Method and apparatus for transmitting and receiving channel status information (CSI) for supporting 256QAM in wireless access system
A method and apparatus for transmitting and receiving channel status information (CSI) for supporting 256 QAM in a wireless access system are disclosed. A method for transmitting a Channel Quality Indication (CQI) index for 256 QAM (Quadrature Amplitude Modulation) in a wireless access system includes: receiving, by a user equipment (UE), a message including a 256 QAM indicator indicating use of a 256 QAM scheme; performing channel measurement of a downlink channel through which downlink data is transmitted; and transmitting a CQI index in response to the channel measurement result to a base station (BS), wherein the UE simultaneously manages a first CQI feedback table for supporting a legacy modulation scheme and a second CQI feedback table for supporting the 256 QAM scheme.
1. A method for transmitting Channel Status Information (CSI) in a wireless access system, the method performed by a User Equipment (UE) and comprising:
measuring a Channel Quality Indication (CQI) for a Physical Downlink Shared Channel (PDSCH); and
transmitting the CSI including a CQI index corresponding to the CQI,
wherein the CQI index is selected from one of a first CQI table for supporting up to a 64 Quadrature Amplitude Modulation (QAM) scheme and a second CQI table for supporting up to a 256 QAM scheme,
wherein CQI indices 12 to 15 of the first CQI table are used for the 64 QAM scheme and CQI indices 12 to 15 of the second CQI table are used for the 256 QAM scheme,
wherein a number of CQI indices for a 16 QAM scheme of each of the first and the second CQI tables is the same, and
wherein a size of each of the first and the second CQI tables is the same.
2. The method according to claim 1 , wherein the first CQI table is:
CQI index
Modulation
code rate × 1024
efficiency
0
out of range
1
QPSK
78
0.1523
2
QPSK
120
0.2344
3
QPSK
193
0.3770
4
QPSK
308
0.6016
5
QPSK
449
0.8770
6
QPSK
602
1.1758
7
16QAM
378
1.4766
8
16QAM
490
1.9141
9
16QAM
616
2.4063
10
64QAM
466
2.7305
11
64QAM
567
3.3223
12
64QAM
666
3.9023
13
64QAM
772
4.5234
14
64QAM
873
5.1152
15
64QAM
948
5.5547.
3. The method according to claim 1 , wherein a CQI index of the second CQI table is set to 4 bits.
4. The method according to claim 1 , wherein the CSI is transmitted on a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).
5. The method according to claim 1 , wherein the CQI index is selected from the second CQI table when the 256 QAM is supported.
6. The method according to claim 1 , wherein a CQI index of each of the first CQI table and the second CQI table is set to 4 bits.
7. The method according to claim 1 , wherein, the UE derives a Transport Block Size (TBS) corresponding to the CQI index selected from one of the first CQI table for supporting up to a 64 QAM scheme and the second CQI table for supporting up to a 256 QAM scheme.
8. The method according to claim 1 , wherein the CSI is transmitted on a Physical Uplink Shared Channel (PUSCH), and
wherein the CSI includes a rank indication (RI) transmitted on the PUSCH, and, for transmit diversity, the RI is equal to one.
9. A User Equipment (UE) for transmitting Channel Status Information (CSI) in a wireless access system, the UE comprising:
a transmitter; and
a processor configured to:
measure a Channel Quality Indication (CQI) for a Physical Downlink Shared Channel (PDSCH), and
control the transmitter to transmit the CSI including a CQI index corresponding to the CQI,
wherein the CQI index is selected from one of a first CQI table for supporting up to a 64 Quadrature Amplitude Modulation (QAM) scheme and a second CQI table for supporting up to a 256 QAM scheme,
wherein CQI indices 12 to 15 of the first CQI table are used for the 64 QAM and CQI indices 12 to 15 of the second CQI table are used for the 256 QAM scheme,
wherein a number of CQI indices for a 16 QAM scheme of the first and the second CQI tables is the same, and
wherein a size of each of the first and the second CQI tables is the same.
10. The UE according to claim 9 , wherein the first CQI table is:
CQI index
Modulation
code rate × 1024
efficiency
0
out of range
1
QPSK
78
0.1523
2
QPSK
120
0.2344
3
QPSK
193
0.3770
4
QPSK
308
0.6016
5
QPSK
449
0.8770
6
QPSK
602
1.1758
7
16QAM
378
1.4766
8
16QAM
490
1.9141
9
16QAM
616
2.4063
10
64QAM
466
2.7305
11
64QAM
567
3.3223
12
64QAM
666
3.9023
13
64QAM
772
4.5234
14
64QAM
873
5.1152
15
64QAM
948
5.5547.
11. The UE according to claim 9 , wherein a CQI index of the second CQI table is set to 4 bits.
12. The UE according to claim 9 , wherein the CSI is transmitted on a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH).
13. The UE according to claim 9 , wherein the CQI index is selected from the second CQI table when the 256 QAM is supported.
14. The UE according to claim 9 , wherein a CQI index of each of the first CQI table and the second CQI table is set to 4 bits.
15. The UE according to claim 9 , wherein, the UE derives a Transport Block Size (TBS) corresponding to the CQI index selected from one of the first CQI table for supporting up to a 64 QAM scheme and the second CQI table for supporting up to a 256 QAM scheme.
16. The UE according to claim 9 , wherein the CSI is transmitted on a Physical Uplink Shared Channel (PUSCH), and
wherein the CSI includes a rank indication (RI) transmitted on the PUSCH, and, for transmit diversity, the RI is equal to one.