Communication control method, user equipment, and processor

Abstract

A communication control method according to one embodiment of the present application is for a mobile communication system that has a user equipment and a base station apparatus and that implements wireless communication between the user equipment and the base station apparatus. In the communication control method, a first layer of the user equipment acquires slice information of a cell in which the user equipment exists, the slice information having been transmitted from the base station apparatus, and the first layer of the user equipment reports the slice information to a second layer of the user equipment, the second layer being a higher layer than the first layer.

Description

TECHNICAL FIELD

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

[0002] In standards of the Third Generation Partnership Project (3GPP), which is a standardization project for mobile communication systems, network slicing (or network slice) has been defined (for example, see Non-Patent Literature 1).

[0003] Network slicing is a concept that allows differentiated handling according to each customer requirement. Network slicing is also a technology for virtually slicing a network in order to efficiently provide a network according to the requirements of services used by customers.

[0004] Network slicing is composed of parts of a radio access network (RAN) and a core network (CN). Each network slice is identified by single network slice selection assistance information (S-NSSAI).

[0005] For example, network slicing can be constructed for each service such as enhanced mobile broadband (eMBB: high speed and large capacity). This allows, for example, a network to provide a network slice that matches each service to a user.

[0006] Note that, in the 3GPP, a technology is being studied in which a plurality of different slices can be supported under different frequencies, and a plurality of different slices can be supported under the same frequency in different areas (for example, see Non-Patent Literature 2).

[0007] List of Citations

[0008] Non-Patent Literature

[0009] Non-Patent Literature 1: 3GPP TS 38.300 V16.2.0 (2020-07)

[0010] Non-Patent Literature 2: 3GPP TR 38.832 V0.1.0 (2020-08) SUMMARY

[0011] In the first embodiment, the communication control method is a communication control method used in a mobile communication system including a user equipment and a base station apparatus, and configured to perform wireless communication between the user equipment and the base station apparatus. The communication control method includes: acquiring, by a first layer of the user equipment, slice information of a cell in which the user equipment exists, the slice information being transmitted from the base station apparatus; and notifying, by the first layer of the user equipment, the slice information to a second layer of the user equipment, the second layer being higher than the first layer.

[0012] In a second embodiment, a communication control method is a communication control method used in a mobile communication system including a user equipment and a base station apparatus, and configured to perform wireless communication between the user equipment and the base station apparatus. The communication control method includes: notifying, by a second layer of the user equipment, a first layer of the user equipment of an expected slice, the second layer being higher than the first layer; and performing, by the first layer of the user equipment, a predetermined process.

[0013] In a third embodiment, a communication control method is a communication control method used in a mobile communication system including a user equipment and first and second base station apparatuses, and configured to perform wireless communication between the user equipment and the first and second base station apparatuses. The communication control method includes: broadcasting, by the second base station apparatus, slice information supported by a first base station apparatus adjacent to the second base station apparatus. The communication control method includes: acquiring, by the user equipment, the slice information supported by the first base station apparatus.

[0014] In a fourth embodiment, a communication control method is a communication control method used in a mobile communication system including a user equipment and a base station apparatus, and configured to perform wireless communication between the user equipment and the base station apparatus. The communication control method includes: broadcasting, by the base station apparatus, a cell reselection priority for each network slice; and performing, by the user equipment, cell reselection by using the cell reselection priority.

[0015] In a fifth embodiment, a communication control method is a communication control method used in a mobile communication system including a user equipment and a base station apparatus, and configured to perform wireless communication between the user equipment and the base station apparatus. The communication control method includes: preferentially selecting, by the user equipment, a cell supporting a network slice that the user equipment has accessed before RRC (Radio Resource Control) reestablishment, at cell selection when the user equipment performs the RRC reestablishment; and accessing, by the user equipment, the selected cell. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a diagram illustrating a configuration example of a mobile communication system according to an embodiment.

[0017] Figure 2 is a diagram illustrating a configuration example of a user equipment according to an embodiment.

[0018] Figure 3 is a diagram illustrating a configuration example of a base station apparatus according to an embodiment.

[0019] Figure 4 is a diagram illustrating a configuration example of a protocol stack of a user plane of a radio interface.

[0020] Figure 5This is a diagram illustrating an example configuration of the protocol stack for the control plane of a radio interface.

[0021] Figure 6 This is a diagram illustrating an example of the relationship between the AS layer and higher layers.

[0022] Figure 7(A) is a diagram illustrating an example of a mobile communication system, and Figure 7(B) is a diagram illustrating an operational example of Example 1.

[0023] Figures 8(A) and 8(B) are diagrams illustrating operational examples of Example 2 and Example 3, respectively.

[0024] Figure 9 This is a diagram illustrating an example of the operation in Example 4.

[0025] Figure 10(A) is a diagram illustrating an operational example of Example 5, and Figure 10(B) is a diagram illustrating an example of sending slice information.

[0026] Figure 11 This is a diagram illustrating an example of sending slice information.

[0027] Figures 12(A) and 12(B) are diagrams showing operational examples of Example 6 and Example 7, respectively.

[0028] Figure 13 This is a diagram illustrating an example of operation from Example 8.

[0029] Figure 14 This is a diagram illustrating an example of operation from Example 9. Detailed Implementation

[0030] A mobile communication system is described with reference to the accompanying drawings, according to an embodiment. In the description of the drawings, identical or similar parts are indicated by identical or similar reference numerals.

