Cell reselection method, user equipment, system, program, and chipset

Abstract

To provide a slice-based cell reselection method corresponding to a network slice.SOLUTION: In a mobile communication system, a cell reselection method used in a user apparatus includes a step of performing slice-based cell reselection in response to the user apparatus receiving, from a network node, slice-specific cell reselection information indicating a cell reselection priority for each slice group and for each frequency, and a step of determining, based on whether or not the slice-based cell reselection to which the slice-specific cell reselection information is applied is being performed, whether or not it is possible to apply highest priority processing in which a frequency or a cell that provides a predetermined function different from the slice-based cell reselection is regarded as having a highest priority for cell reselection.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates to a cell reselection method for use in a mobile communication system. [Background technology]

[0002] The 3GPP (3rd Generation Partnership Project) defines technical specifications for slice-based cell reselection functions that support network slices (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP Technical Specification: TS 38.304 V17.1.0 Summary of the Invention

[0004] A cell reselection method according to a first aspect is a cell reselection method used in a user equipment, and includes the steps of: performing slice-based cell reselection in response to the user equipment receiving slice-specific cell reselection information indicating cell reselection priority for each slice group and each frequency from a network node; and determining whether to apply a highest priority process that considers a frequency or cell that provides a predetermined function different from that of the slice-based cell reselection as having the highest priority for cell reselection, based on whether the slice-based cell reselection is being performed using the slice-specific cell reselection information.

[0005] A cell reselection method according to a second aspect is a cell reselection method used in a user equipment, and includes the steps of: performing slice-based cell reselection applying slice-specific cell reselection information indicating cell reselection priority for each slice group and each frequency, in response to the user equipment receiving the slice-specific cell reselection information from a network node; and acquiring from the network node or a NAS (Non-Access Stratum) configuration information for setting whether or not to apply a highest priority process in which a frequency or cell that provides a predetermined function different from the slice-based cell reselection is considered to have the highest priority for cell reselection.

[0006] A cell reselection method according to a third aspect is a cell reselection method used in a user equipment, and includes the steps of: transmitting preference information indicating the user equipment's preference for whether slice-based cell reselection or a predetermined function different from the slice-based cell reselection should be prioritized in cell reselection to a network; and controlling the slice-based cell reselection and a highest priority process in which a frequency or a cell that provides the predetermined function is considered to have the highest priority for cell reselection in accordance with configuration information received from the network based on the preference information.

[0007] A cell reselection method according to a fourth aspect is a cell reselection method used in a user device, and includes the steps of: acquiring priority slice group information indicating a priority slice group from a NAS (Non-Access Stratum); checking whether information indicating a predetermined function different from the slice-based cell reselection is included in any of the slice groups indicated by the priority slice group information; and, in response to the information indicating the predetermined function being included in any of the slice groups, regarding the slice group including the information indicating the predetermined function or the frequency providing the predetermined function as having the highest priority in cell reselection.

[0008] A cell reselection method according to a fifth aspect is a cell reselection method used in a user device, and includes the steps of: acquiring priority slice group information indicating a priority slice group from a NAS (Non-Access Stratum); executing a predetermined function different from the slice-based cell reselection; receiving slice-specific cell reselection information indicating cell reselection priority for each slice group and each frequency from a network node; and regarding the frequency providing the predetermined function as the highest priority in cell reselection, among the frequencies for which the cell reselection priority is set in the slice-specific cell reselection information for the highest priority slice group indicated by the priority slice group information. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating a configuration of a mobile communication system according to an embodiment. [Figure 2] 1 is a diagram illustrating a configuration of a UE (user equipment) according to an embodiment. [Figure 3] A diagram showing the configuration of a gNB (base station) according to an embodiment. [Figure 4] FIG. 10 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data. [Figure 5] FIG. 1 is a diagram showing the configuration of a protocol stack of a radio interface of a control plane that handles signaling (control signals). [Figure 6] FIG. 1 is a diagram illustrating a general cell reselection procedure. [Figure 7] FIG. 1 illustrates a general flow diagram of a general cell reselection procedure. [Figure 8] FIG. 1 illustrates an example of network slicing. [Figure 9] FIG. 1 is a diagram for explaining an overview of slice-based cell reselection. [Figure 10] A figure showing an example of slice-specific cell reselection information. [Figure 11]FIG. 10 is a diagram illustrating an example of the operation of a UE according to a first operation pattern. [Figure 12] FIG. 10 is a diagram illustrating an example of operation of a mobile communication system according to a second operation pattern. [Figure 13] FIG. 10 is a diagram illustrating an example of operation of a mobile communication system according to a third operation pattern. [Figure 14] FIG. 10 is a diagram illustrating an example of UE operation according to a fourth operation pattern. [Figure 15] FIG. 10 is a diagram illustrating an example of UE operation according to a fifth operation pattern. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] (1) System configuration First, the configuration of a mobile communication system 1 according to an embodiment will be described. FIG. 1 is a diagram showing the configuration of the 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 taken as an example, but the mobile communication system may also be at least partially applied to an LTE (Long Term Evolution) system. The mobile communication system may also be at least partially applied to a sixth generation (6G) system.

[0012] 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. The 5GC 20 may be simply referred to as the core network (CN) 20. The RAN 10 and the CN 20 constitute the network of the mobile communication system 1.

[0013] The UE 100 is a mobile wireless communication device. The UE 100 may be any device used by a user. For example, the UE 100 may be a mobile phone terminal (including a smartphone) and / or a tablet terminal, a laptop PC, a communication module (including 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).

[0014] The NG-RAN 10 includes a base station (referred to as "gNB" in the 5G system) 200. 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 that performs wireless communication with a UE 100. One cell belongs to one carrier frequency (hereinafter simply referred to as "frequency").

[0015] In addition, gNBs can also connect to the Evolved Packet Core (EPC), which is the LTE core network. LTE base stations can also connect to 5GC. LTE base stations and gNBs can also be connected via a base station-to-base station interface.

[0016] The 5GC20 includes an Access and Mobility Management Function (AMF) and a User Plane Function (UPF) 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 UPF are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network.

[0017] 2 is a diagram showing the configuration of a UE 100 (user equipment) according to the embodiment. The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit that performs wireless communication with the gNB 200.

[0018] 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.

[0019] 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.

