WO2022176098A1

WO2022176098A1 - Terminal, base station, communication method, and program

Info

Publication number: WO2022176098A1
Application number: PCT/JP2021/006091
Authority: WO
Inventors: 克成上村
Original assignee: ソフトバンク株式会社
Priority date: 2021-02-18
Filing date: 2021-02-18
Publication date: 2022-08-25

Abstract

Provided is a terminal including an acquisition unit for acquiring slice information indicating network slices that can be provided by cells and slice additional information indicating network slice implementation methods; and a control unit for selecting or reselecting a cell to be camped on from among the cells that can provide the network slices on the basis of the slice information, the slice additional information, and a network slice implementation method supported by the terminal.

Description

Terminal, base station, communication method and program

The present invention relates to terminals, base stations, communication methods and programs.

　The 3GPP (3rd Generation Partnership Project), an international standardization body, is studying the 5G system (5GS: 5G System), which is the 5th generation (5G) cellular system.

For example, network slicing is being considered as a technology for operating an optimal network for 5G services. Network slicing is a technique of building multiple virtualized logical networks on a physical network in order to support the service requirements of a certain communication service. Each of these virtualized logical networks is called a network slice or simply a slice (Non-Patent Document 1).

According to the specifications currently being considered by 3GPP, a terminal transmits information indicating a desired network slice for registration to a cell selected by cell selection or reselection, thereby performing network registration processing. conduct. If the network cannot provide the network slice specified by the terminal, registration with the specified network slice will be refused.

However, according to the current specifications, the terminal cannot know whether the network slice for which it wishes to register is provided unless it performs the registration process with the network for the cell selected by cell selection or reselection. can't In addition, even if the network provides a network slice for which registration is desired, if the terminal does not support the implementation method of the network slice, wireless resources related to the registration process with the network are wasted. It may get lost.

Therefore, an object of the present invention is to provide a technology that enables selection or reselection of cells in consideration of a network slice implementation method.

A terminal according to an aspect of the present invention includes an acquisition unit that acquires slice information indicating a network slice that can be provided in a cell and slice additional information indicating a method for realizing the network slice, slice information, slice additional information, and a terminal. and a control unit that selects or reselects a cell to camp on from among cells that can provide network slices, based on the network slice implementation method supported by .

According to the present invention, it is possible to provide a technology that enables cell selection or reselection in consideration of the network slice implementation method.

1 is a diagram showing an example of an overview of a wireless communication system according to an embodiment; FIG. FIG. 2 is a diagram for explaining network slicing and network slicing; FIG. 1 is a diagram illustrating a conventional processing procedure when a terminal is registered with a network; FIG. FIG. 4 is a diagram showing the bit configuration of S-NSSAI; This is the definition of the SST Value. FIG. 4 is a diagram exemplifying correspondence relationships and contents of slice information and slice additional information; FIG. 2 is a diagram showing an example of hardware configurations of a terminal and a base station; FIG. FIG. 3 is a diagram showing a functional block configuration example of a terminal; FIG. 4 is a diagram for explaining an operation of changing/not changing the frequency priority of a cell; FIG. 4 is a diagram for explaining an operation of changing/not changing the frequency priority of a cell; FIG. 2 is a diagram showing an example of a functional block configuration of a base station; FIG. FIG. 4 is a flowchart showing an example of a processing procedure when a terminal selects or reselects a cell; FIG.

An embodiment of the present invention will be described with reference to the accompanying drawings. It should be noted that, in each figure, the same reference numerals have the same or similar configurations.

<System configuration>
The radio communication system according to the present embodiment targets a 5G system (5G system: 5GS) including a radio access network (RAN), a core network (CN), and a terminal, but is limited to this not. For example, it is also applicable to wireless communication systems adopting LTE and LTE-Advanced. In addition, the radio access network may operate with multiple RATs (multi-RAT) including LTE and/or LTE-Advanced and NR (described later), or operate with any one RAT (Radio Access Technology) You may LTE and/or LTE-Advanced is also called EUTRA (Evolved Universal Terrestrial Radio Access). 5G is also called NR (New Radio). This embodiment can be applied to any wireless communication system as long as it includes at least a terminal, a base station, and a core network.

FIG. 1 is a diagram showing an example of an outline of a wireless communication system 1 according to this embodiment. As shown in FIG. 1, the radio communication system 1 includes a terminal 10, base stations 20A-20B, and a core network 30. FIG. When the base stations 20A-20B and cells C1-C2 are not distinguished, they are collectively referred to as base station 20 and cell C, respectively. Also, the numbers of terminals 10 and base stations 20 shown in FIG. 1 are merely examples, and are not limited to the numbers shown.

The terminal 10 is, for example, a predetermined terminal, device, integrated circuit, or apparatus such as a smartphone, a personal computer, an in-vehicle terminal, an in-vehicle device, and a stationary device. The terminal 10 may also be called a user equipment (UE). The terminal 10 may be mobile or stationary. The terminal 10 can communicate with a RAT that adopts at least one of EUTRA and NR, for example.

For the base station 20, a base station for EUTRA (Evolved Universal Terrestrial Radio Access), a base station for NR, or a base station that supports both EUTRA and NR can be used. The base station 20 for EUTRA is called eNB (evolved NodeB), and the base station 20 for NR is called gNB (g-NodeB).

The base station 20 includes ng-eNB, gNodeB (gNB), en-gNB, Next Generation-Radio Access Network (NG-RAN) node, Donor eNodeB (DeNB), Donor node, Central Unit (CU), low power node ( low-power node), pico eNB, Home eNB (HeNB), Distributed Unit (DU), gNB-DU, Remote Radio Head (RRH), or Integrated Access and Backhaul/Backhauling (IAB) node, etc. good.

The base station 20 forms one or more cells C. Cell C is a serving cell, carrier, component carrier (CC), primary cell (PCell), secondary cell (Secondary Cell: SCell), primary secondary cell (Primary SCell), special cell (SpCell) ) and the like. Although the

base stations

20A and 20B form cells C1 and C2, respectively, in FIG. 1, each base station 20 may form a plurality of cells. Also, the plurality of base stations 20 may be connected to each other via a predetermined interface (eg, X2 or Xn interface).

The core network 30 is, for example, an EUTRA-compatible core network (Evolved Packet Core: EPC) or an NR-compatible core network (5G Core Network: 5GC). The core network 30 includes a plurality of entities such as AMF (Access and Mobility Management Function), SMF (Session Management Function), UPF (User Plane Function) and NSSF (Network Slice Selection Function) (not shown). figure). These entities are implemented in one or more physical or logical devices. For example, each slice may have an AMF, an SMF, and a UPF, respectively, or may share some or all.

In the wireless communication system 1, the terminal 10 can communicate with one or more base stations 20. For example, in FIG. 1, a terminal 10 can communicate with one base station 20 using carrier aggregation (CA) that integrates a plurality of cells C. FIG. The terminal 10 can also communicate with a plurality of base stations 20 by dual connectivity (DC) connecting to two cell groups each including one or more cells C. When two cell groups use different RATs, the DC may be called a Multi-RAT DC (MR-DC).

FIG. 2 is a diagram for explaining network slicing and network slicing. By network slicing, the entire or partial resources of the network including the radio access network (RAN) 2 composed of a plurality of base stations 20 and the core network 30 are virtually divided as network slices. The core network 30 and the base station 20 may be individually prepared for each network slice, or part or all of them may be shared between different network slices. Network slicing typically divides the core network 30 logically/virtually, but may divide the radio access network 2 physically/logically/virtually. For example, the base station 20 allocates (scheduling) radio resources to the terminal 10, and performs various functions related to layer 1 (physical layer), layer 2 (MAC layer, RLC layer, PDCP layer) and layer 3 (RRC layer). By performing processing for each slice, network slicing can be realized in the radio access network 2 .

In the example of FIG. 2, the core network 30 includes a core network (eMBB (enhanced Mobile Broadband)) 30-1 for high-capacity high-speed communication and a core network (URLLC (Ultra Reliable Low Latency Communication) 30-1 for low delay). 2 and a core network for IoT terminals (MIoT (massive IoT)) 30-3, which can be operated as slice 1, slice 2, and slice 3, respectively. indicates that Terminals having different service requirements, for example, a terminal 10-1 used as a game machine, a terminal 10-2 mounted on a vehicle and used as an IoT device, and a terminal 10-3 used as an IoT device, have respective service requirements. belong to slice 1, slice 2 and slice 3.

In this case, the communication performed by the terminal 10-1 is processed by the core network (eMBB) 30-1. Communication performed by the terminal 10-2 is processed by the core network (URLLC) 30-2. Communication performed by the terminal 10-3 is processed by a core network (MIoT) 30-3. By using network slices in this way, it becomes possible to perform communication processing suitable for the characteristics of the service required of the terminal 10 .

FIG. 3 is a diagram illustrating a conventional processing procedure when the terminal 10 is registered with the network. In FIG. 3, the radio access network 2 including at least one base station 20 and the core network 30 are collectively described as "network". It is also assumed that the core network 30 has previously known which base station 20 (cell) supports which network slice.

First, the state of the terminal 10 will be explained. The state of the terminal 10 includes an idle state, an inactive state, and a connected state (in-communication state). The idle state is a state in which the terminal 10 has not established an RRC connection with the base station 20, and is also called an RRC_IDLE state, an idle mode, or the like.

The terminal 10 in the idle state receives the system information of the cell C (step S10), and camps on the cell C selected by cell selection or reselection (step S11). "Camping (on) in cell C" may be rephrased as "being in cell C." It should be understood that the system information received by the terminal 10 means information broadcast from the network and is different from an RRC (Radio Resource Control) message that the network can individually notify to each terminal 10.

Cell selection is to select a cell C (also called a "suitable cell") that satisfies a predetermined criterion (Cell Selection Criteria).

Cell reselection is to discover (detect) and camp on a cell C (more suitable cell) that is more suitable than the cell C currently camped on according to a predetermined criterion (Cell Reselection Criteria). Cell reselection includes reselection of cell C with the same carrier frequency as cell C to camp on (intra-frequency cell reselection), reselection of cell C with a carrier frequency different from cell C to camp on. Selection (inter-frequency cell reselection), including reselection (inter-RAT cell reselection) of cell C on a carrier frequency of a different RAT than cell C to camp on.

Next, the terminal 10 transmits a signal called a random access preamble to the base station 20 using radio resources notified in advance by system information (step S12). The random access preamble is also called message 1 (Msg1). Upon receiving the random access preamble, the base station 20 transmits a random access response message (Random Access response) to the terminal 10 (step S13). The random access response message is also called message 2 (Msg2). Subsequently, the terminal 10 transmits an RRC message including an RRC setup request (RRC Setup Request) to the base station 20 (step S14). The RRC setup request message includes at least information indicating the reason for establishing RRC (Establishment Cause). The message containing the RRC setup request is also called message 3 (Msg3).

Subsequently, the base station 20 transmits an RRC message including RRC setup (RRC Setup) to the terminal 10 (step S15). The RRC message containing RRC setup is also called message 4 (Msg4). Subsequently, the terminal 10 transmits an RRC message including RRC setup complete (RRC Setup Complete) to the base station 20 (step S16). The RRC message containing the RRC setup complete is also called message 5 (Msg5). When the transmission of message 5 is completed, an RRC connection is established, and terminal 10 in the idle state transitions to the connected state.

When the terminal 10 wishes to register with a network slice, the terminal 10 sends a registration request (Registration Request) including an ID that uniquely identifies the network slice that requests registration to an RRC Setup Complete (RRC Setup Complete) message. and transmit it to the base station 20. A registration request (Registration Request) is notified as a NAS (Non-Access Stratum) message, which is an upper layer of the RRC layer. An ID that uniquely identifies a network slice is called S-NSSAI (Single Network Slice Selection Assistance Information). A list of multiple S-NSSAIs is called NSSAI (Network Slice Selection Assistance Information). Hereinafter, S-NSSAI will be described as including NSSAI.

When the registration request including S-NSSAI is notified by message 5, the base station 20 selects the core network 30 (AMF) for registering the terminal information, and sends the registration request to the selected core network 30. Request). The core network 30 (AMF) registers the requested network slice based on the network slice supported by the base station 20 (or cell) that received the registration request and the network slice supported by the core network 30. It determines whether or not it is possible to accept registration at the base station 20, and notifies the base station 20 of the determination result. The base station 20 includes information (Allowed NSSAI) or It includes information indicating that the requested S-NSSAI is not supported (Rejected NSSAI) and transmits it to the terminal 10 (step S17).

FIG. 4 is a diagram explaining the structure of the S-NSSAI defined in the 3GPP specifications. FIG. 4A shows the bit structure of the S-NSSAI. S-NSSAI is composed of SST (Slice/Service Type) indicating the type of network slice and SD (Slice Differentiator) which is information for distinguishing network slices belonging to the same SST. For example, SST may consist of 8 bits and SD may consist of 24 bits. Since SD is optional information, it does not necessarily have to be included in S-NSSAI. That is, S-NSSAI is an information bit consisting of 8 bits or 32 bits.

FIG. 4B is the definition of the SST Value. SST values = 1, 2, 3 and 4 indicate that the service types (or slice types) provided by the network slices are eMBB, URLLC, MIoT and V2X (Vehicle-to-Everything), respectively. It should be noted that the definition of the SST value will not be limited to that in FIG. 4B in the future, and new SST values may be added.

According to the conventional processing procedure described above, when the terminal 10 desires to be registered in a predetermined network slice, the terminal 10 executes the random access procedure in the cell camped on by cell selection or reselection, and registers in the network. Without processing, it is impossible to know whether a given network slice is supported or not. If the network does not support the network slice that the terminal 10 wishes to register, the random access procedure and the network registration process (that is, the process procedure of steps S12 to S17 in FIG. 3) will be wasted. .

Therefore, in the present embodiment, in the system information transmitted by each base station 20, slice information indicating network slices that can be provided in the cell C formed by each base station 20 and a network slice realization method (execution method) are provided. , provision method, support type, etc.), and the terminal 10, when selecting or reselecting a cell, uses an implementation method that the terminal 10 supports (provides), A cell (frequency corresponding to the cell) capable of providing network slices supported by the terminal 10 is preferentially camped on.

FIG. 5 is a diagram exemplifying the contents of slice information and slice additional information included in system information.
Slice information includes slice type information that indicates the service type (Slice/service type) of the slice, and a unique slice that is coded and assigned that uniquely indicates the correspondence relationship between the slice type information and slice additional information (described later). identification information, etc., may be included. The system information including slice information and slice additional information may be transmitted from the base station 20 as periodically scheduled system information, or system information transmitted in response to a request from the terminal 10 (on-demand system information). system information) may be transmitted from the base station 20.

Slice additional information is support function information indicating the support function of the terminal 10 required for realizing (executing) the slice (that is, the terminal capability information minimum required to satisfy the requirements of the service corresponding to the slice); In addition, if support for a predetermined frequency is required to realize a slice, frequency information representing the frequency or combination information of multiple frequencies, other additional information (for example, detailed content of support function information), etc. may be included. good. In other words, the slice additional information is an execution condition (requirement condition) for executing the slice.
"Packet duplication (2CC)" and "Packet duplication (4CC)" indicated in the support function information are techniques for realizing URLLC (slice) using a plurality of frequencies (cells). On the other hand, "IIoT enhancement" is a technology that implements URLLC (slice) using transmission priority control and the like in a single frequency (cell).

"Packet duplication (2CC)" and "Packet duplication (4CC)" are duplicated using 2 CCs (2 cells) and 4 CCs (4 cells) by using CA or DC, respectively. It means a technology to improve the arrival probability (reliability) of packets by transmitting the packets through different transmission routes.

Also, "X" and "Y" indicated in the frequency information indicate the band number to be used, and the band number specified by 3GPP is set. For example, if X is 1, band 1 is used, and if X is 40, band 40 is used. Also, for example, "CA#X" corresponding to "Packet duplication (2CC)" means performing carrier aggregation (CA) using two frequencies (two cells) in band X. . Similarly, "CA#X-Y" corresponding to "Packet duplication (4CC)" uses two frequencies in band X and two frequencies in band Y (that is, a total of four cells). "DC#XY", which means performing carrier aggregation (CA) using "Packet duplication (4CC)", has two frequencies in band X and frequencies in band Y. It means performing dual connectivity (DC) using two (that is, four cells in total).

<Hardware configuration>
FIG. 6 is a diagram showing an example of hardware configurations of the terminal 10 and the base station 20. As shown in FIG. The terminal 10 and the base station 20 have a processor 11, a memory 12, a storage device 13, a communication device 14 for wired or wireless communication, an input device 15 for receiving input operations, an output device 16 for outputting information, and an antenna 17.

The processor 11 is, for example, a CPU (Central Processing Unit) and controls the terminal 10 or the base station 20.

The memory 12 is composed of, for example, ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM) and/or RAM (Random Access Memory).

The storage device 13 is composed of storage such as HDD (Hard Disk Drive), SSD (Solid State Drive) and/or eMMC (embedded Multi Media Card), for example.

The communication device 14 is a device that communicates via a wired and/or wireless network, such as a network card or a communication module. Further, the communication device 14 may include an amplifier, an RF (Radio Frequency) device that performs processing related to radio signals, and a BB (BaseBand) device that performs baseband signal processing.

For example, the RF device generates a radio signal to be transmitted from the antenna 17 by performing D/A conversion, modulation, frequency conversion, power amplification, etc. on the digital baseband signal received from the BB device. Further, the RF device generates a digital baseband signal by performing frequency conversion, demodulation, A/D conversion, etc. on the radio signal received from the antenna 17, and transmits the digital baseband signal to the BB device. The BB device performs a process of converting a digital baseband signal into a packet and a process of converting the packet into a digital baseband signal.