[0031] Configuration of mobile communication system

[0032] First, in the embodiments, a configuration example of the mobile communication system is described. Although the mobile communication system in the embodiments is a 3GPP 5G system, Long Term Evolution (LTE) can be applied at least partially to the mobile communication system. Application to future wireless communication systems such as 6G is also possible.

[0033] Figure 1 This is a diagram illustrating a configuration example of a mobile communication system 1 according to an embodiment.

[0034] like Figure 1 As shown, the mobile communication system 1 includes a user equipment (UE) 100 and a 5G radio access network (NG-RAN) 10.

[0035] The UE 100 is a mobile device. The UE 100 can be any device as long as the device is used by a user. Examples of the UE 100 include a device that can perform wireless communication, such as 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, a device provided on a sensor, a vehicle, a device provided on a vehicle (a vehicle UE), a flying object, and a device provided on a flying object (an aerial UE).

[0036] The NG-RAN 10 includes base station devices (in some cases, also referred to as "base stations" hereinafter) 200-1 to 200-3 called "gNB" ("next generation Node B") in the 5G system. The gNBs 200-1 to 200-3 can also be referred to as NG-RAN nodes. The gNBs 200-1 to 200-3 are connected to each other via an Xn interface that is an inter-base station interface. Each of the gNBs 200-1 to 200-3 manages one or more cells. Each of the respective gNBs 200-1 to 200-3 performs wireless communication with the UE 100 that has established a connection with a cell of the gNB 200-1 to 200-3 itself. Each of the gNBs 200-1 to 200-3 has a radio resource management (RRM) function, a function of routing data (hereinafter simply referred to as "data"), and / or a measurement control function for mobility control and scheduling, and the like. The "cell" is used as a term representing the smallest unit of a wireless communication area. The "cell" is also used as a term representing a function or a resource for performing wireless communication with the UE 100. One cell belongs to one carrier frequency. Note that, in the present embodiment, "cell" and "base station device" or "cell" and "gNB" can be used without being distinguished from each other.

[0037] Note that the gNBs 200-1 to 200-3 can be connected to an evolved packet core (EPC) that is a core network of LTE, and / or a base station of LTE can be connected to the 5GC 20. The base station of LTE can be connected to the gNBs 200-1 to 200-3 via an inter-base station interface.

[0038] The 5GC 20 includes an access and mobility management function (AMF) and a user plane function (UPF) 300. The AMF performs various types of mobility control and the like for the UE 100. The AMF manages information of an area in which the UE 100 exists by communicating with the UE 100 using non-access stratum (NAS) signaling. The UPF controls transmission of data. The AMF and the UPF 300 are connected to the gNBs 200-1 to 200-3 via an NG interface that is an interface between a base station and a core network.

[0039] Note that in the following description, the gNBs 200-1 to 200-3 can be referred to as gNB 200. The AMF of the AMF and UPF 300 can be referred to as AMF 300.

[0040] Figure 2 is a diagram illustrating a configuration of a UE 100 (user equipment) according to an embodiment.

[0041] As Figure 2 illustrated, the UE 100 includes a receiver 110, a transmitter 120, and a controller 130.

[0042] The receiver 110 performs various types of reception under the control of the controller 130. The receiver 110 includes an antenna and a receiving device. The receiving device converts (down-converts) a radio signal received through the antenna into a baseband signal (a reception signal) and outputs the resulting signal to the controller 130.

[0043] The transmitter 120 performs various types of transmission under the control of the controller 130. The transmitter 120 includes an antenna and a transmitting device. The transmitting device converts (up-converts) a baseband signal (a transmission signal) output by the controller 130 into a radio signal and transmits the resulting signal through the antenna.

[0044] The controller 130 performs various types of control in the UE 100. The controller 130 includes at least one processor and at least one memory electrically connected to the processor. The memory stores programs to be executed by the processor, and information to be processed by the processor. The processor can include a baseband processor and a central processing unit (CPU). The baseband processor performs modulation and demodulation, encoding and decoding, and the like of a baseband signal. The CPU executes programs stored in the memory, thereby performing various types of processing. The CPU can be replaced by a processor or a controller such as a digital signal processor (DSP) or a field programmable gate array (FPGA). In the present embodiment, the controller 130 can perform various types of control or processing described in the following examples.

[0045] Figure 3 is a diagram illustrating a configuration of a gNB 200 (base station) according to an embodiment.

[0046] As Figure 3 illustrated, the gNB 200 includes a transmitter 210, a receiver 220, a controller 230, and a backhaul communicator 240.

[0047] The transmitter 210 performs various types of transmission under the control of the controller 230. The transmitter 210 includes an antenna and a transmitting device. The transmitting device converts (up-converts) a baseband signal (a transmission signal) output by the controller 230 into a radio signal and transmits the resulting signal through the antenna.

[0048] The receiver 220 performs various types of reception under the control of the controller 230. The receiver 220 includes an antenna and a receiving device. The receiving device converts (down-converts) a radio signal received through the antenna into a baseband signal (a reception signal) and outputs the resulting signal to the controller 230.

