Method and apparatus for managing session by considering backhaul information in wireless communication system

Abstract

The disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting a higher data rate beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). An access network (AN) node of a wireless communication system according to an embodiment of the disclosure can manage a session by using backhaul information, which can include the steps of: selecting an access and mobility management function (AMF) when a registration request message is received from a user equipment (UE); selecting one of candidate transport network layer associations (TNLAs) for the selected AMF by considering a type of a backhaul network of a control plane; transmitting an initial UE message to the selected AMF by using the selected TNLA; and performing a registration procedure of the UE when a selected TNLA response signal is received from the selected AMF, wherein the candidate TNLAs can include a low earth orbit (LEO) and / or a geo-synchronous earth orbit (GEO).

Description

Technical Field

[0001] This disclosure relates to a method and apparatus for session management in a wireless communication system that takes backhaul information into account. Background Technology

[0002] To meet the increased demand for wireless data services since the deployment of 4G communication systems, efforts have been made to develop improved 5G or near-5G communication systems. Therefore, 5G or near-5G communication systems are also referred to as "super 4G networks" or "post-LTE systems".

[0003] 5G communication systems are considered to be implemented in higher frequency (mmWave) bands (e.g., the 60GHz band) to achieve higher data rates. To reduce radio wave propagation loss and increase transmission distance, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO technologies are discussed in 5G communication systems.

[0004] In addition, in 5G communication systems, system network improvements are being developed based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, cooperative multipoint (CoMP), and receiver interference cancellation.

[0005] In 5G systems, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) have been developed as advanced coding modulation (ACM), as well as filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies.

[0006] Compared to existing 4G systems, 5G systems are considering supporting a wide range of services. For example, the most representative services include enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC), massive machine-type communication (mMTC), and evolved multimedia broadcast / multicast service (eMBMS). Furthermore, a system providing URLLC services can be called an URLLC system, and a system providing eMBB services can be called an eMBB system. Additionally, the terms "service" and "system" are used interchangeably.

[0007] Unlike existing 4G systems, URLLC service is a new service considered in 5G systems, and it requires ultra-high reliability (e.g., approximately 10) compared to other services. -5The conditions include low packet error rate and low latency (e.g., approximately 0.5 milliseconds). To meet such stringent requirements, URLLC services would need to apply a shorter Transmission Time Interval (TTI) than eMBB services, and various operational methods using this TTI are being considered.

[0008] The internet, as a human-centric network for generating and consuming information, is now evolving into the Internet of Things (IoT), in which distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), a combination of IoT technology and big data processing technology connected to cloud servers, has emerged. Because IoT implementation requires technological elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology, sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC) have recently been studied.

[0009] Such an IoT environment can provide intelligent internet technology services that create new value for human life by collecting and analyzing data generated between connected things. Through the integration and combination of existing information technology (IT) with various industrial applications, IoT can be applied to a wide range of fields, including smart homes, smart buildings, smart cities, smart or connected cars, smart grids, healthcare, smart appliances, and advanced medical services.

[0010] Consistent with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine-type communication (MTC), and machine-to-machine (M2M) communication can be implemented using beamforming, MIMO, and array antennas. The application of cloud radio access networks (RAN), as a big data processing technology, can also be seen as an example of the convergence between 5G and IoT technologies.

[0011] With advancements in satellite communication technology, efforts are underway to integrate this technology, which has only been introduced to a limited extent, into mobile communication networks. In particular, research is being conducted on introducing satellite links into the backhaul portion (the section between the Radio Access Network (RAN) and the core network) that is typically connected via fiber-optic-based wired links. Summary of the Invention

[0012] Technical issues

[0013] Within the 3rd Generation Partnership Project (3GPP), standardization is underway for various scenarios integrating mobile communications and fifth-generation (5G) technologies into 5G communication systems. Specifically, methods for introducing satellite connectivity in the backhaul portion connecting the radio access network (RAN) and the core network are being standardized. Satellite connectivity offers various advantages, such as reduced costs associated with establishing wired links (e.g., installing embedded fiber optic cables). On the other hand, applying satellite technology to the backhaul portion can lead to issues such as variable network conditions or high latency, and necessitates additional mechanisms to meet the Quality of Service (QoS) requirements of 5G systems.

[0014] To address this issue, research conducted within 3GPP has discussed User Plane Function (UPF) device selection techniques that consider network latency of Session Management Function (SMF) devices during session creation. However, because the discussed techniques do not consider the existence of satellite backhaul links in the Access Network (AN) used for UE access, a problem arises where even UEs requesting sessions via an AN with only wired backhaul links are forced to consider UPF latency when performing UPF selection. Therefore, a technique is needed to provide the SMF with AN backhaul connection information during session processing, thereby enabling the SMF to consider latency only under specific circumstances when performing UPF selection.

[0015] Furthermore, because the discussed techniques do not consider whether a satellite backhaul network exists between the AN accessed by the UE and the core network, whether the control plane backhaul network used for the N2 interface between the AN and AMF, and whether the user plane backhaul network used for the N3 interface between the AN and UPF uses the same backhaul network, the following problems arise: During Protocol Data Unit (PDU) session establishment, considering the latency occurring in the backhaul network, the UPF cannot be selected, and the N3 tunnel information cannot be determined. Therefore, it is necessary to determine the type of backhaul network, select a UPF that meets QoS requirements due to latency occurring in the backhaul network, and implement techniques to avoid N3 tunnel information allocation failures during the registration and session establishment processes.

[0016] The technical problems to be solved in this disclosure are not limited to those described above, and those skilled in the art to which this disclosure pertains will clearly understand from the following description other technical problems not mentioned.

[0017] Problem Solution

[0018] According to embodiments of this disclosure, a session management method using backhaul information in an access network (AN) node of a wireless communication system may include: selecting an Access and Mobility Management Function (AMF) upon receiving a registration request message from a User Equipment (UE); selecting a TNLA from candidate Transport Network Layer Associations (TNLAs) for the selected AMF by considering the type of backhaul network in the control plane; sending an initial UE message to the selected AMF using the selected TNLA; and performing a UE registration process upon receiving a selected TNLA response signal from the selected AMF.

