Communication control method, mobile communication system, user device, program, and chipset

Abstract

A communication control method according to a first embodiment is for a mobile communication system that comprises a user device and a base station and that enables wireless communication between the user device and the base station. The communication control method comprises a step of a first layer of the user device in a radio resource control (RRC) idle state or an RRC inactive state receiving system information from the base station. The communication control method comprises the first layer of the user device notifying, on the basis of the system information, at least one of first information indicating whether slice-specific cell reselection is possible and second information indicating whether slice-specific random-access channel is possible, to a second layer higher than the first layer.

Description

[Technical Field]

[0001] The present disclosure relates to a communication control method used in a mobile communication system. [Background technology]

[0002] Network slicing (or network slice) has been specified in the 3GPP (Third Generation Partnership Project), a standardization project for mobile communication systems.

[0003] Network slicing is a concept that allows differentiated processing according to the requirements of each customer. Alternatively, network slicing is a technology that virtually slices a network to efficiently provide a network that meets the requirements of the services used by customers. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TS 38.300 V16.6.0 (2021-06) Summary of the Invention

[0005] A communication control method according to a first aspect is a communication control method in a mobile communication system including a user device and a base station, and capable of wireless communication between the user device and the base station. The communication control method includes a step in which a first layer of the user device in an RRC (Radio Resource Control) idle state or an RRC inactive state receives system information from the base station. The communication control method includes a step in which the first layer of the user device notifies a second layer higher than the first layer of at least one of first information indicating whether slice-specific cell reselection is possible or not and second information indicating whether slice-specific random access channel is possible or not, based on the system information.

[0006] A communication control method according to a second aspect is a communication control method in a mobile communication system including a user equipment and a base station, and capable of wireless communication between the user equipment and the base station. The communication control method includes a step in which a first layer of the user equipment in an RRC connected state with the base station notifies a second layer higher than the first layer of at least one of third information indicating whether or not parameters related to slice-specific cell reselection have been acquired and fourth information indicating whether or not parameters related to a slice-specific random access channel have been acquired. The communication control method also includes a step in which the second layer of the user equipment notifies the first layer of fifth information indicating whether the user equipment should remain in an RRC connected state or transition to an RRC idle state or an RRC inactive state, based on at least one of the third information and the fourth information. The communication control method further includes a step in which the first layer transmits the fifth information to the base station.

[0007] A communication control method according to a third aspect is a communication control method in a mobile communication system including a user device and a base station, and capable of wireless communication between the user device and the base station. The communication control method includes a step in which a first layer of a user device in an RRC idle state or an RRC inactive state performs slice-specific cell reselection. The communication control method also includes a step in which, when the first layer completes the slice-specific cell reselection, the first layer notifies a second layer higher than the first layer of a completion notification. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a mobile communication system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a configuration example of a UE (user equipment) according to an embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example configuration of a gNB (base station) according to one embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of a protocol stack related to a user plane according to an embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of a protocol stack related to a control plane according to an embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of the relationship between layers according to the first embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of operation according to the first embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of the configuration of a mobile communication system 1 according to the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of operation according to the second embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of operation according to the third embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of operation according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An object of the present disclosure is to provide a communication control method that allows appropriate exchange of information about slices between an access stratum (AS) and a non-access stratum (NAS).

[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] (Mobile communication system) First, a configuration of a mobile communication system according to an embodiment will be described. The mobile communication system according to an embodiment is a 3GPP 5G system, but LTE may be applied at least partially to the mobile communication system. Furthermore, future mobile communication systems such as 6G may also be applied to the mobile communication system.

[0012] FIG. 1 is a diagram illustrating an example of the configuration of a mobile communication system 1 according to an embodiment.

[0013] As shown in FIG. 1, 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.

[0014] The UE 100 is a mobile device. The UE 100 may be any device that is used by a user. For example, the UE 100 may be a mobile phone terminal (including a smartphone), 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).

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

[0016] The gNB 200 may be connected to an EPC (Evolved Packet Core), which is a core network of LTE. (or LTE base stations )、 The gNB 200 may be connected to the 5GC 20. Also, the LTE base station and the gNB 200 may be connected via an inter-base station interface.

[0017] The 5GC 20 includes an AMF (Access and Mobility Management Function) 301 (301-1, 301-2) and a UPF (User Plane Function) 302 (302-1, 302-2). The AMF 301 performs various mobility controls for the UE 100. The AMF 301 manages information about the area in which the UE 100 is located by communicating with the UE 100 using NAS (Non-Access Stratum) signaling. The UPF 302 controls data forwarding. The AMF 301 and the UPF 302 are connected to the gNB 200 via an NG interface, which is an interface between a base station and a core network. The AMF 301 and the UPF 302 are examples of core network devices connected to the 5GC (core network) 20.

[0018] FIG. 2 is a diagram illustrating an example of the configuration of a UE 100 (user equipment) according to an embodiment.

[0019] As shown in FIG. 2, the UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit .

[0020] 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 (down-converts) a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

[0021] 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 (up-converts) a baseband signal (transmission signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0022] The control unit 130 performs various controls in the UE 100. , smallThe UE 100 includes at least one processor and at least one memory electrically connected to the processor. 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, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in the memory to perform various processes. The control unit 130 may perform various operations and various processes executed by the UE 100 in each of the embodiments described below.

[0023] FIG. 3 is a diagram illustrating an example configuration of a gNB200 (base station) according to one embodiment.

[0024] As shown in FIG. 3, the gNB 200 has a transmitter 210, a receiver 220, a controller 230, and a backhaul communication unit 240.

[0025] 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 (up-converts) a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna.

[0026] 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 (down-converts) a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

[0027] The control unit 230 performs various controls in the gNB 200. The control unit 230 includes at least one processor and at least one memory electrically connected to the processor. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation, encoding / decoding, etc. of baseband signals. The CPU executes programs stored in the memory to perform various processes. The control unit 230 may perform various operations and various processes executed by the gNB 200 in each of the embodiments described below.

