PRACH Resource Index: The index of a PRACH within a system frame, see TS 36.211 [7]
Primary Timing Advance Group: Timing Advance Group containing the SpCell.
PUCCH SCell: An SCell configured with PUCCH/SPUCCH.
PUSCH: Refers to subframe-PUSCH/slot-PUSCH/subslot-PUSCH or for NB-IoT to NPUSCH.
ra-PRACH-MaskIndex: Defines in which PRACHs within a system frame the MAC entity can transmit a Random
Access Preamble (see clause 7.3).
RA-RNTI: The Random Access RNTI is used on the PDCCH when Random Access Response messages are
transmitted. It unambiguously identifies which time-frequency resource was utilized by the MAC entity to transmit the
Random Access preamble.
SC Period: Sidelink Control period, the time period consisting of transmission of SCI and its corresponding data.
SCI: The Sidelink Control Information contains the sidelink scheduling information such as resource block assignment,
modulation and coding scheme, Group Destination ID (for sidelink communication) and PPPP (for V2X sidelink
communication), see TS 36.212 [5].
Secondary Timing Advance Group: Timing Advance Group not containing the SpCell. A Secondary Timing Advance
Group contains at least one Serving Cell with an UL configured.
Serving Cell: A Primary or a Secondary Cell, see TS 36.331 [8].
Short Processing Time: For 1 ms TTI length, the operation with short processing time in UL data transmission and DL
data reception.
Short TTI: TTI length based on a slot or a subslot.
Sidelink: UE to UE interface for sidelink communication, sidelink discovery and V2X sidelink communication. The
sidelink corresponds to the PC5 interface as defined in TS 23.303 [13] for sidelink communication and sidelink
discovery, and as defined in TS 23.285 [14] for V2X sidelink communication.
Sidelink communication: AS functionality enabling ProSe Direct Communication as defined in TS 23.303 [13],
between two or more nearby UEs, using E-UTRA technology but not traversing any network node.
Sidelink Discovery Gap for Reception: Time period during which the UE does not receive any channels in DL from
any serving cell, except during random access procedure.
Sidelink Discovery Gap for Transmission: Time period during which the UE prioritizes transmission of sidelink
discovery and associated procedures e.g. re-tuning and synchronisation over transmission of channels in UL, if they
occur in the same subframe, except during random access procedure.
Special Cell: For Dual Connectivity operation the term Special Cell refers to the PCell of the MCG or the PSCell of the
SCG, otherwise the term Special Cell refers to the PCell.
Timing Advance Group: A group of Serving Cells that is configured by RRC and that, for the cells with an UL
configured, using the same timing reference cell and the same Timing Advance value.
UL HARQ RTT Timer: This parameter specifies the minimum amount of subframe(s) before a UL HARQ
retransmission grant is expected by the MAC entity.
ETSI
3GPP TS 36.321 version 15.7.0 Release 15 11 ETSI TS 136 321 V15.7.0 (2019-10)
V2X sidelink communication: AS functionality enabling V2X Communication as defined in TS 23.285 [14], between
nearby UEs, using E-UTRA technology but not traversing any network node.
NOTE: A timer is running once it is started, until it is stopped or until it expires; otherwise it is not running. A
timer can be started if it is not running or restarted if it is running. A Timer is always started or restarted
from its initial value.
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].
AUL Autonomous Uplink
BL Bandwidth reduced Low complexity
BR Bandwidth Reduced
BSR Buffer Status Report
C-RNTI Cell RNTI
CBR Channel Busy Ratio
CC-RNTI Common Control RNTI
CQI Channel Quality Indicator
CRI CSI-RS Resource Indicator
CSI Channel State Information
DRB Data Radio Bearer
EDT Early Data Transmission
eIMTA Enhanced Interference Management and Traffic Adaptation
eIMTA-RNTI Enhanced Interference Management and Traffic Adaptation - RNTI
E-UTRA Evolved UMTS Terrestrial Radio Access
E-UTRAN Evolved UMTS Terrestrial Radio Access Network
G-RNTI Group RNTI
H-SFN Hyper SFN
MAC Medium Access Control
MCG Master Cell Group
M-RNTI MBMS RNTI
MPDCCH MTC Physical Downlink Control Channel
LCG Logical Channel Group
NB-IoT Narrow Band Internet of Things
NPDCCH Narrowband Physical Downlink Control Channel
NPDSCH Narrowband Physical Downlink Shared channel
NP
...