3GPP TS 36.321 V8.1.0 (2008-03)
`
`Technical Specification
`
`
`
`3rd Generation Partnership Project;
`Technical Specification Group Radio Access Network;
`Evolved Universal Terrestrial Radio Access (E-UTRA)
`Medium Access Control (MAC) protocol specification
`(Release 8)
`
`The present document has been developed within the 3rd Generation Partnership Project (3GPP TM) and may be further elaborated for the purposes of 3GPP.
`
`
`The present document has not been subject to any approval process by the 3GPP Organizational Partners and shall not be implemented.
`
`This Specification is provided for future development work within 3GPP only. The Organizational Partners accept no liability for any use of this Specification.
`Specifications and reports for implementation of the 3GPP TM system should be obtained via the 3GPP Organizational Partners' Publications Offices.
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`Keywords
`UMTS, radio
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`
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`3GPP
`
`Postal address
`
`3GPP support office address
`650 Route des Lucioles - Sophia Antipolis
`Valbonne - FRANCE
`Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
`
`Internet
`http://www.3gpp.org
`
`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.
`
`© 2008, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC).
`All rights reserved.
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`Contents
`
`Foreword ............................................................................................................................................................5
`1
`Scope........................................................................................................................................................6
`2
`References................................................................................................................................................6
`3
`Definitions and abbreviations...................................................................................................................6
`3.1
`Definitions ......................................................................................................................................................... 6
`3.2
`Abbreviations..................................................................................................................................................... 7
`4
`General .....................................................................................................................................................7
`4.1
`Introduction........................................................................................................................................................ 7
`4.2
`MAC architecture .............................................................................................................................................. 7
`4.2.1
`MAC Entities ............................................................................................................................................... 7
`4.3
`Services.............................................................................................................................................................. 8
`4.3.1
`Services provided to upper layers ................................................................................................................ 8
`4.3.2
`Services expected from physical layer ......................................................................................................... 8
`4.4
`Functions............................................................................................................................................................ 8
`4.5
`Channel structure............................................................................................................................................... 9
`4.5.1
`Transport Channels ...................................................................................................................................... 9
`4.5.2
`Logical Channels.......................................................................................................................................... 9
`4.5.3
`Mapping of Transport Channels to Logical Channels................................................................................ 10
`4.5.3.1
`Uplink mapping.................................................................................................................................... 10
`4.5.3.2
`Downlink mapping ............................................................................................................................... 10
`5
`MAC procedures ....................................................................................................................................11
`5.1
`Random Access procedure............................................................................................................................... 11
`5.1.1
`Random Access Procedure initialization.................................................................................................... 11
`5.1.2
`Random Access Resource selection........................................................................................................... 11
`5.1.3
`Random Access Preamble transmission..................................................................................................... 12
`5.1.4
`Random Access Response reception.......................................................................................................... 12
`5.1.5
`Contention Resolution................................................................................................................................ 13
`5.2
`Maintenance of Uplink Time Alignment......................................................................................................... 14
`5.3
`DL-SCH data transfer ...................................................................................................................................... 14
`5.3.1
`DL Assignment reception........................................................................................................................... 14
`5.3.2
`HARQ operation ........................................................................................................................................ 15
`5.3.2.1
`HARQ Entity........................................................................................................................................ 15
`5.3.2.2
`HARQ process...................................................................................................................................... 15
`5.3.3
`Disassembly and demultiplexing................................................................................................................ 16
`5.4
`UL-SCH data transfer ...................................................................................................................................... 16
`5.4.1
`UL Grant reception .................................................................................................................................... 16
`5.4.2
`HARQ operation ........................................................................................................................................ 16
`5.4.2.1
`HARQ entity......................................................................................................................................... 17
