Method and apparatus for efficient feedback in a wireless communication system supporting multiple antenna

1. A method for transmitting channel status information (CSI) of downlink transmission via uplink in a wireless communication system, the method comprising:

transmitting a rank indicator (RI) at a first subframe; and

transmitting a first precoding matrix indicator (PMI), a second PMI, and a wideband (WB) channel quality indicator (CQI) at a second subframe,

wherein a user equipment (UE) preferred precoding matrix is indicated by a combination of the first PMI and the second PMI, and

a subsampled codebook for each precoding codebook of ranks from Rank-1 to Rank-4 is applied to the first PMI and the second PMI, and a sum of the first PMI and the second PMI for each of Rank-1 to Rank-4 is comprised of 4 bits.

2. The method according to claim 1 , wherein, in association with each of the Rank-1 and the Rank-2, the first PMI is comprised of 3 bits in the subsampled codebook, and the second PMI is comprised of 1 bit.

3. The method according to claim 1 , wherein, in association with each of the Rank-3 and the Rank-4, the first PMI is comprised of 1 bit in the subsampled codebook, and the second PMI is comprised of 3 bits.

4. The method according to claim 1 , wherein:

the RI is transmitted over a physical uplink control channel (PUCCH) of the first subframe, and

the first PMI, the second PMI, and the CQI are transmitted over a PUCCH of the second subframe.

5. The method according to claim 1 , wherein the RI, the first PMI, the second PMI, and the CQI are contained in channel status information (CSI) of downlink 8 transmission (Tx) antennas.

6. The method according to claim 1 , wherein:

the RI is transmitted according to a first report cycle, and

the first PMI, the second PMI, and the CQI are transmitted according to a second report cycle.

7. The method according to claim 2 , wherein the precoding codebook for the Rank-1 is represented by the following table:

TABLE

i 2

i 1

 0

 1

 2

 3

0-15

W 2i 1 ,0 (1)

W 2i 1 ,1 (1)

W 2i 1 ,2 (1)

W 2i 1 ,3 (1)

i 2

i 1

 4

 5

 6

 7

0-15

W 2i 1 +1,0 (1)

W 2i 1 +1,1 (1)

W 2i 1 +1,2 (1)

W 2i 1 +1,3 (1)

i 2

i 1

 8

 9

10

11

0-15

W 2i 1 +2,0 (1)

W 2i 1 +2,1 (1)

W 2i 1 +2,2 (1)

W 2i 1 +2,3 (1)

i 2

i 1

12

13

14

15

0-15

W 2i 1 +3,0 (1)

W 2i 1 +3,1 (1)

W 2i 1 +3,2 (1)

W 2i 1 +3,3 (1)

where

⁢

⁢

W

m

,

n

(

1

)

=

1

8

⁡

[

ν

m

φ

n

⁢

ν

m

]

where φ n is denoted by φ n =e jπn/2 and ν m is denoted by ν m =[1 e j2πm/32 e j4πm/32 e j6πm/32 ] T , and

in case of the Rank-1, the first PMI is set to any one of 0, 2, 4, 6, 8, 10, 12 and 14, and the second PMI is set to any one of 0 and 2.

8. The method according to claim 2 , wherein the precoding codebook for the Rank-2 is represented by the following table:

TABLE

i 2

i 1

 0

 1

 2

 3

0-15

W 2i 1 ,2i 1 ,0 (2)

W 2i 1 ,2i 1 ,1 (2)

W 2i 1 +1,2i 1 +1,0 (2)

W 2i 1 +1,2i 1 +1,1 (2)

i 2

i 1

 4

 5

 6

 7

0-15

W 2i 1 +2,2i 1 +2,0 (2)

W 2i 1 +2,2i 1 +2,1 (2)

W 2i 1 +3,2i 1 +3,0 (2)

W 2i 1 +3,2i 1 +3,1 (2)

i 2

i 1

 8

 9

 10

 11

0-15

W 2i 1 ,2i 1 +1,0 (2)