The input device 15 is, for example, a keyboard, touch panel, mouse and/or microphone. The output device 16 is, for example, a display and/or a speaker.

<Functional block configuration>
(terminal)
FIG. 7 is a diagram showing a functional block configuration example of the terminal 10. As shown in FIG. Terminal 10 includes a storage unit 100 , a reception unit 101 , a transmission unit 102 , an acquisition unit 103 and a control unit 104 . Note that FIG. 6 shows functional blocks required in this embodiment. Storage unit 100 may be implemented using memory 12 and/or storage device 13 provided in terminal 10 . The receiving unit 101 and the transmitting unit 102 may be implemented by the communication device 14, for example, or may be implemented by the processor 11 executing a program stored in the storage device 13 in addition to the communication device 14. . Acquisition unit 103 and control unit 104 may be implemented by processor 11 of terminal 10 executing a program stored in storage device 13 . Also, the program can be stored in a storage medium. The storage medium storing the program may be a non-transitory computer readable medium. Non-temporary storage media are not particularly limited, but may be storage media such as USB memory or CD-ROM, for example.

The storage unit 100 stores, as terminal capability information, slice information indicating one or more network slices supported by the terminal 10 itself, slice additional information indicating a method of implementing the network slices supported by the terminal 10 itself, and the like.

The receiving unit 101 receives downlink signals from the base station 20 . The transmitting unit 102 generates an uplink (UP Link) signal and transmits it to the base station 20 . Also, in the present embodiment, the transmitting unit 102 utilizes an RRC message (eg, message 5 including RRC setup complete) instead of or in addition to S-NSSAI to implement (execute, Terminal 10 notifies base station 20 of the slices that terminal 10 can implement by transmitting to base station 20 one or more pieces of slice identification information indicating slices that can be supported.

The acquisition unit 103 acquires slice additional information indicating a network slice realization method together with slice information indicating a network slice that can be provided by a cell (see FIG. 5). "Network slices that can be provided by cells" include "network slices supported by cells", "network slices that can be registered in an area including cells", "network slices that can be provided by the base station 20 (or network)", It may be read as "a network slice supported by the base station 20 (or network)" or "a network slice that can be registered in an area including the base station 20 (or network)". Acquisition section 103 acquires slice information and slice additional information from the system information received from base station 20 .

Control unit 104 selects a cell to camp on (cell selection) or reselects (cell reselect). Specifically, first, based on the slice information and slice additional information acquired by the acquisition unit 103, the control unit 104 checks the network slice supported by each cell (or the carrier frequency of the cell) and the implementation method of the slice. do. Then, control section 104 refers to the terminal capability information stored in storage section 100 and determines whether or not own terminal 10 supports the checked slice and slice realization method.

Based on the check result, the control unit 104 identifies a cell that can provide a network slice by the implementation method supported by the terminal 10 . Then, the control unit 104 regards the specified cell as a suitable cell, and selects or reselects a cell to camp on from among the suitable cells.
As an example, the control unit 104 selects or reselects a cell by increasing the frequency priority (hereinafter referred to as frequency priority) of a cell that supports the checked slice and slice implementation method. Note that the frequency priority of the cell is notified as system information and set in the storage unit 100, SIM card, or the like as priority information.

8A and 8B are explanatory diagrams for explaining the operation of changing/not changing the frequency priority of cells.
As a premise, the terminal 10 supports at least a method of realizing "eMBB" (slice) and "URLLC" (slice). In addition, the terminal 10 supports at least frequency #0 (F#0), frequency #1 (F#1), and frequency #2 (F#2) as usable frequencies. When terminal 10 supports a function (CA and/or DC) that simultaneously uses frequencies F#1 and F#2 and at least supports packet duplication using frequencies F#1 and F#2 assume.

For example, as shown in FIG. 8A, when the slice that the terminal 10 preferentially (intentionally) attempts to use is URLLC (Intended Slice = URLLC), slice information and slice addition obtained from system information Based on the information, it was determined that "URLLC" (slicing) can be realized by packet duplication ("Packet duplication (2CC)") using multiple frequencies (F#1, #2) supported by terminal 10 In this case, the control unit 104 sets the priority of each frequency (F#1, #2) as (corresponding) frequency information related to the support function information "Packet duplication (2CC)" to the frequency (F#0 ), the frequency priority indicated in the priority information is changed so as to be higher than the priority of .

On the other hand, as shown in FIG. 8B , the slice that the terminal 10 preferentially (intentionally) tries to use is URLLC, and any frequency indicated by the frequency information related to the support function information “Packet duplication (2CC)” ( Here, when camped on F#1), the control unit 104 does not need to change the frequency priority indicated in the priority information.
After changing the frequency priority of the cell in this way, the control unit 104 can select or reselect the cell according to the changed frequency priority of the cell.

(base station)
FIG. 9 is a diagram showing an example of the functional block configuration of the base station 20. As shown in FIG. Base station 20 includes storage section 200 , receiving section 201 and transmitting section 202 . Note that FIG. 9 shows functional blocks required in this embodiment. Storage unit 200 may be implemented using memory 12 and/or storage device 13 provided in base station 20 . The receiving unit 201 and the transmitting unit 202 may be implemented by the communication device 14, for example, or may be implemented by the processor 11 executing a program stored in the storage device 13 in addition to the communication device 14. . Also, the program can be stored in a storage medium. The storage medium storing the program may be a computer-readable non-temporary storage medium. Non-temporary storage media are not particularly limited, but may be storage media such as USB memory or CD-ROM, for example.

The receiving unit 201 receives uplink signals from the terminal 10 . The transmitting unit 202 generates a downlink signal and transmits it to the terminal 10 . Also, the transmitting unit 202 transmits system information including slice information and slice additional information. In addition, the receiving unit 201 and the transmitting unit 202 perform random access procedures and RRC connection establishment processing with the terminal 10 (for example, reception of an RRC Setup Complete message containing desired slice information), and transmission and reception of other RRC messages. and perform the corresponding processing. Also, the receiving unit 201 and the transmitting unit 202 transmit and receive messages (NAS messages) to and from the core network 30 .

In addition, the transmission unit 202 transmits slice information indicating network slices that can be provided in a cell and slice additional information indicating a method of realizing network slices in the system information. Transmitter 202 includes, as system information, SIB1 (System Information Block Type1) containing information on serving cells, SIB2 (System Information Block Type2) containing cell reselection information, and SIB4 (System Information Block Type4) containing peripheral cell information. Slice information and slice additional information are transmitted using all or one of them. Further, the transmitting unit 202 may include the slice information and the additional slice information in separate system information and transmit them, or may transmit either of them as the on-demand system information. For example, the transmitting unit 202 may transmit the slice information as normal system information, and transmit the slice additional information as on-demand system information at any timing in response to a request from the terminal 10 . In addition, the receiving unit 201 selects or reselects a cell to camp on from among the cells that can provide network slices by the implementation method supported by the terminal 10, based on the slice information and the slice additional information for the terminal 10. to receive from the terminal 10 the information of the network slice that the terminal 10 uses. A base station 20 may support network slicing in multiple implementations in a single cell. The base station 20 may explicitly or implicitly notify the terminal 10 of which implementation method is prioritized in the system information. In the case of implicit notification, the base station 20 may notify the priority based on the setting order of slices set in the system information (for example, when the terminal 10 is notified in a list format, the list descending order (ascending order) is considered to have lower priority). The terminal 10 may select or reselect a cell according to the explicitly or implicitly notified priority.

<Processing procedure>
Next, the processing procedure performed by the wireless communication system 1 according to this embodiment will be specifically described.

FIG. 10 is a flowchart showing an example of a processing procedure when the terminal 10 selects or reselects a cell.

In step S100, the acquiring unit 103 searches for neighboring cells of the terminal 10 itself, receives system information including slice information and slice additional information in the detected cell, and receives slice information and slice additional information at camp-on. Get the information you need.

In step S101, when selecting or reselecting a cell, the control unit 104 determines whether or not there is an appropriate cell capable of providing a network slice by an implementation method supported by the terminal 10 itself, terminal capability information held by the terminal 10, The determination is made based on the obtained system information. As described above, the terminal capability information includes slice information indicating network slices supported by the terminal 10 itself, and additional slice information indicating a method of implementing the network slices supported by the terminal 10 itself. The terminal capability information may be stored in the storage unit 100 in advance, or may be stored in a SIM (Subscriber Identity Module). The control unit 104 proceeds to the processing procedure of step S102 if the cell is found, and proceeds to the processing procedure of step S103 if not found. Note that the "appropriate cell" in the procedure of step S101 may mean the cell C that satisfies a predetermined criterion (Cell Selection Criteria) when selecting a cell. In addition, when reselecting a cell, the "suitable cell" is a cell C (more suitable cell) that is found according to a predetermined criterion (Cell Reselection Criteria) and is more suitable than the currently camped-on cell C. It can mean.

The terminal 10 may be capable of supporting network slicing in multiple implementations. For example, it is assumed that the terminal 10 supports a slice whose slice/service type is 'URLLC' by a plurality of implementation methods such as 'Packet duplication (2CC)' and 'IIoT enhancement'.

In this case, the terminal 10 preferentially, for example, prefers a cell that supports "packet duplication (2CC)" over "IIoT enhancement" as a cell to camp on, according to a user's instruction or an operator's (PLMN) contract. You may make it select.

Further, in the processing procedure of step S100 and the processing procedure of step S101, after determining that the cell satisfies a predetermined criterion, the terminal 10 determines whether a network slice can be provided by a supported implementation method. can be Additionally, a determination may be made whether a supported implementation can provide a network slice regardless of whether it meets predetermined criteria. In addition, the terminal 10 determines whether the network slice can be provided by the supported implementation method only when the quality of the cell in which the terminal 10 is located (camped) or the measured cell quality is equal to or higher than a certain threshold. can be That is, if the serving cell or the measured cell quality is less than (or below) the threshold, the terminal 10 may apply a normal cell selection or cell reselection procedure that does not consider slice information. good. The base station 20 may notify the threshold associated with cell selection or cell reselection in system information for each slice as part of slice additional information.

In step S102, the control unit 104 of the terminal 10 camps on the cell discovered in step S101, and returns to the processing procedure of step S100 to search for a more suitable cell than the camped-on cell. do.

In step S103, when the control unit 104 of the terminal 10 ends the cell selection or reselection process (for example, when turning off the power of the terminal 10) (step S103-YES), the processing procedure shown in FIG. 10 ends. . If not finished (step S103-NO), the procedure returns to step S100.

As described above, according to the present embodiment, it is possible to select or reselect a cell in consideration of the implementation method of a network slice that a terminal attempts to use. As a result, the terminal can quickly and appropriately receive the network slice to be used.
Next, a plurality of modifications of the processing procedure of step S100 will be described. Modifications shown below can be combined arbitrarily.

(Modification 1)
Instead of changing the frequency priority of cells, the priority of cells may be changed.
For example, when the terminal 10 supports a plurality of slices and slice realization methods, when selecting or reselecting a cell, the terminal 10 selects the slice with the highest priority and the slice realization method. , may be selected as the cell to camp on. Note that the cell priority may be set in the storage unit 100, the SIM card, or the like as priority information.

(Modification 2)
Acquisition section 103 uses an RRC message (for example, RRC Reconfiguration, RRC Release, etc.) individually notified from base station 20 to each terminal 10 instead of broadcasted system information, thereby obtaining slice information related to neighboring cells in advance. and slice additional information. For example, slice information may be obtained from system information, while slice additional information may be obtained from an RRC message (RRC Release, etc.). In this case, the control section 104 may change the frequency priority of the cell based on the additional slice information included in the individually notified RRC message. When the slice information and the additional slice information are obtained from the system information, and the base station 20 notifies another slice information and additional slice information in the RRC message, the control unit 104 receives the other information notified in the RRC message. slice information and slice additional information may be preferentially used. Also, the base station 20 may set valid time for other slice information and slice additional information notified by the RRC message. When the valid time is set, the control unit 104 uses other slice information and slice additional information notified by the RRC message during the valid time, and slices from the system information of the serving cell after the valid time expires. Information and slice additional information may be reacquired and used.

In this way, by notifying each terminal 10 of slice additional information individually, it is possible to provide more appropriate slices in consideration of communication traffic and the like.

The slice information may be provided in a bitmap format in which bits corresponding to the slices to be supported are set, may be provided in a list format in which the slices to be supported are listed, or may be notified of the SST value. good. Also, the slice additional information may be provided in the form of a list in which the slice realization method is registered for each supported slice, for example (see FIG. 5).

(Modification 3)
Regarding slice additional information, the base station 20 considers the case where the target quality corresponding to a slice differs between uplink (UL) and downlink (DL), for example, and combines uplink frequency information and downlink frequency information. It may be set separately in the system information or RRC message.

For example, when the slice "URLLC" is realized by "Packet duplication (2CC)", frequency information such as "UL: CA#X1, CA#Y1" is set for the uplink (UL), while the downlink For (DL), frequency information such as "DL: CA#X2, CA#Y2" (X1≠X2, Y1≠Y2) can also be set.

Control unit 104, based on the slice additional information in which different frequency information is set for uplink and downlink, and the determination result as to whether the service using slices corresponds to uplink or downlink, the cell It is sufficient to change the frequency priority of .

(Modification 4)
The information amount of slice additional information may be reduced by linking frequency information related to a method of implementing network slices supported by the terminal 10 to the band combination information transmitted from the terminal 10 to the base station 20 . “Band combination information” is information indicating a combination of frequencies (bands) supported by the terminal 10 , and is transmitted to the base station 20 by being included in an RRC message such as a “UE Capability Information message”, for example.

For example, among a plurality of frequencies (bands) included in the band combination information, the terminal 10 uses bands (for example, bands “F#1” and “F#2”) corresponding to frequency information related to a network slice implementation method. etc.) and band combination, flag information (or SST) corresponding to the slice is added and transmitted to the base station 20 as a "UE Capability Information message". This makes it possible to efficiently reduce the amount of slice additional information to be transmitted from the terminal 10 to the base station 20 . Also, when the base station 20 notifies the frequency information as the slice additional information by the RRC message, the number corresponding to the band combination information transmitted from the terminal 10 is set instead of the frequency information, thereby reducing the amount of information. may For example, when the terminal 10 includes the band combination "CA#X1" at the n-th position in the band combination information list and transmits it, instead of notifying "CA#X1" as the frequency information, it notifies "n".

<Summary>
According to the embodiments described above, the terminal 10 camps on a cell capable of providing a network slice by a method supported by the terminal 10 itself, based on slice information and slice additional information included in system information and the like. made it This makes it possible to provide a technique that enables selection or reselection of cells in consideration of the implementation method of network slicing.

The embodiments described above are for facilitating understanding of the present invention, and are not for limiting interpretation of the present invention. Flowcharts, sequences, elements included in the embodiments, their arrangement, materials, conditions, shapes, sizes, and the like described in the embodiments are not limited to those illustrated and can be changed as appropriate. Moreover, it is possible to partially replace or combine the configurations shown in the modified examples and the like.

Reference Signs List 1 wireless communication system 10 terminal 11 processor 12 memory 13 storage device 14 communication device 15 input device 16 output device 17 antenna 20 base station 30 core Network 100 Storage unit 101 Reception unit 102 Transmission unit 103 Acquisition unit 104 Control unit 200 Storage unit 201 Reception unit 202 Transmission unit

Claims

a terminal,
an acquisition unit that acquires slice information indicating a network slice that can be provided by a cell and slice additional information indicating a method for realizing the network slice;
Control for selecting or reselecting a cell to camp on from among cells capable of providing the network slice, based on the slice information, the slice additional information, and the network slice implementation method supported by the terminal. Department and
terminal with
The slice information includes slice type information indicating a type of the network slice,
The slice additional information includes support function information indicating support functions of the terminal necessary for realizing the network slice,
A terminal according to claim 1 .
The slice additional information further includes frequency information indicating a combination of one or more frequencies associated with the support function information,
A terminal according to claim 2.
The control unit generates priority information indicating a frequency priority of a cell corresponding to the frequency information based on the slice information, the frequency information included in the slice additional information, and the frequencies supported by the terminal. Set,
Selecting or reselecting the cell based on the priority information;
A terminal according to claim 3.
A base station that communicates with a terminal,
a transmission unit that includes slice information indicating a network slice that can be provided by a cell and slice additional information indicating a method of realizing the network slice in system information and transmits the slice information;
For the terminal, based on the slice information, the slice additional information, and a network slice implementation method supported by the terminal, from among the cells that can provide the network slice, select a cell to camp on or a receiving unit that executes reselection and receives, from the terminal, identification information of a network slice that the terminal corresponding to the slice information attempts to use;
A base station with
The transmission unit includes the slice additional information in an RRC message that is different from the system information and individually transmits the terminal to the terminal.
A base station according to claim 5 .
A communication method performed by a terminal,
acquiring slice information indicating network slices that can be provided by a cell and slice additional information indicating a method of realizing the network slices;
A step of selecting or reselecting a cell to camp on from among cells capable of providing the network slice based on the slice information, the slice additional information, and a network slice implementation method supported by the terminal. When,
communication methods, including
to the computer,
acquiring slice information indicating network slices that can be provided by a cell and slice additional information indicating a method of realizing the network slices;
A step of selecting or reselecting a cell to camp on from cells capable of providing the network slice based on the slice information, the slice additional information, and the network slice implementation method supported by the computer. When,
program to run the