Communication equipment, base station, and communication method

Abstract

To make it possible to make an efficient cell re-selection in a mobile communication system including specific UE having reduced communication capability compared to general UE.MEANS FOR SOLVING THE PROBLEM: A base station 200 broadcasts, in a cell C1, system information used for UE 100 residing in the cell C1 of the base station 200 to make a cell re-selection using an adjacent cell different from the cell C1 as a candidate. The base station 200 broadcasts system information including a second adjacent cell list different from a first adjacent cell list for general UE 100A, as an adjacent cell list indicating an adjacent cell to be excluded from candidates and an adjacent cell to be made a candidate. The second adjacent cell list is an adjacent cell list for specific UE 100B having reduced communication capability compared to the general UE 100A.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to user equipment, a base station, and a cell reselection method used in a mobile communication system. [Background technology]

[0002] In recent years, the 3GPP (3rd Generation Partnership Project), a standardization project for mobile communication systems, has been considering providing specific user devices with reduced communication capabilities compared to general user devices in 5G systems (see Non-Patent Documents 1 and 2). These specific user devices are mid-range performance and price-effective user devices for IoT (Internet of Things), and may have, for example, a narrower maximum bandwidth for wireless communication or fewer receivers compared to general user devices. Receivers are sometimes referred to as receiving branches.

[0003] Because specific user devices have characteristics not found in general user devices, the number of cells that can support specific user devices may be limited. In light of these circumstances, a technology has been proposed in which a cell notifies whether or not to allow access from a specific user device by broadcasting System Information Type 1 (SIB1) (see Non-Patent Document 3). With such a technology, a specific user device that is in an RRC idle state or RRC inactive state can avoid selecting a cell that broadcasts an SIB1 indicating that access from the specific user device is not allowed during cell re-selection. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP contribution RP-210918 “Revised WID on support of reduced capability NR devices” [Non-Patent Document 2] 3GPP Technical Report TR 38.875 v17.0.0 “Study on support of reduced capability NR devices”

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology described in Non-Patent Document 3, a specific user device can know whether access to a detected cell is permitted or not only after performing measurement processing and the like on the detected cell and then acquiring and decoding the system information (SIB1) of the cell. However, when the system information indicates that access to the cell is not permitted, the specific user device needs to search for another cell again, and the processing (especially, measurement processing) performed to decode the system information becomes wasted as a result. Therefore, there is a concern that inefficient cell reselection that consumes unnecessary power may occur.

[0006] Therefore, an object of the present invention is to provide a user device, a base station, and a cell reselection method that enable efficient cell reselection in a mobile communication system including a specific user device having a reduced communication capability compared to a general user device.

Means for Solving the Problems

[0007] The user device according to the first embodiment is a user device used in a mobile communication system, and comprises a communication unit that receives system information broadcast from the base station in the cell when the user device is located in the cell of the base station, and a control unit that performs cell reselection with a different adjacent cell as a candidate based on the system information. The communication unit receives the system information, which includes a second adjacent cell list different from the first adjacent cell list for general user devices, as an adjacent cell list indicating the adjacent cell to be excluded from the candidates or the adjacent cell to be made a candidate. The second adjacent cell list is the adjacent cell list for a specific user device having reduced communication capabilities compared to the general user device.

[0008] A base station according to the second embodiment is a base station used in a mobile communication system, and includes a communication unit that broadcasts system information in the cell used by user equipment located in the base station's cell to reselect a cell by selecting a different adjacent cell as a candidate. The communication unit broadcasts the system information, which includes a second adjacent cell list different from a first adjacent cell list for general user equipment, as an adjacent cell list indicating adjacent cells to be excluded from the candidates or adjacent cells to be considered as candidates. The second adjacent cell list is an adjacent cell list for specific user equipment having reduced communication capabilities compared to the general user equipment.

[0009] The cell reselection method according to the third aspect is a cell reselection method executed by a user equipment in a mobile communication system. When the user equipment is camped on a cell of a base station, the method includes receiving system information broadcast from the base station in the cell, and performing cell reselection with an adjacent cell different from the cell as a candidate based on the system information. The receiving step includes receiving the system information including a second list of adjacent cells different from the first list of adjacent cells for general user equipment as a list of adjacent cells to be excluded from the candidates or a list of adjacent cells to be used as candidates. The second list of adjacent cells is a list of adjacent cells for a specific user equipment having a reduced communication capability compared to the general user equipment.

Effect of the Invention

[0010] According to an aspect of the present invention, it is possible to provide a user equipment, a base station, and a cell reselection method that enable efficient cell reselection in a mobile communication system including a specific user equipment having a reduced communication capability compared to a general user equipment.

