ETSI TS 138 321 V15.7.0 (2019-10)

5G; NR; Medium Access Control (MAC) protocol specification (3GPP TS 38.321 version 15.7.0 Release 15)

RTS/TSGR-0238321vf70

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
5G;
NR;
Medium Access Control (MAC) protocol specification
(3GPP TS 38.321 version 15.7.0 Release 15)

3GPP TS 38.321 version 15.7.0 Release 15 1 ETSI TS 138 321 V15.7.0 (2019-10)

Reference
RTS/TSGR-0238321vf70
Keywords
5G
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 38.321 version 15.7.0 Release 15 2 ETSI TS 138 321 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 38.321 version 15.7.0 Release 15 3 ETSI TS 138 321 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, symbols and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 8
4 General . 9
4.1 Introduction . 9
4.2 MAC architecture . 9
4.2.1 General . 9
4.2.2 MAC Entities . 9
4.3 Services . 10
4.3.1 Services provided to upper layers . 10
4.3.2 Services expected from physical layer . 11
4.4 Functions . 11
4.5 Channel structure . 11
4.5.1 General . 11
4.5.2 Transport Channels . 11
4.5.3 Logical Channels . 12
4.5.4 Mapping of Transport Channels to Logical Channels . 12
4.5.4.1 General . 12
4.5.4.2 Uplink mapping . 12
4.5.4.3 Downlink mapping . 12
5 MAC procedures . 13
5.1 Random Access procedure . 13
5.1.1 Random Access procedure initialization . 13
5.1.2 Random Access Resource selection . 16
5.1.3 Random Access Preamble transmission . 18
5.1.4 Random Access Response reception. 19
5.1.5 Contention Resolution . 21
5.1.6 Completion of the Random Access procedure . 22
5.2 Maintenance of Uplink Time Alignment . 22
5.3 DL-SCH data transfer . 24
5.3.1 DL Assignment reception . 24
5.3.2 HARQ operation . 25
5.3.2.1 HARQ Entity. 25
5.3.2.2 HARQ process . 25
5.3.3 Disassembly and demultiplexing . 26
5.4 UL-SCH data transfer . 27
5.4.1 UL Grant reception . 27
5.4.2 HARQ operation . 28
5.4.2.1 HARQ Entity. 28
5.4.2.2 HARQ process . 30
5.4.3 Multiplexing and assembly . 30
5.4.3.1 Logical Channel Prioritization . 30
5.4.3.1.1 General . 30
5.4.3.1.2 Selection of logical channels . 31
5.4.3.1.3 Allocation of resources . 31
5.4.3.2 Multiplexing of MAC Control Elements and MAC SDUs . 32
5.4.4 Scheduling Request. 32
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 4 ETSI TS 138 321 V15.7.0 (2019-10)
5.4.5 Buffer Status Reporting . 34
5.4.6 Power Headroom Reporting . 36
5.5 PCH reception . 38
5.6 BCH reception . 38
5.7 Discontinuous Reception (DRX) . 38
5.8 Transmission and reception without dynamic scheduling . 40
5.8.1 Downlink . 40
5.8.2 Uplink . 41
5.9 Activation/Deactivation of SCells . 42
5.10 Activation/Deactivation of PDCP duplication. 43
5.11 MAC reconfiguration . 44
5.12 MAC Reset . 44
5.13 Handling of unknown, unforeseen and erroneous protocol data . 44
5.14 Handling of measurement gaps . 45
5.15 Bandwidth Part (BWP) operation . 45
5.16 SUL operation . 47
5.17 Beam Failure Detection and Recovery procedure . 47
5.18 Handling of MAC CEs . 49
5.18.1 General . 49
5.18.2 Activation/Deactivation of Semi-persistent CSI-RS/CSI-IM resource set . 49
5.18.3 Aperiodic CSI Trigger State Subselection . 49
5.18.4 Activation/Deactivation of UE-specific PDSCH TCI state . 49
5.18.5 Indication of TCI state for UE-specific PDCCH . 50
5.18.6 Activation/Deactivation of Semi-persistent CSI reporting on PUCCH . 50
5.18.7 Activation/Deactivation of Semi-persistent SRS . 50
5.18.8 Activation/Deactivation of spatial relation of PUCCH resource . 50