[0019] According to embodiments of this disclosure, an access network (AN) node device for managing sessions using backhaul information in a wireless communication system may include: a transceiver configured to communicate with a specific node of the wireless communication system and to communicate with a user equipment (UE); a memory configured to store session-related information; and at least one processor configured to perform the following operations:

[0020] When a registration request message is received from the UE via the transceiver, an Access and Mobility Management Function (AMF) is selected. The type of backhaul network in the control plane is considered for the selected AMF. A TNLA is selected from the candidate Transport Network Layer Associations (TNLAs). An initial UE message is sent to the selected AMF via the transceiver using the selected TNLA. The UE registration process is performed when a selected TNLA response signal is received from the selected AMF.

[0021] Candidate TNLAs may include at least one of low Earth orbit (LEO) and geosynchronous Earth orbit (GEO).

[0022] Beneficial effects of the present invention

[0023] According to this disclosure, when a User Equipment (UE) creates an AN request session connected via one or more satellite backhaul links in a 3GPP 5G system, the Access and Mobility Management (AMF) device can effectively determine whether a QoS-restricted backhaul link (e.g., a satellite link) exists. Furthermore, based on this determination, the SMF can consider network conditions to perform an effective UPF selection.

[0024] According to this disclosure, when a UE requests registration and PDU session establishment with the core network via an AN connected through one or more backhaul networks in a 3GPP 5G system, the AMF can effectively determine whether to use a QoS-restricted backhaul network (e.g., a satellite backhaul network). In this way, the SMF can consider network conditions to select an effective UPF and configure the user data path accordingly.

[0025] The effects that can be obtained in this disclosure are not limited to those described above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. Attached Figure Description

[0026] Figure 1 This is a diagram illustrating a scenario where satellite backhaul is used in an existing 3GPP 5G system.

[0027] Figure 2 This is a diagram illustrating a method by which the Access and Mobility Management (AMF) according to an embodiment of the present disclosure enables the Session Management Function (SMF) to perform selection of the User Plane Function (UPF) by taking backhaul connection information into account during the Protocol Data Unit (PDU) session creation process.

[0028] Figure 3 This is a diagram illustrating a method for registering a user plane function (UPF) with a backhaul connection having quality of service (QoS) limitations at a network repository function (NRF) according to an embodiment of this disclosure.

[0029] Figure 4 This is a diagram illustrating a method by which a Session Management Function (SMF) selects a User Plane Function (UPF) via a Network Repository Function (NRF) during the creation of a Protocol Data Unit (PDU) session via an access network (AN) with a backhaul connection having Quality of Service (QoS) limitations, according to an embodiment of the present disclosure.

[0030] Figure 5 This is a diagram illustrating a method by which a User Plane Function (UPF) with a backhaul connection having Quality of Service (QoS) limitations, according to an embodiment of the present disclosure, makes a request to the Session Management Function (SMF) to establish an association for N4 (the interface between the SMF and the UPF).

[0031] Figure 6 This is a diagram illustrating a method by which a User Plane Function (UPF) with a backhaul connection having Quality of Service (QoS) limitations, according to an embodiment of the present disclosure, performs a request for an N4 (interface between the SMF and UPF) association update to the Session Management Function (SMF).

[0032] Figure 7 This is a diagram illustrating a scenario in a 3GPP 5G system where terrestrial and satellite backhaul networks are applied to the control plane and user plane according to embodiments of the present disclosure.

[0033] Figure 8 This is a diagram illustrating the relationship between the transport network layer association (TNLA or TNL association) and the backhaul network used in the control plane of a 3GPP 5G system according to an embodiment of the present disclosure.

[0034] Figure 9 This is a diagram illustrating a method by which the RAN and AMF perform TNL association selection during the registration process based on the characteristics of the backhaul network used for the control plane, according to an embodiment of the present disclosure.

[0035] Figure 10 This is a diagram illustrating a PDU session establishment process that takes into account the characteristics of a backhaul network according to an embodiment of the present disclosure.

[0036] Figure 11 This is a diagram illustrating the structure of a UE according to an embodiment of the present disclosure.

[0037] Figure 12 This is a diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0038] Figure 13 This is a diagram illustrating the structure of a network entity according to an embodiment of the present disclosure. Detailed Implementation

[0039] The operating principles of this disclosure will be described in detail below with reference to the accompanying drawings. In the following description of this disclosure, detailed descriptions of known functions or configurations incorporated herein will be omitted where such inclusion would unnecessarily obscure the subject matter of the invention. The terminology described below is defined in consideration of the functions in this disclosure and may vary depending on the user, the user's intention, or habit. Therefore, the definition of terminology should be based on the entire contents of this specification. In the following description, for convenience, terms for identifying access nodes, referring to network entities, referring to messages, referring to interfaces between network entities, referring to various identification information, etc., are used illustratively. Therefore, this disclosure is not limited to the terminology used below, and other terms referring to subjects with equivalent technical meanings may be used.

[0040] In the following description, for ease of description, the terms and names defined in the 3GPP LTE standard will be used to describe this disclosure. However, this disclosure is not limited to these terms and names and can be applied in the same manner to systems conforming to other standards. Furthermore, in this disclosure, a particular network function can be implemented using a single network entity or an instance. When implemented using a network entity, for example, a server can be implemented to perform a network function. Alternatively, a server can be constructed to include two or more network entities. In this case, the network entities can perform the same function or perform different functions. For example, a server can include two or more AMFs. In another example, a server can include two or more SMFs. In this case, each network entity performing the same function can be implemented using an instance.

[0041] Furthermore, one server can cover one region, and different servers can cover different regions. Therefore, the same network entity can also be implemented on servers located in different regions.

[0042] In another example, a network entity can be implemented using two or more servers.

[0043] Figure 1 This is a diagram illustrating a scenario where satellite backhaul is used in an existing 3GPP 5G system.