Brief Description of the Drawings

[0011] [Figure 1] It is a diagram showing the configuration of a mobile communication system according to an embodiment. [Figure 2] It is a diagram showing the configuration of a UE according to an embodiment. [Figure 3] It is a diagram showing the configuration of a base station according to an embodiment. [Figure 4] It is a diagram showing an example of the configuration of a protocol stack according to an embodiment. [Figure 5] It is a diagram showing an example of the operating environment of a mobile communication system according to an embodiment. [Figure 6] It is a diagram showing an example of the operation flow of a mobile communication system according to an embodiment. [Figure 7] It is a diagram showing an example of a first system information block according to an embodiment. [Figure 8]This figure shows an example of a second system information block according to the embodiment. [Modes for carrying out the invention]

[0012] A mobile communication system according to an embodiment will be described with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0013] (System Configuration) First, the configuration of the mobile communication system 1 according to this embodiment will be described with reference to Figure 1. The mobile communication system 1 is, for example, a system that conforms to the 3GPP Technical Specification (TS). In the following, the mobile communication system 1 will be described using the 5th Generation System (5GS) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio), as an example.

[0014] The mobile communication system 1 includes a network 10 and user equipment (UE) 100 that communicates with the network 10. The network 10 includes a 5G radio access network, NG-RAN (Next Generation Radio Access Network) 20, and a 5G core network, 5GC (5G Core Network) 30.

[0015] UE100 is a device used by a user. UE100 is a mobile device such as a smartphone or other mobile phone terminal, tablet terminal, notebook PC, communication module, or communication card. UE100 may be a vehicle (e.g., car, train, etc.) or a device installed therein. UE100 may be a transport vehicle other than a vehicle (e.g., ship, airplane, etc.) or a device installed therein. UE100 may be a sensor or a device installed thereon. Note that UE100 may also be referred to by other names such as mobile station, mobile terminal, mobile device, mobile unit, subscriber station, subscriber terminal, subscriber device, subscriber unit, wireless station, wireless terminal, wireless device, wireless unit, remote station, remote terminal, remote device, or remote unit.

[0016] In this embodiment, two types of UEs are assumed for the NR UE100: a general UE100A and a specific UE100B which has reduced communication capabilities compared to the general UE100A. The general UE100A has advanced communication capabilities such as high speed and large capacity (enhanced Mobile Broadband: eMBB) and ultra-reliable and low latency communications (URLLC), which are characteristics of NR. The specific UE100B is a UE with reduced equipment cost and complexity compared to the general UE100A. The specific UE100B is a UE100 with mid-range performance and price for IoT, and for example, compared to the general UE100A, the maximum bandwidth used for wireless communication is set to be narrower and the number of receivers is smaller. The receivers are sometimes referred to as receiving branches. The specific UE is sometimes referred to as a Reduced capability NR device or RedCap UE.

[0017] Specifically, a specific UE100B may be capable of communicating at a communication speed greater than or equal to the communication speed specified in LPWA (Low Power Wide Area) standards, such as LTE Cat.1 / 1bis, LTE Cat.M1 (LTE-M), and LTE Cat.NB1 (NB-IoT). A specific UE100B may be capable of communicating with a bandwidth greater than or equal to the bandwidth specified in the LPWA standard. A specific UE100B may have a limited bandwidth used for communication compared to a Rel-15 or Rel-16 UE. For example, for FR1 (Frequency Range 1), the maximum bandwidth of a specific UE100B may be 20MHz. Also, for FR2 (Frequency Range 2), for example, the maximum bandwidth of a specific UE100B may be 100MHz. A specific UE100B may have only one receiver for receiving radio signals. A specific UE100B may be, for example, a wearable device or a sensor device.

[0018] NG-RAN20 includes multiple base stations 200. Each base station 200 manages at least one cell. A cell constitutes the smallest unit of a communication area. A single cell belongs to a single frequency (carrier frequency). The term "cell" may represent a radio communication resource, or it may represent a communication target of the UE100. Each base station 200 can conduct radio communication with UE100s located within its own cell. The base station 200 communicates with the UE100 using the RAN's protocol stack. Details of the protocol stack will be described later. The base station 200 provides NR user plane and control plane protocol terminations toward the UE100 and is connected to the 5GC30 via the NG interface. Such NR base stations 200 are sometimes referred to as gNodeB (gNB).