5.18.9 Activation/Deactivation of semi-persistent ZP CSI-RS resource set . 50
5.18.10 Recommended Bit Rate . 51
5.19 Data inactivity monitoring . 51
6 Protocol Data Units, formats and parameters . 52
6.1 Protocol Data Units . 52
6.1.1 General . 52
6.1.2 MAC PDU (DL-SCH and UL-SCH except transparent MAC and Random Access Response) . 52
6.1.3 MAC Control Elements (CEs) . 53
6.1.3.1 Buffer Status Report MAC CEs . 53
6.1.3.2 C-RNTI MAC CE . 58
6.1.3.3 UE Contention Resolution Identity MAC CE . 58
6.1.3.4 Timing Advance Command MAC CE . 58
6.1.3.5 DRX Command MAC CE . 59
6.1.3.6 Long DRX Command MAC CE . 59
6.1.3.7 Configured Grant Confirmation MAC CE . 59
6.1.3.8 Single Entry PHR MAC CE . 59
6.1.3.9 Multiple Entry PHR MAC CE . 60
6.1.3.10 SCell Activation/Deactivation MAC CEs . 62
6.1.3.11 Duplication Activation/Deactivation MAC CE. 63
6.1.3.12 SP CSI-RS/CSI-IM Resource Set Activation/Deactivation MAC CE . 63
6.1.3.13 Aperiodic CSI Trigger State Subselection MAC CE . 64
6.1.3.14 TCI States Activation/Deactivation for UE-specific PDSCH MAC CE . 65
6.1.3.15 TCI State Indication for UE-specific PDCCH MAC CE . 65
6.1.3.16 SP CSI reporting on PUCCH Activation/Deactivation MAC CE . 66
6.1.3.17 SP SRS Activation/Deactivation MAC CE . 67
6.1.3.18 PUCCH spatial relation Activation/Deactivation MAC CE. 68
6.1.3.19 SP ZP CSI-RS Resource Set Activation/Deactivation MAC CE . 69
6.1.3.20 Recommended bit rate MAC CE . 69
6.1.4 MAC PDU (transparent MAC) . 70
6.1.5 MAC PDU (Random Access Response) . 70
6.2 Formats and parameters . 71
6.2.1 MAC subheader for DL-SCH and UL-SCH . 71
6.2.2 MAC subheader for Random Access Response. 72
6.2.3 MAC payload for Random Access Response . 73
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 5 ETSI TS 138 321 V15.7.0 (2019-10)
7 Variables and constants . 73
7.1 RNTI values . 73
7.2 Backoff Parameter values . 74
7.3 DELTA_PREAMBLE values . 75
7.4 PRACH Mask Index values. 76
Annex A (informative): Change history . 77
History . 79

ETSI
3GPP TS 38.321 version 15.7.0 Release 15 6 ETSI TS 138 321 V15.7.0 (2019-10)
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
3GPP TS 38.321 version 15.7.0 Release 15 7 ETSI TS 138 321 V15.7.0 (2019-10)
1 Scope
The present document specifies the NR 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 38.300: "NR; Overall description; Stage 2".
[3] 3GPP TS 38.322: "NR; Radio Link Control (RLC) protocol specification".
[4] 3GPP TS 38.323: "NR; Packet Data Convergence Protocol (PDCP) protocol specification".
[5] 3GPP TS 38.331: "NR; Radio Resource Control (RRC); Protocol specification".
[6] 3GPP TS 38.213: "NR; Physical Layer Procedures for control".
[7] 3GPP TS 38.214: "NR; Physical Layer Procedures for data".
[8] 3GPP TS 38.211: "NR; Physical channels and modulation".
[9] 3GPP TS 38.212: "NR; Multiplexing and channel coding".
[10] Void.
[11] 3GPP TS 38.133: "NR; Requirements for support of radio resource management".
[12] 3GPP TS 36.133: "Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for
support of radio resource management".
[13] 3GPP TS 26.114: "Technical Specification Group Services and System Aspects; IP Multimedia
Subsystem (IMS); Multimedia Telephony; Media handling and interaction".
[14] 3GPP TS 38.101-1: "NR; User Equipment (UE) radio transmission and reception; Part 1: Range 1
Standalone".
[15] 3GPP TS 38.101-2: "NR; User Equipment (UE) radio transmission and reception; Part 2: Range 2
Standalone".
[16] 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".
