Reconfigurable intelligent surface enabled sidelink positioning

1. A method of wireless communication performed by a user equipment (UE), comprising:

controlling one or more reconfigurable intelligent surfaces (RIS) in accordance with one or more RIS schedules, wherein the one or more RIS schedules indicate times when the one or more RIS are in an enabled state and times when the one or more RIS are in a disabled state;

requesting at least one participating UE of one or more participating UEs to transmit at least one positioning reference signal (PRS);

performing a first set of one or more measurements of the at least one PRS transmitted from the at least one participating UE, wherein the at least one PRS is measured while performing the first set of one or more measurements in accordance with the RIS schedule to obtain one or more measurements of the at least one PRS when the one or more RIS are in the disabled state; and

performing a second set of one or more measurements of the at least one PRS transmitted from the at least one participating UE, wherein the at least one PRS is measured while performing the second set of one or more measurements in accordance with the RIS schedule to obtain one or more measurements of the at least one PRS when the one or more RIS are in the enabled state.

2. The method of claim 1 , wherein:

the UE is a roadside unit (RSU).

3. The method of claim 1 , wherein:

based on the RIS schedule, at least one measurement from performing the second set of one or more measurements is obtained when the at least one PRS is received from the at least one participating UE over a coherent channel.

4. The method of claim 1 , wherein performing the first set of one or more measurements comprises:

measuring a time-of-arrival (ToA) of the at least one PRS of the at least one participating UE.

5. The method of claim 1 , further comprising:

transmitting a PRS transmission schedule to the at least one participating UE, wherein the PRS transmission schedule requests the at least one participating UE to transmit the at least one PRS at scheduled times indicated by the PRS transmission schedule, and wherein the PRS transmission schedule is determined based on the RIS schedule.

6. The method of claim 1 , further comprising:

determining a range between the UE and the at least one participating UE using the one or more measurements obtained when performing the first set of one or more measurements.

7. The method of claim 6 , wherein:

determining the range between the UE and the at least one participating UE includes using an averaging technique of multiple measurements of the at least one PRS obtained when performing the first set of one or more measurements.

8. The method of claim 6 , further comprising:

determining a range between the at least one participating UE and at least one RIS of the one or more RIS using the one or more measurements of the at least one PRS obtained when performing the second set of one or more measurements.

9. The method of claim 1 , further comprising:

determining a range between the UE and the at least one participating UE using the one or more measurements of the at least one PRS obtained when performing the first set of one or more measurements;

determining a range between the at least one participating UE and at least one RIS of the one or more RIS using the one or more measurements of the at least one PRS obtained when performing the second set of one or more measurements; and

determining a position of the at least one participating UE using the range between the UE and the at least one participating UE, the range between the at least one participating UE and the at least one RIS, a known position of the UE, and a known position of the at least one RIS.

10. A method of wireless communication performed by a first user equipment (UE), comprising:

receiving, from a second UE, a reconfigurable intelligent surface (RIS) schedule, wherein the RIS schedule indicates times when at least one RIS of one or more RIS resources is in an enabled state and times when the at least one RIS of the one or more RIS is in a disabled state;

receiving, from the second UE, a positioning reference signal (PRS) measurement schedule, wherein the PRS measurement schedule indicates times when at least one PRS from the second UE may be measured by the first UE;

performing a first set of one or more measurements of the at least one PRS transmitted from the second UE in accordance with the PRS measurement schedule and the RIS schedule to obtain one or more measurements of the at least one PRS when the at least one RIS is in the disabled state; and

performing a second set of one or more measurements of the at least one PRS transmitted from the second UE in accordance with the PRS measurement schedule and the RIS schedule to obtain one or more measurements of the at least one PRS when the at least one RIS is in the enabled state.

11. The method of claim 10 , wherein:

the second UE is a roadside unit (RSU).

12. The method of claim 10 , further comprising:

coordinating the PRS measurement schedule and RIS schedule such that at least one measurement obtained when performing the first set of one or more measurements is obtained when the at least one PRS is received from the second UE over a coherent channel.

13. The method of claim 10 , wherein performing the first set of one or more measurements, comprises:

determining a time-of-arrival of the at least one PRS corresponding to a direct path measurement of the at least one PRS.

14. The method of claim 13 , wherein performing the second set of one or more measurements, comprises:

determining a time-of-arrival of the at least one PRS corresponding to a direct path measurement of the at least one PRS; and

determining a time-of-arrival of the at least one PRS corresponding to a reflective path measurement of the at least one PRS as reflected by the at least one RIS.

