WO2025171589A1

WO2025171589A1 - User plane traffic mapping

Info

Publication number: WO2025171589A1
Application number: PCT/CN2024/077278
Authority: WO
Inventors: Xiang Xu; Ugur Baran ELMALI; Ilkka Antero Keskitalo; Salman Nadaf; Alessio Casati
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Priority date: 2024-02-16
Filing date: 2024-02-16
Publication date: 2025-08-21
Anticipated expiration: 2026-08-16

Abstract

Example embodiments of the present disclosure relate to user plane traffic mapping. In an aspect, a first network device establishes a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device. The first network device determines a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information. In this way, the user plane traffic mapping, especially traffic mapping between a QoS flow of a terminal device and a QoS flow of mobile termination of a relay node can be improved.

Description

USER PLANE TRAFFIC MAPPING

FIELD

Example embodiments of the present disclosure generally relate to the field of communication, and in particular, to a terminal device, a network device, methods and apparatuses for user plane traffic mapping, for example for improving traffic detection and mapping between a quality of service (QoS) flow of a terminal device and a QoS flow of a mobile termination (MT) of a relay node.

BACKGROUND

A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server.

Such communication networks operate in according with standards such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute) . Examples of standards are the so-called 5G (5th Generation) standards provided by 3GPP.

SUMMARY

In general, example embodiments of the present disclosure provide a solution for user plane traffic mapping, for example for improving traffic detection and mapping between a QoS flow of a terminal device and a QoS flow of MT of a relay node.

In a first aspect, there is provided a first network device. The first network device may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the first network device at least to: establish a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and determine a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information.

In a second aspect, there is provided a third network device. The third network device may comprise at least one processor and at least one memory storing instructions of a session management function (SMF) that, when executed by the at least one processor, cause the third network device at least to: receive, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and transmit the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.

In a third aspect, there is provided a fourth network device. The fourth network device may comprise at least one processor and at least one memory storing instructions of a first user plane function (UPF) that, when executed by the at least one processor, cause the fourth network device at least to: receive, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) ; determine, based on the indication, transport network layer, (TNL) information related to a downlink user plane traffic of the terminal device; and transmit the TNL information to the SMF.

In a fourth aspect, there is provided a method implemented at a first network device. The method may comprise: establishing a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and determining a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information.

In a fifth aspect, there is provided a method implemented at a third network device. The method may comprise: receiving, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and transmitting the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.

In a sixth aspect, there is provided a method implemented at a fourth network device. The method may comprise: receiving, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) ; determining, based on the indication, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and transmitting the TNL information to the SMF.

In a seventh aspect, there is provided an apparatus. The apparatus may comprise: means for establishing a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and means for determining a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information.

In an eighth aspect, there is provided an apparatus. The apparatus may comprise: means for receiving, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and means for transmitting the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.

In a ninth aspect, there is provided an apparatus. The apparatus may comprise: means for receiving, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) ; means for determining, based on the indication, transport network layer, (TNL) information related to a downlink user plane traffic of the terminal device; and means for transmitting the TNL information to the SMF.

In a tenth aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus at least to perform at least the method according to any of the fourth aspect to the sixth aspect of the present application.

In an eleventh aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus at least to perform at least the method according to any of the fourth aspect to the sixth aspect of the present application.

In a twelfth aspect, there is provided a first network device. The first network device may comprise: establishing circuitry for establishing a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and determining circuitry for determining a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information.

In a thirteenth aspect, there is provided a third network device. The third network device may comprise: receiving circuitry for receiving, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and transmitting circuitry for transmitting the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.

In a fourteenth aspect, there is provided a fourth network device. The fourth network device may comprise: receiving circuitry for receiving, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) ; determining circuitry for determining, based on the indication, transport network layer, (TNL) information related to a downlink user plane traffic of the terminal device; and transmitting circuitry for transmitting the TNL information to the SMF.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, in which:

Fig. 1 illustrates an example of a network environment in which some embodiments of the present disclosure may be implemented;

Fig. 2A illustrates an example of a network architecture in which some embodiments of the present disclosure may be implemented;

Fig. 2B illustrates a user plane protocol stack for a wireless access backhaul architecture in which some embodiments of the present disclosure may be implemented;

Fig. 3 illustrates an example signaling process for improving traffic mapping in accordance with some embodiments of the present disclosure;

Fig. 4 illustrates an example call flow for improving traffic detection and mapping in accordance with some embodiments of the present disclosure;

Fig. 5 illustrates a flowchart of an example method implemented at a first network device in accordance with some embodiments of the present disclosure;

Fig. 6 illustrates a flowchart of an example method implemented at a third network device in accordance with some embodiments of the present disclosure;

Fig. 7 illustrates a flowchart of an example method implemented at a fourth network device in accordance with some embodiments of the present disclosure;

Fig. 8 illustrates a simplified block diagram of a device that is suitable for implementing some embodiments of the present disclosure; and

Fig. 9 illustrates a block diagram of an example of a computer-readable medium in accordance with some embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION

Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein may be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes” , “including” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or” , mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the future fifth generation (5G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (e.g., remote surgery) , an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

As agreed, there are other architecture options that can achieve the functionality of vehicle-mounted relays (VMR) as defined in TS 22.261. One such option is the so-called “Velcro” solution. In this solution, the Wireless Access Backhaul, WAB, -node as a relay node typically consists of a gNB (5G Node B) and a WAB-MT (WAB Mobile Termination) , which provides the radio connection for the new radio (NR) backhaul. The gNB in the relay node establishes N2 interface to an access and mobility management function (AMF) residing and N3 interface to a user plane function (UPF) in the 5G Core Network (5GC) over a protocol data unit (PDU) session. That is to say, the WAB-node utilizes next generation interfaces (for example, N2 interface and N3 interface) , both for control and user planes, to transparently forward data through the serving network. The WAB-node is responsible for transporting data between the base stations and the core network, ensuring efficient and reliable communication. This allows for efficient data transmission between the WAB-node and the core network (for example, the AMF and user plane functions (UPF) for the WAB or the UE in 5GC) , while providing seamless connectivity to UEs (User Equipment) connected to the WAB-node.

The main principle is that the backhaul BH connection for the WAB-gNB is provided by a PDU session established for the WAB-MT to the serving network. That is to say, the PDU session established for the WAB-MT to the serving network provides the New Radio (NR) BH connection for the WAB-gNB. WAB-gNB NG interfaces (for both control and user plane) are transparently forwarded through the serving network. When a UE is connected to the WAB-node, it sees the WAB cell as a normal cell (for example, a 5G cell) , and the UE can establish a PDU session to the UE next generation core network (NGCN, also known as 5GC as specified in TS 23.501) (for example, the UPF of the UE) using signaling procedures. That is to say, the UE connected to the WAB-node sees the WAB cell like a normal cell and the UE can establish PDU session to the UE NGCN through signaling procedures. The WAB deployment is therefore transparent to UEs and no enhancements are needed for normal UEs.

