Method for controlling uplink transmissions of a user equipment (UE) in a multi-radio access technology (RAT) environment and apparatus therefor

1. A method for controlling uplink transmissions at a user equipment (UE) in a multi-radio access technology (multi-RAT) environment, the method comprising:

transmitting uplink data for a first RAT and a second RAT to a base station of the first RAT and a base station of the second RAT;

reporting information on UE transmit power for the first RAT and the second RAT according to the transmission of the uplink data, to an entity of the first RAT managing interworking between the first RAT and the second RAT;

receiving a message including information for deactivating an uplink of one of the first and second RATs from the entity of the first RAT, when a sum of the UE transmit power for the first RAT and the UE transmit power for the second RAT exceeds first maximum transmit power; and

selectively deactivating the uplink of the one of the first and second RATs based on the message received from the entity of the first RAT.

2. The method according to claim 1 , further comprising transmitting information on second maximum transmit power allowed to the UE for the second RAT to the entity of the first RAT,

wherein the first maximum transmit power is a maximum value of power for simultaneously transmitting to the first RAT and the second RAT and is determined using the information on the second maximum transmit power.

3. The method according to claim 1 , wherein the selectively deactivating the uplink of the one of the first and second RATs includes sequentially deactivating the uplink of the first RAT and the uplink of the second RAT while downlinks of the first RAT and the second RAT are kept in an active state.

4. The method according to claim 1 , wherein the message received from the entity of the first RAT includes at least one of a deactivation order of the respective uplinks of the first RAT and the second RAT, a deactivation cycle, a deactivation time of a specific RAT within the deactivation cycle, a start time of the deactivation cycle and an offset from the start time.

5. The method according to claim 1 , wherein the reporting the information on the UE transmit power includes transmitting, to the entity of the first RAT, power headroom reporting (PHR) indicating a difference between the UE transmit power and the first maximum transmit power.

6. The method according to claim 1 , further comprising terminating the selective deactivating of the uplink if a predetermined termination condition is satisfied,

wherein the predetermined termination condition comprises at least one of reception of a termination message from the entity of the first RAT, release of a connection with a specific RAT and completion of transmission of last uplink data.

7. The method according to claim 1 , wherein:

the first RAT is a cellular network,

the entity of the first RAT is an eNode B, a mobility management entity (MME) or an interworking management entity (IWME),

the second RAT is a wireless local area network (WLAN), and

the base station of the second RAT is an access point (AP) of the WLAN.

8. A method for controlling an uplink transmission of a user equipment (UE) at an entity managing interworking between multiple radio access technologies (RATs), the method comprising:

receiving information on UE transmit power related to transmission of uplink data to a first RAT and a second RAT; and

transmitting a message including information for deactivating an uplink of one of the first and second RATs, when a sum of the UE transmit power for the first RAT and the UE transmit power for the second RAT exceeds first maximum transmit power,

wherein the uplink of the one of the first and the second RATs is selectively deactivated based on the message.

9. The method according to claim 8 , further comprising:

receiving information on second maximum transmit power allowed to the UE for the second RAT; and

determining the first maximum transmit power using the information on the second maximum transmit power,

wherein the first maximum transmit power is a maximum value of power for simultaneously transmitting to the first RAT and the second RAT.

10. The method according to claim 8 , wherein the uplink of the first RAT and the uplink of the second RAT are sequentially deactivated while downlinks of the first RAT and the second RAT are kept in an active state.

11. The method according to claim 8 , wherein the message includes at least one of a deactivation order of the respective uplinks of the first RAT and the second RAT, a deactivation cycle, a deactivation time of a specific RAT within the deactivation cycle, a start time of the deactivation cycle and an offset from the start time.

12. The method according to claim 8 , wherein the information on the UE transmit power includes power headroom reporting (PHR) indicating a difference between the UE transmit power of and the first maximum transmit power.

13. The method according to claim 8 , wherein:

the first RAT is a cellular network,

the second RAT is a wireless local area network (WLAN), and

the entity is an eNode B, a mobility management entity (MME) or an interworking management entity (IWME) in the cellular network.