[0020] The control unit 130 performs various controls and processes in the UE 100. Such processes include processes of each layer described below. The operations of the UE 100 described above and below may be operations under the control of the control unit 230. 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.

[0021] 3 is a diagram showing the configuration of a gNB 200 (base station) according to an embodiment. The gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240. The transmitter 210 and the receiver 220 constitute a wireless communication unit that performs wireless communication with the UE 100. The backhaul communication unit 240 constitutes a network communication unit that performs communication with the CN 20.

[0022] The transmission unit 210 performs various transmissions under the control of the control unit 230. The transmission 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.

[0023] 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.

[0024] The control unit 230 performs various controls and processes in the gNB 200. Such processes include processes for each layer, which will be described later. The operations of the gNB 200 described above and below may be operations under the control of the control unit 230. 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 the 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, etc. The CPU executes programs stored in the memory to perform various processes.

[0025] The backhaul communication unit 240 is connected to neighboring 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. Note that the gNB 200 may be configured (i.e., functionally divided) with a CU (Central Unit) and a DU (Distributed Unit), and both units may be connected via an F1 interface, which is a fronthaul interface.

[0026] FIG. 4 is a diagram showing the configuration of a protocol stack of a radio interface of a user plane that handles data.

[0027] The user plane radio 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.

[0028] 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 CRC parity bits scrambled by the RNTI added.

[0029] 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 UE100 and the MAC layer of gNB200 via transport channels. The MAC layer of gNB200 includes a scheduler, which determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to UE100.

[0030] The RLC layer transmits data to the RLC layer on the receiving side 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 logical channels.

[0031] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0032] The SDAP layer maps IP flows, which are the units for Quality of Service (QoS) control by the core network, to radio bearers, which are the units for QoS control by the Access Stratum (AS). Note that if the RAN is connected to the EPC, SDAP is not necessary.

[0033] 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).

[0034] The protocol stack of the radio interface of the control plane has a Radio Resource Control (RRC) layer and a Non-Access Stratum (NAS) layer instead of the SDAP layer shown in FIG.

[0035] 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 in accordance with 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.

[0036] The NAS layer (also simply referred to as "NAS") located above the RRC layer performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the AMF 300A. Note that the UE 100 has an application layer and the like in addition to the radio interface protocol. Also, the layer below the NAS layer is referred to as the AS layer (also simply referred to as "AS").

[0037] (2) Slice-based cell reselection Next, slice-based cell reselection according to the embodiment will be described.

[0038] (2.1) General cell reselection procedure FIG. 6 is a diagram for explaining a general cell reselection procedure. UE 100 in an RRC idle state or an RRC inactive state performs a cell reselection procedure to transition from a current serving cell (cell #1) to a neighboring cell (any of cells #2 to #4) as it moves. Specifically, UE 100 identifies a neighboring cell on which it should camp by the cell reselection procedure, and reselects the identified neighboring cell. A case in which the current serving cell and the neighboring cell have the same frequency (carrier frequency) is called intra-frequency, and a case in which the current serving cell and the neighboring cell have different frequencies (carrier frequencies) is called inter-frequency. The current serving cell and the neighboring cell may be managed by the same gNB 200. The current serving cell and the neighboring cell may be managed by different gNBs 200.

[0039] FIG. 7 is a diagram showing a general flow of a general cell reselection procedure.

[0040] In step S10, the UE 100 performs a frequency prioritization process based on a priority (also referred to as an "absolute priority" or a "cell reselection priority") for each frequency specified by the gNB 200, for example, by a system information block (SIB) or an RRC release message. Specifically, the UE 100 manages the frequency priority specified by the gNB 200 for each frequency.

[0041] In step S20, UE 100 performs a measurement process to measure radio quality for each of the serving cell and the neighboring cell. UE 100 measures the received power and received quality of reference signals transmitted by each of the serving cell and the neighboring cell, specifically, CD-SSB (Cell Defining-Synchronization Signal and PBCH block). For example, UE 100 always measures radio quality for frequencies having a higher priority than the frequency priority of the current serving cell, and for frequencies having a priority equal to or lower than the frequency priority of the current serving cell, UE 100 measures the radio quality of the frequency having the same priority or lower priority when the radio quality of the current serving cell falls below a predetermined quality.

[0042] In step S30, UE 100 performs a cell reselection process to reselect a cell on which UE 100 will camp based on the measurement result in step S20. For example, if the frequency priority of a neighboring cell is higher than the priority of a current serving cell and the neighboring cell satisfies a predetermined quality standard (i.e., a minimum required quality standard) for a predetermined period, UE 100 may perform cell reselection to the neighboring cell. If the frequency priority of the neighboring cell is the same as the priority of the current serving cell, UE 100 may rank the radio qualities of the neighboring cells and perform cell reselection to the neighboring cell having a higher rank than the rank of the current serving cell for a predetermined period. If the frequency priority of the neighboring cell is lower than the priority of the current serving cell and the radio quality of the current serving cell is lower than a certain threshold and the radio quality of the neighboring cell is higher than another threshold, UE 100 may perform cell reselection to the neighboring cell.

[0043] (2.2) Network Slicing Network slicing is a technology that creates multiple virtual networks by virtually dividing a physical network constructed by a carrier (for example, a network consisting of NG-RAN10 and 5GC20). Each virtual network is called a network slice. In the following, a network slice may be simply referred to as a "slice."

[0044] Network slicing allows telecommunications operators to create slices that meet the service requirements of different service types, such as eMBB (Enhanced Mobile Broadband), URLLC (Ultra-Reliable and Low Latency Communications), and mMTC (massive Machine Type Communications), thereby optimizing network resources.

[0045] FIG. 8 is a diagram illustrating an example of network slicing.

[0046] Three slices (slice #1 to slice #3) are configured on a network 50 configured with an NG-RAN 10 and a 5GC 20. Slice #1 is associated with a service type called eMBB, slice #2 is associated with a service type called URLLC, and slice #3 is associated with a service type called mMTC. Note that three or more slices may be configured on the network 50. One service type may be associated with multiple slices.

[0047] Each slice is provided with a slice identifier that identifies the slice. An example of a slice identifier is S-NSSAI (Single Network Slicing Selection Assistance Information). S-NSSAI includes an 8-bit SST (slice / service type). S-NSSAI may further include a 24-bit SD (slice differentiator). SST is information indicating the service type to which the slice is associated. SD is information for differentiating multiple slices associated with the same service type. Information including multiple S-NSSAIs is called NSSAI (Network Slice Selection Assistance Information).