For a UE connected with WAB, a PDU session is established for the UE. The PDU session can be used to transfer one or more QoS flows. Each QoS flow is identified by a QoS flow IF (QFI) . The PDU session uses one general packet radio service tunneling protocol user plane (GTP-U) tunnel to transfer the uplink (UL) next generation user plane (UL NG-U) packet from the gNB to the UPF, and to transfer the downlink (DL) NG-U packet from the UPF to the gNB. In the DL direction, the (UPF) of the UE sends a down link next generation user plane (DL NG-U) packet with the destination IP address, which is set to the IP address of the WAB-gNB (i.e. the IP address of the co-located WAB-MT) . This IP address is known to the WAB’s UPF (i.e. a UPF serving a WAB or a part of UPF serving a WAB, for example, the WAB -MT’s UPF) , and accordingly, this IP packet (including the DL NG-U packet) is routed to the WAB’s UPF. The WAB’s UPF performs traffic detection and mapping of a quality of service (QoS) flow of the UE in the DL NG-U packet to an appropriate QoS flow of WAB-MT. The traffic mapping in the UPF is based on a rule provided by the SMF. The traffic detection and mapping can be based on at least one of the TNL information, for example, the information of the IP header. For example, the traffic detection and mapping may be based on the IP address, or DSCP, or SPI, or the combination of one or more TNL information.

However, the above mapping may not be performed by UPF of the WAB. Since UPF of the WAB cannot decode the NG-U packet of the UE which is ciphered, it neither knows the destination UE, nor the QoS flow of the NG-U packet of the UE (since the QFI is inside the NG-U packet of the UE which is ciphered) . The UPF of the WAB also does not know which UE’s UPF has sent the DL NG-U packet. Therefore, the WAB’s UPF may not be able to perform correct traffic detection and mapping. Without the correct traffic mapping in the WAB’s UPF, a donor may not be able to map a DL NG-U packet of the UE to a correct data radio bearer (DRB) . DRB is a radio bearer used to transmit user plane information. In the 5G network, user data is carried in QoS flows which are mapped to the DRB(s) by the service data adaptation protocol (SDAP) layer. Without the correcting mapping of the DL NG-U packet of the UE to the DRB, the QoS of the UE cannot be guaranteed.

According to some embodiments of the present disclosure, there is provided a solution for user plane traffic detection and mapping, especially for improving traffic detection and mapping between a QoS flow of a terminal device and a QoS flow of MT of a relay node. In this solution, a first network device (for example, a relay node) establishes a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and also determines a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information. The TNL information includes at the least the information of the transmitter of the DL NG-U packet, for example, the IP address, port number, and other TNL parameter/information used by the UE’s UPF to send a further DL IP packet including the UE’s DL NG-U packet. The determined rule informs the second UPF (for example, the UPF serving the first network device) regarding how to map an IP packet carrying the UE’s DL NG-U packet to a specific QoS flow of the WAB-MT’s PDU session. The rule may be used by the second UPF serving the first network device to perform traffic detection and mapping for wireless access backhauling, and the QoS for terminal device can be guaranteed.

Fig. 1 illustrates an example of a network environment 100 in which some embodiments of the present disclosure may be implemented. In the descriptions of the example embodiments of the present disclosure, the network environment 100 may also be referred to as a communication system 100 (for example, a portion of a communication network) . For illustrative purposes only, various aspects of example embodiments will be described in the context of one or more terminal devices and network devices that communicate with one another. It should be appreciated, however, that the description herein may be applicable to other types of apparatus or other similar apparatuses that are referenced using other terminology.

The communication system 100 comprises a network device 101 (for example, functioned as a relay network device) and several terminal devices 102, and the network device 101 may provide services to the terminal device 102, and the network device 101 and the terminal device 102 may communicate data and control information with each other. In some embodiments, the network device 101 and the terminal device 102 may communicate with direct links/channels. The communication system 100 may further comprise a network device 103 for communicating with the network device 101 functioned as a relay node. In some embodiments, the network device may be a core network device and comprises a plurality of network functions, for example, a first network function NF1, a second network function NF2, a third network function NF3, a fourth network function NF4, and a fifth network function NF5.

Fig. 2A illustrates an example of a network architecture in which some embodiments of the present disclosure may be implemented. It is understood that a UE 120 may be example of the terminal device 102, the WAB node 110 may be an example of the network device 101. Further, the UE’s UPF 130, the donor 140, and the WAB’s UPF 150 may be examples of network functions.

As shown in Fig. 2A, a WAB-node 110 functioned as a relay node may be an example of the network device 101. The WAB node 110, which is a relay node, consists of a gNB (5G Node B) 111 and a mobile termination part (WAB-MT) 112, and the WAB-MT 112 provides the radio connection for the new radio (NR) backhaul (BH) . The gNB 111 in the relay node establishes N2 and N3 interfaces to an AMF and UPF residing in the 5GC over a PDU session. The PDU session, which is established for the WAB-MT 112 to the serving network (for example, the UPF) , provides the BH connection for the WAB-gNB 111. That is to say, WAB-gNB BH (i.e. the NG interfaces to the NGCN) goes through the PDU session established for the WAB-MT. When a UE 120 is connected to the WAB-node 110, the UE 120 sees the WAB cell as a normal cell (for example, a 5G cell) , and the UE 120 can establish a PDU session to the UE’s UPF 130 (for example, a UPF 130 for serving the UE 120) using signaling procedures.

In the communication system, between the WAB node 110 and the UE’s UPF 130, there are two network devices, for example, a donor device 140 (for example, a gNB) and a UPF 150 of the WAB 110 (for example, a UPF 150 for serving the WAB-MT 112, or WAB’s UPF) . In the uplink direction, the data from the UE 120 transmits to the WAB node 110, the donor device 140, the WAB’s UPF 150, and then to the UE’s UPF 130 sequentially. In the downlink direction, the data from the UE’s UPF 130 is transmitted to the WAB’s UPF 150, the donor device 140, the WAB node 110, and then to the UE 120 sequentially.

Communications in the network environment 100 may be implemented according to any proper communication protocol (s) , including, but not limited to, cellular communication protocols of the fourth generation (4G) and the fifth generation (5G) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, including but not limited to: Code Division Multiple Access (CDMA) , Frequency Division Multiple Access (FDMA) , Time Division Multiple Access (TDMA) , Frequency Division Duplex (FDD) , Time Division Duplex (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiple (OFDM) , Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and/or any other technologies currently known or to be developed in the future.

It is to be understood that the number of devices and their connection relationships and types shown in Fig. 1 are for illustrative purposes only without suggesting any limitation. The communication system 100 may include any suitable number of devices adapted for implementing embodiments of the present disclosure.

Fig. 2B illustrates a user plane protocol stack for a WAB architecture in accordance with some embodiments of the present disclosure. As shown in Fig. 2B, in downlink direction, the UE’s UPF 130 uses the packet filter provided by the UE 120 for packet detection, e.g. identify the related QoS flow and add the QoS flow identity (QFI) in the NG-U general packet radio service tunneling protocol user plane (GTP-U) header. If the WAB node 110 (for example, gNB) receives the QFI, the WAB 110 serving the UE 120 performs further mapping from QoS flow of the DL NG-U to the DRB of the UE.