`5.4.2.2
`HARQ process...................................................................................................................................... 17
`5.4.3
`Multiplexing and assembly ........................................................................................................................ 18
`5.4.3.1
`Logical channel prioritization............................................................................................................... 18
`5.4.3.2
`Multiplexing of MAC SDUs ................................................................................................................ 19
`5.4.4
`Scheduling Request.................................................................................................................................... 19
`5.4.5
`Buffer Status Reporting.............................................................................................................................. 19
`5.5
`PCH reception.................................................................................................................................................. 20
`5.6
`BCH reception ................................................................................................................................................. 20
`5.7
`Discontinuous Reception (DRX) ..................................................................................................................... 20
`5.8
`MAC reconfiguration....................................................................................................................................... 21
`5.9
`MAC Reset ...................................................................................................................................................... 21
`5.X
`Handling of unknown, unforeseen and erroneous protocol data...................................................................... 22
`6
`Protocol Data Units, formats and parameters.........................................................................................22
`6.1
`Protocol Data Units.......................................................................................................................................... 22
`6.1.1
`General....................................................................................................................................................... 22
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`MAC PDU (DL-SCH and UL-SCH).......................................................................................................... 22
`6.1.2
`MAC Control Elements.............................................................................................................................. 23
`6.1.3
`Buffer Status Report MAC Control Elements ...................................................................................... 23
`6.1.3.1
`C-RNTI MAC Control Element ........................................................................................................... 24
`6.1.3.2
`DRX Command MAC Control Element............................................................................................... 24
`6.1.3.3
`UE Contention Resolution Identity MAC Control Element ................................................................. 24
`6.1.3.4
`MAC PDU (transparent MAC) .................................................................................................................. 25
`6.1.4
`MAC PDU (Random Access Response) .................................................................................................... 25
`6.1.5
`Formats and parameters ................................................................................................................................... 26
`6.2
`MAC header for DL-SCH and UL-SCH.................................................................................................... 26
`6.2.1
`MAC header for Random Access Response .............................................................................................. 27
`6.2.2
`MAC payload for Random Access Response ............................................................................................ 28
`6.2.3
`Variables and constants..........................................................................................................................28
`7
`RNTI values..................................................................................................................................................... 29
`7.1
`Change history ...............................................................................................30
`Annex A (informative):
`
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`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
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`the first digit:
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`1 presented to TSG for information;
`
`2 presented to TSG for approval;
`
`3 or greater indicates TSG approved document under change control.
`
`y
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`the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
`updates, etc.
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`z
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`the third digit is incremented when editorial only changes have been incorporated in the document.
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`1 Scope
`The present document specifies the E-UTRA MAC protocol.
`
`References
`2
`The following documents contain provisions which, through reference in this text, constitute provisions of the present
`document.
`
`(cid:120) References are either specific (identified by date of publication, edition number, version number, etc.) or
`non-specific.
`
`(cid:120) For a specific reference, subsequent revisions do not apply.
`
`(cid:120) 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]
`
`[2]
`
`3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
`
`3GPP TR 36.213: "E-UTRA; Physical Layer Procedures".
`
`3
`
`Definitions and abbreviations
`
`Definitions
`3.1
`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 that the UE is awake. When DRX is configured by higher layer, this includes the On Duration, the
`time UE is continuously monitoring the PDCCH while the DRX Inactivity Timer has not expired and the time UE is
`continuously monitoring the PDCCH while any DRX Retransmission Timer is running.
`
`Contention Resolution Timer: Specifies the number of consecutive [downlink subframe(s)] during which the UE shall
`monitor the PDCCH after the uplink message containing the C-RNTI MAC control element or the uplink message
`associated with UE Contention Resolution Identity submitted from higher layer 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).
`
`DRX Inactivity Timer: Specifies the number of consecutive downlink subframe(s) during which the UE shall monitor
`the PDCCH after successfully decoding a PDCCH indicating an initial UL or DL user data transmission for this UE.
`
`Figure 3.1-1: DRX Cycle
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`DRX Retransmission Timer: Specifies the maximum number of consecutive downlink subframe(s) the UE shall
`monitor the PDCCH for as soon as a DL retransmission is expected by the UE.
`
`DRX Short Cycle Timer: This parameter specifies the number of consecutive subframe(s)the UE shall follow the short
`DRX cycle after the DRX Inactivity Timer has expired.
