3GPP TS V ( )

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1 TS V ( ) Technical Specification 3rd Generation Partnership Project; Technical Specification Group adio Access Network; Evolved Universal Terrestrial adio Access (E-UTA); Medium Access Control (MAC) protocol specification (elease 13) The present document has been developed within the 3 rd Generation Partnership Project ( TM ) and may be further elaborated for the purposes of. The present document has not been subject to any approval process by the Organizational Partners and shall not be implemented. This Specification is provided for future development work within only. The Organizational Partners accept no liability for any use of this Specification. Specifications and reports for implementation of the TM system should be obtained via the Organizational Partners' Publications Offices.

2 2 TS V ( ) Keywords UMTS, radio Postal address support office address 650 oute des Lucioles - Sophia Antipolis Valbonne - FANCE Tel.: Fax: Internet Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. 2016, Organizational Partners (AIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). All rights reserved. UMTS is a Trade Mark of ETSI registered for the benefit of its members is a Trade Mark of ETSI registered for the benefit of its Members and of the Organizational Partners LTE is a Trade Mark of ETSI currently being registered for the benefit of its Members and of the Organizational Partners GSM and the GSM logo are registered and owned by the GSM Association

3 3 TS V ( ) Contents Foreword Scope eferences Definitions and abbreviations Definitions Abbreviations General Introduction MAC architecture MAC Entities Services Services provided to upper layers Services expected from physical layer Functions Channel structure Transport Channels Logical Channels Mapping of Transport Channels to Logical Channels Uplink mapping Downlink mapping Sidelink mapping MAC procedures andom Access procedure andom Access Procedure initialization andom Access esource selection andom Access Preamble transmission andom Access esponse reception Contention esolution Completion of the andom Access procedure Maintenance of Uplink Time Alignment DL-SCH data transfer DL Assignment reception HAQ operation HAQ Entity HAQ process Disassembly and demultiplexing UL-SCH data transfer UL Grant reception HAQ operation HAQ entity HAQ process Multiplexing and assembly Logical channel prioritization Multiplexing of MAC Control Elements and MAC SDUs Scheduling equest Buffer Status eporting a Data Volume and Power Headroom eporting Power Headroom eporting PCH reception BCH reception Discontinuous eception (DX) a Discontinuous eception (DX) for SC-PTM MAC reconfiguration MAC eset... 46

4 4 TS V ( ) 5.10 Semi-Persistent Scheduling Downlink Uplink Handling of unknown, unforeseen and erroneous protocol data MCH reception Activation/Deactivation of SCells SL-SCH Data transfer SL-SCH Data transmission SL Grant reception and SCI transmission Sidelink HAQ operation Sidelink HAQ Entity Sidelink process Multiplexing and assembly Logical channel prioritization Multiplexing of MAC SDUs Buffer Status eporting SL-SCH Data reception SCI reception Sidelink HAQ operation Sidelink HAQ Entity Sidelink process Disassembly and demultiplexing SL-DCH data transfer SL-DCH data transmission esource allocation Sidelink HAQ operation Sidelink HAQ Entity Sidelink process SL-DCH data reception Sidelink HAQ operation Sidelink HAQ Entity Sidelink process SL-BCH data transfer SL-BCH data transmission SL-BCH data reception Protocol Data Units, formats and parameters Protocol Data Units General MAC PDU (DL-SCH and UL-SCH except transparent MAC and andom Access esponse, MCH) MAC Control Elements Buffer Status eport MAC Control Elements a Sidelink BS MAC Control Elements C-NTI MAC Control Element DX Command MAC Control Element UE Contention esolution Identity MAC Control Element Timing Advance Command MAC Control Element Power Headroom eport MAC Control Element a Extended Power Headroom eport MAC Control Elements b Dual Connectivity Power Headroom eport MAC Control Element MCH Scheduling Information MAC Control Element a Extended MCH Scheduling Information MAC Control Element Activation/Deactivation MAC Control Elements Long DX Command MAC Control Element Data Volume and Power Headroom eport MAC Control Element MAC PDU (transparent MAC) MAC PDU (andom Access esponse) MAC PDU (SL-SCH) Formats and parameters MAC header for DL-SCH, UL-SCH and MCH MAC header for andom Access esponse MAC payload for andom Access esponse... 79

5 5 TS V ( ) MAC header for SL-SCH Variables and constants NTI values Backoff Parameter values PACH Mask Index values Subframe_Offset values TTI_BUNDLE_SIZE value DELTA_PEAMBLE values HAQ TT Timers DL_EPETITION_NUMBE value UL_EPETITION_NUMBE value Annex A (normative): Handling of measurement gaps Annex B (normative): Contention resolution for ACH access Annex C (informative): Intended UE behaviour for DX Timers Annex D (informative): Change history... 88

6 6 TS V ( ) Foreword This Technical Specification has been produced by the 3 rd Generation Partnership Project (). 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.