[0019] 5GC30 includes a core network device 300. The core network device 300 includes, for example, an AMF (Access and Mobility Management Function) and / or a UPF (User Plane Function). The AMF manages the mobility of the UE100. The UPF provides functions specifically for U-plane processing. The AMF and UPF are connected to the base station 200 via an NG interface.

[0020] In the mobile communication system 1 configured in this way, the number of cells capable of supporting a specific UE100B (i.e., cells that support a specific UE100B) may be limited. Each cell may notify whether or not to allow access from a specific UE100B using System Information Type 1 (SIB1). A specific UE100B will not select a cell that broadcasts an SIB1 indicating that it does not allow access from a specific UE100B during cell re-selection.

[0021] Here, the specific UE100B can only determine whether access to a cell is permitted or denied after performing measurement processing on the detected cell and then acquiring and decoding the cell's system information (SIB1). However, if the system information indicates that access to the cell is denied, the specific UE100B needs to search for another cell again, and the processing performed to decode the system information (especially the measurement processing) becomes wasted.

[0022] (User device configuration) Next, the configuration of the UE100 according to this embodiment will be described with reference to Figure 2. The UE100 includes a communication unit 110 and a control unit 120.

[0023] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving radio signals to and from the base station 200. The communication unit 110 has at least one receiver 111 and at least one transmitter 112. The receiver 111 and transmitter 112 may include an antenna and an RF circuit. The antenna converts a signal into radio waves and radiates the radio waves into space. The antenna also receives radio waves in space and converts the radio waves into signals. The RF circuit performs analog processing of the signals transmitted and received via the antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, and a low-pass filter, etc.

[0024] If UE100 is a general UE100A, the number of receivers 111 in the communication unit 110 may be two to four. If UE100 is a specific UE100B, the number of receivers 111 in the communication unit 110 may be one or two.

[0025] The control unit 120 performs various controls on the UE 100. The control unit 120 controls communication with the base station 200 via the communication unit 110. The operation of the UE 100, described later, may be an operation controlled by the control unit 120. The control unit 120 may include at least one program-executable processor and memory for storing the program. The processor may execute the program to perform the operation of the control unit 120. The control unit 120 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and RF circuit. This digital processing includes processing of the RAN protocol stack. The memory stores the program executed by the processor, parameters related to the program, and data related to the program. The memory may include at least one of ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), RAM (Random Access Memory), and flash memory. All or part of the memory may be contained within the processor.

[0026] In the UE100 configured in this way, the communication unit 110 receives system information broadcast from the base station 200 in a cell when the UE is within the service area of ​​the base station 200. Based on this system information, the control unit 120 performs cell reselection, selecting adjacent cells different from the current cell as candidates. The system information includes a second adjacent cell list, which is different from the first adjacent cell list for general UE100A, as an adjacent cell list indicating adjacent cells that should be excluded from the candidates for cell reselection or adjacent cells that should be considered as candidates for cell reselection. The second adjacent cell list is an adjacent cell list for a specific UE100B. As a result, if the UE100 is a specific UE100B, it can control cell reselection based on the second adjacent cell list for the specific UE100B. Therefore, the specific UE100B can determine whether an adjacent cell can be considered as a candidate for cell reselection based on the second adjacent cell list without having to acquire and decode system information (SIB1) from the adjacent cell. Thus, efficient cell reselection becomes possible.

[0027] (Base station configuration) Next, with reference to Figure 3, the configuration of the base station 200 according to this embodiment will be described. The base station 200 includes a communication unit 210, a network interface 220, and a control unit 230.

[0028] The communication unit 210, for example, receives a radio signal from the UE 100 and transmits a radio signal to the UE 100. The communication unit 210 may include one or more receivers for receiving radio signals and one or more transmitters for transmitting radio signals.

[0029] The network interface 220 transmits and receives signals to and from the network. For example, the network interface 220 receives signals from an adjacent base station connected via the Xn interface, which is an inter-base station interface, and transmits signals to the adjacent base station. The network interface 220 also receives signals from a core network device 300 connected via the NG interface, and transmits signals to the core network device 300.

[0030] The control unit 230 performs various controls on the base station 200. For example, the control unit 230 controls communication with the UE 100 via the communication unit 210. The control unit 230 also controls communication with nodes (e.g., adjacent base stations, core network equipment 300) via the network interface 220. The operation of the base station 200, as described later, may be controlled by the control unit 230.

[0031] The control unit 230 may include at least one processor capable of executing a program and a memory for storing the program. The processor may execute the program to operate the control unit 230. The control unit 230 may also include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and RF circuit. This digital processing includes processing of the RAN protocol stack. The memory stores the program executed by the processor, parameters related to the program, and data related to the program. All or part of the memory may be contained within the processor.

[0032] In a base station 200 configured in this way, the communication unit 210 broadcasts system information in the cell that UE 100s located within the base station's cell use to perform cell reselection by selecting a different adjacent cell as a candidate. Specifically, the communication unit 110 broadcasts system information that includes a second adjacent cell list, which is different from the first adjacent cell list for general UE 100A, as an adjacent cell list indicating adjacent cells to be excluded from the candidates for cell reselection or adjacent cells to be considered as candidates for cell reselection. The second adjacent cell list is an adjacent cell list for a specific UE 100B.

[0033] (Example of protocol stack configuration) Next, with reference to Figure 4, an example of the protocol stack configuration according to this embodiment will be described.

[0034] The protocol for the radio section between UE100 and base station 200 has a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an RRC layer.

[0035] The PHY layer performs coding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of base station 200 via a physical channel.

[0036] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), and random access procedures. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of base station 200 via the transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the transport format for the uplink and downlink (transport block size, modulation coding scheme (MCS)) and the resources to be allocated to UE100.

[0037] The RLC layer transmits data to the receiving RLC layer by utilizing the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of base station 200 via a logical channel.

[0038] The PDCP layer performs header compression / decompression, and encryption / decryption.

[0039] An SDAP (Service Data Adaptation Protocol) layer may be provided as a layer above the PDCP layer. The SDAP layer maps IP flows, which are the units in which the core network performs QoS control, to wireless bearers, which are the units in which the AS (Access Stratum) performs QoS control.

[0040] The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of base station 200. If there is an RRC connection between the RRC of UE100 and the RRC of base station 200, UE100 is in the RRC connected state. If there is no RRC connection between the RRC of UE100 and the RRC of base station 200, UE100 is in the RRC idle state. If the RRC connection between the RRC of UE100 and the RRC of base station 200 is suspended, UE100 is in the RRC inactive state.

[0041] The NAS layer, located above the RRC layer, handles session management and mobility management for the UE100. NAS signaling is transmitted between the NAS layer of the UE100 and the NAS layer of the mobility management device 221.

[0042] In addition to the wireless interface protocol, the UE100 also has an application layer and other components.

[0043] (Overview of cell selection and re-selection by UE) Next, we will explain the overview of cell selection and cell re-selection by UE100. UE100 can perform cell selection or cell re-selection as selection actions for selecting camp-on cells. UE100 can perform selection actions in any of the following cases, for example:

[0044] • If a new PLMN (Public Land Mobile Network) or a new SNPN (Stand-alone Non-Public Network) is selected • When a USIM (Universal Subscriber Identity Module) is inserted into the UE100 or when an SNPN subscription is added. • If a suitable cell cannot be found When transitioning from RRC Connected state to RRC Idle state or RRC Inactive state

[0045] (A) Cell selection During cell selection, the UE100 searches the frequency band to identify the strongest cell for each frequency (for example, the cell with the highest detection level for CD-SSB (cell-defining SS / PBCH Block), the cell with the highest received power (RSRP) for CD-SSB, or the cell with the highest received quality (RSRQ) for CD-SSB). Next, the UE100 identifies a suitable cell from among the strongest cells. If the UE100 cannot identify a suitable cell (i.e., no suitable cell is found), it identifies an acceptable cell. If the UE100 can identify a suitable cell (i.e., a suitable cell is found), it selects the suitable cell as the camp-on cell. If the UE100 can only identify acceptable cells (i.e., only acceptable cells are found), it selects an acceptable cell as the camp-on cell.

[0046] A suitable cell is one whose measured cell quality meets the cell selection criteria. The PLMN of a suitable cell is a selected PLMN, a registered PLMN, or a PLMN equal to those PLMNs. A suitable cell is not a prohibited or reserved cell, and is not part of a tracking area included in the "Prohibited Tracking Areas for Roaming" list. An acceptable cell is one whose measured cell quality meets the cell selection criteria and is not a prohibited cell.

[0047] For example, the cell selection criteria are, for example, Srxlev > 0 and Squal > 0. Srxlev represents the cell selection received power. Srxlev is calculated by Srxlev = Q -(Q rxlevmin +Q rxlevminoffset )-P compensation -Qoffset temp where Q rxlevmeas is the received power (RSRP) of the measured cell. Q rxlevmin is the minimum required received power. Q rxlevminoffset is a predetermined offset that is constantly applied. P compensation is a parameter related to the uplink capability. Qoffset temp is an offset that is temporarily applied. Squal represents the cell selection quality level. Squal is calculated by Squal = Q qualmeas -(Q qualmin +Q qualminoffset )-Qoffset temp where Q qualmeas is the quality level (RSRQ) of the measured cell. Q qualmin is the minimum required quality level. Q qualminoffset is a predetermined offset that is constantly applied. Qoffset temp is an offset that is temporarily applied.

