Method and apparatus of handling discontinuous reception (DRX) timer for multicast data reception in a wireless communication system
A method and apparatus are disclosed. In an example from the perspective of a User Equipment (UE), the UE receives and/or detects a multicast transmission of downlink data on a configured downlink multicast resource, wherein the multicast transmission is associated with a Hybrid Automatic Repeat Request (HARQ) process. The UE starts a multicast HARQ Round Trip Time (RTT) timer associated with the HARQ process. The UE determines whether to start a unicast HARQ RTT timer associated with the HARQ process based on whether the UE is configured with a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI).
1. A method of a User Equipment (UE), comprising:
being configured with a Group Configured Scheduling RNTI (G-CS-RNTI) by a base station, wherein the G-CS-RNTI is used for Semi-Persistent Scheduling (SPS) activation associated with a multicast configured downlink resource;
at least one of receiving or detecting a multicast transmission of downlink data on the multicast configured downlink resource after SPS activation, wherein the multicast transmission is associated with a Hybrid Automatic Repeat Request (HARQ) process;
starting a multicast HARQ Round Trip Time (RTT) timer associated with the HARQ process; and
determining whether to start a unicast HARQ RTT timer associated with the HARQ process based on whether the UE is configured with a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI).
2. The method of claim 1 , comprising:
starting the unicast HARQ RTT timer based on the UE being configured with the CS-RNTI.
3. The method of claim 2 , comprising:
starting a unicast Discontinuous Reception (DRX) retransmission timer associated with the HARQ process in response to expiry of the unicast HARQ RTT timer.
4. The method of claim 3 , comprising:
monitoring Physical Downlink Control Channel (PDCCH) when the unicast DRX retransmission timer is running.
5. The method of claim 2 , comprising:
starting a multicast Discontinuous Reception (DRX) retransmission timer associated with the HARQ process in response to expiry of the multicast HARQ RTT timer.
6. The method of claim 5 , comprising:
monitoring Physical Downlink Control Channel (PDCCH) when the multicast DRX retransmission timer is running.
7. The method of claim 1 , comprising:
not starting the unicast HARQ RTT timer based on the UE not being configured with the CS-RNTI.
8. The method of claim 1 , wherein:
the multicast HARQ RTT Timer is a drx-HARQ-RTT-TimerDL-PTM timer.
9. The method of claim 1 , wherein:
the unicast HARQ RTT timer is a drx-HARQ-RTT-TimerDL timer.
10. A method of a User Equipment (UE), comprising:
receiving a configuration indicative of a feedback mode for multicast transmission;
being configured with a Group Configured Scheduling RNTI (G-CS-RNTI) by a base station, wherein the G-CS-RNTI is used for Semi-Persistent Scheduling (SPS) activation associated with a multicast configured downlink resource;
at least one of receiving or detecting a first multicast transmission of downlink data on the multicast configured downlink resource after SPS activation, wherein the first multicast transmission is associated with a Hybrid Automatic Repeat Request (HARQ) process;
transmitting a negative HARQ feedback for the first multicast transmission;
starting a multicast HARQ Round Trip Time (RTT) timer associated with the HARQ process; and
determining whether to start a unicast HARQ RTT timer associated with the HARQ process based on the feedback mode and whether the UE is configured with a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI).
11. The method of claim 10 , comprising:
starting the unicast HARQ RTT timer based on:
the UE being configured with the CS-RNTI; and
the feedback mode being ack-nack mode.
12. The method of claim 11 , comprising:
starting a unicast Discontinuous Reception (DRX) retransmission timer associated with the HARQ process in response to expiry of the unicast HARQ RTT timer.
13. The method of claim 11 , comprising:
starting a multicast Discontinuous Reception (DRX) retransmission timer associated with the HARQ process in response to expiry of the multicast HARQ RTT timer.
14. The method of claim 10 , comprising:
not starting the unicast HARQ RTT timer based on at least one of:
the UE not being configured with the CS-RNTI; or
the feedback mode being nack-only mode.
15. The method of claim 10 , wherein:
the configuration is a harq-FeedbackOptionMulticast configuration.
16. The method of claim 10 , wherein:
the multicast HARQ RTT Timer is a drx-HARQ-RTT-TimerDL-PTM timer.
17. The method of claim 10 , wherein:
the unicast HARQ RTT timer is a drx-HARQ-RTT-TimerDL timer.
18. A User Equipment (UE) comprising:
a control circuit;
a processor installed in the control circuit; and
a memory installed in the control circuit and operatively coupled to the processor, wherein the processor is configured to execute a program code stored in the memory to perform operations, the operations comprising:
being configured with a Group Configured Scheduling RNTI (G-CS-RNTI) by a base station, wherein the G-CS-RNTI is used for Semi-Persistent Scheduling (SPS) activation associated with a multicast configured downlink resource;
at least one of receiving or detecting a multicast transmission of downlink data on the multicast configured downlink resource after SPS activation, wherein the multicast transmission is associated with a Hybrid Automatic Repeat Request (HARQ) process;
starting a multicast HARQ Round Trip Time (RTT) timer associated with the HARQ process; and
determining whether to start a unicast HARQ RTT timer associated with the HARQ process based on whether the UE is configured with a Configured Scheduling Radio Network Temporary Identifier (CS-RNTI).
19. The UE of claim 18 , the operations comprising:
starting the unicast HARQ RTT timer based on the UE being configured with the CS-RNTI.
20. The UE of claim 18 , the operations comprising:
not starting the unicast HARQ RTT timer based on the UE not being configured with the CS-RNTI.