`
`HARQ RTT Timer: This parameter specifies the minimum amount of subframe(s) before a DL HARQ retransmission
`is expected by the UE.
`
`On Duration Timer: Specifies the number of consecutive downlink subframe(s) during which the UE shall monitor the
`PDCCH for possible allocations. The On Duration Timer is a part of a DRX Cycle.
`
`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 UE to transmit the Random
`Access preamble.
`
`Abbreviations
`3.2
`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
`C-RNTI
`E-UTRA
`E-UTRAN
`MAC
`RA-RNTI
`RNTI
`SR
`SRS
`
`
`
`Buffer Status Report
`Cell RNTI
`Evolved UMTS Terrestrial Radio Access
`Evolved UMTS Terrestrial Radio Access Network
`Medium Access Control
`Random Access RNTI
`Radio Network Temporary Identifier
`Scheduling Request
`Sounding Reference Symbols
`
`Editor’s note: Check list of abbreviations for duplicates with TR 21.905.
`
`4
`
`General
`
`Introduction
`4.1
`The objective is to describe the MAC architecture and the MAC entity from a functional point of view.
`
`MAC architecture
`4.2
`The description in this sub clause is a model and does not specify or restrict implementations.
`
`RRC is in control of configuration of MAC.
`
`4.2.1 MAC Entities
`E-UTRA defines two MAC entities; one in the UE and one in the E-UTRAN. These MAC entities handle the following
`transport channels:
`
`- Broadcast Channel (BCH)
`
`- Downlink Shared Channel (DL-SCH)
`
`- Paging Channel (PCH)
`
`- Multicast Channel (MCH)
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`- Uplink Shared Channel (UL-SCH)
`
`- Random Access Channel(s) (RACH)
`
`The exact functions performed by the MAC entities are different in the UE from those performed in the E-UTRAN.
`
`4.3
`
`Services
`
`Services provided to upper layers
`4.3.1
`This clause describes the different services provided by MAC sub layer to upper layers.
`
`- Data transfer
`
`- Radio resource allocation
`
`Services expected from physical layer
`4.3.2
`The physical layer provides the following services to MAC:
`
`-
`
`-
`
`-
`
`data transfer services;
`
`signalling of HARQ feedback;
`
`signalling of Scheduling Request;
`
`- 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.
`
`Functions
`4.4
`The following functions are supported by MAC sub layer:
`
`- 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 HARQ;
`
`- Priority handling between UEs by means of dynamic scheduling;
`
`- Priority handling between logical channels of one UE;
`
`- Logical Channel prioritisation;
`
`- Transport format selection;
`
`NOTE: How the multiplexing relates to the QoS of the multiplexed logical channels is FFS.
`
`The location of the different functions and their relevance for uplink and downlink respectively is illustrated in Table
`4.4-1.
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`Multiplexing
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`Demultiplexing
`
`Table 4.4-1: MAC function location and link direction association.
`MAC function
`UE
`eNB
`Downlink
`Mapping between logical channels and transport channels
`X
`
`X
`
`X
`X
`X
`
`
`
`X
`X
`X
`
`X
`
`X
`
`X
`
`X
`
`X
`X
`
`X
`X
`
`X
`X
`
`X
`X
`X
`
`
`X
`
`
`
`Error correction through HARQ
`
`Transport Format Selection
`Priority handling between UEs
`Priority handling between logical channels of one UE
`Logical Channel prioritisation
`Scheduling information reporting
`
`Uplink
`X
`X
`X
`
`
`X
`X
`X
`X
`X
`X
`X
`X
`
`
`
`Channel structure
`4.5
`The MAC sub layer operates on the channels defined below; transport channels are SAPs between MAC and Layer 1,
`logical channels are SAPs between MAC and RLC.
`
`Transport Channels
`4.5.1
`The transport channels used by MAC are described in Table 4.5.1-1 below.
