Apparatus and method for cooperative relaying based on beamforming in a mobile communication system

1. A method of a relaying a signal based on beamforming by a relay station in a mobile communication system, the method comprising:

decoding a signal received from a transmitting terminal;

determining whether there is an error in the decoded signal;

acquiring a beamforming weight corresponding to decoding error information, if the there is an error in the decoded signal;

applying the beamforming weight to the signal received from the transmitting terminal; and

transmitting, to a receiving terminal, the signal to which the beamforming weight is applied.

2. The method of claim 1 , wherein acquiring the beamforming weight comprises:

transmitting the decoding error information to another relay station or the receiving terminal; and

receiving the beamforming weight from the another relay station or the receiving terminal.

3. The method of claim 1 , wherein acquiring the beamforming weight comprises:

receiving decoding error power values and channel information about the receiving terminal from a plurality of other relay stations;

acquiring a decoding error power value of the relay station and channel information about the receiving terminal;

using the decoding error power values and the channel information to determine a beamforming weight for each of the relay stations; and

transmitting the determined beamforming weights to each corresponding relay station.

4. The method of claim 3 , wherein the beamforming weight for each of the relay stations has a value for maximizing a Signal to Interference and Noise Ratio (SINR) of a signal received by the receiving terminal.

5. The method of claim 1 , further comprising applying a beamforming weight based on channel information of the receiving terminal, to the signal received from the transmitting terminal, if there is no error in the decoded signal.

6. A method of determining beamforming weights by a receiving terminal in a mobile communication system, the method comprising:

receiving decoding error information from a plurality of relay stations;

determining beamforming weights for each of the plurality of relay stations by using the decoding error information; and

transmitting the determined beamforming weights to each of the plurality of relay stations.

7. The method of claim 6 , wherein determining the beamforming weight comprises:

acquiring channel information about each of the plurality of relay stations; and

determining the beamforming weights for each of the plurality of relay stations by using the channel information and decoding error power values received from the plurality of relay stations.

8. The method of claim 6 , wherein the beamforming weights for each of the plurality of relay stations have a value for maximizing a Signal to Interference and Noise Ratio (SINR) of a signal received by the receiving terminal.

9. The method of claim 6 , further comprising;

determining at least one of interference and noise powers of a received signal by using the received decoding error information and the beamforming weight;

receiving a signal with the beamforming weights from the plurality of relay stations; and

decoding the received signal by using at least one of the determined interference and noise powers.

10. A relay station for relaying a signal based on beamforming in a mobile communication system, the apparatus comprising:

a receiving unit for receiving signal from a transmitting terminal;

a decoding error checking unit for checking whether a decoding error occurs in a signal received from a transmitting terminal;

a decoding error estimating unit for estimating decoding error information, if the decoding error occurs;

a weight applying unit for acquiring a beamforming weight corresponding to the estimated decoding error and applying the beamforming weight to the signal received from the transmitting terminal; and

a transmitting unit for transmitting, to a receiving terminal, the signal to which the beamforming weight is applied.

11. The apparatus of claim 10 , wherein the transmitting unit transmits the decoding error information to another relay station or the receiving terminal; and

wherein the receiving unit receives the beamforming weight from the another relay station or the receiving terminal.

12. The apparatus of claim 10 , further comprising:

a receiving unit for receiving decoding error power values and channel information about the receiving terminal from a plurality of other relay stations;

a weight determining unit for acquiring the decoding error power value of the relay station and channel information about the receiving terminal and using the decoding error power values and the channel information to determine beamforming weights for each of the plurality of other relay stations; and

a transmitting unit for transmitting the determined beamforming weights to the relay stations.

13. The apparatus of claim 12 , wherein the beamforming weights for each of the plurality of other relay stations have a value for maximizing a Signal to Interference and Noise Ratio (SINR) of a signal received by the receiving terminal.

14. The apparatus of claim 10 , wherein the weight applying unit applies a beamforming weight, which is based on channel information of the receiving terminal, to the signal received from the transmitting terminal, if the decoding error does not occur.

15. A receiving terminal apparatus determining beamforming weights for relay stations in a mobile communication system, the apparatus comprising:

a receiving unit for receiving decoding error information from a plurality of relay stations;

a weight determining unit for determining beamforming weights for each of the plurality of relay stations by using the received decoding error information; and

a transmitting unit for transmitting the determined beamforming weights to each of the plurality of relay stations.

16. The apparatus of claim 15 , wherein the weight determining unit determines the beamforming weights for each of the plurality of relay stations by using channel information about each of the plurality of relay stations and decoding error power values received from the plurality of relay stations.

17. The apparatus of claim 15 , wherein the beamforming weights for each of the plurality of relay stations have a value for maximizing a Signal to Interference and Noise Ratio (SINR) of a signal received by the receiving terminal.

18. The apparatus of claim 15 , wherein the receiving unit receives a signal with the beamforming weights from the relay stations, and

wherein the receiving unit receives comprises:

a interference and noise power determining unit for determining at least one of interference and noise powers of a received signal by using the received decoding error information and the beamforming weights; and

a decoding unit for decoding the received signal by using at least one of the determined interference and noise powers.