Method and apparatus for transmitting and receiving downlink control information
The present disclosure relates to a method and an apparatus for transmitting and receiving DCI for supporting 256QAM. Particularly, the method for receiving DCI by a user equipment, may include: transmitting, to a base station, channel state information including information obtained by measuring a channel quality state; receiving, from the base station, the DCI including an MCS index value selected based on the channel state information in a predetermined MCS index table including an MCS index value corresponding to a 256QAM modulation method; and identifying modulation information on downlink data on the basis of the selected MCS index value.
1. A method for receiving downlink control information by a user equipment, the method comprising:
transmitting, to a base station, channel state information including information obtained by measuring a channel quality state;
receiving, from the base station, the downlink control information including a Modulation and Coding Scheme (MCS) index value selected based on the channel state information in a predetermined MCS index table including at least one MCS index value corresponding to a 256-state Quadrature Amplitude Modulation (256QAM) modulation method;
identifying modulation information on downlink data on the basis of the selected MCS index value; and
demodulating the downlink data received from the base station, using the identified modulation information,
wherein the predetermined MCS index table comprises:
four MCS index values for Hybrid Automatic Repeat reQuest (HARQ) retransmission; and
28 MCS index values for HARQ initial transmission.
2. The method of claim 1 , wherein the predetermined MCS index table comprises:
five MCS index values corresponding to a Quadrature Phase Shift Keying (QPSK) modulation method;
six MCS index values corresponding to a 16QAM modulation method;
nine MCS index values corresponding to a 64QAM modulation method; and
eight MCS index values corresponding to the 256QAM modulation method.
3. The method of claim 1 , wherein one of the MCS index values corresponding to the 256QAM modulation method is configured to have transmission efficiency identical to maximum transmission efficiency in an MCS index table where a maximum modulation order is set to 6.
4. The method of claim 1 , wherein one of the MCS index values corresponding to the 256QAM modulation method is configured to have a value of a coding rate identical to a coding rate having maximum transmission efficiency in an MCS index table where a maximum modulation order is set to 6.
5. The method of claim 1 , wherein the predetermined MCS index table is formed to have the MCS index values corresponding to the 256QAM modulation method and each of the MCS index values for the 256QAM modulation method is associated with a coding rate defined in a table below:
MCS
Coding rate
Modulation
index value
(R = code rate * 1024)
method
21
711
256QAM
22
754
256QAM
23
797
256QAM
24
841
256QAM
25
885
256QaM
26
916.5
256QAM
27
948
256QAM.
6. The method of claim 1 , wherein the predetermined MCS index table is formed to have the MCS index values corresponding to the 256QAM modulation method, and each of the MCS index values for the 256QAM is associated with transmission efficiency defined in a table below:
MCS
Transmission
Modulation
index value
efficiency
method
21
5.5547
256QAM
22
5.8906
256QAM
23
6.2266
256QAM
24
6.5703
256QaM
25
6.9141
256QAM
26
7.1602
256QAM
27
7.4063
256QAM.
7. A method for transmitting downlink control information by a base station, the method comprising:
receiving, from a user equipment, channel state information including information obtained by measuring a channel quality state;
selecting a Modulation and Coding Scheme (MCS) index value on the basis of the channel state information in a predetermined MCS index table including at least one MCS index value corresponding to a 256-state Quadrature Amplitude Modulation (256QAM) modulation method;
creating the downlink control information including the selected MCS index value; and
transmitting the downlink control information to the user equipment such that the user equipment demodulates downlink data using modulation information identified from the downlink control information,
wherein the predetermined MCS index table comprises:
four MCS index values for Hybrid Automatic Repeat reQuest (HARQ) retransmission; and
28 MCS index values for HARQ initial transmission.
8. The method of claim 7 , wherein the MCS index table comprises:
five MCS index values corresponding to a Quadrature Phase Shift Keying (QPSK) modulation method;
six MCS index values corresponding to a 16QAM modulation method;
nine MCS index values corresponding to a 64QAM modulation method; and
eight MCS index values corresponding to the 256QAM modulation method.
