Method and apparatus for transmitting and receiving channel status information (CSI) for supporting 256QAM in wireless access system
A method and an evolved Node B (eNB) for receiving Channel Status Information (CSI) in a wireless access system are discussed. The method according to an embodiment includes transmitting a Physical Downlink Shared Channel (PDSCH); and receiving CSI including a Channel Quality Indication (CQI) index associated with the PDSCH. 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. 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. A size of each of the first and the second CQI tables is the same.
1. A method for receiving Channel Status Information (CSI) in a wireless access system, the method performed by an evolved Node B (eNB) and comprising:
transmitting a radio resource control (RRC) signal including Channel Quality Indication (CQI) table information configuring a second CQI table to a second CSI subset;
transmitting a first Physical Downlink Shared Channel (PDSCH) on a first CSI subset and a second PDSCH on the second CSI subset; and
receiving first CSI including a first CQI index associated with the first PDSCH and second CSI including a second CQI index associated with the second PDSCH,
wherein the first CQI index is selected from a first CQI table for supporting up to a 64 Quadrature Amplitude Modulation (QAM) scheme, and the second CQI index is selected from the 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, and
wherein a total number of CQI indexes of each of the first and the second CQI tables is the same, and a size of the first CQI table and a size of the second CQI table are 4 bits.
2. The method according to claim 1 , wherein a number of CQI indices for a 16 QAM scheme of each of the first and the second CQI tables is the same.
3. 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.
4. The method according to claim 1 , wherein, a Transport Block Size (TBS) is determined based on the first CQI table or the second CQI table, the TBS corresponds to the first CQI index or the second CQI index.
5. An evolved Node B (eNB) for receiving Channel Status Information (CSI) in a wireless access system, the eNB comprising:
a receiver,
a transmitter; and
a processor connected with the receiver and the transmitter,
wherein the processor controls the transmitter to:
transmit a radio resource control (RRC) signal including Channel Quality Indication (CQI) table information configuring a second CQI table to a second CSI subset, and
transmit a first Physical Downlink Shared Channel (PDSCH) on a first CSI subset and a second PDSCH on the second CSI subset;
wherein the processor controls the receiver to:
receive first CSI including a first CQI index associated with the first PDSCH and second CSI including a second CQI index associated with the second PDSCH,
wherein the first CQI index is selected from one of a first CQI table for supporting up to a 64 Quadrature Amplitude Modulation (QAM) scheme and the second CQI index is selected from the 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, and
wherein a total number of CQI indexes of each of the first and the second CQI tables is the same, and a size of the first CQI table and a size of the second CQI table are 4 bits.
6. The eNB according to claim 5 , wherein a number of CQI indices for a 16 QAM scheme of the first and the second CQI tables is the same.
7. The eNB according to claim 5 , 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.
8. The eNB according to claim 5 , wherein a Transport Block Size (TBS) is determined based on the first CQI table or the second CQI table, the TBS corresponds to the first CQI index or the second CQI index.