Communication method, user equipment, and network node

Abstract

This communication method used in a mobile communication system includes: a step in which a user device performs, together with a network node, wireless communication using at least one network slice; and a step in which the user device transmits, to the network node, slice-related information used in order to perform mobility control of the user device. The slice-related information includes at least one of first information indicating the likelihood of usage of each network slice, second information indicating the degree of priority of each network slice, and third information indicating a traffic pattern of each network slice.

Description

COMMUNICATION METHOD, USER EQUIPMENT, AND NETWORK NODE

[0001] The present disclosure relates to a communication method, a user equipment, and a network node for use in a mobile communication system.

[0002] 3GPP (Third Generation Partnership Project) (registered trademark; the same applies hereinafter), a standardization project for mobile communication systems, is considering applying artificial intelligence or machine learning (also referred to as "AI (Artificial Intelligence) / ML (Machine Learning)") technology to the air interface of mobile communication systems.

[0003] 3GPP Technical Report: TR 38.843 V0.1.0 (2023-05), “Study on Artificial Intelligence (AI) / Machine Learning (ML) for NR air interface (Release 18)”

[0004] A communication method according to a first aspect is a method used in a mobile communication system. The communication method includes a step in which a user equipment performs wireless communication with a network node using at least one network slice, and a step in which the user equipment transmits slice-related information used for performing mobility control of the user equipment to the network node. The slice-related information includes at least one of first information indicating a usage probability of each network slice, second information indicating a priority of each network slice, and third information indicating a traffic pattern of each network slice.

[0005] A user device according to a second aspect is a device used in a mobile communication system. The user device includes: a control unit that performs wireless communication with a network node using at least one network slice; and a transmission unit that transmits slice-related information used to perform mobility control of the user device to the network node. The slice-related information includes at least one of first information indicating a usage probability of each network slice, second information indicating a priority of each network slice, and third information indicating a traffic pattern of each network slice.

[0006] A network node according to a third aspect is a node used in a mobile communication system. The network node includes a control unit that performs wireless communication with a user device using at least one network slice, and a receiving unit that receives slice-related information from the user device to be used for mobility control of the user device. The slice-related information includes at least one of first information indicating a usage probability of each network slice, second information indicating a priority of each network slice, and third information indicating a traffic pattern of each network slice.

[0007] A network node according to a fourth aspect is a node used in a mobile communication system. The network node includes a communication unit that transmits slice load information indicating a load status of each network slice to another network node. The slice load information includes, for each network slice, at least one of information on the number of user equipments in a radio resource control (RRC) connected state, information on the number of user equipments that are in an RRC connected state and are active, and information on a communication load per user equipment.

[0008] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. FIG. 2 is a diagram illustrating a configuration of a UE (user equipment) according to an embodiment. FIG. 3 is a diagram illustrating a configuration of a gNB (network node) according to an embodiment. FIG. 4 is a diagram illustrating a protocol stack configuration of a radio interface of a user plane that handles data. FIG. 5 is a diagram illustrating a protocol stack configuration of a radio interface of a control plane that handles signaling (control signals). FIG. 6 is a diagram illustrating a functional block configuration of AI / ML technology in a mobile communication system according to an embodiment. FIG. 7 is a diagram for explaining an overview of network slicing technology. FIG. 8 is a diagram for explaining an example of an operation scenario of a mobile communication system according to an embodiment. FIG. 9 is a diagram for explaining a first operation pattern of a mobile communication system according to an embodiment. FIG. 10 is a diagram for explaining an example of the first operation pattern of a mobile communication system according to an embodiment. FIG. 11 is a diagram for explaining a second operation pattern of a mobile communication system according to an embodiment. FIG. 12 is a diagram illustrating an example of the second operation pattern of a mobile communication system according to an embodiment.

[0009] A possible use case of the AI / ML technology is mobility control (e.g., handover control) of a user equipment. For example, assuming network slicing technology, a network node may determine a target cell for handover of a user equipment by model inference, thereby enabling a more appropriate determination of the target cell taking into account the network slice. However, a technology for implementing such AI / ML-based mobility control in combination with network slicing technology has not yet been established.

[0010] The present disclosure provides for facilitating AI / ML-based mobility control that takes network slices into consideration.

[0011] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0012] (1) Configuration of a Mobile Communication System First, the configuration of a mobile communication system according to an embodiment will be described. FIG. 1 is a diagram showing the configuration of a mobile communication system 1 according to an embodiment. The mobile communication system 1 conforms to the 5th Generation System (5GS) of the 3GPP standard. In the following description, 5GS will be used as an example, but the LTE (Long Term Evolution) system may also be applied at least in part to the mobile communication system. The 6th Generation (6G) system may also be applied at least in part to the mobile communication system.

[0013] The mobile communication system 1 includes a user equipment (UE) 100, a 5G radio access network (NG-RAN: Next Generation Radio Access Network) 10, and a 5G core network (5GC: 5G Core Network) 20. Hereinafter, the NG-RAN 10 may be simply referred to as the RAN 10. Furthermore, the 5GC 20 may be simply referred to as the core network (CN) 20. The RAN 10 and the CN 20 constitute a network 5 of the mobile communication system 1. The UE 100 performs wireless communication with the network 5.

[0014] The UE 100 is a mobile wireless communication device. The UE 100 may be any device that is used by a user. For example, the UE 100 may be a mobile phone terminal (which may be a smartphone), a tablet terminal, a notebook PC, a communication module (which may be a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0015] The NG-RAN 10 includes a base station 200 (also referred to as a "gNB" or "NG-RAN node" in a 5G system), which is a type of network node. The gNBs 200 are connected to each other via an Xn interface, which is an interface between base stations. The gNB 200 manages one or more cells. The gNB 200 performs wireless communication with a UE 100 that has established a connection with its own cell. The gNB 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, etc. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate a function or resource for wireless communication with the UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0016] In addition, gNBs can also be connected to the Evolved Packet Core (EPC), which is the core network of LTE. LTE base stations can also be connected to 5GC. LTE base stations and gNBs can also be connected via an inter-base station interface.

[0017] The 5GC20 includes an AMF (Access and Mobility Management Function) and a UPF (User Plane Function) 300. The AMF performs various mobility controls for the UE 100. The AMF manages the mobility of the UE 100 by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF controls data forwarding. The AMF and the UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0018] 2 is a diagram showing the configuration of a UE 100 (user equipment) according to an embodiment. The UE 100 has a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a communication unit that performs wireless communication with the gNB 200. The UE 100 is an example of a communication device.

[0019] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

[0020] The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0021] The control unit 130 performs various controls and processes in the UE 100. The operations of the UE 100 described above and below may be operations controlled by the control unit 130. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0022] 3 is a diagram showing the configuration of a gNB 200 (network node) according to an embodiment. The gNB 200 has a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240. The transmitter 210 and the receiver 220 constitute a communication unit that performs wireless communication with the UE 100. The backhaul communication unit 240 constitutes a network communication unit that communicates with the CN 20. The gNB 200 is another example of a communication device.

[0023] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[0024] The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

[0025] The control unit 230 performs various controls and processes in the gNB 200. The operations of the gNB 200 described above and below may be operations under the control of the control unit 130. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0026] The backhaul communication unit 240 is connected to adjacent base stations via an Xn interface, which is an interface between base stations. The backhaul communication unit 240 is connected to the AMF / UPF 300 via an NG interface, which is an interface between a base station and a core network. The gNB 200 may be configured (i.e., functionally divided) with a central unit (CU) and a distributed unit (DU), and the two units may be connected via an F1 interface, which is a fronthaul interface.

[0027] FIG. 4 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0028] The user plane air interface protocol includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0029] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of gNB200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from gNB200 on a physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires successfully decoded DCI as DCI addressed to the UE. The DCI transmitted from gNB200 has a CRC (Cyclic Redundancy Code) parity bit scrambled by the RNTI added.

[0030] In NR, UE100 can use a bandwidth narrower than the system bandwidth (i.e., the cell bandwidth). The gNB200 configures the UE100 with a bandwidth portion (BWP) consisting of contiguous PRBs (Physical Resource Blocks). The UE100 transmits and receives data and control signals in the active BWP. For example, up to four BWPs may be configurable for the UE100. Each BWP may have a different subcarrier spacing. The BWPs may overlap in frequency. When multiple BWPs are configured for the UE100, the gNB200 can specify which BWP to apply by controlling the downlink. This allows the gNB200 to dynamically adjust the UE bandwidth according to the amount of data traffic of the UE100, etc., thereby reducing UE power consumption.

[0031] The gNB 200 can configure, for example, up to three control resource sets (CORESETs) for each of up to four BWPs on the serving cell. The CORESET is a radio resource for control information to be received by the UE 100. Up to 12 or more CORESETs may be configured on the serving cell for the UE 100. Each CORESET may have an index of 0 to 11 or more. The CORESET may consist of six resource blocks (PRBs) and one, two, or three consecutive Orthogonal Frequency Division Multiplex (OFDM) symbols in the time domain.

[0032] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the gNB 200 via a transport channel. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE 100.

[0033] The RLC layer transmits data to the receiving RLC layer using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the gNB 200 via a logical channel.

[0034] The PDCP layer performs header compression / decompression, encryption / decryption, and the like.

[0035] The SDAP layer maps IP flows, which are units for Quality of Service (QoS) control by the core network, to radio bearers, which are units for QoS control by the access stratum (AS). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0036] FIG. 5 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals).

[0037] The protocol stack of the radio interface of the control plane includes a radio resource control (RRC) layer and a non-access stratum (NAS) instead of the SDAP layer shown in FIG.

[0038] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of gNB200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of gNB200 is suspended, UE100 is in an RRC inactive state.

[0039] The NAS, which is located above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS of the UE 100 and the NAS of the AMF 300A. Note that the UE 100 has an application layer and the like in addition to the radio interface protocol. Also, a layer lower than the NAS is called an AS (Access Stratum).

[0040] (2) Overview of AI / ML Technology Next, an overview of the AI / ML technology will be described. Fig. 6 is a diagram showing a functional block configuration of the AI / ML technology in the mobile communication system 1 according to the embodiment.

[0041] The functional block configuration shown in FIG. 6 includes a data collection unit A1, a model learning unit A2, a model inference unit A3, and a data processing unit A4.

[0042] The data collection unit A1 collects input data, specifically, learning data and inference data, outputs the learning data to the model learning unit A2, and outputs the inference data to the model inference unit A3. The data collection unit A1 may acquire data in the device on which the data collection unit A1 is provided as input data. The data collection unit A1 may also acquire data in another device as input data.

[0043] The model learning unit A2 performs model learning (also referred to as "learning processing"). Specifically, the model learning unit A2 optimizes parameters of a learning model (hereinafter also referred to as a "model" or an "AI / ML model") through machine learning using learning data, derives (generates and updates) a learned model, and outputs the learned model to the model inference unit A3. The model is a data-driven algorithm that applies AI / ML technology to generate a set of outputs based on a set of inputs. For example, considering y = ax + b, a (slope) and b (intercept) are parameters, and optimizing these corresponds to machine learning. Generally, machine learning is classified into supervised learning, unsupervised learning, and reinforcement learning. Supervised learning is a method that uses correct answer data as learning data. Unsupervised learning is a method that does not use correct data for training data. For example, in unsupervised learning, feature points are memorized from a large amount of training data and the correct answer is determined (range estimation). Reinforcement learning is a method that assigns a score to the output result and learns how to maximize the score.

[0044] The model inference unit A3 performs model inference (also referred to as "inference processing"). Specifically, the model inference unit A3 infers an output from inference data using a trained model and outputs the inference result data to the data processing unit A4. For example, in the case of y = ax + b, x corresponds to the inference data and y corresponds to the inference result data. Note that "y = ax + b" is a model. A model in which the slope and intercept are optimized, for example, "y = 5x + 3", is a trained model. There are various modeling techniques, including linear regression analysis, neural networks, and decision tree analysis. The above "y = ax + b" can be considered a type of linear regression analysis. The model inference unit A3 may provide model performance feedback to the model learning unit A2.

[0045] The data processing unit A4 receives the inference result data and performs processing that utilizes the inference result data.

[0046] (3) Overview of Network Slicing Technology Next, an overview of the network slicing technology will be described. Fig. 7 is a diagram for explaining the overview of the network slicing technology.

[0047] In network slicing, the network 5 is logically divided into network slices (hereinafter also simply referred to as "slices"). Each slice corresponds to a different service requirement. In the illustrated example, the network 5 has four slices (slices 1 to 4).

[0048] A network slice consists of a RAN part and a CN part. Support for network slicing is based on the principle that traffic of different slices is handled by different protocol data unit (PDU) sessions. The network 5 can realize various network slices by scheduling and by providing different Layer 1 / Layer 2 (L1 / L2) configurations.

[0049] Each network slice is uniquely identified by a Single Network Slice Selection Assistance Information (S-NSSAI), which contains one or a list of S-NSSAIs. The S-NSSAI has a required Slice / Service Type (SST) field that identifies the slice type and an optional Slice Differentiator (SD) field that distinguishes between slices with the same SST field.

[0050] If the NSSAI is provided by the NAS, the UE 100 provides the NSSAI for network slice selection to the network 5 (NG-RAN 10 / gNB 200) in an RRC Setup Complete message. The network 5 can support multiple slices, but the UE 100 does not need to support more than eight slices simultaneously. The NG-RAN 10 supports the selection of the RAN part of the network slice using the NSSAI provided by the UE 100 or the 5GC 20. Note that one gNB 200 (NG-RAN node) can support multiple slices.

[0051] The NG-RAN 10 supports resource separation between slices and can assign dedicated NG-RAN resources to certain slices. Some Random Access Channel (RACH) resources are associated with a specific Network Slice AS Group (NSAG). An NSAG identifies an association to a slice or a set of slices. That is, an NSAG indicates a slice group consisting of at least one slice. An NSAG is defined within a Tracking Area (TA) and is used for slice-based cell reselection and / or slice-based random access (slice-based RACH configuration).

[0052] (4) Operation of the Mobile Communication System Next, an operation of the mobile communication system 1 according to the embodiment will be described. In the embodiment, the AI / ML technology is applied to mobility control of the UE 100. Specifically, in the embodiment, the AI / ML technology is applied to control cell switching from a source cell to a target cell, specifically, switching of the serving cell of the UE 100. As an example, in the embodiment, a handover in which the primary cell (PCell) of the UE 100 is switched under the initiative of the RRC layer when the UE 100 is in an RRC connected state will be mainly described.

[0053] In addition to handover, cell switching when UE 100 is in the RRC connected state includes PSCell change, which switches the primary / secondary cell (PSCell) of UE 100 at the initiative of the RRC layer, and LTM (L1 / L2 Triggered Mobility), which is cell switching at the initiative of Layer 1 and / or Layer 2 (L1 / L2). In the embodiment, an example of applying AI / ML technology to handover will be mainly described, but AI / ML technology may also be applied to LTM or PSCell change. That is, "handover" described below may be read as "LTM" or "PSCell change." In LTM, for example, gNB200 pre-configures one or more candidate cells in UE100 using an RRC message, UE100 reports the cell measurement results to gNB200 via L1, gNB200 instructs UE100 to switch to the target cell using a MAC CE (Control Element), and UE100 accesses the target cell in accordance with the instruction.

[0054] Handover includes a general handover (also referred to as "HO") and a conditional handover (CHO: Conditional Handover). In a general handover, the UE 100 transmits a measurement report message, which is a type of RRC message, to the gNB 200, the gNB 200 determines a target cell based on the Measurement Report message, the gNB 200 instructs the UE 100 to handover to the target cell by an RRC message, and the UE 100 accesses the target cell in accordance with the instruction. In contrast, in conditional handover, the gNB 200 pre-sets one or more candidate cells together with handover execution conditions to the UE 100 by an RRC message, and the UE 100 evaluates whether the handover execution conditions to any of the candidate cells are met. The UE 100 determines the candidate cell for which the handover execution conditions are met as the target cell and accesses the target cell. Note that the cell that the UE 100 has determined to access is referred to as the target cell, and a cell that is a candidate for the target cell is referred to as a candidate cell. However, in the following, the terms "target cell" and "candidate cell" may be used as synonyms.

[0055] Also, from the viewpoint of the network 5, handovers include intra-gNB (intra-CU) handovers in which the source cell and the target cell belong to the same gNB (CU), and inter-gNB (inter-CU) handovers in which the source cell and the target cell belong to different gNBs (CU). In the embodiment, inter-gNB handovers are mainly assumed, but intra-gNB handovers may also be assumed.

[0056] Furthermore, in the following embodiments, an example will be mainly described in which AI / ML-related signaling related to the AI / ML technology is an RRC message, which is signaling of the RRC layer (i.e., Layer 3). However, the AI / ML-related signaling may be MAC CE, which is signaling of the MAC layer (i.e., Layer 2), or downlink control information (DCI) and / or uplink control information (UCI), which are signaling of the PHY layer (i.e., L1). The downlink AI / ML-related signaling may be UE-dedicated signaling or broadcast signaling (e.g., SIB (System Information Block)). The AI / ML-related signaling may be signaling in a new layer (e.g., the AI / ML layer) dedicated to artificial intelligence or machine learning.

[0057] FIG. 8 is a diagram for explaining an example of an operation scenario of the mobile communication system 1 according to the embodiment.

[0058] In the illustrated example, UE100 is in an RRC connected state with cell a managed by gNB200a as the serving cell. That is, UE100 has established an RRC connection with gNB200a and is performing wireless communication with gNB200a. Cell b and cell c are neighboring cells of cell a. Cell b is managed by gNB200b, and cell c is managed by gNB200c. gNB200a is communicably connected to gNB200b and gNB200c via an inter-node interface (Xn interface).

[0059] As the UE 100 moves, it is necessary to perform handover of the UE 100 from the cell a to a neighboring cell. In the illustrated example, the neighboring cells are cell b and cell c, and cell b and cell c are candidate cells for handover.

[0060] In a typical handover, UE100 sends a Measurement Report message, which is a type of RRC message, to gNB200, and gNB200 determines one of cell b and cell c as the target cell based on the Measurement Report message, and gNB200 instructs UE100 to perform a handover to the target cell via an RRC message, and UE100 accesses the target cell in accordance with the instruction.

[0061] In the case of conditional handover, gNB200 pre-configures one or more candidate cells (cell b and cell c) along with handover execution conditions to UE100 via an RRC message, UE100 evaluates whether the handover execution conditions to any of the candidate cells are met, and UE100 determines the candidate cell for which the handover execution conditions are met as the target cell and accesses the target cell.

[0062] In such handovers (general handovers and conditional handovers), if the target cell (target gNB) does not support the network slice that UE 100 is using or intends to use, problems such as service interruptions may occur. Also, even if the target cell (target gNB) supports the network slice that UE 100 is using, if the target cell (target gNB) experiences a resource shortage for the network slice during handover, the required service quality may not be met.

[0063] Here, by having the gNB 200a determine the target cell (target gNB) for handover of the UE 100 by model inference, it may be possible to more appropriately determine the target cell taking into account the network slice. In the embodiment, a first operation pattern and a second operation pattern of the mobile communication system 1 for facilitating AI / ML-based mobility control taking into account the network slice will be described.

[0064] (4.1) First Operation Pattern FIG. 9 is a diagram for explaining the first operation pattern of the mobile communication system 1 according to the embodiment.

[0065] The UE 100 is in an RRC connected state with cell a managed by the gNB 200a as the serving cell. The UE 100 performs wireless communication with the gNB 200a using at least one network slice. In a first operation pattern, the UE 100 transmits slice-related information used to control the mobility of the UE 100 to the gNB 200. The slice-related information includes at least one of first information indicating the usage probability of each network slice, second information indicating the priority of each network slice, and third information indicating the traffic pattern of each network slice. That is, the UE 100 notifies the gNB 200a of at least one of the usage probability of each slice, the priority of each slice, and the traffic pattern (resource occupancy rate) of each slice.

[0066] This allows gNB200a (source gNB) to appropriately determine the target cell (target gNB) taking into account the network slice based on slice-related information provided by UE100.

[0067] The UE 100 that performs such operations has a control unit 130 that performs wireless communication with the gNB 200a using at least one network slice, and a transmission unit 120 that transmits slice-related information to the gNB 200a that is used to perform mobility control of the UE 100. On the other hand, the gNB 200a has a control unit 230 that performs wireless communication with the UE 100 using at least one network slice, and a reception unit 220 that receives slice-related information from the UE 100 that is used to perform mobility control of the UE 100.

[0068] In the first operation pattern, the UE 100 may receive signaling from the gNB 200a requesting or configuring the transmission of slice-related information. The UE 100 may transmit the slice-related information to the gNB 200a based on the signaling.

[0069] In the first operation pattern, the UE 100 may derive at least one of the first information, the second information, and the third information by statistical processing based on the UE 100's past use of each network slice.

[0070] In the first operation pattern, the UE 100 may derive at least one of the first information, the second information, and the third information by an inference process (model inference) using an artificial intelligence or machine learning (AI / ML) model based on a history of past use of each network slice by the UE 100. Here, the AI / ML model may be a trained model that has learned about a history of past use of each network slice by the UE 100.

[0071] In the first operation pattern, at least one of the first information, the second information, and the third information may be information in S-NSSAI units or information in NSAG units.

[0072] 10 is a diagram illustrating an example of a first operation pattern of the mobile communication system 1 according to the embodiment. Note that the gNB 200a may be provided with information (for example, Allowed NSSAI, Configured NSSAI) on the network slice that the UE 100 is permitted to use from the AMF 300A.

[0073] In step S101, the UE 100 is in an RRC connected state with a cell a managed by the gNB 200a as a serving cell. The UE 100 is performing wireless communication with the cell a (gNB 200a) using at least one network slice.

[0074] In step S102, the gNB 200a may transmit a transmission setting or a transmission request for slice-related information (also referred to as a "slice information request") to the UE 100. The UE 100 receives the slice information request.

[0075] The gNB200a may include the slice information request in an RRC Reconfiguration message, which is a type of RRC message, and transmit it to the UE100. The RRC Reconfiguration message may include a measurement configuration for configuring the UE100 to perform measurements and measurement reports for handover. That is, the gNB200 may transmit the slice information request to the UE100 together with the measurement configuration. The slice information request may be included in the measurement configuration.

[0076] The gNB200 may include information indicating the network slice to which the slice-related information is applied (or the network slice not to which the slice-related information is applied) in the slice information request. The information may be a list of S-NSSAIs or a list of NSAGs.

[0077] The gNB 200 may include in the slice information request information indicating the type of slice-related information to be requested from the UE 100. For example, the gNB 200 may include in the slice information request information indicating the type of information to be derived and transmitted by the UE 100 from among the first information to the third information.

[0078] When gNB200 requests UE100 for statistical values ​​based on past history (performance), gNB200 may include information indicating the target period (e.g., the past one day) in the slice information request.

[0079] When gNB200 requests UE100 for a future prediction value using model inference, it may include identification information (model ID or function ID) of the AI / ML model used for model inference in the slice information request. Alternatively, gNB200 may include the AI / ML model itself in the slice information request.

[0080] In step S103, the UE 100 transmits slice-related information to the gNB 200a. The gNB 200a receives the slice-related information. The UE 100 may transmit the slice-related information to the gNB 200a by including it in a Measurement Report message or a UE Assistance Information message, which is a type of RRC message. The slice-related information includes at least one of the following first to third information.

[0081] 1) Information indicating the usage probability of each network slice (first information): The first information may include, for each network slice, an S-NSSAI indicating the network slice and information indicating the probability that the UE 100 uses the network slice. For example, the first information may be information such as S-NSSAI#1: 30%, S-NSSAI#2: 15%, S-NSSAI#3: 60%, etc. However, the information indicating the probability may be an index indicating the probability instead of a probability value. For example, the first information may be information such as S-NSSAI#1: high probability (high), S-NSSAI#2: low probability (low), S-NSSAI#3: medium probability (middle), etc.

[0082] The first information may include, for each set (group) of network slices, an NSAG indicating the set and information indicating a probability that the set is used by the UE 100. For example, the first information may be information such as NSAG #1: 30%, NSAG #2: 15%, NSAG #3: 60%, ...

[0083] The UE 100 may derive the usage probability of each network slice by statistical processing (e.g., maximum, minimum, or average) based on the past usage history of each network slice by the UE 100. The UE 100 may derive the usage probability of each network slice by model inference using an AI / ML model (trained model) that has learned about the past usage history of each network slice by the UE 100.

[0084] 2) Information indicating the priority of each network slice (second information): The second information may include, for each network slice, an S-NSSAI indicating the network slice and information indicating the priority (priority order) derived for the network slice by the UE 100. For example, the first information may be information such as S-NSSAI#1: priority "3", S-NSSAI#2: priority "1", S-NSSAI#3: priority "2", ...

[0085] The second information may include, for each set (group) of network slices, an NSAG indicating the set and information indicating a priority (priority order) derived for the set by the UE 100. For example, the second information may be information such as NSAG #1: priority "3", NSAG #2: priority "1", NSAG #3: priority "2", ...

[0086] The UE 100 may derive the priority of each network slice by statistical processing based on the past use history of each network slice by the UE 100. For example, the UE 100 may calculate the usage probability of each network slice by statistical processing as described above, and then derive a higher priority as the calculated usage probability is higher. The UE 100 may derive the priority of each network slice by model inference using an AI / ML model (trained model) that has learned about the past use history of each network slice by the UE 100.

[0087] 3) Information indicating a traffic pattern of each network slice (third information): The traffic pattern may be at least one of a traffic period (occurrence period), a data amount of one burst (throughput), and a period (duration) of one burst. A burst may be data per transmission (or reception). The third information may be information indicating separate traffic patterns for the uplink and downlink of each network slice.

[0088] The third information may include, for each network slice, an S-NSSAI indicating the network slice and information indicating a traffic pattern derived for the network slice by the UE 100. The third information may include, for each set (group) of network slices, an NSAG indicating the set and information indicating a traffic pattern derived for the set by the UE 100.

[0089] The UE 100 may derive the traffic pattern of each network slice by statistical processing (e.g., maximum, minimum, or average) based on the past use history of each network slice by the UE 100. The UE 100 may derive the traffic pattern of each network slice by model inference using an AI / ML model (trained model) that has learned about the past use history of each network slice by the UE 100.

[0090] In step S104, the gNB 200a determines a target cell for handover of the UE 100 based on the slice-related information received from the UE 100 in step S103. The gNB 200a may determine the target cell by model inference based on the slice-related information using an AI / ML model. Here, it is assumed that cell b is determined as the target cell.

[0091] The gNB200a may know in advance the network slices and / or the communication capacity of each network slice supported by each candidate cell. Here, the candidate cell may be a cell (neighbor cell) that satisfies a predetermined radio quality standard. The gNB200a may determine the candidate cell based on a Measurement Report message from the UE100. The gNB200a may determine, as a target cell, a candidate cell that supports a network slice with a high usage probability and / or priority of the UE100 based on the first information and / or the second information included in the slice-related information. The gNB200a may estimate the radio resource load (rate) for each candidate cell based on the third information included in the slice-related information, and select, as a target cell, a candidate cell having a communication capacity that can withstand the load.

[0092] In step S105, gNB200a transmits an HO Request message to gNB200b, which manages cell b, requesting handover of UE100. gNB200b receives the HO Request message. gNB200a may transmit the HO Request message to gNB200b, including at least a portion of the slice-related information received from UE100 in step S103 and / or information indicating the radio resource load estimated based on the slice-related information.

[0093] In step S106, in response to receiving the HO Request message, the gNB 200b transmits an HO Request Acknowledge message to the gNB 200a. The HO Request Acknowledge message includes setting information (RRC setting information) necessary for the UE 100 to access the target cell (cell b).

[0094] In step S107, in response to receiving the HO Request Acknowledge message in step S106, the gNB 200a transmits an RRC Reconfiguration message including the RRC setting information in the HO Request Acknowledge message as an HO command to the UE 100. The UE 100 receives the HO command.

[0095] In step S108, in response to receiving the HO command in step S107, the UE 100 accesses cell b, which is the target cell (connection process). For example, the UE 100 may start a random access procedure for cell b and transmit a random access preamble to cell b. Thereafter, the UE 100 may transmit an RRC Reconfiguration Complete message to cell b. When such connection process is completed, the UE 100 continues communication with cell b as a new serving cell.

[0096] In this operation example, the operation in the case of a general handover has been described as an example, but it may also be applied to a conditional handover. For example, the gNB 200a may determine one or more candidate cells based on slice-related information from the UE 100, and set these candidate cells together with handover execution conditions to the UE 100 by an RRC message. When the handover execution condition to any of the candidate cells is met, the UE 100 may access the candidate cell where the handover execution condition is met as the target cell.

[0097] (4.2) Second Operation Pattern Fig. 11 is a diagram for explaining a second operation pattern of the mobile communication system 1 according to the embodiment. The second operation pattern may be implemented in combination with the first operation pattern.

[0098] In the second operation pattern, gNB200a acquires slice load information indicating the load status of each network slice related to another gNB200 (neighboring gNB) from the other gNB200. In the illustrated example, gNB200a acquires slice load information indicating the load status of each network slice related to gNB200b (cell b) from gNB200b, and acquires slice load information indicating the load status of each network slice related to gNB200c (cell c) from gNB200c. Based on the acquired slice load information, gNB200a performs mobility control from gNB200a to another gNB200 (target cell). For example, gNB200a determines the target (target cell and / or target gNB) of handover of UE100 based on the acquired slice load information. The gNB200a may predict whether slice service will be provided properly at the target after handing over the UE100, and may hand over the UE100 to a target that is predicted to provide slice service properly.

[0099] 12 is a diagram showing an example of the second operation pattern of the mobile communication system 1 according to the embodiment. Here, differences from the first operation pattern will be mainly described.

[0100] In step S201, the UE 100 is in an RRC connected state with a cell a managed by the gNB 200a as a serving cell. The UE 100 is performing wireless communication with the cell a (gNB 200a) using at least one network slice.

[0101] In step S202, gNB200a may send a slice information request to UE100.

[0102] In step S203, gNB200a may transmit a RESOURCE STATUS REQUEST message to gNB200b to request a report of the resource load status of gNB200b, which is a neighboring gNB. The RESOURCE STATUS REQUEST message may include information indicating a cell to be reported (e.g., cell b), information requesting the start of measurement of the resource load status, and information indicating a reporting period. In a second operation pattern, the RESOURCE STATUS REQUEST message may include at least one of information indicating a type of slice load information to be reported and information indicating a slice to be reported.

[0103] In step S204, in response to receiving the RESOURCE STATUS REQUEST message in step S203, gNB200b may send a RESOURCE STATUS RESPONSE message to gNB200a and start the measurements requested by gNB200a.

[0104] In step S205, UE100 may transmit slice-related information to gNB200a.

[0105] In step S206, gNB200b transmits a RESOURCE STATUS UPDATE message including slice load information (information regarding the load for each slice) to gNB200a. gNB200a receives the RESOURCE STATUS UPDATE message. The RESOURCE STATUS UPDATE message may include cell identification information indicating the reporting cell (cell b) and slice load information associated with the cell identification information. The slice load information includes at least one of the following information 1) to 3).

[0106] 1) Information on the number of UEs 100 in an RRC connected state per network slice (RRC connection number information): The RRC connection number information is information on the number of RRC connections per slice of a cell. The RRC connection number information may include a value of the number of RRC connections (integer type) per slice of a cell and a value of the available RRC connection capacity per slice of a cell. The value of the number of RRC connections (integer type) per slice of a cell may be the number of RRC connections (the number of UEs 100 in an RRC connected state) for which PDU sessions associated with the slice have been established. The value of the available RRC connection capacity per slice of a cell is a percentage of the remaining number of current RRC connections of the slice with respect to the maximum number of RRC connections supported by the slice. For example, if the maximum number of RRC connections supported by slice #1 is 100 and the current number of RRC connections of the slice is 25, the value of the available RRC connection capacity is 75%.

[0107] For example, the RRC connection number information may be information such as S-NSSAI#1: RRC connection number "25" and available RRC connection capacity 30[%], S-NSSAI#2: RRC connection number "20" and available RRC connection capacity 45[%], etc.

[0108] In addition, instead of the number of RRC connections (the number of UEs 100 in the RRC connected state), the number of RRC inactives (the number of UEs 100 in the RRC inactive state) may be used, or the sum of the number of RRC connections and the number of RRC inactives may be used.

[0109] 2) Information on the number of UEs 100 that are in an RRC connected state and are active per network slice (active UE number information): The active UE number information may be an average value (integer type) of the number of active UEs per slice of a cell. The active UE number may be UEs that have data available for transmission. The active UE number information may be, for example, information such as S-NSSAI#1: active UE number "25", S-NSSAI#2: active UE number "20", ...

[0110] 3) Information regarding communication load (amount of used resources) per UE for each network slice: This information may be the average resource (load) consumed per UE for each slice of a cell. For example, this information may be an integer (0 to 100) indicating that the resource consumed (on average) per UE is 2% of the total capacity of the slice. This information may be, for example, S-NSSAI#1: average resource usage per UE is 2%; S-NSSAI#2: average resource usage per UE is 5%.

[0111] In step S207, gNB200a determines whether to set cell b as the target cell based on the slice load information received from gNB200a in step S206. For example, gNB200a determines as the target cell a candidate cell that supports the network slice used by UE100 and in which the load of the network slice is low. gNB200 may also determine the target cell based on the slice-related information received from UE100 in step S205. For example, gNB200a may use model inference using an AI / ML model to estimate the load increase (amount of resources consumed by UE100) for each slice of each candidate cell after handover of UE100, and determine the candidate cell with the lowest estimated load as the target cell.

[0112] In step S208, gNB200a transmits an HO Request message to gNB200b, which manages cell b, requesting handover of UE100. gNB200b receives the HO Request message. gNB200a may include at least a portion of the slice-related information received from UE100 in step S205 and / or information indicating the load estimated in step S207 in the HO Request message and transmit it to gNB200b.

[0113] In step S209, in response to receiving the HO Request message, the gNB 200b transmits an HO Request Acknowledge message to the gNB 200a. The HO Request Acknowledge message includes setting information (RRC setting information) necessary for the UE 100 to access the target cell (cell b).

[0114] In step S210, in response to receiving the HO Request Acknowledge message in step S209, the gNB 200a transmits an RRC Reconfiguration message including the RRC setting information in the HO Request Acknowledge message as an HO command to the UE 100. The UE 100 receives the HO command.

[0115] In step S211, in response to receiving the HO command in step S107, the UE 100 accesses cell b, which is the target cell (connection process). For example, the UE 100 may start a random access procedure for cell b and transmit a random access preamble to cell b. Thereafter, the UE 100 may transmit an RRC Reconfiguration Complete message to cell b. When such connection process is completed, the UE 100 continues communication with cell b as a new serving cell.

[0116] In step S212, the gNB200b may transmit a RESOURCE STATUS UPDATE message including slice load information (information regarding the load for each slice) to the gNB200a. The RESOURCE STATUS UPDATE message of step S212 may include information regarding the load fluctuation amount of the gNB200b (cell b) due to the handed over UE100, in addition to or instead of the information in the RESOURCE STATUS UPDATE message of step S206. This information includes at least one of the following information 1) and 2). The gNB200a may perform model learning of the AI / ML model using the information in the RESOURCE STATUS UPDATE message of step S212.

[0117] 1) Information indicating the amount of resources (load) consumed by each slice for the handed over UE 100: This information may be information indicating the amount of resources (load) consumed by the UE 100 in cell b after handover for each slice.

[0118] 2) Information about the estimated load and the actual load notified in step S208: This information may be the difference between these loads. This information may also be information about whether the estimation was correct.

[0119] In this operation example, the operation in the case of a general handover has been described as an example, but it may also be applied to a conditional handover. For example, the gNB 200a may determine one or more candidate cells based on slice load information from neighboring gNBs, and set these candidate cells together with handover execution conditions to the UE 100 by an RRC message. When the handover execution condition to any candidate cell is satisfied, the UE 100 may access the candidate cell for which the handover execution condition is satisfied as the target cell.

[0120] (5) Other Embodiments The above-described operational flows are not limited to being implemented independently, but can be implemented by combining two or more operational flows. For example, some steps of one operational flow may be added to another operational flow, or some steps of one operational flow may be replaced with some steps of another operational flow. In each flow, it is not necessary to execute all steps, and only some steps may be executed.

[0121] In the above embodiment, an example in which the base station is an NR base station (gNB) has been described, but the base station may also be an LTE base station (eNB). The base station may also be a relay node such as an IAB (Integrated Access and Backhaul) node. The base station may also be a DU (Distributed Unit) of the IAB node. The user equipment (terminal device) may also be a relay node such as an IAB node, or an MT (Mobile Termination) of the IAB node.

[0122] That is, the UE 100 may be a terminal function unit (a type of communication module) for a base station to control a repeater that relays signals. Such a terminal function unit is referred to as an MT. Examples of the MT include, in addition to the IAB-MT, an NCR (Network Controlled Repeater)-MT and a RIS (Reconfigurable Intelligent Surface)-MT.

[0123] Furthermore, the term "network node" primarily refers to a base station, but may also refer to a core network device or a part of a base station (CU, DU, or RU). A network node may also be a combination of at least a part of a core network device and at least a part of a base station.

[0124] A program may be provided that causes a computer to execute each process performed by a communication device (for example, UE 100 or gNB 200). The program may be recorded on a computer-readable medium. Using a computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or DVD-ROM. Furthermore, circuits that execute each process performed by the communication device may be integrated, and at least a part of the communication device may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0125] The functions performed by the UE 100 or the gNB 200 (network node) may be implemented in circuitry or processing circuitry, including general-purpose processors, application-specific processors, integrated circuits, ASICs (Application Specific Integrated Circuits), CPUs (Central Processing Units), conventional circuits, and / or combinations thereof, programmed to perform the described functions. A processor includes transistors and other circuits and is considered to be circuitry or processing circuitry. A processor may also be a programmed processor that executes a program stored in memory. In this specification, circuitry, unit, or means refers to hardware that is programmed to perform the described functions or hardware that executes them. The hardware may be any hardware disclosed herein or any hardware known to be programmed or capable of performing the described functions. If the hardware is a processor, the circuitry, means, or unit is a combination of hardware and software used to configure the hardware and / or processor.

[0126] As used in this disclosure, the terms "based on" and "depending on" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "based only on" and "at least in part on." Furthermore, "obtain" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating the information. The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may also mean including only the listed items or including additional items in addition to the listed items. Furthermore, as used in this disclosure, the term "or" is not intended to mean an exclusive or. Furthermore, any reference to an element using a designation such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, reference to a first and a second element does not imply that only two elements may be employed therein, or that the first element must precede the second element in some way. In this disclosure, when articles are added by translation, such as a, an, and the in English, these articles are intended to include the plural unless the context clearly dictates otherwise.

[0127] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention.

[0128] This application claims priority from Japanese Patent Application No. 2023-133595 (filed August 18, 2023), the entire contents of which are incorporated herein by reference.

[0129] (6) Supplementary Notes The following are additional notes regarding the features of the above-described embodiment.

[0130] (Supplementary Note 1) A communication method used in a mobile communication system, comprising: a step in which a user equipment performs wireless communication with a network node using at least one network slice; and a step in which the user equipment transmits slice-related information used to perform mobility control of the user equipment to the network node, wherein the slice-related information includes at least one of first information indicating the usage probability of each network slice, second information indicating the priority of each network slice, and third information indicating the traffic pattern of each network slice.

[0131] (Supplementary Note 2) The communication method described in Supplementary Note 1 further comprises a step in which the user equipment receives signaling from the network node requesting or configuring transmission of the slice-related information, and the step of transmitting the slice-related information includes a step of transmitting the slice-related information to the network node based on the signaling.

[0132] (Supplementary Note 3) The communication method described in Supplementary Note 1 or 2, further comprising a step in which the user equipment derives at least one of the first information, the second information, and the third information by statistical processing based on the user equipment's past use of each network slice.

[0133] (Supplementary Note 4) The communication method according to any one of Supplementary Notes 1 to 3, further comprising a step in which the user device derives at least one of the first information, the second information, and the third information by an inference process using an artificial intelligence or machine learning (AI / ML) model based on the user device's past use of each network slice.

[0134] (Supplementary Note 5) At least one of the first information, the second information, and the third information is information in units of S-NSSAI (Single Network Slice Selection Assistance information) or information in units of NSAG (Network Slice AS Group). The communication method according to any one of Supplementary Notes 1 to 4.

[0135] (Supplementary Note 6) A communication method described in any of Supplementary Notes 1 to 5, further comprising: a step in which the network node receives the slice-related information from the user equipment; a step in which the network node acquires slice load information from another network node, the slice load information indicating the load status of each network slice related to the other network node; and a step in which the network node performs the mobility control from the network node to the other network node based on the slice-related information and the slice load information.

[0136] (Supplementary Note 7) The communication method according to Supplementary Note 6, wherein the slice load information includes information on the number of user equipments in a radio resource control (RRC) connected state for each network slice.

[0137] (Supplementary Note 8) The communication method according to Supplementary Note 6 or 7, wherein the slice load information includes information on the number of user equipments that are in a radio resource control (RRC) connected state and are active, for each network slice.

[0138] (Supplementary Note 9) The communication method according to any one of Supplementary Notes 6 to 8, wherein the slice load information includes information on a communication load per user device for each network slice.

[0139] (Supplementary Note 10) The communication method according to any one of Supplementary Notes 6 to 9, wherein the step of performing mobility control includes a step of determining a target of handover of the user equipment based on the slice-related information and the slice load information.

[0140] (Supplementary Note 11) A user equipment used in a mobile communication system, comprising: a control unit that performs wireless communication with a network node using at least one network slice; and a transmission unit that transmits slice-related information used to perform mobility control of the user equipment to the network node, wherein the slice-related information includes at least one of first information indicating the usage probability of each network slice, second information indicating the priority of each network slice, and third information indicating the traffic pattern of each network slice.

[0141] (Supplementary Note 12) A network node used in a mobile communication system, comprising: a control unit that performs wireless communication with a user device using at least one network slice; and a receiving unit that receives slice-related information from the user device used to perform mobility control of the user device, wherein the slice-related information includes at least one of first information indicating the usage probability of each network slice, second information indicating the priority of each network slice, and third information indicating the traffic pattern of each network slice.

[0142] (Supplementary Note 13) A network node used in a mobile communication system, comprising: a communication unit that transmits slice load information indicating the load status of each network slice to other network nodes, wherein the slice load information includes, for each network slice, at least one of information on the number of user equipments in a radio resource control (RRC) connected state, information on the number of user equipments that are in an RRC connected state and are active, and information on the communication load per user equipment.

[0143] 1: Mobile communication system 5: Network 10: RAN (NG-RAN) 20: CN (5GC) 100: UE 110: Receiving unit 120: Transmitting unit 130: Control unit 200: gNB 210: Transmitting unit 220: Receiving unit 230: Control unit 240: Backhaul communication unit A1: Data collection unit A2: Model learning unit A3: Model inference unit A4: Data processing unit

Claims

1. A communication method for use in a mobile communications system, comprising: a user equipment performing wireless communication with a network node using at least one network slice; and the user equipment transmitting slice-related information used to control mobility of the user equipment to the network node, wherein the slice-related information includes at least one of first information indicating a usage probability of each network slice, second information indicating a priority of each network slice, and third information indicating a traffic pattern of each network slice.

2. The communication method of claim 1, further comprising the user equipment receiving signaling from the network node requesting or configuring transmission of the slice-related information, and transmitting the slice-related information includes transmitting the slice-related information to the network node based on the signaling.

3. The communication method according to claim 1, further comprising the user equipment deriving at least one of the first information, the second information, and the third information by statistical processing based on the user equipment's past use of each network slice.

4. The communication method of claim 1, further comprising the user device deriving at least one of the first information, the second information, and the third information by inference processing using an artificial intelligence or machine learning (AI (Artificial Intelligence) / ML (Machine Learning)) model based on the user device's past use of each network slice.

5. The communication method according to any one of claims 1 to 4, wherein at least one of the first information, the second information, and the third information is information in units of S-NSSAI (Single Network Slice Selection Assistance information) or information in units of NSAG (Network Slice AS Group).

6. The communication method of claim 1, further comprising: the network node receiving the slice-related information from the user equipment; the network node acquiring slice load information from another network node, the slice load information indicating the load status of each network slice related to the other network node; and the network node performing the mobility control from the network node to the other network node based on the slice-related information and the slice load information.

7. The communication method according to claim 6, wherein the slice load information includes information regarding the number of user equipment in a radio resource control (RRC) connected state for each network slice.

8. The communication method according to claim 6, wherein the slice load information includes information regarding the number of user equipment devices that are in a radio resource control (RRC) connected state and are active for each network slice.

9. The communication method according to claim 6, wherein the slice load information includes information regarding the communication load per user device for each network slice.

10. The communication method according to claim 6, wherein performing the mobility control includes determining a handover target for the user equipment based on the slice-related information and the slice load information.

11. A user equipment for use in a mobile communications system, comprising: a control unit that performs wireless communication with a network node using at least one network slice; and a transmission unit that transmits slice-related information used to perform mobility control of the user equipment to the network node, wherein the slice-related information includes at least one of first information indicating a usage probability of each network slice, second information indicating a priority of each network slice, and third information indicating a traffic pattern of each network slice.

12. A network node used in a mobile communications system, comprising: a control unit that performs wireless communication with a user equipment using at least one network slice; and a receiving unit that receives slice-related information from the user equipment used to perform mobility control of the user equipment, wherein the slice-related information includes at least one of first information indicating a usage probability of each network slice, second information indicating a priority of each network slice, and third information indicating a traffic pattern of each network slice.

13. A network node used in a mobile communications system, comprising a communication unit that transmits slice load information indicating a load status of each network slice to other network nodes, wherein the slice load information includes at least one of information on the number of user equipment in a radio resource control (RRC) connected state, information on the number of user equipment that is in an RRC connected state and is active, and information on the communication load per user equipment, for each network slice.

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