During the PDU Session Establishment procedure for WAB-MT, the WAB-MT 112 is assigned with an IP address. This IP address is used by the co-located WAB-gNB 111 for NG-control plane/user plane (NG-C/NG-U) . For a UE 120 connected with WAB 110, the UE’s UPF 130 sends a DL NG-U packet with destination IP address, which is set to the IP address of WAB-gNB 111 (i.e. the IP address of the co-located WAB-MT 112) . This IP address is known by the WAB’s UPF 150 (for example, the WAB-MT’s UPF 150, a UPF 150 for serving the WAB-MT 112) , and accordingly, this IP packet (including the DL NG- U packet) is routed to the WAB’s UPF 150. The WAB’s UPF 150 performs traffic mapping of a QoS flow of the UE in the DL NG-U packet to an appropriate QoS flow of WAB-MT 112.

A plurality of terminal devices 120 may communicate with a same WAB node 110, and the plurality of UEs 120 connected with the WAB node 110 may use different UPFs 130, and thus an NG-U tunnel of the UE 120 may multiplex up to 64 QoS flows. Each QoS Flow has its own QoS. The NG-U tunnels of the UEs 120 from different UPFs 130 may use same IP address of the WAB-MT 112. Multiple NG-U tunnels (between the WAB 110 and the UE’s UPF 130) of the UE 120 can be multiplexed into one NG-U tunnel (between donor 140 and the WAB’s UPF 150) of the WAB. The NG-U tunnel of the UE 120 is ciphered, such that only the source (the UE’s UPF 130) and destination nodes (the WAB 110) can decode the GTP-U header. The GTP-U packets of the UE 120 are encapsulated in GTP-U packet of the WAB-MT 112 to be sent to the donor 140. Thus, the donor 140 can only see the GTP-U header of GTP-U packet of the WAB-MT 112, but cannot see the inner GTP-U header of GTP-U packet of the UE 120 which is ciphered and encapsulated in the s GTP-U packet of the WAB-MT 112.

As mentioned above, for the UE 120 connected with WAB 110, the UE’s UPF 130 sends a DL NG-U packet with the destination IP address set to IP address of the WAB-gNB 111 (i.e. the IP address of the co-located WAB-MT 112) . This IP packet is routed to the WAB’s UPF 150. The WAB’s UPF 150 performs traffic mapping of the IP packet to an appropriate QoS flow of WAB-MT 112. For example, it is assumed that the WAB-MT 112 has 2 QoS flows:

- QoS flow #1 with 5QI=2; and

- QoS flow #2 with 5QI=3.

For example, it is assumed that a specific PDU session of the UE 120 has 2 QoS flows:

- QoS flow #10 with 5QI=3; and

- QoS flow #11 with 5QI=2.

Ideally, the WAB’s UPF 150 may perform the following mapping

- for packet associated with UE’s QoS flow #10 (with 5QI=3) , map it to WAB’s QoS flow #2 (with 5QI=3)

- for packet associated with UE’s QoS flow #11 (with 5QI=2) , map it to WAB’s QoS flow #1 (with 5QI=2) .

In 5G, a “PDU Session” can be used to provide end-to-end user plane connectivity between the UE and a specific Data Network (DN) through the UPF. A PDU Session supports one or more QoS Flows. There is a one-to-one mapping between QoS Flow and QoS profile, i.e. all packets belonging to a specific QoS Flow have the same “5G Quality of Service Identifier” (5QI) .

However, the above ideal mapping may not be performed by the WAB’s UPF 150. Since the WAB’s UPF 150 cannot decode the UE’s NG-U packet which is ciphered, it neither knows the destination UE, nor the QoS flow of the UE’s NG-U packet (since the QFI is inside the UE’s NG-U which is ciphered) . Therefore, the WAB’s UPF may not be able to perform correct traffic detection and mapping. Without the correct traffic detection and mapping in the WAB’s UPF, a donor may not be able to map a DL NG-U packet of the UE to a correct data radio bearer (DRB) . DRB is a radio bearer used to transmit user plane information. In the 5G network, the data wireless bearer transmits user data by mapping to QoS flow, and the QoS Flow is then mapped to the DRB by the service data adaptation protocol (SDAP) layer. Without the correcting mapping of the DL NG-U packet of the UE to the DRB, the QoS of the UE cannot be guaranteed.

Hereinafter, an example signaling process 300 for improving traffic detection and mapping in accordance with some embodiments of the present disclosure will be described with reference to Fig. 3.

In the process 300, the first network device 301 transmits (310) to a second network device 302, an indication 201 that a terminal device 102 or the UE 120 is communicating with the first network device 301 which functions as a relay including a base station function. In some embodiments, the first network device 301 may be a WAB node 110 functioned as a relay node as shown in Fig. 2A and 2B, and the second network device 302 may be a mobility management function (AMF) associated with or serving the UE 120, i.e. a UE’s AMF. The transmission of the indication 201 to the second network device may be performed through several network entities, for example, a donor gNB 140 and a WAB’s UPF 150, between the first network device 301 (for example, the WAB node 110) and second network device 302 (for example, the UE’s AMF) .

In some embodiments, the indication 201 that a terminal device 102 or the UE 120 is communicating with the first network device 301is transmitted from the first network device 301 to the second network device 302 by sending a next generation application protocol (NGAP) message comprising the indication 201 to the second network device 302, or by transmitting, to the second network device 302, the indication 201 during a next generation (NG) setup procedure. In some embodiments, the indication 201 is transmitted by a gNB (for example, gNB 111 of the WAB node 110) to the second network device 302.

Then, the second network device 302 receives (315) the indication 201, and transmits (320) the indication 201 to a third network device 303. Then, the third network device 303 receives (325) the indication 201. In some embodiments, the third network device 303 may be a session management function (SMF) serving the terminal device 100, for example, the UE’s SMF. In some embodiments, the indication 201 is transmitted by the second network device 302 to the third network device 303 by initiating a protocol data unit (PDU) session service operation to the third network device 303 to create or modify context of the terminal device in the third network device 303.

Then, the third network device 303 transmits (330) the indication 201 to the fourth network device 304, and the fourth network device 304 receives (335) the indication 201. In some embodiments, the fourth network device 304 may be a user plane function, UPF, serving the UE 120, for example, UE’s UPF 130. For example, the fourth network device 304 comprises a UPF serving the terminal device connected with the first network device. In some embodiments, the indication 201 is transmitted from the third network device 303 to the fourth network device 304 by transmitting the indication 201 via a N4 session establishment or modification request to the fourth network device 304.

Upon receiving the indication 201 that a UE 120 is communicating with a first network device 301 which functions as a relay including a base station function, the fourth network device 304 determines (336) the transport network layer (TNL) information 202 related to a user plane function (UPF) serving the UE 120, for example, related to the UE’s UPF 130. Then, the fourth network device 304 transmits (340) the TNL information 202 to the third network device 303, and the third network device 303 receives (345) the TNL information 202. For example, by knowing the terminal device is accessing via a first network device functioning as a relay node, the fourth network device 304 (for example, UE’s UPF) includes the additional TNL information in the response to the third network device 303 (for example, UE’s SMF) . In some embodiments, the TNL information 202 is transmitted to the third network device 303 by transmitting, to the third network device 303, a N4 session establishment response or N4 session modification response that includes the TNL information 202.

