Improving sidelink positioning via messaging between wireless nodes
Certain aspects of the present disclosure provide techniques for improving sidelink positioning via messaging between wireless nodes, e.g., roadside service units (RSUs). A method that may be performed by a user equipment (UE) includes receiving a first positioning reference signal (PRS) from a first wireless node, receiving a second PRS from a second wireless node, receiving, from the first wireless node, an estimate of a first clock error component between the first wireless node and the second wireless node, and estimating a position of the UE, based on the first PRS, the second PRS, and the estimate of the first clock error component.
1. A method for wireless communications performed by a first wireless node, comprising:
transmitting a first positioning reference signal (PRS) at a first time;
receiving a second PRS from a second wireless node at a second time;
receiving, from the second wireless node, a first message indicating a third time when the second wireless node received the first PRS and a fourth time when the second wireless node transmitted the second PRS;
estimating a clock error component between the first wireless node and the second wireless node, using the first time, the second time, the third time, and the fourth time; and
transmitting, to a user equipment (UE), a second message indicating the clock error component.
2. The method of claim 1 , wherein the second message further indicates the first time.
3. The method of claim 1 , wherein:
the first message comprises an intelligent transportation system (ITS) message; and
the second message comprises another ITS message.
4. The method of claim 1 , further comprising:
obtaining a trigger from the UE to transmit the clock error component to the UE; and
wherein transmitting the second message indicating the clock error component is in accordance with the trigger.
5. The method of claim 1 , wherein at least one of the first wireless node or the second wireless node comprises a roadside service unit (RSU).
6. The method of claim 1 , wherein the first wireless node is a master wireless node among multiple wireless nodes.
7. The method of claim 6 , further comprising:
receiving estimates of a clock error component for each node pair of the multiple wireless nodes; and
wherein the second message is transmitted to the UE and further indicates the estimates of the clock error component for each node pair.
8. The method of claim 1 , wherein in response to the first wireless node and the second wireless node comprising a node pair among multiple wireless nodes, the second message is transmitted to a master node or to the UE; and in response to the first wireless node and the second wireless node not comprising a node pair among multiple wireless nodes, transmitting the second message to the UE.
9. An apparatus for wireless communications performed by a first wireless node, comprising:
memory;
a transceiver; and
at least one processor, the at least one processor communicatively connected to the memory and the transceiver, the at least one processor configured to:
transmit a first positioning reference signal (PRS) at a first time;
receive a second PRS from a second wireless node at a second time;
receive, from the second wireless node, a first message indicating a third time when the second wireless node received the first PRS and a fourth time when the second wireless node transmitted the second PRS;
estimate a clock error component between the apparatus and the second wireless node, using the first time, the second time, the third time, and the fourth time; and
transmit, to a user equipment (UE), a second message indicating the clock error component.
10. The apparatus of claim 9 , wherein the second message further indicates the first time.
11. The apparatus of claim 9 , wherein:
the first message comprises an intelligent transportation system (ITS) message; and
the second message comprises another ITS message.
12. The apparatus of claim 9 , wherein the at least one processor is further configured to:
obtain a trigger from the UE to transmit the clock error component to the UE; and
wherein transmitting the second message indicating the clock error component is in accordance with the trigger.
13. The apparatus of claim 9 , wherein at least one of the first wireless node or the second wireless node comprises a roadside service unit (RSU).
14. The apparatus of claim 9 , wherein the first wireless node is a master wireless node among multiple wireless nodes.
15. The apparatus of claim 14 , wherein the at least one processor is further configured to cause the apparatus to:
receive estimates of a clock error component for each node pair of the multiple wireless nodes; and
wherein the second message is transmitted to the UE and further indicates the estimates of the clock error component for each node pair.
16. The apparatus of claim 9 , wherein in response to the first wireless node and the second wireless node comprising a node pair among multiple wireless nodes, the second message is transmitted to a master node or to the UE; and in response to the first wireless node and the second wireless node not comprising a node pair among multiple wireless nodes, transmitting the second message to the UE.