W 2i 1 ,2i 1 +1,1 (2)

W 2i 1 +1,2i 1 +2,0 (2)

W 2i 1 +1,2i 1 +2,1 (2)

i 2

i 1

12

13

14

15

0-15

W 2i 1 ,2i 1 +3,0 (2)

W 2i 1 ,2i 1 +3,1 (2)

W 2i 1 +1,2i 1 +3,0 (2)

W 2i 1 +1,2i 1 +3,1 (2)

where

⁢

⁢

W

m

,

m

′

,

n

(

2

)

=

1

4

⁡

[

ν

m

ν

m

′

φ

n

⁢

ν

m

-

φ

n

⁢

ν

m

′

]

where φ n is denoted by φ n =e jπn/2 and ν m is denoted by ν m =[1 e j2πm/32 e j4πm/32 e j6πm/32 ] T , and

in case of the Rank-2, the first PMI is set to any one of 0, 2, 4, 6, 8, 10, 12 and 14, and the second PMI is set to any one of 0 and 1.

9. The method according to claim 3 , wherein the precoding codebook for the Rank-3 is represented by the following table:

TABLE

i 2

i 1

 0

 1

0-3

W 8i 1 ,8i 1 ,8i 1 +8 (3)

W 8i 1 +8,8i 1 ,8i 1 +8 (3)

i 2

i 1

 2

 3

0-3

{tilde over (W)} 8i 1 ,8i 1 +8,8i 1 +8 (3)

{tilde over (W)} 8i 1 +8,8i 1 ,8i 1 (3)

i 2

i 1

 4

 5

0-3

W 8i 1 +2,8i 1 +2,4i 1 +10 (3)

W 8i 1 +10,8i 1 +2,8i 1 +10 (3)

i 2

i 1

 6

 7

0-3

{tilde over (W)} 8i 1 +2,8i 1 +10,8i 1 +10 (3)

{tilde over (W)} 8i 1 +10,8i 1 +2,8i 1 +2 (3)

i 2

i 1

 8

 9

0-3

W 8i 1 +4,8i 1 +4,8i 1 +12 (3)

W 8i 1 +12,8i 1 +4,8i 1 +12 (3)

i 2

i 1

10

11

0-3

{tilde over (W)} 8i 1 +4,8i 1 +12,8i 1 +12 (3)

{tilde over (W)} 8i 1 +12,8i 1 +4,8i 1 +4 (3)

i 2

i 1

12

13

0-3

W 8i 1 +6,8i 1 +6,8i 1 +14 (3)

W 8i 1 +14,8i 1 +6,8i 1 +14 (3)

i 2

i 1

14

15

0-3

{tilde over (W)} 8i 1 +6,8i 1 +14,8i 1 +14 (3)

{tilde over (W)} 8i 1 +14,8i 1 +6,8i 1 +6 (3)

where

⁢

⁢

W

m

,

m

′

,

m

″

(

3

)

=

1

24

⁡

[

ν

m

ν

m

′

ν

m

″

ν

m

-

ν

m

′

-

ν

m

″

]

,

W

~

m

,

m

′

,

m

″

(

3

)

=

1

24

⁡

[

ν

m

ν

m

′

ν

m

″

ν

m

ν

m

′

-

ν

m

″

]

where φ n is denoted by φ n =e jπn/2 and ν m is denoted by ν m =[1 e j2πm/32 e j4πm/32 e j6πm/32 ] T , and

in case of the Rank-3, the first PMI is set to any one of 0 and 2, and the second PMI is set to any one of 0, 1, 2, 3, 8, 9, 10 and 11.