[0049] The controller 230 performs various types of control with respect to the gNB 200. The controller 230 includes at least one processor and at least one memory electrically connected to the processor. The memory stores programs to be executed by the processor and information to be processed by the processor. The baseband processor performs modulation and demodulation, encoding and decoding, and the like of a baseband signal. The CPU executes programs stored in the memory, thereby performing various types of processing. Instead of the CPU, a processor or a controller such as a DSP or an FPGA can be used. In the present embodiment, the controller 230 can perform various types of control or processing described in the following examples.

[0050] The backhaul communicator 240 is connected to neighboring base stations via an inter-base station interface. The backhaul communicator 240 is connected to each node of the 5GC 20 via an interface between the base station and the core network. Note that the gNB 200 can include a central unit (CU) and a distributed unit (DU) (i.e., functions are divided), and the two units can be connected via an F1 interface.

[0051] Protocol stack in radio interface

[0052] Figure 4 is a diagram showing a configuration of a protocol stack of a radio interface that processes a user plane of data.

[0053] As Figure 4 shown, the radio interface protocol of the user plane 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.

[0054] The PHY layer performs encoding and decoding, modulation and demodulation, antenna mapping and de-mapping, and resource mapping and de-mapping. Data and control information are transmitted and received between the PHY layers of the UE 100 and the gNB 200 via a physical channel.

[0055] The MAC layer performs priority control of data, retransmission processing using hybrid ARQ (HARQ), a random access procedure, and the like. Data and control information are transferred via a transport channel between the MAC layers of the UE 100 and the gNB 200. The MAC layer of the gNB 200 includes a scheduler. The scheduler determines the transport format (transport block size, modulation and coding scheme (MCS)) and the resource blocks to be allocated to the UE 100 in the uplink and downlink.

[0056] The RLC layer sends data to the RLC layer of the receiving side by using the functions of the MAC layer and the PHY layer. Data and control information are transferred via a logical channel between the RLC layer of the UE 100 and the RLC layer of the gNB 200.

[0057] The PDCP layer performs header compression and decompression, and encryption and decryption.

[0058] The SDAP layer performs mapping between an IP flow, which is a unit of QoS control by a core network, and a radio bearer, which is a unit of QoS control by an access stratum (AS). Note that when the RAN is connected to an EPC, the SDAP can not be provided.

[0059] Figure 5 is a diagram illustrating a configuration of a protocol stack of a radio interface that handles signaling (control signals) of a control plane. As Figure 5 indicated, the protocol stack of the radio interface of the control plane includes a radio resource control (RRC) layer and a non-access stratum (NAS) layer, instead of the SDAP layer as Figure 4 indicated.

[0060] RRC signaling for various configurations is transferred between the RRC layer of the UE 100 and the RRC layer of the gNB 200. The RRC layer controls logical, transport, and physical channels in accordance with establishment, reconstruction, and release of a radio bearer. When there is a connection (RRC connection) between the RRC of the UE 100 and the RRC of the gNB 200, the UE 100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of the UE 100 and the RRC of the gNB 200, the UE 100 is in an RRC idle state. When the RRC connection is suspended, the UE 100 is in an RRC inactive state.

[0061] The NAS layer higher than the RRC layer performs session management, mobility management, and the like. NAS signaling is transferred between the NAS layer of the UE 100 and the NAS layer of the AMF 300.

[0062] Note that the UE 100 includes an application layer other than the protocols of the radio interface.

[0063] Operation Examples

[0064] Next, operation examples are described. The operation examples are described in the following order.

[0065] (Example 1) In the UE 100, slice information of a cell in which the UE 100 exists is notified from an AS layer to a higher layer (NAS or the like).

[0066] (Example 2) In the UE 100, the higher layer notifies the AS layer of an expected slice.

[0067] (Example 3) In the UE 100, the AS layer searches for and reselects a cell that supports the expected slice notified from the higher layer.

[0068] (Example 4) The UE 100 notifies a gNB 200 of an expected slice.

[0069] (Example 5) A cell broadcasts (or notifies) slice information supported by a neighboring cell.

[0070] (Example 6) A gNB 200-1 notifies a neighboring gNB 200-2 of slice information supported by the gNB 200-1.

[0071] (Example 7) An AMF 300 notifies a gNB 200 of slice information supported by a neighboring cell.

[0072] (Example 8) A serving cell broadcasts (or notifies) a cell reselection priority for each slice.

[0073] (Example 9) In cell selection at the time of RR reestablishment, the UE 100 preferentially selects a cell supported by a slice in which the UE 100 is accessing.

[0074] Example 1

[0075] Figure 6 is a diagram illustrating an example of a relationship between an AS layer 140 and a higher layer 150 in the UE 100. As Figure 6 indicated, the UE 100 includes the AS layer 140 and the higher layer 150 above the AS layer 140.

[0076] The AS layer 140 and the higher layer 150 include Figure 5 layers of a control plane of a radio interface as indicated. In other words, the AS layer 140 includes a PHY layer, a MAC layer, an RLC layer, a PDCP layer, and an RRC layer. The higher layer 150 includes a NAS layer. In Example 1, as indicated, slice information related to a network slice of a cell in which the UE 100 exists is notified from the AS layer 140 to the higher layer 150. Such processing can be performed in the controller 130, for example. Note that, hereinafter, a network slice can be referred to as a “slice”. Figure 6 ​

[0077] FIG. 7(A) is a diagram illustrating an example in which the UE 100 exists in cell #1 of the gNB 200. In this case, the UE 100 notifies the higher layer 150 of slice information of cell #1 in which the UE 100 exists, from the AS layer 140.