[0028] The backhaul communication unit 240 is connected to neighboring base stations via an inter-base station interface. The backhaul communication unit 240 is connected to the AMF 301 and / or the UPF 302 via a base station-core network interface. Note that the gNB is composed of a CU (Central Unit) and a DU (Distributed Unit), and both units may be connected via an F1 interface.

[0029] FIG. 4 is a diagram illustrating an example of the configuration of a protocol stack of a radio interface of a user plane according to an embodiment.

[0030] As shown in Figure 4, the radio interface protocol of the user plane that handles data has 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.

[0031] 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 the UE 100 and the PHY layer of the gNB 200 via a physical channel.

[0032] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of UE 100 and the MAC layer of gNB 200 via transport channels. The MAC layer of gNB 200 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 UE 100.

[0033] 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.

[0034] The PDCP layer performs header compression / decompression, encryption / decryption. Data and control information are transmitted between the PDCP layer of the UE 100 and the PDCP layer of the gNB 200 via a radio bearer.

[0035] The SDAP layer maps QoS 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 may not be required.

[0036] FIG. 5 is a diagram illustrating an example of the configuration of a protocol stack of a radio interface of a control plane according to an embodiment.

[0037] As shown in FIG. 5, the protocol stack of the radio interface of the control plane that handles signaling (control signals) has an RRC (Radio Resource Control) layer and an NAS layer instead of the SDAP layer shown in FIG.

[0038] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of gNB200. The RRC layer controls logical channels, transport channels, and physical channels 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 RRC connection is suspended, UE100 is in an RRC inactive state.

[0039] A Non-Access Stratum (NAS) layer positioned 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 301.

[0040] The UE 100 has an application layer and the like in addition to the radio interface protocol.

[0041] [First embodiment] Next, a first embodiment will be described.

[0042] 6 is a diagram illustrating an example of the relationship between layers according to the first embodiment. As illustrated in FIG. 6, the UE 100 includes an AS layer 140, an NAS layer 150, and an upper layer 160.

[0043] The AS layer 140 includes each layer of the control plane of the radio interface shown in Fig. 5. That is, the AS layer 140 includes a PHY layer, a MAC layer, an RLC layer, a PDCP layer, and an RRC layer.

[0044] 6, an upper layer 160 exists as a layer above the NAS layer 150. The upper layer 160 includes, for example, an application layer.

[0045] Slice information related to the network slicing of the serving cell is handled by the NAS layer 150. On the other hand, information related to the cell is handled by the AS layer 140. When the AS layer 140 of the UE 100 receives slice information, the AS layer 140 notifies the NAS layer 150 of the received slice information. This allows the NAS layer 150 to grasp the slice information. Such processing may be performed, for example, within the control unit 130.

[0046] In the following, network slicing may be referred to as a "slice." In network slicing, the part supported by NG-RAN 10 may be referred to as RAN slicing. Even when there is no distinction between network slicing and RAN slicing, they may be simply referred to as "slice" in the following.

[0047] A slice refers to a logically divided core network and / or radio access network. An identifier for identifying a slice is an NSSAI or an S-NSSAI, for example.

[0048] A slice group is a group including one or more slices, and an identifier (ID) is assigned to the group. The slice group may be created in a core network (e.g., AMF 301) or a radio access network (e.g., gNB 200). The created slice group may be notified to the UE 100.

[0049] Slice-specific cell reselection is being studied in 3GPP. In slice-specific cell reselection, frequencies are mapped (or linked) to each slice, and a priority (absolute priority) is set for each frequency. Cell reselection using this setting is called slice-specific cell reselection. Slice-specific cell reselection makes it possible to provide frequency resources for each slice (or slice group), thereby preventing overlap of the frequency resources between slices. Furthermore, by controlling the frequency priority of the cell on which UE 100 camps (the cell to be reselected) for each slice (or slice group), UE 100 can be camped (distributed / distributed) on an appropriate frequency for each slice that UE 100 wishes to access. Furthermore, UE 100 can be camped (distributed) on a different frequency (or cell) from UEs (e.g., legacy UEs) that do not wish to access the slice.

[0050] Regarding slice-specific cell reselection, 3GPP has 1) Prioritized frequencies mapped to each slice are provided to the UE 100; 2) "slice" may mean "slice group"; 3) The prioritized frequencies mapped to each slice are displayed in “Slice info.” It was agreed that it would be part of

[0051] Also, in 3GPP, slice-specific random access channels (Slice-specific RACH (Random Access Channel(s))) are being studied. A random access procedure performed using a separated random access opportunity (separated RO (RACH Occasion)) and / or a separated preamble for each slice or slice group is called a slice-specific random access channel (hereinafter, may be referred to as a "slice-specific RACH"). The slice-specific RACH makes it possible to provide a RACH resource for each slice or slice group, for example, and can prevent the resource from overlapping between slices, between slice groups, or between access using a slice and access not using a slice. Furthermore, by avoiding the resource overlap, it is possible to suppress interference between RACHs transmitted by multiple UEs 100. Furthermore, it is possible to prioritize access to a certain slice or slice group (by allocating resources that are less likely to cause interference).

[0052] Furthermore, 3GPP is also considering an "intended slice." However, 3GPP has not yet reached a specific agreement on the definition of the "intended slice." In the first embodiment, a slice that is likely to be used, a candidate slice, a desired slice, a slice desired for communication, a requested slice, an allowed slice, or an intended slice is referred to as an "intended slice." For example, when the NAS layer 150 notifies the AS layer 140 of the "intended slice," the AS layer 140 can perform various processes, such as a cell reselection process, using the "intended slice."

[0053] However, the above-described slice-specific cell reselection and slice-specific RACH have the following problems: That is, both slice-specific cell reselection and slice-specific RACH are processes performed in the AS layer 140. However, the NAS layer 150 has no method for determining whether the serving cell supports slice-specific cell reselection (or slice-specific RACH).