`
`Table 4.5.1-1: 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
`
`Multicast Channel
`MCH
`X
`
`Uplink Shared Channel
`UL-SCH
`
`X
`Random Access Channel
`RACH
`
`X
`
`
`
`Logical Channels
`4.5.2
`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 4.5.2-1 below. When MAC uses the [L1/L2 control
`channel (name FFS)] to indicate radio resource allocation, the RNTI that is mapped on the [L1/L2 control channel
`(name FFS)] depends on the logical channel type.
`
`Table 4.5.2-1: 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
`
`Multicast Control Channel
`MCCH
`X
`
`Dedicated Control Channel
`DCCH
`X
`
`Dedicated Traffic Channel
`DTCH
`
`X
`Multicast Traffic Channel
`MTCH
`
`X
`
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`4.5.3 Mapping of Transport Channels to Logical Channels
`The mapping of logical channels on transport channels depends on the multiplexing that is configured by RRC.
`
`Uplink mapping
`4.5.3.1
`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 4.5.3.1-1 and Table 4.5.3.1-1.
`
`CCCH
`
`DCCH
`
`DTCH
`
`Uplink
`Logical channels
`
`RACH
`
`UL-SCH
`
`Uplink
`Transport channels
`
`Figure 4.5.3.1-1
`
`Table 4.5.3.1-1: Uplink channel mapping.
`Transport channel
`UL-SCH
`
`Logical channel
`CCCH
`DCCH
`DTCH
`
`X
`X
`X
`
`RACH
`
`
`
`Downlink mapping
`4.5.3.2
`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 4.5.3.2-1 and Table 4.5.3.2-1.
`
`Figure 4.5.3.2-1
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`DL-SCH
`
`X
`
`X
`X
`X
`X
`X
`
`Table 4.5.3.2-1: Downlink channel mapping.
`Transport channel
`BCH
`PCH
`MCH
`
`Logical channel
`BCCH
`PCCH
`CCCH
`MCCH
`DCCH
`DTCH
`MTCH
`
`
`X
`
`
`
`
`
`
`
`
`
`X
`
`
`X
`
`X
`
`
`
`
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`MAC procedures
`
` 5
`
`
`
`5.1
`
`Random Access procedure
`
`Random Access Procedure initialization
`5.1.1
`The Random Access procedure described in this subclause is initiated upon request from higher layer, a PDCCH order
`or by the MAC sublayer itself.
`
`Before the procedure can be initiated, the following information is assumed to be available:
`
`- The available set of PRACH resources for the transmission of the Random Access Preamble and their corresponding
`RA-RNTIs.
`
`- The groups of Random Access Preambles and the set of available Random Access Preambles in each group.
`
`- The thresholds required for selecting one of the two groups of Random Access Preambles.
`
`- The parameters required to derive the TTI window described in subclause 5.1.4.
`
`- The power-ramping factor POWER_RAMP_STEP [integer (cid:149) 0].
`
`- The parameter PREAMBLE_TRANS_MAX [integer > 0].
`
`- The initial preamble power PREAMBLE_INITIAL_POWER.
`
`[Note that the above parameters may be updated from higher layers before each Random Access procedure is initiated.]
`
`The Random Access procedure shall be performed as follows:
`
`- Set the PREAMBLE_TRANSMISSION_COUNTER to 1;
`
`- proceed to the selection of the Random Access Resource (see subclause 5.1.2).
`
`Random Access Resource selection
`5.1.2
`The Random Access Resource procedure shall be performed as follows:
`
`
`
`If the Random Access Preamble and PRACH resource are explicitly signalled and its expiration time was
`configured and has not expired
`
`-
`
`the UE can directly proceed to its transmission (see subclause 5.1.3).
`
`- Else the Random Access Preamble shall be selected by the UE as follows:
`
`- depending on the size of the message to be transmitted on the UL or the requested resource blocks [FFS] [the
`selection also depends on radio conditions], select one of the two groups of Random Access Preambles
`configured by RRC;
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`randomly select a Random Access Preamble within the selected group. The random function shall be such
`that each of the allowed selections can be chosen with equal probability;
`
`if more than one PRACH resources are available in the same subframe (TDD), randomly select one. The
`random function shall be such that each of the allowed selections can be chosen with equal probability;
`
`- proceed to the transmission of the Random Access Preamble (see subclause 5.1.3).
