LTE Advanced - DCI                            Home : www.sharetechnote.com

 

 

 

For basic introduction to DCI and Release 8 DCI, refer to DCI page. In this page, I would post on the DCIs that is new in LTE advanced. For easy comparison, I put the table showing both release 8 and release 10 DCIs. You can refer to 3GPP 36.212 5.3.3 Downlink control information for the details.

 

 

DCI Formats in Release 10

 

If you are not working on chipset design or early stage of chipset verification, there wouldn't be many cases where you have to look into DCI details. But understanding DCI details would give you more detailed understanding of LTE physical layer. So in terms of study purpose, it is important to understand DCI details.

 

 

Release 8

Release 10

Format 0

Format 0

Format 1

Format 1

Format 1A

Format 1A

Format 1B

Format 1B

Format 1C

Format 1C

Format 1D

Format 1D

Format 2

Format 2

Format 2A

Format 2A

 

Format 2B

 

Format 2C

Format 3

Format 3

Format 3A

Format 3A

 

Format 4

 

What would be the major difference between Release 8 and Release 10 in terms of DCI format ?

A couple of new DCI format is introduced ? like DCI format 2B,2C and Format 4 ?

Yes. It is a difference. But I think the more important differences is that a new field which is introduced in all Release 10 DCI formats. If you look into the DCI format description in 36.212 and compare the release 8 and release 10. You may find the following difference. In release 10, a new field called 'Carrier Indicator' field which is designed for the scheduling information for multi carrier. If you see in more detail, the bit length of the field is 0 or 3. it means that the field can be obmitted if it is not necessary.

 

 

 

The difference between Release 8 DCI format 0 and Release 10 DCI format 0 is as follows. Note that in Release 10 DCI format 0 can specify multicarrier information in CSI field.

 

One of the out standing difference you see in Release 10 DCI is the existence of 'Carrier Indicator' filed in DCI. But this is not the mandatory field. It may or may not be present in the DCI. Then, question would be how UE can figure out whether the Carrier Indicator field is present or not in the DCI it received ?

The answer is "The existence of Carrier Indicator field in DCI is notified to UE via cif-Presence IE in RRC message."

 

Format 0 (Release 8)

Format 0 (Release 10)

 

Carrier Indicator

Flag for format0/format1A differentiation

Flag for format0/format1A differentiation

Hopping flag

Hopping flag

Resource block assignment(RIV)

Resource block assignment (RIV)

MCS and RV

MCS and RV

NDI (New Data Indicator)

NDI (New Data Indicator)

TPC for PUSCH

TPC for PUSCH

Cyclic shift for DM RS

Cyclic shift for DM RS

UL index (TDD only)

UL index (TDD only)

Downlink Assignment Index (DAI)

Downlink Assignment Index (DAI)

CQI request (1 bit)

CSI request (1 or 2 bits : 2 bit is for multi carrier)

 

SRS request

 

Resource allocation type

 

 

What are new for the new DCI format : Format 2B and 2C ? I created a comparative table for you to see the difference between these new format and the existing field.

 

Format 2 (Rel 10)

Format 2A (Rel 10)

Format 2B (Rel 10)

Format 2C (Rel 10)

Carrier indicator

Carrier indicator

Carrier indicator

Carrier indicator

RA header

RA header

RA header

RA header

Resource block assignment

Resource block assignment

Resource block assignment

Resource block assignment

TPC command for PUCCH

TPC command for PUCCH

TPC command for PUCCH

TPC command for PUCCH

Downlink Assignment Index(TDD only)

Downlink Assignment Index(TDD only)

Downlink Assignment Index(TDD only)

Downlink Assignment Index(TDD only)

HARQ process number

HARQ process number

HARQ process number

HARQ process number

   

Scrambling identity

Antenna ports

Scrambling identity

Number of Layers

   

SRS request(TDD Only)

SRS request(TDD Only)

TB to CW flag

TB to CW flag

TB to CW flag

TB to CW flag

MCS for TB1 MCS for TB1 MCS for TB1 MCS for TB1
NDI for TB1 NDI for TB1 NDI for TB1 NDI for TB1
RV for TB1 RV for TB1 RV for TB1 RV for TB1
MCS for TB2 MCS for TB2 MCS for TB2 MCS for TB2
NDI for TB2 NDI for TB2 NDI for TB2 NDI for TB2
RV for TB2 RV for TB2 RV for TB2 RV for TB2

Precoding information

Precoding information

Precoding information

Precoding information

 

The totally new DCI introduced in Release 10, Format 4, carries the information as shown below.

 

Format 4

Carrier indicator (0 or 3 bits)

Resource block assignment

TPC command for scheduled PUSCH (2 bits)

Cyclic shift for DM RS and OCC index (3 bits)

Downlink Assignment Index (DAI) (2 bits)

CSI request (1 or 2 bits)

SRS request (2 bits)

Resource allocation type (1 bit)

MCS and RV for TB1 (5 bits)

NDI for TB1 (1 bit)

MCS and RV for TB2 (5 bits)

NDI for TB2 (1 bit)

Precoding information and number of layers

 

< DCI 1 Examples > ----------------------------------------------------------------------------------------

 

Example 1 > DCI Format 1 - 20 Mhz, Value = 0x0FC00005DC40

 

Field

Value

Value (Binary)

CarrierIndicator

0 (Dec)

000

RA header

RAType0

0

Resource block assignment

1111110000000000000000000

1111110000000000000000000

MCS

23 (Dec)

