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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.
< 38.212 - Table 7.3.1-1: DCI formats >
|
DCI Format |
Usage |
|
Scheduling of PUSCH in one cell |
|
|
Scheduling of PUSCH in one cell |
|
|
Scheduling of PDSCH in one cell DCI format 1_0 with CRC scrambled by C-RNTI |
|
|
Scheduling of PDSCH in one cell |
|
|
Notifying a group of UEs of the slot format |
|
|
Notifying a group of UEs of the PRB(s) and OFDM symbol(s) where UE may assume no transmission is intended for the UE |
|
|
Transmission of TPC commands for PUCCH and PUSCH |
|
|
Transmission of a group of TPC commands for SRS transmissions by one or more UEs |
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.
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. The number of bits and the value is determined as described here. |
|
X |
Carries the row index of the items in pusch_allocationList in RRC |
|
|
Frequency Hopping Flag |
1 |
|
|
Modulation and coding scheme |
5 |
38.214 - 6.1.4 (See this table) |
|
New data indicator |
1 |
|
|
Redundancy version |
2 |
0,1,2,3 |
|
HARQ process number |
4 |
|
|
TPC command for scheduled PUSCH |
2 |
|
|
UL/SUL indicator |
0 or 1 |
0 bit : SUL not figured 1 bit : SUL configured |
< Frequency domain resource assignment >
The number of bits(bit length) for this field is determined by following formula
The meaning of 
varies depending on the search space where DCI_0_0 is transmitted.
- When stransmitted in common search space,
- When stransmitted in UE specific search space and meets following criteria
it indicates the size of the Initial Bandwidth Part
the total number of different DCI sizes monitored per slot <= 4
the total number of different DCI sizes with C-RNTI monitored per slot <= 3
it indicates the size of the Active Bandwidth Part
The value of this field is determined as follows.
MSB bits are used to indicate the frequency offset- = 1 if Frequency-hopping-offsets-set contains two offset values
- = 2 if Frequency-hopping-offsets-set contains four offset values
- Remaining Bits indicates PUSCH RIV
- the whole bits of this field indicates PUSCH RIV
Case 1 : PUSCH hopping = True and Resource allocation type 1
Case 2 : PUSCH hopping = False and Resource allocation type 1
< 38.214 v15.1 - Table 6.1.4.1-1: MCS index table for PUSCH with transform precoding and 64QAM >
|
MCS Index I_MCS |
Modulation Order Qm |
Target code Rate R x 1024 |
Spectral efficiency |
|
0 |
q |
240/ q |
0.2344 |
|
1 |
q |
314/ q |
0.3066 |
|
2 |
2 |
193 |
0.377 |
|
3 |
2 |
251 |
0.4902 |
|
4 |
2 |
308 |
0.6016 |
|
5 |
2 |
379 |
0.7402 |
|
6 |
2 |
449 |
0.877 |
|
7 |
2 |
526 |
1.0273 |
|
8 |
2 |
602 |
1.1758 |
|
9 |
2 |
679 |
1.3262 |
|
10 |
4 |
340 |
1.3281 |
|
11 |
4 |
378 |
1.4766 |
|
12 |
4 |
434 |
1.6953 |
|
13 |
4 |
490 |
1.9141 |
|
14 |
4 |
553 |
2.1602 |
|
15 |
4 |
616 |
2.4063 |
|
16 |
4 |
658 |
2.5703 |
|
17 |
6 |
466 |
2.7305 |
|
18 |
6 |
517 |
3.0293 |
|
19 |
6 |
567 |
3.3223 |
|
20 |
6 |
616 |
3.6094 |
|
21 |
6 |
666 |
3.9023 |
|
22 |
6 |
719 |
4.2129 |
|
23 |
6 |
772 |
4.5234 |
|
24 |
6 |
822 |
4.8164 |
|
25 |
6 |
873 |
5.1152 |
|
26 |
6 |
910 |
5.332 |
|
27 |
6 |
948 |
5.5547 |
|
28 |
1 |
reserved |
|
|
29 |
2 |
reserved |
|
|
30 |
4 |
reserved |
|
|
31 |
6 |
reserved |
|
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 |
|
1,2,3,4 |
Carries the row index of the items in pusch_allocationList in RRC |
|
|
VRB-to-PRB mapping |
1 |
|
| Frequency Hopping Flag |
0,1 |
|
|
Modulation and coding scheme |
5 |
38.214 - 6.1.4 (See this table) |
|
New data indicator |
1 |
|
|
Redundancy version |
2 |
0,1,2,3 |
|
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 |
|
|
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 |
< 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 >
The bit length of this field is determined as follows.
|
Resource Allocation Type |
Mumber of Bits |
|
Resource Allocation Type 0 only |
|
|
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 |
, P is defined in 
The value of this field is determined as follows :
- Resource Allocation Type 0 only : Bitmap determined as described here.
- Resource Allocation Type 1 only : Determined depending on PUSCH Hopping field as follows
- Case 1 : PUSCH hopping = True
- MSB bits are used to indicate the frequency offset
- = 1 if Frequency-hopping-offsets-set contains two offset values
- = 2 if Frequency-hopping-offsets-set contains four offset values
- Remaining Bits indicates PUSCH RIV
- Case 2 : PUSCH hopping = False
- the whole bits of this field indicates PUSCH RIV
< 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-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.
|
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.
|
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 |
||
This is used for the scheduling of PDSCH in one cell.