`
`Random Access Preamble transmission
`5.1.3
`Editor’s note: The actual generation of the Random Access sequence is performed in 36.211.
`
`The random-access procedure shall be performed as follows:
`
`[- Set the parameter PREAMBLE_TRANSMISSION_POWER to PREAMBLE_INITIAL_POWER +
`(PREAMBLE_TRANSMISSION_COUNTER-1) * POWER_RAMP_STEP.]
`
`[- If the PREAMBLE_TRANSMISSION_POWER is below the minimum power level, set the
`PREAMBLE_TRANSMISSION_POWER to the minimum power level.]
`
`[- If the PREAMBLE_TRANSMISSION_POWER is above the maximum power level, set the
`PREAMBLE_TRANSMISSION_POWER to the maximum power level.]
`
`- determine the next available Random Access occasion
`
`-
`
`Instruct the physical layer to transmit a preamble using the selected PRACH resource, corresponding RA-RNTI,
`preamble index and PREAMBLE_TRANSMISSION_POWER.
`
`Random Access Response reception
`5.1.4
`Once the Random Access Preamble is transmitted, the UE shall monitor the [PDCCH] in the TTI window
`[RA_WINDOW_BEGIN—RA_WINDOW_END] for Random Access Response(s). The UE may stop monitoring for
`Random Access Response(s) after successful reception of a Random Access Response corresponding to the Random
`Access Preamble transmission.
`
`-
`
`If notification of a reception of the Random Access Response is received from lower layers, the UE shall:
`
`-
`
`if the Random Access Response contains an Overload Indicator
`
`- update the backoff parameter value in the UE
`
`- else the UE shall update the backoff parameter to the value [0],
`
`-
`
`if the Random Access Response contains a Random Access Preamble identifier corresponding to the
`transmitted Random Access Preamble (see subclause 5.1.3)
`
`-
`
`the UE shall:
`
`- consider this Random Access Response reception successful;
`
`- process the received Timing Alignment value (see subclause 5.2);
`
`-
`
`-
`
`-
`
`-
`
`if an UL grant was received, process the UL grant value;
`
`if the UE does not have a C-RNTI, Temporary C-RNTI shall be set to the value received in the
`Random Access Response message no later than at the time of the first transmission corresponding to
`the UL grant provided in the Random Access Response message;
`
`If the UE is in RRC_CONNECTED state [except for RLF] and the Random Access Preamble was
`selected by MAC, a C-RNTI MAC control element shall be included in the subsequent uplink
`transmission;
`
`if the UE is in RRC_IDLE state [or RLF], provide an indication to the higher layers that the procedure
`was successful.
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`If no Random Access Response is received within the TTI window [RA_WINDOW_BEGIN—RA_WINDOW_END],
`or if all received Random Access Responses contain Random Access Preamble identifiers that do not match the
`transmitted Random Access Preamble, the Random Access Response reception is considered not successful and the UE
`shall:
`
`-
`
`If the PREAMBLE_TRANSMISSION_COUNTER is less than PREAMBLE_TRANS_MAX
`
`-
`
`-
`
`increment PREAMBLE_TRANSMISSION_COUNTER by 1;
`
`if in this Random Access procedure:
`
`-
`
`-
`
`the Random Access Preamble was selected by MAC; or
`
`the Random Access Preamble and PRACH resource were explicitly signalled and will expire before the
`next available Random Access occasion:
`
`- based on the backoff parameter stored in the UE since the Random Access procedure initialization
`(see subclause 5.1.1), compute and apply a backoff value indicating when a new Random Access
`transmission shall be attempted;
`
` - proceed to the selection of a Random Access Resource (see subclause 5.1.2).
`
`- Else if PREAMBLE_TRANSMISSION_COUNTER is equal to PREAMBLE_TRANS_MAX
`
`-
`
`if the UE is in RRC_IDLE state [or RLF], indicate to the higher layer that the random access procedure
`failed.
