Reconfigurable intelligent surface (RIS)-aided UE passive RF sensing
Techniques are disclosed for determining an object's location by using a Reconfigurable Intelligent Surface (RIS) to aid in RF sensing. Radar techniques can be used in which one or more base stations act as a transmitter and a receiving device acts as a receiver in a bistatic or multi-static radar configuration where an RIS directs signals transmitted by the one or more base stations to the receiving device. By comparing the time a line-of-sight (LOS) signal (redirected to the receiving device by the RIS) is received by the receiving device with that of an echo signal (redirected to the receiving device by the RIS) from a reflection of an RF signal from the object, a position of the object can be determined. Depending on desired functionality, this position can be determined by the receiving device or by a location server or other network entity.
1. A method of performing radio frequency (RF) sensing with a receiving device and a reconfigurable intelligent surface (RIS) in a wireless communications system, the method comprising:
configuring the RIS to reflect a Line-Of-Sight (LOS) wireless signal toward the receiving device, wherein the LOS wireless signal comprises a first wireless reference signal transmitted by a Transmission Reception Point (TRP) of the wireless communications system;
configuring the RIS to reflect an echo signal toward the receiving device, wherein the echo signal comprises a reflection, off of an object, of a second wireless reference signal transmitted by the TRP of the wireless communications system;
determining a position of the object based on:
a position of the RIS relative to the TRP, and
a time difference between a first Time of Arrival (ToA) of the LOS wireless signal at the receiving device and a second ToA of the echo signal at the receiving device; and
providing the position of the object.
2. The method of claim 1 , wherein configuring the RIS to reflect the LOS wireless signal and the echo signal toward the receiving device comprises controlling the RIS with the TRP or a server.
3. The method of claim 2 , wherein the server controls the RIS, and wherein the server further:
determines a position of the receiving device; and
configures the RIS to reflect the LOS wireless signal and the echo signal toward the receiving device based on the position of the receiving device.
4. The method of claim 1 , further comprising including, in the first wireless reference signal and the second wireless reference signal, an identifier of the RIS.
5. The method of claim 1 , wherein the receiving device comprises a mobile device or another TRP.
6. The method of claim 1 , wherein the receiving device determines the position of the object.
7. The method of claim 6 , further comprising determining, with the receiving device, a receive angle comprising an angle at which the echo signal is received at the RIS, and wherein the receiving device determines the position of the object additionally based on the receive angle.
8. The method of claim 6 , further comprising determining, with the receiving device, a time gap comprising a difference between a time the TRP transmits the first wireless reference signal and a time the TRP transmits the second wireless reference signal, wherein determining the position of the object is further based on the time gap.
9. The method of claim 8 , wherein determining the time gap comprises receiving an indication of the time gap from a server.
10. The method of claim 6 , wherein providing the position of the object comprises providing the position of the object to an application executed by the receiving device.
11. The method of claim 6 , further comprising sending information indicative of the position of the RIS relative to the TRP from a server to the receiving device.
12. The method of claim 1 , wherein a server determines the position of the object.
13. The method of claim 12 , further comprising:
receiving, at the server, information indicative of the first ToA and the second ToA from the receiving device; and
determining, with the server, the time difference between the first ToA and the second ToA from the information indicative of the first ToA and the second ToA.
14. The method of claim 12 , further comprising:
determining, with the server based on multilateration from information received from a plurality of receiving devices, a receive angle comprising angle at which the echo signal is received at the RIS;
wherein the server determines the position of the object additionally based on the receive angle.
15. The method of claim 12 , further comprising determining, with the server, a time gap comprising a difference between a time the TRP transmits the first wireless reference signal and a time the TRP transmits the second wireless reference signal, wherein determining the position of the object is further based on the time gap.
16. The method of claim 1 , further comprising configuring the RIS to adjust a phase, a magnitude, or both of either or both the LOS wireless signal or the echo signal.
17. A device comprising:
a transceiver;
a memory; and
one or more processing units communicatively coupled with the transceiver and the memory, the one or more processing units configured to:
configure a reconfigurable intelligent surface (RIS) to reflect a Line-Of-Sight (LOS) wireless signal toward a receiving device, wherein the LOS wireless signal comprises a first wireless reference signal transmitted by a Transmission Reception Point (TRP) of a wireless communications system;
configure the RIS to reflect an echo signal toward the receiving device, wherein the echo signal comprises a reflection, off of an object, of a second wireless reference signal transmitted by the TRP of the wireless communications system;
determine a position of the object based on:
a position of the RIS relative to the TRP, and
a time difference between a first Time of Arrival (ToA) of the LOS wireless signal at the receiving device and a second ToA of the echo signal at the receiving device; and
provide the position of the object.