15. The method of claim 14 , further comprising:

transmitting, by the first UE, at least one PRS when the at least one RIS is in the enabled state;

transmitting, by the first UE, at least one PRS when the at least one RIS is in the disabled state;

receiving a report from the second UE, wherein the report indicates

a first time-of-arrival measurement of the at least one PRS transmitted by the first UE made by the second UE when the at least one RIS is in the disabled state, wherein the first time-of-arrival measurement corresponds to a direct path measurement of the at least one PRS;

a second time-of-arrival measurement of the at least one PRS transmitted by the first UE made by the second UE when the at least one RIS is in the enabled state, wherein the second time-of-arrival measurement corresponds to a direct path measurement of the at least one PRS; and

a third time-of-arrival measurement of the at least one PRS transmitted by the first UE made by the second UE when the at least one RIS is in the enabled state, wherein the third time-of-arrival measurement corresponds to a reflective path measurement of the at least one PRS of the first UE from the at least one RIS.

16. The method of claim 15 , further comprising:

sending, to the second UE, a first time-of-transmission of the at least one PRS transmitted by the first UE when the at least one RIS is in the enabled state; and

sending, to the second UE, a second time-of-transmission of the at least one PRS transmitted by the first UE when the at least one RIS is in the disabled state.

17. The method of claim 16 , wherein:

the report indicates the first time-of-arrival as a difference measurement with respect to the first time-of-transmission;

the report indicates the second time-of-arrival as a difference measurement with respect to the second time-of-transmission; and

the report indicates the third time-of-arrival as a difference measurement with respect to the second time-of-transmission.

18. The method of claim 10 , further comprising:

determining a range between the first UE and the second UE using the one or more measurements obtained when performing the first set of one or more measurements.

19. The method of claim 18 , wherein:

determining the range between the first UE and the second UE includes using an averaging technique of multiple measurements obtained when performing the first set of one or more measurements.

20. The method of claim 10 , further comprising:

determining a range between the first UE and the at least one RIS of the one or more RIS using the one or more measurements obtained when performing the second set of one or more measurements.

21. The method of claim 10 , further comprising:

receiving, from the second UE, a known position of the second UE; and

receiving, from the second UE, a position of the at least one RIS of the one or more RIS.

22. The method of claim 21 , further comprising:

determining a range between the first UE and the second UE using the one or more measurements obtained when performing the first set of one or more measurements;

determining a range between the first UE and the at least one RIS using the one or more measurements obtained when performing the second set of one or more measurements; and

determining a position of the first UE using the range between the first UE and the second UE, the range between the first UE and the at least one RIS, the known position of the second UE, and the known position of the at least one RIS.

23. A user equipment (UE), comprising:

a memory;

at least one transceiver; and

at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to:

control one or more reconfigurable intelligent surfaces (RIS) in accordance with one or more RIS schedules, wherein the one or more RIS schedules indicate times when the one or more RIS are in an enabled state and times when the one or more RIS are in a disabled state;

request at least one participating UE of one or more participating UEs to transmit at least one positioning reference signal (PRS);

perform a first set of one or more measurements of the at least one PRS transmitted from the at least one participating UE, wherein the at least one PRS is measured while performing the first set of one or more measurements in accordance with the RIS schedule to obtain one or more measurements of the at least one PRS when the one or more RIS are in the disabled state; and

perform a second set of one or more measurements of the at least one PRS transmitted from the at least one participating UE, wherein the at least one PRS is measured while performing the second set of one or more measurements in accordance with the RIS schedule to obtain one or more measurements of the at least one PRS when the one or more RIS are in the enabled state.

24. The UE of claim 23 , wherein:

the UE is a roadside unit (RSU).

25. The UE of claim 23 , wherein:

based on the RIS schedule, at least one measurement from performing the second set of one or more measurements is obtained when the at least one PRS is received from the at least one participating UE over a coherent channel.

26. The UE of claim 23 , wherein, to perform the first set of one or more measurements, the at least one processor is configured to:

measure a time-of-arrival (ToA) of the at least one PRS of the at least one participating UE.

27. The UE of claim 23 , wherein the at least one processor is further configured to:

transmit, via the at least one transceiver, a PRS transmission schedule to the at least one participating UE, wherein the PRS transmission schedule requests the at least one participating UE to transmit the at least one PRS at scheduled times indicated by the PRS transmission schedule, and wherein the PRS transmission schedule is determined based on the RIS schedule.

28. The UE of claim 23 , wherein the at least one processor is further configured to:

determine a range between the UE and the at least one participating UE using the one or more measurements obtained when performing the first set of one or more measurements.

29. The UE of claim 28 , wherein:

determine the range between the UE and the at least one participating UE includes using an averaging technique of multiple measurements of the at least one PRS obtained when performing the first set of one or more measurements.

30. The UE of claim 28 , wherein the at least one processor is further configured to:

determine a range between the at least one participating UE and at least one RIS of the one or more RIS using the one or more measurements of the at least one PRS obtained when performing the second set of one or more measurements.

