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DCI

 

The main purpose of DCI (Downlink Control Information) is the same as DCI in LTE(I strongly recommend you to read LTE DCI page first if you are not so familiar with what the DCI does). That is, it is a special set of information which schedules downlink data channel (e.g, PDSCH) or uplink data channel (e.g, PUSCH).

 

Followings are the list of DCI types and its contents defined in 38.212 - 7.3 Downlink control information.

 

NOTE : The contents of the table shown here is based on 38.212. This specification is very dry. As any other 3GPP spcecification, it just describes 'what should be done' and does not describe anything on the background story. To get any further technical background, you need to follow through a lot of TDocs. However, unless you are a firmware or DSP engineering implementing the physical channel, it will be very difficult to keep track of all the TDocs. One trick that I would recommend is to go through several latest TDocs not far away from TS (Technical Specification) because those TDocs usually have the summary of past stories and more detailed design concept. I put several TDocs under Reference section that might help you to get some background stories.

 

 

 

Format 0_0

 

This is used for the scheduling of PUSCH in one cell.

 

Field (Item)

Bits

Reference

Identifier for DCI formats

1

 

Frequency domain resource assignment

N

Variable with UL BWP N_RB.

Indicate PRB location within the BWP.

It is expressed in a formula shown here.

Time domain resource assignment

X

 

Frequency Hopping Flag

1

 

Modulation and coding scheme

5

38.214 - 6.1.4 (Not Specified Yet)

New data indicator

1

 

Redundancy version

2

38.214 - 6.1.4 (Not Specified Yet)

HARQ process number

4

 

TPC command for scheduled PUSCH

2

38.213 - Table 7.1.1-1

UL/SUL indicator

0 or 1

0 bit : SUL not figured

1 bit : SUL configured

 

 

< Frequency domain resource assignment >

 

< 38.213 v2.0.0 - Table 7.1.1-1: Mapping of TPC Command Field in DCI format 0_0, DCI format 0_1, or DCI format 2_2, or DCI format 2_3 having CRC parity bits scrambled by TPC-PUSCH-RNTI or TPC-SRS-RNTI, to absolute and accumulated  d_PUSCH,c values >

 

 

 

Format 0_1

 

This is used for the scheduling of PUSCH in one cell.

 

Field (Item)

Bits

Reference

Carrier indicator

3

 

Identifier for DCI formats

1

 

Bandwidth part indicator

0,1,2

Determined by BandwidthPart-Config in higher layer message and 38.212 - Table 7.3.1.1.2-1

Frequency domain resource assignment

Variable

Variable with Resource Allocation Type

Time domain resource assignment

1,2,3,4

 

VRB-to-PRB mapping

1

 
Frequency Hopping Flag

0,1

 

Modulation and coding scheme

5

 

New data indicator

1

 

Redundancy version

2

 

HARQ process number

4

 

1st Downlink assignment index

1,2

 

2nd Downlink assignment index

0,2

 

TPC command for scheduled PUSCH

2

 

SRS resource indicator

Variable

Determined by RRC Parameter SRS-SetUse

Precoding information and number of layers

0,2,3,4,5,6

Determined by ulTxConfig, Number of Antenna ports, PUSCH-tp, ULmaxRank

Antenna ports

2,3,4,5

Determined by PUSCH-tp, DL-DMRS-config-type, DL-DMRS-config-max-len, Rank

SRS request

2

Table 7.3.1.1.2-24

CSI request

0,1,2,3,4,5,6

Determined by ReportTriggerSize in RRC message

CBG transmission information

0,2,4,6,8

Determined by maxCodeBlockGroupPerTransportblock in RRC message

PTRS - DMRS Association

0,2

Determined by UL-PTRS-present, PUSCH-tp in RRC Message

beta_offsetr Indicator

0,2

0 - if uci-on-PUSCH.dynamic = Not Configured

2 - otherwise, see Table 7.3.1.1.2-27

DMRS Sequence Initialization

0,1

0 - if PUSCH-tp=Disabled

1 - if PUSCH-tp=Enabled

UL/SUL Indicator

0,1

0 - bit for UE not configured with SUL in the cell

1 - bit for UEs configured with SUL in the cell

 

 

< BandwidthPart-Config >

BandwidthPart-Config ::= SEQUENCE {

    downlinkBandwidthPartsToReleaseList SEQUENCE (SIZE (1..maxNrofBandwidthParts)) OF BandiwdthPartId   ,

    downlinkBandwidthPartsToAddModList  SEQUENCE (SIZE (1..maxNrofBandwidthParts)) OF BandwidthPart ,

    defaultDownlinkBwp-Id               BandiwdthPartId                                         

    uplinkBandwidthPartsToReleaseList   SEQUENCE (SIZE (1..maxNrofBandwidthParts)) OF BandiwdthPartId   ,

    uplinkBandwidthPartsToAddModList    SEQUENCE (SIZE (1..maxNrofBandwidthParts)) OF BandwidthPart,

    bandwidthPartInactivityTimer        SetupRelease { ENUMERATED {FFS: Value range }}                                              