7 7 TS V ( ) 1 Scope The present document specifies the E-UTA MAC protocol. 2 eferences The following documents contain provisions which, through reference in this text, constitute provisions of the present document. - eferences 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 document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same elease as the present document. [1] T : "Vocabulary for Specifications". [2] TS : "Evolved Universal Terrestrial adio Access (E-UTA); Physical Layer Procedures". [3] TS : Evolved Universal Terrestrial adio Access (E-UTA); adio Link Control (LC) protocol specification. [4] TS : Evolved Universal Terrestrial adio Access (E-UTA); Packet Data Convergence Protocol (PDCP) Specification. [5] TS : Evolved Universal Terrestrial adio Access (E-UTA); Multiplexing and channel coding. [6] TS : Evolved Universal Terrestrial adio Access (E-UTA); Physical layer; Measurements. [7] TS : Evolved Universal Terrestrial adio Access (E-UTA); Physical Channels and Modulation. [8] TS : Evolved Universal Terrestrial adio Access (E-UTA); adio esource Control (C); Protocol specification. [9] TS : "Evolved Universal Terrestrial adio Access (E-UTA); equirements for support of radio resource management". [10] TS : "Evolved Universal Terrestrial adio Access (E-UTA); User Equipment (UE) radio transmission and reception". [11] TS : "Evolved Universal Terrestrial adio Access (E-UTA); Physical layer for relaying operation". [12] TS : "Evolved Universal Terrestrial adio Access (E-UTA); User Equipment (UE) radio access capabilities". [13] TS : "Proximity-based services (ProSe); Stage 2".

8 8 TS V ( ) 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the terms and definitions given in T [1] and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in T [1]. Active Time: Time related to DX operation, as defined in subclause 5.7, during which the MAC entity monitors the PDCCH. mac-contentionesolutiontimer: Specifies the number of consecutive subframe(s) during which the MAC entity shall monitor the PDCCH after Msg3 is transmitted. DX Cycle: Specifies the periodic repetition of the On Duration followed by a possible period of inactivity (see figure below). UE shall monitor PDCCH On Duration Opportunity for DX DX Cycle Figure 3.1-1: DX Cycle drx-inactivitytimer: Except for NB-IoT, 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, it specifies the number of consecutive PDCCH-subframe(s) after the subframe in which the HAQ TT timer or UL HAQ TT timer expires. drx-etransmissiontimer: Specifies the maximum number of consecutive PDCCH-subframe(s) until a DL retransmission is received. drxshortcycletimer: Specifies the number of consecutive subframe(s) the MAC entity shall follow the Short DX cycle. drxstartoffset: Specifies the subframe where the DX Cycle starts. drx-uletransmissiontimer: Specifies the maximum number of consecutive PDCCH-subframe(s) until a grant for UL retransmission is received. HAQ information: HAQ 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 HAQ, the HAQ information also includes HAQ process ID, except for UEs in NB-IoT for which this information is not present. For UL-SCH transmission the HAQ information also includes edundancy Version (V). In case of spatial multiplexing on DL-SCH the HAQ information comprises a set of NDI and TB size for each transport block. HAQ information for SL-SCH and SL-DCH transmissions consists of TB size only. HAQ TT Timer: This parameter specifies the minimum amount of subframe(s) before a DL HAQ retransmission is expected by the MAC entity. Msg3: Message transmitted on UL-SCH containing a C-NTI MAC CE or CCCH SDU, submitted from upper layer and associated with the UE Contention esolution Identity, as part of a random access procedure. NB-IoT: NB-IoT allows access to network services via E-UTA with a channel bandwidth limited to 180 khz. NB-IoT UE: A UE that uses NB-IoT. ondurationtimer: Specifies the number of consecutive PDCCH-subframe(s) at the beginning of a DX Cycle.

9 9 TS V ( ) PDCCH: efers to the PDCCH [7], EPDCCH (in subframes when configured), MPDCCH [2], for an N with - PDCCH configured and not suspended, to the -PDCCH or, for NB-IoT to the NPDCCH. PDCCH period (pp): efers to the interval between the start of two consecutive PDCCH occasions and depends on the currently used PDCCH search space [2]. A PDCCH occasion is the start of a search space and is defined by subframe k0 as specified in section 16.6 of [2]. For an NB-IoT UE, if a timer duration is configured by upper layers in units of a PDCCH period, the calculation of number of PDCCH-subframes for the timer is done by multiplying the number of PDCCH periods with npdcch-numepetitions-a when the UE uses the common search space or by npdcch- Numepetitions when the UE uses the UE specific search space. PDCCH-subframe: efers to a subframe with PDCCH. For a MAC entity not configured with any TDD serving cell(s), this represents any subframe; for a MAC entity configured with at least one TDD serving cell, if a MAC entity is capable of simultaneous reception and transmission in the aggregated cells, this represents the union over all serving cells of downlink subframes and subframes including DwPTS of the TDD UL/DL configuration indicated by tdd- Config [8], except serving cells that are configured with schedulingcellid [8]; otherwise, this represents the subframes where the SpCell is configured with a downlink subframe or a subframe including DwPTS of the TDD UL/DL configuration indicated by tdd-config [8]. For Ns with an N subframe configuration configured and not suspended, in its communication with the E-UTAN, this represents all downlink subframes configured for N communication with the E-UTAN. For SC-PTM reception on a FDD cell, this represents any subframe of the cell except MBSFN subframes; for SC-PTM reception on a TDD cell, this represents the downlink subframes and subframes including DwPTS of the TDD UL/DL configuration indicated by tdd-config [8] of the cell except MBSFN subframes. PDSCH: efers to PDSCH or for NB-IoT to NPDSCH. PACH: efers to PACH or for NB-IoT to NPACH. PACH esource Index: The index of a PACH within a system frame [7] Primary Timing Advance Group: Timing Advance Group containing the SpCell. PUCCH SCell: An SCell configured with PUCCH. PUSCH: efers to PUSCH or for NB-IoT to NPUSCH. ra-pach-maskindex: Defines in which PACHs within a system frame the MAC entity can transmit a andom Access Preamble (see subclause 7.3). A-NTI: The andom Access NTI is used on the PDCCH when andom Access esponse messages are transmitted. It unambiguously identifies which time-frequency resource was utilized by the MAC entity to transmit the andom 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 and Group Destination ID [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 [8]. Sidelink: UE to UE interface for sidelink communication and sidelink discovery. The sidelink corresponds to the PC5 interface as defined in [13]. Sidelink Discovery Gap for eception: 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.