[0048] One or more slices may be grouped to form a slice group. A slice group is a group containing one or more slices, and a slice group identifier is assigned to the slice group. Such a slice group is called an NSAG (Network Slice AS Group).

[0049] (2.3) Overview of slice-based cell reselection FIG. 9 is a diagram for explaining an overview of slice-based cell reselection.

[0050] The gNB 200 transmits slice-specific cell reselection information to the UE 100 (AS) in an SIB16 and / or an RRC Release message specified by RRC. The slice-specific cell reselection information may include a reselection priority for each frequency and each NSAG, and a list of cells that support or do not support the slice of the NSAG. In the UE 100, the NAS provides the AS with preferred NSAG information (also referred to as "preferred slice group information") that includes the NSAG and its priority (priority to be considered during cell reselection).

[0051] If UE100 supports slice-based cell reselection and slice-specific cell reselection information is provided to UE100 (AS) from gNB200, UE100 uses the slice-specific cell reselection information. If slice-specific cell reselection information is not provided by gNB200 for any NSAG that the AS has obtained from the NAS in UE100 and is not taken into account during cell reselection, UE100 uses general cell reselection information that is not slice-specific.

[0052] The slice-specific cell reselection information includes information indicating the correspondence between NSAGs, frequencies, and cell reselection priorities. For example, the slice-specific cell reselection information indicates, for each NSAG, the frequency (one or more frequencies) that supports the NSAG and the cell reselection priority (also referred to as "slice-specific cell reselection priority") assigned to each frequency. An example of the slice-specific cell reselection information is shown in Fig. 10. The number indicated by "#" in Fig. 10 may be an identifier of the NSAG.

[0053] In the example shown in Fig. 10, three frequencies F1, F2, and F4 are associated with NSAG#1 as frequencies supporting NSAG#1. Of these three frequencies, the slice-specific cell reselection priority of F1 is "6," the slice-specific cell reselection priority of F2 is "4," and the slice-specific cell reselection priority of F4 is "2." In the example of Fig. 10, the slice-specific cell reselection priority is any one of 0 to 7, and the larger the number, the higher the priority.

[0054] Furthermore, three frequencies F1, F2, and F3 are associated with NSAG#2 as frequencies that support NSAG#2. Of these three frequencies, the slice-specific cell reselection priority of F1 is "0," the slice-specific cell reselection priority of F2 is "5," and the slice-specific cell reselection priority of F3 is "7."

[0055] Furthermore, three frequencies, F1, F3, and F4, are associated with NSAG#3 as frequencies supporting NSAG#3. Of these three frequencies, the slice-specific cell reselection priority of F1 is "3," the slice-specific cell reselection priority of F3 is "7," and the slice-specific cell reselection priority of F4 is "2."

[0056] (3) Highest priority processing in cell reselection Next, the highest priority process in cell reselection according to the embodiment will be described.

[0057] The UE 100 performs a highest priority process in which a frequency or a cell that provides a predetermined function different from slice-based cell reselection is considered to be the highest priority for cell reselection. The highest priority may be higher than the cell reselection priorities (also referred to as "network-configured priorities") 0 to 7 that can be configured by the network for the UE 100.

[0058] For example, the predetermined features to which the highest priority processing is applied include Multicast / Broadcast Services (MBS), sidelink communication, and High Speed ​​Dedicated Network (HSDN). In the embodiment, the UE 100 supports at least one feature among the MBS, sidelink communication, and HSDN. Note that the sidelink communication may include sidelink discovery.

[0059] A UE 100 in an RRC idle state or an RRC inactive state that supports MBS applies the normal cell reselection rules with the following modifications. Specifically, a UE 100 that is receiving or interested in receiving MBS broadcast services via Point-to-Multipoint (PTM) is permitted to give the highest priority (higher than other network-configured priorities) to a frequency that provides these MBS broadcast services when it can receive these MBS broadcast services only by camping on that frequency. If an MBS broadcast service that the UE 100 is interested in becomes unavailable (after the session ends) or if the UE 100 is no longer interested in receiving the broadcast service, the UE 100 no longer prioritizes that frequency. Also, a UE 100 that is receiving or interested in receiving MBS broadcast services via PTM is permitted to give the lowest priority (lower than other network-configured priorities) to a frequency on which it cannot receive these MBS broadcast services.

[0060] A UE 100 that supports sidelink communication and is interested in V2X services may consider whether NR sidelink communication and / or V2X sidelink communication are supported by the cell when performing cell reselection in RRC idle or RRC inactive state. The UE 100 may consider the following carrier frequencies as the highest priority (higher than the priorities of other network settings): If configured to perform both NR sidelink and V2X sidelink communications, the frequency that provides both NR sidelink and V2X sidelink communications; If configured to perform only NR sidelink communication, the frequency that provides the NR sidelink communication settings, The frequency that provides the V2X sidelink communication settings when configured to perform only V2X sidelink communication.

[0061] A UE 100 that supports HSDN and is in a high-speed moving state while in an RRC idle state or an RRC inactive state always considers an HSDN cell to be the highest priority (higher than the priorities of other network settings), while a UE 100 that is not in a high-speed moving state always considers an HSDN cell to be the lowest priority (lower than the priorities of other network settings).

[0062] (4) Operation according to the embodiment As described above, in slice-based cell reselection, preferred slice group information (NSAG priority) is set in the AS of UE 100 from the NAS (from another perspective, AMF 300A), and slice-specific cell reselection priority is set from gNB 200. The AS of UE 100 performs slice-based cell reselection by applying the slice-specific cell reselection priority corresponding to the preferred NSAG as the cell reselection priority.

[0063] Meanwhile, for each function (service) of the sidelink, HSDN, and MBS, the UE 100 can perform a highest priority process in which the frequency providing the corresponding function (service) is considered to have the highest priority depending on various conditions. Such a highest priority process may conflict with the cell reselection priority determined by slice-based cell reselection. For example, if the UE 100 considers the MBS frequency to have the highest priority, the UE 100 may perform cell reselection using a cell reselection priority that is different from the slice-specific cell reselection priority.