[0048] (B) Cell reselection In cell reselection, the UE 100 in the RRC idle state or the RRC inactive state measures the communication quality of the serving cell and adjacent cells. The UE 100 selects the camping-on cell to be used as the serving cell based on, for example, the following criteria. The UE 100 determines the priority of the selected cell according to the frequency priority. The UE 100 may select the camping-on cell based on the following criteria when more than 1 second has elapsed since camping on the current serving cell.

[0049] (B1) The priority of the frequency of the adjacent cell is higher than the priority of the frequency of the current serving cell: The UE 100 shall, within a predetermined period (e.g., TreselectionRAT ) over Squal>Thresh X,HighQ Cells that satisfy the relationship, or Srxlev > Thresh over a specified period of time X,HighP Select the cells that satisfy the relationship. Thresh X,HighP and Thresh X,HighQ Each of these is a predetermined threshold.

[0050] (B2) The frequency priority of the adjacent cell is the same as the frequency priority of the current serving cell: UE100 calculates the current serving cell's ranking Rs and the neighboring cells' ranking Rn. UE100 selects cells with a ranking Rn higher than Rs over a predetermined period as camp-on cells.

[0051] For example, Rs = Q meas,s +Q hyst -Qoffset temp It is calculated by Rn = Q. meas,n -Qoffset-Qoffset temp It is calculated by Q. meas,s This is the current receiving power (RSRP) of the serving cell. Q meas,n This is the received power (RSRP) of the adjacent cell. Q hyst This is a hysteresis value that makes it easier for the current serving cell to be reselected. Qoffset temp This is a temporary offset.

[0052] (B3) The frequency priority of the adjacent cell is lower than the frequency priority of the current serving cell: For example, UE100 is Squal over a predetermined period of time <Thresh Serving,LowQ Alternatively, Srxlev <Thresh Serving,LowP Assuming that the serving cell satisfies the relationship, Squal > Thresh over a predetermined period of time X,LowQ Cells that satisfy the relationship, or Srxlev > Thresh over a specified period of time X,LowP Select the cells that satisfy the relationship. Thresh X,LowPand Thresh X,LowQ Each of these is a predetermined threshold.

[0053] The various parameters used in cell selection are included in the System Information Block (SIB) broadcast from the base station 200. These parameters include, for example, frequency priority (e.g., cellReselectionPriority, cellReselectionSubPriority) and a predetermined period (Treselection). RAT ), various offsets (Q qualminoffset Q rxlevminoffset Q offsettemp Q hyst Q offset ), various thresholds (Thresh X,HighQ Thresh X,HighP Thresh Serving,LowQ Thresh Serving,LowP Thresh X,LowP Thresh X,LowQ ) is included. cellReselectionPriority indicates frequency priority in 8 levels, and cellReselectionSubPriority indicates frequency subpriority in 4 levels. This allows UE100 to set up to 32 levels of frequency priority. The frequency priority may be notified to UE100 via an RRC release message.

[0054] (System operation) Next, the operation of the mobile communication system 1 according to this embodiment will be described.

[0055] (1) Example of an operating environment Referring to Figure 5, an example of the operating environment of the mobile communication system 1 according to this embodiment will be described.

[0056] In Figure 5, cells C1 to C7 are shown as examples of cells in the mobile communication system 1. Cell C1 is a cell belonging to frequency F1, has a physical cell identifier (PCI) of PCI#a, and supports specific UE100B. Cell C2 is a cell belonging to frequency F1, has a PCI#b, and does not support specific UE100B. Cell C3 is a cell belonging to frequency F2, has a PCI#c, and supports specific UE100B. Cell C4 is a cell belonging to frequency F3, has a PCI#d, and does not support specific UE100B. Cell C5 is a cell belonging to frequency F4, has a PCI#e, and supports specific UE100B. Cell C6 is a cell belonging to frequency F1, has a PCI#f, and supports specific UE100B. Cell C7 is a cell belonging to frequency F2, has a PCI#g, and supports specific UE100B. Furthermore, the UE100 can detect a cell and recognize its PCI by receiving synchronization signals and reference signals transmitted by each cell, such as SS / PBCH Block (SSB).

