UE initiated propagation delay compensation mechanism

1. A method comprising:

receiving a configuration to provide a propagation delay notification for a propagation delay estimation;

wherein the configuration to provide the propagation delay notification comprises a propagation delay threshold used to determine whether to provide the propagation delay notification;

determining when the notification should be transmitted;

transmitting the propagation delay notification;

providing the propagation delay notification in response to a current propagation delay estimation being greater than a difference between a previously provided propagation delay estimation and the propagation delay threshold; and

determining a corresponding action based on the configuration of a relation between uplink reference signals and downlink reference signals.

2. The method of claim 1 , further comprising transmitting an uplink reference signal to activate the propagation delay estimation.

3. The method of claim 1 , further comprising applying the propagation delay estimation to synchronize a time of day of a user equipment.

4. The method of claim 1 , further comprising:

in response to at least one downlink reference signal not being configured, receiving a timing adjustment message for the propagation delay estimation.

5. The method of claim 1 , further comprising:

in response to at least one downlink reference signal being configured, performing a user equipment reception and transmission timing difference measurement, and either signaling the user equipment reception and transmission timing difference measurement or receiving a radio node reception and transmission timing difference measurement for the propagation delay estimation.

6. The method of claim 5 , further comprising:

receiving a configuration of the relation between uplink reference signals and downlink reference signals as an index;

determining the at least one downlink reference signal to use using the index; and

transmitting the uplink reference signal to activate the propagation delay estimation based on the determined at least one downlink reference signal.

7. The method of claim 1 , wherein the propagation delay notification comprises at least one burst request and/or a desired periodicity.

8. The method of claim 7 , wherein the RTT is a multi-RTT with measurements from neighboring cells.

9. The method of claim 1 , further comprising:

selecting the propagation delay estimate when multiple propagation delay estimates are available;

wherein the multiple propagation delay estimates comprise a reception/transmission measurement and/or a timing advance.

10. The method of claim 1 , further comprising estimating the propagation delay as a round trip time (RTT).

11. The method of claim 1 , wherein:

the user equipment is idle or inactive; and

the propagation delay notification is provided in response to a reference signal time difference changing more than a threshold.

12. The method of claim 1 , wherein the propagation delay notification is a multi-bit notification comprising an expected accuracy or an expected periodicity of measurement updates.

13. A method comprising:

providing a configuration to provide a propagation delay notification for a propagation delay estimation;

wherein providing the configuration to provide the propagation delay notification comprises providing a propagation delay threshold; and

receiving the propagation delay notification;

wherein the propagation delay notification is received in response to a current propagation delay estimation being greater than a difference between a previously provided propagation delay estimation and the propagation delay threshold;

wherein the configuration comprises a relation between uplink reference signals and downlink reference signals.

14. The method of claim 13 , further comprising receiving an uplink reference signal to activate the propagation delay estimation.

15. The method of claim 13 , wherein the estimated propagation delay is applied to synchronize a time of day.

16. The method of claim 13 , further comprising:

in response to at least one downlink reference signal not being configured, providing a timing adjustment message for the propagation delay estimation.

17. The method of claim 13 , further comprising:

in response to at least one downlink reference signal being configured, performing a radio node reception and transmission timing difference measurement, and either signaling the radio node reception and transmission timing difference measurement or receiving a different reception and transmission timing difference measurement for the propagation delay estimation.

18. The method of claim 13 , further comprising:

transmitting the configuration of the relation between the uplink reference signals and downlink reference signals as an index; and

receiving the uplink reference signal to activate the propagation delay estimation based on the index.

19. The method of claim 13 , further comprising:

determining the propagation delay threshold based on at least one of: an accuracy budget; and/or mobility event statistics.

20. The method of claim 13 , further comprising:

determining whether to provide the configuration to provide the propagation delay notification for the propagation delay estimation or to transmit an uplink reference signal configuration for the propagation delay estimation;

wherein the determining is based on at least one of: a time synchronization accuracy requirement, device capabilities, mobility events or a timer expiry.

21. The method of claim 13 , wherein the propagation delay notification comprises at least one burst request and/or a desired periodicity.

22. The method of claim 13 , further comprising transmitting the propagation delay estimation.

23. The method of claim 13 , further comprising estimating the propagation delay as a round trip time (RTT).

24. The method of claim 23 , wherein the RTT is a multi-RTT with measurements from neighboring cells.

25. The method of claim 13 , further comprising broadcasting the propagation delay estimation.

26. The method of claim 13 , wherein:

the propagation delay notification is received in response to a reference signal time difference changing more than a threshold.

27. The method of claim 13 , wherein the propagation delay notification is a multi-bit notification comprising an expected accuracy or an expected periodicity of measurement updates.

28. An apparatus comprising:

at least one processor; and

at least one non-transitory memory including computer program code;

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:

receive a configuration to provide a propagation delay notification for a propagation delay estimation;

wherein the configuration to provide the propagation delay notification comprises a propagation delay threshold used to determine whether to provide the propagation delay notification;

determine when the notification should be transmitted;

transmit the propagation delay notification;

provide the propagation delay notification in response to a current propagation delay estimation being greater than a difference between a previously provided propagation delay estimation and the propagation delay threshold; and

determine a corresponding action based on the configuration of a relation between uplink reference signals and downlink reference signals.

29. A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable with the machine for performing operations, the operations comprising:

receiving a configuration to provide a propagation delay notification for a propagation delay estimation;

wherein the configuration to provide the propagation delay notification comprises a propagation delay threshold used to determine whether to provide the propagation delay notification;

determining when the notification should be transmitted;

transmitting the propagation delay notification;

providing the propagation delay notification in response to a current propagation delay estimation being greater than a difference between a previously provided propagation delay estimation and the propagation delay threshold; and

determining a corresponding action based on the configuration of a relation between uplink reference signals and downlink reference signals.

30. A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable with the machine for performing operations, the operations comprising:

providing a configuration to provide a propagation delay notification for a propagation delay estimation;

wherein providing the configuration to provide the propagation delay notification comprises providing a propagation delay threshold; and

receiving the propagation delay notification;

wherein the propagation delay notification is received in response to a current propagation delay estimation being greater than a difference between a previously provided propagation delay estimation and the propagation delay threshold;

wherein the configuration comprises a relation between uplink reference signals and downlink reference signals.

31. An apparatus comprising:

at least one processor; and

at least one non-transitory memory including computer program code;

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to:

provide a configuration to provide a propagation delay notification for a propagation delay estimation;

wherein providing the configuration to provide the propagation delay notification comprises providing a propagation delay threshold; and

receive the propagation delay notification;

wherein the propagation delay notification is received in response to a current propagation delay estimation being greater than a difference between a previously provided propagation delay estimation and the propagation delay threshold;

wherein the configuration comprises a relation between uplink reference signals and downlink reference signals.