Precoding method and apparatus, and precoding control method and apparatus

1. A method of controlling precoding of a terminal in a serving base station, the method comprising:

determining a first codeword that maximizes transmission power in a codebook;

receiving an index of a second codeword that minimizes interference to a neighboring base station from the neighboring base station; and

transmitting an index of the first codeword, the index of the second codeword, and a combination ratio of a precoding matrix corresponding to the index of the first codeword and a precoding matrix corresponding to the index of the second codeword to the terminal.

2. The method of claim 1 , further comprising receiving a sounding signal from the terminal,

wherein determining the first codeword comprises

calculating a channel between the serving base station and the terminal based on the sounding signal, and

determining the first codeword based on the channel.

3. The method of claim 1 , wherein the index of the first codeword is determined by

argmax

i

⁢



H

s

⁢

v

i



2

,

wherein the H S is a channel between the serving base station and the terminal, and the v i is a codeword having index i in the codebook.

4. The method of claim 1 , wherein the index of the second codeword is determined by

argmin

i

⁢



H

I

⁢

v

i



2

,

wherein the H l is a channel between the neighboring base station and the terminal, and the v i is a codeword having index i in the codebook.

5. The method of claim 1 , further comprising:

receiving an interference amount of each terminal measured based on a cell specific sounding signal transmitted from a plurality of terminals from at least one neighboring base station;

selecting a terminal having an interference amount that exceeds a reference value as a terminal for receiving the combination ratio among the plurality of terminals; and

selecting a neighboring base station that has the maximum interference amount with regard to the selected terminal among at least one neighboring base station as a neighboring base station for receiving the index of the second codeword.

6. The method of claim 5 , wherein the inference amount is measured for each sub-band or each logical resource unit.

7. The method of claim 1 , further comprising:

receiving, from a plurality of terminals, identification information of the neighboring base station and a received signal strength difference between the serving base station and the neighboring base station in each terminal; and

selecting a terminal to receive the combination ratio among the plurality of terminals based on the received signal strength difference.

8. A precoding method in a terminal, comprising:

receiving, from a serving base station, an index of a first codeword that maximizes transmission power of a serving base station, an index of a second codeword that minimizes interference to a neighboring base station, and a combination ratio of a first precoding matrix corresponding to the index of the first codeword and a second precoding matrix corresponding to the index of the second codeword; and

generating a transmission precoding matrix by combining the first precoding matrix and the second precoding matrix according to the combination ratio.

9. The method of claim 8 , further comprising transmitting a sounding signal, and

wherein the first codeword is determined by the serving base station based on the sounding signal, and the second codeword is determined by the neighboring base station based on the sounding signal.

10. The method of claim 8 , wherein the index of the first codeword is determined by

argmax

i

⁢



H

s

⁢

v

i



2

,

wherein the H s is a channel between the serving base station and the terminal, and the v i is a codeword having an index i in a codebook.

11. The method of claim 8 , wherein the index of the second codeword is determined by

argmin

i

⁢



H

I

⁢

v

i



2

,

wherein the H l is a channel between the neighboring base station and the terminal, and the v i is a codeword having an index i in a codebook.

12. The method of claim 8 , wherein the transmission precoding matrix is determined by

PCR

·

W

PMI

max

+

(

1

-

PCR

)

·

W

PMI

min



PCR

·

W

PMI

max

+

(

1

-

PCR

)

·

W

PMI

min



,

wherein the W PMI max is the first precoding matrix, the W PMIimin is the second precoding matrix, and the PCR is the combination ratio.

13. The method of claim 8 , further comprising transmitting a cell specific sounding signal so that the serving base station can select the terminal and the neighboring base station.

14. A precoding control apparatus of a serving base station, comprising:

a neighboring base station cooperation unit that receives an index of a first codeword from a neighboring base station;

a precoding controller that determines an index of a second codeword, and a combination ratio of a precoding matrix corresponding to the index of the first codeword and a precoding matrix corresponding to the index of the second codeword; and

a transceiver that transmits the index of the first codeword, the index of the second codeword, and the combination ratio to the terminal,

wherein the second codeword is a codeword that maximizes a norm of each codeword and a channel between the serving base station and the terminal in a codebook, and

the first codeword is a codeword that minimizes a norm of each codeword and a channel between the neighboring base station and the terminal in the codebook.

15. The apparatus of claim 14 , wherein the transceiver receives a sounding signal from the terminal, and

the precoding controller calculates a channel between the serving base station and the terminal based on the sounding signal, and determines the first codeword based on the channel.

16. A precoding apparatus of a terminal, comprising:

a transceiver that receives an index of a first codeword, an index of a second codeword, and a combination ratio of a first precoding matrix corresponding to the index of the first codeword and a second precoding matrix corresponding to the index of the second codeword from a serving base station; and

a precoding unit that generates a transmission precoding matrix by combining the first precoding matrix and the second precoding matrix according to the combination ratio,

wherein the first codeword is a codeword that maximizes a norm of each codeword and a channel between the serving base station and the terminal in a codebook, and

the second codeword is a codeword that minimizes a norm of each codeword and a channel between the neighboring base station and the terminal in the codebook.

17. The apparatus of claim 16 , wherein the transmission precoding matrix is determined by

PCR

·

W

PMI

max

+

(

1

-

PCR

)

·

W

PMI

min



PCR

·

W

PMI

max

+

(

1

-

PCR

)

·

W

PMI

min



,

wherein the W PMImax is the first precoding matrix, the W PMImin is the second precoding matrix, and the PCR is the combination ratio.