[0054] Furthermore, the above-mentioned "intended slice" also has the following problem: Depending on the timing of notification from the NAS layer 150 to the AS layer 140, the AS layer 140 may not be able to perform processing related to the "intended slice" at the appropriate time.

[0055] Therefore, in the first embodiment, when the AS layer 140 of the UE 100 in the RRC idle state or the RRC inactive state acquires parameters related to slice-specific cell reselection or slice-specific RACH, it notifies the NAS layer 150 that slice-specific cell reselection or slice-specific RACH is possible in the serving cell.

[0056] Specifically, first, a first layer (e.g., AS layer 140) of a user equipment (e.g., UE 100) in an RRC idle state or an RRC inactive state receives system information from a base station (e.g., gNB 200). Second, the first layer of the user equipment notifies a second layer (e.g., NAS layer 150) higher than the first layer of at least one of first information indicating whether slice-specific cell reselection is possible or not and second information indicating whether slice-specific RACH is possible or not based on the system information.

[0057] This allows the NAS layer 150 to determine whether slice-specific cell reselection is possible in the serving cell. Also, the NAS layer 150 can determine whether slice-specific RACH is possible in the serving cell. Then, the NAS layer 150 can perform appropriate processing based on this information.

[0058] In the following, there may be a description of a "slice identifier." In this case, the "slice identifier" may include an S-NSSAI, an NSSAI, or a slice group ID.

[0059] (Operation example according to the first embodiment) FIG. 7 is a diagram illustrating an example of operation according to the first embodiment.

[0060] As shown in FIG. 7, in step S10, the UE 100 is in an RRC idle state (hereinafter, may be referred to as an "idle state") or an RRC inactive state (hereinafter, may be referred to as an "inactive state").

[0061] In step S11, the AS layer 140 of the UE 100 performs cell selection or cell reselection. Here, the cell reselection may be slice-specific cell reselection. Alternatively, the cell reselection may be normal (conventional) cell reselection that is not slice-specific cell reselection.

[0062] In the case of slice-specific cell reselection, the AS layer 140 may select a cell using prioritized frequencies associated with each slice.

[0063] Also, normal cell selection or cell reselection may select a suitable cell based on cell selection criteria, and if camped on a cell, may select a better cell according to cell reselection criteria.

[0064] Fig. 8 is a diagram illustrating a configuration example of a mobile communication system 1 according to the first embodiment. Fig. 8 illustrates an example in which a UE 100 in an idle state or an inactive state selects cell #1 by cell selection or cell reselection.

[0065] 7, in step S12, the AS layer 140 receives a system information block (SIB) broadcast from the selected cell. Note that step S12 may be performed when the AS layer 140 receives an updated SIB, rather than when the AS layer 140 selects a cell.

[0066] In step S13, the AS layer 140 checks whether the received SIB includes parameters related to slice-specific cell reselection (hereinafter, may be referred to as "slice-specific cell reselection parameters"). Also, in step S13, the AS layer 140 checks whether the received SIB includes parameters related to slice-specific RACH (hereinafter, may be referred to as "slice-specific RACH parameters").

[0067] In step S14, the AS layer 140 sends a first notification to the NAS layer 150 according to the confirmation result.

[0068] First, when the AS layer 140 confirms that the slice-specific cell reselection parameters are included in the SIB, it notifies the NAS layer 150 of a first notification including information indicating that slice-specific cell reselection is possible in the serving cell. The first notification may include a slice identifier for which the slice-specific cell reselection parameters are provided. In other words, when a slice identifier and a slice-specific cell reselection parameter associated with the slice identifier are provided in the SIB, the AS layer 140 may notify the NAS layer 150 of the first notification including the slice identifier. The slice identifier included in the first notification may be one or more (for example, in a list format).

[0069] When the AS layer 140 receives the "intended slice" from the NAS layer 150 and confirms that slice-specific cell reselection parameters related to the "intended slice" are included in the SIB, the AS layer 140 transmits a first notification including information indicating that slice-specific cell reselection for the "intended slice" is possible. The AS layer 140 can confirm whether slice-specific cell reselection parameters related to the "intended slice" are included in the SIB, for example, based on the slice identifier of the "intended slice" and the slice identifier linked to the slice-specific cell reselection parameters included in the SIB.

[0070] Second, when the AS layer 140 confirms that the slice-specific RACH parameters are included in the SIB, the AS layer 140 transmits a first notification including information indicating that the slice-specific RACH is available in the serving cell. The first notification may include a slice identifier for which the slice-specific RACH parameters are provided. In other words, when the SIB provides a slice identifier and slice-specific RACH parameters associated with the slice identifier, the AS layer 140 may transmit the first notification including the slice identifier to the NAS layer 150. The slice identifier included in the first notification may be one or more (for example, in a list format).

[0071] In this case as well, when the AS layer 140 receives the "intended slice" from the NAS layer 150 and confirms that slice-specific RACH parameters related to the "intended slice" are included in the SIB, the AS layer 140 transmits a first notification including information indicating that a slice-specific RACH for the "intended slice" is possible. The AS layer 140 can confirm whether slice-specific RACH parameters related to the "intended slice" are included in the SIB, for example, based on the slice identifier of the "intended slice" and the slice identifier linked to the slice-specific RACH parameters included in the SIB.

[0072] Third, when the AS layer 140 confirms that the slice-specific cell reselection parameters are not included in the SIB, it notifies the NAS layer 150 of a first notification including information indicating that slice-specific cell reselection is not possible in the serving cell. The first notification may include a slice identifier for which the slice-specific cell reselection parameters are not provided. In other words, if the SIB does not provide a slice identifier and a slice-specific cell reselection parameter associated with the slice identifier, the AS layer 140 may notify the NAS layer 150 of a first notification including the slice identifier. The slice identifier included in the first notification may be one or more (for example, in a list format).