10111

HARQ process number

3 (Dec)

011

NDI

1

1

RV

0 (Dec)

00

TPC

01

01

 

Example 2 > DCI Format 1 - 20 Mhz, Value = 0x2FC00005DC00

 

Field

Value

Value (Binary)

CarrierIndicator

1 (Dec)

001

RA header

RAType0

0

Resource block assignment

1111110000000000000000000

1111110000000000000000000

MCS

23 (Dec)

10111

HARQ process number

3 (Dec)

011

NDI

1

1

RV

0 (Dec)

00

TPC

0 (Dec)

00

 

 

< DCI 2A Examples > ----------------------------------------------------------------------------------------

 

Example 1 > DCI Format 2A - 20 Mhz, Value = 0x7E000010BCBC

 

Field

Value

Value (Binary)

RA header

RAType0

0

Resource block assignment

1111110000000000000000000

1111110000000000000000000

TPC command for PUCCH

01

01

HARQ process number

0 (Dec)

000

TB to CW flag

0

0

MCS for TB1

23 (Dec)

10111

NDI for TB1

1

0

RV for TB1

0 (Dec)

00

MCS for TB2

23 (Dec)

10111

NDI for TB2

1

1

RV for TB2

0 (Dec)

00

 

 

 

< DCI 2C Examples > ----------------------------------------------------------------------------------------

 

Example 1 > DCI Format 2C - 10 Mhz, Value = 0x7FFFDC3435C0

 

Field

Value

Value (Binary)

RA header

RAType0

0

Resource block assignment

11111111111111111

11111111111111111

TPC command for PUCCH

01

01

HARQ process number

6 (Dec)

110

Ports-SCID-Number of Layers

0

000

MCS for TB1

26 (Dec)

11010

NDI for TB1

0

0

RV for TB1

0 (Dec)

00

MCS for TB2

26 (Dec)

11010

NDI for TB2

1

1

RV for TB2

3 (Dec)

11

 

 

Example 2 > DCI Format 2C - 10 Mhz, Value = 0x1F3FD4202100

 

Field

Value

Value (Binary)

RA header

RAType0

0

Resource block assignment

00111110011111111

00111110011111111

TPC command for PUCCH

01

01

HARQ process number

2 (Dec)

110

Ports-SCID-Number of Layers

0

000

MCS for TB1

16 (Dec)

10000

NDI for TB1

0

0

RV for TB1

0 (Dec)

00

MCS for TB2

16 (Dec)

10000

NDI for TB2

1

1

RV for TB2

0 (Dec)

00

 

 

Who Schedule Each Component Carriers ?

 

When you have multiple Carriers in Carrier Aggregation, you naturally have a question. That is, who (which carrier) will be schedule resource allocation for each sub carriers ?

There are two types of method we can think of as illustrated below. In one case (Own Scheduling), each component carrier schedules for its own carrier. In the other case (Cross Carrier Scheduling), Primary Compnent Cell (or any specified serving cell) schedules the resource for all the component carriers.

Then you would have another question. How UE knows whether eNB is doing "cross carrier scheduling" or "non cross carrier scheduling" ?

This information is informed to UE via Higher Layer Signaling (RRC Message) as shown below.

 

 

 

< Own (Non Cross Carrier) Scheduling >

 

If Network (eNB) decided to do Own(Non-Cross carrier) Scheduling, it notifies UE using RRC message as shown below.

 

rrcConnectionReconfiguration

    rrc-TransactionIdentifier: 0

    criticalExtensions: c1 (0)

        c1: rrcConnectionReconfiguration-r8 (0)

            rrcConnectionReconfiguration-r8

                radioResourceConfigDedicated

                    physicalConfigDedicated

                nonCriticalExtension

                    lateNonCriticalExtension: <MISSING>

                    nonCriticalExtension

                        nonCriticalExtension

                            sCellToAddModList-r10: 1 item

                                Item 0

                                    SCellToAddMod-r10

                                        sCellIndex-r10: 1

                                        radioResourceConfigDedicatedSCell-r10

                                            physicalConfigDedicatedSCell-r10

                                                nonUL-Configuration-r10

                                                    crossCarrierSchedulingConfig-r10

                                                        schedulingCellInfo-r10: own-r10 (0)

                                                            own-r10

                                                                .... ..0. cif-Presence-r10: False

 

 

< Cross Carrier Scheduling >

 

If Network (eNB) decided to do Cross carrier Scheduling, it notifies UE using RRC message as shown below.

 

rrcConnectionReconfiguration

    rrc-TransactionIdentifier: 0

    criticalExtensions: c1 (0)

        c1: rrcConnectionReconfiguration-r8 (0)

            rrcConnectionReconfiguration-r8

                radioResourceConfigDedicated

                    physicalConfigDedicated

                nonCriticalExtension

                    lateNonCriticalExtension: <MISSING>

                    nonCriticalExtension

                        nonCriticalExtension

                            sCellToAddModList-r10: 1 item

                                Item 0

                                    SCellToAddMod-r10

                                        sCellIndex-r10: 1

                                        radioResourceConfigDedicatedSCell-r10

                                            physicalConfigDedicatedSCell-r10

                                                nonUL-Configuration-r10

                                                    crossCarrierSchedulingConfig-r10

                                                        schedulingCellInfo-r10: other-r10 (1)

                                                            other-r10

                                                                schedulingCellId-r10: 0

                                                                pdsch-Start-r10: 3