[17] 3GPP TS 36.213: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Layer
Procedures".
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 8 ETSI TS 138 321 V15.7.0 (2019-10)
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].
HARQ information: HARQ information for DL-SCH or for UL-SCH transmissions consists of New Data Indicator
(NDI), Transport Block size (TBS), Redundancy Version (RV), and HARQ process ID.
Msg3: Message transmitted on UL-SCH containing a C-RNTI MAC CE or CCCH SDU, submitted from upper layer
and associated with the UE Contention Resolution Identity, as part of a Random Access procedure.
PDCCH occasion: A time duration (i.e. one or a consecutive number of symbols) during which the MAC entity is
configured to monitor the PDCCH.
Serving Cell: A PCell, a PSCell, or an SCell in TS 38.331 [5].
Special Cell: For Dual Connectivity operation the term Special Cell refers to the PCell of the MCG or the PSCell of the
SCG depending on if the MAC entity is associated to the MCG or the SCG, respectively. Otherwise the term Special
Cell refers to the PCell. A Special Cell supports PUCCH transmission and contention-based Random Access, and is
always activated.
Timing Advance Group: A group of Serving Cells that is configured by RRC and that, for the cells with a UL
configured, using the same timing reference cell and the same Timing Advance value. A Timing Advance Group
containing the SpCell of a MAC entity is referred to as Primary Timing Advance Group (PTAG), whereas the term
Secondary Timing Advance Group (STAG) refers to other TAGs.
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. The duration of a timer is not updated until they are stopped or expires (e.g. due to
BWP switching).
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].
BSR Buffer Status Report
BWP Bandwidth Part
CE Control Element
CSI Channel State Information
CSI-IM CSI Intereference Measurement
CSI-RS CSI Reference Signal
CS-RNTI Configured Scheduling RNTI
INT-RNTI Interruption RNTI
LCG Logical Channel Group
LCP Logical Channel Prioritization
MCG Master Cell Group
NUL Normal Uplink
NZP CSI-RS Non-Zero Power CSI-RS
PHR Power Headroom Report
PTAG Primary Timing Advance Group
QCL Quasi-colocation
RS Reference Signal
SCG Secondary Cell Group
SFI-RNTI Slot Format Indication RNTI
SI System Information
SpCell Special Cell
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 9 ETSI TS 138 321 V15.7.0 (2019-10)
SP Semi-Persistent
SP-CSI-RNTI Semi-Persistent CSI RNTI
SPS Semi-Persistent Scheduling
SR Scheduling Request
SS Synchronization Signals
SSB Synchronization Signal Block
STAG Secondary Timing Advance Group
SUL Supplementary Uplink
TAG Timing Advance Group
TCI Transmission Configuration Indicator
TPC-SRS-RNTI Transmit Power Control-Sounding Reference Symbols-RNTI
ZP CSI-RS Zero Power CSI-RS
4 General
4.1 Introduction
The objective of this clause is to describe the MAC architecture and the MAC entity of the UE from a functional point
of view.
4.2 MAC architecture
4.2.1 General
This clause describes a model of the MAC i.e. it does not specify or restrict implementations.
RRC is in control of the MAC configuration.
4.2.2 MAC Entities
The MAC entity of the UE handles the following transport channels:
- Broadcast Channel (BCH);
- Downlink Shared Channel(s) (DL-SCH);
- Paging Channel (PCH);
- Uplink Shared Channel(s) (UL-SCH);
- Random Access Channel(s) (RACH).
When the UE is configured with SCG, two MAC entities are configured to the UE: one for the MCG and one for the
SCG.
The functions of the different MAC entities in the UE operate independently unless otherwise specified. The timers and
parameters used in each MAC entity are configured independently unless otherwise specified. The Serving Cells, C-
RNTI, radio bearers, logical channels, upper and lower layer entities, LCGs, and HARQ entities considered by each
MAC entity refer to those mapped to that MAC entity unless otherwise specified.
If the MAC entity is configured with one or more SCells, there are multiple DL-SCH and there may be multiple UL-
SCH as well as multiple RACH per MAC entity; one DL-SCH, one UL-SCH, and one RACH on the SpCell, one DL-
SCH, zero or one UL-SCH and zero or one RACH for each SCell.
If the MAC entity is not configured with any SCell, there is one DL-SCH, one UL-SCH, and one RACH per MAC
entity.
