Method and apparatus for channel access in a wireless communication system
A method and apparatus are disclosed. In an example from the perspective of a base station, the UE performs a first transmission without Listen Before Talk (LBT), wherein the first transmission is a Synchronization Signal Block (SSB) transmission. The UE performs LBT for a second transmission for a signal other than SSB.
1 . A method of a base station, the method comprising:
determining, by the base station, whether or not to perform Listen Before Talk (LBT) for a first transmission based on whether or not the first transmission is a Synchronization Signal Block (SSB) transmission;
performing, by the base station, the first transmission without LBT based on a determination that the first transmission is the SSB transmission;
determining, by the base station, whether or not to perform LBT for a second transmission based on whether or not the second transmission is for a signal other than SSB; and
performing, by the base station, LBT for the second transmission based on a determination that the second transmission is for the signal other than SSB.
2 . The method of claim 1 , wherein:
the signal other than SSB is a Channel State Information Reference Signal (CSI-RS).
3 . The method of claim 1 , wherein:
the signal other than SSB is a Physical Downlink Control Channel (PDCCH).
4 . The method of claim 1 , wherein:
the signal other than SSB associated with the second transmission for which LBT was performed is a Physical Downlink Shared Channel (PDSCH).
5 . The method of claim 1 , wherein:
the base station operates in a shared spectrum.
6 . The method of claim 1 , further comprising:
determining whether or not to perform LBT for a transmission based on whether or not the transmission is the SSB transmission.
7 . The method of claim 1 , wherein:
performing LBT for the second transmission is based on the second transmission being a Physical Downlink Control Channel (PDCCH) transmission.
8 . The method of claim 1 , wherein the first transmission and the second transmission are at least one of:
on a same serving cell;
on a same spectrum; or
on a same carrier.
9 . A method of a base station, the method comprising:
transmitting a first signal on a channel without sensing the channel, wherein the first signal comprises a Synchronization Signal Block (SSB);
determining whether or not to sense the channel for a transmission of a second signal on the channel based on whether or not the transmission of the second signal on the channel comprises a SSB transmission;
sensing the same channel on which the first signal was transmitted without sensing the channel for the transmission of the second signal based on a determination that the second signal does not comprise a SSB; and
transmitting the second signal on the same channel on which the first signal was transmitted without sensing the channel after sensing the channel.
10 . The method of claim 9 , wherein:
the second signal is a Channel State Information Reference Signal (CSI-RS).
11 . The method of claim 9 , wherein:
the second signal is a Physical Downlink Control Channel (PDCCH).
12 . The method of claim 9 , wherein:
the second signal is a Physical Downlink Shared Channel (PDSCH).
13 . The method of claim 9 , wherein:
the base station operates in a shared spectrum.
14 . The method of claim 9 , further comprising:
determining whether or not to sense the channel for a transmission on the channel based on whether or not the transmission on the channel is a SSB transmission.
15 . The method of claim 9 , wherein:
transmitting the first signal on the channel without sensing the channel is performed based on the first signal comprising the SSB.
16 . The method of claim 9 , wherein the first signal and the second signal are transmitted on at least one of:
a same serving cell;
a same spectrum; or
a same carrier.
17 . A base station, comprising:
a control circuit;
a processor installed in the control circuit; and
a memory installed in the control circuit and coupled to the processor, wherein the processor is configured to execute a program code stored in the memory to perform operations, the operations comprising:
transmitting a first signal on a channel without sensing the channel, wherein the first signal comprises a Synchronization Signal Block (SSB);
determining whether or not to sense the channel for a transmission of a second signal on the channel based on whether or not the transmission of the second signal on the channel comprises a SSB transmission;
sensing the same channel on which the first signal was transmitted without sensing the channel for the transmission of the second signal based on a determination that the second signal does not comprise the SSB; and
transmitting the second signal on the same channel on which the first signal was transmitted without sensing the channel after sensing the channel.
18 . The base station of claim 17 , wherein:
the second signal is a Channel State Information Reference Signal (CSI-RS).
19 . The method of claim 1 , comprising:
determining, by the base station, whether or not to perform LBT for the second transmission based on whether or not the second transmission is an SSB transmission,
wherein performing the LBT for the second transmission is based on a determination that the second transmission is for a signal other than SSB.
20 . The method of claim 1 , wherein:
the signal other than SSB is a Physical Downlink Control Channel (PDCCH) scheduling user plane data.
21 . The method of claim 1 , wherein:
the signal other than SSB is a unicast Physical Downlink Shared Channel (PDSCH) with user plane data.