Sensing operations for sidelink communications
Methods and apparatuses for adaptive low-power sensing operations for sidelink (SL) communications in a wireless communication system. A method of operating a user equipment (UE) includes operating with partial sensing; operating in a resource pool configured for the partial sensing; and triggering for a SL resource selection in a slot n. The method further includes selecting Y candidate slots for the SL resource selection and performing, in a sensing window, a contiguous partial sensing (CPS). A first of the selected Y candidate slots is a slot t′ y0 SL . The sensing window is in contiguous slots within the resource pool relative to the slot t′ y0 SL .
1. A user equipment (UE), comprising:
a transceiver; and
a processor operably coupled to the transceiver, the processor configured to:
operate with partial sensing;
operate in a resource pool configured for the partial sensing;
trigger a sidelink (SL) resource selection in a slot n;
select Y candidate slots for the SL resource selection, wherein a first of the selected Y candidate slots is a slot t′ y0 SL ; and
perform, in a sensing window, a contiguous partial sensing (CPS), wherein:
the sensing window is in contiguous slots within the resource pool relative to the slot t′ y0 SL ,
an end of the sensing window is T proc,0 SL +T proc,1 SL before the slot t′ y0 SL ,
T proc,0 SL is a sensing processing latency time, and
T proc,1 SL is a resource selection processing time.
2. The UE of claim 1 , wherein a start of the sensing window is one of:
31 logical slots before the slot t′ y0 SL , or
a configured number of logical slots before the slot t′ y0 SL .
3. The UE of claim 1 , wherein a start of the sensing window is no earlier than the slot n.
4. The UE of claim 1 , wherein:
the resource pool has a parameter sl-MultiReserveResource set to enabled; and
the processor is further configured to perform periodic-based partial sensing (PBPS).
5. The UE of claim 4 , wherein the selected Y candidate slots are for the CPS and the PBPS.
6. The UE of claim 4 , wherein the processor is further configured to perform PBPS for a re-evaluation check or a pre-emption check.
7. The UE of claim 1 , wherein:
the processor is further configured to trigger a re-evaluation check or a pre-emption check in the slot n,
a slot t′ yi SL replaces the slot t′ y0 SL , and
the slot t′ yi SL is a first slot with a SL resource for a re-evaluation check or a pre-emption check after the slot n+T 3 , where T 3 is a resource selection processing time for re-evaluation check or pre-emption check.
8. The UE of claim 1 , wherein:
the processor is further configured to determine candidate resources in a slot R, and
the slot R is the resource selection processing time, T proc,1 SL , before the slot t′ y0 SL .
9. The UE of claim 1 , wherein the processor is further configured to:
measure a SL channel busy ratio (CBR) over a window [m−a, m−1], where m is a slot in which the received signal strength indicator (RSSI) is measured and a is determined according to a higher layer parameter sl-TimeWindowSizeCBR, and
determine the CBR based on the RSSI measured in slots within the window, wherein partial sensing is performed and a number of the slots is X; and
use the measured CBR when X is not less than a pre-configured value.
10. A method of operating a user equipment (UE), the method comprising:
operating with partial sensing;
operating in a resource pool configured for the partial sensing;
triggering for a sidelink (SL) resource selection in a slot n;
selecting Y candidate slots for the SL resource selection, wherein a first of the selected Y candidate slots is a slot t′ y0 SL ; and
performing, in a sensing window, a contiguous partial sensing (CPS), wherein:
the sensing window is in contiguous slots within the resource pool relative to the slot t′ y0 SL ,
an end of the sensing window is T proc,0 SL +T proc,1 SL before the slot t′ y0 SL ,
T proc,0 SL is a sensing processing latency time, and
T proc,1 SL is a resource selection processing time.
11. The method of claim 10 , wherein a start of the sensing window is one of:
31 logical slots before the slot t′ y0 SL , or
a configured number of logic slots before the slot t′ y0 SL .
12. The method of claim 10 , wherein a start of the sensing window is no earlier than the slot n.
13. The method of claim 10 , wherein:
the resource pool has a parameter sl-MultiReserveResource set to enabled; and
the method further comprises performing periodic-based partial sensing (PBPS).
14. The method of claim 13 , wherein the selected Y candidate slots are for the CPS and the PBPS.
15. The method of claim 13 , further comprising performing PBPS for a re-evaluation check and a pre-emption check.
16. The method of claim 10 , further comprising:
triggering a re-evaluation check or a pre-emption check in the slot n,
wherein a slot t′ yi SL replaces the slot t′ y0 SL , and
the slot t′ yi SL is a first slot with a SL resource for a re-evaluation check or a pre-emption check after the slot n+T 3 , where T 3 is a resource selection processing time for re-evaluation check or pre-emption check.
17. The method of claim 10 , further comprising:
determining candidate resources in a slot R,
wherein the slot R is the resource selection processing time, T proc,1 SL , before the slot t′ y0 SL .
18. The method of claim 10 , further comprising:
measuring a SL channel busy ratio (CBR) over a window [m−a, m−1], where m is a slot in which the received signal strength indicator (RSSI) is measured and a is determined according to a higher layer parameter sl-TimeWindowSizeCBR;
determining the CBR based on the RSSI measured in slots, within the window, wherein partial sensing is performed and a number of the slots is X; and
using the measured CBR when X is not less than a pre-configured value.