Uplink in-order delivery for QOS flow offloaded in 5GC multi-RAT dual connectivity

1 . A method, comprising:

establishing, at a first Next Generation (NG) radio access network (RAN) node, an uplink forwarding tunnel with a target node using transport network layer (TNL) information exchanged via an Xn application protocol (XnAP) procedure after a determination is made to offload a quality of service (QoS) flow of a user equipment (UE) to the target node, including encoding, for transmission to the target node, an XnAP message that includes a data forwarding information element proposing uplink forwarding for the QoS flow and receiving, from the target node and in response to the XnAP message, PDU-session-level uplink data-forwarding user-plane TNL information including a tunnel endpoint identifier (TEID) of the target node;

forwarding uplink packets received from the UE of the QoS flow to the target node via the uplink forwarding tunnel;

decoding an end marker Service Data Adaptation Protocol (SDAP) packet data unit (PDU) from the UE; and

in response to reception of the end marker SDAP PDU from the UE, generating a General Packet Radio Service Tunneling Protocol-User Plane (GTP-U) end marker packet that indicates completion of uplink packet forwarding for the QoS flow from the first NG-RAN node to the target node for transmission to the target node via the uplink forwarding tunnel.

2 . The method of claim 1 , further comprising:

determining to offload the QoS flow of the UE to the target node, wherein the target node is a secondary node (SN); and

indicating offloading of the QoS flow to the target node.

3 . The method of claim 2 , further comprising:

comprises a Data Forwarding and Offloading Info from source node information element (IE) that contains an uplink (UL) forwarding IE; and

in response to transmission of the SN addition request or SN modification request, decoding from the SN a Data Forwarding Info from target node IE that comprises a PDU Session level UL data forwarding user plane (UP) tunnel TNL information element that contains a tunnel endpoint identifier (TEID) address of the target node.

4 . The method of claim 1 , further comprising:

determining to offload the QoS flow of the UE to the target node based on an indication from the target node.

5 . The method of claim 4 , further comprising:

from the target node, a secondary node (SN) modification request to offload the QoS flow to the target node, in response to reception of the SN modification request;

encoding for transmission to the target node, an SN modification request acknowledge message that comprises a Data Forwarding and Offloading Info from source node information element (IE) that contains an uplink (UL) forwarding IE; and

in response to transmission of the SN modification request acknowledge message, decoding, from the target node, a Data Forwarding Info from target node IE that comprises a PDU Session level UL data forwarding user plane (UP) tunnel (TNL) information element that contains a tunnel endpoint identifier (TEID) address of the target node.

6 . The method of claim 1 , encoding for transmission to the target node, a secondary node (SN) modification required message that comprises a Data Forwarding and Offloading Info from source node information element (IE) that contains an uplink (UL) forwarding IE; and

in response to transmission of the SN modification required message, decoding from the target node a Data Forwarding Info from target node IE that comprises a PDU Session level UL data forwarding user plane (UP) tunnel TNL information element that contains a tunnel endpoint identifier (TEID) address of the target node.

7 . The method of claim 1 ,

wherein forwarding uplink packets of the QoS flow to the target node comprises forwarding uplink packets received at the first NG-RAN node prior to reception of the end marker SDAP PDU, and wherein uplink packets of the QoS flow received after the end marker SDAP PDU are not forwarded via the uplink forwarding tunnel.

8 . The method of claim 1 ,

wherein the uplink forwarding tunnel is established on a per-QoS-flow basis within a PDU session, and wherein uplink packets associated with different QoS flows of the PDU session are forwarded via different uplink forwarding tunnels or are not forwarded.

9 . An apparatus, comprising:

a memory; and

processing circuitry in communication with the memory, wherein the processing circuitry is configured to:

establish, at a first Next Generation (NG) radio access network (RAN) node, an uplink forwarding tunnel with a target node using transport network layer (TNL) information exchanged via an Xn application protocol (XnAP) procedure after a determination is made to offload a quality of service (QoS) flow of a user equipment (UE) to the target node, including encoding, for transmission to the target node, an XnAP message that includes a data forwarding information element proposing uplink forwarding for the QoS flow and receiving, from the target node and in response to the XnAP message, PDU-session-level uplink data-forwarding user-plane TNL information including a tunnel endpoint identifier (TEID) of the target node;

buffer packets associated with the QoS flow received from the UE after establishment of the uplink forwarding tunnel;

decode a General Packet Radio Service Tunneling Protocol-User Plane (GTP-U) end marker packet received from the source node via the uplink forwarding tunnel; and

in response to reception of the GTP-U end marker packet from the source node via the uplink forwarding tunnel, encode the buffered packets for transmission to a 5th Generation (5G) core network.