`
`Editor’s note: Whether error conditions are specified is FFS.
`
`Contention Resolution
`5.1.5
`Contention Resolution is based on C-RNTI on [PDCCH] and UE Contention Resolution Identity on DL-SCH. The UE
`Contention Resolution Identity is informed by higher layer, when higher layer initiates Random Access procedure.
`
`Once the uplink message containing the C-RNTI MAC control element or the uplink message including CCCH is
`transmitted, the UE shall:
`
`-
`
`start the Contention Resolution Timer;
`
`- monitor the [PDCCH] until the Contention Resolution Timer expires.
`
`-
`
`If notification of a reception of a [PDCCH] transmission is received from lower layers, the UE shall:
`
`-
`
`if the C-RNTI MAC control element was included in uplink message and the [PDCCH] transmission is
`addressed to its C-RNTI:
`
`- consider this Contention Resolution successful and provide an indication to the higher layers;
`
`-
`
`stop the Contention Resolution Timer.
`
`- else if the uplink message includes CCCH and the [PDCCH] transmission is addressed to its Temporary C-
`RNTI:
`
`-
`
`if the MAC PDU is successfully decoded:
`
`-
`
`-
`
`-
`
`stop the Contention Resolution Timer.
`
`if the MAC PDU contains a UE Contention Resolution Identity MAC control element; and
`
`if the UE Contention Resolution Identity included in the MAC control element matches the UE
`Contention Resolution Identity provided by higher layer
`
`- consider this Contention Resolution successful and finish the disassembly and demultiplexing of the
`MAC PDU.
`
`- else
`
`3GPP
`
`13
`
`

`
`Release 8
`
`14
`
`3GPP TS 36.321 V8.1.0 (2008-03)
`
`- consider this Contention Resolution not successful, discard the successfully decoded MAC PDU and
`provide an indication to the higher layers.
`
`-
`
`If the Contention Resolution Timer expires
`
`-
`
`if the C-RNTI MAC control element was used in uplink message and no [PDCCH] transmission addressed to
`its C-RNTI is received, the Contention Resolution is considered not successful and the UE shall:
`
`-
`
`If the PREAMBLE_TRANSMISSION_COUNTER is less than PREAMBLE_TRANS_MAX
`
`-
`
`increment PREAMBLE_TRANSMISSION_COUNTER by 1;
`
`- based on the backoff parameter stored in the UE since the Random Access procedure initialization
`(see subclause 5.1.1), compute and apply a backoff value indicating when a new Random Access
`transmission shall be attempted;
`
`- proceed to the selection of a Random Access Resource (see subclause 5.1.2).
`
`-
`
`if the uplink message includes CCCH and no [PDCCH] transmission addressed to its Temporary C-RNTI is
`received:
`
`- consider this Contention Resolution not successful and provide an indication to the higher layers.
`
`Maintenance of Uplink Time Alignment
`5.2
`The UE has a configurable Time Alignment Timer. The Time Alignment Timer is valid only in the cell for which it was
`configured and started.
`
`If the Time Alignment Timer has been configured, the UE shall:
`
`- when a Time Alignment Command is received:
`
`- apply the Time Alignment Command;
`
`-
`
`start the Time Alignment Timer (if it is not running) or restart the Time Alignment Timer (if it was already
`running)
`
`- when the Time Alignment Timer has expired or is not running:
`
`- prior to any uplink transmission, use the Random Access procedure in order to obtain uplink Time Alignment
`
`- when the Time Alignment Timer expires:
`
`-
`
`-
`
` release all PUCCH resources;
`
`release any assigned SRS resources.
`
`DL-SCH data transfer
`5.3
`Editor’s note: Current text applies to, at least, FDD.
`
`DL Assignment reception
`5.3.1
`Editor’s note: A downlink assignment can relate to one or two (MIMO) TBs. It is FFS how this information is
`presented to MAC.
`
`Editor’s note: