Method for processing degradation of radio link quality in a wireless communication system supporting relays

1. A method for processing degradation of radio link quality in a Relay Node (RN) connected wirelessly to a Base Station (BS) and a User Equipment (UE), the method comprising:

determining, at the RN, quality of a radio link between the BS and the RN;

recovering, at the RN, the radio link between the BS and the RN, when the quality of the radio link between the BS and the RN is decreased to or below a predetermined threshold; and

transmitting, at the RN, to the UE a signaling to control communication on a radio link between the UE and the RN, when the quality of the radio link between the BS and the RN is decreased to or below the predetermined threshold.

2. The method according to claim 1 , wherein when the quality of the radio link between the BS and the RN is decreased to or below the predetermined threshold, a Radio Link Failure (RLF) of the radio link between the BS and the RN is detected.

3. The method according to claim 1 , wherein the signaling to control communication on the radio link between the UE and the RN is a wait message for transmission and reception to and from the UE, a message configuring Discontinuous Transmission/Discontinuous Reception (DTX/DRX) for the UE, or a message commanding the UE to transmit a connection re-establishment request message to a target cell.

4. The method according to claim 1 , wherein the signaling to control communication on the radio link between the UE and the RN is a cell-specific control signaling, a UE-specific control signaling, or a broadcast message.

5. The method according to claim 1 , wherein the recovery of the radio link between the BS and the RN comprises performing handover to a target cell or performing a connection re-establishment procedure.

6. The method according to claim 1 , further comprising transmitting a release message to the UE, when the radio link between the BS and the RN is not recovered in a predetermined time period.

7. The method according to claim 6 , wherein the release message is a cell-specific control signaling, a UE-specific control signaling, or a broadcast message.

8. A Relay Node (RN) for processing degradation of radio link quality, the RN comprising:

a first reception module for receiving a downlink signal from a Base Station (BS);

a first transmission module for transmitting an uplink signal to the BS;

a second reception module for receiving an uplink signal from a User Equipment (UE);

a second transmission module for transmitting a downlink signal to the UE; and

a processor for controlling the RN including the first and second reception modules and the first and second transmission modules,

wherein the processor is configured to:

determine quality of a radio link between the BS and the RN;

recover the radio link between the BS and the RN, when the quality of the radio link between the BS and the RN is decreased to or below a predetermined threshold, and

transmit to the UE through the second transmission module a signaling to control communication on a radio link between the UE and the RN, when the quality of the radio link between the BS and the RN is decreased to or below the predetermined threshold.

9. The RN according to claim 8 , wherein when the quality of the radio link between the BS and the RN is decreased to or below the predetermined threshold, a Radio Link Failure (RLF) of the radio link between the BS and the RN is detected.

10. The RN according to claim 8 , wherein the signaling to control communication on the radio link between the UE and the RN is a wait message for communication to and from the UE, a message configuring Discontinuous Transmission/Discontinuous Reception (DTX/DRX) for the UE, or a message commanding the UE to transmit a connection re-establishment request message to a target cell.

11. The RN according to claim 8 , wherein the signaling to control communication on the radio link between the UE and the RN is a cell-specific control signaling, a UE-specific control signaling, or a broadcast message.

12. The RN according to claim 8 , wherein the processor recovers the radio link between the BS and the RN by performing handover to a target cell or performing a connection re-establishment procedure.

13. The RN according to claim 8 , wherein when the radio link between the BS and the RN is not recovered in a predetermined time period, the processor is further configured to transmit a release message to the UE through the second transmission module.

14. The RN according to claim 13 , wherein the release message is a cell-specific control signaling, a UE-specific control signaling, or a broadcast message.