[0073] In addition, when the AS layer 140 receives an "intended slice" from the NAS layer 150, if it confirms that the SIB does not include slice-specific cell reselection parameters for the "intended slice," it notifies the NAS layer 150 of a first notification including information indicating that slice-specific cell reselection for the "intended slice" is not possible.

[0074] Fourth, when the AS layer 140 confirms that the slice-specific RACH parameters are not included in the SIB, the AS layer 140 transmits a first notification including information indicating that the slice-specific RACH is not possible in the serving cell. The first notification may include a slice identifier for which the slice-specific RACH parameters are not provided. In other words, if the SIB does not provide a slice identifier and slice-specific RACH parameters associated with the slice identifier, the AS layer 140 may transmit a first notification including the slice identifier to the NAS layer 150. The slice identifier included in the first notification may be one or more (for example, in a list format).

[0075] In this case too, when the AS layer 140 receives an "intended slice" from the NAS layer 150, and confirms that the SIB does not include slice-specific RACH parameters for the "intended slice," it notifies the first notification including information indicating that slice-specific RACH for the "intended slice" is not possible.

[0076] The first notification in step S14 may be notified when the state of slice-specific cell reselection changes from "possible" to "impossible" (or vice versa). Alternatively, the first notification in step S14 may be notified when the state of slice-specific RACH changes from "possible" to "impossible" (or vice versa).

[0077] Furthermore, the AS layer 140 may appropriately combine the above-described four cases. For example, when the AS layer 140 confirms that two parameters, a slice-specific cell reselection parameter and a slice-specific RACH parameter, are included in the SIB, the AS layer 140 may transmit a first notification including information indicating that slice-specific cell reselection and slice-specific RACH are possible.

[0078] Furthermore, if a slice identifier is associated with each parameter, the AS layer 140 may notify the NAS layer 150 of the first notification for each slice identifier. For example, it is assumed that S-NSSAI#1 to #4 exist. It is also assumed that the UE 100 moves from a first cell to a second cell by cell selection or cell reselection (step S11). It is further assumed that, due to the movement, the parameters associated with each of the S-NSSAI#1 to #4 (which may be referred to as "parameters" when slice-specific cell reselection parameters and slice-specific RACH parameters are not distinguished from each other) may or may not exist depending on the cell. For example, for S-NSSAI#1, there may be a parameter associated with the slice identifier in one cell, but not in another cell. This is because, even with the same slice identifier, slice-specific cell reselection (or slice-specific RACH) may or may not be supported depending on the cell.

[0079] The AS layer 140 notifies the NAS layer 150 of the first notification, specifically, the following.

[0080] (S-NSSAI#1) It is assumed that, for S-NSSAI#1, the first cell before the move does not have parameters associated with S-NSSAI#1, and the second cell after the move has parameters associated with S-NSSAI#1. In this case, when AS layer 140 confirms that slice-specific cell reselection parameters are included in the SIB in the second cell, it notifies NAS layer 150 of information indicating that slice-specific cell reselection is supported in the second cell. Furthermore, when AS layer 140 confirms that slice-specific RACH parameters are included in the SIB, it notifies NAS layer 150 of information indicating that slice-specific RACH is supported in the second cell. When AS layer 140 confirms both of the two parameters, it notifies of information indicating that both are supported.

[0081] (S-NSSAI#2) For S-NSSAI#2, it is assumed that the first cell before the move has parameters associated with S-NSSAI#2, and the second cell after the move has no parameters associated with S-NSSAI#2. In this case, when AS layer 140 confirms that slice-specific cell reselection parameters are not included in the SIB in the second cell, it notifies NAS layer 150 of information indicating that slice-specific cell reselection is not supported in the second cell. Furthermore, when AS layer 140 confirms that slice-specific RACH parameters are not included in the SIB, it notifies NAS layer 150 of information indicating that slice-specific RACH is not supported in the second cell.

[0082] (S-NSSAI#3) For S-NSSAI#3, it is assumed that the first cell has no parameters associated with S-NSSAI#3, and the second cell also has no parameters associated with S-NSSAI#3. In this case, when AS layer 140 confirms that slice-specific cell reselection parameters are not included in the SIB in the second cell, it notifies NAS layer 150 of information indicating that slice-specific cell reselection is not supported in the second cell. Furthermore, when AS layer 140 confirms that slice-specific RACH parameters are not included in the SIB, it notifies NAS layer 150 of information indicating that slice-specific RACH is not supported in the second cell. In this case, since there is no change in the presence or absence of parameters before and after cell movement, AS layer 140 does not need to notify the first notification.

[0083] (S-NSSAI#4) For S-NSSAI#4, it is assumed that the first cell has parameters associated with S-NSSAI#4 and the second cell also has parameters associated with S-NSSAI#4. In this case, when AS layer 140 confirms that slice-specific cell reselection parameters are included in the SIB in the second cell, it notifies NAS layer 150 of information indicating that slice-specific cell reselection is supported in the second cell. Furthermore, when AS layer 140 confirms that slice-specific RACH parameters are included in the SIB in the second cell, it notifies NAS layer 150 of information indicating that slice-specific RACH is supported in the second cell. In this case, too, since there is no change in the presence or absence of parameters before and after cell movement, AS layer 140 does not need to notify the first notification.

[0084] The above-mentioned first notification may be the following notification that is not related to slice-specific cell reselection and slice-specific RACH:

[0085] (A1) A first notification including information indicating that the serving cell supports or does not support network slicing.

[0086] (A2) A first notification including information indicating that the serving cell supports or does not support RAN slicing.

[0087] (A3) A first notification including information indicating that the serving cell supports or does not support a slice of a particular slice identifier.

[0088] (A4) A first notification including information indicating whether the serving cell supports or does not support prioritized access to a slice with a specific slice identifier. For example, if the AS layer 140 acquires slice-specific RACH parameters associated with a specific slice identifier, the AS layer 140 can access the cell having the slice through a RACH procedure. Therefore, the AS layer 140 can confirm whether prioritized access to the slice is supported by determining whether the AS layer 140 acquires the slice-specific RACH parameters from the SIB.

[0089] The above is the operation of step S14.

[0090] In step S15, the NAS layer 150 performs a predetermined operation. A specific example of the predetermined operation will be explained in the second embodiment.

[0091] Thereafter, the UE 100 may perform cell selection or cell reselection (step S11) and repeat the above-described processing.

[0092] (Modification of the first embodiment) In the first embodiment, slice-specific cell reselection has been described. For example, as a modified example of the first embodiment, slice-specific cell selection may be performed instead of slice-specific cell reselection. In the slice-specific cell selection, for example, a frequency is associated with each slice, and a priority is assigned to the frequency. When performing slice-specific cell selection, the UE 100 may perform cell selection using the setting.

[0093] In the first embodiment, an example has been described in which the UE 100 acquires each parameter from an SIB. For example, as a modification of the first embodiment, the UE 100 may acquire each parameter by dedicated signaling such as an RRC Release message or an RRC Reconfiguration message instead of the SIB.

[0094] Furthermore, in the first embodiment, an example has been described in which UE100 acquires each parameter of a selected cell from the selected cell. For example, as a modified example of the first embodiment, UE100 may receive an SIB broadcast from a neighboring cell adjacent to the selected cell (or the serving cell), and acquire each parameter of the neighboring cell from the received SIB. Then, AS layer 140 of UE100 may notify NAS layer 150 of a first notification including information indicating whether slice-specific cell reselection and / or slice-specific RACH are supported in the neighboring cell, depending on whether each parameter has been acquired. Alternatively, UE100 may receive neighboring cell information broadcast from the serving cell, and acquire information indicating whether slice-specific cell reselection and / or slice-specific RACH are supported in the neighboring cell based on the neighboring cell information.

[0095] Furthermore, in the first embodiment, an example has been described in which the UE 100 is in an idle state or an inactive state. For example, the UE 100 may be in a connected state. The UE 100 in the connected state can receive the SIB broadcast from the base station 200 and perform the processing described in the first embodiment.

[0096] [Second embodiment] Next, a second embodiment will be described.

[0097] In the second embodiment, a specific example of the "predetermined operation" in the first embodiment will be described.

[0098] Specifically, the second layer (e.g., NAS layer 150) of the user equipment (e.g., UE 100) performs a predetermined operation based on at least one of the first information (e.g., information indicating whether slice-specific cell reselection is supported in the serving cell) and the second information (e.g., information indicating whether slice-specific RACH is supported in the serving cell).

[0099] (Operation example according to the second embodiment) FIG. 9 is a diagram illustrating an example of operation according to the second embodiment.

[0100] In FIG. 9, steps S20 and S21 are the same as steps S10 and S14, respectively, in the first embodiment.

[0101] In step S22, the NAS layer 150 may send the second notification to the AS layer 140. In step S23, the NAS layer 150 may send the third notification to the upper layer 160. The order of steps S22 and S23 may be reversed.

[0102] In this way, the predetermined operation includes a second notification from the NAS layer 150 to the AS layer 140, and a third notification from the NAS layer 150 to the upper layer 160. The two cases will be explained below.

[0103] (Second notice) The NAS layer 150 may (again) notify the "intended slice" as the second notification. For example, consider a case where the NAS layer 150 receives, as the first notification, information indicating that priority access to a specific slice is supported (e.g., (A4) in the first embodiment), and the specific slice is an "intended slice." In such a case, the NAS layer 150 may again notify the "intended slice" as the second notification to notify that the specific slice that is available for priority access is an "intended slice."

[0104] Furthermore, the NAS layer 150 may notify slice priority as the second notification. For example, consider a case where the NAS layer 150 receives, as the first notification, information indicating that slice-specific cell reselection is possible for multiple slices. In such a case, the NAS layer 150 may notify the second notification including information indicating a slice identifier and a priority for each of the multiple slices.

[0105] Furthermore, the NAS layer 150 may transmit a second notification including a request (initiation) for RRC connection establishment with prioritized access. For example, consider a case where the NAS layer 150 receives information indicating that a slice-specific RACH is available. In such a case, the AS layer 140 can connect to the cell using slice-specific RACH parameters. Therefore, the NAS layer 150 may request the AS layer 140 to establish an RRC connection with prioritized access using the slice-specific RACH.

[0106] Furthermore, the NAS layer 150 may notify a second notification including an instruction for a PLMN (Public Land Mobile Network) search or a cell search. For example, the NAS layer 150 may notify such a second notification when, even if it receives information indicating that slice-specific cell reselection is possible for the serving cell, it requests access to another cell instead of the serving cell.

[0107] Furthermore, the NAS layer 150 may transmit a second notification including information indicating a frequency priority associated with the slice. For example, when using a URLLC slice, the NAS layer 150 may notify the AS layer 140 of the priority of a frequency associated with the slice to prioritize the use of a particular frequency F1.

[0108] Furthermore, if multiple slice groups exist, the NAS layer 150 may notify a second notification including the priority order among the slice groups.

[0109] Furthermore, the NAS layer 150 may transmit a second notification including a change request for a PLMN (Public Land Mobile Network) or a Standalone Non-Public Network (SNPN). For example, if the NAS layer 150 knows that an "intended slice" exists in a PLMN other than the serving PLMN, May be notifiedUpon receiving the second notification, the AS layer 140 may search for PLMNs other than the serving PLMN and notify the NAS layer 150 of the search results. The same applies to the case of an SNPN.

[0110] (Third notice) The NAS layer 150 may notify an application using a slice of information indicating whether priority access to the slice is possible or impossible as a third notification. Upon receiving the notification, the application may perform, for example, the following process.

