Method and device for performing interference coordination in wireless communication system

1. A method for performing interference coordination in a communication system comprising a plurality of user terminals, the method comprising:

determining arrival angles of signals transmitted by the user terminals based on information obtained from the user terminals; and

selecting the user terminals to be served based on the arrival angles of the signals of the user terminals, wherein the step of determining arrival angles of signals transmitted by the user terminals based on the information obtained from the user terminals further comprises:

receiving spread signals from at least one user terminal within a coverage of a base station, wherein the at least one user terminal comprises served terminals served by the base station and interference terminals served by a neighboring base station;

determining whether each of the received spread signals conies from the served terminal or the interference terminal based on a result of de-spreading the received spread signal; and

determining the arrival angle of the signal of each of the at least one user terminal using the received spread signal.

2. The method according to claim 1 , wherein each of the served terminals and the interference terminals spreads a part of data to be transmitted therefrom using one of spreading codes which are orthogonal to one another, and transmits, the spread signal.

3. The method according to claim 1 , wherein each of the served terminals and the interference terminals spreads sounding reference signal generated therefrom using a spreading code, and transmits the spread signal.

4. The method according to claim 3 , wherein the served terminals use the same spreading code, and the sounding reference signals generated by the served terminals are orthogonal to one another,

wherein the spreading code used by the served terminals is orthogonal to the spreading codes used by the interference terminals.

5. A base station in a communication system which comprises a plurality of user terminals, the base station comprising one or more processors configured to:

determine arrival angles of signals transmitted by the user terminals based on information obtained from the user terminals, including

receive spread signals from at least one user terminal within a coverage of the base station, wherein the at least one user terminal comprises served terminals served by the base station and interference terminals served by a neighboring base station;

determine whether each of the received spread signals comes from the served terminal or the interference terminal based on a result of de-spreading the received spread signal, and

determine the arrival angle of the signal of each of the at least one user terminal using the received spread signal; and

select the user terminals to be served based on the arrival angles of the signals of the user terminals.

6. The base station according to claim 5 , wherein the one or more processors are further configured to:

de-spread spread signals from at least one user terminal within a coverage of the base station, wherein the at least one user terminal comprises served terminals served by the base station and interference terminals served by a neighboring base station;

determine whether each of the spread signals comes from the served terminal or the interference terminal based on a result of the de-spreading; and

determine the arrival angle of the signal of each of the at least one user terminal using the spread signal.

7. The base station according to claim 6 , wherein the spread signal is generated by each of the served terminals and the interference terminals by spreading a part of data to be transmitted therefrom using one of spreading codes which are orthogonal to one another.

8. The base station according to claim 6 , wherein the spread signal is generated by each of the served terminals and the interference terminals by spreading sounding reference signal generated therefrom using a spreading code.

9. The base station according to claim 8 , wherein the served terminals use the same spreading code, and the sounding reference signals generated by the served terminals are orthogonal to one another.

10. The method according to claim 9 , wherein the spreading code used by the served terminals is orthogonal to the spreading codes used by the interference terminals.

11. The base station according to claim 6 , wherein the one or more processors are further configured to:

initially restore, in a smart antenna layer, the signal of the served terminal based on the arrival angle of the signal of the served terminal; and

further restore, in a multiple-input multiple-output (MIMO) layer, the signal of the served terminal based on the initially restored signal.

12. The base station according to claim 11 , wherein the one or more processors are further configured to:

determine reception weight vector for the served terminal based on the arrival angle of the signal of the served terminal, and

obtain the initially restored signal of the served terminal using the reception weight vector.

13. The base station according to claim 12 , wherein the one or more processors are further configured to:

determine a covariance matrix of signals transmitted from the interference terminals and noise;

form uplink steering vector for the served terminal by the determined arrival angle of the signal of the served terminal; and

determine the reception weight vector for the served terminal using the determined covariance matrix and the formed uplink steering vector.

14. The base station according to claim 11 , wherein the one or more processors are further configured to:

generate an equivalent MIMO channel in the smart antenna layer; and

perform, in the MIMO layer, noise whitening process on the equivalent MIMO channel, and whiten the initially restored signal.

15. The base station according to claim 11 , wherein the one or more processors are further configured to: restore the signal of the served terminal from the initially restored signal based on zero-forcing algorithm or minimum-mean-square-error algorithm.

16. The base station according to claim 6 , wherein the one or more processors are further configured to:

determine transmission weight vector for the served terminal based on the determined arrival angle of the signal of the served terminal; and

weight a signal for the served terminal by the determined transmission weight vector.

17. The base station according to claim 16 , wherein the one or more processors are further configured to:

determine a covariance matrix of signals transmitted from the base station to the interference terminals;

form downlink steering vector for the served terminal by the determined arrival angle of the signal of the served terminal; and

determine the transmission weight vector for the served terminal using the determined covariance matrix and the formed downlink steering vector.

18. The base station according to claim 16 , wherein the one or more processors are further configured to:

obtain a precoding matrix based on channel large-scale fading coefficient from the served terminal and the transmission weight vector for the served terminal, and

weight the signal for the served terminal by the precoding matrix,

wherein the channel large-scale fading coefficient is estimated by the served terminal based on n pilot transmitted from the base station.