Method for transmitting downlink control information in wireless communication system

1. A method for transmitting Downlink Control Information (DCI) by a base station in a wireless communication system, the method comprising:

allocating a resource for data transmission;

transmitting, in a first DCI format, DCI including scheduling information about the allocated resource; and

transmitting data according to the scheduling information, wherein, when the DCI includes scheduling information about multicast/broadcast data, the first DCI format is transmitted in a payload size, which is adjusted to be identical to a payload size of a pre-configured second DCI format, through a Common Search Space (CSS),

wherein, when the DCI includes scheduling information about unicast data, the first DCI format is transmitted in a payload size, which is not adjusted, through a UE-specific Search Space (USS), and

wherein the second DCI format is DCI format 2A and the first DCI format is one of DCI format 2C and DCI format 2D.

2. The method of claim 1 , wherein when the payload size of the first DCI format is adjusted to be identical to the payload size of the second DCI format, it is adjusted by deleting at least one field of a plurality of fields included in the payload of the first DCI format or by reducing a bit size of the at least one field.

3. The method of claim 2 , wherein the second DCI format is DCI format 2A and the first DCI format is DCI format 2C.

4. The method of claim 3 , wherein the first DCI format is scrambled by a Point to Multipoint-Radio Network Temporary Identifier (PTM-RNTI), which is newly defined for multicast/broadcast transmission, and the scrambled first DCI format is transmitted.

5. The method of claim 3 , wherein, when the first and second DCI formats are transmitted in a Frequency Division Duplex (FDD) scheme and a bit size of a Rank field included in a payload of the second DCI format is set to 0 bits, at least one field of a New Data Indicator (NDI) field, a Modulation and Coding Scheme (MCS) 2 field, a Redundancy Version (RV) 2 field, a Hybrid Automatic Repeat Request (HARQ) field, a Transmit Power Control (TPC) field, and a Carrier Indicator Field (CIF) included in the payload of the first DCI format is deleted or a bit size of the at least one field is reduced.

6. The method of claim 3 , wherein, when the first and second DCI formats are transmitted in a Time Division Duplex (TDD) scheme and a bit size of a rank field included in the second DCI format is set to 2 bits, a Sounding Reference Signal (SRS) field is deleted from the payload of the first DCI format and the payload of the first DCI format is transmitted.

7. The method of claim 3 , wherein, when the first and second DCI formats are transmitted in a TDD method and a bit size of a Rank field included in the payload of the second DCI format is set to 0 bits, an SRS field is deleted from the payload of the first DCI format, the payload of the first DCI format is transmitted and, additionally, at least one field of an NDI field, an MCS 2 field, an RV 2 field, an HARQ field, a TPC field, a Downlink Assignment Index (DAI) field, and a CIF is deleted or a bit size of the at least one field is reduced.

8. The method of claim 2 , wherein the second DCI format is DCI format 2 A and the first DCI format is DCI format 2D.

9. The method of claim 8 , wherein, when the first and second DCI formats are transmitted in an FDD scheme and a bit size of a Rank field included in the payload of the second DCI format is set to 2 bits, a PDSCH RE Mapping and Quasi-co-location Indicator (PQI) field are deleted from the payload of the first DCI format and the payload of the first DCI format is transmitted.

10. The method of claim 9 , wherein, when a PTM-RNTI for indicating PQI information included in the deleted PQI field is separately defined, the first DCI format is scrambled by the PTM-RNTI and transmitted.

11. The method of claim 10 , wherein information about a PTM-RNTI corresponding to the PQI information is transmitted via higher layer signaling.

12. The method of claim 8 , wherein, when the first and second DCI formats are transmitted in a TDD scheme and a bit size of a Rank field included in the payload of the second DCI format is set to 2 bits, a PQI field and a SRS field are deleted from the payload of the first DCI format and the payload of the first DCI format is transmitted.

13. The method of claim 8 , wherein, when the first and second DCI formats are transmitted in a TDD scheme and a bit size of a Rank field included in the payload of the second DCI format is set to 0 bits, a PQI field and a SRS field are deleted from the payload of the first DCI format, the payload of the first DCI format is transmitted, and, additionally, at least one field of an NDI field, an MCS 2 field, an RV 2 field, an HARQ field, a TPC field, a DAI field, and a CIF is deleted or a bit size of the at least one field is reduced.

14. The method of claim 13 , wherein, when a PTM-RNTI is separately defined to indicate PQI information included in the deleted PQI field, the first DCI format is scrambled by the PTM-RNTI and transmitted.

15. The method of claim 14 , wherein information about the PTM-RNTI corresponding to the PQI information is transmitted via higher layer signaling.

16. device for transmitting Downlink Control Information (DCI) in a wireless communication system, the method comprising:

a transmitter and a receiver configured to transmit and receive a radio signal; and

a processor configured to control the RF unit transmitter and the receiver,

wherein the base station is configured to:

allocate a resource for data transmission;

transmit, in a first DCI format, DCI including scheduling information about the allocated resource; and

transmit data according to the scheduling information,

wherein, when the DCI includes scheduling information about multicast/broadcast data, the DCI is transmitted in a payload size, which is adjusted to be identical to a payload size of a preset second DCI format, through a Common Search Space (CSS),

wherein, when the DCI includes scheduling information about unicast data, the first DCI format is transmitted in a payload size, which is not adjusted, through a UE-specific Search Space (USS), and

wherein the second DCI format is DCI format 2A and the first DCI format is one of DCI format 2C and DCI format 2D.