Channel status information feedback method and apparatus in wireless communication system with relay station

1. A method for transmitting channel status information at a relay node, the method comprising:

receiving, by the relay node from a base station, a Backhaul downlink signal including a pilot signal;

performing, by the relay node, a channel estimation for a Backhaul downlink channel based upon the pilot signal included in the Backhaul downlink signal;

generating, by the relay node, channel status information based upon the channel estimation,

wherein the channel status information includes at least one of rank information, precoding information, or channel quality information; and

transmitting, by the relay node, the channel status information through a Backhaul uplink subframe,

wherein the Backhaul uplink subframe through which the channel status information is transmitted is decided based upon a subframe index to which a Backhaul downlink subframe is not designated and a Backhaul uplink transmission timing relation,

wherein the channel status information is periodically transmitted from a channel status information periodic transmission starting point, and

wherein the Backhaul uplink transmission timing relation corresponds to at least one of a timing relation between a Backhaul uplink grant and a Backhaul uplink data transmission or a timing relation between the Backhaul uplink data transmission and a Backhaul downlink acknowledgement response.

2. The method of claim 1 , wherein the Backhaul uplink subframe through which the channel status information is transmitted is a subframe out of a set including subframe indexes # 0 , # 1 , # 2 , # 5 , # 6 , and # 7 when the relay node is in an FDD (Frequency Division Duplex) mode, and is a subframe out of a set including subframe indexes # 1 , # 2 , # 3 , # 6 , # 7 , and # 8 when the relay node is in a TDD (Time Division Duplex) mode.

3. The method of claim 2 , further comprising:

receiving, by the relay node from a user equipment, user equipment channel status information via a subframe out of a set including one of subframe indexes # 3 , # 4 , # 8 , and # 9 when the relay node is in an FDD mode, and via a subframe out of a set including one of subframe indexes # 0 , # 4 , # 5 , and # 9 when the relay node is in a TDD mode.

4. The method of claim 1 , wherein the Backhaul uplink subframe through which the channel status information is transmitted is a subframe out of a set including subframe indexes # 2 , # 3 , # 4 , # 7 , # 8 , and # 9 when the relay node is in an FDD mode, and is a subframe out of a set including subframe indexes # 0 , # 3 , # 4 , # 5 , # 8 , and # 9 when the relay node is in a TDD mode.

5. The method of claim 4 , further comprising:

receiving, by the relay node from a user equipment, user equipment channel status information via a subframe out of a set including one of subframe indexes # 0 , # 1 , # 5 , and # 6 when the relay node is in an FDD mode, and via a subframe out of a set including one of subframe indexes # 1 , # 2 , # 6 , and # 7 when the relay node is in a TDD mode.

6. The method of claim 1 , wherein the subframe index to which the Backhaul downlink subframe is not designated corresponds to at least one of subframe indexes # 0 , # 4 , # 5 , and # 9 when the relay node is in an FDD mode, and corresponds to at least one of subframe indexes # 0 , # 1 , # 5 , and # 6 when the relay node is in a TDD mode.

7. The method of claim 1 ,

wherein the Backhaul uplink transmission timing relation includes the timing relation between the Backhaul uplink grant and the Backhaul uplink data transmission and the timing relation between the Backhaul uplink data transmission and the Backhaul downlink acknowledgement response, and

wherein the Backhaul uplink subframe through which the channel status information is transmitted is a subframe out of a set including subframe indexes # 2 and # 7 when the relay node is in an FDD mode, and is a subframe out of a set including subframe indexes # 3 and # 8 when the relay node is in a TDD mode.

8. The method of claim 1 , wherein the Backhaul uplink subframe through which the channel status information is transmitted is the channel status information periodic transmission starting point.

9. The method of claim 1 , wherein information on the Backhaul uplink subframe through which the channel status information is transmitted and information on a period of the periodically transmitted channel status information are notified through higher-layer signaling or L1/L2 control signaling from the base station.

10. The method of claim 1 , wherein a periodicity for the channel status information transmission is a lowest common multiple between a periodicity of Backhaul uplink subframes transmitted by the relay node and a periodicity of the periodically transmitted channel status information.

11. The method of claim 1 , a periodicity for the channel status information transmission is a multiple of N (N≧1) of 5 subframes, where N is an integer.

12. A relay node configured to transmit channel status information and comprising:

a receiving circuit configured to receive a Backhaul downlink signal from a base station and to receive an Access uplink signal from a user equipment;

a transmitting circuit configured to transmit a Backhaul uplink signal to the base station and to transmit an Access downlink signal to the user equipment; and

a processor configured to control the receiving circuit and the transmitting circuit,

wherein the Backhaul downlink signal includes a pilot signal,

wherein the processor is configured to:

perform a channel estimation for a Backhaul downlink channel based upon the pilot signal included in the Backhaul downlink signal,

generate channel status information based upon the channel estimation,

wherein the channel status information includes at least one of rank information, precoding information, or channel quality information, and

transmit the channel status information through a Backhaul uplink subframe through the transmitting circuit, and

wherein a Backhaul uplink subframe through which the channel status information is transmitted is decided based upon a timing relation between a subframe index to which a Backhaul downlink subframe is not designated and Backhaul uplink transmission,

wherein the channel status information is periodically transmitted from a channel status information periodic transmission starting point, and

wherein the Backhaul uplink transmission timing relation corresponds to at least one of a timing relation between a Backhaul uplink grant and a Backhaul uplink data transmission or a timing relation between the Backhaul uplink data transmission and a Backhaul downlink acknowledgement response.