In some embodiments, the TNL information comprises information for transmitting downlink (DL) next generation user plane (NG-U) packet. In some embodiments, the TNL information comprises: an internet protocol (IP) address of the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; a port number of the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; an outer IP address of a downlink user plane traffic related to the terminal device; a security parameters index (SPI) related to a downlink user plane traffic; a differentiated services code point (DSCP) value to be used by the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; an internet protocol version 6 (IPv6) flow label to be used by the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or any combination thereof. In some embodiments, the DSCP value and the IPv6 flow label are assigned per QoS flow of the terminal device.

Then, the third network device 303 transmits (350) the TNL information to the second network device 302, and the second network device 302 receives (355) the TNL information 202. In some embodiments, the TNL information is transmitted by transmitting a transfer message that includes the TNL information to the second network device 302. In some embodiments, the TNL information is transmitted by transmitting an information element (IE) that includes the TNL information, to the second network device 302. For example, the IE is related to the third network device 303 and transparent to the second network device 302. In some embodiments, the TNL information is included in: a next generation application protocol (NGAP) protocol data unit (PDU) session resource setup request transfer IE; a PDU session resource modify request transfer IE; or any combination thereof.

Then, the second network device 302 transmits (360) the TNL information 202 to the first network device 301, and the first network device 301 receives (365) the TNL information 202. In some embodiments, the TNL information 202 is transmitted by transmitting, to the first network device 301, a message comprising the TNL information in information element (IE) related to the third network device. For instance, the message comprises a next generation application protocol (NGAP) protocol data unit (PDU) session resource setup request message or PDU session resource modify request message. It should be noted that the TNL transmission from the second network device 302 to the first network device 301 may involve several entities there between.

Upon reception of the TNL information, the first network device 301 determines (370) a rule 203 to be used for traffic detection and mapping, based on the TNL information 202. In some embodiments, the rule to be used for traffic detection and mapping is determined by the gNB (for example, WAB’s gNB 111) included in the first network device 301, and then the determined rule 203 is transmitted from the gNB to the MT (for example, WAB’s MT 112) , and then the MT 112 transmits (375) the rule 203 to a AMF 306 associated with or serving the first network device 301, for example a AMF (i.e. WAB-MT’s AMF) serving a mobile termination of the first network device 201. In some embodiments, the TNL information is transmitted by the gNB to the MT, and the rule 203 is determined at the MT 112, and then the MT 112 transmits (375) the rule 203 to the AMF 306 associated with or serving the first network device.

In some embodiments, the rule may comprise a protocol data unit (PDU) session identity (ID) ; a quality of service (QoS) flow ID; a source IP address of a downlink user plane traffic related to the terminal device; a source port number of a downlink user plane traffic related to the terminal device; an outer IP address of a downlink user plane traffic related to the terminal device; a SPI related to a downlink user plane traffic; a DSCP value of a downlink user plane traffic related to the terminal device; an IPv6 flow label of a downlink user plane traffic related to the terminal device; or any combination thereof.

The AMF 306 transmits (382) the rule 203 to a SMF 307 (for example, WAB-MT’s SMF) serving the first network device. Then the SMF 307 receives (384) and transmit (386) the rue 203 to a fifth network device 305. Then, the fifth network device 305 receives (388) the rule 203. In some embodiments, the fifth network device 305 comprises a UPF serving the MT of the first network device 301. For example, the WAB-MT sends the rule (e.g. a QoS rule) to WAB-MT's AMF 306, and WAB-MT's AMF 306 sends the rue to WAB-MT's SMF 307, then SMF 307 may construct a Packet Detection rule (PDR) . Then, the WAB-MT's SMF 307 send the rule to the fifth network device 305 (for example, the WAB’s UPF) .

The fourth network device 304 transmits (390) downlink data 204 including the TNL information and related to a QoS of the terminal device, to the fifth network device 305. That is to say, the fourth network device 304 transmits the data according to the TNL information to the fifth network device 305 for performing traffic detection and mapping. Upon reception of the rule 203 and the downlink data 204, the fifth network device 305 performs (396) a traffic mapping between a QoS flow of the terminal device (for example, the UE 120) and a QoS flow of the MT of the first network device (for example, WAB’s MT 112) . In some embodiments, the downlink data 204 comprising the TNL information comprises a downlink next generation user plane (DL NG-U) packet including the TNL information. In some embodiments, the traffic mapping comprises: mapping the QoS flow of the terminal device related to the DL NG-U packet to the QoS flow of the MT.

By the process 300, it may enhance the control plane (CP) signaling to provide the additional TNL information of the fourth network device 304 to a gNB of the first network device 301, then the co-located MT in the first network device 301 or the gNB of the first network device 301 may configure, based on the TNL information, the DL packet filter or rule to be used for traffic detection and mapping, such that the fifth network device 305 can treat the NG-U traffic appropriately based on the rule, e.g., map a DL NG-U IP packet of a terminal device to a right QoS flow of MT of the first network device 301. Compared to the current approach which only provides the first network device 301 with the NG-U endpoint used in the fourth network device 304 for receiving UL NG-U packet, i.e. only provides the UL NG-U F-TEID to the gNB of the first network device 301, the additional TNL information according to the present disclosure provided to the first network device 301 at least comprises the NG-U endpoint in the fourth network device 304 for sending DL NG-U packet.

By including the TNL information in the response information from the fourth network device 304, the DL NG-U packet may be transmitted to the gNB of the first network device 301, and based on the TNL information, the gNB or MT of the first network device 301 may configure the DL packet filter or rule for traffic detection and mapping. The TNL information includes at the least the information of the transmitter of the DL NG-U packet, for example, the IP address, port number, and other TNL parameter/information used by the UE’s UPF to send a further DL IP packet including the UE’s DL NG-U packet. The UEs connected with the same WAB may use different UPFs. Each UE’s UPF may be configured with different policy for setting the TNL information of the DL NG-U packet. By knowing the TNL information used by each transmitter (i.e. UE’s UPF) for DL NG-U, the determined rule can identify a specific NG-U packet from a UE’s UPF. The determined rule informs the second UPF (for example, the UPF serving the first network device, i.e. the fifth network device 305) regarding how to map an IP packet carrying the UE’s DL NG-U packet to a specific QoS flow of the WAB-MT’s PDU session. In this way, the fifth network device 305 can decode the UE’s NG-U packet which is ciphered based on the configured DL packet filter or rule, and the fifth network device 305 may know the destination UE and the QoS flow of the UE’s NG-U packet. Therefore, the fifth network device 305 may be able to perform correct traffic detection and mapping between the QoS of terminal device and the QoS of the MT of the first network device, and the QoS for the UE 120 can be guaranteed.

Hereinafter, an example call flow 400 for improving traffic detection and mapping in accordance with some embodiments of the present disclosure will be described with reference to Fig. 4. It may be understood that the WAB 110 (comprising a WAB gNB 111 and a WAB MT 112) may be an example of the first network device 301; the UE 120 may be an example of the terminal device; the UE’s AMF 160 may be an example of the second network device 302; the UE’s SMF 170 may be an example of the third network device 303; the UE’s UPF 130 may be an example of the fourth network device 304; and the WAB’s UPF 150 may be an example of the fifth network device 305.