18. The device of claim 17 , wherein:
the device comprises the TRP or a server; and
to configure the RIS to reflect the LOS wireless signal and the echo signal toward the receiving device, the one or more processing units are configured to control the RIS via the transceiver.
19. The device of claim 18 , wherein the device comprises the server, and wherein the one or more processing units are further configured to:
determine a position of the receiving device; and
configure the RIS to reflect the LOS wireless signal and the echo signal toward the receiving device based on the position of the receiving device.
20. The device of claim 17 , wherein the one or more processing units are further configured to include, in the first wireless reference signal and the second wireless reference signal, an identifier of the RIS.
21. The device of claim 17 , wherein the receiving device comprises a mobile device or another TRP.
22. The device of claim 17 , wherein the device comprises the receiving device.
23. The device of claim 22 , wherein the one or more processing units are further configured to determine a receive angle comprising an angle at which the echo signal is received at the RIS, and wherein the one or more processing units are configured to determine the position of the object additionally based on the receive angle.
24. The device of claim 22 , wherein the one or more processing units are further configured to determine a time gap comprising a difference between a time the TRP transmits the first wireless reference signal and a time the TRP transmits the second wireless reference signal, and wherein the one or more processing units are configured to determine the position of the object is further based on the time gap.
25. The device of claim 24 , wherein, to determine the time gap, the one or more processing units are configured to receive an indication of the time gap from a server.
26. The device of claim 22 , wherein, to provide the position of the object, the one or more processing units are configured to provide the position of the object to an application executed by the receiving device.
27. The device of claim 22 , wherein the one or more processing units are configured to receive, via the transceiver, information indicative of the position of the RIS relative to the TRP from a server.
28. The device of claim 17 , wherein the device comprises a server.
29. The device of claim 28 , wherein the one or more processing units are configured to:
receive, via the transceiver, information indicative of the first ToA and the second ToA from the receiving device; and
determine the time difference between the first ToA and the second ToA from the information indicative of the first ToA and the second ToA.
30. The device of claim 28 , wherein the one or more processing units are configured to:
determine, based on multilateration from information received from a plurality of receiving devices, a receive angle comprising angle at which the echo signal is received at the RIS; and
determine the position of the object additionally based on the receive angle.
31. The device of claim 28 , wherein the one or more processing units are configured to:
determine a time gap comprising a difference between a time the TRP transmits the first wireless reference signal and a time the TRP transmits the second wireless reference signal; and
determine the position of the object additionally based on the time gap.
32. The device of claim 17 , wherein the one or more processing units are configured to configure the RIS to adjust a phase, a magnitude, or both of either or both the LOS wireless signal or the echo signal.
33. A device comprising:
means for configuring a reconfigurable intelligent surface (RIS) to reflect a Line-Of-Sight (LOS) wireless signal toward a receiving device, wherein the LOS wireless signal comprises a first wireless reference signal transmitted by a Transmission Reception Point (TRP) of a wireless communications system;
means for configuring the RIS to reflect an echo signal toward the receiving device, wherein the echo signal comprises a reflection, off of an object, of a second wireless reference signal transmitted by the TRP of the wireless communications system;
means for determining a position of the object based on:
a position of the RIS relative to the TRP, and
a time difference between a first Time of Arrival (ToA) of the LOS wireless signal at the receiving device and a second ToA of the echo signal at the receiving device; and
means for providing the position of the object.
34. The device of claim 33 , wherein the means for configuring the RIS to reflect the LOS wireless signal and the echo signal toward the receiving device comprises means for controlling the RIS with the TRP or a server.
35. The device of claim 33 , wherein the device comprises the receiving device.
36. The device of claim 33 , wherein the device comprises a server.
37. A non-transitory computer-readable medium storing instructions for performing radio frequency (RF) sensing with a receiving device and a reconfigurable intelligent surfaces (RIS) in a wireless communications system, the instructions comprising code for:
configuring the RIS to reflect a Line-Of-Sight (LOS) wireless signal toward a receiving device, wherein the LOS wireless signal comprises a first wireless reference signal transmitted by a Transmission Reception Point (TRP) of the wireless communications system;
configuring the RIS to reflect an echo signal toward the receiving device, wherein the echo signal comprises a reflection, off of an object, of a second wireless reference signal transmitted by the TRP of the wireless communications system;
determining a position of the object based on:
a position of the RIS relative to the TRP, and
a time difference between a first Time of Arrival (ToA) of the LOS wireless signal at the receiving device and a second ToA of the echo signal at the receiving device; and
providing the position of the object.