Connection establishment for layer 2 UE-to-network relay
A method of connection establishment through a relay UE for a remote UE is proposed. The remote and relay UEs first perform discovery and establish a PC5 radio resource control (PC5-RRC) connection. Upon receiving a request from the remote UE, the relay UE and a serving gNB perform a relaying procedure for establishment of the remote UE's signalling radio bearer 1 (SRB1). The relay UE configures PC5 RLC channels for relaying of SRB1 towards the remote UE. The remote UE then enters an RRC_CONNECTED state. The remote UE and gNB establish security. The gNB configures additional data radio bearers (DRBs) for relaying. The relay UE configures PC5 RLC channels for relaying of the additional DRBs towards the remote UE. The DRBs can then be used for exchange of data between the remote UE and the gNB.
1. A method of connection establishment operable by a relay User Equipment (UE), comprising:
receiving, from a remote UE in an idle state of a protocol, a setup request message for a network node;
sending, to the network node, an information message comprising an indication that the remote UE requests relaying for the network node, wherein the information message is UEAssistanceInformation (UAI) message or a SidelinkUEInformation (SUI) message, and wherein the indication comprises an identity of the remote UE;
receiving, from the network node, a first configuration message comprising a sidelink configuration for a signalling radio bearer (SRB);
sending, to the remote UE, a second configuration message comprising a configuration of a radio link control (RLC) channel for the SRB;
receiving, from the remote UE, a first completion message in response to the second configuration message;
sending, to the network node, a second completion message responsive to the first configuration message;
receiving, from the remote UE, a setup complete message for the network node using the configuration of the RLC channel for the SRB; and
sending, to the network node, the setup complete message for the network node, wherein the setup complete message indicates that the remote UE enters a connected state of the protocol.
2. The method of claim 1 , further comprising:
receiving, from the network node, a third configuration message comprising a sidelink configuration for one or more data radio bearers (DRBs);
sending, to the remote UE, a fourth configuration message comprising a configuration of one or more RLC channels for the one or more DRBs;
receiving, from the remote UE, a third completion message in response to the fourth configuration message; and
sending, to the network node, a fourth completion message in response to the third configuration message.
3. The method of claim 2 , further comprising:
receiving, from the network node, a message for the remote UE on the SRB; and
transmitting, to the remote UE, the message for the remote UE on the RLC channel for the SRB.
4. The method of claim 2 , further comprising:
receiving, from the remote UE, a message for the network node on the RLC channel for the SRB; and
transmitting, to the network node, the message for the network node on the SRB.
5. The method of claim 2 , further comprising:
receiving, from the network node, a transmission for the remote UE on one of the one or more DRBs; and
transmitting, to the remote UE, the transmission for the remote UE on one of the one or more RLC channels for the one or more DRBs.
6. The method of claim 5 , wherein the one of the one or more RLC channels is determined by a mapping from the one of the one or more DRBs.
7. The method of claim 2 , further comprising:
receiving, from the remote UE, a transmission for the network node on one of the one or more RLC channels for the one or more DRBs; and
transmitting, to the network node, the transmission for the network node on one of the one or more DRBs of the remote UE.
8. The method of claim 7 , wherein the one of the one or more DRBs is determined by a mapping from the one of the one or more RLC channels.
9. A relay user equipment (UE), comprising:
a receiver that receives, from a remote UE in an idle state of a protocol, a setup request message for a network node;
a transmitter that transmits, to the network node, an information message comprising an indication that the remote UE requests relaying for the network node, wherein the information message is UEAssistanceInformation (UAI) message or a SidelinkUEInformation (SUI) message, and wherein the indication comprises an identity of the remote UE;
the receiver that receives, from the network node, a first configuration message comprising a sidelink configuration for a signalling radio bearer (SRB);
the transmitter that transmits, to the remote UE, a second configuration message comprising a configuration of a radio link control (RLC) channel for the SRB;
the receiver that receives, from the remote UE, a first completion message in response to the second configuration message;
the transmitter that transmits, to the network node, a second completion message responsive to the first configuration message;
the receiver that receives, from the remote UE, a setup complete message for the network node using the configuration of the RLC channel for the SRB; and
the transmitter that transmits, to the network node, the setup complete message for the network node, wherein the setup complete message indicates that the remote UE enters a connected state of the protocol.
10. The relay UE of claim 9 , further comprising:
the receiver that receives, from the network node, a third configuration message comprising a sidelink configuration for one or more data radio bearers (DRBs);
the transmitter that transmits, to the remote UE, a fourth configuration message comprising a configuration of one or more RLC channels for the one or more DRBs;
the receiver that receives, from the remote UE, a third completion message in response to the fourth configuration message; and
the transmitter that transmits, to the network node, a fourth completion message in response to the third configuration message.
11. The relay UE of claim 10 , further comprising:
the receiver that receives, from the network node, a message for the remote UE on the SRB; and
the transmitter that transmits, to the remote UE, the message for the remote UE on the RLC channel for the SRB.
12. The relay UE of claim 10 , further comprising:
the receiver that receives, from the remote UE, a message for the network node on the RLC channel for the SRB; and
the transmitter that transmits, to the network node, the message for the network node on the SRB.
13. The relay UE of claim 10 , further comprising:
the receiver that receives, from the network node, a transmission for the remote UE on one of the one or more DRBs; and
the transmitter that transmits, to the remote UE, the transmission for the remote UE on one of the one or more RLC channels for the one or more DRBs.
14. The relay UE of claim 13 , wherein the one of the one or more RLC channels is determined by a mapping from the one of the one or more DRBs.
15. The relay UE of claim 10 , further comprising:
the receiver that receives, from the remote UE, a transmission for the network node on one of the one or more RCL channels for the one or more DRBs; and
the transmitter that transmits, to the network node, the transmission for the network node on one of the one or more DRBs.
16. The relay UE of claim 15 , wherein the one of the one or more DRBs is determined by a mapping from the one of the one or more RLC channels.
17. A method of connection establishment operable by a remote User Equipment (UE), comprising:
sending, to a relay UE, a setup request message for a network node, wherein the setup request message uses a predefined configuration of a layer 2 protocol;
receiving, from the relay UE, a first configuration message comprising a configuration for a first relaying radio link control (RLC) channel for a signaling radio bearer (SRB), wherein the first configuration message is contained in a setup message from the network node in response to the relay UE sending an information message comprising an indication that the remote UE requests relaying for the network node, and wherein the information message is a UEAssistanceInformation (UAI) message or a SidelinkUEInformation (SUI) message, and wherein the indication comprises an identity of the remote UE;
sending, to the relay UE in response to the first configuration message, a first completion message;
receiving, from the relay UE, a setup message from the network node;
sending, to the relay UE, a setup completion message for the network node; and
entering a connected state of the protocol.
18. The method of claim 17 , further comprising:
establishing security with the network node;
receiving, from the relay UE, a second configuration message comprising configuration information for one or more RLC channels for one or more data radio bearers (DRBs);
sending, to the relay UE in response to the second configuration message, a second completion message;
receiving, from the relay UE, a third configuration message from the network node, comprising configuration information for the one or more DRBs; and
sending, to the relay UE in response to the third configuration message, a third completion message for the network node.
19. The method of claim 17 , wherein the establishing security comprises:
receiving, from the relay UE, a security command message from the network node;
applying a security configuration defined by the security command message; and
sending, to the relay UE, a security complete message for the network node.
20. The method of claim 17 , further comprising:
performing a discovery procedure with the relay UE, wherein the discovery procedure comprises sending, to the relay UE, a paging identifier of the remote UE).