Method and apparatus for PDCCH monitoring in a wireless communication system
A method and apparatus are disclosed. In an example from the perspective of a User Equipment (UE), a signal to configure the UE to perform a Random Access Channel-less (RACH-less) handover to a second cell may be received in a first cell, wherein the signal comprises a candidate list of beams for Physical Downlink Control Channel (PDCCH) monitoring in the second cell and/or the signal is indicative of a first beam of the candidate list of beams (to be used by the UE for PDCCH monitoring). A PDCCH in the second cell on the first beam may be monitored before receiving a Medium Access Control (MAC) Control Element (CE) assigning a second beam for PDCCH monitoring in the second cell.
1. A method of a User Equipment (UE), comprising:
receiving, in a first cell, a signal to configure the UE to perform a Random Access Channel-less (RACH-less) handover to a second cell, wherein:
the signal comprises a candidate list of beams for Physical Downlink Control Channel (PDCCH) monitoring in the second cell; and
the signal is indicative of a first beam of the candidate list of beams; and
monitoring, in the second cell, a PDCCH on the first beam indicated in the signal received in the first cell before receiving a Medium Access Control (MAC) Control Element (CE) assigning a second beam for PDCCH monitoring in the second cell.
2. The method of claim 1 , wherein the signal is a Radio Resource Control (RRC) reconfiguration message.
3. The method of claim 1 , wherein the signal configures at least one of RACH-less, RACH-skip or RACH-skipSCG.
4. The method of claim 1 , wherein the candidate list of beams is a Transmission Configuration Indicator (TCI) states PDCCH list.
5. The method of claim 1 , wherein at least one of the first beam or the second beam is a TCI state.
6. The method of claim 1 , wherein the MAC CE is an indication of a TCI state for UE-specific PDCCH.
7. The method of claim 1 , wherein the MAC CE comprises information of at least one of a serving cell identification, a bandwidth part (BWP) identification, a control resource set (CORESET) identification or a TCI state identification.
8. A method of a User Equipment (UE), comprising:
receiving a first Medium Access Control (MAC) Control Element (CE) assigning a first beam for Physical Downlink Control Channel (PDCCH) monitoring in a first cell;
monitoring, in the first cell, a first PDCCH on the first beam assigned for PDCCH monitoring in the first cell based upon the first MAC CE; and
monitoring, in a second cell, a second PDCCH on the first beam assigned for PDCCH monitoring in the first cell based upon the first MAC CE before receiving a second MAC CE assigning a second beam for PDCCH monitoring in the second cell.
9. The method of claim 8 , wherein at least one of the first MAC CE or the second MAC CE is an indication of a TCI state for UE-specific PDCCH.
10. The method of claim 8 , wherein the first MAC CE is received via at least one of the first cell, the second cell or a different cell.
11. The method of claim 8 , wherein the second MAC CE is received via at least one of the first cell, the second cell or a different cell.
12. The method of claim 8 , wherein at least one of the first MAC CE or the second MAC CE comprises information of at least one of a serving cell identification, a bandwidth part (BWP) identification, a control resource set (CORESET) identification or a TCI state identification.
13. The method of claim 8 , further comprising:
receiving, in the first cell, a signal to configure the UE to perform a Random Access Channel-less (RACH-less) handover to the second cell, wherein the signal is a Radio Resource Control (RRC) reconfiguration message.
14. The method of claim 13 , wherein the signal configures at least one of RACH-less, RACH-skip or RACH-skipSCG.
15. A method of a User Equipment (UE), comprising:
receiving, in a first cell, a signal to configure the UE to perform a Random Access Channel-less (RACH-less) handover to a second cell, wherein:
the signal comprises an uplink (UL) grant and an association between the UL grant and a downlink (DL) signal; and
monitoring, in the second cell, a PDCCH on a beam associated with the DL signal associated with the UL grant in the signal received in the first cell.
16. The method of claim 15 , wherein the signal is a Radio Resource Control (RRC) reconfiguration message.
17. The method of claim 15 , wherein the signal configures at least one of RACH-less, RACH-skip or RACH-skipSCG.
18. The method of claim 15 , wherein the UL grant is at least one of a periodic UL grant or a pre-allocated UL grant.
19. The method of claim 15 , wherein the UL grant is used in the second cell.
20. The method of claim 15 , wherein the DL signal is at least one of a Synchronization Signal Block (SSB) or a Channel State Information based Reference Signal (CSI-RS).