[0057] Thus, the mobile communication system 1 may contain a mixture of cells with various frequencies, and may also contain cells that support a specific UE100B and cells that do not. Each cell may be managed by a different base station 200.

[0058] Figure 5 shows an example where UE100, in an RRC idle or RRC inactive state, has selected cell C1 as the camp-on cell. With cell C1 as the reference, cells C2 through C7 are adjacent cells. Furthermore, with cell C1 as the reference, cells C2 and C6 are intra-frequency adjacent cells, while the other cells are inter-frequency adjacent cells.

[0059] Here, we assume that UE100 is a specific UE100B. UE100, which is in an RRC idle or RRC inactive state, periodically monitors paging from base station 200, which manages cell C1. Here, UE100 changes its camp-on cell from cell C1 to an adjacent cell, for example, by performing cell reselection when its own UE moves. However, since cells C2 and C4 among the adjacent cells do not support specific UE100B, specific UE100B cannot camp on to cells C2 and C4.

[0060] In this embodiment, the base station 200 managing cell C1 broadcasts system information in cell C1 that UEs 100 located in cell C1 use to perform cell reselection by selecting a different adjacent cell as a candidate. Specifically, the base station 200 managing cell C1 broadcasts system information that includes a second adjacent cell list, which is different from the first adjacent cell list for general UEs 100A, as an adjacent cell list indicating adjacent cells that should be excluded from the candidates for cell reselection or adjacent cells that should be considered as candidates for cell reselection. The second adjacent cell list is an adjacent cell list for a specific UE 100B. As a result, a specific UE 100B located in cell C1 can determine whether or not an adjacent cell can be considered as a candidate for cell reselection based on the second adjacent cell list, without having to acquire and decode system information (SIB1) from the adjacent cell. Thus, efficient cell reselection becomes possible.

[0061] (2) Example of an operation flow Referring to Figure 6, an example of the operation flow of the mobile communication system 1 according to this embodiment will be described. Here, it is assumed that a general UE100A and a specific UE100B are located in cell C1.

[0062] In step S1, the general UE100A is in an RRC idle state or RRC inactive state in cell C1.

[0063] In step S2, specific UE100B is in an RRC idle or RRC inactive state in cell C1.

[0064] In steps S3 and S4, the base station 200 (communication unit 210) broadcasts system information in cell C1 that the UE100s (general UE100A and specific UE100B) located in cell C1 will use to reselect a cell from an adjacent cell different from cell C1. The general UE100A (communication unit 110) and the specific UE100B (communication unit 110) each receive the system information.

[0065] The base station 200 (communication unit 210) broadcasts system information by transmitting it using a broadcast channel. The system information is information that can be received (acquired) even by UE100 in an RRC idle state or RRC inactive state. The base station 200 (communication unit 210) may broadcast such system information periodically.

[0066] Specifically, in step S3, the base station 200 (communication unit 210) broadcasts a first system information block for cell reselection to an intra-frequency adjacent cell, which is an adjacent cell belonging to the same frequency as cell C1. For example, the first system information block is a system information block type 3 (SIB3). SIB3 contains adjacent cell-related information for intra-frequency cell reselection.

[0067] Furthermore, in step S4, the base station 200 (communication unit 210) broadcasts a second system information block for cell reselection to an inter-frequency adjacent cell, which is an adjacent cell belonging to a different frequency than the frequency of cell C1. For example, the second system information block is a system information block type 4 (SIB4). SIB4 includes information regarding inter-frequency cell reselection (i.e., information regarding the adjacent NR frequency and inter-frequency adjacent cell related to cell reselection). Note that steps S3 and S4 may be performed in reverse order, or steps S3 and S4 may be performed simultaneously.

[0068] In step S5, the general UE100A (control unit 120) controls cell reselection based on the first adjacent cell list included in the system information received from gNB200 (cell C1). Specifically, the general UE100A (control unit 120) performs intra-frequency cell reselection control based on the first adjacent cell list included in the first system information block, and inter-frequency cell reselection control based on the first adjacent cell list included in the second system information block.

[0069] In step S6, the specific UE100B (control unit 120) controls cell reselection based on the second adjacent cell list included in the system information received from gNB200 (cell C1). Specifically, the specific UE100B (control unit 120) performs intra-frequency cell reselection control based on the second adjacent cell list included in the first system information block, and inter-frequency cell reselection control based on the first adjacent cell list included in the second system information block.

[0070] Thus, when the UE 100 is a specific UE 100B, the control unit 120 controls cell reselection based on the second adjacent cell list included in the system information. This makes it possible to use a second adjacent cell list optimized for the specific UE 100B, and to appropriately determine, based on the second adjacent cell list, which adjacent cells should be excluded from the candidates for cell reselection or which adjacent cells should be considered as candidates for cell reselection.

