Wireless access network node, wireless terminal and method thereof

Abstract

The present application relates to a wireless access network node, a wireless terminal and a method thereof. A target RAN node associated with a second network includes: at least one memory; and at least one processor connected to the memory, the processor being configured to: receive a handover request message from a source RAN node in a first network on a direct interface, the handover request message requesting a handover of the wireless terminal from the first network to the second network; upon receiving the handover request message, create wireless resource configuration information to be used by the wireless terminal in the second network after the handover; and send the wireless resource configuration information to the wireless terminal via the source RAN node, wherein the handover request message contains slice information and flow information, the slice information is related to at least one network slice allocated to the core network to which the wireless terminal is connected, and the flow information is related to at least one packet flow of a PDU session established in the core network.

Description

[0001] This application is a divisional application of the invention patent application with application date of May 15, 2017, application number 201780048078.2, and titled "Wireless access network node, wireless terminal, core network node and method thereof". Technical Field

[0002] The present invention relates to a wireless communication system, and in particular, to a handover of a wireless terminal between different radio access technologies (RATs). Background Art

[0003] The 3rd Generation Partnership Project (3GPP) began working on the standardization of the fifth generation mobile communication system (5G) in 2016 (i.e., 3GPP Release 14) to make 5G a commercial reality in 2020 (see Non-Patent Literature 1). 5G is expected to be achieved through the continued enhancement / evolution of LTE and Advanced LTE and through the introduction of innovative enhancement / evolution of new 5G air interfaces (i.e., new radio access technologies (RATs)). The new RAT supports, for example, higher frequency bands than those supported by LTE / Advanced LTE and its continued evolution (e.g., below 6 GHz). For example, the new RAT supports centimeter wave bands (above 10 GHz) and millimeter wave bands (above 30 GHz).

[0004] In this specification, the fifth generation mobile communication system is also referred to as the next generation (NextGen) system (NG system). The new RAT of the NG system is called new radio (NR), 5G RAT or NG RAT. The new radio access network (RAN) and core network of the NG system are respectively referred to as NextGen RAN (NG RAN) and NextGen core (NG core). The wireless terminal (ie, user equipment (UE)) connected to the NG system is called NextGen UE (NG UE). As standardization work progresses, the official names of RAT, UE, radio access network, core network, network entity (or node), protocol layer, etc. of the NG system will be determined in the future.

[0005] Unless otherwise specified, the term "LTE" used in this specification includes enhancements / evolutions of LTE and Advanced LTE to provide interworking with NG systems. The enhancements / evolutions of LTE and Advanced LTE used for interworking with NG systems are also referred to as Advanced LTE Pro, LTE+, or enhanced LTE (eLTE). In addition, unless otherwise specified, the terms related to LTE networks and logical entities used in this specification (such as "Evolved Packet Core (EPC)", "Mobility Management Entity (MME)", "Serving Gateway (S-GW)", and "Packet Data Network (PDN) Gateway (P-GW)", etc.) include their enhancements / evolutions to provide interworking with NG systems. Enhanced EPC, enhanced MME, enhanced S-GW, and enhanced P-GW are also referred to as, for example, enhanced EPC (eEPC), enhanced MME (eMME), enhanced S-GW (eS-GW), and enhanced P-GW (eP-GW), respectively.

[0006] In LTE and LTE-Advanced, in order to achieve quality of service (QoS) and packet routing, bearers for each QoS level and for each PDN connection are used in both the RAN (i.e., Evolved Universal Terrestrial RAN) and the core network (i.e., Evolved Packet Core (EPC)). That is, in the bearer-based QoS (or QoS for each bearer) concept, one or more Evolved Packet System (EPS) bearers are configured between the UE and the P-GW in the EPC, and multiple service data flows (SDFs) with the same QoS level are transmitted via one EPS bearer that meets the QoS. SDF is one or more packet flows that match the SDF template (i.e., packet filter) based on the policy and charging control (PCC) rules. In addition, each packet to be sent via the EPS bearer used for packet routing contains information for identifying which bearer (i.e., General Packet Radio Service (GPRS) Tunneling Protocol (GTP) tunnel) the packet is associated with.

[0007] In contrast, with respect to the NG system, it has been suggested that although radio bearers can be used in the NG RAN, bearers are not used in the NG core or in the interface between the NG RAN and the NG core (see non-patent document 1). Specifically, a PDU flow is defined instead of the EPS bearer, and one or more SDFs are mapped to one or more PDU flows. The PDU flow between the NG UE and the user plane terminal entity in the NG core (i.e., the entity corresponding to the P-GW in the EPC) corresponds to the EPS bearer in the EPS bearer-based QoS concept. That is, instead of the bearer-based QoS concept, the NG system adopts the flow-based QoS (or QoS for each flow) concept. In the flow-based QoS concept, QoS is handled for each PDU flow. Note that the association between the UE and the data network is called a "PDU session". The term "PDU session" corresponds to the term "PDN connection" in LTE and Advanced LTE. Multiple PDU flows can be configured in one PDU session.

[0008] In this specification, a system (such as LTE and Advanced LTE systems, etc.) for configuring an end-to-end bearer (e.g., EPS bearer) between a UE and an edge node (e.g., P-GW) in a core network and adopting a bearer-based QoS concept is referred to as a "bearer-based system" or a "bearer-based network". In contrast, a system (such as an NG system, etc.) for not using any bearer in the core network or in the interface between the core network and the RAN and adopting a flow-based QoS concept is referred to as a "bearerless system" or a "bearerless network". Similar to the above-mentioned NG system, a wireless bearer can be used in the RAN of the bearerless network. The term "bearerless" can also be expressed as, for example, no GTP, no (PDN) connection, no tunnel, (IP) flow-based, SDF-based, streaming media-based, or (PDU) session-based. However, in this specification, the NG system can be used as a bearer-based system and can support both flow-based transmission of user data and bearer-based transmission of user data.

[0009] In addition, it has been suggested that NG systems support network slicing (see non-patent document 1). Network slicing uses network function virtualization (NFV) technology and software defined network (SDN) technology, and makes it possible to create multiple virtualized logical networks on a physical network. Each virtualized logical network is called a network slice or a network slice instance, includes logical nodes and functions, and is used for specific traffic and signaling. The NG RAN or the NG core or both have a slice selection function (SSF). The SSF selects one or more network slices suitable for the NGUE based on information provided by at least one of the NG UE and the NG core.

[0010] Patent document 1 discloses switching from a bearerless network (e.g., 5G) to a bearer-based network (e.g., LTE) and switching from a bearer-based network (e.g., LTE) to a bearerless network (e.g., 5G). In the switching from 5G to LTE disclosed in patent document 1, the source control node (i.e., access control server (ACS) / eMME) in the 5G core (or NG core) maps the QoS parameters of the service flow in the bearerless network (i.e., 5G) to the EPS bearer-level QoS in the bearer-based network (i.e., LTE). The QoS parameters of the service flow of 5G are, for example, DiffServ (Differentiated Services) Code Point (DSCP) values. The EPS bearer-level QoS in LTE is, for example, QoS Class Identifier (QCI) and Allocation and Retention Priority (ARP). The mapping of DSCP values ​​to EPS bearers can be performed in a one-to-one manner or in an n-to-one manner. The source ACS / eMME sends the APN information including information related to the EPS bearer-level QoS to the target MME. The target MME sets the GTP tunnel used by the UE based on the received APN information.

[0011] In addition, in the handover from LTE to 5G disclosed in Patent Document 1, the source MME in the LTE core (i.e., EPC) sends a forward relocation request containing the required bearer context information to the target ACS / eMME in the 5G core (NG core). The target ACS / eMME maps the QCI value received from LTE (i.e., the source MME) to the 5G QoS parameters (i.e., DSCP values) and supplies them to the transmission node (i.e., mobile gateway access router (M-GW / AR) or mobile gateway edge router (M-GW / ER)) in the 5G core (or NG core). By doing so, the target ACS / eMME sets up at least one generic routing encapsulation (GRE) tunnel for transmitting the UE's service flow (i.e., IP packets).

[0012] Prior art literature

[0013] Patent Literature

[0014] Patent Document 1: International Publication No. 2015 / 160329

[0015] Non-patent literature

[0016] Non-patent document 1: 3GPP TR 23.799 V0.6.0 (2016-07) “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Study on Architecture for Next Generation System (Release 14)”, July 2016 Summary of the invention

[0017] Problem that the invention aims to solve

[0018] The inventors have studied the handover between the NG system (ie, 5G) and the LTE system and found several problems. Figure 4 The handover process from the NG system (5G) to the LTE system is shown to be implemented by modifying the handover based on LTE S1. However, Patent Document 1 does not disclose that the handover process from the NG system (5G) to the LTE system includes transmitting a handover signaling message on a direct base station interface.

[0019] Therefore, one of the purposes to be achieved by the embodiments disclosed herein is to provide the following apparatus, method and program, wherein the apparatus, method and program are helpful to provide an inter-RAT handover process involving the transmission of handover signaling messages on a direct inter-base station interface. It should be noted that the above purpose is only one of the purposes to be achieved by the embodiments disclosed herein. Other purposes or problems and novel features will become apparent through the following description and drawings.

[0020] Solutions for solving problems

[0021] In one aspect, a target radio access network node, i.e., a target RAN node, is associated with a second network, the target RAN node comprising: at least one memory; and at least one processor connected to the at least one memory. The at least one processor is configured to: receive a handover request message from a source RAN node in a first network on a direct interface, the handover request message requesting a handover of a wireless terminal from the first network to the second network; in response to receiving the handover request message, receive at least one of slice information and flow information from a core network; and control communication of the wireless terminal based on at least one of the slice information and the flow information, wherein the slice information is related to a network slice in the second network to which the wireless terminal is to be connected, and the flow information is related to at least one session to be established in the second network used as an unloaded network in order to transmit at least one packet flow of the wireless terminal.

[0022] In one aspect, a source radio access network node, ie, a source RAN node, is associated with a first network, the source RAN node comprising: at least one memory; and at least one processor connected to the at least one memory. The at least one processor is configured to: determine a handover of the wireless terminal from the first network to the second network; in response to the determination of the handover, send a handover request message to a target RAN node in the second network on a direct interface, the handover request message requesting the handover of the wireless terminal to the second network; receive a handover request confirmation message containing a transparent container from the target RAN node on the direct interface; and send a mobility command message containing the transparent container and indicating a handover to the second network to the wireless terminal, wherein the transparent container includes wireless resource configuration information required by the wireless terminal to establish a wireless connection associated with the second network, and the wireless resource configuration information includes at least one of the following: (a) first wireless resource configuration information generated based on slice information, the slice information being related to a network slice in the second network to which the wireless terminal is to be connected; and (b) second wireless resource configuration information generated based on flow information, the flow information being related to at least one session to be established in the second network used as an unloaded network in order to transmit at least one packet flow of the wireless terminal.

[0023] In one aspect, a wireless terminal comprises: at least one memory; and at least one processor connected to the at least one memory. The at least one processor is configured to receive a handover-related message from a radio access network node (RAN node) of a first network to which the wireless terminal is connected during a handover from the first network to a second network, the handover-related message comprising at least one of the following: slice information related to a network slice in the second network; and radio resource configuration information based on the network slice in the second network.

[0024] In one aspect, a core network node comprises: at least one memory; and at least one processor connected to the at least one memory. The at least one processor is configured to send slice information related to a network slice included in the second network to which the wireless terminal is to connect to to a target radio access network node (i.e., a target RAN node) associated with the second network during a handover of a wireless terminal from a first network to a second network.

[0025] In one aspect, a method in a target radio access network node, i.e., a target RAN node, the target RAN node being associated with a second network, the method comprising:

[0026] receiving a handover request message from a source RAN node in a first network over a direct interface, the handover request message requesting handover of a wireless terminal from the first network to the second network;

[0027] In response to receiving the handover request message, receiving at least one of slice information and flow information from a core network; and

[0028] The communication of the wireless terminal is controlled based on at least one of the slice information and the flow information. The slice information is related to a network slice in the second network to which the wireless terminal is to be connected, and the flow information is related to at least one session to be established in the second network serving as an unbearable network for transmitting at least one packet flow of the wireless terminal.

[0029] In one aspect, a method in a source radio access network node, i.e., a source RAN node, the source RAN node being associated with a first network, the method comprising:

[0030] Determining a handover of the wireless terminal from the first network to the second network;

[0031] In response to the determination of the handover, sending a handover request message to a target RAN node in the second network on a direct interface, the handover request message requesting handover of the wireless terminal to the second network;

[0032] receiving a handover request confirmation message including a transparent container from the target RAN node over the direct interface; and

[0033] A mobility command message including the transparent container and indicating a handover to the second network is sent to the wireless terminal. The transparent container includes wireless resource configuration information required by the wireless terminal to establish a wireless connection associated with the second network, and the wireless resource configuration information includes at least one of the following: (a) first wireless resource configuration information generated based on slice information, the slice information being related to a network slice in the second network to which the wireless terminal is to be connected; and (b) second wireless resource configuration information generated based on flow information, the flow information being related to at least one session to be established in the second network serving as a bearerless network in order to transmit at least one packet flow of the wireless terminal.

[0034] In one aspect, a program comprises a set of instructions (software codes), wherein the set of instructions (software codes) when loaded into a computer causes the computer to perform the method according to the above aspect.

[0035] Effects of the Invention

[0036] According to the above aspects, a device, method and program may be provided, wherein the device, method and program facilitate providing an inter-RAT handover procedure involving transmission of a handover signaling message over a direct inter-base station interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Shown is an example of the structure of a wireless communication network according to some embodiments.

[0038] Figure 2A is a sequence diagram showing an example of an Inter-RAT handover procedure from an LTE system to an NG system according to the first embodiment.

[0039] Figure 2B is a sequence diagram showing an example of an Inter-RAT handover procedure from an LTE system to an NG system according to the first embodiment.

[0040] Figure 3A is a sequence diagram showing an example of an Inter-RAT handover procedure from an LTE system to an NG system according to the first embodiment.

[0041] Figure 3B is a sequence diagram showing an example of an Inter-RAT handover procedure from an LTE system to an NG system according to the first embodiment.

[0042] Figure 4 is a flowchart showing an example of a method performed by a target NR Node B (NR NB) according to the first embodiment.

[0043] Figure 5 is a flow chart showing an example of a method performed by a source LTE eNB according to the first embodiment.

[0044] Figure 6 is a flow chart showing an example of a method performed by a core network according to the first embodiment.

[0045] Figure 7 is a flowchart showing an example of a method performed by the wireless terminal according to the first embodiment.

[0046] Figure 8 is a sequence diagram showing an example of an Inter-RAT handover procedure from an LTE system to an NG system according to the second embodiment.

[0047] Fig. 9A is a sequence diagram showing an example of an Inter-RAT handover procedure from an LTE system to an NG system according to the second embodiment.

[0048] Fig. 9B is a sequence diagram showing an example of an Inter-RAT handover procedure from an LTE system to an NG system according to the second embodiment.

[0049] Fig. 10A is a sequence diagram showing an example of an Inter-RAT handover procedure from an NG system to an LTE system according to the third embodiment.

[0050] Fig. 10B is a sequence diagram showing an example of an Inter-RAT handover procedure from an NG system to an LTE system according to the third embodiment.

[0051] Fig.11A is a sequence diagram showing an example of an Inter-RAT handover procedure from an NG system to an LTE system according to the third embodiment.

[0052] Fig. 11B is a sequence diagram showing an example of an Inter-RAT handover procedure from an NG system to an LTE system according to the third embodiment.

[0053] Fig.12 2 is a diagram showing a configuration example of a wireless communication network according to the fourth embodiment.

[0054] Fig.13 is a sequence diagram showing an example of intra-NR switching processing according to the fourth embodiment.

[0055] Fig.14 : is a sequence diagram showing an example of an intra-NR switching process according to the fourth embodiment.

[0056] Fig.15 is a sequence diagram showing an example of intra-NR switching processing according to the fourth embodiment.

[0057] Fig.16 is a sequence diagram showing an example of intra-NR switching processing according to the fourth embodiment.

[0058] Fig.17 is a sequence diagram showing an example of intra-NR switching processing according to the fourth embodiment.

[0059] Fig.18 is a sequence diagram showing an example of intra-NR switching processing according to the fourth embodiment.

[0060] Fig.19 is a block diagram showing an example of the structure of a wireless terminal according to some embodiments.

[0061] Fig. 20 is a block diagram showing a structural example of a base station according to some embodiments.

[0062] Fig.21 is a block diagram showing a structural example of a base station according to some embodiments.

[0063] Fig. 22 is a block diagram illustrating a structural example of a core network node according to some embodiments.

[0064] Fig.23A An example of the format of a Mobility from EUTRA command message is shown.

[0065] Fig. 23B An example of the format of a Mobility Command message from EUTRA is shown.

[0066] Fig.24 An example of the format of the NR Handover Request message is shown.

[0067] Fig.25 An example of the format of UE context information is shown.

[0068] Fig.26 An example of the format of the NR Handover Request Confirm message is shown.

[0069] Fig. 27 An example of the format of the NR Handover Request Confirm message is shown.

[0070] Fig.28 An example showing the format of the NG Core Context.

[0071] Fig.29 An example of the format of slice information is shown.

[0072] Fig.30 An example of the format of stream information is shown.

[0073] Fig.31 An example of the format of a session endpoint ID is shown. Specific embodiments

[0074] The specific embodiments are described in detail below with reference to the accompanying drawings. In the entire drawings, the same reference numerals are used to represent the same or corresponding elements, and for the sake of clarity, repeated descriptions will be omitted as needed.

[0075] Each embodiment described below can be used alone, or two or more of these embodiments can be appropriately combined with each other. These embodiments include novel features that are different from each other. Therefore, these embodiments help to achieve different purposes or solve different problems from each other, and also help to obtain different advantages from each other.

[0076] First embodiment

[0077] Figure 1 An example of a structure of a wireless communication network according to some embodiments including this embodiment is shown. Figure 1In the example shown, the wireless communication network includes a wireless terminal (UE) 1, an LTE base station (i.e., eNB) 2, a new radio (NR) base station (i.e., NR Node B (NR NB)) 3, and a NextGen (NG) core 5. The LTE eNB 2 is connected to the NG core 5. Specifically, the LTE eNB 2 is connected to the MME in the NG core 5 via a control plane interface (e.g., NG2 interface), or to a control node (i.e., control plane function (CPF) node) arranged in the NG core 5 and having at least part of the functions of the MME. The LTE eNB 2 is also connected to the service gateway (S-GW) in the NG core 5 via a user plane interface (e.g., NG3 interface), or to a data node (i.e., user plane function (UPF) node) arranged in the NG core 5 and having at least part of the functions of the S-GW. The LTE eNB 2 enhanced to be connected to the NG core 5 may be referred to as an eLTE eNB.

[0078] Likewise, the NR NB 3 may be connected to one or more CPF nodes in the NG core 5 via a control plane interface (e.g., NG2 interface). In addition, the NR NB 3 may be connected to one or more UPF nodes in the NG core 5 via a user plane interface (e.g., NG3 interface). In addition, the UE 1 may be connected to one or more CPF nodes in the NG core 5 via a control plane interface (e.g., NG1 interface). The NG1 interface may be defined as a logical interface for transmitting NAS layer information, and the transmission of the NAS layer information may be performed via the NG2 interface as well as via a wireless interface (e.g., NG Uu) between the NR NB 3 and the UE 1.

[0079] In some implementations, the NG core 5 may be provided with a virtualized network slice that provides a logical EPC node and EPC functions. In some implementations, the E-UTRAN including the LTE eNB 2 may be connected to the same network slice as the NG RAN including the NR NB 3. Alternatively, the E-UTRAN including the LTE eNB 2 and the NG RAN including the NR NB 3 may be connected to different network slices from each other. The UE1 has the ability to connect to the LTE system provided by the LTE eNB 2 and the NG core 5, and also has the ability to connect to the NextGen (NG) system provided by the NR NB 3 and the NG core 5.

[0080] The LTE eNB 2 is connected to the NR NB 3 via a direct base station interface 101. The direct base station interface 101 is called, for example, an X3 interface. The direct base station interface 101 is at least used to transmit signaling messages between the LTE eNB 2 and the NR NB 3. The direct base station interface 101 may also be used to transmit user packets between the LTE eNB 2 and the NR NB 3. The control plane protocol structure and the user plane protocol structure of the direct base station interface 101 may be, for example, the same as the control plane protocol structure and the user plane protocol structure of the X2 interface between the LTE eNBs.

[0081] In addition to the above-mentioned NG1 interface, NG2 interface and NG3 interface, the NG system may also include other interfaces. Each interface may be referred to as a reference point. NG RAN (i.e., different NR NBs) may be connected to each other via the NX2 interface. A CPF node having either or both of a mobility management function (MMF) and a session management function (SMF) may be connected to a UPF node via a control plane interface (e.g., NG4 interface). Different UPF nodes may be connected to each other via a user plane interface (e.g., NG9 interface). CPF nodes with different functions may be connected to each other via a control plane interface. For example, a CPF node having MMF and SMF may be connected to a CPF node having a policy control function (PCF) via a control plane interface (e.g., NG7 interface). A CPF node having MMF and SMF may be connected to a node having a user data management (SDM) function via a control plane interface (e.g., NG8 interface). A CPF node may be connected to a node having an application function (AF) via a control plane interface (e.g., NG5 interface). The UPF node can be connected to an external or local data network (DN) via a user plane interface (e.g., NG6 interface). The SMF may include functions for authenticating users or terminals and authorizing services or network slices. The above network nodes are individually or collectively referred to as network functions (NFs).

[0082] In some implementations, the NG system including the NR NB 3 and the NG core 5 supports data transmission based on the above-mentioned flow-based QoS (or QoS for each flow) concept. The NG system including the NR NB 3 and the NG core 5 can also be configured to support bearer-based transmission using bearers for each QoS level and for each PDU session. The bearers in the NG system can be configured between a pair of network functions (NFs) (for example, between the NR NB 3 and the user plane function in the NG core 5, or between two user plane functions in the NG core 5). Optionally, the bearers in the NG system can be configured between the UE 1 and the user plane function in the NG core 5 via the NR NB 3. The bearers in the NG system may be referred to as NG-EPS bearers, and the radio access bearers in the NG system may be referred to as NG-RABs. The bearers in the NG system can be used to transmit multiple packet flows (i.e., PDU flows).

[0083] The NG-RAB may include a radio bearer configured between the UE 1 (NG UE) and the NR NB 3, and a bearer (e.g., an NG3 bearer) configured between the NR NB 3 and the user plane function in the NG core 5 (e.g., an edge gateway (edge ​​GW)). The NG-EPS bearer may include the NG-RAB, and a core network bearer (e.g., an NG9 bearer) configured between the user plane functions in the NG core 5 (e.g., between the edge GW and the data network gateway (DN GW)). The edge GW is a gateway to the radio access network and has similar user plane functions to the LTE S-GW. However, in the NG system, unlike the LTE S-GW, the UE 1 can be connected to multiple edge GWs. The DN GW is a gateway to the external network (i.e., the data network) and has similar user plane functions to the LTE P-GW. In the NG system, like the LTE P-GW, the UE 1 can be connected to multiple DN GWs.

[0084] More specifically, an NG-EPS bearer may be configured between UE 1 (i.e., NG UE) and a slice-specific user plane function (i.e., slice-specific user plane NF (SUNF)) in the NG core 5. An NG-RAB may be configured between UE 1 (i.e., NG UE) and a common user plane function (i.e., common user plane NF (CUNF)) in the NG core 5. In this case, CUNF provides the function of an edge GW, and SUNF provides the function of a DN GW. CUNF may associate the NG-RAB with a core network bearer (e.g., NG9 bearer). That is, the NG-EPS bearer may include the NG-RAB between UE 1 (i.e., NG UE) and CUNF and a core network bearer (e.g., NG9 bearer) between CUNF and SUNF.

[0085] The NG system supporting bearer-based transmission may also be configured to identify data flows (e.g., PDU flows) in the bearer to perform QoS processing (e.g., packet discard) on a per-data-flow basis (e.g., per-PDU-flow basis). For example, NR NB3 may associate a bearer (e.g., NG3 bearer) configured between NR NB 3 and a user plane function in the NG core 5 with a radio bearer, perform packet forwarding between the bearer (e.g., NG3 bearer) and the radio bearer, and perform QoS processing (e.g., packet discard) on each data flow (e.g., PDU flow) in the bearer.

[0086] Note that in the case where the (e)LTE eNB 2 is connected to the NG core 5 via the NG2 interface, the radio access bearer corresponding to the EPS radio access bearer (E-RAB) of LTE can be defined as an NG EPS radio access bearer (NE-RAB), and the bearer corresponding to the EPS bearer of LTE can be defined as an NG EPS bearer (NEPS bearer). The NE-RAB may include a radio bearer configured between the UE 1 and the LTE eNB 2, and a bearer configured between the LTE eNB 2 and a user plane function in the NG core 5 (e.g., an edge GW or a CUNF) (e.g., an NG3 bearer). The NEPS bearer may include the NE-RAB, and a core network bearer configured between user plane functions in the NG core 5 (e.g., between the edge GW and the DN GW, or between the CUNF and the SUNF) (e.g., an NG9 bearer).

[0087] The LTE eNB 2 connected to the NG system may be configured to identify data flows (e.g., PDU flows) in the NE-RAB to perform QoS processing (e.g., packet discarding) on ​​a per-data-flow basis (e.g., on a per-PDU-flow basis). For example, the LTE eNB 2 may associate a bearer (e.g., NG3 bearer) configured between the LTE eNB 2 and the user plane function in the NG core 5 with a radio bearer, perform packet forwarding between the bearer (e.g., NG3 bearer) and the radio bearer, and perform QoS processing (e.g., packet discarding) on ​​each data flow (e.g., PDU flow) in the bearer.

[0088] This embodiment provides a method for switching UE 1 from an LTE system that does not support network slicing to an NG system that supports network slicing. Figure 2A and 2B The method for transferring UE 1 from Figure 1 An example of a process of switching from an LTE system to an NG system in the structure example of a wireless communication network shown. Figure 2A shows the switching preparation phase and the switching execution phase, and Figure 2B The handover completion phase is shown.

[0089] Figure 2A and 2B The process shown is similar to "X2-based handover" in LTE in that it involves the transmission of handover signaling messages on the direct inter-base station interface 101 during the handover preparation phase (i.e., steps 202 and 203). However, if only the transmission of handover signaling messages on the direct inter-base station interface 101 is performed, there is insufficient information for the relocation of UE 1 from the LTE system to the NG system in the NG RAN. Figure 2A and 2B In the process shown, the handover completion phase is improved to include signaling between the NR NB 3 and the NG core 5 (i.e., steps 207, 209 and 210) to obtain the information required for the relocation of the UE 1 from the LTE system to the NG system.

[0090] In step 201, UE 1 is connected to LTE eNB 2 and is in a connected state (i.e., RRC_Connected). UE 1 receives measurement configuration from LTE eNB 2, performs neighbor cell measurement including measurement of E-UTRAN (LTE) cells and NG-RAN cells and inter-radio access technology (inter-RAT) measurement according to the received measurement configuration, and sends a measurement report to LTE eNB 2. The measurement configuration is included in an RRC connection reconfiguration message sent from E-UTRAN to UE, for example.

[0091] In step 202, LTE eNB 2 determines an inter-RAT handover to the cell of NR NB 3. When determining the inter-RAT handover, LTE eNB 2 sends an NR handover request message to the target NR NB 3 on the direct inter-base station interface 101 (e.g., X3 interface).

[0092] The NR handover request message in step 202 may include a handover type information element (IE) indicating a handover from LTE to NR. For example, the handover type IE is set to "LTE to NR".

[0093] The NR handover request message in step 202 may also include a "List of NG EPS Radio Access Bearers (NE-RABs) to be set up" information element (IE). The "List of NE-RABs to be set up" IE indicates the identifier (i.e., NE-RAB ID) and QoS parameters (e.g., QoS Class Identifier (QCI), Allocation and Reservation Priority (ARP), and Guaranteed Bit Rate (GBR) QoS information) of each NE-RAB used by UE 1. NextGen E-RAB (NE-RAB) is an E-RAB set up between UE 1 and a user plane function (e.g., Common User Plane NF (CUNF)) in NG Core 5 via an eLTE eNB enhanced to support an interface with the NG Core.

[0094] The NR handover request message in step 202 may also include a "Handover preparation information to NR" information element (IE). For example, the "Handover preparation information to NR" IE may include auxiliary information for facilitating the mapping between EPS bearers and packet flows (e.g., PDU flows or SDFs) used by UE 1. The auxiliary information may indicate an identifier or packet filter (e.g., an SDF template or TFT) of one or more SDFs mapped to each EPS bearer. The auxiliary information may be sent from UE 1 to LTE eNB 2 via an RRC message. In addition, the auxiliary information may be sent as an information element (IE) containing parameters of the RRC layer, or may be sent as an IE in the RRC layer containing information related to the NAS layer (e.g., NAS Info IE).

[0095] Additionally or optionally, the "handover preparation information to NR" IE may include security related information. The security related information includes security parameters to be used by the target NR NB 3 to derive the access layer (AS) security key. These security parameters include the basic key (i.e., the same as the K of LTE) used to derive the security key (or temporary key) used by the AS layer. eNB The security parameters may also include the UE security capabilities related to the NG RAT or NG system. The UE security capabilities indicate the encryption and integrity protection algorithms implemented in the UE 1.

[0096] For example, similar to the existing X2 handover process, the source LTE eNB 2 can derive K from the unused {NH, NCC} pair. eNB *, and {K eNB *, NCC} pair is sent to the target NR NB 3. The next hop parameter (NH) and the next hop chain counter parameter (NCC) are used to derive K according to the vertical key derivation algorithm used by the next hop.eNB Optionally, the source LTE eNB 2 may derive a key from the current K eNB Derivation of K eNB *, and {K eNB *,NCC} pair is sent to the target NR NB 3.

[0097] Optionally, the source LTE eNB 2 may send an unused {NH, NCC} pair to the target NR NB 3. In this case, the target NR NB 3 may derive a basic key (i.e., a key corresponding to the LTE K) from the received unused {NH, NCC} pair according to the key derivation algorithm in the vertical direction. eNB corresponding key) and AS key.

[0098] The NR handover request message in step 202 may also include auxiliary information used for network slicing (e.g., auxiliary data used for network slicing). The "Assistance Data Used for Network Slicing" IE contains network slicing assistance information used to facilitate network slicing. The network slicing assistance information may, for example, indicate the type of UE 1, the service desired by UE 1, the acceptable delay of UE 1, or any combination thereof. Optionally, part or all of the network slicing assistance information may be included in the handover preparation information (or another information element) of the RRC container (e.g., RRC context IE). The network slicing assistance information may be generated by the EPC network slicing instance in UE 1, LTE eNB 2, or NG core 5. For example, UE 1 may send the network slicing assistance information to LTE eNB 2 in step 201. The network slicing assistance information may be an information element (IE) indicating parameters of the RRC layer, or may be NAS information (e.g., NAS information IE), and may be included in a measurement report sent from UE 1 to LTE eNB 2.

[0099] In step 203, the target NR NB 3 generates a UE context and allocates resources based on the NR handover request message. The target NR NB 3 can determine the accepted E-RABs based on the received "List of E-RABs to be Set" IE. The target NR NB 3 can determine the stream identifiers (e.g., PDU stream IDs) corresponding to the accepted E-RABs, the endpoint information of the target NR NB 3 used for the delivery of the uplink (UL) PDU, and the endpoint information of the target NR NB 3 used for the delivery of the downlink (DL) PDU. The endpoint information of the target NR NB 3 used for the delivery of the UL PDU can be a UL GTP tunnel endpoint identifier (TEID), or can be one or both of the UL endpoint ID and the Internet Protocol (IP) address. Similarly, the endpoint information of the target NR NB 3 used for the delivery of the DL PDU can be a DL GTP TEID, or can be one or both of the DL endpoint ID and the IP address. The endpoint information used for the delivery of the UL PDU is used to forward UL data, while the endpoint information used for the delivery of the DL PDU is used to forward DL data.

[0100] In addition, in the case where the NR handover request message in step 203 includes security-related information, the target NR NB 3 may operate as follows. As described above, the security-related information includes security parameters of AS security. The target NR NB 3 may select an AS security algorithm based on the UE security capabilities included in the security parameters. The AS security algorithm includes an encryption algorithm for radio resource control (RRC) and user plane (UP), and also includes an integrity protection algorithm for RRC. In addition, the target NR NB 3 may select an AS security algorithm based on a basic key obtained from the security parameters (i.e., a key corresponding to the UE's K of LTE) by using the selected security algorithm. eNB The corresponding key) is used to derive the temporary key used for RRC encryption (ciphering (or encryption)), UP encryption and RRC integrity protection.

[0101] The target NR NB 3 generates a target-to-source transparent container (Source TransparentContainer) to be sent to UE 1. The target-to-source transparent container, for example, includes an RRC: Handover Command message (e.g., a handover command to NR) containing an RRC connection reconfiguration message and other RRC messages. Then, the target NR NB 3 generates a confirmation response (e.g., a handover request confirmation) message containing the target-to-source transparent container as a response to the handover request. The target NR NB 3 sends the NR handover request confirmation message to the source LTE eNB 2 on the direct base station interface 101 (e.g., X3 interface). The target-to-source transparent container, for example, includes the radio resource configuration information (e.g., radio parameters) set by the target NR NB 3, the identifier of the AS security algorithm selected by the target NR NB 3, and the NCC value. The NR handover request confirmation message may also include the above-mentioned "accepted NE-RAB list" information element (IE). The source LTE eNB 2 starts data forwarding for the bearer or flow (e.g., PDU flow) specified by the "accepted NE-RAB list" IE.

[0102] In step 204, the source LTE eNB 2 sends a radio resource control (RRC) message including a handover command message to the UE 1, and the handover command message includes a transparent container generated by the target NR NB 3. The RRC message may be, for example, a mobility command message from EUTRA or an RRC connection reconfiguration message.

[0103] In step 205, in response to receiving the RRC message containing the handover command message, UE 1 moves to the target RAN (i.e., NG RAN) and performs handover according to the transparent container (e.g., radio resource configuration information, AS security algorithm, and NCC value) provided by the handover command message. That is, UE 1 establishes a wireless connection with the target NR NB3 associated with the bearerless network (i.e., NG system). In step 206, after successfully synchronizing to the target cell, UE 1 sends a handover confirmation for the NR message to the target NR NB 3. The message in step 206 may be an NR RRC connection reconfiguration complete message.

[0104] In step 207, when UE 1 successfully accesses the target NR NB 3, the target NR NB 3 sends an NR path switch request message to the NG core 5 to notify the NG core 5 that UE 1 has changed its cell and requests a path switch. The NR path switch request message may include a path switch type information element (IE) indicating a path switch from LTE to NR. For example, the path switch type IE is set to "LTEtoNR". The NR path switch request message may also include a list of EPS bearers of UE 1 that have been switched to the cell of the target NR NB 3.

[0105] In step 208, the control node (e.g., CPF) in the NG core 5 performs a process for creating a bearerless session. Specifically, the control node determines that it is necessary to relocate the packet transmission node (or gateway) used by UE 1, and then selects the target transmission node (or gateway) used by the NG system in the NG core 5. The target transmission node (or gateway) used by the NG system is a node corresponding to the S-GW in LTE. The control node sends a create session request message to the target transmission node (or gateway). The create session request message may include information for identifying one or more service data flows associated with each EPS bearer context (e.g., an SDF template or a traffic flow template (TFT)). For example, information for identifying one or more service data flows can be derived from the following message (e.g., a forward relocation request message), which is sent from the MME in the network slice instance corresponding to the EPC to which the LTE eNB 2 is connected to the control node in the network slice instance corresponding to the pure NG core to which the NR NB 3 is connected. The target transmission node (or gateway) allocates its local resources and sends a create session response message to the control node.

[0106] Note that in the case where the NG system supports bearer-based transport using bearers for each QoS level and for each PDU session, and without the need for relocation of the transport node, instead of the session creation process, in step 208, the control node in the NG core 5 can perform a bearer modification process.

[0107] In addition, in step 208, the control node (e.g., CPF) in the NG core 5 may select (or reselect) the network slice to which the UE 1 is to be connected after the switch. The control node in the NG core 5 may create the selected network slice instance. In the example, the control node in the NG core 5 may select the network slice used by UE 1 based on the QoS required by the EPS bearer or SDF of UE 1. Additionally or optionally, the NG core 5 may consider network slice assistance information. The network slice assistance information assists the control node (e.g., CPF) in the NG core 5 in selecting, configuring or authorizing a network slice. The network slice assistance information may be generated by the UE 1, the LTE eNB 2, or the EPC network slice instance within the NG core 5. For example, the NR handover confirmation for NR message sent from UE 1 to the target NR NB 3 (step 206) may include network slice assistance information, and the target NR NB 3 may incorporate the received network slice assistance information into the NR path switching request message (step 207).

[0108] The network slice auxiliary information may, for example, indicate any one of the following or any combination thereof: the type of UE 1 (e.g., device type or UE category); the access purpose of UE 1 (e.g., UE usage type); the service type desired by UE 1 (e.g., requested / preferred service type or multi-dimensional descriptor (MDD)); the slice information selected by UE 1 (e.g., selected slice type, selected slice identification (ID) or selected network function (NF) ID); the slice information previously authorized by UE 1 (e.g., authorized slice type, authorized slice ID or authorized NF ID); the acceptable delay of UE 1 (e.g., allowed delay or tolerable delay). The service type may, for example, indicate the type of use case, such as broadband communication (e.g., enhanced mobile broadband: eMBB), high reliability / low latency communication (e.g., ultra-reliable and low latency communication: URLLC), M2M communication with a large number of connections (e.g., massive machine type communication: mMTC), or similar types thereof. The slice ID may, for example, indicate any one of the following or any combination thereof: slice instance information (e.g., network slice instance (NSI) ID); dedicated network information (e.g., dedicated core network (DCN) ID); and network domain name information (e.g., domain network name (DNN) ID). The NF ID may, for example, indicate an identifier of any one of the following or any combination thereof: a public network function (e.g., a public NF (CNF)); a public control plane function (e.g., a public control plane NF (CCNF)); a public user plane function (e.g., a public user plane NF (CUNF)); and a data gateway (e.g., a data network gateway (DN GW)).

[0109] In step 209, the control node in the NG core 5 sends an NR path switch request confirmation message to the target NRNB 3. The NR path switch request confirmation message may include core network information (e.g., NG core information). The core network information (e.g., NG core information) may include flow information or slice information, or both. The flow information relates to at least one session (i.e., PDU session) established in a bearerless network (i.e., NG system) to transmit at least one packet flow (i.e., PDU flow) of UE 1. The flow information includes: a flow identifier (e.g., PDU flow ID); an address of a transmitting node in the NG core 5 (e.g., a transport layer address) and an uplink (UL) session endpoint identifier (SEID); and flow QoS parameters. The session endpoint identifier (SEID) may be, for example, a tunnel endpoint identifier (TEID) or a network function (or node) identifier (NF ID). The TEID may be, for example, a GTP-TEID or a GRE-TEID.

[0110] The flow information may also indicate the mapping between the EPS bearers and PDU flows used by UE 1. For example, the flow information may indicate one or more SDFs mapped to each EPS bearer of UE 1 and a flow identifier (e.g., PDU flow ID) assigned to each of the one or more SDFs. The flow information may also include priority information (e.g., a priority indicator), flow type information (e.g., a flow type indicator), or a flow level. The priority information may, for example, indicate a relative priority order between multiple flows or an absolute priority order of each flow. The flow type information may, for example, indicate which use case or which service the flow corresponds to. In addition, the flow level may, for example, indicate one of the predefined flow types (e.g., lossless, delay tolerant, delay sensitive, and mission critical).

[0111] The slice information includes information related to at least one of the following: the network slice included in the NG core 5 to which UE 1 will be connected (or to which UE 1 is to be connected) after switching; the network slice included in the NG core 5 to which UE 1 is allowed to be connected; and the network slice included in the NG core 5 to which UE 1 can be connected.

[0112] The slice information may include identification information of the slice (i.e., network slice: NS) determined (or selected) for UE 1, identification information of the network node (NF), or type information of the slice, or any combination thereof. The slice identification information may be, for example, a slice ID, an NSI ID, an MDD, a DCN ID, or a DNN, or any combination thereof. The identification information of the network node may include, for example, an NF ID, a CNF ID, a CCNF ID, a slice-specific control plane NF (SCNF) ID, a CUNF ID, a slice-specific user plane NF (SUNF) ID, a UPF ID, or a DN GW ID, or any combination thereof. The slice type information may include, for example, a slice type indicating any one or any combination of a service type, a service category, and a use case. Additionally or optionally, the slice type information may include a tenant ID indicating a use case or a subscription contract (subscription group, for example, a home UE or a roaming UE). The slice type information may include an MDD containing a slice type and a tenant ID as its elements. Note that the content of the above-mentioned slice information may be specified for each network slice. Therefore, in the case where UE 1 wants to connect to multiple network slices at the same time, the slice information may include multiple groups of information items corresponding to the number of network slices to which UE 1 wants to connect.

[0113] The slice information may also include a mobility level or a session level, or both. The mobility level may indicate one of the predefined mobility levels (e.g., high mobility, low mobility, and no mobility). For example, high mobility means that the geographical area in which the network slice supports the mobility of UE 1 (or permits movement to UE 1) is larger than that of low mobility, and the level required for the continuity of the service (or PDU session) during switching is higher. No mobility means that the network slice supports the mobility of UE 1 (or permits movement to UE 1) only in a very limited geographical area. The mobility level may be specified for each UE, or the mobility level may be specified for each network slice. The session level may indicate one of the predefined session types (e.g., session pre-setup, session post-setup, and PDU-free session). For example, in order to maintain the service (or PDU session) during mobility as in the case of existing handover, the session pre-setup may indicate that a PDU session needs to be established before the UE completes the movement to the target (i.e., cell, beam, etc.). In contrast, the session post-setup may indicate that the PDU session can be established after the UE has moved to the target. A session level may be specified for each PDU session. The mobility level and the session level may be included in the slice type. In other words, the slice type may include multiple attributes including the mobility level and the session level. The above-mentioned flow information may include the mobility level or the session level, or both.

[0114] In step 210, the target NR NB 3 sends an NR DL information transfer message carrying NAS information (e.g., slice information and flow information) received from the NG core 5 to the UE 1.

[0115] In accordance with Figure 2A and 2B After the illustrated process completes the handover, the path illustrated below may be used for data transmission for UE 1. In the case where the NG system including the NR NB 3 and the NG core 5 supports bearer-based transmission in the NG core 5 and uses a bearer (e.g., an NG-EPS bearer) for the UE 1 after the handover, both the uplink path and the downlink path may include, for example, a path (e.g., a GTP tunnel or a GRE tunnel) between the source (or old) S / P-GW and the target (or new) user plane function (e.g., CUNF) in the NG core 5. Specifically, the S / P-GW may transmit downlink data to the user plane function (e.g., CUNF) in the NG core 5, and the user plane function (e.g., CUNF) in the NG core 5 may transmit uplink data to the S / P-GW.

[0116] In contrast, in the case where no bearer (e.g., NG-EPS bearer) is used for UE 1 after switching, for example, CUNF can relay between the source (or old) S / P-GW and the target (or new) user plane function (e.g., SUNF with NW slicing function). Specifically, the S / P-GW can transmit downlink data to the CUNF in the NG core 5, and then the CUNF can transmit the downlink data to another UNF with flow control function. Optionally, data can be transmitted directly between the S / P-GW and the SUNF without going through the CUNF. The above-mentioned data transmission path after switching can also be used in other switching processes described below.

[0117] Figure 3A and 3B Shown for Figure 1 Another example of the process of switching UE 1 from the LTE system to the NG system in the structural example of the wireless communication network shown. Figure 3A shows the switching preparation phase and the switching execution phase, and Figure 3B The handover completion stage is shown. Figure 2A and 2B In the process shown, the target NR NB 3 receives core network information (e.g., flow information or slice information or both) from the NG core 5 in the handover completion phase (step 209) performed after the UE 1 has been connected to the target NR NB 3. Figure 3A and 3BIn the process shown, the target NR NB 3 receives core network information (e.g., flow information or slice information or both) from the NG core 5 in the handover preparation phase (step 304) before the LTE eNB 2 issues a handover instruction to the UE 1. The following mainly describes this difference.

[0118] The processing in steps 301 and 302 is the same as Figure 2A The processing in steps 201 and 202 is the same. In step 303, the target NR NB 3 sends a handover preparation request message to the NG core 5 in response to receiving the NR handover request message (step 302).

[0119] The handover preparation request message in step 303 may include a handover type information element (IE) indicating a handover from LTE to NR. For example, the handover type IE is set to "LTEtoNR". The handover preparation request message may also include a list of NG EPS bearers of UE 1 to be transferred to the cell of the target NR NB 3.

[0120] In step 304, the NG core 5 determines that the type of handover is an inter-RAT handover to the NR (or NG system) based on the received handover preparation request message. Then, the NG core 5 sends a handover preparation request confirmation message including one or both of the core network information and the security-related information to the target NR NB 3. The target NR NB 3 and the UE 1 use the core network information and the security-related information to perform radio resource settings and security-related settings to communicate with the UE 1 in the NG system. Several specific examples of the core network information are described below.

[0121] In an example, the core network information may include slice information. The slice information includes information related to at least one of the following: a network slice included in the NG core 5 to which the UE 1 will be connected (or to which the UE 1 is to be connected) after the handover; a network slice included in the NG core 5 to which the UE 1 is allowed to be connected; and a network slice included in the NG core 5 to which the UE 1 can be connected. The control node (e.g., CPF) in the NG core 5 determines (or selects) the network slice to which the UE 1 is to be connected after the handover. In an example, the control node (CPF) in the NG core 5 may select the network slice used by the UE 1 based on the QoS required by the EPS bearer or SDF of the UE 1. Additionally or optionally, the NG core 5 may consider network slice assistance information. The network slice assistance information assists the control node (e.g., CPF) in the NG core 5 in selecting, configuring or authorizing a network slice. The network slice assistance information may be generated by the UE 1, the LTE eNB 2, or the EPC network slice instance within the NG core 5. For example, the UE 1 may send the network slice assistance information to the LTE eNB 2 in step 301. The network slice assistance information may be NAS information and may be included in a measurement report sent from UE 1 to LTE eNB 2. In step 302, the source LTE eNB 2 may send the network slice assistance information received from UE 1 to the target NR NB 3.

[0122] In another example, the core network information may include flow information. The flow information is related to at least one session (i.e., PDU session) established in a bearerless network (i.e., NG system) to transmit at least one packet flow (i.e., PDU flow) of UE 1. With respect to each packet flow (i.e., each PDU flow) of UE 1, the flow information includes: a flow identifier (e.g., PDU flow ID); an address of a transmitting node in the NG core 5 and an uplink (UL) session endpoint identifier (SEID); and flow QoS parameters. The session endpoint identifier (SEID) may be, for example, a tunnel endpoint identifier (TEID) or a network function (or node) identifier (NF ID). The TEID may be, for example, a GTP-TEID or a GRE-TEID.

[0123] The flow information may also indicate a mapping between EPS bearers and PDU flows used by UE 1. For example, the flow information may indicate one or more SDFs mapped to each EPS bearer of UE 1 and a flow identifier (e.g., PDU flow ID) allocated to each of the one or more SDFs. The flow information may also include priority information (e.g., a priority indicator), flow type information (e.g., a flow type indicator), or a flow level.

[0124] On the other hand, the security-related information may include non-access stratum (NAS) security configuration information (security configuration) used between the NG core 5 and the UE 1 in the NG system. The NAS security configuration information includes, for example, a NAS security algorithm including encryption and integrity protection. The NAS security configuration information may be a NAS security transparent container IE. That is, the NAS security configuration information (or NAS security transparent container IE) is transparently sent from the target NR NB 3 to the UE 1 via the source LTE eNB 2.

[0125] The security related information also includes the security parameters to be used by the target NR NB 3 to derive the access stratum (AS) security key. These security parameters include the basic key (i.e., the same as the K of LTE) used to derive the security key (or temporary key) used by the AS layer. eNB The next hop parameter (NH) and the next hop chain counter parameter (NCC) are used to derive K according to the key derivation algorithm in the vertical direction. eNB These security parameters may also include UE security capabilities related to the NG RAT or NG system. The UE security capabilities indicate the encryption and integrity protection algorithms implemented in the UE 1.

[0126] The core network information included in the confirmation response (switching preparation request confirmation) to the switching preparation request in step 304 may include either or both of the two examples described above (ie, slice information and flow information).

[0127] In step 305, the target NR NB 3 generates a UE context and allocates resources in response to receiving a handover preparation request confirmation message including one or both of the core network information and the security-related information.

[0128] In the case where the core network information included in the handover preparation request confirmation message includes slice information, the target NRNB 3 may operate as follows. The target NR NB 3 may perform admission control based on the core network information including the slice information. For example, the target NR NB 3 may determine whether to accept the bearer or the flow for each bearer or for each flow. Additionally or optionally, the target NR NB 3 may perform admission control for each network slice to which the UE 1 is to be connected based on the slice information. Note that NR NB 3 may determine whether NR NB 3 can accept each network slice. In the case where there is a network slice that NR NB 3 cannot accept (or does not accept), NR NB 3 may map the network slice to a specific network slice (e.g., a default network slice), or may connect the network slice to a specific NF (e.g., CUPF). Optionally, NRNB 3 may determine that NR NB 3 has failed to accept the network slice.

[0129] Additionally or optionally, the target NR NB 3 may generate (or derive from the slice information) radio resource configuration information (e.g., radio parameters) required by UE 1 to establish a radio connection (e.g., RRC connection or radio bearer) associated with an NG system supporting network slicing based on the slice information. The radio resource configuration information may include at least one parameter included in the slice information.

[0130] The radio resource configuration information derived from the slice information may include radio (or RAN) parameters for each network slice (or each use case). Use cases include, for example, enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable and low latency communication (URLLC). The radio parameters for each network slice (or each use case) may be basic physical channel parameters or basic layer 2 / layer 3 (L2 / L3) configuration. Basic physical channel parameters may include, for example, frame / subframe structure, transmission time interval (TTI) length, subcarrier spacing, and physical random access channel (PRACH) resources. PRACH resources may be either or both of the preamble index and time / frequency resources. The basic L2 / L3 configuration may include, for example, a frame / subframe mode and a configuration of the L2 protocol sublayer (L2 configuration, for example, PDCP config, RLC config, or MAC config).

[0131] Additionally or optionally, in RRC signaling that specifies (or indicates) wireless resource configuration information derived from slice information, at least one of the following differs between slices: message structure; format of information element (IE); parameter value; and ASN.1 (Abstract Syntax Notation One) encoding and decoding objects that represent the structure definition of the information.

[0132] In the case where the core network information included in the handover preparation request confirmation message includes flow information, the target NRNB 3 may operate as follows. The target NRNB 3 may consider the flow information to create a UE context and radio resource configuration information. Specifically, the target NRNB 3 may generate a UE context including information related to a packet flow (i.e., a PDU flow) and a security context based on the flow information. In addition, the target NRNB 3 may generate (or derive from the flow information) the radio resource configuration information required by the UE 1 to establish a radio connection (e.g., an RRC connection or a radio bearer) associated with a bearerless network (i.e., an NG system) based on the flow information. The radio resource configuration information may include at least one parameter included in the flow information. The radio resource configuration information may include system information (e.g., a system information block: SIB) in the cell (or mobility area or beam coverage area) of the target NRNB 3, a public radio resource configuration of the UE (e.g., a public resource configuration), or a dedicated radio resource configuration of the UE (e.g., a dedicated resource configuration). The radio resource configuration information may also include information indicating the mapping between bearers (e.g., EPS bearers or data radio bearers (DRBs)) in the cell of the source LTE eNB 2 and flows (e.g., PDU flows) to be established in the cell of the target NR NB 3.

[0133] As already explained, the NG system including the NR NB 3 and the NG core 5 may be configured to support bearer-based transmission using bearers for each QoS level and for each PDU session, or may be configured to identify data flows (e.g., PDU flows) in a bearer to perform QoS processing (e.g., packet discard) for each data flow (e.g., for each PDU flow). For example, the NRNB 3 may associate a bearer (e.g., NG3 bearer) configured between the NR NB 3 and the user plane function in the NG core 5 with a radio bearer, perform packet forwarding between the bearer (e.g., NG3 bearer) and the radio bearer, and perform QoS processing (e.g., packet discard) for each data flow (e.g., PDU flow) in the bearer.

[0134] In this case, the above-mentioned flow information may indicate an association between a bearer (e.g., NG-RAB or NG3 bearer) used by UE 1 and one or more packet flows (i.e., PDU flows) of UE 1 transmitted via the bearer. In other words, the control node (e.g., CPF) in the NG core 5 may send the flow information to NR NB 3 to notify NR NB 3 of the association between the bearer (e.g., NG-RAB or NG3 bearer) used by UE 1 and one or more packet flows (i.e., PDU flows) of UE 1 transmitted via the bearer. NR NB 3 may receive the flow information from the control node in the NG core 5, and then perform QoS processing (e.g., packet discard) for each data flow (e.g., PDU flow) in the bearer (e.g., NG3 bearer) configured between NR NB 3 and the user plane function in the NG core 5 based on the received flow information.

[0135] In the case where the handover preparation request confirmation message includes security-related information, the target NR NB 3 may operate as follows. As described above, the security-related information includes NAS security configuration information (e.g., NAS security transparent container IE) and security parameters of AS security. The target NR NB 3 may incorporate the NAS security configuration information (e.g., NAS security transparent container IE) into a transparent container to be sent to UE 1. Additionally or optionally, the target NR NB 3 may select an AS security algorithm based on the UE security capabilities included in the security parameters. The AS security algorithm includes encryption algorithms for radio resource control (RRC) and user plane (UP), and also includes an integrity protection algorithm for RRC. In addition, the target NR NB 3 may perform an AS security algorithm based on a basic key obtained from the security parameters (i.e., K with LTE) by using the selected security algorithm. eNB The corresponding key) is used to derive the temporary keys used for RRC encryption, UP encryption and RRC integrity protection.

[0136] The target NR NB 3 generates a target-to-source transparent container (e.g., RRC connection reconfiguration) to be sent to UE 1. The target-to-source transparent container, for example, includes a handover command message including an RRC connection reconfiguration message and other RRC messages. Then, as a response to the handover request, the target NR NB 3 generates a confirmation response (e.g., NR handover request confirmation) message including a target-to-source transparent container and including the following core network context information (e.g., NG core context IE), wherein the core network context information includes core network information. The target NR NB 3 sends the NR handover request confirmation message to the source LTE eNB 2 on the direct base station interface 101 (e.g., X3 interface). The target-to-source transparent container, for example, includes the radio resource configuration information (e.g., radio parameters) set by the target NR NB 3, the identifier of the AS security algorithm selected by the target NR NB 3, and the NAS security configuration information. The core network context information (e.g., NG core context) can be transparently sent to UE 1 via the source LTE eNB 2. Additionally or optionally, part or all of the core network context information may be included in a target to source transparent container. The NR handover request confirmation message may also include the above-mentioned "accepted NE-RAB list" information element (IE). The source LTE eNB 2 starts data forwarding for the bearer or flow (e.g., PDU flow) specified by the "accepted NE-RAB list" IE.

[0137] The processing of step 306 is Figure 2A In step 307, in response to receiving the RRC message containing the handover command message, UE 1 moves to the target RAN (i.e., NG RAN) and performs handover according to the transparent container (e.g., radio resource configuration information, AS security algorithm, and NAS security configuration information) provided by the handover command message. The processing of step 308 is the same as Figure 2A The processing of step 206 is the same as that of step 206.

[0138] In step 309, the NG core 5 performs a bearerless session creation process or a bearer modification process. In other words, the control node in the NG core 5 starts a bearerless session creation process or a bearer modification process for UE 1 in response to receiving the handover preparation request message in step 303. Specifically, the control node in the NG core 5 starts a bearerless session creation process or a bearer modification process for UE 1 before the path switching request from the target NR NB 3 (step 310). Figure 2B The bearerless session creation or bearer modification in step 309 is performed in the same manner as the bearerless session creation or bearer modification in step 208.

[0139] In step 310, the target NR NB 3 sends an NR path switching request message to the NG core 5. In step 311, the control node in the NG core 5 performs a flow modification process, thereby completing the inter-RAT switching process. For example, the control node in the NG core 5 may send a modify flow request message for each session (i.e., for each PDU session) to the transmission node in the NG core 5. The modify flow request message may include a flow identifier (e.g., a PDU flow ID), and may also include an address of the target NR NB 3 and a downlink (DL) session endpoint identifier (SEID). The session endpoint identifier (SEID) may be, for example, a tunnel endpoint identifier (TEID). The transmission node in the NG core 5 may send a modify flow response message to the control node in the NG core 5. In step 312, the control node in the NG core 5 sends an NR path switching request confirmation message to the target NR NB 3.

[0140] Figure 4 4 is a flow chart showing a process 400 as an example of a method performed by the target NR NB 3. In step 401, the target NR NB 3 receives a handover request message from the source LTE eNB 2 on the direct inter-base station interface 101. The handover request message is related to the handover of the UE 1 from the LTE system to the NG system. Step 401 corresponds, for example, to Figure 2A Step 202 or Figure 3A Step 302.

[0141] In step 402, the target NR NB 3 receives slice information or flow information or both from the core network (ie, the NG core 5). Step 402 corresponds to, for example, Figure 2B Step 209 or Figure 3A Step 304.

[0142] In step 403, the target NR NB 3 controls the communication of UE 1 based on at least one of the slice information and the flow information. For example, the target NR NB 3 may generate radio resource configuration information based on at least one of the slice information and the flow information, and send the radio resource configuration information to UE 1. For example, based on the slice information, the target NR NB 3 may select a network slice to which NR NB 3 sends a control plane message related to UE 1. For example, the target NR NB 3 may forward UL user data (e.g., PDU flow) of UE 1 to the NG core 5 based on the endpoint information included in the flow information. For example, the target NR NB 3 may perform resource scheduling for UE 1 based on the flow QoS parameters included in the flow information.

[0143] Figure 55 is a flow chart showing a process 500 as an example of a method performed by the source LTE eNB 2. In step 501, the source LTE eNB 2 sends a handover request message to the target NR NB 3 on the direct inter-base station interface 101. The handover request message is related to the handover of the UE 1 from the LTE system to the NG system. Step 501 corresponds, for example, to Figure 2A Step 202 or Figure 3A Step 302.

[0144] In step 502, the source LTE eNB 2 receives a handover request confirmation message including a transparent container (e.g., RRC connection reconfiguration) from the target NR NB 3 on the direct inter-base station interface 101. Step 502 corresponds to, for example, Figure 2A Step 203 or Figure 3A Step 305. The transparent container includes, for example, the radio resource configuration information set by the target NR NB 3, the identifier of the AS security algorithm selected by the target NR NB 3, and the NCC value or NAS security configuration information.

[0145] In step 503, the source LTE eNB 2 sends a mobility command message (eg, a handover command message) to the UE 1, which contains the transparent container received from the target NR NB 3 and indicates handover to the bearerless network. Step 503 corresponds to Figure 2A Step 204 or Figure 3A Step 306.

[0146] Figure 6 is a flow chart illustrating a process 600 as an example of a method performed by a core network (ie, NG Core 5). Figure 6 The processing shown may be performed by a single control node in the NG core 5, or may be performed by two control nodes in the NG core (i.e., the source MME and the target control node). In step 601, the NG core 5 receives a message (e.g., a handover preparation request message or an NR path switch request message) from the NRNB 3 indicating a handover or path switch from the LTE system to the NG system. Step 601 corresponds to Figure 2B Step 207 or Figure 3A Step 303.

[0147] In step 602, the NG core 5 sends the slice information or the flow information or both to the target NR NB 3. Step 602 corresponds to, for example, Figure 2B Step 209 or Figure 3A Step 304.

[0148] Figure 7700 is a flow chart showing an example of a process 700 as a method performed by UE 1. In step 701, UE 1 receives a mobility command message (e.g., a handover command message) from source LTE eNB 2. The mobility command message contains a transparent container (e.g., an RRC connection reconfiguration) sent from target NR NB 3. The transparent container, for example, contains radio resource configuration information, an AS security algorithm, and an NCC value or NAS security configuration information. Step 701 corresponds to, for example, Figure 2A Step 204 or Figure 3A Step 306.

[0149] In step 702, UE 1 establishes a wireless connection with a target NR NB 3 associated with the NG system according to the information included in the received transparent container. Step 702 corresponds to, for example, Figure 2A Steps 205 and 206 or Figure 3A Steps 307 and 308.

[0150] In this embodiment, the network may be configured to enable UE 1 to know in advance whether the handover target cell (i.e., NR cell) supports network slicing. For example, NR NB 3 may broadcast system information including network slicing support information (e.g., system information block type-x: SIBx, e.g., x=1), which explicitly or implicitly indicates that network slicing is supported in the NR cell (or can be connected to an NG core capable of providing network slicing). In order to indicate the supported network slices, the network slicing support information sent explicitly may also include the type of supported services (e.g., supported service types) or the type of supported slices (e.g., supported slice types). In contrast, the implicitly sent network slicing support information may include information related to radio resource configurations that are different for each network slice. UE 1 may know that network slicing is supported in the cell when it detects that at least a portion of the received radio resource configuration is specified for each network slice. The information related to the radio resource configuration may include configuration information related to physical resources or system configuration information or both. The configuration information related to physical resources may indicate at least one of a code, a time, a frequency, and a RACH preamble sequence (group). The system configuration information may indicate at least one of a subcarrier spacing, a sampling rate, a TTI, and a subframe / frame format type. The network slicing support information may be sent as NAS layer information, or may be sent as AS layer information. In the former case, the AS layer (ie, RRC) of UE 1 receives the information and transmits the information to the NAS layer.

[0151] The detailed process of switching from the LTE system to the NG system according to this embodiment is not limited to the above specific examples. For example, the names of the messages in the switching process are not limited to the names of the messages shown in the above examples. In the above examples of the switching process, the order of the messages can be changed, and some of the messages can be omitted. In addition, the messages may include one or more additional messages.

[0152] As will be understood from the above description, the various handover processes from the LTE system to the NG system described in this embodiment are inter-RAT handover processes involving the transmission of handover signaling messages on a direct inter-base station interface. In these handover processes, the target NR NB 3 is configured to receive one or both of the slice information and the flow information from the core network (i.e., the NG core 5), and use the received information to control the communication of the UE 1. In this way, the target NR NB 3 can help to continue the communication of the UE 1 in the connected state that has been switched from the LTE system to the NG system.

[0153] Second embodiment

[0154] This embodiment provides a variation of the method for switching UE 1 from the LTE system to the NG system according to the first embodiment. Figure 8 Shown for Figure 1 An example of a process of switching UE 1 from an LTE system to an NG system is shown in the structural example of a wireless communication network. Figure 8 The switching process shown provides Figure 2A and 2B The details of the switching process shown and the modifications to the switching process. Specifically, Figure 8 The structure within the NG core 5 and the selection of network slices performed by the NG core 5 are specifically shown.

[0155] Figure 8 The NG core 5 shown includes a public network function (NF) 51, a network function used by network slice A (NF for slice A) 52, a network function used by network slice B (NF for slice B) 53 and a home subscriber server (HSS) 54.

[0156] Note that each network element (i.e., NF) is an integral part of a network slice. Each network slice includes the network functions (NFs) required to provide the required telecommunication services and network capabilities. Each network element (NF) is a processing function in the network and defines functional behaviors and interfaces. Each network element can be implemented as a network element on dedicated hardware, a software instance running on dedicated hardware, or a virtualized function instantiated on an appropriate platform.

[0157] Each network slice may be identified by a network slice specific instance ID (NSI-ID). Each network function (NF) may be identified by a network function ID (NF ID). In the presence (or use) of a common control plane network function (common CP NF), the NSI-ID may be a combination of the common CP NF ID and a slice specific ID (i.e., the NF ID of the selected slice).

[0158] Figure 8 The public NF 51 shown includes a control plane network function (CP NF). The public NF 51 may also include a user plane network function (UP NF). The NF 52 for slice A includes a UP NF and may also include a CP NF. Similarly, the NF 53 for slice B includes a UP NF and may also include a CP NF.

[0159] Figure 8 An example is shown in which a slice selection function (SSF) is located at the same location as the public NF 51. However, the SSF may be located at a location separate from the public NF 51. In this case, the public NF 51 exchanges messages with the SSF. The SSF selects a network slice to be associated with UE 1. For example, the SSF may associate UE 1 with a default network slice. Additionally or alternatively, the SSF may associate UE 1 with a network slice (or slice type) that UE 1 has specified. In addition, the SSF may provide a NAS node selection function (NNSF) to select a CP NF (or CP NFID) corresponding to the selected slice. Note that the default network slice may be configured per public land mobile network (PLMN), per RAT, per UE usage type, per service type, or per slice type.

[0160] The allocation of one or more packet flows of UE 1 to a network slice may be performed according to one of the three examples described below. In the first example, the NG system including the NR NB 3 and the NG core 5 supports bearer-based delivery using bearers for each QoS level and for each PDU session. The bearers in the NG system may be referred to as NG-EPS bearers, and the radio access bearers in the NG system may be referred to as NG-RABs. In the first example, each bearer is allocated to a network slice. In some implementations, the common NF 51 communicates with a slice-specific user plane NF (SUNF) of the network slice selected for the UE 1, and sets the bearer of the UE 1 in the SUNF.

[0161] In the second example, similar to the first example, the NG system including the NR NB 3 and the NG core 5 supports bearer-based delivery using bearers for each QoS level and for each PDU session. The bearers in the NG system can be used to transmit multiple packet flows (e.g., PDU flows). In the second example, the NG system is configured to identify the data flows (e.g., PDU flows) in the bearer to perform QoS processing (e.g., discard packets) for each data flow (e.g., for each PDU flow). In the second example, each packet flow (e.g., PDU flow) of the UE 1 is allocated to a network slice for each flow (e.g., for each PDU flow).

[0162] In the third example, the NG system including the NR NB 3 and the NG core 5 supports flow-based transmission of user data. In the third example, a network slice is configured for each PDU session of the UE 1. In other words, a group of packet flows (e.g., PDU flows) included in one PDU session are allocated to the network slice as a whole.

[0163] In step 801, UE 1 has been handed over from source LTE eNB 2 to target NR NB 3 and is in a connected state (i.e., RRC_Connected) in the cell of target NR NB 3. UE 1 sends network slice assistance information to target NR NB 3. As already explained, the network slice assistance information may, for example, indicate the type of UE 1, the service desired by UE 1, the acceptable delay of UE 1, or any combination thereof. The network slice assistance information may be NAS information and may be included in a measurement report sent from UE 1 to LTE eNB 2. UE 1 may use an RRC connection reconfiguration complete message (e.g., Figure 2A The network slice assistance information may be sent by UE 1 in step 206), UL information transmission message or another RRC message. Optionally, the sending of the network slice assistance information by UE 1 may be omitted.

[0164] Step 802 corresponds to Figure 2B Step 207. That is, the target NR NB 3 sends the NR path switching request message to the NG core 5. The NR path switching request message includes the EPS radio access bearer (E-RAB) QoS information element (IE). The E-RAB QoS IE indicates the QoS of the E-RAB of UE 1 (for example, QoS class identification (QCI), allocation and retention priority (ARP)). The NR path switching request message may also include network slice assistance information sent from the NAS layer of UE 1 (step 801).

[0165] In step 803, if necessary, the public NF 51 performs authentication of the UE 1. The authentication includes confirmation (slice authorization) of the slices allowed (or authorized) to the UE 1. In the slice authorization, the public NF 51 can decide / judge whether the UE 1 is allowed for each slice.

[0166] In step 804, the public NF 51 selects a slice. In other words, the public NF 51 selects a network slice to be associated with the UE 1. Figure 8 In the example shown, the public NF 51 selects slice A for UE 1. The slice selection of step 804 may be performed for each ongoing service performed by UE 1 or for each service (e.g., EPS bearer / E-RAB, IP flow) requested by UE 1. As already explained, the slice selection of step 804 may be performed by an SSF located at a location separate from the public NF 51.

[0167] Step 805 corresponds to Figure 2B Step 208. Public NF 51 communicates with the UP NF (i.e., NF 52 for slice A) for the slice selected for UE 1 (slice A in this example) to create a bearer-free session in the selected slice. Note that in the case where the NG system supports bearer-based transmission of user data and where relocation of the transmission node is not required, public NF 51 may perform a bearer modification procedure instead of a session creation procedure.

[0168] Step 806 corresponds to Figure 2B Step 209. The public NF 51 sends the NR path switch request confirm message to the target NR NB 3. The CP NF of the selected slice (e.g., NF 2 for slice A) can send the NR path switch request confirm message to the target NR NB 3 on behalf of the public NF 51.

[0169] The NR path switching request confirmation message of step 806 includes information related to the network slice selected by the public NF 51 (or SSF) (i.e., Slice Information Information Element (IE)). The slice information IE may, for example, contain an NSI ID indicating the selected network slice, an NF ID or a multi-dimensional descriptor (MDD) indicating the selected network function (NF), or any combination thereof. The MDD may be provided by the UE in the RRC signaling layer and the NAS signaling layer. The MDD indicates a tenant ID and a service descriptor / slice type. The service descriptor / slice type indicates a service or use case associated with the UE 1 or with the selected network slice (e.g., eMBB, mMTC, URLLC, or critical communication (CriC)).

[0170] Step 807 corresponds to Figure 2B Step 210. The target NR NB 3 sends an NR DL Information Transfer message carrying the Slice Information IE received from the NG Core 5 to the UE 1.

[0171] Fig. 9A and 9B is used in Figure 1 An example of a process of switching UE 1 from an LTE system to an NG system is shown in the structural example of a wireless communication network. Fig. 9A and 9B The switching process shown provides Figure 3A and 3B The details of the switching process shown and the modifications to the switching process. Specifically, Fig. 9A and 9B The structure in the NG core 5 and the selection of network slices performed by the NG core 5 are specifically shown. Figure 8 The process shown is similar to Fig. 9A and Fig. 9B The differences between the processes shown.

[0172] In step 901, UE 1 is connected to LTE eNB 2 and is in a connected state (ie, RRC_Connected). UE 1 sends network slice assistance information to LTE eNB 2. UE 1 may send the network slice assistance information using an RRC connection reconfiguration complete message, a UL information transfer message, or another RRC message.

[0173] Step 902 corresponds to Figure 3A Step 302. That is, the source LTE eNB 3 sends an NR handover request message to the target NR NB 3. The NR handover request message includes the E-RAB QoS IE. The E-RAB QoS IE indicates the QoS of the E-RAB of UE 1 (for example, QoS class identification (QCI), allocation and retention priority (ARP)). The NR handover request message may also include network slice assistance information sent from the NAS layer of UE 1 (step 901).

[0174] Step 903 corresponds to Figure 3A Step 303. That is, the target NR NB 3 sends a handover preparation request message to the NG core 5. The handover preparation request message includes the E-RAB QoS IE received from the source LTE eNB 2. The handover preparation request message may also include the network slice assistance information received from the source LTE eNB 2 (step 801).

[0175] The processing of steps 904 and 905 is the same as Figure 8The processing of steps 803 and 804 in is the same. Step 906 corresponds to Figure 3A That is, the public NF 51 sends a handover preparation request confirm message to the target NR NB 3. The handover preparation request confirm message includes information related to the network slice selected by the public NF 51 (or SSF) (ie, slice information IE).

[0176] Step 907 corresponds to Figure 3A Step 305. That is, the target NR NB 3 sends the NR handover request confirmation message to the source LTE eNB 2. The transparent container contained in the NR handover request confirmation message may include the slice information IE sent from the public NF 51.

[0177] Step 908 corresponds to Figure 3A Step 306. That is, the source LTE eNB 3 sends a radio resource control (RRC) message including the following handover command message to the UE 1, wherein the handover command message includes the transparent container generated by the target NR NB 3. The RRC message may be, for example, a mobility command message or an RRC connection reconfiguration message from EUTRA. As described above, the transparent container sent to the UE 1 may include the slice information IE.

[0178] Steps 909 and 910 correspond to Figure 3A Steps 307 and 308 of the protocol. That is, UE 1 performs handover to the target NR NB 3 (step 309) and sends an NR handover confirmation for the NR message to the target NR NB 3 (step 910). The message in step 910 may be an NR RRC connection reconfiguration complete message. The message in step 910 may include a slice information IE. The slice information IE includes an identifier (e.g., NSI-ID, NF ID, or MDD) for identifying the network slice selected for UE 1. The slice information IE may be NAS information or RRC information.

[0179] During the handover completion phase, Fig. 9B Any of Option 1 (ie, steps 911A, 912A, and 913A) and Option 2 (ie, steps 911B, 912B, and 913B) shown.

[0180] In option 1, the target NR NB 3 sends an NR path switch request message to the public NF 51 (step 911A). The NR path switch request message may include a slice information IE. Step 911A corresponds to Figure 3B Step 310.

[0181] Step 912A corresponds to Figure 3BStep 311 of UE 1. Public NF 51 communicates with the UP NF (i.e., NF 52 for slice A) for the slice selected by UE 1 (slice A in this example) to create a bearer-free session in the selected slice. In the case where the NG system supports bearer-based transmission of user data and where relocation of the transmission node is not required, public NF 51 may perform a bearer modification procedure instead of a session creation procedure.

[0182] Step 913A corresponds to Figure 3B Step 312. The public NF 51 sends the NR path switch request confirm message to the target NR NB 3. On behalf of the public NF 51, the CP NF within the selected slice (i.e., the slice A NF 52) can send the NR path switch request confirm message to the target NR NB 3.

[0183] In contrast, in Option 2, the target NR NB 3 determines the network slice selected for UE 1 (i.e., slice A), and sends an NF path switch request confirmation message to the CP NF within the slice A NF 52 corresponding to slice A (step 911B). In some implementations, the target NR NB 3 may use the slice information IE received from UE 1 in step 910 to determine the network slice selected for UE 1. Optionally, the target NR NB 3 may store the slice information IE received from the NG core 5 in step 907 in association with the context of UE 1, and may use the stored slice information IE for the determination of step 911B.

[0184] Step 912B corresponds to Figure 3B Step 311 of the present invention. The CP NF within the slice A NF 52 communicates with the UPNF of the slice A NF 52 to create a bearer-free session. In the case where the NG system supports bearer-based transmission of user data and where relocation of the transmission node is not required, the slice A NF 52 may perform a bearer modification procedure instead of a session creation procedure. If necessary, the slice A NF 52 may communicate with the public NF 51.

[0185] Step 913B corresponds to Figure 3B Step 312. The CP NF in Slice A NF 52 sends the NR path switch request confirm message to the target NR NB 3.

[0186] Based on the handover process from the LTE system to the NG system according to the present embodiment, the NG core 5 may provide the target NR NB 3 with information (e.g., NSI-ID, MDD, NFID) related to the network slice selected by the public NF 51 for the UE 1. Thus, for example, the target NR NB 3 may identify the network slice selected for the UE 1. Additionally or alternatively, for example, the target NR NB 3 may use the information related to the network slice selected by the public NF 51 for the UE 1 to generate or derive information or parameters to be included in the handover command (i.e., transparent container (RRC connection reconfiguration)) and to be sent to the UE 1.

[0187] Third embodiment

[0188] This embodiment provides a method for switching UE 1 from an NG system to an LTE system. Fig. 10A and 10B Shown for Figure 1 An example of a process of switching UE 1 from an NG system to an LTE system is shown in the structural example of a wireless communication network. Fig. 10A shows the switching preparation phase and the switching execution phase, and Fig. 10B The handover completion phase is shown.

[0189] Fig. 10A and 10B The process shown is similar to "X2-based handover" in LTE in that it transmits a handover signaling message on the direct inter-base station interface 101 (e.g., X3 interface) during handover preparation (i.e., steps 1002 and 1003). However, in the case where only the handover signaling message on the direct inter-base station interface 101 is transmitted, the information required for the relocation of UE 1 from the NG system to the LTE system is insufficient. Fig. 10A and 10B In the process shown, the handover completion phase is improved to include signaling between the LTE eNB 2 and the NG core 5 (ie, steps 1007 and 1008) to obtain the information required for the relocation of the UE 1 from the NG system to the LTE system.

[0190] In step 1001, UE 1 is connected to NR NB 3 and is in a connected state (e.g., RRC_Connected). UE 1 receives a measurement configuration from NR NB 3, performs neighbor cell measurement and inter-RAT measurement including measurement of NG-RAN cells and E-UTRAN (LTE) cells according to the received measurement configuration, and sends a measurement report to NR NB 3.

[0191] In step 1002, NR NB 3 determines an inter-RAT handover to the cell of LTE eNB 2. When the inter-RAT handover is determined, NR NB 3 sends a handover request message to the target LTE eNB 2 on the direct inter-base station interface 101.

[0192] The handover request message in step 1002 may include a handover type information element (IE) indicating a handover from NR to LTE. For example, the handover type IE is set to "NRtoLTE".

[0193] The handover request message in step 1002 may also indicate an identifier and QoS parameters (eg, QCI, ARP) of a flow (eg, PDU flow) or bearer of UE 1 to be handed over.

[0194] The handover request message in step 1002 may also include a "handover preparation information to EUTRA" information element (IE). The "handover preparation information to EUTRA" IE may include security related information. The security related information includes security parameters to be used by the target LTE eNB 2 to derive the access layer (AS) security key. These security parameters include the basic key (i.e., the K key of LTE) used to derive the security key (or temporary key) used by the AS layer. eNB ), or includes parameters for deriving the basic key (e.g., {NH, NCC} pair). These security parameters may also include UE security capabilities related to the LTE RAT or LTE system. The UE security capabilities indicate the encryption and integrity protection algorithms implemented in UE 1.

[0195] For example, similar to the existing X2 handover process, the source NR NB 3 can derive K according to the unused {NH, NCC} pair based on the vertical key derivation algorithm. eNB* , and {K eNB *, NCC} pair is sent to the target LTE eNB 2. Optionally, the source NRNB 3 can derive the key from the current K eNB Derivation of K eNB* , and {K eNB *,NCC} pair is sent to the target LTE eNB 2.

[0196] In step 1003, the target LTE eNB 2 generates a UE context and allocates resources based on the handover request message. In the case where the NR handover request message in step 1003 includes security-related information, the target NR NB 3 may operate as follows. As described above, the security-related information includes security parameters for AS security. The target NR NB 3 may select an AS security algorithm based on the UE security capabilities included in the security parameters. The AS security algorithm includes encryption algorithms for radio resource control (RRC) and user plane (UP), and also includes an integrity protection algorithm for RRC. In addition, the target NR NB 3 may perform a UE handover based on a basic key (i.e., K for LTE) obtained from the security parameters by using the selected security algorithm. eNB )Derive temporary keys for RRC encryption, UP encryption and RRC integrity protection.

[0197] The target LTE eNB 2 generates a target-to-source transparent container (e.g., RRC connection reconfiguration) to be sent to UE 1. The target-to-source transparent container, for example, includes a handover command message (e.g., a handover command to EUTRA) including an RRC connection reconfiguration message and other RRC messages. Then, the target LTE eNB 2 generates a confirmation response (e.g., NR handover request confirmation) message including the target-to-source transparent container as a response to the handover request. The target LTE eNB 2 sends the NR handover request confirmation message to the source NR NB 3 on the direct base station interface 101. The target-to-source transparent container, for example, includes the radio resource configuration information (e.g., radio parameters) set by the target LTE eNB 2, the identifier of the AS security algorithm selected by the target NR NB 3, and the NCC value.

[0198] The handover request confirmation message may also include a list of bearers that are objects of downlink data forwarding (e.g., a list of bearers that are objects of data forwarding). The "List of bearers that are objects of data forwarding" IE, for example, includes the address and TEID used for user traffic data forwarding, and an identifier of the stream that is the object of data forwarding (e.g., a PDU stream). The address and TEID used for user traffic data forwarding may be the address and TEID used by the target NR NB 3 on the direct base station interface 101. The source NR NB 3 starts data forwarding for the bearer or stream (e.g., a PDU stream) specified by the "List of bearers that are objects of data forwarding" IE.

[0199] In step 1004, the source NR NB 3 sends a radio resource control (RRC) message including the following handover command message to the UE 1, wherein the handover command message includes a transparent container generated by the target LTE eNB 2. The RRC message may be, for example, a mobility command message or an RRC connection reconfiguration message from the NR.

[0200] In step 1005, in response to receiving the RRC message including the handover command message, UE 1 moves to the target RAN (i.e., E-UTRAN) and performs handover according to the transparent container (e.g., radio resource configuration information, AS security algorithm, and NCC value) provided by the handover command message. That is, UE 1 establishes a wireless connection with the target LTE eNB 2 associated with the LTE system. In step 1006, after successfully synchronizing to the target cell, UE 1 sends a handover confirmation for the EUTRA message to the target LTE eNB 2. The message of step 1006 may be an RRC connection reconfiguration complete message.

[0201] In step 1007, when UE 1 successfully accesses the target LTE eNB 2, the target LTE eNB 2 sends a path switching request message to the NG core 5 to notify the NG core 5 that UE 1 has changed its cell and requests path switching. The path switching request message may include a list of EPS bearers (or PDU flows) of UE 1 that have been switched to the cell of the target LTE eNB 2.

[0202] In step 1008, the control node (e.g., MME) in the NG core 5 performs a process for creating a bearer-based session. Specifically, the control node determines that the packet transmission node (or gateway) of UE 1 needs to be relocated, and selects a target transmission node (i.e., S-GW) in the NG core 5. The control node sends a create session request message to the target S-GW. The create session request message may include information for identifying one or more service data flows associated with each PDU flow context (e.g., SDF template or traffic flow template (TFT)). The target S-GW allocates its local resources and sends a create session response message to the control node.

[0203] In step 1009, the NG core 5 sends a path switch request confirmation message to the target LTE eNB 2. The path switch request confirmation message includes bearer configuration information. The bearer configuration information includes the address of the transmission node (after relocation) in the NG core 5 and the uplink (UL) tunnel endpoint identifier (TEID).

[0204] Note that in case the NG system supports bearer-based delivery of user data and in case relocation of the delivery node is not required, the control node in the NG core 5 may perform a bearer modification procedure in step 1008 instead of a session creation procedure.

[0205] Fig.11A and 11B Shown for Figure 1An example of a process of switching UE 1 from an NG system to an LTE system is shown in the structural example of a wireless communication network. Fig.11A shows the switching preparation phase and the switching execution phase, and Fig. 11B The handover completion stage is shown. Fig. 10A and 10B In the process shown in FIG. 1 , the target LTE eNB 2 receives the bearer configuration information from the NG core 5 in the handover completion phase (step 1009) performed after the UE 1 has connected to the target LTE eNB 2. Fig.11A and 11B In the process shown, the target LTE eNB 2 receives bearer configuration information from the NG core 5 in the handover preparation phase (step 1104) before the NR NB 3 issues a handover instruction to the UE 1. The following mainly describes this difference.

[0206] The processing of steps 1101 and 1102 is Fig. 10A The processing of steps 1001 and 1002 is the same. In step 1103, the target LTE eNB 2 sends a handover preparation request message to the NG core 5 in response to receiving the handover request message (step 1102).

[0207] The handover preparation request message of step 1103 may include a handover type information element (IE) indicating a handover from NR to LTE. For example, the handover type IE is set to "NRtoLTE". The handover preparation request message may also include a list of PDU flows of UE 1 to be switched to the cell of the target LTE eNB 2.

[0208] In step 1104, the NG core 5 determines that the type of handover is an inter-RAT handover to the LTE system based on the received handover preparation request message. Then, the NG core 5 sends a handover preparation request confirmation message including one or both of the core network information and the security-related information to the target LTE eNB 2. The target LTE eNB 2 uses the core network information and the security-related information to perform radio resource settings and security-related settings to communicate with the UE 1 in the LTE system.

[0209] In an example, the core network information may include bearer configuration information (e.g., bearer Config). The bearer configuration information is related to at least one EPS bearer to be configured for UE 1. The bearer configuration information includes: a bearer identifier (e.g., EPS bearer identity and E-RAB ID); an address and UL TEID of a transmission node in the NG core 5; and bearer QoS parameters (e.g., QCI, ARP). The bearer configuration information may indicate a mapping between EPS bearers and PDU flows used by UE 1.

[0210] On the other hand, the security-related information includes NAS security configuration information of the LTE system. The NAS security configuration information includes, for example, a NAS security algorithm including encryption and integrity protection. The NAS security configuration information may be a NAS security transparent container IE. That is, the NAS security configuration information (NAS security transparent container IE) is transparently sent from the target LTE eNB 2 to the UE 1 via the source NR NB 3.

[0211] The security related information also includes the security parameters to be used by the target LTE eNB 2 to derive the AS security key. These security parameters include the basic key (i.e., K for LTE) used to derive the security key (or temporary key) used by the AS layer. eNB ), or includes parameters for deriving the basic key (e.g., {NH, NCC} pair). These security parameters may also include UE security capabilities related to the LTE RAT or LTE system. The UE security capabilities indicate the encryption and integrity protection algorithms implemented in UE 1.

[0212] In step 1105, the target LTE eNB 2 generates a UE context and allocates resources based on the handover preparation request confirmation message including one or both of the core network information and the security-related information. In the case where the handover preparation request confirmation message includes security-related information, the target LTE eNB 2 may operate as follows. As described above, the security-related information includes NAS security configuration information (e.g., NAS security transparent container IE) and security parameters of AS security. The target LTE eNB 2 may incorporate the NAS security configuration information (e.g., NAS security transparent container IE) into a transparent container to be sent to UE 1. Additionally or optionally, the target LTE eNB 2 may select an AS security algorithm (i.e., an encryption algorithm for RRC and UP, and an integrity protection algorithm for RRC) based on the UE security capabilities included in the security parameters. In addition, the target LTE eNB 2 may select an AS security algorithm based on a basic key (i.e., K eNB )Derive temporary keys for RRC encryption, UP encryption and RRC integrity protection.

[0213] Then, the target LTE eNB 2 generates a transparent container (e.g., RRC connection reconfiguration) to be sent to the UE 1, and generates a handover command message (e.g., a handover command message to EUTRA) containing the transparent container. The transparent container, for example, contains the radio resource configuration information set by the target LTE eNB 2, the identifier of the AS security algorithm selected by the LTE eNB 2, and the NAS security configuration information. The target LTE eNB 2 sends the handover command message to the source NRNB 3 on the direct base station interface 101.

[0214] The processing of steps 1106 to 1108 is the same as the processing of steps 1004 to 1006 of Figure 10. In step 1109, the NG core 5 performs a bearer session creation process. In other words, the control node in the NG core 5 starts a bearer session creation process for UE 1 in response to receiving the handover preparation request message in step 1103. Specifically, the control node in the NG core 5 starts an EPS bearer creation process for UE 1 before the path switching request from the target LTE eNB 2 (step 1110). The bearer creation of step 1109 can be performed in the same manner as step 1008 of Figure 10.

[0215] In step 1110, the target LTE eNB 2 sends a path switching request message to the NG core 5. In step 1111, the control node in the NG core 5 completes the inter-RAT switching process by performing a bearer modification process. For example, the control node in the NG core 5 may send a modify bearer request message for each session (i.e., for each PDN connection) to the S-GW. The modify bearer request message may include a bearer identifier (e.g., an EPS bearer ID) and may include an address and a downlink (DL) TEID of the target LTE eNB 2. The S-GW may send a modify bearer response message to the control node in the NG core 5. In step 1112, the control node in the NG core 5 sends a path switching request confirmation message to the target LTE eNB 2.

[0216] The detailed process of switching from the NG system to the LTE system according to this embodiment is not limited to the above specific examples. For example, the names of the messages in the switching process are not limited to the names of the messages shown in the above examples. In the above examples of the switching process, the order of the messages can be changed, and some of the messages can be omitted. In addition, the messages may include one or more additional messages.

[0217] Fourth embodiment

[0218] This embodiment provides a method for switching UE 1 from a source NR NB to a target NR NB within an NG system. In the following description, switching within the NG system is referred to as intra-NR switching.

[0219] Fig.12 An example of the structure of a wireless communication network according to this embodiment is shown. Fig.12 In the example shown, the wireless communication network includes UE 1, NR NB 6 and NR NB 7, and NG Core 5. NR NB 6 can be, for example, a macro base station or a pico base station. Similarly, NR NB 7 can be a macro base station or a pico base station. Fig.12 In the example shown, NR NB 6 and NR NB 7 have coverage areas of similar size, and the cells of the two NR NB 6 and NR NB 7 partially overlap each other. Optionally, the wireless communication network according to the present embodiment may have a heterogeneous network (HetNet) structure. For example, NR NB 6 may be a macro base station and NRNB 7 may be a pico base station, and the macro cell of NR NB 6 may completely cover the pico cell of NR NB 7. Optionally, NRNB 6 may be a pico base station and NR NB 7 may be a macro base station.

[0220] NR NB 6 and NR NB 7 are connected to each other via a direct base station interface 1201. The direct base station interface 1201 is at least used to transmit signaling messages between NR NB 6 and NR NB 7. The direct base station interface 1201 may also be used to transmit user packets between NR NB 6 and NR NB 7. The control plane protocol structure and the user plane protocol structure of the direct base station interface 1201 may be the same as the control plane protocol structure and the user plane protocol structure of the X2 interface between LTE eNBs. The direct base station interface 1201 is, for example, called an NG X2 interface.

[0221] Several examples of intra-NR handover procedures are provided below. The examples described below are related to UE mobility that enables a connected UE 1 to be handed over from a source NR NB 6 to a target NR NB 7.

[0222] Fig.13 An example of an intra-NR handover procedure is shown. Fig.13 A case is shown where network slicing is applied to UE 1 in both the source cell / source NR NB 6 and the target cell / target NR NB 7. Fig.13 The process shown is similar to "X2 based handover" in LTE in that it involves transmitting handover signaling messages on the direct inter-base station interface 101 during the handover preparation phase (ie steps 1303 and 1304).

[0223] In step 1301, UE 1 is connected to source NR NB 6 and is in a connected state (i.e., RRC_Connected). The network slice is applied to UE 1 in the source cell / source NR NB 6. In step 1302, UE 1 receives a measurement configuration from NR NB 6, performs neighbor cell measurement according to the measurement configuration, and sends a measurement report to NR NB 6.

[0224] In step 1303, NR NB 6 determines intra-NR handover to the cell of NR NB 7. When determining the intra-NR handover, the source NR NB 6 sends an NR handover request message to the target NR NB 7 on the direct base station interface 1201.

[0225] The NR handover request message of step 1303 may include a list of packet flows (i.e., PDU flows) or bearers (i.e., radio access bearers) of UE 1 to be set in the target NR NB 7 (e.g., a list of PDU flows to be set). The list indicates flow information related to each packet flow. The flow information includes: a flow identifier (e.g., a PDU flow ID); an address of a transmitting node in the NG core 5 and an uplink (UL) session endpoint identifier (SEID); and flow QoS parameters.

[0226] The NR handover request message of step 1303 may include slice information. The slice information is related to one or more network slices to which UE 1 is connected (or is using) in the source cell / source NR NB6. The slice information enables the target NR NB 7 to identify one or more network slices to which UE 1 is connected. For example, the slice information may indicate an identifier (e.g., NSI-ID, NF ID, MDD) of each network slice to which UE 1 is connected. Additionally or optionally, the slice information may indicate a UE identifier assigned to UE 1 by a CP NF (or a control node corresponding to an MME) associated with each network slice. The UE identifier may be an identifier corresponding to an MME UE S1AP ID in LTE. In the case where UE 1 is connected to multiple network slices, multiple UE identifiers corresponding to each network slice may be assigned to UE 1.

[0227] In step 1304, the target NR NB 7 generates a UE context and allocates resources based on the NR handover request message. The target NR NB 7 can determine the admitted PDU flow based on the received flow information (e.g., a PDU flow list to be set). Based on the received slice information, the target NR NB 7 can identify one or more network slices to which the UE 1 is connected, and identify the CP NF (or control node corresponding to the MME) of each network slice.

[0228] The target NR NB 7 then generates a transparent container (e.g., RRC connection reconfiguration) to be sent to UE 1, and generates an NR handover request confirmation message (handover command to NR message) containing the transparent container. The target NR NB 7 sends the NR handover request confirmation message to the source NR NB 6 on the direct base station interface 1201. The transparent container includes, for example, the radio resource configuration information set by the target NR NB 7. The NR handover request confirmation message may also include the above-mentioned "Accepted PDU Flow List" information element (IE). The source LTE eNB 2 starts data forwarding for the flow (e.g., PDU flow) specified by the "Accepted PDU Flow List" IE.

[0229] In step 1305, the source NR NB 6 sends an NR RRC connection reconfiguration message to the UE 1. The RRC connection reconfiguration message includes a "MobilityControlInfoNR" IE. The "MobilityControlInfoNR" IE is generated by the target NR NB 7 and provides the configuration and information required to access the target cell / target NR NB 7 to the UE 1.

[0230] In step 1306, UE 1 moves from the source cell / source NR NB 6 to the target cell / target NR NB 7 in response to receiving the NR RRC connection reconfiguration message. In step 1307, after successfully synchronizing to the target cell, UE 1 sends an NR RRC connection reconfiguration complete message including a handover confirmation for the NR message to the target NR NB 7. The handover confirmation for the NR message or the NR RRC connection reconfiguration complete message may include network slice assistance information or slice configuration information.

[0231] In step 1308, when UE 1 successfully accesses the target NR NB 7, the target NR NB 7 sends an NR path switching request message to the NG core 5 to notify the NG core 5 that UE 1 has changed its cell and requests path switching. The NR path switching request message may include a list of bearers (i.e., E-RABs) or packet flows (i.e., PDU flows) of UE 1 that have been switched to the cell of the target NR NB 7. More specifically, the NR path switching request message may include the "List of E-RABs / Flows to be switched in downlink (DL)" IE. The NR path switching request message of step 1308 may include slice information. The slice information indicates one or more network slices that UE 1 wishes to connect to (or use) in the target cell / target NRNB 7.

[0232] In step 1309, the NG core 5 performs a flow modification process. For example, the control node in the NG core 5 may send a modify flow request message for each session (i.e., for each PDU session) to the transmission node in the NG core 5. The modify flow request message may include a flow identifier (e.g., PDU flow ID), and may also include the address of the target NR NB 7 and a downlink (DL) session endpoint identifier (SEID). The session endpoint identifier (SEID) may be, for example, a tunnel endpoint identifier (TEID). The transmission node in the NG core 5 may send a modify flow response message to the control node in the NG core 5.

[0233] In step 1310, the control node in the NG core 5 sends an NR path switch request confirmation message to the target NRNB 7. In the case where the NG core 5 changes the uplink termination point of the tunnel, the NR path switch request confirmation message may include the "E-RAB / stream list to be converted in uplink (UL)" IE. The "E-RAB / stream list to be converted in UL" IE indicates the new uplink transport layer address and new endpoint identifier for each bearer (i.e., E-RAB) or each stream (i.e., PDU stream). In the case where the NG system supports bearer-based transmission of user data, the control node in the NG core 5 may perform a bearer modification process instead of the session creation process of step 1310.

[0234] In response to receiving the NR path switch request in step 1308, the control node in the NG core 5 may determine to change the network slice for UE 1 or determine that network slicing is not allowed for UE 1. Therefore, the NR path switch request confirmation message of step 1310 may include a slice information IE indicating the changed network slice for UE 1. Optionally, the NR path switch request confirmation message of step 1310 may indicate that network slicing is not allowed for UE 1.

[0235] In step 1311, the target NR NB 3 may send an NR DL information transfer message carrying NAS information (e.g., slice information IE) received from the NG core 5 to UE 1.

[0236] Fig.14 An example of an intra-NR handover procedure is shown. Fig.14 The switching process shown provides Fig.13 Details of the handover process and modifications to the handover process are shown, and the structure and signaling in the NG Core 5 are explained in detail. Fig.14 The specific structure of the NG core 5 shown is similar to Figure 8 Specifically, the NG core 5 includes a common NF 51 , a NF 52 for slice A, a NF 53 for slice B, and an HSS 54 .

[0237] Step 1401 corresponds to Fig.13 Here, as an example, slice A and slice B have been selected for UE 1. Step 1402 corresponds to Fig.13 The method includes steps 1302 to 1307, and includes a switching preparation phase and a switching execution phase.

[0238] Fig.14 Case A (i.e., steps 1403 to 1406) and case B (i.e., steps 1407 to 1410) are shown. Either case A or case B is performed. In case A, the CP NF (e.g., session management function (SMF) or mobility management function (MMF)) in the common NF 51 triggers flow modification (or bearer modification) for all slices used by the UE 1. In contrast, in case B, the CP NF (e.g., SMF or MMF) of each slice triggers flow modification (or bearer modification) for the slice.

[0239] First, case A is described. Step 1403 corresponds to Fig.13 Step 1308. In step 1403, the target NR NB 7 sends an NR path switching request message to the common NF 51. As already explained, the NR path switching request message may include the "E-RAB / flow list to be switched in downlink (DL)" IE. The NR path switching request message may also include slice information. The slice information indicates one or more network slices that the UE 1 wants to connect to (or use) in the target cell / target NR NB 7.

[0240] Steps 1404 and 1405 correspond to Fig.13 In steps 1309. In steps 1404 and 1405, the CPNF within the common NF 51 triggers the NF 52 for slice A and the NF 53 for slice B to perform flow modification (or bearer modification).

[0241] Step 1406 corresponds to Fig.13 In step 1310. In step 1406, the public NF 51 sends a NR path switch request confirm message to the target NR NB 7. As already explained, the NR path switch request confirm message may contain the "E-RAB / Flow List to be switched in UL" IE.

[0242] Next, case B is described. Step 1407 corresponds to Fig.13Step 1308. In step 1407, NR NB 7 sends the UE path switching request message to each CP NF of one or more network slices that UE1 wants to connect to (or use) in the target cell / target NR NB 7 (i.e., the CP NF in NF 52 for slice A and the CP NF in NF 53 for slice B). The target NRNB 7 can determine (or select) one or more network slices to which the NR path switching request message will be sent based on the slice information contained in the NR switching request message received from the source NR NB 6 (step 1402 or 1303). Optionally, the target NR NB 7 can determine (or select) one or more network slices to which the NR path switching request message will be sent based on the network slice auxiliary information or slice information contained in the NR RRC connection reconfiguration completion message (or switching confirmation for NR message) received from UE 1.

[0243] Steps 1408 and 1409 correspond to Fig.13 In step 1309, slice A uses NF52 to perform flow modification (or bearer modification) in slice A. In step 1409, slice B uses NF53 to perform flow modification (or bearer modification) in slice B.

[0244] Step 1410 corresponds to Fig.13 In step 1310. In step 1410, the CP NF in NF 52 of slice A sends the NR path switching request confirmation message to the target NR NB 7, and the CP NF in NF 53 of slice B also sends the NR path switching request confirmation message to the target NR NB 7.

[0245] Fig.15 An example of an intra-NR handover procedure is shown. Fig.15 The following situation is shown: network slicing is not applied to UE 1 in the source cell / source NR NB 6, but network slicing is applied to UE 1 in the target cell / target NR NB 7.

[0246] In step 1501, UE 1 is connected to source NR NB 6 and is in a connected state (ie, RRC_Connected). No network slicing is applied to UE 1 in the source cell / source NR NB 6.

[0247] Steps 1502 to 1507 and Fig.13Steps 1302 to 1507 are basically the same. However, the NR handover request message of step 1503 does not need to include slice information. In contrast, the NR RRC connection reconfiguration complete message (or handover confirmation for NR message) of step 1507 may include network slice assistance information. The network slice assistance information may be NAS information or RRC information.

[0248] Steps 1508 to 1510 are the handover completion phase and are related to Fig.13 Steps 1308 to 1310 are basically the same. However, in step 1509, the NG core 5 further performs slice selection for UE 1. In order to assist the slice selection in the NG core 5, the NR path switch request message of step 1508 may include network slice assistance information sent from UE 1. The NR path switch request confirmation message of step 1510 may include slice information. The slice information relates to one or more network slices selected by the NG core 5 for UE 1.

[0249] Step 1511 corresponds to Fig.13 Step 1311. The NR DL information transmission message of step 1511 can carry the slice information sent from the NG core 5.

[0250] Fig.16 An example of an intra-NR handover procedure is shown. Fig.16 The switching process shown provides Fig.15 Details of the handover process and modifications to the handover process are shown, and the structure and signaling in the NG Core 5 are explained in detail. Fig.16 The specific structure of the NG core 5 shown is similar to Figure 8 The specific structure of the NG core 5 shown is the same.

[0251] Step 1601 corresponds to Fig.15 Step 1501 corresponds to step 1602. Fig.15 The handover execution step 1502 to 1507 of the present invention includes a handover preparation phase and a handover execution phase. Note that UE 1 may send the network slice assistance information to the target NR NB 7 during step 1602 or before step 1602. For example, UE 1 may send the network slice assistance information via an NR RRC connection reconfiguration complete message (or a handover confirmation for an NR message).

[0252] Step 1603 corresponds to Fig.13In step 1308. In step 1603, the target NR NB 7 sends an NR path switch request message to the common NF 51. As already explained, the NR path switch request message may include the "List of E-RABs / Flows to be switched in downlink (DL)" IE. In addition, the NR path switch request message may include network slice assistance information.

[0253] In step 1604, if necessary, the public NF 51 performs authentication of the UE 1. The authentication includes confirmation (slice authorization) of the slices allowed (or authorized) to the UE 1. In the slice authorization, the public NF 51 can decide / judge whether the UE 1 is allowed for each slice.

[0254] Fig.16 The following situation is shown: at least one network slice has been allowed for UE 1, or at least one network slice is applicable to the ongoing service performed by UE 1 or the service requested by UE 1. Therefore, in step 1605, the public NF51 performs slice selection. Fig.16 In the example shown, the public NF 51 selects slice A for UE 1. The slice selection in step 1605 may be performed for each ongoing service performed by UE 1 or for each service requested by UE 1 (e.g., for each EPS bearer / E-RAB or for each IP flow). The slice selection in step 1605 may be performed by an SSF located at a location separate from the public NF 51.

[0255] Step 1606 corresponds to Fig.15 Step 1509. The public NF 51 communicates with the NF 52 for slice A of the slice selected for UE 1 (slice A in this example) to perform flow modification (or bearer modification). By doing so, the public NF 51 and the NF 52 for slice A convert the uplink and downlink transmission points of the packet flow (i.e., PDU flow) or bearer of UE 1 from the public network slice (i.e., the public NF 51) to slice A (i.e., the NF 52 for slice A).

[0256] Step 1607 corresponds to Fig.15 Step 1510. The public NF 51 sends the NR path switch request confirm message to the target NR NB 7. The CP NF of the selected slice (i.e., NF 52 for slice A) can send the NR path switch request confirm message to the target NR NB 7 on behalf of the public NF 51. As already explained, the NR path switch request confirm message of step 1607 can contain the "E-RAB / Flow List to be converted in UL" IE.

[0257] The NR path switching request confirmation message of step 1607 may also include slice information. The slice information enables the target NR NB 7 to identify one or more network slices selected by the NG core 5 for UE 1. For example, the slice information may indicate an identifier (e.g., NSI-ID, NF ID, MDD) of each network slice. Additionally or optionally, the slice information may indicate a UE identifier assigned to UE 1 by a CP NF (or a control node corresponding to the MME) associated with each network slice. The UE identifier may be an identifier corresponding to the MME UE S1AP ID in LTE. In the case where UE 1 is connected to multiple network slices, multiple UE identifiers corresponding to each network slice may be assigned to UE 1.

[0258] Step 1608 corresponds to Fig.15 Step 1511. The NR DL information transfer message can carry all or part of the slice information sent from the NG core 5.

[0259] Fig.17 An example of an intra-NR handover procedure is shown. Fig.17 The following situation is shown: the network slice is applied to UE 1 in the source cell / source NR NB 6, while the network slice is not applied to UE 1 in the target cell / target NR NB 7.

[0260] In step 1701, Fig.13 The process in steps 1702 to 1711 is the same as step 1301, where the network slice is applied to UE 1 in the source cell / source NR NB 6. Fig.13 The processing of steps 1302 to 1311 is the same. However, in step 1709, the NG Core 5 determines that network slicing should not be applied to UE 1 in the target cell / target NR NB 7, and converts the uplink and downlink transmission points of the packet flow or bearer of UE 1 from slice A and slice B (i.e., NF 52 for slice A and NF 53 for slice B) to the common network slice (i.e., common NF 51). Therefore, the NR path switching request confirmation message of step 1710 may include information that explicitly or implicitly indicates that the network slice is not applied to UE 1. The NR DL information transmission message of step 1711 may also include information that explicitly or implicitly indicates that the network slice is not applied to UE 1.

[0261] Fig.18 An example of an intra-NR handover procedure is shown. Fig.18 The switching process shown provides Fig.17 Details of the handover process and modifications to the handover process are shown, and the structure and signaling in the NG Core 5 are explained in detail. Fig.18 The specific structure of the NG core 5 shown is similar to Figure 8 The specific structure of the NG core 5 shown is the same.

[0262] The processing in steps 1801 to 1803 is Fig.14 The processing of steps 1401 to 1403 is the same. In step 1804, if necessary, the public NF 51 authenticates UE 1. The authentication includes confirmation of the slices allowed (or authorized) to UE 1 (slice authorization). In slice authorization, the public NF 51 can decide / judge whether UE 1 is allowed for each slice. The public NF 51 determines that network slicing is not allowed for UE 1, or that no network slice can be applied to the ongoing service performed by UE 1 or the service requested by UE 1.

[0263] Steps 1805 and 1806 correspond to Fig.17 Step 1709. In steps 1805 and 1806, the CPNF within the public NF 51 triggers the NF 52 for slice A and the NF 53 for slice B to perform flow modification (or bearer modification), thereby converting the uplink and downlink transmission points of the packet flow or bearer of UE 1 from slice A and slice B (i.e., NF 52 for slice A and NF 53 for slice B) to the public network slice (i.e., public NF 51).

[0264] Steps 1807 and 1808 correspond to Fig.17 In step 1807, the public NF 51 sends a NR path switch request confirm message to the target NR NB 7. In step 1808, the target NR NB 7 sends a NR DL information transfer message to UE 1. The NR path switch request confirm message and the NR DL information transfer message may contain information that explicitly or implicitly indicates that the network slice is not applied to UE 1.

[0265] As can be understood from the above description, the intra-NR handover process described in this embodiment enables handover of UE 1 in a wireless communication network supporting network slicing. In particular, referring to Figures 15 to 18 The intra-NR handover procedure enables handover of UE 1 when network slicing is not applied to one of the source cell / source NR NB 6 and the target cell / target NR NB 7.

[0266] The following provides a structural example of UE 1, LTE eNB 2, NR NB 3, NR NB 6, NR NB 7 and core network nodes according to the above embodiment. Fig.191 is a block diagram showing a structural example of UE 1. LTE transceiver 1901 performs analog RF signal processing related to the PHY layer of LTE RAT to communicate with LTE eNB 2. The analog RF signal processing performed by LTE transceiver 1901 includes up-conversion, down-conversion and amplification. LTE transceiver 1901 is connected to antenna 1902 and baseband processor 1905. That is, LTE transceiver 1901 receives modulation symbol data (or OFDM symbol data) from baseband processor 1905, generates a transmit RF signal, and supplies the generated transmit RF signal to antenna 1902. In addition, LTE transceiver 1901 generates a baseband receive signal based on the receive RF signal received by antenna 1902, and supplies the generated baseband receive signal to baseband processor 1905.

[0267] The new radio (NR) transceiver 1903 performs analog RF signal processing related to the PHY layer of the NG RAT to communicate with the NR NB 3. The new 5G (NR) transceiver 1903 is connected to the antenna 1904 and the baseband processor 1905.

[0268] The baseband processor 1905 performs digital baseband signal processing (i.e., data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) generation / decomposition of transmission format (i.e., transmission frame), (d) channel coding / decoding, (e) modulation (i.e., symbol mapping) / demodulation, and (f) generation of OFDM symbol data (i.e., baseband OFDM signal) through inverse fast Fourier transform (IFFT). On the other hand, control plane processing includes communication management of layer 1 (e.g., transmission power control), layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and layer 3 (e.g., signaling related to attachment, mobility, and packet communication).

[0269] For example, in the case of LTE or Advanced LTE, the digital baseband signal processing performed by the baseband processor 1905 may include signal processing of a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a medium access control (MAC) layer, and a physical (PHY) layer. In addition, the control plane processing performed by the baseband processor 1905 may include processing of a non-access stratum (NAS) protocol, an RRC protocol, and a MAC CE.

[0270] The baseband processor 1905 may include a modem processor (e.g., a digital signal processor (DSP)) for performing digital baseband signal processing and a protocol stack processor (e.g., a central processing unit (CPU) or a microprocessor unit (MPU)) for performing control plane processing. In this case, the protocol stack processor for performing control plane processing may be integrated with the application processor 1906 described below.

[0271] The application processor 1906 may also be referred to as a CPU, an MPU, a microprocessor, or a processor core. The application processor 1906 may include a plurality of processors (processor cores). The application processor 1906 loads a system software program (operating system (OS)) and various application programs (e.g., a communication application for acquiring metering data or sensing data) from the memory 1908 or from other memory (not shown), and executes these programs, thereby providing various functions of the UE 1.

[0272] In some implementations, such as Fig.19 As shown by the dashed line (1907) in FIG. 1 , the baseband processor 1905 and the application processor 1906 may be integrated on a single chip. In other words, the baseband processor 1905 and the application processor 1906 may be implemented on a single system on chip (SoC) device 1907. The SoC device may be referred to as a system large scale integration (LSI) or a chipset.

[0273] The memory 1908 is a volatile memory, a non-volatile memory, or a combination thereof. The memory 1908 may include a plurality of memory devices that are physically independent of each other. The volatile memory is, for example, a static random access memory (SRAM), a dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, a mask read-only memory (MROM), an electrically erasable programmable ROM (EEPROM), a flash memory, a hard disk drive, or any combination thereof. The memory 1908 may include, for example, an external memory device that can be accessed by the baseband processor 1905, the application processor 1906, and the SoC 1907. The memory 1908 may include an internal memory device integrated in the baseband processor 1905, the application processor 1906, or the SoC 1907. In addition, the memory 1908 may include a memory in a universal integrated circuit card (UICC).

[0274] The memory 1908 may store one or more software modules (computer programs) 1909 including instructions and data for performing the processing described in the above embodiments using the UE 1. In some implementations, the baseband processor 1905 or the application processor 1906 may load the software module 1909 from the memory 1908 and execute the loaded software module, thereby performing the processing of the UE 1 described in the above embodiments.

[0275] Fig. 20 2 is a block diagram showing a structural example of the LTE eNB 2 according to the above-mentioned embodiment. Fig. 20 As shown, LTEeNB 2 includes an LTE transceiver 2001, a network interface 2003, a processor 2004, and a memory 2005. The LTE transceiver 2001 performs analog RF signal processing to communicate with UEs supporting LTE RAT including UE 1. The LTE transceiver 2001 may include a plurality of transceivers. The LTE transceiver 2001 is connected to an antenna 2002 and a processor 2004. The LTE transceiver 2001 receives modulation symbol data (or OFDM symbol data) from the processor 2004, generates a transmit RF signal, and supplies the generated transmit RF signal to the antenna 2002. In addition, the LTE transceiver 2001 generates a baseband receive signal based on the receive RF signal received by the antenna 2002, and supplies the signal to the processor 2004.

[0276] The network interface 2003 is used to communicate with network nodes (eg, control nodes and transmission nodes). The network interface 2003 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0277] The processor 2004 performs digital baseband signal processing (i.e., data plane processing) and control plane processing for wireless communication. For example, in the case of LTE or Advanced LTE, the digital baseband signal processing performed by the processor 2004 may include signal processing of the PDCP layer, the RLC layer, the MAC layer, and the PHY layer. In addition, the control plane processing performed by the processor 2004 may include processing of the S1 protocol, the RRC protocol, and the MAC CE.

[0278] The processor 2004 may include a plurality of processors. The processor 2004 may include, for example, a modem processor (eg, DSP) for performing digital baseband signal processing and a protocol stack processor (eg, CPU or MPU) for performing control plane processing.

[0279] The memory 2005 includes a combination of a volatile memory and a non-volatile memory. The volatile memory is, for example, an SRAM, a DRAM, or a combination thereof. The non-volatile memory is, for example, an MROM, a PROM, a flash memory, a hard disk drive, or a combination thereof. The memory 2005 may include a memory configured separately from the processor 2004. In this case, the processor 2004 may access the memory 2005 via the network interface 2003 or an I / O interface (not shown).

[0280] The memory 2005 may store one or more software modules (computer programs) 2006 including instructions and data for performing the processing described in the above embodiments using the LTE eNB 2. In some implementations, the processor 2004 may load one or more software modules 2006 from the memory 2005 and execute the loaded software modules, thereby performing the processing of the LTE eNB 2 described in the above embodiments.

[0281] Fig.21 NR NB 6 and NR NB 7 may have Fig.21 The structure shown. Fig.21 As shown, NR NB 3 includes a new radio (NR) transceiver 2101, a network interface 2103, a processor 2104, and a memory 2105. The NR transceiver 2101 performs analog RF signal processing to communicate with UEs supporting NG RAT including UE 1. The NR transceiver 2101 may include a plurality of transceivers. The NR transceiver 2101 is connected to an antenna 2102 and a processor 2104. The NR transceiver 2101 receives modulation symbol data from the processor 2104, generates a transmit RF signal, and supplies the generated transmit RF signal to the antenna 2102. In addition, the NR transceiver 2101 generates a baseband receive signal based on the receive RF signal received by the antenna 2102, and supplies the signal to the processor 2104.

[0282] The network interface 2103 is used to communicate with network nodes, such as a control node and a transmission node in the NG core 5. The network interface 2103 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0283] The processor 2104 performs digital baseband signal processing (i.e., data plane processing) and control plane processing for wireless communication. The processor 2104 may include multiple processors. The processor 2104 may include, for example, a modem processor (e.g., DSP) for performing digital baseband signal processing and a protocol stack processor (e.g., CPU or MPU) for performing control plane processing.

[0284] The memory 2105 includes a combination of a volatile memory and a non-volatile memory. The volatile memory is, for example, an SRAM, a DRAM, or a combination thereof. The non-volatile memory is, for example, an MROM, a PROM, a flash memory, a hard disk drive, or a combination thereof. The memory 2105 may include a memory configured separately from the processor 2104. In this case, the processor 2104 may access the memory 2105 via the network interface 2103 or an I / O interface (not shown).

[0285] The memory 2105 may store one or more software modules (computer programs) 2106 including instructions and data for performing the processing using the NR NB 3 described in the above embodiments. In some implementations, the processor 2104 may load one or more software modules 2106 from the memory 2105 and execute the loaded software modules, thereby performing the processing of the NR NB 3 described in the above embodiments.

[0286] Fig. 22 2 is a block diagram showing a structural example of a core network node 2200 according to the above-described embodiment. The core network node 2200 is, for example, a control node (for example, a public NF 51) in the NG core 5. Fig. 22 As shown, the core network node 2200 includes a network interface 2201, a processor 2202 and a memory 2203. The network interface 2201 is used to communicate with a network node (e.g., a RAN node or other core network node). The network interface 2201 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0287] The processor 2202 may be, for example, a microprocessor, an MPU, or a CPU. The processor 2202 may include a plurality of processors.

[0288] The memory 2203 includes a combination of a volatile memory and a non-volatile memory. The volatile memory is, for example, an SRAM, a DRAM, or a combination thereof. The non-volatile memory is, for example, an MROM, a PROM, a flash memory, a hard disk drive, or a combination thereof. The memory 2203 may include a memory configured separately from the processor 2202. In this case, the processor 2202 may access the memory 2203 via the network interface 2201 or an I / O interface (not shown).

[0289] The memory 2203 may store one or more software modules (computer programs) 2204 including instructions and data for performing the processing of the core network node (e.g., the control node in the NG core 5) described in the above embodiments. In some implementations, the processor 2202 may load one or more software modules 2204 from the memory 2203 and execute the loaded software modules, thereby performing the processing of the core network node described in the above embodiments.

[0290] As mentioned above Figures 19 to 22As described above, the processors included in the UE 1, LTE eNB 2, NR NB 3 and core network nodes in the above embodiments execute one or more programs including an instruction set for causing the computer to perform the algorithm described above with reference to the accompanying drawings. Various types of non-transitory computer-readable media can be used to store these programs and thus supply these programs to the computer. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include: magnetic recording media (such as floppy disks, magnetic tapes, and hard disk drives); magneto-optical recording media (such as magneto-optical disks); compact disk read-only memory (CD-ROM); CD-R; CD-R / W; and semiconductor memory (such as mask ROM, programmable ROM (PROM), erasable PROM (EPROM), flash ROM, and random access memory (RAM)). These programs can be supplied to the computer by using various types of temporary computer-readable media. Examples of temporary computer-readable media include electrical signals, optical signals, and electromagnetic waves. Temporary computer-readable media can be used to supply the program to the computer via a wired communication line (e.g., wires and optical fibers) or a wireless communication line.

[0291] Fifth embodiment

[0292] This embodiment provides specific examples of the RRC messages described in the above embodiments, the control messages between the RAN and the core network (ie, NG2 messages), and the control messages between the source base station and the target base station (ie, X3 messages).

[0293] Fig.23A and 23B An example of the format of a mobility command message from EUTRA is shown. In the case of a handover from an LTE system to a NG system, the MobilityFromEUTRACommand message includes a purpose set to "handover" and a targetRAT-Type set to "ngutra" corresponding to the NG RAN. In addition, the MobilityFromEUTRACommand message includes a targetRAT-MessageContainer. The targetRAT-MessageContainer contains the RRCConnectionReconfigurationNR message generated by the target NR NB 3. In addition, in the case where the targetRAT-Type is "OTHERRAN" (i.e., "utra", "geran" or "ngutra"), the MobilityFromEUTRACommand message includes nas-SecurityParamFromEUTRA.

[0294] Fig.24 Shown in Figure 2A Step 202 and Figure 3A An example of the format of the X3AP:NR handover request message sent from the source LTE eNB 2 to the target NR NB 3 on the direct inter-base station interface 101 (X3 interface) in step 302 of . The NR handover request message includes an identifier (i.e., a globally unique CNF ID (GUCNFI)) of the control node (common NF (CNF)) in the NG Core 5. The NR handover request message also includes UE context information.

[0295] Fig.25 An example of the format of UE context information is shown. Fig.25 In the example shown, the UE context information includes a list of NE-RABs to be set up. The list of NE-RABs to be set up indicates a list of radio access bearers (NE-RABs) that should be set up in the target NR NB 3. In the case where the NG system including the NR NB 3 and the NG Core 5 is configured to support bearer-based transport using bearers for each QoS level and for each PDU session, the NE-RAB list may be used. Fig.25 The format shown.

[0296] Fig.25 The UE context information shown also includes an RRC context. The RRC context includes an RRC handover preparation information message. The target NR NB 3 uses the RRC handover preparation information message to make settings related to resources and security to communicate with the UE 1 in the NG system.

[0297] also, Fig.25 The UE context information shown may include auxiliary information of the network slice (auxiliary data of the network slice). The source LTE eNB 2 may incorporate the auxiliary data of the network slice received from the UE 1 or the NG core 5 into the UE context information.

[0298] Fig.26 Shown in Figure 2A An example of the format of an X3AP:NR Handover Request Ack message sent from the target NR NB 3 to the source LTE eNB over the direct inter-base station interface 101 (X3 interface) in step 203 of FIG. 10A . The NR Handover Command message includes a target-to-source transparent container. The target-to-source transparent container includes radio resource configuration information (e.g., radio parameters) generated by the target NR NB 3. The target-to-source transparent container may include an RRC container containing the RRC NG-UTRA Handover Command message. In addition, Fig.26In the example shown, the NR handover request confirmation message includes an accepted NE-RAB list. The accepted NE-RAB list indicates a list of radio access bearers (NE-RABs) for which resources are prepared in the target cell.

[0299] Fig. 27 Shown in Figure 3A FIG. 2 is an example of the format of the X3AP: NR Handover Request Confirm message sent from the target NR NB 3 to the source LTE eNB on the direct inter-base station interface 101 (X3 interface) in step 305 of FIG. 2 . Fig. 27 The format shown is the same as Fig.26 The format shown differs in that it includes core network context information (NG Core Context). The NG Core Context may be transparently sent to the UE 1 via the source LTE eNB 2. Additionally or alternatively, part or all of the NG Core Context may be contained in a target-to-source transparent container. Fig.28 An example of the format of the NG Core context is shown. As described in the first embodiment, the NG Core information includes, for example, slice information and stream information (or PDU session information).

[0300] Fig.29 An example of the format of slice information is shown. As described in detail in the first embodiment, the slice information includes an identifier of the network slice determined (or selected) for UE 1 (i.e., a network slice instance ID) and an identifier of a network function or node associated with the network slice (i.e., a network function ID). The slice information may include type information of the network slice (i.e., a multidimensional descriptor). In addition, the slice information may include a mobility level or a session level or both.

[0301] Fig.30 An example of the format of the flow information is shown. As described in detail above in the first embodiment, the flow information includes information (e.g., a PDU session information list) related to at least one session (i.e., a PDU session) established in the NG system to transmit at least one packet flow (i.e., a PDU flow) of the UE 1. The flow information includes a session identifier (e.g., a PDU session ID), and also includes an address (transport layer address) of a transmission node in the NG core 5 and an uplink (UL) session endpoint ID (SIED).

[0302] Fig.31 An example of the format of a session endpoint ID is shown. As described in detail in the first embodiment, the session endpoint ID may be a GTP-TEID, a GRE-TEID, or an identifier of a network function or node (NF ID).

[0303] Other embodiments

[0304] Each of the above embodiments may be used alone, or two or more of these embodiments may be appropriately combined with each other.

[0305] The above embodiment has been described based on the structural example of a network in which both the LTE eNB 2 and the NR NB 3 are connected to the NG core 5. Optionally, the LTE eNB 2 may be connected to an EPC that is enhanced to interoperate with the NG system (i.e., an enhanced EPC (eEPC)). The (e)MME in the eEPC may be connected to a control node (i.e., a CPF node) in the NG core 5 via a control plane interface. In addition, one or more nodes in the eEPC may be connected to one or more data nodes (i.e., UPF nodes) in the NG core 5 via a user plane interface.

[0306] The E-URAN and NG RAN described in the above embodiments can be implemented based on the concept of cloud radio access network (C-RAN). C-RAN is also called centralized RAN. In this case, the processing and operations performed by the LTE eNB 2 and NR NB 3 described in the above embodiments can be provided by a digital unit (DU) included in the C-RAN architecture, or by a combination of a DU and a radio unit (RU). DU is also called a baseband unit (BBU) or a central unit (CU). RU is also called a remote radio head (RRH), a remote radio equipment (RRE) or a distributed unit (DU). DU and RU can provide these functions by dividing the functions of the AS layer provided in the entire RAN into functions provided by the DU and functions provided by the RU. For example, DU and RU can be provided by the following structure: a part of the AS layer (e.g., layer 2 / layer 3 or its sublayer, or a part of the function of the layer) is arranged in the DU, and the remaining layers (or the rest of the layers) are arranged in the RU. That is, the processing and operations performed by the LTE eNB 2 and NR NB 3 described in the above embodiments can be provided by one or more wireless stations (or RAN nodes).

[0307] NR NB 3 may be configured to dynamically change the allocation of the AS layer or its functions to the DU and RU. In other words, NR NB 3 may be configured to dynamically change the split point of the AS layer or its functions between the DU and the RU. For example, NR NB 3 may be configured to dynamically select one of a plurality of different functional split options. In this case, in the HO process from LTE to NR in the above-mentioned embodiment, the NG core 5 may determine the allocation of the AS layer or its functions to the DU and RU of NR NB 3 in response to receiving the information required for handover preparation or the NR path switching request message. Alternatively, NR NB 3 may determine the allocation of the AS layer or its functions to the DU and RU of NR NB 3. The NG core 5 or NR NB 3 may select a functional split option to be applied to NR NB 3 from a plurality of predetermined functional split options.

[0308] In the example, the functional split option to be applied to NR NB 3 can be determined (or selected) based on the E-RAB QoS information IE (e.g., QCI or ARP) or flow information included in the handover preparation required message or the NR path switch request message. Additionally or optionally, the functional split option to be applied to NR NB 3 can be determined based on the slice created by the NG core 5 or NR NB 3 or information related to the slice (slice information). Additionally or optionally, the functional split option to be applied to NR NB 3 can be determined based on the network slice assistance information included in the NAS information sent from UE 1.

[0309] In addition, in the above embodiment, the UE identifier may be included in the message transmitted between nodes. The UE identifier is used to identify the UE 1 to be handed over during the handover process.

[0310] More specifically, the UE identifier may be a UE identifier used on an interface (e.g., Sn interface or NG2 interface, n is an integer) between the NR NB 3 and a control node corresponding to the MME and included in the NG Core 5. The UE identifier may be represented as an NR NB UE SnAP ID (NR NB UE Sn Application Protocol Identifier) ​​or an NR NB UE NG2AP ID.

[0311] Alternatively, the UE identifier may be a UE identifier used on an interface (e.g., Xn interface, n is an integer) between the NR NB 3 and the LTE eNB 2. The UE identifier may be represented as NR NB UE XnAP ID.

[0312] Alternatively, the UE identifier may be a UE identifier used on an interface (eg, Sm interface, m is an integer) between an MME in EPC 4 and a control node corresponding to the MME and included in NG Core 5. The UE identifier may be represented as eMME UE SmAP ID.