31. The UE of claim 23 , wherein the at least one processor is further configured to:

determine a range between the UE and the at least one participating UE using the one or more measurements of the at least one PRS obtained when performing the first set of one or more measurements;

determine a range between the at least one participating UE and at least one RIS of the one or more RIS using the one or more measurements of the at least one PRS obtained when performing the second set of one or more measurements; and

determine a position of the at least one participating UE using the range between the UE and the at least one participating UE, the range between the at least one participating UE and the at least one RIS, a known position of the UE, and a known position of the at least one RIS.

32. A first user equipment (UE), comprising:

a memory;

at least one transceiver; and

at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to:

receive, via the at least one transceiver, from a second UE, a reconfigurable intelligent surface (RIS) schedule, wherein the RIS schedule indicates times when at least one RIS of one or more RIS resources is in an enabled state and times when the at least one RIS of the one or more RIS is in a disabled state;

receive, via the at least one transceiver, from the second UE, a positioning reference signal (PRS) measurement schedule, wherein the PRS measurement schedule indicates times when at least one PRS from the second UE may be measured by the first UE;

perform a first set of one or more measurements of the at least one PRS transmitted from the second UE in accordance with the PRS measurement schedule and the RIS schedule to obtain one or more measurements of the at least one PRS when the at least one RIS is in the disabled state; and

perform a second set of one or more measurements of the at least one PRS transmitted from the second UE in accordance with the PRS measurement schedule and the RIS schedule to obtain one or more measurements of the at least one PRS when the at least one RIS is in the enabled state.

33. The first UE of claim 32 , wherein:

the second UE is a roadside unit (RSU).

34. The first UE of claim 32 , wherein the at least one processor is further configured to:

coordinate the PRS measurement schedule and RIS schedule such that at least one measurement obtained when performing the first set of one or more measurements is obtained when the at least one PRS is received from the second UE over a coherent channel.

35. The first UE of claim 32 , wherein, to perform the first set of one or more measurements, the at least one processor is configured to:

determine a time-of-arrival of the at least one PRS corresponding to a direct path measurement of the at least one PRS.

36. The first UE of claim 35 , wherein, to perform the second set of one or more measurements, the at least one processor is configured to:

determine a time-of-arrival of the at least one PRS corresponding to a direct path measurement of the at least one PRS; and

determine a time-of-arrival of the at least one PRS corresponding to a reflective path measurement of the at least one PRS as reflected by the at least one RIS.

37. The first UE of claim 36 , wherein the at least one processor is further configured to:

transmit, via the at least one transceiver, at least one PRS when the at least one RIS is in the enabled state;

transmit, via the at least one transceiver, at least one PRS when the at least one RIS is in the disabled state;

receive, via the at least one transceiver, a report from the second UE, wherein the report indicates

a first time-of-arrival measurement of the at least one PRS transmitted by the first UE made by the second UE when the at least one RIS is in the disabled state, wherein the first time-of-arrival measurement corresponds to a direct path measurement of the at least one PRS;

a second time-of-arrival measurement of the at least one PRS transmitted by the first UE made by the second UE when the at least one RIS is in the enabled state, wherein the second time-of-arrival measurement corresponds to a direct path measurement of the at least one PRS; and

a third time-of-arrival measurement of the at least one PRS transmitted by the first UE made by the second UE when the at least one RIS is in the enabled state, wherein the third time-of-arrival measurement corresponds to a reflective path measurement of the at least one PRS of the first UE from the at least one RIS.

38. The first UE of claim 37 , wherein the at least one processor is further configured to:

send, via the at least one transceiver, to the second UE, a first time-of-transmission of the at least one PRS transmitted by the first UE when the at least one RIS is in the enabled state; and

send, via the at least one transceiver, to the second UE, a second time-of-transmission of the at least one PRS transmitted by the first UE when the at least one RIS is in the disabled state.

39. The first UE of claim 32 , wherein the at least one processor is further configured to:

determine a range between the first UE and the second UE using the one or more measurements obtained when performing the first set of one or more measurements; and

determine a range between the first UE and the at least one RIS of the one or more RIS using the one or more measurements obtained when performing the second set of one or more measurements.

40. The first UE of claim 32 , wherein the at least one processor is further configured to:

receive, via the at least one transceiver, from the second UE, a known position of the second UE;

receive, via the at least one transceiver, from the second UE, a position of the at least one RIS of the one or more RIS;

determine a range between the first UE and the second UE using the one or more measurements obtained when performing the first set of one or more measurements;

determine a range between the first UE and the at least one RIS using the one or more measurements obtained when performing the second set of one or more measurements; and

determine a position of the first UE using the range between the first UE and the second UE, the range between the first UE and the at least one RIS, the known position of the second UE, and the known position of the at least one RIS.