[0044] A 5G system consists of an access network (AN) that provides radio access to terminals (e.g., user equipment (UE)) and the following main network equipment: Access and Mobility Management Function (AMF), Session Management Function (SMF), User Plane Function (UPD), and Policy Control Function (PCF). The AMF, SMF, and PCF reside in the control plane. The AMF performs functions that manage the mobility of each UE, the SMF performs UE session management functions and UPF management functions through the N4 interface, and the PCF provides UE policy control functions. Meanwhile, the UPF resides in the user plane (i.e., the plane through which user data passes) and performs functions that transmit user data. Additionally, the AN provides radio access to the UE, transmits the UE's control plane data to the AMF (here, the interface between the AN and AMF is referred to as N2), and transmits the UE's user plane data to the UPF (here, the interface between the AN and UPF is referred to as N3). The PDU session creation procedure is used to create a path for the UE to transmit user data. The PDU session creation request message sent by the UE to the AN is delivered to the SMF through the AN and AMF. After receiving the relevant policy from the PCF, the SMF can select the UPF. When selecting the UPF, a query message can be sent to the Network Repository Function (NRF) device to select the UPF. Subsequently, operations are performed to configure the paths from the UE's user plane to the AN and UPF, and when the operations are complete, the UE is notified that the PDU session creation is complete.

[0045] Meanwhile, in 5G systems, backhaul refers to the system that connects data collected from a user's internet access device (such as a UE) to the backbone network. Backhaul connections used to connect UPFs and gNBs (next-generation node Bs, gNodeBs, base stations, or ANs) or UPFs can have the following two states:

[0046] 1) In situations where QoS restrictions exist (e.g., backhaul using satellite connections), and

[0047] 2) In the absence of QoS restrictions (e.g., using a wired backhaul).

[0048] refer to Figure 1 This disclosure presents three scenarios for applying existing satellite backhaul. It aims to address typical issues with backhaul connections in situations where QoS limitations exist (e.g., backhaul using satellite connections).

[0049] The first scenario 1-10 can be the case where the backhaul connection between AN 1-12 and UPF 1-17 and the backhaul connection between AN 1-12 and AMF 1-13 use only one type of backhaul connection.

[0050] The second scenario 1-20 can be a case where AN 1-12 has various types of backhaul connections with UPF 1-27a, UPF 1-27b and UPF 1-27c.

[0051] Scenario 3, 1-30, illustrates cases where UPF 1-37a, UPF 1-37b, and UPF 1-37c have different types of backhaul connections than other UPF 1-37d and UPF 1-37e.

[0052] The existing technology proposed in 3GPP for scenario 1-10 involves delivering information about the type of satellite used for the backhaul connection (e.g., Low Earth Orbit (LEO), Medium Earth Orbit (MEO), Geosynchronous Earth Orbit (GEO)) to AMF 1-13 when the backhaul connection of AN 1-12 is satellite 1-16. During session creation, AMF 1-13 can determine the satellite type (interface between gNB and initial UPF) of N3 used for session passage (or formation) based on the received information and send it to SMF 1-14. Based on the satellite type and information in the UE's session creation message, SMF 1-14 can determine whether to reject or accept the creation request.

[0053] In scenarios 1-20 and 1-30, unlike scenario 1-10, AN 1-22 and AN 1-32 can be connected to multiple UPFs 1-27a, 1-27b, 1-27c, 1-37a, 1-37b, and 1-37c via different backhaul connection types. Furthermore, the connected UPF 1-37a can also be connected to other UPFs 1-37d and 1-37e via different backhaul connection types. In this case, the ability to select the appropriate UPF by taking into account information such as latency is essential during PDU session creation.

[0054] To this end, in the prior art proposed by 3GPP, during the PDU session creation process, the UPF can measure the latency (hereinafter referred to as QoS constraints) of the connected entity (e.g., AN or UPF) and notify it to SMF 1-24 or SMF 1-34, and SMF 1-24 or SMF 1-34 can select the UPF based on the QoS constraints. Therefore, although methods have been proposed for SMF 1-24 or SMF 1-34 to select the UPF considering latency, the problem is that for all PDU session creation requests, the QoS constraint information of all UPFs must be taken into account to perform UPF selection. For example, the problem is that even when a session request is made through an AN with only a wired backhaul connection type, latency must be unnecessarily considered when performing UPF selection. Furthermore, the problem is that when a session request is made through an AN with a satellite backhaul connection, the latency of all UPFs must be considered, rather than the latency of the UPF connected to the corresponding AN, when performing UPF selection.

[0055] Figure 2 This is a diagram illustrating a method by which the AMF, according to an embodiment of the present disclosure, enables the SMF to perform UPF selection by taking backhaul connection information into account during the PDU session creation process.

[0056] User Equipment (UE) 2-01 can send a PDU session establishment request to AMF 2-03 (step 2-07). Upon receiving the PDU session establishment request message from UE 2-01 (step 2-07), Radio Access Network (RAN) 2-02 can determine whether a backhaul with QoS restrictions exists in its backhaul connection, and if a backhaul with QoS restrictions exists, it includes backhaul-related information in the NAS transmission message. At this time, RAN 2-02 can include an indicator (QoS restriction indicator) indicating the existence of at least one backhaul connection with QoS restrictions or information for each backhaul connection (e.g., satellite category information for each user plane interface of the AN, latency information for each user plane interface of the AN) in the backhaul-related information and send it to AMF 2-03 (step 2-08).

[0057] AMF 2-03 can determine whether AN 2-02, accessed by UE 2-01, has a QoS-restricted backhaul connection (step 2-09). AMF 2-03 can determine that AN 2-02 has a QoS-restricted backhaul connection in the following situations: If the message in step 2-08 contains backhaul-related information, AMF 2-03 can determine that a QoS-restricted backhaul connection exists. If information regarding the existence of QoS-restricted backhaul connections for each Tracking Area Identifier (TAI) is configured in AMF 2-03, AMF 2-03 can determine the existence of a QoS-restricted backhaul connection based on the TAI value from AN 2-02 and the configured information. Alternatively, it can be determined through local configuration (step 2-09).