10 10 TS V ( ) Timing Advance Group: A group of Serving Cells that is configured by C and that, for the cells with an UL configured, using the same timing reference cell and the same Timing Advance value. UL HAQ TT Timer: This parameter specifies the minimum amount of subframe(s) before a UL HAQ retransmission grant is expected by the MAC entity. 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 T [1] and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in T [1]. BL BS C-NTI CC-NTI CQI CI eimta eimta-nti E-UTA E-UTAN G-NTI MAC MCG M-NTI MPDCCH LCG NB-IoT NPDCCH NPDSCH NPACH NPUSCH PCell PSCell PH PMI PPPP P-NTI ProSe ptag PTI A-NTI I N NTI SCell SC-FDM SCG SCI SC-N-NTI SC-PTM SC-NTI SI-NTI SL SL-NTI S Bandwidth reduced Low complexity Buffer Status eport Cell NTI Common Control NTI Channel Quality Indicator CSI-S esource Indicator Enhanced Interference Management and Traffic Adaptation Enhanced Interference Management and Traffic Adaptation - NTI Evolved UMTS Terrestrial adio Access Evolved UMTS Terrestrial adio Access Network Group NTI Medium Access Control Master Cell Group MBMS NTI MTC Physical Downlink Control Channel Logical Channel Group Narrow Band Internet of Things Narrowband Physical Downlink Control Channel Narrowband Physical Downlink Shared channel Narrowband Physical andom Access Control Channel Narrowband Physical Uplink Shared channel Primary Cell Primary Secondary Cell Power Headroom eport Precoding Matrix Index ProSe Per-Packet Priority Paging NTI Proximity-based Services Primary Timing Advance Group Precoding Type Indicator andom Access NTI ank Indicator elay Node adio Network Temporary Identifier Secondary Cell Single-Carrier Frequency Division Multiplexing Secondary Cell Group Sidelink Control Information Single Cell Notification NTI Single Cell Point to Multipoint Single Cell NTI System Information NTI Sidelink Sidelink NTI Scheduling equest

11 11 TS V ( ) SS Sounding eference Symbols SpCell Special Cell stag Secondary Timing Advance Group TAG Timing Advance Group TB Transport Block TPC-PUCCH-NTI Transmit Power Control-Physical Uplink Control Channel-NTI TPC-PUSCH-NTI Transmit Power Control-Physical Uplink Shared Channel-NTI 4 General 4.1 Introduction The objective is to describe the MAC architecture and the MAC entity from a functional point of view. Functionality specified for the UE equally applies to the N for functionality necessary for the N. There is also functionality which is only applicable to the N, in which case the specification denotes the N instead of the UE. N-specific behaviour is not applicable to the UE. For TDD operation, UE behaviour follows the TDD UL/DL configuration indicated by tdd- Config unless specified otherwise. 4.2 MAC architecture The description in this sub clause is a model and does not specify or restrict implementations. C is in control of configuration of MAC MAC Entities E-UTA defines two MAC entities; one in the UE and one in the E-UTAN. These MAC entities handle the following transport channels: - Broadcast Channel (BCH); - Downlink Shared Channel(s) (DL-SCH); - Paging Channel (PCH); - Uplink Shared Channel(s) (UL-SCH); - andom Access Channel(s) (ACH); - Multicast Channel(s) (MCH); - Sidelink Broadcast Channel (SL-BCH); - Sidelink Discovery Channel (SL-DCH); - Sidelink Shared Channel (SL-SCH). The exact functions performed by the MAC entities are different in the UE from those performed in the E-UTAN. The N includes both types of MAC entities; one type for communication with UEs and one type for communication with the E-UTAN. In Dual Connectivity, two MAC entities are configured in the UE: one for the MCG and one for the SCG. Each MAC entity is configured by C with a serving cell supporting PUCCH transmission and contention based andom Access. In this specification, the term SpCell refers to such cell, whereas the term SCell refers to other serving cells. The term SpCell either 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. A Timing Advance Group containing the SpCell of a MAC entity is referred to as ptag, whereas the term stag refers to other TAGs.

