Method and apparatus for triggering radio bearer release by a relay UE (user equipment) in a wireless communication system
A method and apparatus for triggering radio bearer release by a relay UE in a wireless communication system are disclosed. In one embodiment, the method includes the relay UE connects with an eNB. The method also includes the relay UE establishes a PDN connection for supporting traffic relaying. The method further includes the relay UE establishes a layer-2 link with a remote UE. In addition, the method includes the relay UE creates a radio bearer between the relay UE and the eNB for forwarding data packets between the remote UE and a PDN corresponding to the PDN connection. Furthermore, the method includes the relay UE sends a NAS message to the eNB if a failure of the layer-2 link is detected. And the method includes the relay UE receives a RRC message indicating release of the radio bearer in response to transmission of the NAS message from the eNB.
1. A method for triggering radio bearer release by a relay user equipment (UE), comprising:
the relay UE connects with an evolved Node-B (eNB);
the relay UE establishes a Packet Data Network (PDN) connection for supporting traffic relaying;
the relay UE establishes a layer-2 link with a remote UE;
the relay UE creates a radio bearer between the relay UE and the eNB for forwarding data packets between the remote UE and a PDN corresponding to the PDN connection; and
the relay UE sends a non-access stratum (NAS) message to the eNB if a failure of the layer-2 link is detected, wherein the NAS message is used to trigger release of a dedicated Evolved Packet System (EPS) bearer mapped to the radio bearer.
2. The method of claim 1 , wherein the PDN connection is established between the relay UE and a PDN gateway (PDN GW).
3. The method of claim 1 , wherein the layer-2 link is identified by a combination of a layer-2 identity of the relay UE and a layer-2 identity of the remote UE.
4. The method of claim 3 , wherein the layer-2 identity of the relay UE is a ProSe (Proximity-based Service) Relay UE identity.
5. The method of claim 4 , wherein the ProSe Relay UE identity is associated with a Relay Service Code.
6. The method of claim 5 , wherein the Relay Service Code identifies a connectivity service the relay UE provides to the remote UE, and the Relay Service Code is associated with the PDN connection.
7. The method of claim 1 , wherein the relay UE releases the radio bear before sending the NAS message, or releases the radio bear after sending the NAS message and receiving a Radio Resource Control (RRC) message indicating release of the radio bearer in response to transmission of the NAS message from the eNB.
8. The method of claim 1 , wherein the relay UE creates the radio bearer after receiving a Radio Resource Control (RRC) message including configuration of the radio bearer from the eNB.
9. The method of claim 1 , wherein the failure of the layer-2 link means layer-2 link maintenance over PC 5 procedure in the relay UE considers the remote UE is not in ProSe (Proximity-based Service) communication range of the relay UE.
10. A relay User Equipment (UE) for triggering radio bearer, comprising:
a control circuit;
a processor installed in the control circuit; and
a memory installed in the control circuit and operatively coupled to the processor;
wherein the processor is configured to execute a program code stored in the memory to enable the relay UE to:
connect with an evolved Node-B (eNB);
establish a Packet Data Network (PDN) connection for supporting traffic relaying;
establish a layer-2 link with a remote UE;
create a radio bearer between the relay UE and the eNB for forwarding data packets between the remote UE and a PDN corresponding to the PDN connection; and
send a non-access stratum (NAS) message to the eNB if a failure of the layer-2 link is detected, wherein the NAS message is used to trigger release of a dedicated Evolved Packet System (EPS) bearer mapped to the radio bearer.
11. The relay UE of claim 10 , wherein the PDN connection is established between the relay UE and a PDN gateway (PDN GW).
12. The relay UE of claim 10 , wherein the layer-2 link is identified by a combination of a layer-2 identity of the relay UE and a layer-2 identity of the remote UE.
13. The relay UE of claim 12 , wherein the layer-2 identity of the relay UE is a ProSe (Proximity-based Service) Relay UE identity.
14. The relay UE of claim 13 , wherein the ProSe Relay UE identity is associated with a Relay Service Code.
15. The relay UE of claim 14 , wherein the Relay Service Code identifies a connectivity service the relay UE provides to the remote UE, and the Relay Service Code is associated with the PDN connection.
16. The relay UE of claim 10 , wherein the relay UE releases the radio bear before sending the NAS message, or releases the radio bear after sending the NAS message and receiving a Radio Resource Control (RRC) message indicating release of the radio bearer in response to transmission of the NAS message from the eNB.
17. The relay UE of claim 10 , wherein the relay UE creates the radio bearer after receiving a Radio Resource Control (RRC) message including configuration of the radio bearer from the eNB.
18. The relay UE of claim 10 , wherein the failure of the layer-2 link means layer-2 link maintenance over PC 5 procedure in the relay UE considers the remote UE is not in ProSe (Proximity-based Service) communication range of the relay UE.