As illustrated in Fig. 4, at 410, the WAB-MT 112 connects with the donor 140. The WAB-MT 112 setup a PDU session resource via a PDU session establishment procedure defined in specification, such as, TS 23.502. Therefore, the DL packet filter provided from the UE 120 is provided to the WAB’s UPF 150. The WAB-MT 112 is assigned with an IP address anchored in the WAB’s UPF 150, and the IP address is also the address of the WAB-gNB for NG-control plane/user plane (NG-C/NG-U) , and thus the IP address is known by the WAB’s UPF 150.

For example, the WAB-MT’s PDU session may include:

- QoS Flow #1 with 5QI=2 (priority level = 40, packet delay budget (PDB) =150ms) ; and

- QoS Flow #2 with 5QI=3 (priority level = 10, PDB=50ms) .

At 420, the UE 120 connected with the WAB 110 (for example, the WAB gNB 111) . The UE 120 initiated a PDU Session Establishment procedure. When the WAB 110 sends the next generation application protocol (NGAP) message (including the encapsulated non-access stratum (NAS) PDU session establishment/modification request) , the NGAP message includes a flag indicating the UE is accessing via a WAB. Alternatively, this indication may be provided by WAB 110 to the UE’s AMF 160 during the NG Setup procedure.

At 430, the UE’s AMF 160 initiates a network-selected mobile multimedia broadcast service (Nsmf) operation to create UE context in UE’s SMF 170. The UE’s AMF 160 may indicate to the UE’s SMF 170 that the UE 110 is accessing via a WAB 110 or is communicating with the WAB 110. That is to say, the WAB node 110 indicates to the UE’s SMF 170 via the UE’s AMF 160 that the UE 120 is accessing via the WAB 110.

At 440, the UE’s SMF 170 initiates an N4 Session Establishment/Modification Request to the UE’s UPF 130. In this way, the UE’s SMF 170 informs the UE’s UPF 130 that UE is accessing via a WAB 110. Then, at 450, the UE’s UPF 130 acknowledges the indication by sending an N4 session establishment/modification Response to the UE’s SMF 170. By knowing the UE 120 is accessing via a WAB 110, the UE’s UPF 130 may include the additional transport network layer (TNL) information in the N4 Session Establishment/Modification Response. That is to say, the TNL information is included in the N4 Session Establishment/Modification Response transmitted at 450. As for TNL information, it may refer to the information in the network transport layer, which provides end-to-end data transmission services. The TNL information usually includes source and destination addresses, port numbers, data transmission sequence and flow control, etc. During network transmission, TNL information is used to identify and route data packets to ensure that the data reaches the destination correctly.

In some embodiments, the additional TNL information includes user plane endpoint information used in the UPF of the terminal device for transmitting DL NG-U packet, for example, the GTP-U endpoint information (IP address, port number) used in UE’s UPF 130 for sending DL NG-U. The GTP-U endpoint information refers to information related to the GTP-U protocol endpoint, including node identification, IP address, port number, etc. Each GTP-U endpoint is identified by a TEID (Tunnel Endpoint Identifier) , which is used to uniquely identify a GTP-U tunnel. In addition, the GTP-U endpoint also needs to know the IP address and port number of the peer node (Peer) in order to establish and maintain the GTP-U tunnel.

It should be understood that the current UPF only provide UL GTP-U endpoint in UE’s UPF 130 for receiving UL NG-U, but not for transmitting DL NG-U, to the gNB 111 via SMF 170 and AMF 160. That is to say, the additional TNL information according to the present disclosure provided to WAB 110 at least includes the NG-U endpoint in the UPF 130 for sending DL NG-U packet. Current standard only provides WAB 110 with the NG- U endpoint in the UPF 130 for receiving UL NG-U packet, i.e. the UE’s SMF 170 provide the UL NG-U F-TEID to the gNB 111.

In some embodiments, the additional TNL information includes an outer internet protocol (IP) address in the case that internet protocol security (IPSec) tunnel mode is used to protect the NG-U packet of the terminal device. In case that IPSec tunnel is used to protect the NG-U, the IP address is the outer IP address. In some embodiments, the additional TNL information includes a differentiated services code point (DSCP) information that the UPF of the terminal device plans to use for the DL NG-U packet, optionally, this information may be per UE’s QoS flow. In some embodiments, the additional TNL information includes an internet protocol version 6 (IPv6) flow label that the UPF of the terminal device plans to use for the DL NG-U packet, and optionally, this information may be per UE’s QoS flow.

At 460, the UE’s SMF 170 transmits Nsm_Communication_N1N2 Message Transfer including the additional TNL information received from the UE’s UPF 130 to the UE’s AMF 160, to create SMF context. For example, the additional TNL information can be included in a SMF-related IE which is transparent to the AMF 160. For example, the additional TNL information can be in added in the NGAP PDU Session Resource Setup Request Transfer information element (IE) , or PDU Session Resource Modify Request Transfer IE, or other SMF related IEs as defined in the specification, such as TS 38.413.

At 470, the UE’s AMF 160 send an NGAP PDU Session Resource Setup Request message, including the additional TNL information in the SMF related IE, to the WAB-gNB 111. That is to say, the UE’s SMF 170 forwards the additional TNL information received from UE’s UPF 130, to the UE’s gNB 111 (i.e. WAB 110 in this case) via the UE’S AMF 160. The control plane (CP) signaling includes the UPF <-> SMF signaling and SMF -> gNB signaling (i.e., SMF-related IEs defined in specification, such as TS38.413) . The additional TNL information provided to WAB at least comprises the NG-U endpoint in the UPF for sending DL NG-U packet.

By now, the normal PDU session setup procedure is performed. The UE’s PDU session is established. For example, the UE’s PDU session has 2 QoS flows.

- QoS flow #10 with 5QI=3; and

- QoS flow #11 with 5QI=2

The WAB-gNB 111 now has following information for UE’s PDU session, for example:

- QoS flow #10 with 5QI=3, UPF’s IP address is 192.168.0.1 and DSCP=a for applicable DL traffic; and

- QoS flow #11 with 5QI=2, UPF’s IP address is 192.168.0.1, DSCP=b for applicable DL traffic.

It should be understood that the IP address of UPF mentioned above is of UE’s UPF 130. The WAB-gNB 111 may transmit this new TNL information to the WAB-MT 112.

Based on the received TNL information, the WAB-MT 112 or the gNB 111 decides to update the rule (or packet filter) to be used for traffic detection and mapping in the WAB’s UPF 150 for a PDU session. For example, the WAB-gNB 111 informs the co-located WAB-MT 112 for the TNL information received from the UE’s UPF 130. In some embodiments, the WAB-MT 112 initiates PDU Session Modification procedure to update the rule in WAB’s UPF 150. In some embodiments, the WAB-MT 112 may initiate PDU Session Establishment procedure to establish a new PDU Session, and provide the rule (packet filter) to be used by WAB’s UPF 150. In some embodiments, the WAB-gNB 111 determines the rule to be used for traffic detection and mapping based on the TNL information. At 480, the WAB-MT 112 transmits the determined rule to the WAB’s UPF 150, for example, through the donor 140, a WAB’s AMF (not shown in Fig. 4) , and a WAB’s SMF (not shown in Fig. 4) .