[0078] The slice information is processed in the NAS layer, and is managed in, for example, the AMF 300. On the other hand, information related to a cell is processed in the AS layer 140. When the AS layer 140 in the UE 100 receives the slice information of cell #1, the AS layer 140 notifies the higher layer 150 of the slice information, so that the higher layer 150 (or the NAS layer) can grasp the slice information of each cell.

[0079] FIG. 7(B) is a diagram illustrating an example of operation in Example 1.

[0080] In step S100, the UE 100 in the idle state or inactive state acquires slice information related to a slice supported in a cell (cell #1 in the example of FIG. 7(A)) of the gNB 200 in which the UE 100 exists.

[0081] The slice information can be included in a system information block (SIB) and broadcast, or can be included in an RRC message and transmitted to the UE 100. The slice information can include S-NSSAI, or can include a human-readable identifier such as "eMBB". The UE 100 in the RRC connected state can receive the slice information.

[0082] In step S101, the AS layer 140 notifies the higher layer 150 of the slice information. Examples of a trigger for the AS layer 140 to notify the higher layer 150 include the following.

[0083] Specifically, when the UE 100 in the idle state or inactive state performs cell selection or cell reselection, the AS layer 140 can notify the higher layer 150 of the slice information. When handover is performed in the UE 100 in the RRC connected state, the AS layer 140 can notify the higher layer 150 of the slice information. The AS layer 140 can notify when slice information supported by a cell changes. The AS layer 140 can notify when previously notified slice information is different from current slice information (or current slice information acquired from the gNB 200). The AS layer 140 can periodically (or at a constant period) notify.

[0084] In step 102, the higher layer 150 performs predetermined processing. For example, the predetermined processing includes the following.

[0085] Specifically, the higher layer 150 can notify the application layer of the currently supportable slice information. In this case, the higher layer 150 can select supportable slice information from one or more pieces of slice information notified in step S101, and notify the selected slice information. The higher layer 150 (or the controller 130) can display slice coverage information on the display of the UE 100. As the slice coverage information, for example, a supported service name such as "5G URLLC" can be displayed next to an antenna mark on the display. The slice coverage information can be displayed in a setting bar. The higher layer 150 can notify the AS layer 140 of the intended slice. The above details are described in Example 2.

[0086] Example 2

[0087] Example 2 is an example in which the higher layer 150 of the UE 100 notifies the AS layer 140 of the intended slice.

[0088] The intended slice can be a slice that is expected to be used in the UE 100, a candidate slice, or a desired slice. For example, the higher layer 150 that notifies the AS layer 140 of such a slice allows the AS layer 140 to perform various processes, such as a cell reselection process.

[0089] FIG. 8(A) is a diagram illustrating an example of the operation in Example 2.

[0090] In step S110, the higher layer 150 notifies the AS layer 140 of the intended slice.

[0091] The intended slice to be notified can be in the form of a list of a plurality of intended slices. In this case, for example, there can be a plurality of slices used (or requested) by an installed or active application in the UE 100, and these slices can be in the form of a list. For example, there can be a plurality of intended slices licensed (or authenticated) by the CN, and these slices can be in the form of a list.

[0092] When there are a plurality of intended slices, a priority of each intended slice can be further notified. The higher layer 150 can instruct the AS layer 140 to search for the intended slice by using cell reselection or the like. The above details are described in Example 3. When the higher layer 150 receives a query (such as a request of an information provision request) from the AS layer 140, the higher layer 150 can notify the AS layer 140 of the intended slice. In this case, the AS layer 140 can make a query to the higher layer 150 about the intended slice, for example, at the time of cell reselection or at the time of changing slice information supported by a cell.

[0093] Note that the intended slice can be created in the higher layer 150. The intended slice can be transmitted from the AMF 300 to the higher layer 150.

[0094] In step 111, the AS layer 140 performs predetermined processing. For example, the predetermined processing includes the following.

[0095] Specifically, the AS layer 140 can check whether the notified intended slice is supported in the cell in which the UE 100 exists. In this case, the AS layer 140 can notify the NAS layer (or the higher layer 150) of "IN" if supported or "OUT" if not supported. In the UE 100 in the idle state or inactive state, when the notified intended slice is not supported in the cell in which the UE 100 exists, the AS layer 140 can perform cell reselection. The above details are described in Example 3. On the other hand, in the UE 100 in the RRC connected state, when the notified intended slice is not supported in the cell in which the UE 100 exists, the AS layer 140 can transmit the intended slice to the gNB 200. The above details are described in Example 4.

[0096] Example 3

[0097] Example 3 is an example in which, in the UE 100 in the idle state or inactive state, the AS layer 140 searches for a cell supporting the intended slice notified from the higher layer 150 and performs cell reselection.

[0098] For example, the UE 100 can access a slice providing a service desired by the UE 100 by searching for and reselecting such a cell, and receive such a service via the accessed slice.

[0099] FIG. 8(B) is a diagram illustrating an example of the operation of Example 3.

[0100] In step S120, the intended slice is notified from the higher layer 150 to the AS layer 140.

[0101] In step S121, the AS layer 140 existing in a cell not supporting the notified intended slice performs cell reselection processing.