[0064] The first to fifth operation patterns according to the embodiment will be described below. The UE 100 is assumed to be in an RRC idle state or an RRC inactive state except when communicating dedicated signaling (e.g., an RRC Release message, an RRC Reconfiguration message) with the network. Of the first to fifth operation patterns, any one of the operation patterns may be implemented alone, or two or more operation patterns may be implemented in combination.

[0065] (4.1) First operation pattern In a first operation pattern according to the embodiment, the UE 100 (AS) performs slice-based cell reselection in response to receiving slice-specific cell reselection information indicating cell reselection priority for each NSAG and each frequency from the gNB 200. Based on whether slice-based cell reselection is being performed to which the slice-specific cell reselection information is applied, the UE 100 (AS) determines whether to apply a highest priority process that considers a frequency or a cell that provides a predetermined function (e.g., a sidelink, an HSDN, or an MBS) as having the highest priority for cell reselection.

[0066] Specifically, UE100 (AS) is not permitted to regard any frequency as the highest priority when applying the slice-specific cell reselection priority included in the slice-specific cell reselection information provided by gNB200. In other words, when UE100 (AS) applies the slice-specific cell reselection priority included in the slice-specific cell reselection information provided by gNB200, the highest priority process is disabled (i.e., prohibited).

[0067] The UE 100 (AS) acquires prioritized NSAG information indicating a prioritized NSAG from the NAS. Even if the UE 100 (AS) acquires the prioritized NSAG information from the NAS, if the UE 100 (AS) has not received slice-specific cell reselection information (slice-specific cell reselection priority) from the gNB 200, the UE 100 (AS) may determine that the highest priority process can be applied (i.e., enabled) and apply the highest priority process. If the UE 100 (AS) has not received slice-specific cell reselection information (slice-specific cell reselection priority) from the gNB 200, the UE 100 (AS) cannot perform slice-based cell reselection. Therefore, even if the prioritized NSAG information is set in the AS from the NAS, if the UE 100 (AS) has not received slice-specific cell reselection information (slice-specific cell reselection priority) from the gNB 200, the highest priority process can be applied. This makes it easier for the UE 100 to use desired functions through the highest priority process. Furthermore, when UE100 (AS) has not acquired preferred NSAG information from the NAS, it may determine that the highest priority process can be applied (i.e., enabled) and apply the highest priority process even if slice-specific cell reselection information (slice-specific cell reselection priority) has been received from the gNB200. When preferred NSAG information has not been acquired from the NAS, UE100 (AS) cannot perform slice-based cell reselection. Therefore, when preferred NSAG information has not been set in the AS from the NAS, the highest priority process can be applied even if UE100 (AS) has received slice-specific cell reselection information (slice-specific cell reselection priority) from the gNB200.

[0068] The highest priority process for this operation pattern may be enabled or disabled for all functions of sidelink, HSDN, and MBS (i.e., common enablement or disablement), or may be enabled or disabled for each function separately (i.e., function-specific enablement or disablement).

[0069] FIG. 11 is a diagram showing an example of operation of UE 100 according to the first operation pattern.

[0070] In step S101, an NSAG priority is set in the UE 100 (AS) from the NAS (AMF 300A). A slice-specific cell reselection priority may be set in the UE 100 from the gNB 200. By acquiring the NSAG priority from the NAS (AMF 300A) and the slice-specific cell reselection priority from the gNB 200, the UE 100 (AS) becomes capable of performing slice-based cell reselection.

[0071] In step S102, the UE 100 (AS) is in a state where the highest priority process can be performed by a predetermined function. For example, the UE 100 (AS) is in one of the following states: Sidelink (V2X sidelink / NR sidelink): Sidelink communication is established or there is an interest in sidelink communication. HSDN: The UE100 moves at high speed. ·MBS: Interested in receiving MBS sessions.

[0072] That is, in step S102, the UE 100 is in a state where it may regard a particular frequency or a particular cell as having the highest priority.

[0073] In step S103, the UE 100 (AS) checks whether the slice-specific cell reselection priority specified in the slice-based cell reselection is applied to the current cell reselection priority. That is, the UE 100 (AS) checks whether slice-based cell reselection (cell reselection associated with slice-based cell reselection) is being executed. Alternatively, the UE 100 (AS) may check whether it has prioritized NSAG information (that is, whether prioritized NSAG information has been set to the UE 100 (NAS) from the AMF 300A).

[0074] If the result of step S103 is YES, in step S104, the UE 100 (AS) does not regard the specific frequency or the specific cell as the highest priority in step S102, but applies (adopts) the slice-specific cell reselection priority in slice-based cell reselection to perform cell reselection. That is, the UE 100 (AS) does not perform the highest priority processing by a predetermined function.

[0075] On the other hand, if the result of step S103 is NO, in step S105, the UE 100 (AS) adopts the highest priority process and performs cell reselection by regarding the specific frequency or the specific cell in step S102 as the highest priority. That is, the UE 100 (AS) performs the highest priority process using a predetermined function.

[0076] In this operation pattern, it may be considered whether a predetermined cell whose radio quality satisfies a predetermined criterion supports prioritized NSAG. The predetermined cell may be a cell (serving cell) on which UE 100 is camped and / or a candidate cell (for example, the highest ranked cell). UE 100 (AS) may determine that the highest priority processing is applicable when a predetermined cell whose radio quality satisfies a predetermined criterion does not support prioritized NSAG. That is, if the highest ranked cell (which may be the cell on which UE 100 is currently camped) does not support a desired slice (NSAG with a high priority by NAS), UE 100 (AS) may consider a frequency or cell that provides a predetermined function as the highest priority. In this case, UE 100 (AS) may perform frequency prioritization processing (priority handling) again.

[0077] (4.2) Second movement pattern In the second operation pattern of the embodiment, gNB200 can set to UE100 whether or not to allow highest priority processing using a specified function (i.e., whether or not to prioritize highest priority processing using a specified function over slice-specific cell reselection priority).

[0078] In this operation pattern, the UE 100 (AS) performs slice-based cell reselection applying the slice-specific cell reselection information in response to receiving slice-specific cell reselection information indicating cell reselection priority (slice-specific cell reselection priority) for each NSAG and each frequency from the gNB 200. The UE 100 (AS) acquires, from the gNB 200 or NAS (from another perspective, the AMF 300A), configuration information for setting whether to apply highest-priority processing in which a frequency or a cell providing a predetermined function different from that of slice-based cell reselection is considered to have the highest priority for cell reselection. This allows the UE 100 (AS) to appropriately perform slice-based cell reselection and / or highest-priority processing under the management of the network.

[0079] The predetermined function includes a plurality of functions (for example, a sidelink, an HSDN, and an MBS). The configuration information may be information for setting whether or not to apply the highest priority process for each function. That is, the gNB 200 (or the AMF 300A) may set (notify) to the UE 100 whether or not to allow the highest priority process for each of the MBS / HSDN / sidelink.

[0080] The configuration information may be information for setting which of slice-based cell reselection and highest priority processing is to be prioritized in cell reselection. The configuration information may be information for setting priorities in cell reselection for slice-based cell reselection and each of a plurality of functions (e.g., sidelink, HSDN, and MBS) included in the predetermined functions.

[0081] FIG. 12 is a diagram showing an example of operation of the mobile communication system 1 according to the second operation pattern.

[0082] In step S201, the gNB 200 transmits configuration information indicating whether or not to permit processing in which the cell reselection priority is regarded as the highest priority to the UE 100 (AS). The UE 100 (AS) receives the configuration information. Here, the gNB 200 may transmit the configuration information by including it in an SIB, an RRC Release message, an RRC Reconfiguration message, or a newly defined message.

[0083] Alternatively, in step S201, the AMF 300A may transmit, to the UE 100 (NAS), by NAS signaling, configuration information indicating whether or not to permit processing in which the cell reselection priority is regarded as the highest priority. In the UE 100, the NAS may notify the AS of the configuration information.

[0084] The setting information includes at least one of the following information (a1) to (c1):

[0085] (a1) Information indicating whether or not to allow the highest priority processing: The information may be information on whether to allow application of the highest priority (i.e., highest priority processing by a predetermined function) to the cell reselection priority. The information may be information on whether to give priority to the slice-specific cell reselection priority over the highest priority processing. The information may be information on whether to allow application of the highest priority when the slice-specific cell reselection priority (or the NSAG priority by the NAS) is set.

[0086] (b1) Information indicating whether or not to allow the highest priority processing for each function: The information may be, for example, information that sets whether or not to allow the highest priority processing for each of MBS / HSDN / V2X sidelink / NR sidelink.

[0087] (c1) Information indicating the priority (priority) of each function: The information may be information that sets a priority for each of MBS / HSDN / V2X sidelink / NR sidelink / slice-based cell reselection. Here, slice-based cell reselection may further be information that sets a priority for each NSAG. For example, the information may indicate that NSAG#1 has a higher priority than MBS, but NSAG#2 has a lower priority than MBS. Slice-based cell reselection may further be information that sets a priority for each slice. For example, the information may indicate that NSSAI#1 has a higher priority than MBS, but NSSAI#2 has a lower priority than MBS. Note that the concept of priority in the NSAG one level above the NSAG to which the NSSAI belongs may be applied (reused) to the NSAG to which the NSSAI belongs.

[0088] The information may be information that sets whether to prioritize each of MBS / HSDN / V2X sidelink / NR sidelink for slice-based cell reselection, or information that sets whether to prioritize slice-based cell reselection over other functions.

[0089] In step S202, the UE 100 (AS) performs cell reselection control based on the setting information received in step S201.

[0090] For example, when UE100 (AS) sets the priority of MBS higher than slice-based cell reselection and regards the MBS frequency as the highest priority, the highest priority is regarded as a higher priority than the cell reselection priority (0 to 7) in slice-based cell reselection.

[0091] Furthermore, for example, when the priority of the V2X sidelink is set lower than that of slice-based cell reselection, when UE100 (AS) regards the V2X sidelink frequency as the highest priority, the highest priority is regarded as a priority lower than the cell reselection priority (0 to 7) in slice-based cell reselection.

[0092] Furthermore, for example, if the cell reselection priority for a frequency in slice-based cell reselection is 5, the highest priority for a V2X sidelink frequency is considered to be 4.

[0093] (4.3) Third movement pattern In the second operation pattern described above, it is assumed that the gNB200 and / or AMF300A are aware in advance of the functions (user preferences) that the UE100 wants to prioritize, but it is also assumed that such an assumption does not hold. There is a concern that the gNB200 and the AMF300A do not know, for example, whether it is better to prioritize NSAG (i.e., a function that uses slices such as URLLC) or MBS, which is better in terms of user experience. Therefore, the gNB200 and / or AMF300A may make inappropriate settings for the UE100, which may cause problems such as the user being unable to access functions that they really want to prioritize.

[0094] In this operation pattern, the UE 100 transmits preference information indicating the UE 100's preference for which of slice-based cell reselection and a predetermined function (highest priority processing) to prioritize in cell reselection to the network (gNB 200 or AMF 300A). The UE 100 (AS) controls the slice-based cell reselection and the highest priority processing in accordance with configuration information received from the network based on the preference information. Note that this operation pattern may be an operation performed prior to the operation of the above-mentioned second operation pattern. The preference information may be information indicating a priority preference in cell reselection for slice-based cell reselection and each of a plurality of functions (e.g., MBS / HSDN / V2X sidelink / NR sidelink).

[0095] FIG. 13 is a diagram showing an example of operation of the mobile communication system 1 according to the third operation pattern.

[0096] In step S301, the UE 100 (AS) in an RRC connected state transmits preference information indicating a preference for the priority of a function to the gNB 200. The UE 100 (AS) may transmit the preference information by including it in an RRC message, for example, a UE AS Assistance Information message, an MBS Interest Indication message, or a newly defined message. Alternatively, in step S301, the UE 100 (NAS) may transmit the preference information to the AMF 300A by NAS signaling.

[0097] The preference information includes at least one of the following information (a2) to (c2):

[0098] (a) Information indicating the priority of each function: The information may be, for example, a priority for each of MBS / HSDN / V2X sidelink / NR sidelink / slice-based cell reselection. Note that slice-based cell reselection may be regarded as a slice-based cell reselection function or as a function assigned to each slice configured in slice-based cell reselection.

[0099] Slice-based cell reselection may also be performed for each NSAG. For example, information may be provided that NSAG#1 has a higher priority than MBS, but NSAG#2 has a lower priority than MBS. Alternatively, information may be provided that NSAG#1 may be given the highest priority, but NSAG#2 is not allowed to be given the highest priority.

