Accurate sidelink positioning reference signal transmission timing
According to embodiments of the present disclosure, a PRS transmission timing scheme for sidelink assisted positioning is proposed. According to embodiments of the present disclosure, the supporting terminal device measures a receiving-transmitting (Rx-Tx) time difference between receiving the downlink PRS (DL) and transmitting the sidelink (SL) PRS. The supporting terminal device transmits an indication of the RX-TX time difference to the location management device in order to reduce the impact of low synchronization issue on positioning performance as well as the use of wideband PRS for higher measurement accuracy. In this way, the positioning performance of sidelink assisted positioning has been improved.
1 . A method comprising:
transmitting, at a second device and to a first device, a configuration for transmitting a sidelink positioning reference signal;
receiving an indication of a time difference measured with the first device, the time difference being between a reception of a downlink positioning reference signal with the first device and a transmission of the sidelink positioning reference signal with the first device;
receiving an indication of a reference signal time difference from a fourth device, the reference signal time difference being between a reception of the downlink positioning reference signal with the fourth device and a reception of the sidelink positioning reference signal with the fourth device; and
determining an estimated position of the fourth device based at least in part on the time difference and the reference signal time difference.
2 . The method of claim 1 , wherein transmitting the configuration for transmitting the sidelink positioning reference signal comprises:
determining a synchronization level between the first device and a third device or between the third device and at least a fifth device; and
in accordance with a determination that the synchronization level exceeds a threshold level, transmitting the configuration to the first device.
3 . The method of claim 1 , wherein the receiving of the indication of the time difference comprises receiving the indication of the time difference from the fourth device.
4 . The method of claim 1 , further comprising:
receiving an indication of a further time difference measured with a third device, the further time difference being between a transmission of the downlink positioning reference signal with the third device and a reception of the sidelink positioning reference signal with the third device;
determining a propagation delay estimate between the first device and the third device based on the time difference and the further time difference; and
updating a synchronization between the first device and the third device based on the time difference and the propagation delay estimate.
5 . The method of claim 1 , wherein determining the estimated position of the fourth device comprises:
updating the reference signal time difference with the time difference.
6 . The method of claim 1 , further comprising:
receiving an indication of a further reference signal time difference measured with the first device based on at least a reception of the downlink positioning reference signal; and
determining an estimated position of the first device based on the further reference signal time difference.
7 . The method of claim 1 , wherein the first device comprises a terminal device, a second device comprises a location management function device, a third device comprises a network device, the fourth device comprises a further terminal device and a fifth device comprises a further network device.
8 . A second device comprising:
at least one processor; and
at least one non-transitory memory including computer program codes;
the at least one memory and the computer program codes are configured to, with the at least one processor, cause the second device to perform:
transmit to a first device, a configuration for transmitting a sidelink positioning reference signal;
receive an indication of a time difference measured with the first device, the time difference being between a reception of a downlink positioning reference signal with the first device and a transmission of the sidelink positioning reference signal with the first device;
receive an indication of a reference signal time difference from a fourth device, the reference signal time difference being between a reception of the downlink positioning reference signal with the fourth device and a reception of the sidelink positioning reference signal with the fourth device; and
determine an estimated position of the fourth device based at least in part on the time difference and the reference signal time difference.
9 . A non-transitory computer readable storage medium comprising program instructions stored thereon, the instructions, when executed by an apparatus, causing the apparatus to perform the method of claim 1 .