[0102] When the cell search is instructed from the NAS layer, the AS layer 140 can perform a cell reselection process. For example, in step S120, such an instruction can be notified together with the intended slice. In the cell reselection process, the AS layer 140 can preferentially reselect (or select) a cell that supports the intended slice. In this case, for example, the AS layer 140 attempts to select a cell having the best radio quality (such as RSRP (Reference Signal Received Power)) from among cells (ranking) that support the intended slice. If such a cell does not exist, the AS layer 140 reselects a cell that does not support the intended slice. For example, the AS layer 140 performs cell reselection with the highest priority on a cell and / or a frequency that supports the intended slice. In this case, a change process can be performed on the priority of the cell or the frequency by a reselection priority process. The AS layer 140 can notify the NAS layer of whether the cell search of the intended slice was successful. In this case, for example, the AS layer 140 can notify only success or failure. For example, the AS layer 140 can notify the slice information of the cell after reselection.

[0103] Example 4

[0104] Example 4 is an example in which the UE 100 transmits the intended slice to the gNB 200. For example, the slice supported in the cell in which the UE 100 exists can not be the slice desired by the UE 100, and the UE 100 can desire another slice. In this case, the UE 100 transmits the intended slice to the gNB 200 at an appropriate timing. This allows the gNB 200 to hand over the UE 100 to a cell that supports the slice desired by the UE 100, for example, to enable the UE 100 to receive the desired service. Note that, as an example of the predetermined process in Example 2 (step S111 in FIG. 8(A)), the UE 100 can transmit the intended slice to the gNB 200.

[0105] Figure 9 FIG. 9 is a diagram illustrating an operation example of Example 4.

[0106] In step S130, the UE 100 in the RRC connected state with the gNB 200 transmits the intended slice to the gNB 200. For example, the trigger for transmitting the intended slice can be the following.

[0107] In particular, when the AS layer 140 of the UE 100 receives a notification of an expected slice from the higher layer 150, the UE 100 (or the AS layer 140) can transmit the expected slice to the gNB 200. The UE 100 can transmit the expected slice to the gNB 200 when the slice to which the UE 100 accesses is changed (or has been changed). The UE 100 can transmit the expected slice to the gNB 200 when the expected slice is changed. The situation indicated by the phrase "when the expected slice is changed" includes, for example, when initial connection of the RRC connection occurs, or when the contents of the notification of the expected slice are last transmitted. The UE 100 can transmit the expected slice to the gNB 200 when the UE 100 is provided with information from the gNB 200 (or receives a query), for example, when the UE 100 receives a request from the gNB 200. The UE 100 can transmit the expected slice to the gNB 200 when handover is predicted (or performed), for example, when a measurement report is triggered. The notification can be made if the gNB 200 pre-grants (configures) the notification.

[0108] However, for example, these transmission triggers can have the following limitations. In particular, the UE 100 can transmit the expected slice to the gNB 200 only when the slice supported by the cell (in which the UE 100 exists) does not match the expected slice (or when the UE 100 expects a slice that is not supported). In this case, for example, the expected slice can be transmitted to prompt the gNB 200 to perform handover to a cell that supports the slice expected by the UE 100. The UE 100 can transmit the expected slice to the gNB 200 only when the slice supported by the cell matches the expected slice (or supports all expected slices). In this case, for example, the expected slice can be transmitted to the gNB 200 when the UE 100 enters (or selects or hands over to) a cell that supports the desired slice.

[0109] For example, the contents of the message transmitted in step S130 can be the following contents. In particular, the UE 100 can transmit slice information indicating the expected slice in the form of a list to the gNB 200. Such slice information can include all expected slices in the UE 100 and can be transmitted. The slice information can include only the expected slice that matches the slice supported by the cell, or can include only the expected slice that does not match the slice supported by the cell.

[0110] For example, the message for transmission in step S130 can be the following. Specifically, the UE 100 can include the intended slice in the UE assistance information message to be transmitted to the gNB 200. In this case, the UE 100 can include information such as the intended slice (list), the priority (or whether prioritization is desired), and whether (provisionally in the future) to access the slice (or intended slice) for a certain period in the UE assistance information to be transmitted. The UE 100 can include the intended slice in the measurement report message to be transmitted to the gNB 200. In this case, the UE 100 can transmit the measurement report message in which the measurement result of each cell is associated with the intended slice to include the slice information supported by the cell, the match (or whether it matches) with the intended slice of the UE 100, and the preference of the UE 100 (the preference indicating the desire of "targeting the cell as possible").

[0111] In step S131, the gNB 200 performs predetermined processing for the UE 100. For example, the predetermined processing can include the following.

[0112] Specifically, when the intended slice is not supported in the cell in which the UE 100 exists, the gNB 200 can handover the UE 100 to a cell supporting the intended slice. For example, such handover allows the UE 100 to receive the desired service from the cell supporting the intended slice. The gNB 200 can transmit information indicating that the intended slice is not supported in the area (or cell) to the UE 100. In this case, when the intended slice is not supported in any neighboring cell, this can be transmitted by the gNB 200 to the UE 100.

[0113] Example 5

[0114] Example 5 is an example in which the cell broadcasts or transmits the slice information supported by the neighboring cell.

[0115] For example, when performing the cell reselection described in Example 3 or the like, the UE 100 can search for a cell and read an SIB or the like on all supported frequencies to confirm the slice supported for each cell. In this case, the UE 100 confirms the slice supported for each cell, and thus the power consumption increases.