[0058] If it is determined in step 2-09 that a backhaul connection with QoS restrictions exists, AMF 2-03 may include a QoS restriction indicator in the SM context creation request message sent to SMF2-04 (step 2-10).

[0059] SMF2-04 can utilize the Point Coordination Function (PCF) 2-05 to perform SM policy establishment (step 2-11).

[0060] SMF 2-04 may consider the QoS restrictions or satellite category of UPF 2-08 to determine whether to perform UPF selection (step 2-12). In this case, if the message from step 2-10 contains a QoS restriction indicator, SMF 2-04 can determine that a backhaul connection with QoS restrictions exists and that UPF selection should be performed taking into account either the QoS restrictions or the satellite category (step 2-12). Alternatively, if the TAI value from the message from step 2-10 indicates that a backhaul connection with QoS restrictions exists in AMF 2-03, SMF 2-04 can determine that a backhaul connection with QoS restrictions exists and that UPF selection should be performed taking into account either the QoS restrictions of the UPF or the satellite category (step 2-12).

[0061] If SMF 2-04 determines in step 2-12 that the QoS limitations (e.g., latency, etc.) or satellite category of each Layer 3 (L3) interface (e.g., Internet Protocol (IP) interface) of UPF 2-08 should be considered when performing UPF selection, then SMF 2-04 may perform UPF selection by considering the QoS limitations or satellite category information of the UPF (step 2-13).

[0062] After that, the remaining PDU session creation process (step 2-14) can be performed between UE 2-01 and UPF 2-08.

[0063] Figure 3This is a diagram illustrating a method for registering a UPF3-01 with a QoS-restricted backhaul connection at NRF 3-02 according to an embodiment of this disclosure.

[0064] If a backhaul interface using a satellite connection exists, the UPF 3-01 can include in the NF profile used for registration with the NRF: a QoS restriction list (i.e., latency information for each connected UPF when the UPF 3-01 is connected to other UPFs in the user plane via L3 communication), which consists of QoS restrictions (e.g., latency) for each of its L3 interfaces (e.g., IP interfaces); a satellite category list (i.e., satellite category information for each connected UPF when the UPF is connected to other UPFs in the user plane via L3 communication), which consists of satellite categories (e.g., LEO, MEO, GEO) for each of its L3 interfaces; and other backhaul interface related information for each of its L3 interfaces. In this case, the UPF 3-01 can include some or all of the above parameters (QoS restriction list, satellite category list, and other backhaul interface related information). That is, it can send the QoS restriction list to the SMF (Signature Provider Function). Figure 3 The UPF 3-01 (not shown) can include a list of QoS restrictions in the NF profile sent to NRF 3-02. Additionally, it supports sending a list of satellite categories to the SMF (…). Figure 3 The UPF 3-01 (not shown) can include a list of satellite categories in the NF profile sent to NRF 3-02, and the UPF 3-01 can also include the corresponding other backhaul interface information in the NF profile sent to NRF 3-02 (step 3-03).

[0065] NRF 3-20 sends a response message to UPF 3-01 (step 3-04).

[0066] Figure 4 This is a diagram illustrating a method by which an SMF 4-01 selects a UPF via an NRF 4-02 during the creation of a PDU session via an AN with a backhaul connection having QoS restrictions, according to an embodiment of the present disclosure.

[0067] If SMF 4-01 determines during PDU session creation that the AN accessed by the UE has a backhaul connection with one or more QoS restrictions, and if SMF 4-01 intends to select a UPF with a backhaul connection to the AN without QoS restrictions, then SMF 4-01 may include the UPF with the non-QoS-restricted backhaul connection in the query message and send it to NRF 4-02 in step 4-03. Additionally, when it is desired to restrict the UPF candidate group to UPFs connected to the AN, SMF 4-01 may include a TAI corresponding to the UE's location information and send it to NRF 4-02.

[0068] If SMF 4-01 determines during PDU session creation that the AN accessed by the UE has a backhaul connection with one or more QoS restrictions, and if SMF 4-01 expects to select a UPF with a backhaul connection to the AN that has a latency lower than the required minimum backhaul latency, then SMF 4-01 may include the required minimum backhaul latency and send it to NRF 4-02. Additionally, when it is desired to limit the UPF candidate group to UPFs connected to the AN, SMF 4-01 may include a TAI corresponding to the UE's location information and send it to NRF 4-02.

[0069] If SMF 4-01 determines during PDU session creation that the AN accessed by the UE has a backhaul connection with one or more QoS restrictions, and if SMF 4-01 expects to select a UPF with a backhaul connection to a specific satellite class of the AN, then SMF 4-01 may include the satellite class and send it to NRF 4-02. Additionally, when it is desired to restrict the UPF candidate group to UPFs connected to the AN, SMF 4-01 may include a TAI corresponding to the UE's location information and send it to NRF 4-02 (step 4-03).

[0070] When a TAI and a UPF with a non-QoS-restricted backhaul connection are present in the message sent by SMF 4-01 in step 4-03, NRF 4-02 does not include information about those UPFs with QoS restrictions on the interfaces of the UPFs that have interfaces corresponding to the TAI in the response message.

[0071] When a TAI and a required minimum backhaul latency are present in the message sent by SMF 4-01 in step 4-03, NRF 4-02 does not include information in the response message about those UPFs whose latency (i.e., QoS limit) in the interface of the UPF with the interface corresponding to the TAI is higher than the required minimum backhaul latency.

[0072] When TAI and satellite category are present in the message sent by SMF 4-01 in step 4-03, NRF 4-02 does not include information about those UPFs that use satellite category in the interface among the UPFs that have the interface corresponding to TAI in the response message.

[0073] NRF 4-02 sends a response message using at least one and / or a combination of the above schemes (step 4-04).

[0074] Figure 5 This is a diagram illustrating a method by which a UPF 5-01 with a QoS-restricted backhaul connection executes a request to an SMF 5-02 to establish an association for N4 (the interface between the SMF and the UPF) according to an embodiment of the present disclosure.

