Unicast link radio link failure detection and management

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

establishing a sidelink connection with a second UE, wherein the sidelink connection is associated with a plurality of flows;

determining, based at least in part on monitoring each flow of the plurality of flows, a radio link status of the sidelink connection;

transmitting, based on the determining, a non-access stratum layer message to the second UE based at least on the radio link status of the sidelink connection; and

transmitting a second message to the second UE reconfiguring one or more parameters of the sidelink connection, wherein reconfiguring the one or more parameters of the sidelink connection comprises reconfiguring the sidelink connection from a first configuration to a second configuration from a set of available configurations configured for the sidelink connection or reconfiguring one or more quality of service parameters configured for the sidelink connection.

2. The method of claim 1 , further comprising:

determining that no data is communicated across a first flow of the plurality of flows; and

transmitting the non-access stratum layer message to the second UE, wherein the non-access stratum layer message comprises a keep-alive message requesting confirmation from the second UE that the radio link status of the sidelink connection is active.

3. The method of claim 1 , further comprising:

receiving a response message from the second UE indicating that the radio link status of the sidelink connection with the second UE is active, wherein transmitting the second message to the second UE reconfiguring one or more parameters of the sidelink connection is based at least in part on receiving the response message.

4. The method of claim 1 , further comprising:

determining, based at least in part on a lack of a response message from the second UE, that the radio link status of the sidelink connection with the second UE comprises a radio link failure; and

performing, based at least in part on the radio link failure, a radio link failure recovery procedure to establish a second sidelink connection with the second UE.

5. The method of claim 2 , wherein determining that no data is communicated comprises:

determining that data communicated across the first flow fails to satisfy a quality of service requirement associated with the first flow.

6. The method of claim 2 , wherein determining that no data is communicated comprises:

determining that no data has been communicated across the first flow for a threshold time period associated with the first flow.

7. The method of claim 1 , further comprising:

determining that no data is communicated across a first flow of the plurality of flows;

determining that data is communicated across a second flow of the plurality of flows; and

determining that the radio link status of the sidelink connection comprises a degraded radio link status, wherein transmitting the second message to the second UE reconfiguring one or more parameters of the sidelink connection is based at least in part on the degraded radio link status.

8. The method of claim 1 , further comprising:

determining that the non-access stratum layer message was transmitted within a threshold time period; and

refraining from transmitting a second non-access stratum layer message to the second UE based at least on the non-access stratum layer message.

9. The method of claim 1 , wherein determining the radio link status of the sidelink connection comprises:

determining, for each flow of the plurality of flows, whether data communicated across each flow satisfies a quality of service requirement configured for the flow.

10. The method of claim 1 , wherein the non-access stratum layer message comprises a PC5 sidelink (PC5-S) message.

11. A method for wireless communication at a second user equipment (UE), comprising:

establishing a sidelink connection with a first UE, wherein the sidelink connection is associated with a plurality of flows;

receiving a non-access stratum layer message from the first UE indicating a radio link status of the sidelink connection, wherein the non-access stratum layer message is based at least in part on a status at the first UE of each flow of the plurality of flows;

transmitting a response message to the first UE indicating that the radio link status of the sidelink connection with the first UE is active;

receiving, based at least in part on the response message, a second message from the first UE reconfiguring one or more parameters of the sidelink connection; and

reconfiguring the one or more parameters of the sidelink connection based at least on part on the second message, wherein reconfiguring the one or more parameters of the sidelink connection comprises reconfiguring the sidelink connection from a first configuration to a second configuration from a set of available configurations configured for the sidelink connection or reconfiguring one or more quality of service parameters configured for the sidelink connection.

12. The method of claim 11 , wherein the non-access stratum layer message comprises a keep-alive message requesting confirmation from the second UE that the radio link status of the sidelink connection is active.