For example, the rule (packet filter) may be as below:

- QoS Flow ID #1, remote IP address is 192.168.0.1 and DSCP=b for applicable DL traffic; and

- QoS Flow ID #2, remote IP address is 192.168.0.1 and DSCP=a for applicable DL traffic.

At 490, the WAB’s UPF 150 may update the current rule for traffic detection and mapping to be the rule provided by the WAB-MT 112. At 495, the WAB’s UPF 150 receives a DL NG-U packet from the UE’s UPF 130, and the final destination of the DL NG-U is at UE. The DL NG-U packet is transmitted by the UE’s UPF 130 to the WAB’s UPF 150 by using the TNL information, such as at least one of remote IP address (i.e. IP address of UE’s UPF 130) , port number, DSCP or IPv6 Flow Label.

For example, for the UE 120 connected with the WAB 110, the UE’s UPF 130 sends a DL NG-U packet with the destination IP address, which is set to WAB-gNB 111 (i.e. the IP address of the co-located WAB-MT 112) . This IP packet (comprising the DL NG-U packet) is routed to the WAB’s UPF 150. The WAB’s UPF 150 now has a rule to identify a UE’s specific DL NG-U packet based on at least one of remote IP address (i.e. IP address of UE’s UPF 130) , port number, DSCP or IPv6 Flow Label. Based on the updated rule (packet filter) and the DL NG-U packet received from the UE’s UPF 130 via the TNL information, the WAB’s UPF 150 performs traffic detection and mapping based on the IP header, e.g. source IP address, DSCP, etc. Therefore, the WAB’s UPF 150 may perform traffic mapping of a QoS flow of the UE 120 in the DL NG-U packet to an appropriate QoS flow of WAB-MT 112.

For example, the UE’s NG-U packet will be mapped to following WAB-MT’s QoS flow:

- For UE’s QoS Flow #10 (5QI=3) , WAB’s UPF 150 will map it to WAB’s QoS Flow #2 (5QI=3) ; and

- For UE’s QoS Flow #11 (5QI=2) , WAB’s UPF 150 will map it to WAB’s QoS Flow #1 (5QI=2) .

Then, the WAB’s UPF 150 sends the DL NG-U packet encapsulating the UE’s DL NG-U packet therein to the donor 140. The donor 140 performs traffic mapping by mapping the DL packet related to specific QoS Flow (e.g., QoS Flow#2) to a specific DRB, and sends it to WAB-MT 112. Then, the WAB-MT 112 forwards the UE’s DL NG-U packet to the co-located WAB-gNB 111, and then WAB-gNB 111 further sends the DL NG-U packet to the UE.

By the call flow 400, it may enhance the control plane (CP) signaling to provide the additional TNL information of UE’s UPF 130 to the gNB 111, then the co-located WAB-MT 112 in the WAB node 110 configures the DL packet filter to be used in the WAB’s UPF 150, so the WAB’s UPF 150 can treat the NG-U traffic appropriately, e.g., map a UE’s DL NG-U IP packet to a right QoS flow of WAB-MT 112. Compared to the current approach which only provides the WAB node 110 with the NG-U endpoint used in the UE’s UPF 130 for receiving UL NG-U packet, for example, the UE’s SMF 170 only provide the UL NG-U F-TEID to the gNB 111 via the UE’s AMF 160, the additional TNL information of the present disclosure provided to WAB node 110 of the present disclosure at least comprises the NG-U endpoint in the UPF for sending DL NG-U packet.

By including the TNL information in the response information from the UE’s UPF 130, the DL NG-U packet may be transmitted to the UE’s gNB 111, and based on the TNL information, the WAB-MT 112 in the WAB node 110 configures the DL packet filter or rule to be used in the WAB’s UPF 150 for traffic detection and mapping. In this way, the WAB’s UPF 150 can decode the UE’s NG-U packet which is ciphered based on the configured DL packet filter or rule, and the WAB’s UPF 150 may know the destination UE and the QoS flow of the UE’s NG-U packet. Therefore, the WAB’s UPF 150 may be able to perform correct traffic detection and mapping, and the QoS for UE 120 can be guaranteed.

Fig. 5 illustrates a flowchart of an example method 500 implemented at a first network device in accordance with some other embodiments of the present disclosure. For the purpose of discussion, the method 500 will be described from the perspective of the first network device 301 (for example, WAB node 110) with reference to Fig. 3.

At block 510, the first network device 301 establishes a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device. At block 520, the first network device 301 determines a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information

In some embodiments, the first network device 301 determines the rule based on the TNL information related to the first UPF serving the terminal device, and wherein the TNL information is received from a session management function (SMF) serving the terminal device.

In some embodiments, the first network device 301 comprises a base station (BS) and a mobile termination (MT) , and the first network device 301 determines the rule by: determining, at the BS or the MT, the rule to be used for traffic detection and mapping; and transmitting, from the MT, the rule to a session management function (SMF) controlling the second UPF, via an access and mobility management function (AMF) serving the MT of the first network device.

In some embodiments, the first network device 301 further transmits to an access and mobility management function (AMF) serving the terminal device, an indication that the terminal device is communicating with the first network device, wherein the TNL information is determined at the first UPF serving the terminal device, based on the indication.

In some embodiments, the transmitting of the indication and the receiving of the TNL information are performed by the BS of the first network device. In some embodiments, the TNL information comprises at least one of the following: an internet protocol (IP) address of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; a port number of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; an outer IP address of a downlink user plane traffic related to the terminal device; a security parameters index (SPI) related to a downlink user plane traffic; a differentiated services code point (DSCP) value to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or an internet protocol version 6 (IPv6) flow label to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device.

In some embodiments, the rule comprises at least one of following: a protocol data unit (PDU) session identity (ID) ; a quality of service (QoS) flow ID; a source IP address of a downlink user plane traffic related to the terminal device; a source port number of the downlink user plane traffic related to the terminal device; an outer IP address of the downlink user plane traffic related to the terminal device; a SPI related to the downlink user plane traffic; a DSCP value of the downlink user plane traffic related to the terminal device; or an IPv6 flow label of the downlink user plane traffic related to the terminal device.

Fig. 6 illustrates a flowchart of an example method 600 implemented at a third network device in accordance with some other embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the third network device 303 (for example, UE’s SMF) with reference to Fig. 3.

At block 610, the third network device 303 receives, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device. At block 620, the third network device 303 transmits the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.

In some embodiments, the third network device 303 further receives, from the AMF, an indication that the terminal device is communicating with a first network device which functions as a relay including a base station function; and transmits to the UPF, the indication to trigger the UPF to transmit the TNL information to the first network device via the AMF.

In some embodiments, the TNL information includes at least one of following: an internet protocol (IP) address of the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; a port number of the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; an outer internet protocol (IP) address of a downlink user plane traffic related to the terminal device; a security parameters index (SPI) related to a downlink user plane traffic; a differentiated services code point (DSCP) value to be used by the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or an internet protocol version 6 (IPv6) flow label to be used by the UPF for sending a downlink user plane traffic related to the terminal device to the first network device.