[0071] Specifically, the specific UE100B (control unit 120) controls cell re-selection based on the second adjacent cell list contained in the first system information block and the second system information block, respectively. This allows the specific UE100B (control unit 120) to appropriately determine adjacent cells that should be excluded from candidates for intra-cell re-selection or adjacent cells that should be considered as candidates for intra-frequency cell re-selection, based on the second adjacent cell list contained in the first system information block. Furthermore, the specific UE100B (control unit 120) can appropriately determine adjacent cells that should be excluded from candidates for inter-frequency cell re-selection or adjacent cells that should be considered as candidates for inter-frequency cell re-selection, based on the second adjacent cell list contained in the second system information block.

[0072] (3) An example of the first system information block Referring to Figure 7, an example of the first system information block according to this embodiment will be described.

[0073] As described above, the first system information block is a system information block for intra-frequency cell reselection for intra-frequency adjacent cells, for example, SIB3.

[0074] SIB3 includes a first adjacent cell list indicating adjacent cells that a general UE100A should exclude from candidates for intra-frequency cell reselection or adjacent cells that should be considered as candidates for intra-frequency cell reselection. The first adjacent cell list includes at least one of "IntraFreqBlackCellList" shown in A1 of Figure 7 and "IntraFreqWhiteCellList-r16" shown in A2 of Figure 7. "IntraFreqBlackCellList" is an information element that indicates adjacent cells that a general UE100A should exclude from candidates for intra-frequency cell reselection in one or more PCI ranges (SEQUENCE (SIZE (1..maxCellBlack)) OF PCI-Range) (see A4 of Figure 7). "IntraFreqWhiteCellList-r16" is an information element that indicates, in one or more PCI ranges (SEQUENCE (SIZE (1..maxCellWhite)) OF PCI-Range), adjacent cells that a general UE100A should consider as candidates for intra-frequency cell reselection (see A4 in Figure 7).

[0075] Furthermore, SIB3 includes a second adjacent cell list indicating adjacent cells that a specific UE100B should exclude from candidates for intra-frequency cell reselection, or adjacent cells that a specific UE100B should consider as candidates for intra-frequency cell reselection.

[0076] The second adjacent cell list included in SIB3 may be at least one of the following, as shown in A3 of Figure 7: "IntraFreqExcludedCellListRedCap-r17", which is a first exclusion cell list indicating intra-frequency adjacent cells that a specific UE100B should exclude from candidates; "IntraFreqExcludedCellListSingleRx-r17", which is a second exclusion cell list indicating intra-frequency adjacent cells that a UE100 having only one receiver 111 (specific UE100B) should exclude from candidates; and "IntraFreqExcludedCellListDualRx-r17", which is a third exclusion cell list indicating intra-frequency adjacent cells that a UE100 having only two receivers 111 (specific UE100B) should exclude from candidates. Each of "IntraFreqExcludedCellListRedCap-r17", "IntraFreqExcludedCellListSingleRx-r17", and "IntraFreqExcludedCellListDualRx-r17" is an information element that indicates one or more PCI ranges (SEQUENCE (SIZE (1..maxCellBlack)) OF PCI-Range) of adjacent cells that should be excluded from candidates for intra-frequency cell reselection (see A5 in Figure 7). This allows the specific UE100B (control unit 120) to appropriately determine which adjacent cells should be excluded from candidates in intra-frequency cell reselection based on at least one of "IntraFreqExcludedCellListRedCap-r17", "IntraFreqExcludedCellListSingleRx-r17", and "IntraFreqExcludedCellListDualRx-r17".

[0077] The second adjacent cell list included in SIB3 may be at least one of the following, as shown in A3 of Figure 7: "IntraFreqAllowedCellListRedCap-r17", which is a first allowed cell list indicating intra-frequency adjacent cells that a specific UE100B should consider as candidates for intra-frequency cell reselection; "IntraFreqAllowedCellListSingleRx-r17", which is a second allowed cell list indicating intra-frequency adjacent cells that a UE100 having only one receiver 111 (specific UE100B) should consider as candidates for intra-frequency cell reselection; and "IntraFreqWAllowedCellListDualRx-r17", which is a third allowed cell list indicating intra-frequency adjacent cells that a UE100 having only two receivers 111 (specific UE100B) should consider as candidates for intra-frequency cell reselection. Each of "IntraFreqAllowedCellListRedCap-r17", "IntraFreqAllowedCellListSingleRx-r17", and "IntraFreqWAllowedCellListDualRx-r17" is an information element that indicates one or more PCI ranges (SEQUENCE (SIZE (1..maxCellWhite)) OF PCI-Range) of adjacent cells that should be candidates for intra-frequency cell reselection (see A5 in Figure 7). As a result, the specific UE100B (control unit 120) can appropriately determine adjacent cells that should be candidates for intra-frequency cell reselection based on at least one of "IntraFreqAllowedCellListRedCap-r17", "IntraFreqAllowedCellListSingleRx-r17", and "IntraFreqWAllowedCellListDualRx-r17".