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

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

establish a sidelink connection with a second UE, wherein the sidelink connection is associated with a plurality of flows;

determine, based at least in part on monitoring each flow of the plurality of flows, a radio link status of the sidelink connection;

transmit, based on the determining, a non-access stratum layer message to the second UE based at least on the radio link status of the sidelink connection; and

transmit a second message to the second UE reconfiguring one or more parameters of the sidelink connection, wherein reconfiguring the one or more parameters of the sidelink connection comprises reconfiguring the sidelink connection from a first configuration to a second configuration from a set of available configurations configured for the sidelink connection or reconfiguring one or more quality of service parameters configured for the sidelink connection.

14. The apparatus of claim 13 , wherein the instructions are further executable by the processor to cause the apparatus to:

determine that no data is communicated across a first flow of the plurality of flows; and

transmit the non-access stratum layer message to the second UE, wherein the non-access stratum layer message comprises a keep-alive message requesting confirmation from the second UE that the radio link status of the sidelink connection is active.

15. The apparatus of claim 14 , wherein the instructions are further executable by the processor to cause the apparatus to:

receive a response message from the second UE indicating that the radio link status of the sidelink connection with the second UE is active, wherein transmitting the second message to the second UE reconfiguring one or more parameters of the sidelink connection is based at least in part on receiving the response message.

16. The apparatus of claim 14 , wherein the instructions are further executable by the processor to cause the apparatus to:

determine, based at least in part on a lack of a response message from the second UE, that the radio link status of the sidelink connection with the second UE comprises a radio link failure; and

perform, based at least in part on the radio link failure, a radio link failure recovery procedure to establish a second sidelink connection with the second UE.

17. The apparatus of claim 14 , wherein the instructions to determine that no data is communicated are executable by the processor to cause the apparatus to:

determine that data communicated across the first flow fails to satisfy a quality of service requirement associated with the first flow.

18. The apparatus of claim 14 , wherein the instructions to determine that no data is communicated are executable by the processor to cause the apparatus to:

determine that no data has been communicated across the first flow for a threshold time period associated with the first flow.

19. The apparatus of claim 13 , wherein the instructions are further executable by the processor to cause the apparatus to:

determine that no data is communicated across a first flow of the plurality of flows;

determine that data is communicated across a second flow of the plurality of flows; and

determine that the radio link status of the sidelink connection comprises a degraded radio link status, wherein transmitting the second message to the second UE reconfiguring one or more parameters of the sidelink connection is based at least in part on the degraded radio link status.

20. The apparatus of claim 13 , wherein the instructions are further executable by the processor to cause the apparatus to:

determine that the non-access stratum layer message was transmitted within a threshold time period; and

refrain from transmitting a second non-access stratum layer message to the second UE based at least on the non-access stratum layer message.

21. The apparatus of claim 13 , wherein the instructions to determine the radio link status of the sidelink connection are executable by the processor to cause the apparatus to:

determine, for each flow of the plurality of flows, whether data communicated across each flow satisfies a quality of service requirement configured for the flow.

22. The apparatus of claim 13 , wherein the non-access stratum layer message comprises a PC5 sidelink (PC5-S) message.

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

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

establish a sidelink connection with a first UE, wherein the sidelink connection is associated with a plurality of flows;

receive a non-access stratum layer message from the first UE indicating a radio link status of the sidelink connection, wherein the non-access stratum layer message is based at least in part on a status at the first UE of each flow of the plurality of flows;

transmit a response message to the first UE indicating that the radio link status of the sidelink connection with the first UE is active;

receive, based at least in part on the response message, a second message from the first UE reconfiguring one or more parameters of the sidelink connection; and

reconfigure the one or more parameters of the sidelink connection based at least on part on the second message, wherein reconfiguring the one or more parameters of the sidelink connection comprises reconfiguring the sidelink connection from a first configuration to a second configuration from a set of available configurations configured for the sidelink connection or reconfiguring one or more quality of service parameters configured for the sidelink connection.

24. The apparatus of claim 23 , wherein the non-access stratum layer message comprises a keep-alive message requesting confirmation from the second UE that the radio link status of the sidelink connection is active.