[0111] First, the application may display on the display of the UE 100 whether priority access is available or unavailable.

[0112] Second, the application may perform processing depending on whether priority access is available or unavailable. If priority access is unavailable, the application may establish a connection with the gNB 200 (or cell) by transmitting a dummy packet to the gNB 200 before transmitting a data packet. This allows the application to transmit the data packet without delay because the connection is already established at the time of actually transmitting the data packet.

[0113] (Modification of the second embodiment) In the second embodiment, an example has been described in which the UE 100 is in an idle state or an inactive state. For example, the UE 100 may be in a connected state. The UE 100 in the connected state can receive the SIB broadcast from the base station 200 and perform the processing described in the second embodiment.

[0114] [Third embodiment] Next, a third embodiment will be described.

[0115] In the third embodiment, the NAS layer 150 of the UE 100 transmits the RRC state request to the gNB 200 via the AS layer 140.

[0116] Specifically, first, a first layer (e.g., AS layer 140) of a user equipment (e.g., UE 100) in an RRC connected state (hereinafter sometimes referred to as a "connected state") with a base station (e.g., gNB 200) notifies a second layer (e.g., NAS layer 150) higher than the first layer of at least one of third information indicating whether parameters related to slice-specific cell reselection have been acquired and fourth information indicating whether parameters related to a slice-specific random access channel have been acquired. Second, the second layer notifies the first layer of fifth information indicating whether the user equipment should maintain the connected state or transition to an idle state or an inactive state based on at least one of the third information and the fourth information. Third, the first layer transmits the fifth information to the base station.

[0117] This enables the NAS layer 150 to notify the gNB 200 of its desired RRC state.

[0118] (Operation example according to the third embodiment) FIG. 10 is a diagram illustrating an example of operation according to the third embodiment.

[0119] 10, in step S30, UE 100 is in a connected state with gNB 200. UE 100 is performing communication using a certain slice with gNB 200. Specifically, AS layer 140 of UE 100 establishes a PDU (Protocol Data Unit) session associated with the slice with gNB 200, and performs data communication using the PDU session.

[0120] In step S31, the AS layer 140 of the UE 100 checks whether slice-specific cell reselection parameters and / or slice-specific RACH parameters are provided by the SIB or dedicated signaling. The check may be the same as in the first embodiment (step S13 in FIG. 7).

[0121] In step S32, the AS layer 140 sends a first notification according to the confirmation result to the NAS layer 150. The first notification may also be the same as in the first embodiment (step S14 in FIG. 7). Alternatively, the AS layer 140 may send the first notification to the NAS layer 150 when there has been no data communication for a certain period of time.

[0122] In step S33, the NAS layer 150 of the UE 100 determines a desired RRC state according to the first notification. Specifically, the NAS layer 150 determines whether to maintain the connected state or transition to an idle state or an inactive state. For example, the NAS layer 150 may determine to maintain the connected state if priority access to the serving cell is not possible (e.g., if the serving cell does not support a slice-specific RACH). This is because if the AS layer 140 transitions to the idle or inactive state, it may take time to access the serving cell again. Furthermore, for example, the NAS layer 150 may transition to the idle or inactive state if priority access to the serving cell is possible (e.g., if the serving cell supports a slice-specific RACH). Furthermore, the NAS layer 150 may make the determination in response to a request from an application included in the upper layer 160. Furthermore, the NAS layer 150 may make the determination in response to a request for Quality of Service (QoS). Note that step S33 may be a second operation instead of the first operation (step S15 in FIG. 7) in the first embodiment.

[0123] In step S34, the NAS layer 150 notifies the AS layer 140 of the desired RRC state (or instruction) based on the determination result of step S33. Alternatively, the NAS layer 150 may notify the desired RRC state in response to an inquiry (or request) from the AS layer 140 when there has been no data communication for a certain period of time.

[0124] The UE 100 may detect that there has been no data communication for a certain period of time. First, when there has been no data communication for a certain period of time, the NAS layer 150 may receive a first notification from the AS layer 140 (step S32), determine the RRC state (step S33), and notify the NAS layer 150 of a request (or instruction) (step S34). Second, when there has been no data for a certain period of time, the AS layer 140 may inquire of the NAS layer 150 in step S35 whether or not the RRC state can be transitioned (to an idle state or an inactive state). In this case, in step S36, the NAS layer 150 may notify the NAS layer 150 of a request (or instruction) based on the determination result in response to the inquiry.

[0125] Alternatively, the UE 100 may make the inquiry in step S35 immediately before step S37. That is, the AS layer 140 may make the inquiry before transmitting a UE Assistance Information message (or before generating the message, or when generating the message). This is because the AS layer 140 can share information with the NAS layer 150 and then transmit the UE Assistance Information message. The AS layer 140 may notify the NAS layer 150 of information indicating whether the serving cell provides slice-specific cell reselection parameters and / or slice-specific RACH parameters by including the information in the inquiry (or together with the inquiry). In response to receiving the inquiry, the NAS layer 150 may newly determine a transition of the RRC state. In step S36, the NAS layer 150 notifies the AS layer 140 of the desired RRC state.

[0126] In step S37, the AS layer 140 generates a UE assistance information message, which includes information according to a request (or instruction) from the NAS layer 150.

[0127] Specifically, the AS layer 140 sets the RRC state desired by the UE 100 to "ReleasePreference," an IE in the UE Assistance Information message. That is, if the preference indicates that the UE 100 should remain in the connected state, the AS layer 140 sets "preferredRRC-State" to "connected." If the preference indicates that the UE 100 should transition to the idle state, the AS layer 140 sets "preferredRRC-State" to "idle." If the preference indicates that the UE 100 should transition to the inactive state, the AS layer 140 sets "preferredRRC-State" to "inactive." The AS layer 140 may transition to the idle state. If the AS layer 140 may transition to the inactive state, the AS layer 140 sets "preferredRRC-State" to "outOfConnected." The transition to the idle state or the inactive state may be set according to the preference of the AS layer 140. In this case, the AS layer 140 may, depending on the preference, set the "preferredRRC-State" to "connected".