< DCI format 1_0 with CRC scrambled by C-RNTI >
|
Field (Item) |
Bits |
Reference |
|
Identifier for DCI formats |
1 |
Always set to 1, meaning this is for DL |
|
Frequency domain resource assignment |
Variable |
Variable with DL BWP N_RB |
|
X |
Carries the row index of the items in pdsch_allocationList in RRC |
|
|
VRB-to-PRB mapping |
1 |
According to 38.212 Table 7.3.1.1.2-33 0 : Non-Interleaved 1 : Inverleaved |
|
Modulation and coding scheme |
5 |
|
|
New data indicator |
1 |
|
|
Redundancy version |
2 |
|
|
HARQ process number |
4 |
|
|
Downlink assignment index |
2 |
|
|
TPC command for scheduled PUCCH |
2 |
|
|
PUCCH resource indicator |
3 |
|
|
PDSCH-to-HARQ_feedback timing indicator |
3 |
Row number(index) of K1 |
The meaning of 
varies depending on the search space where DCI_1_0 is transmitted.
When stransmitted in common search space,
it indicates the size of the Initial Bandwidth Part
When stransmitted in UE specific search space and meets following criteria
the total number of different DCI sizes monitored per slot <= 4
the total number of different DCI sizes with C-RNTI monitored per slot <= 3
it indicates the size of the Active Bandwidth Part
< DCI format 1_0 with CRC scrambled by RA-RNTI >
: This is used to schedule RAR (Msg2) in RACH Procedure
|
Field (Item) |
Bits |
Reference |
|
Identifier for DCI formats |
1 |
Always set to 1, meaning this is for DL |
|
Frequency domain resource assignment |
Variable |
Variable with UL BWP N_RB |
|
Time domain resource assignment |
X |
Carries the row index of the items in pdsch_allocationList in RRC |
|
VRB-to-PRB mapping |
1 |
According to 38.212 Table 7.3.1.1.2-33 0 : Non-Interleaved 1 : Inverleaved |
|
Modulation and coding scheme |
5 |
|
|
New data indicator |
1 |
Reserved |
|
Redundancy version |
2 |
Reserved |
|
HARQ process number |
4 |
Reserved |
|
Downlink assignment index |
2 |
Reserved |
|
TPC command for scheduled PUCCH |
2 |
Reserved |
|
PUCCH resource indicator |
3 |
Reserved |
|
PDSCH-to-HARQ_feedback timing indicator |
3 |
Reserved |
The meaning of varies depending on the search space where DCI_1_0 is transmitted.
When stransmitted in common search space in CORESET 0 ,
it indicates the size of the Initial Bandwidth Part
When stransmitted in UE specific search space and meets following criteria
the total number of different DCI sizes monitored per slot <= 4
the total number of different DCI sizes with C-RNTI monitored per slot <= 3
it indicates the size of the Active Bandwidth Part
< DCI format 1_0 with CRC scrambled by TC-RNTI >
: This is used to schedule Contention Resolution (Msg4) in RACH Procedure
|
Field (Item) |
Bits |
Reference |
|
Identifier for DCI formats |
1 |
Always set to 1, meaning this is for DL |
|
Frequency domain resource assignment |
Variable |
Variable with UL BWP N_RB |
|
Time domain resource assignment |
X |
Carries the row index of the items in pdsch_allocationList in RRC |
|
VRB-to-PRB mapping |
1 |
According to 38.212 Table 7.3.1.1.2-33 0 : Non-Interleaved 1 : Inverleaved |
|
Modulation and coding scheme |
5 |
|
|
New data indicator |
1 |
|
|
Redundancy version |
2 |
|
|
HARQ process number |
4 |
|
|
Downlink assignment index |
2 |
Reserved |
|
TPC command for scheduled PUCCH |
2 |
|
|
PUCCH resource indicator |
3 |
|
|
PDSCH-to-HARQ_feedback timing indicator |
3 |
The meaning of varies depending on the search space where DCI_1_0 is transmitted.
When stransmitted in common search space in CORESET 0 ,
it indicates the size of the Initial Bandwidth Part
When stransmitted in UE specific search space and meets following criteria
the total number of different DCI sizes monitored per slot <= 4
the total number of different DCI sizes with C-RNTI monitored per slot <= 3
it indicates the size of the Active Bandwidth Part
This is used for the scheduling of PDSCH in one cell.
|
Field (Item) |
Bits |
Reference |
|
Carrier indicator |
0,3 |
|
|
Identifier for DCI formats |
1 |
Always set to 1, indicating a DL DCI format |
|
Bandwidth part indicator |
0,1,2 |
|
|
Frequency domain resource assignment |
Variable |
Variable with Resource Allocation Type |
|
1,2,3,4 |
Carries the row index of the items in pdsch_allocationList in RRC |
|
|
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 |
Row number(index) of K1 |
|
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 |
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
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 |
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 |
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