[0116] For example, the gNB 200 broadcasts the slice information of the neighboring cell. This allows the UE 100 to acquire the slice information of the neighboring cell, which eliminates the processing of confirming the slice of the neighboring cell at the time of cell search, thereby reducing the power consumption.

[0117] FIG. 10(A) is a diagram illustrating an operation example of Example 5.

[0118] In step S140, the gNB 200 (including the serving cell of the UE 100) broadcasts the slice information supported by the neighboring cell.

[0119] FIG. 10(B) and Figure 11 are diagrams each showing an example of a relationship between a serving cell and a neighboring cell. In FIG. 10(B), the UE 100 exists in cell #1 of the gNB 200, and cell #1 is a serving cell. In this case, the gNB 200 broadcasts slice information supported by cell #2 that is adjacent to cell #1. In Figure 11 In FIG. 10(C), cell #1 of the gNB 200-1 is a serving cell of the UE 100, and cell #2 of the gNB 200-2 that is adjacent to the gNB 200-1 is a neighboring cell in the vicinity of cell #1. The gNB 200-1 broadcasts slice information of cell #2 of the gNB 200-1.

[0120] Note that, when CA (Carrier Aggregation) or DC (Dual Connectivity) is not configured, a primary cell is a serving cell for the UE 100 in an RRC connected state. When CA or DC is configured, a serving cell is used for the UE 100 in an RRC connected state in order to express a group of cells including a specific cell and all secondary cells.

[0121] The gNB 200 broadcasts slice information using a SIB. However, the gNB 200 can also transmit slice information supported by a neighboring cell through dedicated signaling. An example of the dedicated signaling can include an RRC reconfiguration message used at an RRC connection change. The gNB 200 can broadcast supported slice information in association with a cell ID (identity) (and / or a gNB ID). The gNB 200 can broadcast slice information in association with information on a guaranteed service requirement. For example, examples of the service requirement information can include the following.

[0122] Specifically, for eMBB, the service requirement information is a maximum and / or average throughput (or bit rate), and the like. For URLLC (Ultra-Reliable and Low-Latency Communication), the service requirement information is a maximum latency, a maximum packet loss, or a synchronization (or reference) clock accuracy, and the like. For mMTC (Massive Machine Type Communication), the service requirement information is a maximum number of connections, a remaining capacity (a number of remaining connections allowed), and the like. The service requirement information can be indicated by supported 5QI (5G QoS (Quality of Service) Indicator) (or QoS information). For example, the service requirement information can be information of a service requirement indicated by 5QI on which of the highest QoS levels is supportable and which of the highest QoS bearers is supportable.

[0123] Referring back to FIG. 10(A), in step S141, the UE 100 acquires slice information of a neighboring cell and performs predetermined processing. For example, the predetermined processing can include the following.

[0124] Specifically, the UE 100 can perform the cell reselection process described in Example 3. The UE 100 can notify the gNB 200. When the AS layer 140 in the UE 100 reselects a cell that does not support an intended slice, the AS layer 140 can notify the higher layer 150 of slice information of the neighboring cell. In this case, for example, the higher layer (application layer or the like) 150 can display a warning that the slice is out of coverage on a display (to the user).

[0125] Example 6

[0126] Example 6 is an example in which the gNB 200-1 transmits slice information supported by the gNB 200-1 to the neighboring gNB 200-2.

[0127] Example 5 describes an example in which the serving cell (or gNB 200) performs broadcasting or the like of slice information of a neighboring cell. The gNB 200-1 transmits slice information supported by the gNB 200-1 to the neighboring gNB 200-2. This allows the neighboring gNB 200-2 to perform broadcasting or the like including slice information of the gNB 200-1 with respect to the neighboring cell of the gNB 200-2. The UE 100 can acquire the slice information of the gNB 200-1 from the gNB 200-2.

[0128] FIG. 12(A) is a diagram showing an operation example of Example 6.

[0129] In step S150, the gNB 200-1 transmits slice information supported by the gNB 200-1 to the neighboring gNB 200-2.

[0130] In this case, the gNB 200-1 can transmit slice information associated with each cell managed by the gNB 200-1 to the neighboring gNB 200-2. The gNB 200-1 can transmit to the neighboring gNB 200-2 through Xn-AP (application protocol) signaling (or through a message of the Xn-AP). The Xn-AP is an application protocol in the control plane in the inter-base station Xn interface. The gNB 200-1 can transmit the slice information to the neighboring gNB 200-2 by the following triggers.

[0131] Specifically, when the Xn connection is established, the gNB 200-1 can transmit the slice information to the neighboring gNB 200-2. When the supported slice changes (or when the configuration of the gNB 200-1 changes), the gNB 200-1 can transmit the slice information to the neighboring gNB 200-2. When the gNB 200-1 receives a request to provide the slice information from the neighboring cell (or the neighboring gNB 200-2), the gNB 200-1 can transmit the slice information to the neighboring gNB 200-2. The gNB 200-1 can periodically (or at a constant period) transmit the slice information to the neighboring gNB 200-2.

[0132] In step S151, the gNB 200-1 performs predetermined processing in consideration of the slice information. As the predetermined processing, for example, the slice information of the neighboring cell can be updated, or mobility control can be performed. Examples of the mobility control include the handover processing of the UE 100 described above.