[0128] In step S38, the AS layer 140 transmits the generated UE assistance information to the gNB 200. This makes it possible for the NAS layer 150 to notify the gNB 200 of the RRC state of the UE 100 desired.

[0129] [Fourth embodiment] Next, a fourth embodiment will be described.

[0130] When slice-specific cell reselection is completed, it may be considered that UE 100 has moved to the optimal cell (or frequency) that supports the "intended slice." In such a case, AS layer 140 notifies NAS layer 150 that UE 100 has moved to the optimal cell, which enables NAS layer 150 to perform various processes. Conversely, UE 100 may fail slice-specific cell reselection. AS layer 140 notifies NAS layer 150 of the failure, which enables NAS layer 150 to perform various processes.

[0131] Therefore, in the fourth embodiment, when the AS layer 140 of the UE 100 in the idle state or inactive state completes the slice-specific cell reselection, it notifies the NAS layer 150 of the completion notification.

[0132] Specifically, first, a first layer (e.g., AS layer 140) of a user equipment (e.g., UE 100) in an RRC idle state or an RRC inactive state performs slice-specific cell reselection. Second, when the first layer completes the slice-specific cell reselection, it notifies a second layer (e.g., NAS layer 150) above the first layer of a completion notification.

[0133] (Operation example according to the fourth embodiment) FIG. 11 is a diagram illustrating an example of operation according to the fourth embodiment.

[0134] As shown in FIG. 11, in step S40, the UE 100 is in an idle state or an inactive state.

[0135] In step S41, the NAS layer 150 of the UE 100 notifies the AS layer 140 of the "intended slice".

[0136] In step S42, the AS layer 140 of the UE 100 acquires slice-specific cell reselection parameters from a cell before cell reselection (for example, a first cell). The AS layer 140 may acquire the parameters through an SIB or dedicated signaling.

[0137] In step S43, the AS layer 140 performs slice-specific cell reselection using slice-specific cell reselection parameters.

[0138] In step S44, the AS layer 140 checks the completion condition of the slice-specific cell reselection. The completion condition of the slice-specific cell reselection is one of the following three conditions.

[0139] (B1) When the slice-specific cell reselection process is completed after the AS layer 140 applies slice-specific cell reselection parameters (or while applying the parameters), that is, when the AS layer 140 reselects a prioritized frequency (or cell) associated with the slice.

[0140] (B2) When the AS layer 140 reselects the highest priority frequency (or cell) notified in the slice-specific cell reselection parameter. Instead of the "highest priority," the frequency (or cell) may be a "high priority" frequency (or cell). In this case, the number of frequencies that are "high priority" among the frequencies assigned with priority may be set by the gNB 200.

[0141] (B3) When the cell (or frequency) reselected by the AS layer 140 transmits slice-specific RACH parameters corresponding to a slice identifier indicating an "intended slice." For example, this is when the UE 100 receives slice-specific RACH parameters for the slice it wants to use from the reselected cell.

[0142] In the above (B1) to (B3), "reselecting a frequency" means, for example, that the AS layer 140 reselects a cell (for example, a suitable cell) belonging to a frequency (for example, a frequency with the highest priority) notified in the slice-specific cell reselection parameters. Also, "reselecting a cell" means, for example, that the AS layer 140 selects a suitable cell in a frequency (for example, a frequency with the highest priority) notified in the slice-specific cell reselection parameters. In addition, "reselecting a cell" may mean reselecting a cell notified in the slice-specific cell reselection parameters (for example, a cell with the highest priority or a cell with a cell-specific offset value set). The cell-specific offset value is an offset value (for example, "RSRP + offset value (dB)") that is added to a radio measurement value (such as RSRP (Reference Signal Received Power)) when evaluating a suitable cell or a best ranked cell, and a different offset value is set for each cell (or is not set for some cells).

[0143] If all of the completion conditions (B1) to (B3) are not satisfied, the AS layer 140 may determine that the slice-specific cell reselection has failed. In this case, the AS layer 140 may perform normal cell reselection instead of slice-specific cell reselection.

[0144] In step S45, the AS layer 140 sends a fourth notification to the NAS layer 150. Here, there are two cases for the fourth notification: one where any one of the completion conditions (B1) to (B3) is satisfied, and one where none of the completion conditions is satisfied.

[0145] (If any of the completion conditions are met) If any of the completion conditions is met (if the slice-specific cell reselection is successful), the AS layer 140 notifies a fourth notification including any of the following information:

[0146] (C1) Slice-specific cell reselection is complete.

[0147] (C2) The cell is in coverage area of ​​a cell that supports the slice in question (the "intended slice").

[0148] (C3) The UE 100 is present in a cell that supports prioritized access to the slice (“intended slice”). For example, the UE 100 is present in the cell that transmits slice-specific RACH parameters.

[0149] (If the completion conditions are not met) If all of the completion conditions are not satisfied, the AS layer 140 notifies a fourth notification including any of the following information. Note that a case where all of the completion conditions are not satisfied means a case where slice-specific cell reselection has failed and / or a case where normal cell reselection has been performed. A case where normal cell reselection has been performed also includes a case where normal cell reselection has been successful or has been completed.

[0150] (D1) Failure of slice-specific cell reselection.

[0151] (D2) The device is located in a cell that may not support the slice in question (the "intended slice").

[0152] (D3) The UE 100 is present in a cell that does not support prioritized access to the slice (“intended slice”). For example, the UE 100 is present in the cell that does not transmit slice-specific RACH parameters.

[0153] In step S46, the NAS layer 150 performs a third operation in response to the fourth notification. The third operation may be, for example, one of the following three operations.