[0075] In the presence of a backhaul interface using satellite connectivity, UPF 5-01 includes in its message requesting the establishment of an N4 association with SMF 5-02 a list of satellite categories (e.g., LEO, MEO, GEO) for each of its L3 interfaces, as well as other backhaul interface information for each of its L3 interfaces (i.e., information on each satellite category of all connected UPFs when the UPF connects to other UPFs in the user plane via L3 communication). In this case, UPF 5-01 may include some or all of the parameters described above (step 5-03).

[0076] SMF sends a response message corresponding to the received message (step 5-04).

[0077] Figure 6 This is a diagram illustrating a method by which a UPF 6-01 with a QoS-restricted backhaul connection performs a request for an association update of N4 (the interface between the SMF and the UPF) to an SMF 6-02 according to an embodiment of the present disclosure.

[0078] When using satellite connectivity to detect the backhaul interface, UPF 6-01 includes the following in the N4 association update message sent to SMF 6-02: a satellite category list (i.e., information on each satellite category of all connected UPFs when the UPF connects to other UPFs in the user plane via L3 communication), which consists of the satellite category (e.g., LEO, MEO, GEO) of each of its L3 interfaces; and other backhaul interface related information for each of its L3 interfaces. In this case, the UPF may include some or all of the above parameters (step 6-03).

[0079] SMF 6-02 sends a response message (step 6-04).

[0080] Figure 7This is a diagram illustrating a scenario in which terrestrial and satellite backhaul networks are applied to the control plane and user plane of a 3GPP 5G system according to embodiments of the present disclosure.

[0081] Figure 7 Corresponding to Figure 1 The first to third scenarios shown are expanded. First, in Figure 7 In the diagram, UE 7-01, AN7-02, UPF 7-21, UPF 7-22 and UPF 7-23, AMF 7-03, SMF 7-04 and PCF 7-05 are shown as entities. (Refer to...) Figures 8 to 10 The embodiments described in this disclosure may be based on Figure 7 The scenario is illustrated. In a 3GPP 5G system, the backhaul network can provide connectivity between the RAN and the core network, and different types of communication protocols can be applied to both the control plane and the user plane. As such a backhaul network, Figure 7 Exemplary examples are shown: ground backhaul network 7-11, geostationary Earth orbit (GEO) satellite backhaul network 7-12, and low Earth orbit (LEO) satellite backhaul network 7-13. Backhaul networks can be further subdivided into low Earth orbit (LEO), medium Earth orbit (MEO), and geostationary Earth orbit (GEO) corresponding to high Earth orbit, as described in the first to third scenarios above. Furthermore, the backhaul network used in the control plane and the backhaul network used in the user plane can be the same or different. AN 7-02 can determine which backhaul network to use. In the case of the control plane, AN 7-02 can determine which backhaul network to use during the registration process, and in the case of the user plane, AN 7-02 can determine which backhaul network to use during the PDU session establishment process. For example, when initiating a control plane connection to AMF 7-03 via the N2 interface during registration, AN 7-02 can select GEO satellite backhaul network 7-12 (…). Figure 7 The return network in the middle (_02), and in this case, it will be greater than the ground return network 7-11 ( Figure 7 The transmission delay of the backhaul network (_01) in the middle. Subsequently, when the UPF and AN 7-02 allocate tunnel information for the N3 interface during the PDU session establishment process, supporting the GTP-U path via the GEO satellite backhaul network, the control plane and user plane begin using the same backhaul network. Additionally, if support for the backhaul network via terrestrial backhaul network 7-11 is allocated... Figure 7 The backhaul network in the middle (_01) or LEO satellite backhaul network 7-13 ( Figure 7If the tunnel information of the GTP-U path in the backhaul network (_03) is obtained, then the control plane and user plane will start using different backhaul networks. When different types of backhaul networks are used in the control plane and user plane, the system can adaptively respond based on the location of each NF constituting the core network and the service status of the backhaul network.

[0082] Figure 8 This is a diagram illustrating the relationship between the transport network layer association (TNLA or TNL association) and the backhaul network used in the control plane of a 3GPP 5G system according to an embodiment of the present disclosure.

[0083] exist Figure 8 In this configuration, UE 8-01 is connected to RNA 8-02, and RNA 8-02 is connected to AMF 8-21 via different backhaul networks 8-11, 8-12, and 8-13. In this case, the control plane connection between one RAN 8-02 and one AMF 8-21 can consist of one or more TNL associations. Figure 8 Exemplary examples show that the first backhaul network 8-11 has three different TNLAs (TNLA_01, TNLA_02, TNLA_03), the second backhaul network 8-12 has two different TNLAs (TNLA_04, TNLA_05), and the third backhaul network 8-13 has two different TNLAs (TNLA_06, TNLA_07).

[0084] During the process of initiating an N3 interface with a specific AMF 8-21, RAN 8-02 can select one of the TNL associations (candidate TNL associations) to connect to AMF 8-21. When RAN 8-02 receives a message to be delivered to AMF 8-21 from UE 8-01, it can send the message to AMF 8-21 through the selected TNL association. AMF 8-21 can determine whether to continue using the TNL association selected by RAN 8-02 as the N3 interface or to change it to another TNL association. If it is determined to change to another TNL association, AMF 8-21 can send the message to be delivered to UE 8-01 to RAN 8-02 through the selected TNL association. If AMF 8-21 does not find a suitable connection in the TNL association with RAN 8-02, AMF 8-21 can select another suitable AMF, notify RAN 8-02, and initiate a rerouting procedure so that the message to be delivered to UE 8-01 can be sent through the selected other AMF. In addition, when RAN 8-02 selects TNL associations, it can provide a method that considers (1) availability and (2) weighting factors of candidate TNL associations.