Figure 4.2.2-1 illustrates one possible structure of the MAC entity when SCG is not configured.
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 10 ETSI TS 138 321 V15.7.0 (2019-10)

Figure 4.2.2-1: MAC structure overview
Figure 4.2.2-2 illustrates one possible structure for the MAC entities when MCG and SCG are configured.

Figure 4.2.2-2: MAC structure overview with two MAC entities
4.3 Services
4.3.1 Services provided to upper layers
The MAC sublayer provides the following services to upper layers:
- data transfer;
- radio resource allocation.
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 11 ETSI TS 138 321 V15.7.0 (2019-10)
4.3.2 Services expected from physical layer
The MAC sublayer expects the following services from the physical layer:
- data transfer services;
- signalling of HARQ feedback;
- signalling of Scheduling Request;
- measurements (e.g. Channel Quality Indication (CQI)).
4.4 Functions
The MAC sublayer supports the following functions:
- mapping between logical channels and transport channels;
- multiplexing of MAC SDUs from one or different logical channels onto transport blocks (TB) to be delivered to
the physical layer on transport channels;
- demultiplexing of MAC SDUs to one or different logical channels from transport blocks (TB) delivered from the
physical layer on transport channels;
- scheduling information reporting;
- error correction through HARQ;
- logical channel prioritisation.
The relevance of MAC functions for uplink and downlink is indicated in Table 4.4-1.
Table 4.4-1: The link direction association of MAC functions.
MAC function Downlink Uplink
Mapping between logical channels and transport channels X X
Multiplexing X
Demultiplexing X
Scheduling information reporting X
Error correction through HARQ X X
Logical Channel prioritisation X

4.5 Channel structure
4.5.1 General
The MAC sublayer operates on the channels defined below; transport channels are SAPs between MAC and Layer 1,
logical channels are SAPs between MAC and RLC.
4.5.2 Transport Channels
The MAC sublayer uses the transport channels listed in Table 4.5.2-1 below.
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 12 ETSI TS 138 321 V15.7.0 (2019-10)
Table 4.5.2-1: Transport channels used by MAC
Transport channel name Acronym Downlink Uplink
Broadcast Channel BCH X
Downlink Shared Channel DL-SCH X
Paging Channel PCH X
Uplink Shared Channel UL-SCH X
Random Access Channel RACH X
4.5.3 Logical Channels
The MAC sublayer provides data transfer services on logical channels. To accommodate different kinds of data transfer
services, multiple types of logical channels are defined i.e. each supporting transfer of a particular type of information.
Each logical channel type is defined by what type of information is transferred.
The MAC sublayer provides the control and traffic channels listed in Table 4.5.3-1 below.
Table 4.5.3-1: Logical channels provided by MAC.
Logical channel name Acronym Control channel Traffic channel
Broadcast Control Channel BCCH X
Paging Control Channel PCCH X
Common Control Channel CCCH X
Dedicated Control Channel DCCH X
Dedicated Traffic Channel DTCH X

4.5.4 Mapping of Transport Channels to Logical Channels
4.5.4.1 General
Both for uplink and downlink, the MAC entity is responsible for mapping logical channels onto transport channels. This
mapping depends on the multiplexing that is configured by RRC.
4.5.4.2 Uplink mapping
The uplink logical channels can be mapped as described in Table 4.5.4.2-1.
Table 4.5.4.2-1: Uplink channel mapping.
Transport channel UL-SCH RACH
Logical channel
CCCH X
DCCH X
DTCH X
4.5.4.3 Downlink mapping
The downlink logical channels can be mapped as described in Table 4.5.4.3-1.
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 13 ETSI TS 138 321 V15.7.0 (2019-10)
Table 4.5.4.3-1: Downlink channel mapping.
Transport channel BCH PCH DL-SCH
Logical channel
BCCH X X
PCCH X
CCCH  X
DCCH  X
DTCH  X
5 MAC procedures
5.1 Random Access procedure
5.1.1 Random Access procedure initialization
The Random Access procedure described in this clause is initiated by a PDCCH order, by the MAC entity itself, or by
RRC for the events in accordance with TS 38.300 [2]. There is only one Random Access procedure ongoing at any
point in time in a MAC entity. The Random Access procedure on an SCell shall only be initiated by a PDCCH order
with ra-PreambleIndex different from 0b000000.
