Radio resource control connection procedures for remote wireless devices
This disclosure relates to techniques for performing radio resource control procedures for remote wireless devices in a wireless communication system. A remote wireless device may transmit a radio resource control message that includes information configured to be relayed to a cellular base station to a relay wireless device, which may relay the information to the cellular base station. The cellular base station may also transmit a radio resource control message that includes information configured to be relayed to the remote wireless device to the relay wireless device, which may relay the information to the remote wireless device.
1. A method, comprising:
by a relay wireless device:
relaying radio resource control (RRC) messages between a cellular base station and a remote wireless device to establish an RRC connection with the cellular base station;
determining a radio link failure in a Uu link; and
transmitting an indication to the remote wireless device of the radio link failure in the Uu link to cause the remote wireless device to perform link selection.
2. The method of claim 1 , further comprising:
transmitting a discovery broadcast message indicating that the relay wireless device supports relaying RRC messages;
wherein the RRC connection is established based at least in part in response to the discovery broadcast message.
3. The method of claim 1 , further comprising:
stopping transmission of discovery broadcast messages to the remote wireless device based at least in part on the radio link failure of the Uu link.
4. The method of claim 1 , wherein the indication of the radio link failure in the Uu link comprises one or more of:
an indication that the radio link failure in the Uu link has occurred;
an indication to suspend a wireless link between the relay wireless device and the remote wireless device; or
an indication to release the wireless link between the relay wireless device and the remote wireless device.
5. The method of claim 1 , further comprising:
providing a second indication of the radio link failure of the Uu link to the cellular base station.
6. The method of claim 5 , further comprising:
receiving an indication to release the remote wireless device from the cellular base station in response to the second indication of the radio link failure of the Uu link.
7. The method of claim 1 , further comprising:
receiving an RRC re-establishment request from the remote UE; and
relaying the RRC re-establishment request to the cellular base station, wherein the RRC re-establishment request is relayed to the cellular base station with an identifier of the remote UE.
8. An apparatus, comprising:
a processor configured to cause a relay wireless device to:
relay radio resource control (RRC) messages between a cellular base station and a remote wireless device to establish an RRC connection with the cellular base station;
determine a radio link failure in a Uu link; and
transmit an indication to the remote wireless device of the radio link failure in the Uu link to cause the remote wireless device to perform radio resource control re-establishment.
9. The apparatus of claim 8 , wherein the processor is further configured to cause the relay wireless device to:
transmit a discovery broadcast message indicating that the relay wireless device supports relaying RRC messages;
wherein the RRC connection is established based at least in part in response to the discovery broadcast message.
10. The apparatus of claim 8 , wherein the processor is further configured to cause the relay wireless device to:
stop transmission of discovery broadcast messages to the remote wireless device based at least in part on the radio link failure of the Uu link.
11. The apparatus of claim 8 , wherein the indication of the radio link failure in the Uu link comprises one or more of:
an indication that the radio link failure in the Uu link has occurred;
an indication to suspend a wireless link between the relay wireless device and the remote wireless device; or
an indication to release the wireless link between the relay wireless device and the remote wireless device.
12. The apparatus of claim 8 , wherein the processor is further configured to cause the relay wireless device to:
provide a second indication of the radio link failure of the Uu link to the cellular base station.
13. The apparatus of claim 12 , wherein the processor is further configured to cause the relay wireless device to:
receive an indication to release the remote wireless device from the cellular base station in response to the second indication of the radio link failure of the Uu link.
14. The apparatus of claim 8 , wherein the processor is further configured to cause the relay wireless device to:
receive an RRC re-establishment request from the remote UE; and
relay the RRC re-establishment request to the cellular base station, wherein the RRC re-establishment request is relayed to the cellular base station with an identifier of the remote UE.
15. An apparatus, comprising:
a processor configured to cause a remote wireless device to:
exchange radio resource control (RRC) messages with a cellular base station via a relay wireless device to establish an RRC connection with the cellular base station, wherein the relay wireless device and the cellular base station are connected by a Uu link;
receive an indication from the relay wireless device of a radio link failure in the Uu link; and
in response to the indication, perform link selection or transmit an RRC re-establishment request.
16. The remote wireless device of claim 15 , wherein the remote wireless device is further configured to:
receive a discovery broadcast message from the relay wireless device indicating that the relay wireless device supports relaying RRC messages;
wherein the RRC messages are exchanged with the cellular base station at least in part in response to the discovery broadcast message.
17. The remote wireless device of claim 15 , wherein the indication of the radio link failure in the Uu link comprises one or more of:
an indication that the radio link failure in the Uu link has occurred;
an indication to suspend a wireless link between the relay wireless device and the remote wireless device; or
an indication to release the wireless link between the relay wireless device and the remote wireless device.
18. The remote wireless device of claim 15 , wherein the remote wireless device is further configured to:
perform link reselection responsive to receiving the indication of the radio link failure in the Uu link.
19. The remote wireless device of claim 18 ,
wherein the RRC re-establishment request is transmitted to the relay or another wireless device depending on a result of the link reselection.
20. The remote wireless device of claim 15 ,
wherein the cellular base station comprises a 5th Generation New Radio (5G NR) gNodeB (gNB).