10. The method according to claim 3 , wherein the precoding codebook for the Rank-4 is represented by the following table:

TABLE

i 2

i 1

0

1

2

3

0-3

W 8i 1 ,8i 1 +8,0 (4)

W 8i 1 ,8i 1 +8,1 (4)

W 8i 1 +2,8i 1 +10,0 (4)

W 8i 1 +2,8i 1 +10,1 (4)

i 2

i 1

4

5

6

7

0-3

W 8i 1 +4,8i 1 +12,0 (4)

W 8i 1 +4,8i 1 +12,1 (4)

W 8i 1 +6,8i 1 +14,0 (4)

W 8i 1 +6,8i 1 +14,1 (4)

where

⁢

⁢

W

m

,

m

′

,

n

(

4

)

=

1

32

⁡

[

ν

m

ν

m

′

ν

m

ν

m

′

φ

n

⁢

ν

m

φ

n

⁢

ν

m

′

-

φ

n

⁢

ν

m

-

φ

n

⁢

ν

m

′

]

where φ n is denoted by φ n =e jπn/2 and ν m is denoted by ν m =[1 e j2πm/32 e j4πm/32 e j6πm/32 ] T , and

in case of the Rank-4, the first PMI is set to any one of 0 and 2, and the second PMI is set to any one of 0, 1, 2, 3, 4, 5, 6 and 7.

11. A method for receiving channel status information (CSI) of downlink transmission via uplink in a wireless communication system, the method comprising:

receiving a rank indicator (RI) at a first subframe; and

receiving a first precoding matrix indicator (PMI), a second PMI, and a wideband (WB) channel quality indicator (CQI) at a second subframe,

wherein a user equipment (UE) preferred precoding matrix is indicated by a combination of the first PMI and the second PMI, and

a subsampled codebook for each precoding codebook of ranks from Rank-1 to Rank-4 is applied to the first PMI and the second PMI, and a sum of the first PMI and the second PMI for each of Rank-1 to Rank-4 is comprised of 4 bits.

12. The method according to claim 11 , wherein, in association with each of the Rank-1 and the Rank-2, the first PMI is comprised of 3 bits in the subsampled codebook, and the second PMI is comprised of 1 bit.

13. The method according to claim 11 , wherein, in association with each of the Rank-3 and the Rank-4, the first PMI is comprised of 1 bit in the subsampled codebook, and the second PMI is comprised of 3 bits.

14. The method according to claim 11 , wherein:

the RI is received over a physical uplink control channel (PUCCH) of the first subframe, and

the first PMI, the second PMI, and the CQI are received over a PUCCH of the second subframe.

15. The method according to claim 11 , wherein the RI, the first PMI, the second PMI, and the CQI are contained in channel status information (CSI) of downlink 8 transmission (Tx) antennas.

16. The method according to claim 11 , wherein:

the RI is received according to a first report cycle, and

the first PMI, the second PMI, and the CQI are received according to a second report cycle.

17. The method according to claim 12 , wherein the precoding codebook for the Rank-1 is represented by the following table:

TABLE

i 2

i 1

 0

 1

 2

 3

0-15

W 2i 1 ,0 (1)

W 2i 1 ,1 (1)

W 2i 1 ,2 (1)

W 2i 1 ,3 (1)

i 2

i 1

 4

 5

 6

 7

0-15

W 2i 1 +1,0 (1)

W 2i 1 +1,1 (1)

W 2i 1 +1,2 (1)

W 2i 1 +1,3 (1)

i 2

i 1

 8

 9

10

11

0-15

W 2i 1 +2,0 (1)

W 2i 1 +2,1 (1)

W 2i 1 +2,2 (1)

W 2i 1 +2,3 (1)

i 2

i 1

12

13

14

15

0-15

W 2i 1 +3,0 (1)

W 2i 1 +3,1 (1)

W 2i 1 +3,2 (1)

W 2i 1 +3,3 (1)

where

⁢

⁢

W

m

,

n

(

1

)

=

1

8

⁡

[

ν

m

φ

n

⁢

ν

m

]

where φ n is denoted by φ n =e jπn/2 and ν m is denoted by ν m =[1 e j2πm/32 e j4πm/32 e j6πm/32 ] T , and

in case of the Rank-1, the first PMI is set to any one of 0, 2, 4, 6, 8, 10, 12 and 14, and the second PMI is set to any one of 0 and 2.

