Method for handling an unknown MAC PDU and device therefor

1. A method for a User Equipment (UE) operating in a wireless communication system, the method comprising:

receiving a Medium Access Control (MAC) Protocol Data Unit (PDU) including a Logical Channel Identifier (LCID);

discarding a subheader field including the LCID and a MAC Service Data Unit (SDU) related to the LCID in the received MAC PDU when the LCID is an identifier for a logical channel released by the UE; and

processing remaining parts of the MAC PDU, other than the subheader field and the MAC SDU discarded from the MAC PDU,

wherein the LCID is stored during a specific time duration after the logical channel is released, and

wherein the specific time duration is configured based on a timer or pre-defined subframes.

2. The method according to claim 1 , wherein the MAC PDU is received through a dedicated resource.

3. The method according to claim 2 , wherein the MAC PDU is received through a dedicated resource, when the MAC PDU is received for a UE's Cell-Radio Network Temporary Identifier (C-RNTI), Semi-Persistent Scheduling C-RNTI, or by a configured downlink assignment.

4. The method according to claim 1 , wherein a value of the LCID is one of a plurality of values, each corresponding to one of a plurality of logical channels.

5. The method according to claim 4 , wherein the value of the LCID is one of 00001-01010.

6. The method according to claim 1 , wherein the logical channel is released by a Master node, when the UE is connected with the Master node and a Secondary node-simultaneously, and the MAC PDU including the LCID identifying the released logical channel is received from the Secondary node.

7. The method according to claim 6 , wherein when the MAC PDU is received from the Master node, the UE discards the MAC PDU.

8. A User Equipment (UE) operating in a wireless communication system, the UE comprising:

a transceiver; and

a processor, operatively coupled to the transceiver,

wherein the processor is configured to:

control the transceiver to receive a Medium Access Control (MAC) Protocol Data Unit (PDU) including a Logical Channel Identifier (LCID),

discard a subheader field including the LCID and a MAC Service Data Unit (SDU) related to the LCID in the received MAC PDU when the LCID is an identifier for a logical channel released by the UE, and

process remaining parts of the MAC PDU, other than the subheader field and the MAC SDU discarded from the MAC PDU,

wherein the LCID is stored during a specific time duration after the corresponding logical channel is released, and

wherein the specific time duration is configured based on a timer or pre-defined subframes.

9. The UE according to claim 8 , wherein the MAC PDU is received through a dedicated resource.

10. The UE according to claim 9 , wherein the MAC PDU is received through a dedicated resource, when the MAC PDU is received for a UE's Cell-Radio Network Temporary Identifier, Semi-Persistent Scheduling C-RNTI, or by a configured downlink assignment.

11. The UE according to claim 8 , wherein a value of the LCID is one of a plurality of values, each corresponding to one of a plurality of logical channels.

12. The UE according to claim 11 , wherein the value of the LCID is one of 00001-01010.

13. The UE according to claim 8 , wherein the logical channel is released by a Master node, when the UE is connected with the Master node and a Secondary node simultaneously, and the MAC PDU including the LCID identifying the released logical channel is received from the Secondary node.

14. The UE according to claim 13 , wherein when the MAC PDU is received from the Master node, the UE discards the MAC PDU.