[0085] According to embodiments of this disclosure, when selecting a TNL association for RAN 8-02, a method can be provided to further consider the backhaul network type of candidate TNL associations (3). RAN 8-02 can select a TNL association based on some or all of a combination of (1), (2), and (3), and notify AMF 8-21 of the backhaul network type of the selected TNL association. For example, in Figure 8 When RAN 8-02 selects TNLA_04 in the second backhaul network, RAN 8-02 can notify AMF 8-21 that the selected TNLA uses a satellite backhaul network, thus resulting in greater latency than a terrestrial backhaul network. When determining whether another TNLA is more suitable than TNLA_04 selected by RAN 8-02, AMF 8-21 can select TNLA_05 using the same backhaul network, or select TNLA_01 using a different backhaul network, to change the NGAP UE-TNLA-binding, based on information about the backhaul network type notified by RAN 8-02. AMF 8-21 and other network function (NF) devices in the core network can choose to associate with the TNL of the corresponding backhaul network to select a backhaul network with lower or higher latency based on the type of backhaul network, considering factors such as the resource distribution (load balancing) of the N3 interface or the importance of the NAS messages to be delivered to the UE.

[0086] Figure 9 This is a diagram illustrating a method by which the RAN and AMF perform TNL association selection during the registration process based on the characteristics of the backhaul network used for the control plane, according to an embodiment of the present disclosure.

[0087] In steps 9-11, RAN 9-02 can perform an establishment procedure to provide information about the radio interface of the UE located within the radio coverage area of ​​RAN 9-02 to the AMF at a location (physical and / or logical location) on the network that can connect to RAN 9-02. NG establishment assumes activation of a candidate TNL association between RAN 9-02 and AMF 9-03. During the NG establishment step, RAN 9-02 can transmit information about the radio portion between UE 9-01 and RAN 9-02 to AMF 9-03, such as the global RAN node ID, supported tracking areas (TAs), broadcast PLMN list, radio access technology (RAT) information, etc. When configured to allow only specific types of backhaul networks to connect to the TAs covered by RAN 9-02, RAN 9-02 can transmit information about the type of the corresponding backhaul network to AMF 9-03.

[0088] In step 9-12, UE 9-01 can send a registration request message to RAN 9-02.

[0089] In step 9-13, RAN 9-02 can select AMF.

[0090] In steps 9-14, RAN 9-02 can select one of the candidate TNL associations for the AMF selected in step 9-13. In this case, RAN 9-02 can perform the selection considering the type of backhaul network through which the candidate TNL association passes. If the selected TNL association uses a backhaul network with greater latency characteristics, RAN 9-02 can determine whether to notify AMF 9-03. This determination may refer to the Single Network Slice Selection Assist Information (S-NSSAI) requested by the UE, the corresponding RAT information or TA information of RAN 9-02, the location of UE 9-01, etc.

[0091] In steps 9-15, RAN 9-02 can send the initial UE message to AMF 9-03 via the TNL association selected in step 9-14. When, according to the determination in step 9-14, the backhaul network can use satellite or a backhaul network with high latency (or even not satellite), the initial UE message may include a satellite backhaul indication. A satellite backhaul indication may be considered in the following situations: when AMF 9-03 reselects the TNL association due to the high latency of the selected backhaul network; when UPF selection is performed in SMF 9-05; when SMF 9-05 and RAN 9-02 allocate N3 tunnel information (CN tunnel information, AN tunnel information) for user plane data service transmission; or when SMF 9-05 and / or PCF 9-04 determine the Access Network Packet Delay Budget (ANPDB) (which is the maximum allowable latency between AN and UPF). The initial UE message may include the registration request message received from UE 9-01 in step 9-12. Upon receiving the initial UE message from RAN 9-02, AMF 9-03 can determine whether to use or change the TNL association used when the message was sent. If the decision is to change, in step 9-16a, AMF 9-03 can send a Next Generation Application Protocol (NGAP) UE-TNLA-binding modification message to RAN 9-02 via the newly selected TNL association, and RAN 9-02 can modify the NGAP UE-TNLA-binding with UE 9-01. If AMF 9-03 determines that there exists another AMF in its AMF set that has a TNL association with RAN 9-02, and that AMF has a more suitable TNL association, then AMF 9-03 can send a rerouting NAS request message to RAN 9-02 in step 9-16b. RAN 9-02 can identify the AMF set ID included in the rerouting NAS request message and perform the operation of selecting another AMF. Here, if another AMF is selected, RAN 9-02 can again execute steps 9-14 and 9-15. In addition, Figure 9 The document does not specifically mention the case of receiving a simple response message. In other words, when RAN 9-02 receives a response message from the selected AMF via the selected TNLA, step 9-17 can be executed.

[0092] In steps 9-17, the 3GPP 5G system can perform the remaining registration process.

[0093] Figure 10 This is a diagram illustrating a PDU session establishment process that takes into account the characteristics of a backhaul network according to an embodiment of the present disclosure.

[0094] In steps 10-11, UE 10-01 can send a PDU session establishment request message to RAN 10-02.

[0095] In steps 10-12, RAN 10-02 can determine the type of backhaul network traversed by the TNL association selected during registration by referring to the NGAP UE-TNLA binding associated with UE 10-01 that made the request in step 10-1. RAN 10-02 can determine whether QoS restriction may occur in the user plane based on the type and characteristics of the backhaul network used in the control plane, and can determine whether to notify AMF 10-03 of it. In the cases of (a) to (e) below, RAN 10-02 can determine to deliver a QoS-restricted backhaul indication to AMF 10-03.

[0096] (a) Where the selected backhaul network is a satellite backhaul network

[0097] (b) Where the selected backhaul network is a satellite backhaul network and there are no other candidate backhaul networks.

[0098] (c) Where the selected backhaul network is a satellite backhaul network and a satellite backhaul network exists among the other candidate backhaul networks.

[0099] (d) Where the selected backhaul network is a terrestrial backhaul network and the RAN can provide GTP-U channels via a satellite backhaul network.

[0100] (e) Where the selected backhaul network is a satellite backhaul network and the RAN is able to provide GTP-U channels via the satellite backhaul network.

[0101] Additionally, under the following (f) to (g) conditions, RAN 10-02 may determine not to transmit a QoS-restricted backhaul indication to AMF 10-03.

[0102] (f) When the selected backhaul network is a ground backhaul network and there are no other candidate backhaul networks.

[0103] (g) When the selected backhaul network is a ground-based backhaul network and the other candidate backhaul network is also a ground-based backhaul network.