18. The method according to claim 12 , wherein the precoding codebook for the Rank-2 is represented by the following table:

TABLE

i 2

i 1

 0

 1

 2

 3

0-15

W 2i 1 ,2i 1 ,0 (2)

W 2i 1 ,2i 1 ,1 (2)

W 2i 1 +1,2i 1 +1,0 (2)

W 2i 1 +1,2i 1 +1,1 (2)

i 2

i 1

 4

 5

 6

 7

0-15

W 2i 1 +2,2i 1 +2,0 (2)

W 2i 1 +2,2i 1 +2,1 (2)

W 2i 1 +3,2i 1 +3,0 (2)

W 2i 1 +3,2i 1 +3,1 (2)

i 2

i 1

 8

 9

 10

 11

0-15

W 2i 1 ,2i 1 +1,0 (2)

W 2i 1 ,2i 1 +1,1 (2)

W 2i 1 +1,2i 1 +2,0 (2)

W 2i 1 +1,2i 1 +2,1 (2)

i 2

i 1

12

13

14

15

0-15

W 2i 1 ,2i 1 +3,0 (2)

W 2i 1 ,2i 1 +3,1 (2)

W 2i 1 +1,2i 1 +3,0 (2)

W 2i 1 +1,2i 1 +3,1 (2)

where

⁢

⁢

W

m

,

m

′

,

n

(

2

)

=

1

4

⁡

[

ν

m

ν

m

′

φ

n

⁢

ν

m

-

φ

n

⁢

ν

m

′

]

where φ n is denoted by φ n =e jπn/2 and ν m is denoted by ν m =[1 e j2πm/32 e j4πm/32 e j6πm/32 ] T , and

in case of the Rank-2, the first PMI is set to any one of 0, 2, 4, 6, 8, 10, 12 and 14, and the second PMI is set to any one of 0 and 1.

19. The method according to claim 13 , wherein the precoding codebook for the Rank-3 is represented by the following table:

TABLE

i 2

i 1

 0

 1

0-3

W 8i 1 ,8i 1 ,8i 1 +8 (3)

W 8i 1 +8,8i 1 ,8i 1 +8 (3)

i 2

i 1

 2

 3

0-3

{tilde over (W)} 8i 1 ,8i 1 +8,8i 1 +8 (3)

{tilde over (W)} 8i 1 +8,8i 1 ,8i 1 (3)

i 2

i 1

 4

 5

0-3

W 8i 1 +2,8i 1 +2,4i 1 +10 (3)

W 8i 1 +10,8i 1 +2,8i 1 +10 (3)

i 2

i 1

 6

 7

0-3

{tilde over (W)} 8i 1 +2,8i 1 +10,8i 1 +10 (3)

{tilde over (W)} 8i 1 +10,8i 1 +2,8i 1 +2 (3)

i 2

i 1

 8

 9

0-3

W 8i 1 +4,8i 1 +4,8i 1 +12 (3)

W 8i 1 +12,8i 1 +4,8i 1 +12 (3)

i 2

i 1

10

11

0-3

{tilde over (W)} 8i 1 +4,8i 1 +12,8i 1 +12 (3)

{tilde over (W)} 8i 1 +12,8i 1 +4,8i 1 +4 (3)

i 2

i 1

12

13

0-3

W 8i 1 +6,8i 1 +6,8i 1 +14 (3)

W 8i 1 +14,8i 1 +6,8i 1 +14 (3)

i 2

i 1

14

15

0-3

{tilde over (W)} 8i 1 +6,8i 1 +14,8i 1 +14 (3)