[0154] First, as a third operation, the NAS layer 150 may establish or modify a PDU session corresponding to the slice ("intended slice"). For example, when URLLC slice is supported in the serving cell, the NAS layer 150 may establish a PDU session corresponding to the slice and start communication for the URLLC slice. Alternatively, for example, the NAS layer 150 may include information about the slice ("intended slice") in a Requested S-NSSAI and send a PDU Session Request message or a PDU Session Modification message to the AMF 301. The NAS layer 150 may also send a handover request or a redirection request to the AMF 301.

[0155] Second, as a third operation, the NAS layer 150 may notify an application in the upper layer 160. For example, the NAS layer 150 may notify the URLLC application of permission to communicate or that communication is possible. Alternatively, for example, the NAS layer 150 may notify the user interface of the URLLC application to display that the communication service is within the service area, or may notify the URLLC application to start URLLC communication.

[0156] Third, the NAS layer 150 may request (or instruct) the AS layer 140 to establish an RRC connection.

[0157] (Modification of the fourth embodiment) In the fourth embodiment, a case where slice-specific cell reselection is completed has been described. For example, instead of slice-specific cell reselection, slice-specific cell selection may be completed. Alternatively, PLMN selection may be performed to select a PLMN. Alternatively, NPN (Non Public Network) selection may be performed to select a non-public network such as local 5G.

[0158] [Other embodiments] A program may be provided that causes a computer to execute each process performed by the UE 100 or the gNB 200. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0159] In addition, 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).

[0160] As used in this disclosure, the terms "based on" and "depending on" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "based only on" and "at least in part on." Furthermore, "obtain" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating the information. The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may also mean including only the listed items or including additional items in addition to the listed items. Furthermore, as used in this disclosure, the term "or" is not intended to mean an exclusive or. Furthermore, any reference to 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, reference to first and second elements does not imply that only two elements may be employed therein or that the first element must precede the second element in some manner. 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.

[0161] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes can be made within the scope of the present invention. Furthermore, it is also possible to combine all or part of each embodiment within a consistent scope. For example, the PDU change operation in the NAS layer 150 and the handover request and redirection request in the NAS layer 150 described in the fourth embodiment can also be performed in the second embodiment.

[0162] This application claims priority to Japanese Patent Application No. 2021-128836 (filed August 5, 2021), the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0163] 1: Mobile communication system 10:5GC 100:UE 110: Receiving section 130: Control unit 140: AS layer 150: NAS layer 160: Upper layer 200:gNB 210: Transmitter 220: Receiving section 230: Control unit 301:AMF 302:UPF

Claims

1. A communication control method in a mobile communication system having a user equipment and a network node, wherein wireless communication is possible between the user equipment and the network node, comprising: Notifying a second layer higher than the first layer of at least one of first information indicating whether a first layer of the user equipment in an RRC connected state with the network node has acquired parameters related to slice-specific cell reselection and second information indicating whether a first layer of the user equipment has acquired parameters related to a slice-specific random access channel; The second layer of the user equipment notifies the first layer of third information indicating whether the user equipment should maintain the RRC connected state or transition to an RRC idle state or an RRC inactive state based on at least one of the first information and the second information; and the first layer transmitting the third information to the network node. Communication control method.

2. the transmitting step includes the first layer transmitting a UE Assistance Information message including the third information to the network node. The communication control method according to claim 1.

3. a user device; a network node that wirelessly communicates with the user equipment; The user equipment includes a transceiver circuit and a processing circuit operatively associated with the transceiver circuit, the processing circuit comprising: A process of notifying a second layer higher than the first layer of at least one of first information indicating whether or not parameters related to slice-specific cell reselection have been acquired and second information indicating whether or not parameters related to a slice-specific random access channel have been acquired from a first layer of the user equipment in an RRC connected state with the network node; The second layer of the user equipment notifies the first layer of third information indicating whether the user equipment should maintain the RRC connected state or transition to an RRC idle state or an RRC inactive state based on at least one of the first information and the second information; the first layer performs a process of transmitting the third information to the network node. Mobile communication system.

4. A user equipment that wirelessly communicates with a network node, A transmitter / receiver circuit and a processing circuit operatively associated with the transmitter / receiver circuit, the processing circuit comprising: A process of notifying a second layer higher than the first layer of at least one of first information indicating whether a first layer of the user equipment in an RRC connected state with the network node has acquired parameters related to slice-specific cell reselection and second information indicating whether a first layer of the user equipment has acquired parameters related to a slice-specific random access channel; The second layer of the user equipment notifies the first layer of third information indicating whether the user equipment should maintain the RRC connected state or transition to an RRC idle state or an RRC inactive state based on at least one of the first information and the second information; the first layer performs a process of transmitting the third information to the network node. User equipment.

5. A program for controlling a user device that performs wireless communication with a network node, A process of notifying a second layer higher than the first layer of at least one of first information indicating whether a first layer of the user equipment in an RRC connected state with the network node has acquired parameters related to slice-specific cell reselection and second information indicating whether a first layer of the user equipment has acquired parameters related to a slice-specific random access channel; The second layer of the user equipment notifies the first layer of third information indicating whether the user equipment should maintain the RRC connected state or transition to an RRC idle state or an RRC inactive state based on at least one of the first information and the second information; the first layer causes the user equipment to perform a process of transmitting the third information to the network node. program.

6. A chipset for controlling a user device that wirelessly communicates with a network node, A process of notifying a second layer higher than the first layer of at least one of first information indicating whether a first layer of the user equipment in an RRC connected state with the network node has acquired parameters related to slice-specific cell reselection and second information indicating whether a first layer of the user equipment has acquired parameters related to a slice-specific random access channel; The second layer of the user equipment notifies the first layer of third information indicating whether the user equipment should maintain the RRC connected state or transition to an RRC idle state or an RRC inactive state based on at least one of the first information and the second information; the first layer performs a process of transmitting the third information to the network node. Chipset.

Images