[0133] Example 7

[0134] Example 7 is an example in which the AMF 300 transmits the slice information supported by the neighboring cell to the gNB 200.

[0135] Example 6 or other examples describe acquiring the slice information supported by the neighboring cell from the neighboring gNB 200-1. Example 7 describes an example of acquisition by the gNB 200 from the AMF 300. This allows the gNB 200 to perform the broadcast of the slice information supported by the neighboring cell described in Example 5, for example.

[0136] FIG. 12(B) is a diagram illustrating an example of the operation of Example 7.

[0137] In step S160, the AMF 300 transmits the slice information supported by the (neighboring) gNB 200-2 subordinate to the AMF 300 to the gNB 200-1 subordinate to the AMF 300. In Figure 11 In the example of FIG. 12(A), the cell #2 of the gNB 200-2 is a "neighboring cell" of the cell #1 of the gNB 200-1. In this case, the AMF 300 transmits the slice information supported by the cell #2 (or the gNB 200-2) to the gNB 200-1.

[0138] The AMF 300 can transmit the slice information of the neighboring cell to the gNB 200 through NG-AP signaling (or through a message of the NG-AP). The trigger for the AMF 300 to transmit the slice information can be the same as the trigger for the gNB 200-1 to transmit the slice information in Example 6. In other words, the AMF 300 can transmit the slice information at the time of NG connection establishment, at the time of a change in a slice supported by the gNB 200 subordinate to the AMF 300, at the time of receiving a request for providing the slice information from the neighboring gNB 200-2 subordinate to the AMF 300, or can be transmitted periodically.

[0139] Note that the AMF 300 can be configured with the slice information supported by the neighboring cell through, for example, an operation administration and maintenance (OAM).

[0140] In step S161, the gNB 200 performs predetermined processing. The predetermined processing can be the same as the predetermined processing performed by the neighboring gNB 200-2 that receives the slice information described in Example 6. In other words, the gNB 200 can update the slice information supported by the neighboring cell, or can perform mobility control such as handover processing of the UE 100. The AMF 300 can notify the gNB 200 of the slice information supported by the AMF 300 itself (or a network managed by the AMF 300 itself). This allows the gNB 200 to appropriately select the AMF 300 (or a core network) that supports an intended slice of the UE 100 (or perform data routing of the UE 100).

[0141] Example 8

[0142] Example 8 is an example of broadcasting or transmitting the cell reselection priority for each (intended) slice.

[0143] The UE 100 performs cell reselection in accordance with the cell reselection priority configured by the cell. However, this can not allow the UE 100 to reliably select a cell that supports an intended slice.

[0144] On the other hand, it is also possible to control the selection of a cell that supports an intended slice in accordance with a dedicated priority (configured through RRC). However, when the UE 100 moves to another area (or cell) or when an intended slice of the UE 100 changes, the UE 100 can also disadvantageously not select a cell that supports the intended slice.

[0145] It is also conceivable that the UE 100 can perform cell reselection with the highest priority on a cell or a frequency that supports an intended slice. However, in this case, which cell is selected depends on the implementation of the UE 100. Therefore, control from the network side is not possible.

[0146] The gNB 200 performs broadcasting of the cell reselection priority per slice, etc. This allows the UE 100 to perform cell reselection using the cell reselection priority specified by the network side, for example. Thus, it is possible to achieve access to a cell supporting the intended slice of the UE 100 while achieving network control.

[0147] Figure 13 FIG. 8 is a diagram illustrating an operation example of Example 8.

[0148] In step S170, the gNB 200 broadcasts or transmits the cell reselection priority per slice. The gNB 200 can broadcast the cell reselection priority per slice using the SIB. The gNB 200 can transmit the cell reselection priority per slice to the UE 100 through dedicated signaling such as the RRC Release message.

[0149] The gNB 200 can broadcast the slice information described in Example 6 in association with (or in conjunction with) the cell reselection priority (or priority information) of the cell and / or the frequency. For example, in the case of the frequency priority, the UE 100 intended for (or expecting) the eMBB slice can use the priority "7" for the frequency fl, the priority "3" for the frequency f2, and so on, and the UE 100 intended for (or expecting) the URLLC slice can use the priority "7" for the frequency f2, the priority "3" for the frequency fl, and so on. For example, in the case of the cell priority, the UE 100 intended for (or expecting) the eMBB slice can use the priority "7" for the cell #1, the priority "3" for the cell #2, and so on. In these examples, the larger the number, the higher the priority, but the case where the smaller the number, the higher the priority is also possible.

[0150] Note that the gNB 200 can also broadcast the (related art) cell reselection priority not associated with the slice information. In this case, the reselection priority to be broadcasted can be used in the legacy UE (such as in Rel-15 in 3GPP) or the UE 100 not having the intended slice.

[0151] In step S171, the UE 100 applies the cell reselection priority according to the intended slice of the UE 100 and performs cell reselection. In this case, the AS layer 140 of the UE 100 can select the cell reselection priority to be applied from the broadcasted cell reselection priority by using the intended slice notified from the higher layer 150. In this case, when there are a plurality of intended slices, the AS layer 140 can select the cell reselection priority corresponding to the intended slice having the highest slice priority notified from the higher layer 150.

[0152] Example 9

[0153] Example 9 is an example in which the UE 100 prioritizes selection of a cell supporting a slice that the UE 100 is accessing at the time of RRC reestablishment.