[0313] Alternatively, the UE identifier may be a UE identifier that is used on an interface (e.g., S1 interface, where l is an integer) between the LTE eNB 2 and a control node corresponding to the MME and included in the NG Core 5 and is allocated by the control node. The UE identifier may be represented as an eMME UE S1AP ID.

[0314] Furthermore, these UE identifiers may be transmitted between nodes during a handover process. Note that Sn, NG2, Sm, S1, and Xn used to identify the respective interfaces are merely examples and may be represented by different symbols.

[0315] In addition, the above-described embodiments are merely examples of application of the technical ideas obtained by the present inventors. These technical ideas are not limited to the above-described embodiments, and various modifications can be made to these technical ideas.

[0316] For example, all or part of the embodiments disclosed above may be described as, but not limited to, the following supplementary descriptions.

[0317] (Supplementary Note 1)

[0318] A target radio access network node, namely a target RAN node, is associated with a second network, the target RAN node comprising:

[0319] at least one memory; and

[0320] at least one processor connected to the at least one memory and configured to:

[0321] receiving a handover request message from a source RAN node in a first network over a direct interface, the handover request message requesting handover of a wireless terminal from the first network to the second network;

[0322] In response to receiving the handover request message, receiving at least one of slice information and flow information from a core network; and

[0323] controlling communication of the wireless terminal based on at least one of the slice information and the stream information,

[0324] The slice information is related to a network slice in the second network to which the wireless terminal is to be connected, and

[0325] The flow information is related to at least one session to be established in the second network serving as a bearerless network for transmitting at least one packet flow of the wireless terminal.

[0326] (Supplementary Note 2)

[0327] A target RAN node according to Supplementary Note 1, wherein the slice information includes: (a) identification information of the network slice selected for the wireless terminal; (b) type information of the network slice selected for the wireless terminal; or (c) identification information of a network node or network function associated with the network slice selected for the wireless terminal; or any combination of such information.

[0328] (Supplementary Note 3)

[0329] The target RAN node according to Supplementary Note 1 or 2, wherein the slice information includes at least one of the mobility level and session level supported by the network slice selected for the wireless terminal.

[0330] (Supplementary Note 4)

[0331] The target RAN node according to any one of Supplementary Notes 1 to 3, wherein the flow information includes a flow identifier and a flow QoS parameter for each packet flow of the wireless terminal.

[0332] (Supplementary Note 5)

[0333] A target RAN node according to any one of Supplementary Notes 1 to 4, wherein the at least one processor is configured to receive at least one of the slice information and the flow information from the core network during a switching completion phase after the wireless terminal is connected to the target RAN node.

[0334] (Supplementary Note 6)

[0335] The target RAN node according to Supplementary Note 5, wherein:

[0336] The handover request message includes security parameters derived by the source RAN node, and

[0337] The at least one processor is configured to derive an access stratum security key (AS security key) from the security parameter.

[0338] (Supplementary Note 7)

[0339] The target RAN node according to Supplementary Note 5 or 6, wherein:

[0340] The at least one processor is configured to send the path switch request message to the core network during the handover completion phase, and

[0341] The path switching request message triggers the core network to select or create a network slice for the wireless terminal.

[0342] (Supplementary Note 8)

[0343] The target RAN node according to Supplementary Note 5 or 6, wherein:

[0344] The at least one processor is configured to send a path switching request message to the core network during the handover completion phase, and

[0345] The path switch request message triggers the core network to create a bearerless session for the wireless terminal.

[0346] (Supplementary Note 9)

[0347] The target RAN node according to any one of Supplementary Notes 5 to 8, wherein the at least one processor is configured to send at least one of the slice information and the flow information to the wireless terminal.

[0348] (Supplementary Note 10)

[0349] A target RAN node according to any one of Supplementary Notes 1 to 4, wherein the at least one processor is configured to receive at least one of the slice information and the flow information from the core network during a switching preparation phase before the source RAN node issues a switching indication to the wireless terminal.

[0350] (Supplementary Note 11)

[0351] The target RAN node according to Supplementary Note 10, wherein the at least one processor is configured to determine whether to accept the bearer or flow of the wireless terminal for each bearer or for each flow based on the slice information.

[0352] (Supplementary Note 12)

[0353] The target RAN node according to Supplementary Note 10 or 11, wherein the at least one processor is configured to determine whether each network slice can be accepted based on the slice information.

[0354] (Supplementary Note 13)

[0355] A target RAN node according to any one of Supplementary Notes 10 to 12, wherein the at least one processor is further configured to receive non-access stratum security configuration information, i.e., NAS security configuration information and security parameters from the core network during the switching preparation phase, and the security parameters are used by the target RAN node to derive an access stratum security key, i.e., AS security key.

[0356] (Supplementary Note 14)

[0357] The target RAN node according to any one of Supplementary Notes 10 to 13, wherein:

[0358] The at least one processor is configured to send a handover request confirmation message including a transparent container to the source RAN node over the direct interface,

[0359] The transparent container includes at least one of the following: predetermined parameters included in at least one of the slice information and the flow information; and wireless resource configuration information generated based on at least one of the slice information and the flow information, and the transparent container is to be forwarded by the source RAN node to the wireless terminal.

[0360] (Supplementary Note 15)

[0361] The target RAN node according to any one of Supplementary Notes 10 to 14, wherein:

[0362] The at least one processor is configured to send a request message requesting at least one of the slice information and the flow information to the core network during the handover preparation phase,

[0363] The request message triggers the core network to select or create a network slice for the wireless terminal.

[0364] (Supplementary Note 16)

[0365] The target RAN node according to any one of Supplementary Notes 10 to 14, wherein:

[0366] The at least one processor is configured to send a request message requesting at least one of the slice information and the flow information to the core network during the handover preparation phase,

[0367] The request message triggers the core network to create a bearerless session for the wireless terminal.

[0368] (Supplementary Note 17)

[0369] A source radio access network node, namely a source RAN node, is associated with a first network, the source RAN node comprising:

[0370] at least one memory; and

[0371] at least one processor connected to the at least one memory and configured to:

[0372] Determining a handover of the wireless terminal from the first network to the second network;

[0373] In response to the determination of the handover, sending a handover request message to a target RAN node in the second network on a direct interface, the handover request message requesting handover of the wireless terminal to the second network;

[0374] receiving a handover request confirmation message including a transparent container from the target RAN node over the direct interface; and

[0375] sending a mobility command message including the transparent container and indicating handover to the second network to the wireless terminal,

[0376] The transparent container includes wireless resource configuration information required by the wireless terminal to establish a wireless connection associated with the second network, and

[0377] The wireless resource configuration information includes at least one of the following: (a) first wireless resource configuration information generated based on slice information, the slice information being related to a network slice in the second network to which the wireless terminal is to be connected; and (b) second wireless resource configuration information generated based on flow information, the flow information being related to at least one session to be established in the second network used as an unloaded network in order to transmit at least one packet flow of the wireless terminal.

[0378] (Supplementary Note 18)

[0379] The source RAN node according to Supplementary Note 17, wherein:

[0380] The at least one processor is configured to derive second security parameters to be used in the second network from first security parameters used in the first network and to incorporate the second security parameters into the handover request message,

[0381] The second security parameter is used by the target RAN node to derive an access stratum security key, namely, an AS security key, for the second network.

[0382] (Supplementary Note 19)

[0383] A method in a target radio access network node, i.e. a target RAN node, wherein the target RAN node is associated with a second network, the method comprising:

[0384] receiving a handover request message from a source RAN node in a first network over a direct interface, the handover request message requesting handover of a wireless terminal from the first network to the second network;

[0385] In response to receiving the handover request message, receiving at least one of slice information and flow information from a core network; and

[0386] controlling communication of the wireless terminal based on at least one of the slice information and the stream information,

[0387] The slice information is related to a network slice in the second network to which the wireless terminal is to be connected, and

[0388] The flow information is related to at least one session to be established in the second network serving as a bearerless network for transmitting at least one packet flow of the wireless terminal.

[0389] (Supplementary Note 20)

[0390] A method in a source radio access network node, i.e., a source RAN node, the source RAN node being associated with a first network, the method comprising:

[0391] Determining a handover of the wireless terminal from the first network to the second network;

[0392] In response to the determination of the handover, sending a handover request message to a target RAN node in the second network on a direct interface, the handover request message requesting handover of the wireless terminal to the second network;

[0393] receiving a handover request confirmation message including a transparent container from the target RAN node over the direct interface; and

[0394] sending a mobility command message including the transparent container and indicating handover to the second network to the wireless terminal,

[0395] The transparent container includes wireless resource configuration information required by the wireless terminal to establish a wireless connection associated with the second network, and

[0396] The wireless resource configuration information includes at least one of the following: (a) first wireless resource configuration information generated based on slice information, the slice information being related to a network slice in the second network to which the wireless terminal is to be connected; and (b) second wireless resource configuration information generated based on flow information, the flow information being related to at least one session to be established in the second network used as an unloaded network in order to transmit at least one packet flow of the wireless terminal.

[0397] (Supplementary Note 21)

[0398] A non-transitory computer-readable medium storing a program for causing a computer to perform a method in a target radio access network node, i.e., a target RAN node, the target RAN node being associated with a second network, wherein the method comprises:

[0399] receiving a handover request message from a source RAN node in a first network over a direct interface, the handover request message requesting handover of a wireless terminal from the first network to the second network;

[0400] In response to receiving the handover request message, receiving at least one of slice information and flow information from a core network; and

[0401] controlling communication of the wireless terminal based on at least one of the slice information and the stream information,

[0402] The slice information is related to a network slice in the second network to which the wireless terminal is to be connected, and

[0403] The flow information is related to at least one session to be established in the second network serving as a bearerless network for transmitting at least one packet flow of the wireless terminal.

[0404] (Supplementary Note 22)

[0405] A non-transitory computer-readable medium storing a program for causing a computer to perform a method in a source radio access network node, i.e., a source RAN node, the source RAN node being associated with a first network, wherein the method comprises:

[0406] Determining a handover of the wireless terminal from the first network to the second network;

[0407] In response to the determination of the handover, sending a handover request message to a target RAN node in the second network on a direct interface, the handover request message requesting handover of the wireless terminal to the second network;

[0408] receiving a handover request confirmation message including a transparent container from the target RAN node over the direct interface; and

[0409] sending a mobility command message including the transparent container and indicating handover to the second network to the wireless terminal,

[0410] The transparent container includes wireless resource configuration information required by the wireless terminal to establish a wireless connection associated with the second network, and

[0411] The wireless resource configuration information includes at least one of the following: (a) first wireless resource configuration information generated based on slice information, the slice information being related to a network slice in the second network to which the wireless terminal is to be connected; and (b) second wireless resource configuration information generated based on flow information, the flow information being related to at least one session to be established in the second network used as an unloaded network in order to transmit at least one packet flow of the wireless terminal.

[0412] (Supplementary Note 23)

[0413] A wireless terminal, comprising:

[0414] at least one memory; and

[0415] At least one processor is connected to the at least one memory and is configured to receive a switching-related message from a radio access network node, i.e., a RAN node, of the first network during switching from a first network to which the wireless terminal is connected to to a second network, wherein the switching-related message includes at least one of the following: slice information related to network slices in the second network; and wireless resource configuration information based on the network slices in the second network.

[0416] (Supplementary Note 24)

[0417] The wireless terminal according to Supplementary Note 23, wherein the at least one processor is configured to:

[0418] receiving, from the RAN node, a mobility command message indicating a handover from the first network to the second network, the mobility command message including radio resource configuration information generated by a target RAN node associated with the second network, the radio resource configuration information being required for the wireless terminal to establish a radio connection associated with a network slice included in the second network to which the wireless terminal is to be connected; and

[0419] The radio connection is established with the target RAN node associated with the second network by using the radio resource configuration information.

[0420] (Supplementary Note 25)

[0421] A wireless terminal according to Supplementary Note 23 or 24, wherein the switching-related message also includes flow information and at least one of wireless resource configuration information derived from the flow information, and the flow information is related to at least one session to be established in the second network in order to transmit at least one packet flow of the wireless terminal.

[0422] (Supplementary Note 26)

[0423] A core network node, comprising:

[0424] at least one memory; and

[0425] At least one processor is connected to the at least one memory and is configured to send slice information related to a network slice included in the second network to which the wireless terminal is to be connected to to a target radio access network node, i.e., a target RAN node, associated with the second network during switching of the wireless terminal from a first network to a second network.

[0426] (Supplementary Note 27)

[0427] The core network node according to Supplementary Note 26, wherein the at least one processor is further configured to send flow information to the target RAN node during switching of the wireless terminal from the first network to the second network, wherein the flow information is related to at least one session to be established in the second network for transmitting at least one packet flow of the wireless terminal.

[0428] (Supplementary Note 28)

[0429] According to the core network node described in Supplementary Note 26 or 27, the at least one processor is configured to send the slice information to the target RAN node during the switching preparation phase before the source RAN node issues a switching indication to the wireless terminal.

[0430] (Supplementary Note 29)

[0431] According to the core network node described in Supplementary Note 26 or 27, the at least one processor is configured to send the slice information to the target RAN node during the switching completion phase after the wireless terminal is connected to the target RAN node.

[0432] This application is based upon and claims the benefit of priority from Japanese patent application No. 2016-158282, filed on August 10, 2016, the entire contents of which are incorporated herein by reference.

[0433] Description of Reference Numerals

[0434] 1 User Equipment (UE)

[0435] 2 LTE eNodeB (eNB)

[0436] 3 New Radio (NR) Node B (NB)

[0437] 5 NextGen (NG) Core

[0438] 6 New Radio (NR) Node B (NB)

[0439] 7 New Radio (NR) Node B (NB)

[0440] 1905 Baseband Processor

[0441] 1906 Application Processor

[0442] 1908 Memory

[0443] 2004 Processor

[0444] 2005 Memory

[0445] 2104 Processor

[0446] 2105 Memory

[0447] 2202 Processor

[0448] 2203 Memory

Claims

1. A target radio access network node, i.e., a target RAN node, configured to be connected to a fifth generation core network, i.e., a 5G core network, wherein the target RAN node comprises: at least one memory; as well as at least one processor connected to the at least one memory and configured to: receiving a handover request message from a source RAN node connected to the 5G core network on a direct interface, the handover request message requesting an intra-NR handover of a wireless terminal from the source RAN node to the target RAN node; upon receiving the handover request message, creating radio resource configuration information to be used by the wireless terminal to communicate with the target RAN node after the intra-NR handover; as well as sending a handover request confirmation message including a transparent container containing the radio resource configuration information to the source RAN node, so as to send the radio resource configuration information to the wireless terminal via the source RAN node, wherein: The handover request message includes slice information and a list of packet flows of the wireless terminal to be set in the target RAN node, the list of packet flows including flow information related to each packet flow, The slice information is related to at least one network slice allocated to the 5G core network to which the wireless terminal is connected, and The flow information is related to at least one packet flow of the PDU session established in the 5G core network, and includes a flow identifier and a flow service quality parameter, i.e., a flow QoS parameter.

2. The target RAN node according to claim 1, wherein: The at least one processor is configured to control the wireless terminal after switching within the NR according to the slice information and the stream information.

3. A source radio access network node, i.e., a source RAN node, configured to be connected to a fifth generation core network, i.e., a 5G core network, the source RAN node comprising: at least one memory; as well as at least one processor connected to the at least one memory and configured to: Sending a handover request message to a target RAN node connected to the 5G core network over a direct interface, the handover request message requesting an intra-NR handover of the wireless terminal from the source RAN node to the target RAN node; receiving, from the target RAN node on the direct interface, a handover request confirmation message including a transparent container, the transparent container containing radio resource configuration information used by the wireless terminal to communicate with the target RAN node after the intra-NR handover; as well as The transparent container is sent to the wireless terminal, wherein: The handover request message includes slice information and a list of packet flows of the wireless terminal to be set in the target RAN node, the list of packet flows including flow information related to each packet flow, The slice information is related to at least one network slice allocated to the 5G core network to which the wireless terminal is connected, and The flow information is related to at least one packet flow of the PDU session established in the 5G core network, and includes a flow identifier and a flow service quality parameter, i.e., a flow QoS parameter.

4. A method performed by a target radio access network node, i.e. a target RAN node, wherein the target RAN node is configured to be connected to a fifth generation core network, i.e. a 5G core network, the method comprising: receiving a handover request message from a source RAN node connected to the 5G core network on a direct interface, the handover request message requesting an intra-NR handover of a wireless terminal from the source RAN node to the target RAN node; upon receiving the handover request message, creating radio resource configuration information to be used by the wireless terminal to communicate with the target RAN node after the intra-NR handover; as well as sending a handover request confirmation message including a transparent container containing the radio resource configuration information to the source RAN node, so as to send the radio resource configuration information to the wireless terminal via the source RAN node, wherein: The handover request message includes slice information and a list of packet flows of the wireless terminal to be set in the target RAN node, the list of packet flows including flow information related to each packet flow, The slice information is related to at least one network slice allocated to the 5G core network to which the wireless terminal is connected, and The flow information is related to at least one packet flow of the PDU session established in the 5G core network, and includes a flow identifier and a flow service quality parameter, i.e., a flow QoS parameter.

5. The method according to claim 4 further includes controlling the wireless terminal after switching within the NR according to the slice information and the stream information.

6. A method performed by a source radio access network node, i.e., a source RAN node, wherein the source RAN node is configured to be connected to a fifth generation core network, i.e., a 5G core network, the method comprising: Sending a handover request message to a target RAN node connected to the 5G core network over a direct interface, the handover request message requesting an intra-NR handover of the wireless terminal from the source RAN node to the target RAN node; receiving, from the target RAN node on the direct interface, a handover request confirmation message including a transparent container, the transparent container containing radio resource configuration information used by the wireless terminal to communicate with the target RAN node after the intra-NR handover; as well as The transparent container is sent to the wireless terminal, wherein: The handover request message includes slice information and a list of packet flows of the wireless terminal to be set in the target RAN node, the list of packet flows including flow information related to each packet flow, The slice information is related to at least one network slice allocated to the 5G core network to which the wireless terminal is connected, and The flow information is related to at least one packet flow of the PDU session established in the 5G core network, and includes a flow identifier and a flow service quality parameter, i.e., a flow QoS parameter.

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