Single-antenna tracking of moving target

1 . An apparatus for wireless communication at a first user equipment (UE), comprising:

at least one memory; and

at least one processor coupled to the at least one memory, the at least one processor, individually or in any combination, is configured to:

track a first set of displacements of the first UE relative to a first reference frame of the first UE during a ranging session;

transmit, to a second UE, an indication to track a second set of displacements of the second UE relative to a second reference frame of the second UE during the ranging session;

receive, from the second UE based on the indication, the second set of displacements of the second UE or raw sensor information associated with the second set of displacements of the second UE;

compute a relative location of the second UE with respect to the first UE based on (1) the first set of displacements, (2) the second set of displacements or the raw sensor information associated with the second set of displacements, and (3) a set of ranging measurements associated with the ranging session;

estimate an accuracy for the computed relative location of the second UE; and

output the computed relative location of the second UE if the estimated accuracy exceeds an accuracy threshold, or request a user of the first UE to move or continue moving if the estimated accuracy is below the accuracy threshold.

2 . The apparatus of claim 1 , wherein the at least one processor, individually or in any combination, is further configured to:

initiate the ranging session for the computation of the relative location of the second UE.

3 . The apparatus of claim 1 , wherein the at least one processor, individually or in any combination, is further configured to:

perform the set of ranging measurements using at least one of:

ultrawide band (UWB) ranging,

Wi-Fi® ranging, or

Bluetooth® channel sounding (BT CS).

4 . The apparatus of claim 1 , wherein the set of ranging measurements corresponds to a set of time-related measurements or a set of phase-related measurements for a set of signals transmitted between the first UE and the second UE periodically during the ranging session.

5 . The apparatus of claim 1 , wherein to compute the relative location of the second UE with respect to the first UE based on (1) the first set of displacements, (2) the second set of displacements or the raw sensor information associated with the second set of displacements, and (3) the set of ranging measurements associated with the ranging session, the at least one processor, individually or in any combination, is configured to:

estimate a position and an orientation of the second reference frame of the second UE based on (1) the first set of displacements, (2) the second set of displacements or the raw sensor information associated with the second set of displacements, and (3) the set of ranging measurements using a loss function; and

compute the relative location of the second UE with respect to the first UE based on the estimated position and the orientation of the second reference frame.

6 . The apparatus of claim 1 , wherein to output the computed relative location of the second UE, the at least one processor, individually or in any combination, is configured to:

display the relative location of the second UE via a screen or a display.

7 . The apparatus of claim 1 , wherein the at least one processor, individually or in any combination, is further configured to:

calculate a distance between the first UE and the second UE based on at least one of the computed relative location of the second UE or the set of ranging measurements; and

terminate the ranging session when the calculated distance is below a distance threshold.

8 . The apparatus of claim 1 , wherein to track the first set of displacements of the first UE relative to the first reference frame of the first UE, the at least one processor, individually or in any combination, is configured to:

track the first set of displacements of the first UE relative to the first reference frame of the first UE while the first UE is in mobility.

9 . The apparatus of claim 1 , wherein the at least one processor, individually or in any combination, is further configured to:

detect that the second UE is in mobility, wherein the transmission of the indication is based on the detection that the second UE is in mobility.

10 . The apparatus of claim 1 , wherein to track the first set of displacements of the first UE, the at least one processor, individually or in any combination, is configured to:

track the first set of displacements of the first UE using at least one of a camera or an inertial measurement unit (IMU).

11 . The apparatus of claim 1 , wherein the first reference frame is different from the second reference frame.

12 . The apparatus of claim 1 , wherein the first UE is a single-antenna UE or is configured to use one antenna in multiple antennas for the ranging session.

13 . The apparatus of claim 1 , wherein information associated with the second reference frame of the second UE is below a certainty threshold or unavailable at the first UE prior to the transmission of the indication.

14 . The apparatus of claim 1 , wherein the at least one processor, individually or in any combination, is further configured to:

output an indication of the computed relative location of the second UE with respect to the first UE.

15 . The apparatus of claim 14 , wherein to output the indication of the computed relative location of the second UE with respect to the first UE, the at least one processor, individually or in any combination, is configured to:

transmit the indication of the computed relative location of the second UE with respect to the first UE;

display the indication via a screen, or

store the indication of the computed relative location of the second UE with respect to the first UE.

16 . The apparatus of claim 1 , further comprising a user interface (UI), wherein the at least one processor, individually or in any combination, is further configured to:

provide, at the UI, at least one of (1) a first guidance for moving the first UE, or (2) a second guidance for moving the first UE towards a direction.

17 . The apparatus of claim 16 , wherein the UI comprises a graphical user interface (GUI) configured to display a first graphical icon that is configured to move as the first UE is moved.

18 . A method of wireless communication at a first user equipment (UE), comprising:

tracking a first set of displacements of the first UE relative to a first reference frame of the first UE during a ranging session;

transmitting, to a second UE, an indication to track a second set of displacements of the second UE relative to a second reference frame of the second UE during the ranging session;

receiving, from the second UE based on the indication, the second set of displacements of the second UE or raw sensor information associated with the second set of displacements of the second UE;

computing a relative location of the second UE with respect to the first UE based on (1) the first set of displacements, (2) the second set of displacements or the raw sensor information associated with the second set of displacements, and (3) a set of ranging measurements associated with the ranging session;

estimate an accuracy for the computed relative location of the second UE; and

output the computed relative location of the second UE if the estimated accuracy exceeds an accuracy threshold, or request a user of the first UE to move or continue moving if the estimated accuracy is below the accuracy threshold.

19 . An apparatus for wireless communication at a first user equipment (UE), comprising:

a user interface (UI);

at least one memory; and

at least one processor coupled to the at least one memory, the at least one processor, individually or in any combination, is configured to:

provide, at the UI, a guidance for moving the first UE during a ranging session;

track a first set of displacements of the first UE relative to a first reference frame of the first UE when the UE is moving;

transmit, to a second UE, an indication to track a second set of displacements of the second UE relative to a second reference frame of the second UE during the ranging session;

receive, from the second UE based on the indication, the second set of displacements of the second UE or raw sensor information associated with the second set of displacements of the second UE;

compute a relative location of the second UE with respect to the first UE based on (1) the first set of displacements, (2) the second set of displacements or the raw sensor information associated with the second set of displacements, and (3) a set of ranging measurements associated with the ranging session;

estimate an accuracy for the computed relative location of the second UE; and

output the computed relative location of the second UE if the estimated accuracy exceeds an accuracy threshold, or request a user of the first UE to move or continue moving if the estimated accuracy is below the accuracy threshold.