Fig. 7 illustrates a flowchart of an example method 700 implemented at a fourth network device in accordance with some other embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the fourth network device 304 (for example, UE’s UPF) with reference to Fig. 3.

At block 710, the fourth network device 304 receives, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) . At block 720, the fourth network device 304 determines, based on the indication, transport network layer, (TNL) information related to a downlink user plane traffic of the terminal device. At block 730, the fourth network device 304 transmits the TNL information to the SMF.

In some embodiments, the fourth network device 304 transmits the TNL information by:transmitting, to the SMF, a N4 session establishment response or N4 session modification response that includes the TNL information.

In some embodiments, the TNL information comprises information to be used for transmitting downlink (DL) next generation user plane (NG-U) packet to a second UPF serving the MT of the first network device for performing traffic mapping. In some embodiments, the TNL information comprises at least one of the following: an internet protocol (IP) address of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; a port number of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; an outer IP address of a downlink user plane traffic related to the terminal device; a security parameters index (SPI) related to a downlink user plane traffic; a differentiated services code point (DSCP) value to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or an internet protocol version 6 (IPv6) flow label to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device.

In some embodiments, an apparatus (for example, the first network device 301) capable of performing the method 500 may comprise means for performing the respective steps of the method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some embodiments, the apparatus comprises: means for establishing a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and means for determining a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information. In some embodiments, the apparatus determines the rule based on the TNL information related to the first UPF serving the terminal device, and wherein the TNL information is received from a session management function (SMF) serving the terminal device.

In some embodiments, the apparatus comprises a base station (BS) and a mobile termination (MT) , and the apparatus determines the rule by: determining, at the BS or the MT, the rule to be used for traffic detection and mapping; and transmitting, from the MT, the rule to a session management function (SMF) controlling the second UPF, via an access and mobility management function (AMF) serving the MT of the first network device.

In some embodiments, the apparatus further comprises means for transmitting to an access and mobility management function (AMF) serving the terminal device, an indication that the terminal device is communicating with the first network device, wherein the TNL information is determined at the first UPF serving the terminal device, based on the indication.

In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 500. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

In some embodiments, an apparatus (for example, the third network device 303) capable of performing the method 600 may comprise means for performing the respective steps of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some embodiments, the apparatus comprises: means for receiving, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and means for transmitting the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.

In some embodiments, the apparatus further comprises means for receiving from the AMF, an indication that the terminal device is communicating with a first network device which functions as a relay including a base station function; and transmits to the UPF, the indication to trigger the UPF to transmit the TNL information to the first network device via the AMF.

In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 600. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

In some embodiments, an apparatus (for example, the fourth network device 304) capable of performing the method 700 may comprise means for performing the respective steps of the method 700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some embodiments, the apparatus comprises: means for receiving, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) ; and means for determining, based on the indication, transport network layer, (TNL) information related to a downlink user plane traffic of the terminal device; and means for transmitting the TNL information to the SMF.

In some embodiments, the apparatus transmits the TNL information by: transmitting, to the SMF, a N4 session establishment response or N4 session modification response that includes the TNL information. In some embodiments, the TNL information comprises information to be used for transmitting downlink (DL) next generation user plane (NG-U) packet to a second UPF serving the MT of the first network device for performing traffic mapping.

In some embodiments, the TNL information comprises at least one of the following: an internet protocol (IP) address of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; a port number of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; an outer IP address of a downlink user plane traffic related to the terminal device; a security parameters index (SPI) related to a downlink user plane traffic; a differentiated services code point (DSCP) value to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or an internet protocol version 6 (IPv6) flow label to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device.

In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 700. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

Fig. 8 is a simplified block diagram of a device 800 that is suitable for implementing embodiments of the present disclosure. The device 800 may be provided to implement the communication device, for example the terminal device 102, and the network device 101, and the network device 103 as shown in Fig. 1. As shown, the device 800 includes one or more processors 810, one or more memories 820 coupled to the processor 810, and one or more communication modules 840 coupled to the processor 810.

The communication module 840 is for bidirectional communications. The communication module 840 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network devices.

The processor 810 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The memory 820 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a read only memory (ROM) 824, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 822 and other volatile memories that may not last in the power-down duration.

A computer program 830 includes computer executable instructions that are executed by the associated processor 810. The program 830 may be stored in the ROM 824. The processor 810 may perform any suitable actions and processing by loading the program 830 into the RAM 822.

The embodiments of the present disclosure may be implemented by means of the program so that the device 800 may perform any process of the methods as discussed with reference to Figs. 5 to 7. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some embodiments, the program 830 may be tangibly contained in a computer readable medium which may be included in the device 800 (such as in the memory 820) or other storage devices that are accessible by the device 800. The device 800 may load the program 830 from the computer readable medium to the RAM 822 for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like.

Fig. 9 illustrates an example of the computer readable medium 900 in form of CD or DVD in accordance with some embodiments of the present disclosure. The computer readable medium has the program 830 stored thereon. It is noted that although the computer-readable medium 900 is depicted in form of CD or DVD, the computer-readable medium 900 may be in any other form suitable for carry or hold the program 830.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the methods 500 to 700 as described above with reference to Fig. 5 to Fig. 7. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term “non-transitory, ” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM) .

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that may be described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above may be disclosed as example forms of implementing the claims.

Claims

A first network device for communication, comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the first network device at least to perform:

establishing a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and

determining a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information.
The first network device of claim 1, wherein the determining the rule is based on the TNL information related to the first UPF serving the terminal device, and wherein the TNL information is received from a session management function (SMF) serving the terminal device.
The first network device of claim 1, wherein the first network device comprises a base station (BS) , and a mobile termination (MT) and

wherein the determining the rule comprises:

determining, at the BS or the MT, the rule to be used for traffic detection and mapping; and

transmitting, from the MT, the rule to a session management function (SMF) controlling the second UPF, via an access and mobility management function (AMF) serving the MT of the first network device.
The first network device of any of claims 2 to 3, wherein the instructions, when executed by the at least one processor, further cause the first network device to perform:

transmitting, to an access and mobility management function (AMF) serving the terminal device, an indication that the terminal device is communicating with the first network device, wherein the TNL information is determined at the first UPF serving the terminal device, based on the indication.
The first network device of claim 4, wherein the transmitting of the indication and the receiving of the TNL information are performed by the BS of the first network device.
The first network device of any of claims 1 to 5, wherein the TNL information comprises at least one of the following:

an internet protocol (IP) address of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

a port number of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

an outer IP address of a downlink user plane traffic related to the terminal device;

a security parameters index (SPI) related to a downlink user plane traffic;

a differentiated services code point (DSCP) value to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or

an internet protocol version 6 (IPv6) flow label to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device.
The first network device of any of claims 1 to 6, wherein the rule comprises at least one of following:

a protocol data unit (PDU) session identity (ID) ;

a quality of service (QoS) flow ID;

a source internet protocol (IP) address of a downlink user plane traffic related to the terminal device;

a source port number of a downlink user plane traffic related to the terminal device;

