Mechanism for SSB transmission in NR-U
The present application is directed to an apparatus including a non-transitory memory including instructions stored thereon for monitoring synchronous signals and physical broadcast channels (SSBs) from a network node. The apparatus also includes a processor, operably coupled to the non-transitory memory, configured to execute a set of instructions. The instructions include configuring the apparatus for a STTC (SSB Transmission Timing Configuration). The STTC is a time interval with plural locations accommodating transmission of the SSBs. The instructions also include monitoring the STTC for the SSBs. The instructions further include determining a first one of the SSBs in a first slot of a subframe in a scheduled SSB transmission in the STTC has been transmitted at a first scheduled location, where the transmission of the first one of the SSBs is based upon confirmation of a successful Listen Before Talk (LBT) available channel prior to the scheduled SSB transmission in the STTC.
1. A wireless transmit/receive unit comprising:
a non-transitory memory including instructions stored thereon for monitoring synchronous signal blocks (SSBs) in unlicensed spectrum; and
a processor, operably coupled to the non-transitory memory, configured to execute the instructions of:
determining a length of an SSB transmission timing window, wherein the length of the SSB transmission timing within is determined based on a received an SSB transmission timing configuration (STTC) on condition that the STTC is received from a network node, and the SSB transmission timing window is determined to be predefined length of 5 ms on condition that the STTC is not received from the network node;
monitoring for the SSBs based on the STTC in accordance with the SSB transmission timing window;
receiving at least one SSB in the SSB transmission timing window; and
receiving a physical broadcast channel (PBCH) demodulation reference signal (DMRS) and a PBCH payload;
determining an offset based on the PBCH DMRS and the PBCH payload; and
determining a frame boundary based on information indicating the offset of the received SSB.
2. The wireless transmit/receive unit of claim 1 , wherein the processor is further configured to execute the instructions of determining, from among the SSBs, a second SSB in the STTC at a second scheduled location.
3. The wireless transmit/receive unit of claim 1 , wherein the information is indicated via a physical broadcast channel (PBCH), payload of the PBCH and an initialization of a PBCH demodulation reference signal (DMRS) sequence.
4. The wireless transmit/receive unit of claim 3 , wherein the processor is further configured to execute the instructions of:
receiving an SSB index of the SSB transmission in the STTC.
5. The wireless transmit/receive unit of claim 4 , wherein the SSB index is based upon one or more of a payload of a physical broadcast channel and a physical broadcast channel demodulation reference signal, and
wherein the processor is further configured to execute the instructions of determining a radio frame boundary based upon the offset and an SSB block index.
6. The wireless transmit/receive unit of claim 3 , wherein the STTC is fixed for initial cell selection for the network node.
7. The wireless transmit/receive unit of claim 3 , wherein the processor is further configured to execute the instructions of determining a radio frame boundary based upon the offset and an SSB block index.
8. The wireless transmit/receive unit of claim 3 , wherein an available channel is in an unlicensed spectrum.
9. The wireless transmit/receive unit of claim 1 , wherein a time duration of the STTC is configured via radio resource control (RRC) signaling.
10. A method implemented by a wireless transmit/receive unit, the method comprising:
determining a length of an SSB transmission timing window, wherein the length of the SSB transmission timing within is determined based on a received an SSB transmission timing configuration (STTC) on condition that the STTC is received from a network node, and the SSB transmission timing window is determined to be predefined length of 5 ms on condition that the STTC is not received from the network node;
monitoring for the SSBs based on the STTC in accordance with the SSB transmission timing window;
receiving at least one SSB in the SSB transmission timing window;
receiving a physical broadcast channel (PBCH) demodulation reference signal (DMRS) and a PBCH payload;
determining an offset based on the PBCH DMRS and the PBCH payload; and
determining a frame boundary based on information indicating the offset of the received SSB.
11. The method of claim 10 , further comprising:
determining, from among the SSBs, a second SSB in the STTC at a second scheduled location.
12. The method of claim 10 , wherein the information is indicated via a physical broadcast channel (PBCH), payload of the PBCH and an initialization of a PBCH demodulation reference signal (DMRS) sequence.
13. The method of claim 12 , further comprising:
receiving an SSB index of the SSB transmission in the STTC.
14. The method of claim 13 , wherein the SSB index is based upon one or more of a payload of a physical broadcast channel and a physical broadcast channel demodulation reference signal, and further comprising:
determining a radio frame boundary based upon the offset and an SSB block index.
15. The method of claim 12 , wherein the STTC is fixed for initial cell selection for the network node.
16. The method of claim 12 , further comprising:
determining a radio frame boundary based upon the offset and an SSB block index.
17. The method of claim 12 , wherein an available channel is in an unlicensed spectrum.
18. The method of claim 10 , wherein a time duration of the STTC is configured via radio resource control (RRC) signaling.
19. A wireless transmit/receive unit (WTRU) comprising:
a processor and memory, wherein the processor and memory are configured to:
determine a length of an SSB transmission timing window, wherein the length of the SSB transmission timing within is determined based on a received an SSB transmission timing configuration (STTC) on condition that the STTC is received from a network node, and the SSB transmission timing window is determined to be predefined length of 5 ms on condition that the STTC is not received from the network node;
monitor for the SSBs based on the STTC in accordance with the SSB transmission timing window;
receive at least one SSB in the SSB transmission timing window;
receive a physical broadcast channel (PBCH) demodulation reference signal (DMRS) and a PBCH payload;
determine an offset based on the PBCH DMRS and the PBCH payload; and
determine a frame boundary based on information indicating the offset of the received SSB.
20. The WTRU of claim 19 , wherein the information is indicated via a physical broadcast channel (PBCH), payload of the PBCH and an initialization of a PBCH demodulation reference signal (DMRS) sequence.