{tilde over (W)} 8i 1 +14,8i 1 +6,8i 1 +6 (3)

where

⁢

⁢

W

m

,

m

′

,

m

″

(

3

)

=

1

24

⁡

[

ν

m

ν

m

′

ν

m

″

ν

m

-

ν

m

′

-

ν

m

″

]

,

W

~

m

,

m

′

,

m

″

(

3

)

=

1

24

⁡

[

ν

m

ν

m

′

ν

m

″

ν

m

ν

m

′

-

ν

m

″

]

where φ n is denoted by φ n =e jπn/2 and ν m is denoted by ν m =[1 e j2πm/32 e j4πm/32 e j6πm/32 ] T , and

in case of the Rank-3, the first PMI is set to any one of 0 and 2, and the second PMI is set to any one of 0, 1, 2, 3, 8, 9, 10 and 11.

20. The method according to claim 13 , wherein the precoding codebook for the Rank-4 is represented by the following table:

TABLE

i 2

i 1

0

1

2

3

0-3

W 8i 1 ,8i 1 +8,0 (4)

W 8i 1 ,8i 1 +8,1 (4)

W 8i 1 +2,8i 1 +10,0 (4)

W 8i 1 +2,8i 1 +10,1 (4)

i 2

i 1

4

5

6

7

0-3

W 8i 1 +4,8i 1 +12,0 (4)

W 8i 1 +4,8i 1 +12,1 (4)

W 8i 1 +6,8i 1 +14,0 (4)

W 8i 1 +6,8i 1 +14,1 (4)

where

⁢

⁢

W

m

,

m

′

,

n

(

4

)

=

1

32

⁡

[

ν

m

ν

m

′

ν

m

ν

m

′

φ

n

⁢

ν

m

φ

n

⁢

ν

m

′

-

φ

n

⁢

ν

m

-

φ

n

⁢

ν

m

′

]

where φ n is denoted by φ n =e jπn/2 and ν m is denoted by ν m =[1 e j2πm/32 e j4πm/32 e j6πm/32 ] T , and

in case of the Rank-4, the first PMI is set to any one of 0 and 2, and the second PMI is set to any one of 0, 1, 2, 3, 4, 5, 6 and 7.

21. A user equipment (UE) for transmitting channel status information (CSI) of downlink transmission via uplink in a wireless communication system comprising:

a reception module for receiving a downlink signal from a base station (BS);

a transmission module for transmitting an uplink signal to the base station (BS); and

a processor for controlling the user equipment (UE) including the reception module and the transmission module,

wherein the processor, through the transmission module, transmits a rank indicator (RI) at a first subframe, and transmits a first precoding matrix indicator (PMI), a second PMI, and a wideband (WB) channel quality indicator (CQI) at a second subframe,

a UE preferred precoding matrix is indicated by a combination of the first PMI and the second PMI, and

a subsampled codebook for each precoding codebook of ranks from Rank-1 to Rank-4 is applied to the first PMI and the second PMI, and a sum of the first PMI and the second PMI for each of Rank-1 to Rank-4 is comprised of 4 bits.

22. A base station (BS) for receiving channel status information (CSI) of downlink transmission via uplink in a wireless communication system comprising:

a reception module for receiving an uplink signal from a user equipment (UE);

a transmission module for transmitting a downlink signal to the user equipment (UE); and

a processor for controlling the base station (BS) including the reception module and the transmission module,

wherein the processor, through the reception module, receives a rank indicator (RI) at a first subframe, and receives a first precoding matrix indicator (PMI), a second PMI, and a wideband (WB) channel quality indicator (CQI) at a second subframe,

a UE preferred precoding matrix is indicated by a combination of the first PMI and the second PMI, and a subsampled codebook for each precoding codebook of ranks from Rank-1 to Rank-4 is applied to the first PMI and the second PMI, and a sum of the first PMI and the second PMI for each of Rank-1 to Rank-4 is comprised of 4 bits.