 

BandwidthPart ::=   SEQUENCE {

    bandwidthPartId     BandiwdthPartId,

    location        INTEGER (0.. maxNrofPhysicalResourceBlocksTimes4)   OPTIONAL,

    bandwidth       INTEGER (1.. maxNrofPhysicalResourceBlocks)     OPTIONAL,

    subcarrierSpacing   ENUMERATED {n0, n1, n2, n3, n4}             OPTIONAL,

    cyclicPrefix        ENUMERATED { extended }                 OPTIONAL,

    directCurrentLocation   INTEGER (0..3299)                   OPTIONAL, -- Cond UplinkOnly

}

 

BandwidthPartId ::=INTEGER (0..maxNrofBandwidthParts-1)

 

 

< 38.212 v2.0.0 - Table 7.3.1.1.2-1: Bandwidth part indicator  >

Value of BWP indicator field

Bandwidth part

1 bit

2 bits

0

0

First bandwidth part configured by higher layers

1

1

Second bandwidth part configured by higher layers

 

10

Third bandwidth part configured by higher layers

 

11

Fourth bandwidth part configured by higher layers

 

 

< Frequency domain resource assignment >

Resource Allocation Type

Mumber of Bits

Resource Allocation Type 0 only

, P is defined in 38.214 Table 6.1.2.2.1-1

Resource Allocation Type 1 only

Resource Allocation Type 0 and Type 1

Bit Length :

      

MSB Indicates Resource Allocation Type

     0 : Resource Allocation Type 0

     1 : Resource Allocation Type 1

 

 

< 38.214-Table 6.1.2.2.1-1: Nominal RBG size P >

Carrier Bandwidth Part Size

Configuration 1

Configuration 2

[1st Range of RBs]

P = [one of {2, 4, 8, 16}]

P = [one of {2, 4, 8, 16}]

[2nd Range of RBs]

P = [one of {2, 4, 8, 16}]

P = [one of {2, 4, 8, 16}]

[3rd Range of RBs]

P = [one of {2, 4, 8, 16}]

P = [one of {2, 4, 8, 16}]

[4th Range of RBs]

P = [one of {2, 4, 8, 16}]

P = [one of {2, 4, 8, 16}]

NOTE : Which RBG(Resource Block Group) size to be used is determined by PUSCH-Config.rbg-Size in RRC message from gNB

 

 

< SRS resource indicator >

SRS-SetUse

Bit Length of SRS Resource Indicator

CodeBook

N_SRS is the number of configured SRS resources in the SRS resource set associated with  SRS-SetUse

NonCodeBook

 

 

 

 

< Precoding information and number of layers >

ulTxConfig

Antenna

PUSCH-tp

ULmaxRank

ULCodebookSubset

Bit Length

Table

NonCodeBook

 

 

 

 

0

 

CodeBook

4 ports

Disabled

2 or 3 or 4

 

4 or 5 or 6

7.3.1.1.2-2

CodeBook

4 ports

Disabled

 

 

2 or 4 or 5

7.3.1.1.2-3

Enabled

1

 

CodeBook

2 ports

 

2

 

3 or 4

7.3.1.1.2-4

CodeBook

2 ports

 

1

 

2 or 3

7.3.1.1.2-5

NOTE : PUSCH-tp indicates PUSCH Transform Precoding. Refer to Transform Precoding section in Waveform Page if you want to know what this is.

 

 

<  Antenna ports >

PUSCH-tp

DL-DMRS-config-type

DL-DMRS-config-max-len

Rank

Bit Lenth

Table

Enabled

1

1

 

2

7.3.1.1.2-6

1

2

 

4

7.3.1.1.2-7

Disabled

1

1

1

3

7.3.1.1.2-8

1

1

2

3

7.3.1.1.2-9

1

1

3

3

7.3.1.1.2-10

1

1

4

3

7.3.1.1.2-11

Disabled

1

2

1

4

7.3.1.1.2-12

1

2

2

4

7.3.1.1.2-13

1

2

3

4

7.3.1.1.2-14

1

2

4

4

7.3.1.1.2-15

Disabled

2

1

1

4

7.3.1.1.2-16

2

1

2

4

7.3.1.1.2-17

2

1

3

4

7.3.1.1.2-18

2

1

4

4

7.3.1.1.2-19

Disabled

2

2

1

5

7.3.1.1.2-20

2

2

2

5

7.3.1.1.2-21

2

2

3

5

7.3.1.1.2-22

2

2

4

5

7.3.1.1.2-23

NOTE : PUSCH-tp indicates PUSCH Transform Precoding. Refer to Transform Precoding section in Waveform Page if you want to know what this is.