[0100] Slice-based cell reselection may also be performed for each slice. For example, information may be provided that NSSAI#1 has a higher priority than MBS, but NSSAI#2 has a lower priority than MBS. For the NSAG to which the NSSAI belongs, the priority concept of the NSAG one level above the NSAG may be applied (reused).

[0101] For example, when a slice for V2X (= a slice whose slice type is V2X) is set to be prioritized, a process may be performed in which a frequency that provides a V2X function is considered to have the highest priority (may be considered to be permitted). Additionally, when MBS and / or HSDN, etc. are defined as slice types, a frequency that provides a function designated by the slice type may be similarly considered to have the highest priority. In other words, depending on the slice type and the priority of each slice, a frequency that provides an associated function may be permitted to be considered to have the highest priority.

[0102] (b2) Information indicating whether you want to perform the highest priority processing for each function: The information may be, for example, information indicating a preference as to whether or not to perform highest priority processing for each of MBS / HSDN / V2X sidelink / NR sidelink.

[0103] (c2) Information indicating the priority (priority) of each function: The information may be information indicating priority preferences for each MBS / HSDN / V2X sidelink / NR sidelink / slice-based cell reselection.

[0104] In the UE 100, priority information for each function may be notified to the AS from an upper layer (application or NAS).

[0105] The priority information for each function may be notified from the AMF 300A to the UE 100 (NAS). In the UE 100, the priority information notified from the NAS to the AS may be notified from the AS to the gNB 200.

[0106] The gNB 200 that has received the preference information in step S301 may store the preference information as a UE context. The gNB 200 may transmit a response (setting) indicating whether or not to permit the preference information to the UE 100. For example, when permission is set by an RRC Reconfiguration message or an RRC Release message, the UE 100 (AS) may transition to an RRC idle state or an RRC inactive state, and then perform a process of specifying a cell reselection priority in accordance with the permission information.

[0107] In step S302, the gNB 200 may perform cell reselection-related configuration for the UE 100 (AS) based on the preference information received in step S301. For example, the gNB 200 may perform cell reselection priority configuration for slice-based cell reselection in an RRC Release message.

[0108] (4.4) Fourth movement pattern This operation pattern allows UE 100 to prioritize functions of interest (e.g., V2X sidelink communication or MBS) in slice-based cell reselection. The SST in the NSAG / S-NSSAI notified from the NAS to the AS in UE 100 includes standard-defined and operator-defined service type information. If the service indicated by the SST corresponds to a function that UE 100 (AS) desires to consider as the highest priority, UE 100 (AS) considers the cell reselection priority of the frequency providing the service to be the highest priority, or considers the NSAG priority of the NSAG to be the highest priority. This allows slice-based cell reselection and highest priority processing to be compatible.

[0109] That is, in this operation pattern, the UE 100 (AS) acquires prioritized NSAG information indicating a prioritized NSAG from the NAS. The UE 100 (AS) checks whether information indicating a predetermined function (specifically, a function in which the UE 100 is interested) is included in any of the NSAGs indicated by the prioritized NSAG information from the NAS. Then, in response to the information indicating the predetermined function being included in any of the NSAGs, the UE 100 (AS) considers the NSAG including the information indicating the predetermined function or the frequency providing the predetermined function to be the highest priority in cell reselection.

[0110] FIG. 14 is a diagram illustrating an example of operation of the UE 100 according to the fourth operation pattern.

[0111] In step S401, the UE 100 (AS) acquires preferred NSAG information from the NAS. The UE 100 (AS) also receives slice-specific cell reselection information from the gNB 200.

[0112] In step S402, the UE 100 (AS) checks the S-NSSAI in each NSAG included in the priority NSAG information acquired in step S401, and determines the service content from the SST in the S-NSSAI.

[0113] In step S403, the UE 100 (AS) identifies a particular function of interest to it (e.g., MBS or V2X sidelink communication).

[0114] In step S404, the UE 100 (AS) checks whether the specific function identified in step S403 matches any of the service contents identified in step S402.

[0115] If the result of step S404 is YES, in step S405, the UE 100 (AS) may regard the NSAG priority of the NSAG having the matching service content as the highest priority. In this case, the UE 100 (AS) may apply the cell reselection priority of the slice-based cell reselection corresponding to the NSAG to each frequency, and perform cell reselection.

[0116] Alternatively, in step S405, for the NSAG with the highest NSAG priority, if the SST (service content) of the S-NSSAI in the NSAG matches the specific function identified in step S403, UE100 (AS) may perform cell reselection by considering the frequency that provides the specific function as the highest priority based on the slice-specific cell reselection information.

[0117] On the other hand, if the result of step S404 is NO, then in step S406, the UE 100 (AS) may perform normal slice-based cell reselection as defined in the current technical specifications.

[0118] (4.5) Fifth movement pattern In this operation pattern, the UE 100 (AS) identifies the frequency for which cell reselection priority is set in the slice-specific cell reselection information received from the gNB 200 for the highest-priority NSAG indicated by the priority NSAG information acquired from the NAS. Then, the UE 100 (AS) considers the frequency that provides a predetermined function of interest to itself as the highest priority for cell reselection. This allows for both slice-based cell reselection and highest-priority processing.

[0119] FIG. 15 is a diagram illustrating an example of operation of UE 100 according to the fifth operation pattern.

[0120] In step S501, the UE 100 (AS) acquires the priority NSAG information from the NAS.

[0121] In step S502, the UE 100 (AS) identifies a particular function of interest to it (e.g., MBS or V2X sidelink communication).

[0122] In step S503, UE100 (AS) receives slice-specific cell reselection information from gNB200, for example, in SIB16.

[0123] In step S504, the UE 100 (AS) checks the frequency to which the cell reselection priority is set based on the slice-specific cell reselection information for the highest priority NSAG indicated by the priority NSAG information acquired from the NAS.

[0124] In step S505, the UE 100 (AS) checks whether the frequency checked in step S504 matches the frequency that provides the specific function identified in step S502. If the result in step S505 is YES, in step S506, the UE 100 (AS) considers the cell reselection priority of the frequency to be the highest priority.

[0125] On the other hand, if the result of step S505 is NO, in step S507, the UE 100 (AS) may perform normal slice-based cell reselection as defined in the current technical specifications. Here, the UE 100 (AS) determines not to apply the highest priority process and applies the cell reselection priority in slice-based cell reselection to each frequency.