10 . The apparatus of claim 9 ,

wherein the processing circuitry is further configured to decode an indication from the source node to offload the QoS flow of the UE to the target node, wherein the target node is a secondary node (SN).

11 . The apparatus of claim 10 ,

wherein the processing circuitry is further configured to:

decode, from the source node, an SN addition request or an SN modification request that comprises a Data Forwarding and Offloading Info from source node information element (IE) that contains an uplink (UL) forwarding IE; and

in response to reception of the SN addition request or SN modification request, encode, for transmission to the source node, a Data Forwarding Info from target node IE that comprises a PDU Session level UL data forwarding user plane (UP) tunnel (TNL) information element that contains a tunnel endpoint identifier (TEID) address of the target node.

12 . The apparatus of claim 9 ,

wherein the source node is a secondary node (SN).

13 . The apparatus of claim 12 ,

wherein the processing circuitry is further configured to determine to offload the QoS flow of the UE to the target node.

14 . The apparatus of claim 13 ,

wherein the processing circuitry is further configured to:

encode, for transmission to the SN, an SN modification request to offload the QoS flow of the UE to the target node;

in response to transmission of the SN modification request, decode from the SN, an SN modification request acknowledge message that comprises a Data Forwarding and Offloading Info from source node information element (IE) that contains an uplink (UL) forwarding IE; and

in response to reception of the SN modification request acknowledge message, encode for transmission to the SN a Data Forwarding Info from target node IE that comprises a PDU Session level UL data forwarding user plane (UP) tunnel TNL information element that contains a tunnel endpoint identifier (TEID) address of the target node.

15 . The apparatus of claim 12 ,

wherein the processing circuitry is further configured to decode an indication from the SN to offload the QoS flow of the UE to the SN.

16 . The apparatus of claim 15 ,

wherein the processing circuitry is further configured to:

decode, from the SN, a SN modification required message that comprises a Data Forwarding and Offloading Info from source node information element (IE) that contains an uplink (UL) forwarding IE; and

in response to reception of the SN modification required message, encode for transmission to the SN a Data Forwarding Info from target node IE that comprises a PDU Session level UL data forwarding user plane (UP) tunnel TNL information element that contains a tunnel endpoint identifier (TEID) address of the target node.

17 . A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors to:

establish, at a first Next Generation (NG) radio access network (RAN) node, an uplink forwarding tunnel with a target node using transport network layer (TNL) information exchanged via an Xn application protocol (XnAP) procedure after a determination is made to offload a quality of service (QoS) flow of a user equipment (UE) to the target node, including encoding, for transmission to the target node, an XnAP message that includes a data forwarding information element proposing uplink forwarding for the QoS flow and receiving, from the target node and in response to the XnAP message, PDU-session-level uplink data-forwarding user-plane TNL information including a tunnel endpoint identifier (TEID) of the target node;

forward uplink packets received from the UE of the QoS flow to the target node via the uplink forwarding tunnel;

decode an end marker Service Data Adaptation Protocol (SDAP) packet data unit (PDU) from the UE; and

in response to reception of the end marker SDAP PDU from the UE, generate a General Packet Radio Service Tunneling Protocol-User Plane (GTP-U) end marker packet for that indicates completion of uplink packet forwarding for the QoS flow from the first NG-RAN node to the target node transmission to the target node via the uplink forwarding tunnel.

18 . The non-transitory computer-readable storage medium of claim 17 ,

wherein the instructions are further executable by the one or more processors to:

determine to offload the QoS flow of the UE to the target node, wherein the target node is a secondary node (SN); and

indicate offloading of the QoS flow to the target node.

19 . The non-transitory computer-readable storage medium of claim 17 ,

wherein the instructions are further executable by the one or more processors to:

determine to offload the QoS flow of the UE to the target node based on an indication from the target node;

decode, from the target node, a secondary node (SN) modification request to offload the QoS flow to the target node, in response to reception of the SN modification request;

encode for transmission to the target node, an SN modification request acknowledge message that comprises a Data Forwarding and Offloading Info from source node information element (IE) that contains an uplink (UL) forwarding IE; and

in response to transmission of the SN modification request acknowledge message, decode from the target node a Data Forwarding Info from target node IE that comprises a PDU Session level UL data forwarding user plane (UP) tunnel (TNL) information element that contains a tunnel endpoint identifier (TEID) address of the target node.

20 . The non-transitory computer readable storage medium of claim 17 , wherein the instructions are further executable by one or more processors to cause the target node to:

buffer uplink packets received via the uplink forwarding tunnel until the GTP-U end marker packet is received; and

forward the buffered uplink packets toward the 5G core network only after reception of the GTP-U end marker packet.