 

 

<  PTRS - DMRS Association >

UL-PTRS-present

PUSCH-tp

UL PTRS port

UL-PTRS-ports

Bit Length

Table

OFF

Disabled

 

 

0

N/A

ON

Enabled

 

 

0

N/A

ON

Disabled

 

 

0

N/A

Otherwise

0

1

2

7.3.1.1.2-25

0

2

2

7.3.1.1.2-26

1

2

2

7.3.1.1.2-26

 

 

 

Format 1_0

 

This is used for the scheduling of PDSCH in one cell.

 

Field (Item)

Bits

Reference

Identifier for DCI formats

1

 

Bandwidth part indicator

2

 

Frequency domain resource assignment

Variable

Variable with UL BWP N_RB

     

Time domain resource assignment

X

 

VRB-to-PRB mapping

1

 

Modulation and coding scheme

5

38.214  - Table 5.1.3.1-1: MCS index table 1 for PDSCH

38.214 - Table 5.1.3.1-2: MCS index table 2 for PDSCH

New data indicator

1

 

Redundancy version

2

 

HARQ process number

4

 

Downlink assignment index

2

 

TPC command for scheduled PUCCH

2

 

PUCCH resource indicator

2

 

PDSCH-to-HARQ_feedback timing indicator

3

 

 

 

 

Format 1_1

 

This is used for the scheduling of PDSCH in one cell.

 

Field (Item)

Bits

Reference

Carrier indicator

0,3

 

Identifier for DCI formats

1

 

Bandwidth part indicator

0,1,2

 

Frequency domain resource assignment

Variable

Variable with Resource Allocation Type

Time domain resource assignment

1,2,3,4

 

VRB-to-PRB mapping

0,1

 

PRB bundling size indicator

0,1

 

Rate matching indicator

0,1,2

 

Modulation and coding scheme [TB1]

5

 

New data indicator [TB1]

1

 

Redundancy version [TB1]

2

 

Modulation and coding scheme [TB2]

5

 

New data indicator [TB2]

1

 

Redundancy version [TB2]

2

 

HARQ process number

4

 

Downlink assignment index

0,4

 

TPC command for scheduled PUCCH

2

 

PUCCH resource indicator

2

 

PDSCH-to-HARQ_feedback timing indicator

3

 

Antenna port(s) and number of layers

1,2,3,4,5,6

 

Transmission configuration indication

0,3

 

CSI request

2

 

CBG transmission information

0,2,4,6,8

 

CBG flushing out information

0,1

 

DMRS sequence initialization

1

 

 

 

 

Format 2_0

 

This is used for notifying the slot format.

 

Field (Item)

Bits

Reference

Identifier for DCI formats

1

 

Slot format indicator

Variable

Bit size is determined by RRC message here

 

Slot format indicator : a Bit string indicating Slot format indicator 1, Slot format indicator 2, , Slot format indicator N

 

 

 

Format 2_1

 

This is used for notifying the PRB(s) and OFDM symbol(s) where UE may assume no transmission is intended for the UE.

 

Field (Item)

Bits

Reference

Identifier for DCI formats

1

 

Pre-emption indication

Variable

 

 

 

 

Format 2_2

 

This is used for the transmission of TPC commands for PUCCH, PUSCH

 

Field (Item)

Bits

Reference

Identifier for DCI formats

1

 

TPC command number 1, TPC command number 2,, TPC command number N

Variable

 

 

 

 

Format 2_3

 

This is used for the transmission of a group of TPC commands for SRS transmissions by one or more UEs. Along with a TPC command, a SRS request may also be transmitted.

 

Field (Item)

Bits

Reference

Identifier for DCI formats

1

 

block number 1, block number 2,, block number B

Variable

 
SRS Request

0,2

 
TPC Command Number

2

 

 

 

 

Reference

 

[1] 3GPP TS 38.212 NR;Multiplexing and channel coding   

[2] 3GPP TSG RAN WG1 Meeting #92  : R1-1802117 : Discussion on DCI contents

[3] 3GPP TSG-RAN WG1 #92 : R1-1802905 : Remaining issues of the DCI contents and formats  

[4] 3GPP TSG RAN WG1 Meeting #92 : R1-1801976 : DCI Contents and Formats

[5] 3GPP TSG RAN WG1 Meeting #92 : R1-1802097 : Remaining issues on MIMO related DCI design

[6] 3GPP TSG RAN WG1 Meeting #92 : R1-1802482 : DCI contents and formats

[7] 3GPP TSG RAN WG1 Meeting #92 : R1-1802597 : Remaining issues in DCI contents and formats  

[8] 3GPP TSG RAN WG1 Meeting #92 : R1-1802209 : Remaining issues on DCI contents and formats

[9] 3GPP TSG RAN WG1 Meeting #92 : R1-1801730 : Open issues on DCI contents and formats

[10] 3GPP TSG RAN WG1 Meeting #92 : R1-1801624 : Remaining issues on DCI content