[0154] When a radio link failure (RLF) occurs while the UE 100 in the RRC connected state is accessing a slice, the UE 100 performs an RRC reestablishment procedure. In the RRC reestablishment procedure, cell selection is performed. At the time of cell selection, if the UE 100 selects a cell that does not support a slice that the UE 100 has accessed before the RRC reestablishment, disconnection of access to the slice can occur.

[0155] In Example 9, the UE 100 prioritizes selection of a cell supporting a slice that the UE 100 has accessed before the RRC reestablishment at the time of cell selection, thereby reducing occurrence of disconnection of access to the slice. The UE 100 is allowed to receive continuous service provision.

[0156] Figure 14 FIG. 10 is a diagram illustrating an operation example of Example 9.

[0157] In step S180, the UE 100 and the gNB 200 are connected to each other in the RRC connection to be in the RRC connected state.

[0158] In step S181, the UE 100 and the gNB 200 perform data communication.

[0159] In step S182, a failure occurs in the radio link.

[0160] In step S183, the UE 100 starts an RRC reestablishment procedure to transmit an RRC reestablishment request message to the gNB 200.

[0161] In step S184, the UE 100 performs a cell selection process. The UE 100 performs cell selection using the RRC reestablishment as a trigger. In this case, the UE 100 prioritizes selection of a cell supporting a slice that the UE 100 has accessed before the RRC reestablishment. In other words, the UE 100 can be allowed to prioritize (or select) a cell supporting a slice that the UE 100 accesses. The UE 100 can perform the cell selection process based on an expected slice notified from the higher layer 150. The UE 100 can perform the cell selection process by using slice information of neighboring cells provided from a (old) serving cell (e.g., Example 5). The UE 100 can acquire slice information provided by a SIB to check slice information supported for each neighboring cell at the time of cell search.

[0162] In step S185, the UE 100 receives the RRC reestablishment request message.

[0163] In step S186, the UE 100 transmits an RRC reestablishment complete message.

[0164] In step S187, the UE 100 establishes an RRC connection with the cell selected in step S184 (the gNB 200 having the cell).

[0165] In step S188, the UE 100 accesses the selected cell (the gNB 200 having the selected cell) and performs data communication with the cell. The UE 100 can continuously access the slice that the UE 100 has accessed before the radio link failure (step S182), and can receive a continuous service provision through the slice.

[0166] Other Embodiments

[0167] A program that causes a computer to execute each process performed by the UE 100 or the gNB 200 can be provided. The program can be recorded in a computer-readable medium. The use of the computer-readable medium enables the program to be installed on a computer. Here, the computer-readable medium on which the program is recorded can be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and can be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0168] Circuitry for executing the processing to be performed by the UE 100 or the gNB 200 can be integrated, and at least a part of the UE 100 or the gNB 200 can be configured as a semiconductor integrated circuit (chipset or SoC).

[0169] Although the embodiments have been described in detail with reference to the accompanying drawings, the specific configurations are not limited to the above-described configurations, and various design modifications and the like can be made without departing from the gist. All or part of the examples can be combined together as long as the combination remains consistent.

[0170] This application claims priority to Japanese Patent Application No. 2020-171978 (filed on October 12, 2020), the contents of which are incorporated herein by reference in their entirety.

[0171] List of Reference Signs

[0172] 1: Mobile communication system

[0173] 10: NG-RAN

[0174] 20: 5GC

[0175] 100: UE

[0176] 110: Receiver

[0177] 120: Transmitter

[0178] 130: controller

[0179] 140: AS layer

[0180] 150: higher layer 200 (200-1 to 200-3): gNB 210: transmitter

[0181] 220: receiver

[0182] 230: controller

[0183] 240: backhaul communicator 300: AMF

Claims

1. A communication control method, comprising: The base station device broadcasts system information, which indicates the cell reselection priority for each network slice; The user equipment receives slice information from the core network equipment. The slice information includes information identifying multiple network slices and information indicating the slice priority of each of the multiple network slices. as well as The user equipment performs cell reselection by using the cell reselection priority of each network slice received from the base station device and the slice information received from the core network device.

2. The communication control method according to claim 1 further includes: For the frequency of the network slice with the highest slice priority indicated by the slice information, the user equipment applies the cell reselection priority corresponding to the network slice indicated by the system information.

3. The communication control method according to claim 2 further includes: The base station broadcasts first information, which indicates the cell reselection priority that does not correspond to the network slice; as well as For frequencies that do not support the network slices indicated by the slice information, the user equipment applies the cell reselection priority indicated by the first information.

4. A user equipment, comprising: The receiver receives system information from the base station device, the system information indicating the cell reselection priority for each network slice; as well as The controller performs cell reselection. The receiver receives slice information from the core network equipment. The slice information includes information identifying multiple network slices and information indicating the slice priority of each of the multiple network slices. The controller performs cell reselection by using the cell reselection priority of each network slice received from the base station device and the slice information received from the core network device.

5. A processor for controlling user equipment, the processor performing the following processes: Receive system information from the base station device, the system information indicating the cell reselection priority for each network slice; Receive slice information from core network devices, the slice information including information identifying multiple network slices and information indicating the slice priority of each of the multiple network slices; as well as Cell reselection is performed using the cell reselection priority of each network slice received from the base station device and the slice information received from the core network device.

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