Method and apparatus for removing SRAP header in a wireless communication system
A method and device for a UE-to-Network (U2N) Relay User Equipment (UE) are disclosed. In one embodiment, the U2N Relay UE establishes at least one PC5 connection (or PC5 unicast link) with at least one child UE and establishes a Radio Resource Control (RRC) connection with a network node. Furthermore, the U2N Relay UE receives a Sidelink Relay Adaptation Protocol (SRAP) Data Protocol Data Unit (PDU) on a Uu Relay Radio Link Control (RLC) Channel from the network node, wherein the SRAP Data PDU includes a header and a data field and wherein the header includes a BEARER identity (ID) field and a UE ID field.
1 . A method for a UE-to-Network (U2N) Relay User Equipment (UE), comprising:
the U2N Relay UE establishes at least one PC5 connection (or PC5 unicast link) with at least one child UE and establishes a Radio Resource Control (RRC) connection with a network node;
the U2N Relay UE receives a Sidelink Relay Adaptation Protocol (SRAP) Data Protocol Data Unit (PDU) on a Uu Relay Radio Link Control (RLC) Channel from the network node, wherein the SRAP Data PDU includes a header and a data field and wherein the header includes a BEARER identity (ID) field and a UE ID field; and
the U2N Relay UE determines to remove the header from the SRAP data PDU if the UE ID field matches a sl-LocalIdentity configured in a sl-SRAP-ConfigRelay, the BEARER ID field is 0, and a bearer indicated by the BEARER ID field is identified as Signalling Radio Bearer (SRB) based on a sl-Remote UE-RB-Identity associated with an entry containing the sl-EgressRLC-ChannelUu which matches a Logical Channel ID (LCID) of a Uu Relay RLC Channel from which the SRAP Data PDU is received.
2 . The method of claim 1 , wherein the sl-SRAP-ConfigRelay is included directly in a SL-Remote UE-ToAddMod.
3 . The method of claim 2 , wherein the SL-Remote UE-ToAddMod also includes a sl-L2IdentityRemote of a directly connected child UE.
4 . The method of claim 1 , wherein the sl-SRAP-ConfigRelay is not included in a SL-SRAP-ConfigRelay-ToAddMod or SL-SRAP-ConfigRelay-ToAddModList.
5 . The method of claim 4 , wherein the SL-SRAP-ConfigRelay-ToAddMod is included in the SL-SRAP-ConfigRelay-ToAddModList.
6 . The method of claim 5 , wherein the SL-SRAP-ConfigRelay-ToAddModList includes a list of SRAP configuration(s) for each indirectly connected child UE in multi-hop U2N Relay.
7 . The method of claim 1 , wherein the sl-SRAP-ConfigRelay is included in a RRCReconfiguration message received from the network node.
8 . The method of claim 1 , wherein the U2N Relay UE is a Last U2N Relay UE.
9 . The method of claim 1 , wherein the data field includes a RRCSetup message.
10 . The method of claim 1 , further comprising:
the U2N Relay UE submits the SRAP data PDU to a determined egress RLC channel of a determined egress link.
11 . A UE-to-Network (U2N) Relay User Equipment (UE), comprising:
a control circuit;
a processor installed in the control circuit;
a memory installed in the control circuit and coupled to the processor;
wherein the processor is configured to execute a program code stored in the memory to:
establish at least one PC5 connection (or PC5 unicast link) with at least one child UE and establishes a Radio Resource Control (RRC) connection with a network node;
receive a Sidelink Relay Adaptation Protocol (SRAP) Data Protocol Data Unit (PDU) on a Uu Relay Radio Link Control (RLC) Channel from the network node, wherein the SRAP Data PDU includes a header and a data field and wherein the header includes a BEARER identity (ID) field and a UE ID field; and
determine to remove the header from the SRAP data PDU if the UE ID field matches a sl-LocalIdentity configured in a sl-SRAP-ConfigRelay, the BEARER ID field is 0, and a bearer indicated by the BEARER ID field is identified as Signalling Radio Bearer (SRB) based on a sl-Remote UE-RB-Identity associated with an entry containing the sl-EgressRLC-ChannelUu which matches a Logical Channel ID (LCID) of a Uu Relay RLC Channel from which the SRAP Data PDU is received.
12 . The U2N Relay UE of claim 11 , wherein the sl-SRAP-ConfigRelay is included directly in a SL-Remote UE-ToAddMod.
13 . The U2N Relay UE of claim 12 , wherein the SL-Remote UE-ToAddMod also includes a sl-L2IdentityRemote of a directly connected child UE.
14 . The U2N Relay UE of claim 11 , wherein the sl-SRAP-ConfigRelay is not included in a SL-SRAP-ConfigRelay-ToAddMod or SL-SRAP-ConfigRelay-ToAddModList.
15 . The U2N Relay UE of claim 14 , wherein the SL-SRAP-ConfigRelay-ToAddMod is included in the SL-SRAP-ConfigRelay-ToAddModList.
16 . The U2N Relay UE of claim 15 , wherein the SL-SRAP-ConfigRelay-ToAddModList includes a list of SRAP configuration(s) for each indirectly connected child UE in multi-hop U2N Relay.
17 . The U2N Relay UE of claim 11 , wherein the sl-SRAP-ConfigRelay is included in a RRCReconfiguration message received from the network node.
18 . The U2N Relay UE of claim 11 , wherein the U2N Relay UE is a Last U2N Relay UE.
19 . The U2N Relay UE of claim 11 , wherein the data field includes a RRCSetup message.
20 . The U2N Relay UE of claim 11 , further comprising:
the U2N Relay UE submits the SRAP data PDU to a determined egress RLC channel of a determined egress link.