Integrated access and backhaul (IAB) timing handling for positioning
Disclosed are techniques for wireless communication. In an aspect, an integrated access and backhaul (IAB) node sets a downlink transmission timing of the IAB node relative to a downlink reception timing of the IAB node based on a first set of values for a set of timing parameters, receives, from a parent IAB node of the IAB node, a second set of values for the set of timing parameters, and transmits, to a positioning entity, a report indicating a change from the first set of values to the second set of values, a new downlink transmission timing based on the second set of values, or a change in downlink transmission timing.
1. An integrated access and backhaul (IAB) node, 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:
set a downlink transmission timing of the IAB node relative to a downlink reception timing of the IAB node based on a first set of values for a set of timing parameters;
receive, from a parent IAB node of the IAB node, a second set of values for the set of timing parameters;
cause the at least one transceiver to transmit, to a positioning entity after the second set of values from the parent IAB node is received by the IAB node, a report indicating the second set of values, a change from the first set of values to the second set of values, a new downlink transmission timing based on the second set of values, or a change in downlink transmission timing; and
cause the at least one transceiver to transmit, to a central unit (CU) for the IAB node, an indication of the change from the first set of values to the second set of values for the set of timing parameters to enable the CU to identify duplicate changes to the set of timing parameters for IAB nodes served by the CU.
2. The IAB node of claim 1 , wherein the set of timing parameters comprises a timing advance parameter, a T_delta parameter, or both.
3. The IAB node of claim 1 , wherein:
the positioning entity comprises a location server engaged in a positioning session with a UE, and
the location server forwards the report to the UE.
4. The IAB node of claim 3 , wherein a distributed unit (DU) of the IAB node causes the at least one transceiver to transmit the report to the location server over New Radio positioning protocol A (NRPPa).
5. The IAB node of claim 3 , wherein a mobile terminating (MT) function of the IAB node causes the at least one transceiver to transmit the report to the location server over a Long-Term Evolution positioning protocol (LPP).
6. The IAB node of claim 1 , wherein the positioning entity comprises a UE engaged in a UE-based positioning session with the IAB node.
7. The IAB node of claim 1 , wherein the at least one processor is further configured to:
cause the at least one transceiver to transmit, to each child node of the IAB node, an indication of the change from the first set of values to the second set of values for the set of timing parameters to prevent the child node from updating the set of timing parameters for the child node for up to a threshold period of time.
8. The IAB node of claim 7 , wherein the threshold period of time depends on a hop count from the IAB node to the child node.
9. The IAB node of claim 1 , wherein, based on the report not indicating a duplicate change to the set of timing parameters, the CU transmits the report to a location server and/or a UE involved in a positioning session with the IAB node.
10. The IAB node of claim 1 , wherein the IAB node comprises a base station.
11. The IAB node of claim 1 , wherein the IAB node is connected to the parent IAB node over a wireless backhaul link.
12. A method of wireless communication performed by an integrated access and backhaul (TAB) node, comprising:
setting a downlink transmission timing of the TAB node relative to a downlink reception timing of the TAB node based on a first set of values for a set of timing parameters;
receiving, from a parent TAB node of the TAB node, a second set of values for the set of timing parameters;
transmitting, to a positioning entity after the second set of values from the parent TAB node is received by the TAB node, a report indicating the second set of values or a change from the first set of values to the second set of values, a new downlink transmission timing based on the second set of values, or a change in downlink transmission timing; and
transmitting, to a central unit (CU) for the TAB node, an indication of the change from the first set of values to the second set of values for the set of timing parameters to enable the CU to identify duplicate changes to the set of timing parameters for TAB nodes served by the CU.
13. The method of claim 12 , wherein the set of timing parameters comprises a timing advance parameter, a T_delta parameter, or both.
14. The method of claim 12 , wherein:
the positioning entity comprises a location server engaged in a positioning session with a UE, and the method further comprising:
forwarding, by the location server, the report to the UE.
15. The method of claim 14 , wherein:
a distributed unit (DU) of the IAB node transmits the report to the location server over New Radio positioning protocol A (NRPPa), or
a mobile terminating (MT) function of the IAB node transmits the report to the location server over a Long-Term Evolution positioning protocol (LPP).
16. The method of claim 12 , wherein the positioning entity comprises a UE engaged in a UE-based positioning session with the IAB node.
17. The method of claim 12 , further comprising:
transmitting, to each child node of the IAB node, an indication of the change from the first set of values to the second set of values for the set of timing parameters to prevent the child node from updating the set of timing parameters for the child node for up to a threshold period of time.
18. The method of claim 12 , wherein:
the IAB node comprises a base station, and
the IAB node is connected to the parent IAB node over a wireless backhaul link.