9. The method of claim 7 , wherein one of the MCS index values corresponding to the 256QAM modulation method is configured to have transmission efficiency identical to maximum transmission efficiency in an MCS index table where a maximum modulation order is set to 6.
10. The method of claim 7 , wherein one of the MCS index values corresponding to the 256QAM modulation method is configured to have a value of a coding rate identical to a coding rate having maximum transmission efficiency in an MCS index table where a maximum modulation order is set to 6.
11. The method of claim 7 , wherein the predetermined MCS index table is formed to have the MCS index values corresponding to the 256QAM modulation method and each of the MCS index values is associated with a coding rate defined in a table below:
MCS
Coding rate
Modulation
index value
(R = code rate*1024)
method
21
711
256QAM
22
754
256QAM
23
797
256QAM
24
841
256QAM
25
885
256QaM
26
916.5
256QAM
27
948
256QAM.
12. The method of claim 7 , wherein the predetermined MCS index table is formed to have the MCS index values corresponding to the 256QAM modulation method, and each of the MCS index values for the 256QAM modulation method is associated with transmission efficiency defined in a table below:
MCS
Transmission
Modulation
index value
efficiency
method
21
5.5547
256QAM
22
5.8906
256QAM
23
6.2266
256QAM
24
6.5703
256QaM
25
6.9141
256QAM
26
7.1602
256QAM
27
7.4063
256QAM.
13. A user equipment for receiving downlink control information, the user equipment comprising:
a transmitter configured to transmit, to a base station, channel state information including information obtained by measuring a channel quality state;
a receiver configured to receive, from the base station, a downlink control information including a Modulation and Coding Scheme (MCS) index value selected based on the channel state information in a predetermined MCS index table including at least one MCS index value corresponding to a 256-state Quadrature Amplitude Modulation (256QAM) modulation method; and
a controller configured (i) to identify modulation information on downlink data based on the selected MCS index value and (ii) to demodulate the downlink data received from the base station, using the identified modulation information,
wherein the predetermined MCS index table comprises:
four MCS index values for Hybrid Automatic Repeat reQuest (HARQ) retransmission; and
28 MCS index values for HARQ initial transmission.
14. The user equipment of claim 13 , wherein the MCS index table comprises:
five MCS index values corresponding to a Quadrature Phase Shift Keying (QPSK) modulation method;
six MCS index values corresponding to a 16QAM modulation method;
nine MCS index values corresponding to a 64QAM modulation method; and
eight MCS index values corresponding to the 256QAM modulation method.
15. The user equipment of claim 13 , wherein one of the MCS index values corresponding to the 256QAM modulation method is configured to have transmission efficiency identical to maximum transmission efficiency in an MCS index table where a maximum modulation order is set to 6.
16. The user equipment of claim 15 , wherein one of the MCS index values corresponding to the 256QAM modulation method is configured to have a value of a coding rate identical to a coding rate having maximum transmission efficiency in an MCS index table where a maximum modulation order is set to 6.
17. The user equipment of claim 13 , wherein the predetermined MCS index table is formed to have the MCS index values corresponding to the 256QAM modulation method, and each of the MCS index values for the 256QAM modulation method is associated with a coding rate defined in a table below:
MCS
Coding rate
Modulation
index value
(R = code rate * 1024)
method
21
711
256QAM
22
754
256QAM
23
797
256QAM
24
841
256QAM
25
885
256QaM
26
916.5
256QAM
27
948
256QAM.
18. The user equipment of claim 13 , wherein the predetermined MCS index table is formed to have the MCS index values corresponding to the 256QAM modulation method, and each of the MCS index values for the 256QAM modulation method is associated with transmission efficiency defined in a table below:
MCS
Transmission
Modulation
index value
efficiency
method
21
5.5547
256QAM
22
5.8906
256QAM
23
6.2266
256QAM
24
6.5703
256QaM
25
6.9141
256QAM
26
7.1602
256QAM
27
7.4063
256QAM.