Method for transmitting and receiving the channel state information and apparatus thereof
The present disclosure relates to an apparatus and a method for transmitting and receiving channel state information of a User Equipment that supports 256-state quadrature amplitude modulation (256QAM). The method may include: receiving a reference signal for measuring channel quality from a base station; measuring the channel quality based on the reference signal, and selecting a CQI index value from a predetermined CQI index table including CQI index values for 256QAM modulation, based on the measurement result of the channel quality; and transmitting channel state information including the selected CQI index value to the base station.
1. A method for transmitting channel state information by a User Equipment (UE), the method comprising:
receiving a reference signal for measuring channel quality from a base station;
measuring the channel quality based on the reference signal, and selecting a channel quality indicator (CQI) index value from a predetermined CQI index table including CQI index values for 256 quadrature amplitude modulation (QAM) modulation, based on the measurement result of the channel quality; and
transmitting channel state information including the selected CQI index value to the base station,
wherein:
one of the CQI index values for 256QAM modulation is set to a code rate value determined based on a SNR interval calculated using a minimum SNR and a maximum SNR;
the minimum SNR is a required SNR of a CQI index having a maximum code rate value among CQI index values for 64QAM modulation of the CQI index table; and
the maximum SNR is a required SNR of a CQI index having the maximum code rate value among CQI index values for 256QAM modulation of the CQI index table.
2. The method of claim 1 , wherein the CQI index table includes three CQI index values for QPSK modulation, three CQI index values for 16QAM modulation, five CQI index values for 64QAM modulation, and four CQI index values for 256QAM modulation.
3. The method of claim 1 , wherein one of the CQI index values for 256QAM modulation is configured to have a code rate value that supports a same transmission efficiency as a maximum transmission efficiency of a CQI index table that excludes CQI index values for 256QAM modulation.
4. The method of claim 3 , wherein the code rate value is calculated to be 711 using “code rate×1024”.
5. The method of claim 1 , wherein one of the CQI index values for 256QAM modulation is configured to have a same code rate value as the code rate value having a maximum transmission efficiency of a CQI index table that exclude CQI index values for 256QAM modulation.
6. The method of claim 5 , wherein the code rate value is defined as “code rate×1024,” and the code rate value has 948.
7. The method of claim 1 , wherein:
the SNR interval is calculated by subtracting the minimum SNR from the maximum SNR and then dividing the subtraction result by 4; and
the code rate value of one of the CQI index values for 256QAM modulation is defined as “code rate×1024” and the code rate value is 797.
8. The method of claim 1 , wherein the CQI index table is configured to include required SNRs between adjacent CQI index values in three CQI index values for QPSK modulation, three CQI index values for 16QAM modulation, and five CQI index values for 64QAM modulation, respectively, to have same difference within a predetermined error rate, as shown in a table below
CQI index
modulation
code rate x 1024
efficiency
0
out of range
1
QPSK
78
0.1523
2
QPSK
193
0.3770
3
QPSK
449
0.8770
4
16QAM
378
1.4766
5
16QAM
490
1.9141
6
16QAM
616
2.4063
7
64QAM
466
2.7305
8
64QAM
567
3.3223
9
64QAM
666
3.9023
10
64QAM
772
4.5234
11
64QAM
873
5.1152.
9. A method for receiving channel state information by a base station, the method comprising:
creating a reference signal for measuring channel quality;
transmitting the reference signal to a User Equipment (UE); and
receiving channel state information including a channel quality indicator (CQI) index selected from a predetermined CQI index table including CQI index values for 256 quadrature amplitude modulation (QAM) modulation, based on a measurement result of the channel quality, from the User Equipment,
wherein:
one of the CQI index values for 256QAM modulation is set to a code rate value determined based on a SNR interval calculated using a minimum SNR and a maximum SNR;
the minimum SNR is a required SNR of a CQI index having a maximum code rate value among CQI index values for 64QAM modulation of the CQI index table; and
the maximum SNR is a required SNR of a CQI index having the maximum code rate value among CQI index values for 256QAM modulation of the CQI index table.
