Method and apparatus for performing extended DRX operation based on uplink indication in wireless communication system

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising:

transmitting a power preference indication message indicating an extended discontinuous reception (eDRX) to a serving cell,

wherein the power preference indication message indicates that the UE has a lower power consumption preference for the eDRX;

receiving a configuration of the eDRX,

wherein a cycle of the eDRX is longer than a cycle of a normal DRX;

receiving system information, which informs that a serving cell does not support the eDRX, from the serving cell;

starting an eDRX timer based on the configuration; and

transmitting an eDRX indication indicating that the eDRX timer is expired, upon expiry of the eDRX timer,

wherein the eDRX indication is transmitted via a physical uplink control channel (PUCCH),

wherein, after transmitting the eDRX indication, all secondary cells (SCells) and all secondary cell group (SCG) cells including a primary SCell (PSCell) are released or deactivated, and

wherein, after transmitting the eDRX indication, all of an on-duration timer, a DRX inactivity timer and a DRX short cycle timer are stopped.

2. The method of claim 1 , further comprising:

starting an on-duration timer for eDRX.

3. The method of claim 1 , further comprising:

triggering a buffer status reporting (BSR) and a scheduling request (SR) towards the serving cell when the UE is in a radio resource control (RRC) connected mode.

4. The method of claim 1 , further comprising:

triggering transmission of a non-access stratum (NAS) service request or an RRC connection request towards the serving cell when the UE is in an RRC idle mode.

5. The method of claim 1 , further comprising:

detecting that an event related to the eDRX, which is that no uplink data is to be transmitted; and

transmitting an uplink message related to the eDRX, which informs that the eDRX is started, to the serving cell.

6. The method of claim 1 , wherein the eDRX indication is transmitted every eDRX cycle.

7. The method of claim 1 , wherein the eDRX indication includes a UE identity.

8. A user equipment (UE) in a wireless communication system, the UE comprising:

a memory;

a transceiver; and

a processor, operatively coupled to the memory and the transceiver,

wherein the processor is configured to:

control the transceiver to transmit a power preference indication message indicating an extended discontinuous reception (eDRX) to a serving cell,

wherein the power preference indication message indicates that the UE has a lower power consumption preference for the eDRX,

control the transceiver to receive a configuration of the eDRX,

wherein a cycle of the eDRX is longer than a cycle of a normal DRX;

control the transceiver to receive system information, which informs that a serving cell does not support the eDRX, from the serving cell;

starting an eDRX timer based on the configuration; and

control the transceiver to transmit an eDRX indication indicating that the eDRX timer is expired, upon expiry of the eDRX timer,

wherein the eDRX indication is transmitted via a physical uplink control channel (PUCCH),

wherein, after transmitting the eDRX indication, all secondary cells (SCells) and all secondary cell group (SCG) cells including a primary SCell (PSCell) are released or deactivated, and

wherein, after transmitting the eDRX indication, all of an on-duration timer, a DRX inactivity timer and a DRX short cycle timer are stopped.