[0104] In this case, QoS-restricted backhaul indications can be provided in the following forms (h) to (l).

[0105] (h) Whether QoS limiting can occur in the user plane

[0106] (i) Whether the satellite can be used for backhaul networks via the NG interface.

[0107] (j) The type of backhaul network used in the control plane (e.g., terrestrial, satellite, GEO satellite, MEO satellite, LEO satellite).

[0108] (k) Types of backhaul networks that can be used in the user plane

[0109] (l) Are different types of backhaul networks allowed in the control plane and user plane?

[0110] (m) A combination of all or some of the above (h) to (l).

[0111] In steps 10-13, AMF 10-03 can determine the type of backhaul network traversed by the TNL association selected during registration. AMF 10-03 can refer to the QoS-restricted backhaul indication received in step 10-12 or the NGAP UE-TNLA binding associated with UE 10-01 that made the request in step 10-11. If AMF 10-03 can immediately determine whether there is a possibility of QoS restriction occurring in the user plane via the QoS-restricted backhaul indication received in step 10-12 (e.g., (h) or (k)), step 10-14 described below can be omitted.

[0112] In steps 10-14, AMF 10-03 can determine whether different types of backhaul networks can be used in the control plane and user plane, and based on this, determine whether QoS restrictions will occur in the user plane. When AMF 10-03 determines that QoS restrictions will occur in the user plane, it may include the following (n) and (o).

[0113] (n) When it is determined in steps 10-13 that a terrestrial backhaul network is used in the control plane, and when it is known from the QoS-restricted backhaul indication received in steps 10-12 that other types of backhaul networks can be used in the user plane (e.g., case (d)).

[0114] (o) When it is determined in steps 10-13 that a satellite backhaul network is used in the control plane, and when it is known from the QoS-restricted backhaul indication received in steps 10-12 that other types of backhaul networks can be used in the user plane (e.g., the case of (l)).

[0115] In steps 10-15, based on the results determined in steps 10-13 and 10-14, AMF 10-03 can notify SMF 10-05 that QoS restrictions (QoS-restricted backhaul indication) will occur in the user plane. Based on the results determined in step 10-14, AMF 10-03 can notify SMF 10-05 that different types of backhaul networks can be used in the control plane and user plane (CP-UP backhaul separation indication).

[0116] In steps 10-16, SMF 10-05 and PCF 10-06 can perform the SM policy association establishment process. SMF 10-05 can deliver the QoS-restricted backhaul indication and CP-UP backhaul separation indication received from AMF 10-03 in step 10-15 to PCF 10-06 and assist PCF 10-06 in determining the PCC rules. When determining the AN PDB, SMF 10-05 or PCF 10-06 can refer to the QoS-restricted backhaul indication and CP-UP backhaul separation indication.

[0117] In steps 10-17, SMF 10-05 performs the UPF selection procedure. SMF 10-05 may refer to the QoS-restricted backhaul indication and CP-UP backhaul separation indication received from AMF 10-03 in step 10-15.

[0118] In steps 10-18, SMF 10-05 and UPF 10-04 can allocate CN tunnel information or network instances for user plane data service transmission. In this case, the QoS-restricted backhaul indication and CP-UP backhaul separation indication received from AMF 10-03 in step 10-15 can be referenced. SMF 10-05 or UPF 10-04 can determine the allocation of IP addresses, port numbers, etc., within a specific range for each type of backhaul network.

[0119] In steps 10-19, SMF 10-05 can deliver the CN tunnel information or network instance allocated in step 10-18 to AMF 10-03.

[0120] In steps 10-20, AMF 10-03 can deliver the information received in step 10-19 to RAN 10-02.

[0121] In steps 10-21, RAN 10-02 can establish user plane connections based on the information received in step 10-20. When performing AN tunnel information allocation, RAN 10-02 can refer to the results of determining in step 10-12 that QoS restrictions will occur in the user plane. RAN 10-02 can determine the allocation of IP addresses, port numbers, etc., within a specific range for each type of backhaul network.

[0122] In step 10-22, RAN 10-02 can transmit the AN tunnel information allocated in step 10-21 to AMF.

[0123] In steps 10-23, the 3GPP 5G system can perform the remaining PDU session establishment process.

[0124] Figure 11This is a diagram illustrating the structure of a UE according to an embodiment of the present disclosure.

[0125] Reference Figure 11 The UE may include a transceiver 1110, a controller 1120, and a storage device 1130. In this disclosure, the controller 1120 may be defined as a circuit or an application-specific integrated circuit or at least one processor.

[0126] Transceiver 1110 can send / receive signals to / from another network entity. Transceiver 1110 can, for example, receive system information from a base station, and can receive synchronization signals or reference signals. Transceiver 1110 can also send and receive the aforementioned messages.

[0127] The controller 1120 can control the overall operation of the UE according to the embodiments presented in this disclosure. For example, the controller 1120 can control the signal flow between blocks to execute the UE operations in the above signal flow diagram. Specifically, the controller 1120 can control the operations presented in this disclosure to manage sessions in a wireless communication system by taking backhaul information into account, according to the embodiments of this disclosure.

[0128] Storage device 1130 can store at least one of information sent and received by transceiver 1110 and information generated by controller 1120.

[0129] Figure 12 This is a diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0130] refer to Figure 12 The base station may include a transceiver 1210, a controller 1220, and a storage device 1230. In this disclosure, the controller 1220 may be defined as a circuit or an application-specific integrated circuit or at least one processor.

[0131] Transceiver 1210 can send / receive signals to / from another network entity. Transceiver 1210 can, for example, send system information to the UE, and can send synchronization signals or reference signals. Additionally, transceiver 1210 can send or receive messages to or from a specific entity in the network according to each of the above methods. Furthermore, transceiver 1210 can send the aforementioned signals / messages to and receive the aforementioned signals / messages from the UE.

[0132] Controller 1220 can control the overall operation of the base station according to the embodiments presented in this disclosure. For example, controller 1220 can control the signal flow between blocks to perform the operations of the base station (e.g., RAN or AN) in the above signal flow diagram. Specifically, controller 1220 can control the operations presented in this disclosure to manage sessions in a wireless communication system taking backhaul information into account, according to the embodiments of this disclosure.