12 12 TS V ( ) The functions of the different MAC entities in the UE operate independently if not otherwise indicated. The timers and paramenters used in each MAC entity are configured independently if not otherwise indicated. The Serving Cells, C- NTI, radio bearers, logical channels, upper and lower layer entities, LCGs, and HAQ entities considered by each MAC entity refer to those mapped to that MAC entity if not otherwise indicated. If the MAC entity is configured with one or more SCells, there are multiple DL-SCH and there may be multiple UL- SCH and ACH per MAC entity; one DL-SCH and UL-SCH on the SpCell, one DL-SCH, zero or one UL-SCH and zero or one ACH for each SCell. Figure illustrates one possible structure for the UE side MAC entity when SCG is not configured, and it should not restrict implementation. SC- MCCH SC- MTCH Upper layers PCCH MCCH MTCH BCCH B- BCCH CCCH DCCH DTCH MAC-control De Multiplexing Logical Channel Prioritization (UL only) De Multiplexing De Multiplexing HAQ HAQ (De-) Multiplexing andom Access Control Control PCH MCH BCH DL-SCH UL-SCH ACH Lower layer Figure : MAC structure overview, UE side Figure illustrates one possible structure for the UE side MAC entities when MCG and SCG are configured, and it should not restrict implementation. MBMS reception and SC-PTM reception are excluded from this figure for simplicity.

13 13 TS V ( ) Upper layers PCCH BCCH CCCH DCCH DTCH MAC-control BCCH DTCH Upper layers MAC-control Logical Channel Prioritization (UL only) Logical Channel Prioritization (UL only) (De-)Multiplexing Control (De-)Multiplexing Control HAQ andom Access Control HAQHAQ andom Access Control PCH of MCG BCH of MCG DL-SCH of MCG UL-SCH of MCG Lower layer of MCG ACH of MCG BCH of SCG DL-SCH of SCG UL-SCH of SCG Lower layer of SCG ACH of SCG Figure : MAC structure overview with two MAC entities, UE side Figure illustrates one possible structure for the UE side MAC entity when sidelink is configured, and it should not restrict implementation. SBCCH Upper layers STCH MAC-control Logical Channel Prioritization (tx only) (De-)Multiplexing PDU filtering (rx only) Control HAQ HAQ SL-DCH SL-BCH Lower layer SL-SCH Figure : MAC structure overview for sidelink, UE side

14 14 TS V ( ) 4.3 Services Services provided to upper layers This clause describes the different services provided by MAC sublayer to upper layers. - data transfer - radio resource allocation Services expected from physical layer The physical layer provides the following services to MAC: - data transfer services; - signalling of HAQ feedback; - signalling of Scheduling equest; - measurements (e.g. Channel Quality Indication (CQI)). The access to the data transfer services is through the use of transport channels. The characteristics of a transport channel are defined by its transport format (or format set), specifying the physical layer processing to be applied to the transport channel in question, such as channel coding and interleaving, and any service-specific rate matching as needed. 4.4 Functions The following functions are supported by MAC sublayer: - 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 from one or different logical channels from transport blocks (TB) delivered from the physical layer on transport channels; - scheduling information reporting; - error correction through HAQ; - priority handling between UEs by means of dynamic scheduling; - priority handling between logical channels of one MAC entity; - Logical Channel prioritisation; - transport format selection; - radio resource selection for SL. The location of the different functions and their relevance for uplink and downlink respectively is illustrated in Table

15 15 TS V ( ) Table 4.4-1: MAC function location and link direction association. MAC function UE enb Downlink Uplink Sidelink tx Sidelink rx Mapping between logical channels and transport channels X X X X X X X X Multiplexing X X X X X Demultiplexing X X X X X Error correction through HAQ X X X X X X X X Transport Format Selection X X X X X X Priority handling between UEs X X X Priority handling between logical channels of one MAC X X X entity Logical Channel prioritisation X X X Scheduling information reporting X X adio esource Selection X X 4.5 Channel structure 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 LC Transport Channels The transport channels used by MAC are described in Table below. Table : Transport channels used by MAC Transport channel name Acronym Downlink Uplink Sidelink tx Sidelink rx Broadcast Channel BCH X Downlink Shared Channel DL-SCH X Paging Channel PCH X Multicast Channel MCH X Uplink Shared Channel UL-SCH X andom Access Channel ACH X Sidelink Broadcast SL-BCH X X Channel Sidelink Discovery Channel SL-DCH X X Sidelink Shared Channel SL-SCH X X Logical Channels The MAC layer provides data transfer services on logical channels. A set of logical channel types is defined for different kinds of data transfer services as offered by MAC. Each logical channel type is defined by what type of information is transferred. MAC provides the control and traffic channels listed in Table below.

16 16 TS V ( ) Table : Logical channels provided by MAC. Logical channel name Acronym Control channel Traffic channel Broadcast Control Channel BCCH X Bandwidth educed B-BCCH X Broadcast Control Channel Paging Control Channel PCCH X Common Control Channel CCCH X Dedicated Control Channel DCCH X Multicast Control Channel MCCH X Single Cell Multicast Control SC-MCCH X Channel Dedicated Traffic Channel DTCH X Multicast Traffic Channel MTCH X Single-Cell Multicast Traffic SC-MTCH X Channel Sidelink Traffic Channel STCH X Sidelink Broadcast Control Channel SBCCH X Mapping of Transport Channels to Logical Channels The mapping of logical channels on transport channels depends on the multiplexing that is configured by C Uplink mapping The MAC entity is responsible for mapping logical channels for the uplink onto uplink transport channels. The uplink logical channels can be mapped as described in Figure and Table CCCH DCCH DTCH Uplink Logical channels ACH UL-SCH Uplink Transport channels Figure Table : Uplink channel mapping. Transport channel Logical channel CCCH DCCH DTCH UL-SCH X X X ACH Downlink mapping The MAC entity is responsible for mapping the downlink logical channels to downlink transport channels. The downlink logical channels can be mapped as described in Figure and Table

17 17 TS V ( ) MTCH MCCH B- PCCH BCCH BCCH CCCH DCCH DTCH SC- MTCH SC- MCCH Downlink Logical channels MCH PCH BCH DL-SCH Downlink Transport channels Figure Table : Downlink channel mapping. Transport channel BCH PCH DL-SCH MCH Logical channel BCCH X X B-BCCH X PCCH X CCCH X DCCH X DTCH X MCCH X MTCH X SC-MCCH X SC-MTCH X Sidelink mapping The MAC entity is responsible for mapping the sidelink logical channels to sidelink transport channels. The sidelink logical channels can be mapped as described in Figure and Table SBCCH STCH Sidelink Logical channels SL-BCH SL-DCH SL-SCH Sidelink Transport channels Figure Table : Sidelink channel mapping. Transport channel Logical channel STCH SBCCH SL-SCH SL-BCH SL-DCH X X

18 18 TS V ( ) 5 MAC procedures 5.1 andom Access procedure andom Access Procedure initialization The andom Access procedure described in this subclause is initiated by a PDCCH order, by the MAC sublayer itself or by the C sublayer. andom Access procedure on an SCell shall only be initiated by a PDCCH order. If a MAC entity receives a PDCCH transmission consistent with a PDCCH order [5] masked with its C-NTI, and for a specific Serving Cell, the MAC entity shall initiate a andom Access procedure on this Serving Cell. For andom Access on the SpCell a PDCCH order or C optionally indicate the ra-preambleindex and the ra-pach-maskindex, except for NB-IoT where the subcarrier index is indicated; and for andom Access on an SCell, the PDCCH order indicates the ra-preambleindex with a value different from and the ra-pach-maskindex. For the ptag preamble transmission on PACH and reception of a PDCCH order are only supported for SpCell. If the UE is an NB-IoT UE and is configured with a non-anchor carrier, perform the andom Access procedure on the anchor carrier. Before the procedure can be initiated, the following information for related Serving Cell is assumed to be available for UEs other than NB-IoT UEs, BL UEs or UEs in enhanced coverage [8], unless explicitly stated otherwise: - the available set of PACH resources for the transmission of the andom Access Preamble, prach-configindex. - the groups of andom Access Preambles and the set of available andom Access Preambles in each group (SpCell only): The preambles that are contained in andom Access Preambles group A and andom Access Preambles group B are calculated from the parameters numberofa-preambles and sizeofa-preamblesgroupa: If sizeofa-preamblesgroupa is equal to numberofa-preambles then there is no andom Access Preambles group B. The preambles in andom Access Preamble group A are the preambles 0 to sizeofa- PreamblesGroupA 1 and, if it exists, the preambles in andom Access Preamble group B are the preambles sizeofa-preamblesgroupa to numberofa-preambles 1 from the set of 64 preambles as defined in [7]. - if andom Access Preambles group B exists, the thresholds, messagepoweroffsetgroupb and messagesizegroupa, the configured UE transmitted power of the Serving Cell performing the andom Access Procedure, P CMAX, c [10], and the offset between the preamble and Msg3, deltapreamblemsg3, that are required for selecting one of the two groups of andom Access Preambles (SpCell only). - the A response window size ra-esponsewindowsize. - the power-ramping factor powerampingstep. - the maximum number of preamble transmission preambletransmax. - the initial preamble power preambleinitialeceivedtargetpower. - the preamble format based offset DELTA_PEAMBLE (see subclause 7.6). - the maximum number of Msg3 HAQ transmissions maxhaq-msg3tx (SpCell only). - the Contention esolution Timer mac-contentionesolutiontimer (SpCell only). NOTE: The above parameters may be updated from upper layers before each andom Access procedure is initiated. The following information for related Serving Cell is assumed to be available before the procedure can be initiated for NB-IoT UEs, BL UEs or UEs in enhanced coverage [8]: - if the UE is a BL UE or a UE in enhanced coverage: - the available set of PACH resources associated with each enhanced coverage level supported in the Serving Cell for the transmission of the andom Access Preamble, prach-configindex.

19 19 TS V ( ) - the groups of andom Access Preambles and the set of available andom Access Preambles in each group(spcell only): The preambles that are contained in andom Access Preamble groups for each enhanced coverage level, if it exists, are the preambles firstpreamble to lastpreamble. If sizeofa-preamblesgroupa is not equal to numberofa-preambles, andom Access Preambles group B exists for all enhanced coverage levels and is calculated as above. NOTE: If andom Access Preamble group B exists, the enb should ensure that at least one andom Access Preamble is contained in andom Access Preamble group A and andom Access Preamble group B for all enhanced coverage level. - if the UE is a NB-IoT UE: - the available set of PACH resources supported in the Serving Cell, nprach-parameterslist. - for random access resource selection and preamble transmission: - a PACH resource is mapped into an enhanced coverage level. - each PACH resource contains a set of nprach-numsubcarriers subcarriers which can be partitioned into one or two groups for single/multi-tone Msg3 transmission by nprach-subcarriermsg3-angestart. Each group is referred to as a andom Access Preamble group below in the procedure text. - a subcarrier is identified by the subcarrier index in the range: [nprach-subcarrieroffset, nprach-subcarrieroffset + nprach-numsubcarriers -1] - each subcarrier of a andom Access Preamble group corresponds to a andom Access Preamble. - when the subcarrier index is explicitly sent from the enb as part of a PDCCH order ra-preambleindex shall be set to the signalled subcarrier index. - the mapping of the PACH resources into enhanced coverage levels is determined according to the following: - the number of enhanced coverage levels is equal to one plus the number of SP thresholds present in SP-ThresholdsPrachInfoList. - each enhanced coverage level has one PACH resource present in nprach-parameterslist. - enhanced coverage levels are numbered from 0 and the mapping of PACH resources to enhanced coverage levels are done in increasing numepetitionsperpreambleattempt order. - the criteria to select PACH resources based on SP measurement per enhanced coverage level supported in the Serving Cell rsrp-thresholdsprachinfolist. - the maximum number of preamble transmission attempts per enhanced coverage level supported in the Serving Cell maxnumpreambleattemptce. - the number of repetitions required for preamble transmission per attempt for each enhanced coverage level supported in the Serving Cell numepetitionperpreambleattempt. - the configured UE transmitted power of the Serving Cell performing the andom Access Procedure, P CMAX, c [10]. - the A response window size ra-esponsewindowsize and the Contention esolution Timer mac- ContentionesolutionTimer (SpCell only) per enhanced coverage level supported in the Serving Cell. - the power-ramping factor powerampingstep. - the maximum number of preamble transmission preambletransmax-ce. - the initial preamble power preambleinitialeceivedtargetpower. - the preamble format based offset DELTA_PEAMBLE (see subclause 7.6). For NB-IoT the DELTA_PEAMBLE is set to 0.

20 20 TS V ( ) The andom Access procedure shall be performed as follows: - Flush the Msg3 buffer; - set the PEAMBLE_TANSMISSION_COUNTE to 1; - if the UE is an NB-IoT UE, a BL UE or a UE in enhanced coverage: - set the PEAMBLE_TANSMISSION_COUNTE_CE to 1; - if the starting enhanced coverage level, or for NB-IoT the initial number of PACH repetitions, has been indicated in the PDCCH order which initiated the andom Access procedure, or if the starting enhanced coverage level has been provided by upper layers: - the MAC entity considers itself to be in that enhanced coverage level regardless of the measured SP; - else: - if the SP threshold of enhanced coverage level 3 is configured by upper layers in rsrp- ThresholdsPrachInfoList and the measured SP is less than the SP threshold of enhanced coverage level 3 and the UE is capable of enhanced coverage level 3 then: - the MAC entity considers to be in enhanced coverage level 3; - else if the SP threshold of enhanced coverage level 2 configured by upper layers in rsrp- ThresholdsPrachInfoList and the measured SP is less than the SP threshold of enhanced coverage level 2 and the UE is capable of enhanced coverage level 2 then: - the MAC entity considers to be in enhanced coverage level 2; - else if the measured SP is less than the SP threshold of enhanced coverage level 1 as configured by upper layers in rsrp-thresholdsprachinfolist then: - the MAC entity considers to be in enhanced coverage level 1; - else: - the MAC entity considers to be in enhanced coverage level 0; - set the backoff parameter value to 0 ms; - for the N, suspend any N subframe configuration; - proceed to the selection of the andom Access esource (see subclause 5.1.2). NOTE: There is only one andom Access procedure ongoing at any point in time in a MAC entity. If the MAC entity receives a request for a new andom Access procedure 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 andom Access esource selection The andom Access esource selection procedure shall be performed as follows: - If, except for NB-IoT, ra-preambleindex (andom Access Preamble) and ra-pach-maskindex (PACH Mask Index) have been explicitly signalled and ra-preambleindex is not : - the andom Access Preamble and the PACH Mask Index are those explicitly signalled; - else, for NB-IoT, if ra-preambleindex (andom Access Preamble) and PACH resource have been explicitly signalled: - the PACH resource is that explicitly signalled; - if the ra-preambleindex signalled is not :

21 21 TS V ( ) - the andom Access Preamble is set to nprach-subcarrieroffset + (ra-preambleindex modulo nprach- NumSubcarriers), where nprach-subcarrieroffset and nprach-numsubcarriers are parameters in the currently used PACH resource. - else: - select the andom Access Preamble group according to the PACH resource and the support for multitone Msg3 transmission. - randomly select a andom Access Preamble within the selected group. - else the andom Access Preamble shall be selected by the MAC entity as follows: - If Msg3 has not yet been transmitted, the MAC entity shall, for NB-IoT UEs, BL UEs or UEs in enhanced coverage: - expect for NB-IoT, select the andom Access Preambles group and the PACH resource corresponding to the selected enhanced coverage level; - for NB-IoT, select the PACH resource corresponding to the selected enhanced coverage level, and select the andom Access Preambles group corresponding to the PACH resource and the support for multi-tone Msg3 transmission; - If Msg3 has not yet been transmitted, the MAC entity shall, except for BL UEs or UEs in enhanced coverage in case preamble group B does not exists, or for NB-IoT UEs: - if andom Access Preambles group B exists and any of the following events occur: - the potential message size (UL data available for transmission plus MAC header and, where required, MAC control elements) is greater than messagesizegroupa and the pathloss is less than P CMAX,c (of the Serving Cell performing the andom Access Procedure) preambleinitialeceivedtargetpower deltapreamblemsg3 messagepoweroffsetgroupb; - the andom Access procedure was initiated for the CCCH logical channel and the CCCH SDU size plus MAC header is greater than messagesizegroupa; - else: - select the andom Access Preambles group B; - select the andom Access Preambles group A. - else, if Msg3 is being retransmitted, the MAC entity shall: - select the same group of andom Access Preambles as was used for the preamble transmission attempt corresponding to the first transmission of Msg3. - randomly select a andom Access Preamble within the selected group. The random function shall be such that each of the allowed selections can be chosen with equal probability; - except for NB-IoT, set PACH Mask Index to 0. - determine the next available subframe containing PACH permitted by the restrictions given by the prach- ConfigIndex (except for NB-IoT), the PACH Mask Index (except for NB-IoT, see subclause 7.3), physical layer timing requirements [2] and in case of NB-IoT, the subframes occupied by PACH resources related to a higher enhanced coverage level (a MAC entity may take into account the possible occurrence of measurement gaps when determining the next available PACH subframe); - if the transmission mode is TDD and the PACH Mask Index is equal to zero: - if ra-preambleindex was explicitly signalled and it was not (i.e., not selected by MAC): - randomly select, with equal probability, one PACH from the PACHs available in the determined subframe. - else:

22 22 TS V ( ) - else: - randomly select, with equal probability, one PACH from the PACHs available in the determined subframe and the next two consecutive subframes. - determine a PACH within the determined subframe in accordance with the requirements of the PACH Mask Index, if any. - for NB-IoT UEs, BL UEs or UEs in enhanced coverage, select the ra-esponsewindowsize and mac- ContentionesolutionTimer corresponding to the selected enhanced coverage level and PACH. - proceed to the transmission of the andom Access Preamble (see subclause 5.1.3) andom Access Preamble transmission The random-access procedure shall be performed as follows: - set PEAMBLE_ECEIVED_TAGET_POWE to preambleinitialeceivedtargetpower + DELTA_PEAMBLE + (PEAMBLE_TANSMISSION_COUNTE 1) * powerampingstep; - if the UE is a BL UE or a UE in enhanced coverage: - the PEAMBLE_ECEIVED_TAGET_POWE is set to: PEAMBLE_ECEIVED_TAGET_POWE - 10 * log10(numepetitionperpreambleattempt); - if NB-IoT: - for enhanced coverage level 0, the PEAMBLE_ECEIVED_TAGET_POWE is set to: PEAMBLE_ECEIVED_TAGET_POWE - 10 * log10(numepetitionperpreambleattempt) - for other enhanced coverage levels, the PEAMBLE_ECEIVED_TAGET_POWE is set corresponding to the max UE output power; - if the UE is an NB-IoT UE, a BL UE or a UE in enhanced coverage: - instruct the physical layer to transmit a preamble with the number of repetitions required for preamble transmission corresponding to the selected preamble group (i.e., numepetitionperpreambleattempt) using the selected PACH corresponding to the selected enhanced coverage level, corresponding A-NTI, preamble index or for NB-IoT subcarrier index, and PEAMBLE_ECEIVED_TAGET_POWE. - else: - instruct the physical layer to transmit a preamble using the selected PACH, corresponding A-NTI, preamble index and PEAMBLE_ECEIVED_TAGET_POWE andom Access esponse reception Once the andom Access Preamble is transmitted and regardless of the possible occurrence of a measurement gap or a Sidelink Discovery Gap for Transmission or a Sidelink Discovery Gap for eception, the MAC entity shall monitor the PDCCH of the SpCell for andom Access esponse(s) identified by the A-NTI defined below, in the A esponse window which starts at the subframe that contains the end of the preamble transmission [7] plus three subframes and has length ra-esponsewindowsize. If the UE is a BL UE or a UE in enhanced coverage, A esponse window starts at the subframe that contains the end of the last preamble repetition plus three subframes and has length ra- esponsewindowsize for the corresponding coverage level. If the UE is an NB-IoT UE, in case the number of NPACH repetitions is greater than or equal to 64, A esponse window starts at the subframe that contains the end of the last preamble repetition plus 41 subframes and has length ra-esponsewindowsize for the corresponding coverage level, and in case the number of NPACH repetitions is less than 64, A esponse window starts at the subframe that contains the end of the last preamble repetition plus 4 subframes and has length ra-esponsewindowsize for the corresponding coverage level. The A-NTI associated with the PACH in which the andom Access Preamble is transmitted, is computed as: A-NTI= 1 + t_id + 10*f_id

23 23 TS V ( ) where t_id is the index of the first subframe of the specified PACH (0 t_id <10), and f_id is the index of the specified PACH within that subframe, in ascending order of frequency domain (0 f_id< 6) except for NB-IoT UEs, BL UEs or UEs in enhanced coverage. If the PACH resource is on a TDD carrier, the f_id is set to f A, where f A is defined in Section of [7]. For BL UEs and UEs in enhanced coverage, A-NTI associated with the PACH in which the andom Access Preamble is transmitted, is computed as: A-NTI=1+t_id + 10*f_id + 60*(SFN_id mod (Wmax/10)) where t_id is the index of the first subframe of the specified PACH (0 t_id <10), f_id is the index of the specified PACH within that subframe, in ascending order of frequency domain (0 f_id< 6), SFN_id is the index of the first radio frame of the specified PACH, and Wmax is 400, maximum possible A window size in subframes for BL UEs or UEs in enhanced coverage. If the PACH resource is on a TDD carrier, the f_id is set to f A, where f A is defined in Section of [7]. For NB-IoT UEs, the A-NTI associated with the PACH in which the andom Access Preamble is transmitted, is computed as: A-NTI=1+ floor(sfn_id/4) where SFN_id is the index of the first radio frame of the specified PACH. The MAC entity may stop monitoring for andom Access esponse(s) after successful reception of a andom Access esponse containing andom Access Preamble identifiers that matches the transmitted andom Access Preamble. - If a downlink assignment for this TTI has been received on the PDCCH for the A-NTI and the received TB is successfully decoded, the MAC entity shall regardless of the possible occurrence of a measurement gap or a Sidelink Discovery Gap for Transmission or a Sidelink Discovery Gap for eception: - if the andom Access esponse contains a Backoff Indicator subheader: - set the backoff parameter value as indicated by the BI field of the Backoff Indicator subheader and Table 7.2-1, except for NB-IoT where the value from Table is used. - else, set the backoff parameter value to 0 ms. - if the andom Access esponse contains a andom Access Preamble identifier corresponding to the transmitted andom Access Preamble (see subclause 5.1.3), the MAC entity shall: - consider this andom Access esponse reception successful and apply the following actions for the serving cell where the andom Access Preamble was transmitted: - process the received Timing Advance Command (see subclause 5.2); - indicate the preambleinitialeceivedtargetpower and the amount of power ramping applied to the latest preamble transmission to lower layers (i.e., (PEAMBLE_TANSMISSION_COUNTE 1) * powerampingstep); - process the received UL grant value and indicate it to the lower layers; - if ra-preambleindex was explicitly signalled and it was not (i.e., not selected by MAC): - consider the andom Access procedure successfully completed. - else, if the andom Access Preamble was selected by the MAC entity: - set the Temporary C-NTI to the value received in the andom Access esponse message no later than at the time of the first transmission corresponding to the UL grant provided in the andom Access esponse message; - if this is the first successfully received andom Access esponse within this andom Access procedure:

24 24 TS V ( ) - if the transmission is not being made for the CCCH logical channel, indicate to the Multiplexing and assembly entity to include a C-NTI MAC control element in the subsequent uplink transmission; - obtain the MAC PDU to transmit from the "Multiplexing and assembly" entity and store it in the Msg3 buffer. NOTE: NOTE: When an uplink transmission is required, e.g., for contention resolution, the enb should not provide a grant smaller than 56 bits (or 88 bits for NB-IoT) in the andom Access esponse. If within a andom Access procedure, an uplink grant provided in the andom Access esponse for the same group of andom Access Preambles has a different size than the first uplink grant allocated during that andom Access procedure, the UE behavior is not defined. If no andom Access esponse is received within the A esponse window, or if none of all received andom Access esponses contains a andom Access Preamble identifier corresponding to the transmitted andom Access Preamble, the andom Access esponse reception is considered not successful and the MAC entity shall: - if the notification of power ramping suspension has not been received from lower layers: - increment PEAMBLE_TANSMISSION_COUNTE by 1; - if the UE is an NB-IoT UE, a BL UE or a UE in enhanced coverage: - if PEAMBLE_TANSMISSION_COUNTE = preambletransmax-ce + 1: - else: - if the andom Access Preamble is transmitted on the SpCell: - indicate a andom Access problem to upper layers; - if NB-IoT: - consider the andom Access procedure unsuccessfully completed; - if PEAMBLE_TANSMISSION_COUNTE = preambletransmax + 1: - if the andom Access Preamble is transmitted on the SpCell: - indicate a andom Access problem to upper layers; - if the andom Access Preamble is transmitted on an SCell: - consider the andom Access procedure unsuccessfully completed. - if in this andom Access procedure, the andom Access Preamble was selected by MAC: - based on the backoff parameter, select a random backoff time according to a uniform distribution between 0 and the Backoff Parameter Value; - delay the subsequent andom Access transmission by the backoff time; - if the UE is an NB-IoT UE, a BL UE or a UE in enhanced coverage: - increment PEAMBLE_TANSMISSION_COUNTE_CE by 1; - if PEAMBLE_TANSMISSION_COUNTE_CE = maxnumpreambleattemptce for the corresponding enhanced coverage level + 1: - reset PEAMBLE_TANSMISSION_COUNTE_CE; - consider to be in the next enhanced coverage level, if it is supported by the Serving Cell and the UE, otherwise stay in the current enhanced coverage level; - select the andom Access Preambles group, ra-esponsewindowsize, mac-contentionesolutiontimer, and PACH resource corresponding to the selected enhanced coverage level;