NOTE 1: If a new Random Access procedure is triggered while another is already ongoing in the MAC entity, it is
up to UE implementation whether to continue with the ongoing procedure or start with the new procedure
(e.g. for SI request).
RRC configures the following parameters for the Random Access procedure:
- prach-ConfigurationIndex: the available set of PRACH occasions for the transmission of the Random Access
Preamble;
- preambleReceivedTargetPower: initial Random Access Preamble power;
- rsrp-ThresholdSSB: an RSRP threshold for the selection of the SSB. If the Random Access procedure is initiated
for beam failure recovery, rsrp-ThresholdSSB used for the selection of the SSB within candidateBeamRSList
refers to rsrp-ThresholdSSB in BeamFailureRecoveryConfig IE;
- rsrp-ThresholdCSI-RS: an RSRP threshold for the selection of CSI-RS. If the Random Access procedure is
initiated for beam failure recovery, rsrp-ThresholdCSI-RS is equal to rsrp-ThresholdSSB in
BeamFailureRecoveryConfig IE;
- rsrp-ThresholdSSB-SUL: an RSRP threshold for the selection between the NUL carrier and the SUL carrier;
- candidateBeamRSList: a list of reference signals (CSI-RS and/or SSB) identifying the candidate beams for
recovery and the associated Random Access parameters;
- recoverySearchSpaceId: the search space identity for monitoring the response of the beam failure recovery
request;
- powerRampingStep: the power-ramping factor;
- powerRampingStepHighPriority: the power-ramping factor in case of prioritized Random Access procedure;
- scalingFactorBI: a scaling factor for prioritized Random Access procedure;
- ra-PreambleIndex: Random Access Preamble;
- ra-ssb-OccasionMaskIndex: defines PRACH occasion(s) associated with an SSB in which the MAC entity may
transmit a Random Access Preamble (see clause 7.4);
- ra-OccasionList: defines PRACH occasion(s) associated with a CSI-RS in which the MAC entity may transmit a
Random Access Preamble;
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 14 ETSI TS 138 321 V15.7.0 (2019-10)
- ra-PreambleStartIndex: the starting index of Random Access Preamble(s) for on-demand SI request;
- preambleTransMax: the maximum number of Random Access Preamble transmission;
- ssb-perRACH-OccasionAndCB-PreamblesPerSSB: defines the number of SSBs mapped to each PRACH
occasion and the number of contention-based Random Access Preambles mapped to each SSB;
- if groupBconfigured is configured, then Random Access Preambles group B is configured.
- Amongst the contention-based Random Access Preambles associated with an SSB (as defined in TS 38.213
[6]), the first numberOfRA-PreamblesGroupA Random Access Preambles belong to Random Access
Preambles group A. The remaining Random Access Preambles associated with the SSB belong to Random
Access Preambles group B (if configured).
NOTE 2: If Random Access Preambles group B is supported by the cell Random Access Preambles group B is
included for each SSB.
- if Random Access Preambles group B is configured:
- ra-Msg3SizeGroupA: the threshold to determine the groups of Random Access Preambles;
- msg3-DeltaPreamble: ∆ in TS 38.213 [6];
PREAMBLE_Msg3
- messagePowerOffsetGroupB: the power offset for preamble selection;
- numberOfRA-PreamblesGroupA: defines the number of Random Access Preambles in Random Access
Preamble group A for each SSB.
- the set of Random Access Preambles and/or PRACH occasions for SI request, if any;
- the set of Random Access Preambles and/or PRACH occasions for beam failure recovery request, if any;
- the set of Random Access Preambles and/or PRACH occasions for reconfiguration with sync, if any;
- ra-ResponseWindow: the time window to monitor RA response(s) (SpCell only);
- ra-ContentionResolutionTimer: the Contention Resolution Timer (SpCell only).
In addition, the following information for related Serving Cell is assumed to be available for UEs:
- if Random Access Preambles group B is configured:
- if the Serving Cell for the Random Access procedure is configured with supplementary uplink as specified in
TS 38.331 [5], and SUL carrier is selected for performing Random Access Procedure:
- P of the SUL carrier as specified in TS 38.101-1 [14], TS 38.101-2 [15], and TS 38.101-3 [16].
CMAX,f,c
- else:
- PCMAX,f,c of the NUL carrier as specified in TS 38.101-1 [14], TS 38.101-2 [15], and TS 38.101-3 [16].
The following UE variables are used for the Random Access procedure:
- PREAMBLE_INDEX;
- PREAMBLE_TRANSMISSION_COUNTER;
- PREAMBLE_POWER_RAMPING_COUNTER;
- PREAMBLE_POWER_RAMPING_STEP;
- PREAMBLE_RECEIVED_TARGET_POWER;
- PREAMBLE_BACKOFF;
- PCMAX;
- SCALING_FACTOR_BI;
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 15 ETSI TS 138 321 V15.7.0 (2019-10)
- TEMPORARY_C-RNTI.
When the Random Access procedure is initiated on a Serving Cell, the MAC entity shall:
1> flush the Msg3 buffer;
1> set the PREAMBLE_TRANSMISSION_COUNTER to 1;
1> set the PREAMBLE_POWER_RAMPING_COUNTER to 1;
1> set the PREAMBLE_BACKOFF to 0 ms;
1> if the carrier to use for the Random Access procedure is explicitly signalled:
2> select the signalled carrier for performing Random Access procedure;
2> set the PCMAX to P of the signalled carrier.
CMAX,f,c
1> else if the carrier to use for the Random Access procedure is not explicitly signalled; and
1> if the Serving Cell for the Random Access procedure is configured with supplementary uplink as specified in TS
38.331 [5]; and
1> if the RSRP of the downlink pathloss reference is less than rsrp-ThresholdSSB-SUL:
2> select the SUL carrier for performing Random Access procedure;
2> set the PCMAX to P of the SUL carrier.
CMAX,f,c
1> else:
2> select the NUL carrier for performing Random Access procedure;
2> set the PCMAX to P of the NUL carrier.
CMAX,f,c
1> perform the BWP operation as specified in clause 5.15;
1> set PREAMBLE_POWER_RAMPING_STEP to powerRampingStep;
1> set SCALING_FACTOR_BI to 1;
1> if the Random Access procedure was initiated for beam failure recovery (as specified in clause 5.17); and
1> if beamFailureRecoveryConfig is configured for the active UL BWP of the selected carrier:
2> start the beamFailureRecoveryTimer, if configured;
2> apply the parameters powerRampingStep, preambleReceivedTargetPower, and preambleTransMax
configured in the beamFailureRecoveryConfig;
2> if powerRampingStepHighPriority is configured in the beamFailureRecoveryConfig:
3> set PREAMBLE_POWER_RAMPING_STEP to the powerRampingStepHighPriority.
2> else:
3> set PREAMBLE_POWER_RAMPING_STEP to powerRampingStep.
2> if scalingFactorBI is configured in the beamFailureRecoveryConfig:
3> set SCALING_FACTOR_BI to the scalingFactorBI.
1> else if the Random Access procedure was initiated for handover; and
1> if rach-ConfigDedicated is configured for the selected carrier:
2> if powerRampingStepHighPriority is configured in the rach-ConfigDedicated:
3> set PREAMBLE_POWER_RAMPING_STEP to the powerRampingStepHighPriority.
ETSI
3GPP TS 38.321 version 15.7.0 Release 15 16 ETSI TS 138 321 V15.7.0 (2019-10)
2> if scalingFactorBI is configured in the rach-ConfigDedicated:
3> set SCALING_FACTOR_BI to the scalingFactorBI.
1> perform the Random Access Resource selection procedure (see clause 5.1.2).
5.1.2 Random Access Resource selection
The MAC entity shall:
1> if the Random Access procedure was initiated for beam failure recovery (as specified in clause 5.17); and
1> if the beamFailureRecoveryTimer (in clause 5.17) is either running or not configured; and
1> if the contention-free Random Access Resources for beam failure recovery request associated with any of the
SSBs and/or CSI-RSs have been explicitly provided by RRC; and
1> if at least one of the SSBs with SS-RSRP above rsrp-ThresholdSSB amongst the SSBs in candidateBeamRSList
or the CSI-RSs with CSI-RSRP above rsrp-ThresholdCSI-RS amongst the CSI-RSs in candidateBeamRSList is
available:
2> select an SSB with SS-RSRP above rsrp-ThresholdSSB amongst the SSBs in candidateBeamRSList or a CSI-
RS with CSI-RSRP above rsrp-ThresholdCSI
...