[0133] Storage device 1230 can store at least one of information sent and received by transceiver 1210 and information generated by controller 1220.

[0134] Figure 13 This is a diagram illustrating the structure of a network entity according to an embodiment of the present disclosure.

[0135] Reference Figure 13 The network entity may include transceiver 1310, controller 1320, and storage device 1330. In this disclosure, controller 1320 may be defined as a circuit or application-specific integrated circuit or at least one processor.

[0136] Transceiver 1310 can transmit / receive signals to / from another network entity or base station. Transceiver 1310 can provide an interface for communicating with each network entity.

[0137] Controller 1320 can control the overall operation of network entities according to the embodiments presented in this disclosure. For example, in the above signal flow diagram, controller 1320 can control the signal flow between blocks to perform the operation of each network entity, such as the operation of the AMF when NF is an AMF or the operation of the SMF when NF is an SMF in the above signal flow. Specifically, controller 1320 can control the operations presented in this disclosure to manage sessions in a wireless communication system by taking backhaul information into account, according to the embodiments of this disclosure.

[0138] Storage device 1330 can store at least one of information sent and received by transceiver 1310 and information generated by controller 1320.

[0139] Industrial applicability

[0140] This disclosure can be applied to situations where backhaul networks are considered when establishing sessions between the RAN and AMF and / or UPF in a wireless communication system.

Claims

1. A session management method performed by an access network (AN) node of a wireless communication system using backhaul information, the method comprising: When a registration request message is received from a user equipment (UE), the access and mobility management function (AMF) is selected. Based on the type of backhaul network of the control plane associated with the Transport Network Layer Association (TNLA), a TNLA is selected from the candidate Transport Network Layer Associations (TNLAs) for the selected AMF; The initial UE message is sent to the selected AMF based on the selected TNLA; as well as Upon receiving the selected TNLA response signal from the selected AMF, the UE registration process is performed. The return network is of at least one of Low Earth Orbit (LEO) and Geosynchronous Earth Orbit (GEO).

2. The method according to claim 1, further comprising: Before receiving a registration request message, an information is established to provide connectable AMFs on the network with information about the radio interface with the UE located within radio coverage.

3. The method according to claim 2, wherein, The establishment also includes: Send to the AMF at least one of the following information: global RAN node ID, supported tracking areas (TAs), broadcast PLMN list, and radio access technology (RAT).

4. The method according to claim 1, further comprising: Modify the NGAP UE-TNLA-binding based on the UE-TNLA-binding modification message received from the selected AMF via the new TNLA; as well as The UE registration process is performed based on the modified NGAP-UE-TNLA-binding.

5. The method according to claim 1, further comprising: After sending the initial UE message to the selected AMF based on the selected TNLA, a rerouting NAS request message including the AMF set ID is received from the selected AMF, wherein the AMF set ID includes at least two different AMFs; Select the second AMF for session establishment from the AMFs included in the AMF set ID; To select the second AMF, a second TNLA is chosen from the candidate TNLAs; The initial UE message is sent to the selected second AMF based on the selected second TNLA; as well as Upon receiving the selected second TNLA response signal from the selected second AMF, the UE registration process is performed.

6. The method according to claim 1, wherein, Select a TNLA from the candidate TNLAs based on Quality of Service (QoS) constraints.

7. The method according to claim 1, wherein, Select a TNLA from the candidate TNLAs based on at least one of availability, weighting factor, or backhaul network type.

8. The method according to claim 7, wherein, The backhaul network type also includes ground backhaul networks.

9. An access network (AN) node device for managing sessions using backhaul information in a wireless communication system, the device comprising: The transceiver is configured to communicate with the user equipment (UE); The memory is configured to store session-related information. as well as At least one processor is configured as follows: When a registration request message is received from the UE via the transceiver, the Access and Mobility Management Function (AMF) is selected. Based on the type of backhaul network of the control plane associated with the Transport Network Layer Association (TNLA), a TNLA is selected from the candidate Transport Network Layer Associations (TNLAs) for the selected AMF. The transceiver sends the initial UE message to the selected AMF based on the selected TNLA, and Upon receiving the selected TNLA response signal from the selected AMF, the UE registration process is performed. The return network is of at least one of Low Earth Orbit (LEO) and Geosynchronous Earth Orbit (GEO).

10. The device according to claim 9, wherein, The at least one processor is configured to: Before receiving a registration request message, an information is established to provide connectable AMFs on the network with information about the radio interface with the UE located within radio coverage.

11. The device according to claim 10, wherein, The at least one processor is configured to: During setup, at least one of the following information is sent to the AMF via a transceiver: global RAN node ID, supported tracking area (TA) broadcasts, broadcast PLMN list, and radio access technology (RAT).

12. The device according to claim 9, wherein, The at least one processor is configured to: Modify the NGAP UE-TNLA-binding based on the UE-TNLA-binding modification message received from the selected AMF via the new TNLA; as well as The UE registration process is performed based on the modified NGAP UE-TNLA binding.

13. The device according to claim 9, wherein, The at least one processor is configured to: After sending the initial UE message to the selected AMF via a transceiver based on the selected TNLA, a rerouting NAS request message including the AMF set ID is received from the selected AMF, wherein the AMF set ID includes at least two different AMFs; Select the second AMF for session establishment from the AMFs included in the AMF set ID; To select the second AMF, a second TNLA is chosen from the candidate TNLAs; Based on the selected second TNLA, the initial UE message is sent to the selected second AMF via the transceiver; as well as Upon receiving the selected second TNLA response signal from the selected second AMF, the UE registration process is performed.

14. The device according to claim 9, wherein, The at least one processor is configured to: Based on Quality of Service (QoS) constraints, select one TNLA from the candidate TNLAs.

15. The device according to claim 9, wherein, The at least one processor is configured to: A TNLA is selected from candidate TNLAs based on at least one of availability, weighting factor, or backhaul network type. The backhaul network type also includes ground backhaul networks.

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