[0126] (5) Other embodiments In the embodiment, an example of processing with the highest priority is shown, but it may also be applied to processing with the lowest priority. Each of the above-mentioned operational flows is not limited to being performed independently, but can be performed 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 perform all steps, and only some steps may be performed.

[0127] In the above-described embodiment and example, an example in which the base station is an NR base station (gNB) has been described, but the base station may be an LTE base station (eNB) or a 6G base station. 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 of the IAB node. The UE 100 may also be an MT (Mobile Termination) of the IAB node.

[0128] Also, the term "network node" primarily refers to a base station, but may also refer to a device in the core network or part of a base station (CU, DU, or RU).

[0129] A program may be provided that causes a computer to execute each process performed by UE100 or gNB200. The program may be recorded on a computer-readable medium. The computer-readable medium can be used to install the program 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 a DVD-ROM. Furthermore, circuits that execute each process performed by UE100 or gNB200 may be integrated, and at least a part of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0130] As used in this disclosure, the terms "based on" and "depending on / in response to" 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 "depending only on" and "depending at least in part on." The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Additionally, the term "or," as used in this disclosure, is not intended to mean an exclusive or. Furthermore, any reference to elements using designations 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, a 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, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0131] 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.

[0132] This application claims priority to U.S. Provisional Application No. 63 / 411,245 (filed September 29, 2022), the entire contents of which are incorporated herein by reference.

[0133] (6) Supplementary notes The following additional notes are about the features of the above-described embodiment.

[0134] (Appendix 1) A cell reselection method for use in a user equipment, comprising: performing slice-based cell reselection in response to the user equipment receiving slice-specific cell reselection information from a network node indicating cell reselection priorities per slice group and per frequency; and determining whether or not to apply a highest priority process in which a frequency or a cell providing a predetermined function different from that of the slice-based cell reselection is considered to have the highest priority for cell reselection, based on whether or not the slice-based cell reselection is being performed to which the slice-specific cell reselection information is applied. Cell reselection method.

[0135] (Appendix 2) The method further includes a step of acquiring prioritized slice group information indicating a prioritized slice group from a NAS (Non-Access Stratum), The determining step includes determining that the highest priority process is applicable when the preferred slice group information is obtained from the NAS but the slice-specific cell reselection information is not received from the network node. 2. A cell reselection method as claimed in claim 1.

[0136] (Appendix 3) The method further includes determining that the highest priority process is applicable in response to a predetermined cell whose wireless quality satisfies a predetermined criterion not supporting the prioritized slice group. 3. The cell reselection method according to claim 1 or 2.

[0137] (Appendix 4) A cell reselection method for use in a user equipment, comprising: In response to the user equipment receiving slice-specific cell reselection information indicating cell reselection priority for each slice group and each frequency from a network node, performing slice-based cell reselection applying the slice-specific cell reselection information; and acquiring, from the network node or a non-access stratum (NAS), setting information for setting whether or not to apply a highest priority process in which a frequency or a cell that provides a predetermined function different from the slice-based cell reselection is considered to have the highest priority for cell reselection. Cell reselection method.

[0138] (Appendix 5) the predetermined function includes a plurality of functions, The setting information is information for setting whether or not the highest priority process is applicable for each of the functions. 5. A cell reselection method as described in Supplementary Note 4.

[0139] (Appendix 6) The setting information is information for setting which of the slice-based cell reselection and the highest priority process is to be prioritized in cell reselection. 5. A cell reselection method as described in Supplementary Note 4.

[0140] (Appendix 7) the predetermined function includes a plurality of functions, The setting information is information that sets priorities in cell reselection for the slice-based cell reselection and for each of a plurality of functions included in the predetermined function. 5. A cell reselection method as described in Supplementary Note 4.

[0141] (Appendix 8) A cell reselection method for use in a user equipment, comprising: transmitting preference information to a network indicating a preference of the user equipment regarding whether slice-based cell reselection or a predetermined function different from the slice-based cell reselection is to be prioritized in cell reselection; and controlling the slice-based cell reselection and a highest priority process in which a frequency or a cell that provides the predetermined functionality is considered the highest priority for cell reselection in response to configuration information received from the network based on the preference information. Cell reselection method.

[0142] (Appendix 9) the predetermined function includes a plurality of functions, The preference information is information indicating a priority preference in cell reselection for the slice-based cell reselection and each of the plurality of functions. 9. The cell reselection method according to claim 8.

[0143] (Appendix 10) A cell reselection method for use in a user equipment, comprising: acquiring priority slice group information indicating a priority slice group from a NAS (Non-Access Stratum); determining whether information indicating a predetermined function different from the slice-based cell reselection is included in any of the slice groups indicated by the preferred slice group information; In response to the information indicating the predetermined function being included in any of the slice groups, the slice group including the information indicating the predetermined function or the frequency providing the predetermined function is considered to have the highest priority in cell reselection. Cell reselection method.

[0144] (Appendix 11) A cell reselection method for use in a user equipment, comprising: acquiring priority slice group information indicating a priority slice group from a NAS (Non-Access Stratum); performing a predetermined function different from the slice-based cell reselection; receiving slice-specific cell reselection information from a network node indicating cell reselection priorities per slice group and per frequency; and a step of regarding a frequency that provides the predetermined function as the highest priority in cell reselection among frequencies for which the cell reselection priority is set in the slice-specific cell reselection information for the highest priority slice group indicated by the priority slice group information. Cell reselection method.

[0145] (Appendix 12) The predetermined function includes at least one of MBS (Multicast / Broadcast Services), V2X sidelink, NR sidelink, and HSDN (High Speed ​​Dedicated Network). 12. A cell reselection method according to any one of Supplementary Notes 1 to 11.

[0146] (7) Supplementary Notes Supplementary notes regarding the above-described embodiment will be added. introduction In RAN2#119e, further consideration is required as to whether / how to handle cell reselection priority from the perspective of "MBS or HSDN highest priority rule" and "slice-specific cell reselection priority."

[0147] (1) Between MBS and slice-specific cell reselection Further study is needed to determine whether the frequency prioritization procedure of MBS is affected by slice-based reselection priorities. (2) Between HSDN and slice-specific cell reselection 19: Postpone coexistence of HSDN and slice-specific cell reselection (not sure how this works in this release).

