Method and apparatus for maintaining MBMS MDT configuration in wireless communication system

1. A method for maintaining, by a user equipment (UE), a multimedia broadcast multicast service (MBMS) minimization of drive test (MDT) configuration in a wireless communication system, the method comprising:

receiving, by the UE, a first MBMS-MDT configuration via first system information from a first cell;

starting, by the UE, a MBMS-MDT based on the first MBMS-MDT configuration in the first cell;

performing, by the UE, handover procedure from the first cell to a second cell;

receiving, by the UE, a second MBMS-MDT configuration via second system information from the second cell;

checking, by the UE, whether the first MBMS-MDT configuration is equivalent to the second MBMS-MDT configuration, by comparing value tags assigned to the first MBMS-MDT configuration and the second MBMS-MDT configuration, respectively; and

maintaining, by the UE, the ongoing MBMS-MDT based on the first MBMS-MDT configuration while the UE is located in the second cell, when the first MBMS-MDT configuration is equivalent to the second MBMS-MDT configuration.

2. The method of claim 1 , wherein the MBMS-MDT comprises performing MBMS measurements, logging measurement results and reporting logged results.

3. The method of claim 2 , wherein the MBMS measurements includes at least one of a MBSFN reference signal received power (RSRP) per MBSFN area, a MBSFN reference signal received quality (RSRQ) per MBSFN area, multicast channel (MCH) block error rate (BLER) per modulation and coding scheme (MCS), per MCH, and per MBSFN area, or amount of received radio link control (RLC) service data units (SDUs) for a certain period of time.

4. The method of claim 1 , wherein the first MBMS-MDT configuration includes at least one of a logging duration, a logging interval, a MBMS measurement duration, a MBMS measurement interval, a MBSNF area identity list, or a timer T330m.

5. The method of claim 4 , wherein the timer T330m starts upon receiving the first MBMS-MDT configuration.

6. The method of claim 4 , wherein the timer T330m stops upon log volume exceeding capability of a memory of the UE, or upon initiating release of a MBMS-MDT configuration procedure.

7. The method of claim 1 , wherein the first MBMS-MDT configuration is received via an existing system information block (SIB) or a newly defined SIB for MBMS-MDT, in the first system information.

8. The method of claim 1 , further comprising performing, by the UE, MBMS-MDT based on the second MBMS-MDT configuration, if the second system information includes the second MBMS-MDT configuration which is different from the first MBMS-MDT configuration.

9. A user equipment (UE) configured to maintain a multimedia broadcast multicast service (MBMS) minimization of drive test (MDT) configuration in a wireless communication system, the UE comprising:

a radio frequency (RF) unit configured to transmit or receive a radio signal; and

a processor coupled to the RF unit, and configured to:

receive a first MBMS-MDT configuration via first system information from a first cell;

start a MBMS-MDT based on the first MBMS-MDT configuration in the first cell;

perform handover procedure from the first cell to a second cell;

receive a second MBMS-MDT configuration via second system information from the second cell;

check whether the first MBMS-MDT configuration is equivalent to the second MBMS-MDT configuration, by comparing value tags assigned to the first MBMS-MDT configuration and the second MBMS-MDT configuration, respectively; and

maintain the ongoing MBMS-MDT based on the first MBMS-MDT configuration while the UE is located in the second cell, when the first MBMS-MDT configuration is equivalent to the second MBMS-MDT configuration.

10. The UE of claim 9 , wherein the MBMS-MDT comprises performing MBMS measurements, logging measurement results and reporting logged results.

11. The UE of claim 10 , wherein the MBMS measurements includes at least one of a MBSFN reference signal received power (RSRP) per MBSFN area, a MBSFN reference signal received quality (RSRQ) per MBSFN area, multicast channel (MCH) block error rate (BLER) per modulation and coding scheme (MCS), per MCH, and per MBSFN area, or amount of received radio link control (RLC) service data units (SDUs) for a certain period of time.