10. The method of claim 9 , wherein the CQI index table includes three CQI index values for QPSK modulation, three CQI index values for 16QAM modulation, five CQI index values for 64QAM modulation, and four CQI index values for 256QAM modulation.
11. The method of claim 9 , wherein one of the CQI index values for 256QAM modulation is configured to have a code rate value that supports a same transmission efficiency as a maximum transmission efficiency of a CQI index table that excludes CQI index values for 256QAM modulation.
12. The method of claim 11 , wherein the code rate value is calculated to be 711 using “code rate×1024”.
13. The method of claim 9 , wherein one of the CQI index values for 256QAM modulation is configured to have a same code rate value as the code rate value having a maximum transmission efficiency of a CQI index table that excludes CQI index values for 256QAM modulation.
14. The method of claim 13 , wherein the code rate value is defined as “code rate×1024,” and the code rate value has 948.
15. The method of claim 9 , wherein:
the SNR interval is calculated by subtracting the minimum SNR from the maximum SNR and then dividing the subtraction result by 4; and
the code rate value of one of the CQI index values for 256QAM modulation is defined as “code rate×1024” and the code rate value is 797.
16. The method of claim 9 , wherein the CQI index table is configured to include required SNRs between adjacent CQI index values in three CQI index values for QPSK modulation, three CQI index values for 16QAM modulation, and five CQI index values for 64QAM modulation, respectively, to have same difference within a predetermined error rate, as shown in a table below
CQI index
modulation
code rate x 1024
efficiency
0
out of range
1
QPSK
78
0.1523
2
QPSK
193
0.3770
3
QPSK
449
0.8770
4
16QAM
378
1.4766
5
16QAM
490
1.9141
6
16QAM
616
2.4063
7
64QAM
466
2.7305
8
64QAM
567
3.3223
9
64QAM
666
3.9023
10
64QAM
772
4.5234
11
64QAM
873
5.1152.
17. A User Equipment (UE) for transmitting channel state information, comprising:
a receiver configured to receive a reference signal for measuring channel quality from a base station;
a controller configured to measure the channel quality based on the reference signal, and select a channel quality indicator (CQI) index value from a predetermined CQI index table including CQI index values for 256 quadrature amplitude modulation (QAM) modulation, based on the measurement result of the channel quality; and
a transmitter configured to transmit channel state information including the selected CQI index value to the base station,
wherein:
one of the CQI index values for 256QAM modulation is set to a code rate value determined based on a SNR interval calculated using a minimum SNR and a maximum SNR;
the minimum SNR is a required SNR of a CQI index having a maximum code rate value among CQI index values for 64QAM modulation of the CQI index table; and
the maximum SNR is a required SNR of a CQI index having the maximum code rate value among CQI index values for 256QAM modulation of the CQI index table.
18. The User Equipment of claim 17 , wherein the CQI index table includes three CQI index values for QPSK modulation, three CQI index values for 16QAM modulation, five CQI index values for 64QAM modulation, and four CQI index values for 256QAM modulation.
19. The User Equipment of claim 17 , wherein one of the CQI index values for 256QAM modulation is configured to have a code rate value that supports a same transmission efficiency as a maximum transmission efficiency of a CQI index table that excludes CQI index values for 256QAM modulation.
20. The User Equipment of claim 17 , wherein one of the CQI index values for 256QAM modulation is configured to have a same code rate value as the code rate value having a maximum transmission efficiency of a CQI index table that excludes CQI index values for 256QAM modulation.
21. The User Equipment of claim 17 , wherein the CQI index table is configured to include required SNRs between adjacent CQI index values in three CQI index values for QPSK modulation, three CQI index values for 16QAM modulation, and five CQI index values for 64QAM modulation, respectively, to have a same difference within a predetermined error rate, as shown in a table below
CQI index
modulation
code rate x 1024
efficiency
0
out of range
1
QPSK
78
0.1523
2
QPSK
193
0.3770
3
QPSK
449
0.8770
4
16QAM
378
1.4766
5
16QAM
490
1.9141
6
16QAM
616
2.4063
7
64QAM
466
2.7305
8
64QAM
567
3.3223
9
64QAM
666
3.9023
10
64QAM
772
4.5234
11
64QAM
873
5.1152.