an outer IP address of a downlink user plane traffic related to the terminal device;

a security parameters index (SPI) related to a downlink user plane traffic;

a differentiated services code point (DSCP) value of a downlink user plane traffic related to the terminal device; or

an internet protocol version 6 (IPv6) flow label of a downlink user plane traffic related to the terminal device.
A third network device for communication, comprising:

at least one processor; and

at least one memory storing instructions of a session management function (SMF) , that, when executed by the at least one processor, cause the third network device at least to perform:

receiving, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and

transmitting the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.
The third network device of claim 8, wherein the instructions, when executed by the at least one processor, further cause the third network device to perform:

receiving, from the AMF, an indication that the terminal device is communicating with a first network device which functions as a relay including a base station function; and

transmitting, to the UPF, the indication to trigger the UPF to transmit the TNL information to the first network device via the AMF.
The third network device of claim 8, wherein the TNL information includes at least one of following:

an internet protocol (IP) address of the UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

a port number of the UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

an outer internet protocol (IP) address of a downlink user plane traffic related to the terminal device;

a security parameters index (SPI) related to a downlink user plane traffic;

a differentiated services code point (DSCP) value to be used by the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or

an internet protocol version 6 (IPv6) flow label to be used by the UPF for sending a downlink user plane traffic related to the terminal device to the first network device.
A fourth network device for communication, comprising:

at least one processor; and

at least one memory storing instructions of a first user plane function (UPF) that, when executed by the at least one processor, cause the fourth network device at least to perform:

receiving, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) ;

determining, based on the indication, transport network layer, (TNL) information related to a downlink user plane traffic of the terminal device; and

transmitting the TNL information to the SMF.
The fourth network device of claim 11, wherein the transmitting the TNL information comprises:

transmitting, to the SMF, a N4 session establishment response or N4 session modification response that includes the TNL information.
The fourth network device of claim 11 or 12, wherein the TNL information comprises information to be used for transmitting downlink (DL) next generation user plane (NG-U) packet to a second UPF serving the MT of the first network device for performing traffic mapping.
The fourth network device of any of claims 11 to 13, wherein the TNL information comprises at least one of the following:

an internet protocol (IP) address of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

a port number of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

an outer IP address of a downlink user plane traffic related to the terminal device;

a security parameters index (SPI) related to a downlink user plane traffic;

a differentiated services code point (DSCP) value to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or

an internet protocol version 6 (IPv6) flow label to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device.
A method for communication performed by a first network device, comprising:

establishing a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and

determining a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information.
The method of claim 15, wherein the determining the rule is based on the TNL information related to the first UPF serving the terminal device, and wherein the TNL information is received from a session management function (SMF) serving the terminal device.
The method of claim 15, wherein the first network device comprises a base station (BS) , and a mobile termination (MT) and

wherein the determining the rule comprises:

determining, at the BS or the MT, the rule to be used for traffic detection and mapping; and

transmitting, from the MT, the rule to a session management function (SMF) controlling the second UPF, via an access and mobility management function (AMF) serving the MT of the first network device.
The method of any of claims 16 to 17, further comprising:

transmitting, from the first network device to an access and mobility management function (AMF) serving the terminal device, an indication that the terminal device is communicating with the first network device, wherein the TNL information is determined at the first UPF serving the terminal device, based on the indication.
The method of claim 18, wherein the transmitting of the indication and the receiving of the TNL information are performed by the BS of the first network device.
The method of any of claims 15 to 19, wherein the TNL information comprises at least one of the following:

an internet protocol (IP) address of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

a port number of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

an outer IP address of a downlink user plane traffic related to the terminal device;

a security parameters index (SPI) related to a downlink user plane traffic;

a differentiated services code point (DSCP) value to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or

an internet protocol version 6 (IPv6) flow label to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device.
The method of any of claims 15 to 20, wherein the rule comprises at least one of following:

a protocol data unit (PDU) session identity (ID) ;

a quality of service (QoS) flow ID;

a source internet protocol (IP) address of a downlink user plane traffic related to the terminal device;

a source port number of a downlink user plane traffic related to the terminal device;

an outer IP address of a downlink user plane traffic related to the terminal device;

a security parameters index (SPI) related to a downlink user plane traffic;

a differentiated services code point (DSCP) value of a downlink user plane traffic related to the terminal device; or

an internet protocol version 6 (IPv6) flow label of a downlink user plane traffic related to the terminal device.
A method for communication performed by a third network device, comprising:

receiving, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and

transmitting the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.
The method of claim 22, further comprising:

receiving, from the AMF, an indication that the terminal device is communicating with a first network device which functions as a relay including a base station function; and

transmitting, to the UPF, the indication to trigger the UPF to transmit the TNL information to the first network device via the AMF.
The method of claim 22, wherein the TNL information includes at least one of following:

an internet protocol (IP) address of the UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

a port number of the UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

an outer internet protocol (IP) address of a downlink user plane traffic related to the terminal device;

a security parameters index (SPI) related to a downlink user plane traffic;

a differentiated services code point (DSCP) value to be used by the UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or

an internet protocol version 6 (IPv6) flow label to be used by the UPF for sending a downlink user plane traffic related to the terminal device to the first network device.
A method for communication performed by a fourth network device, comprising:

receiving, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) ;

determining, based on the indication, transport network layer, (TNL) information related to a downlink user plane traffic of the terminal device; and

transmitting the TNL information to the SMF.
The method of claim 25, wherein the transmitting the TNL information comprises:

transmitting, to the SMF, a N4 session establishment response or N4 session modification response that includes the TNL information.
The method of claim 25 or 26, wherein the TNL information comprises information to be used for transmitting downlink (DL) next generation user plane (NG-U) packet to a second UPF serving the MT of the first network device for performing traffic mapping.
The method of any of claims 25 to 27, wherein the TNL information comprises at least one of the following:

an internet protocol (IP) address of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

a port number of the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device;

an outer IP address of a downlink user plane traffic related to the terminal device;

a security parameters index (SPI) related to a downlink user plane traffic;

a differentiated services code point (DSCP) value to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device; or

an internet protocol version 6 (IPv6) flow label to be used by the first UPF for sending a downlink user plane traffic related to the terminal device to the first network device.
An apparatus, comprising:

means for establishing a protocol data unit (PDU) session using a first user plane function (UPF) serving a terminal device connected with the first network device; and

means for determining a rule to be used for traffic detection and mapping at a second UPF used for wireless access backhauling for the first network device, based on transport network layer (TNL) information.
An apparatus, comprising:

means for receiving, from a user plane function (UPF) serving a terminal device connected with a first network device, transport network layer (TNL) information related to a downlink user plane traffic of the terminal device; and

means for transmitting the TNL information to the first network device via an access and mobility management function (AMF) serving the terminal device.
An apparatus, comprising:

means for receiving, from a session management function (SMF) , an indication that a terminal device is communicating with a first network device which functions as a relay including a base station function and a mobile termination (MT) ;

means for determining, based on the indication, transport network layer, (TNL) information related to a downlink user plane traffic of the terminal device; and

means for transmitting the TNL information to the SMF.
A non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus at least to perform the method according to any of claims 15 to 28.