[0148] This appendix discusses the coexistence of cell reselection between the highest priority rule and slice-specific cell reselection priorities.

[0149] Discussion A summary of the highest priority rules in TS38.304 is as follows: [Table 1]

[0150] Observation 1: The current specification gives highest priority to HSDN cells and highest priority to V2X sidelink / NR sidelink / MBS frequencies.

[0151] Observation 2: According to the current specification, highest priority means higher than any other priority (i.e., 0-7) configured in the network.

[0152] HSDN is specified to support specific network policies, such as arranging HSDN cells along high-speed railways so that UEs moving at high speeds can prioritize HSDN cells during cell reselection.

[0153] On the other hand, the V2X sidelink, NR sidelink, and MBS frequency are supported for user selection. For example, if a user is interested in MBS services, the UE will prioritize the MBS frequency of interest.

[0154] Observation 3: The HSDN cell selection is determined by network policy, while the V2X sidelink / NR sidelink / MBS frequency selection is determined by user preference.

[0155] For slice-specific cell reselection, NSAG priority is set by the AMF and NSAG frequency priority is set from the gNB, so it is considered to support network policies.

[0156] Observation 4: Cell reselection priority per slice is determined by network policy.

[0157] It is difficult for the network to grasp the latest user preferences, especially when the UE is idle / inactive, so it is considered necessary to prioritize user preferences over network policies. For example, if a user is interested in receiving MBS services, the UE needs to camp on a cell / frequency that provides MBS services. Guiding such UEs to a cell / frequency, for example by slice-specific cell reselection, is difficult given that user preferences change from time to time. Therefore, RAN2 needs to ensure that user preferences always take precedence over network policies, as is the case currently.

[0158] Observation 5: It may be difficult for the network to know the latest user preferences, especially when the UE is in idle / inactive state.

[0159] Proposal 1: RAN2 should ensure that user priorities take precedence over current network policies, i.e., no changes are needed to the highest priority rules for V2X and MBS.

[0160] On the other hand, when it comes to prioritization within the network policy, i.e., prioritization between HSDN and slice-specific cell reselection, it is entirely up to the network how the UE behaves. In some deployments, it may be better to prioritize HSDN over slice-specific cell reselection, while in other deployments it may be the other way around. So, as a compromise, the network could indicate to the UE which feature should take priority, i.e., slice-specific cell reselection priority or the highest priority of HSDN.

[0161] Observation 6: Prioritization within network policies is up to the network and its operations to prioritize slice-specific cell reselection priorities over HSDN highest priorities, or vice versa.

[0162] Proposal 2: The gNB indicates to the UE whether to prioritize slice-specific cell reselection priorities or the highest priority HSDN cell. [Explanation of symbols]

[0163] 1: Mobile communication system 10:RAN 20 :CN 100: UE (user equipment) 110: Receiving unit 120: Transmitter 130: Control unit 200:gNB (base station) 210: Transmission unit 220: Receiving unit 230: Control unit 240: Backhaul communication unit

Claims

1. A cell reselection method for use in a user equipment, comprising: performing slice-based cell reselection in response to the user equipment receiving slice-specific cell reselection information from a base station indicating cell reselection priorities for each slice group and each frequency; If a predetermined function different from the slice-based cell reselection is set or there is an interest in performing the predetermined function, performing a process of regarding a frequency that provides the predetermined function as the highest priority for cell reselection, rather than the cell reselection priority indicated by the slice-specific cell reselection information; The user equipment performs a process of regarding a frequency that provides a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection, with higher priority than the process of regarding a frequency that provides a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection. Cell reselection method.

2. The predetermined function includes at least one of MBS (Multicast / Broadcast Services), NR sidelink, and V2X sidelink. The cell reselection method according to claim 1 .

3. A user device, A receiver that receives slice-specific cell reselection information indicating cell reselection priority for each slice group and each frequency from a base station, and a control unit that performs slice-based cell reselection in response to reception of the slice-specific cell reselection information, If the user equipment is configured with a predetermined function different from the slice-based cell reselection or is interested in performing the predetermined function, the control unit performs a process of regarding a frequency that provides the predetermined function as the highest priority for cell reselection, rather than the cell reselection priority indicated by the slice-specific cell reselection information, The control unit performs a process of regarding a frequency that provides a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection, with higher priority than the process of regarding a frequency that provides a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection. User equipment.

4. A system including a user equipment and a base station, The user device A receiving unit that receives slice-specific cell reselection information indicating cell reselection priority for each slice group and each frequency from a base station; A control unit that performs slice-based cell reselection in response to receiving the slice-specific cell reselection information, If the user equipment is configured with a predetermined function different from the slice-based cell reselection or is interested in performing the predetermined function, the control unit performs a process of regarding a frequency that provides the predetermined function as the highest priority for cell reselection, rather than the cell reselection priority indicated by the slice-specific cell reselection information, The control unit performs a process of regarding a frequency providing a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection, with higher priority than the process of regarding the frequency providing a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection, The base station a transmitter for transmitting the slice-specific cell reselection information to the user equipment; system.

5. A program for a user device, the program comprising: receiving slice-specific cell reselection information from a base station, the slice-specific cell reselection information indicating cell reselection priorities for each slice group and each frequency; performing slice-based cell reselection in response to receiving the slice-specific cell reselection information; If the user equipment is configured with a predetermined function different from the slice-based cell reselection or is interested in performing the predetermined function, a process of considering a frequency that provides the predetermined function as the highest priority for cell reselection, rather than the cell reselection priority indicated by the slice-specific cell reselection information; and performing a process of regarding a frequency that provides a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection, with higher priority than the process of regarding the frequency that provides a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection. program.

6. A chipset for a user device, comprising: receiving slice-specific cell reselection information from a base station, the slice-specific cell reselection information indicating cell reselection priorities for each slice group and each frequency; performing slice-based cell reselection in response to receiving the slice-specific cell reselection information; If the user equipment is configured with a predetermined function different from the slice-based cell reselection or is interested in performing the predetermined function, a process of considering a frequency that provides the predetermined function as the highest priority for cell reselection, rather than the cell reselection priority indicated by the slice-specific cell reselection information; and performing a process of regarding a frequency that provides a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection, with higher priority than the process of regarding the frequency that provides a High Speed ​​Dedicated Network (HSDN) as the highest priority for the cell reselection. Chipset.

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