[0078] (4) An example of the second system information block Referring to Figure 8, an example of a second system information block according to this embodiment will be described.

[0079] As described above, the second system information block is a system information block for inter-frequency cell reselection for inter-frequency adjacent cells, for example, SIB4.

[0080] SIB4 includes a first adjacent cell list indicating adjacent cells that a general UE100A should exclude from candidates for inter-frequency cell reselection or adjacent cells that should be considered as candidates for inter-frequency cell reselection. The first adjacent cell list includes at least one of "InterFreqBlackCellList" shown in B1 of Figure 8 and "InterFreqWhiteCellList-r16" shown in B2 of Figure 8. "InterFreqBlackCellList" is an information element that indicates adjacent cells that a general UE100A should exclude from candidates for inter-frequency cell reselection in one or more PCI ranges (SEQUENCE (SIZE (1..maxCellBlack)) OF PCI-Range) (see B4 of Figure 8). "InterFreqWhiteCellList-r16" is an information element that indicates, in one or more PCI ranges (SEQUENCE (SIZE (1..maxCellWhite)) OF PCI-Range), adjacent cells that a general UE100A should consider as candidates for inter-frequency cell reselection (see B4 in Figure 8).

[0081] Furthermore, SIB4 includes a second adjacent cell list indicating adjacent cells that a specific UE100B should exclude from candidates for inter-frequency cell reselection, or adjacent cells that a specific UE100B should consider as candidates for inter-frequency cell reselection.

[0082] The second adjacent cell list included in SIB4 may be at least one of the following, as shown in B3 of Figure 8: "InterFreqExcludedCellListRedCap-r17", which is a first exclusion cell list indicating inter-frequency adjacent cells that a specific UE100B should exclude from candidates; "InterFreqExcludedCellListSingleRx-r17", which is a second exclusion cell list indicating inter-frequency adjacent cells that a UE100 having only one receiver 111 (specific UE100B) should exclude from candidates; and "InterFreqExcludedCellListDualRx-r17", which is a third exclusion cell list indicating inter-frequency adjacent cells that a UE100 having only two receivers 111 (specific UE100B) should exclude from candidates. Each of "InterFreqExcludedCellListRedCap-r17", "InterFreqExcludedCellListSingleRx-r17", and "InterFreqExcludedCellListDualRx-r17" is an information element that indicates one or more PCI ranges (SEQUENCE (SIZE (1..maxCellBlack)) OF PCI-Range) of adjacent cells that should be excluded from candidates for inter-frequency cell reselection (see B5 in Figure 8). As a result, the specific UE100B (control unit 120) can appropriately determine which adjacent cells should be excluded from candidates in inter-frequency cell reselection based on at least one of "InterFreqExcludedCellListRedCap-r17", "InterFreqExcludedCellListSingleRx-r17", and "InterFreqExcludedCellListDualRx-r17".

[0083] The second adjacent cell list included in SIB4 may be at least one of the following, as shown in B3 of Figure 8: "InterFreqAllowedCellListRedCap-r17", which is a first permitted cell list indicating inter-frequency adjacent cells that a specific UE100B should consider as candidates for inter-frequency cell reselection; "InterFreqAllowedCellListSingleRx-r17", which is a second permitted cell list indicating inter-frequency adjacent cells that a UE100 having only one receiver 111 (specific UE100B) should consider as candidates for inter-frequency cell reselection; and "InterFreqWAllowedCellListDualRx-r17", which is a third permitted cell list indicating inter-frequency adjacent cells that a UE100 having only two receivers 111 (specific UE100B) should consider as candidates for inter-frequency cell reselection. Each of "InterFreqAllowedCellListRedCap-r17", "InterFreqAllowedCellListSingleRx-r17", and "InterFreqWAllowedCellListDualRx-r17" is an information element that indicates one or more PCI ranges (SEQUENCE (SIZE (1..maxCellWhite)) OF PCI-Range) of adjacent cells that should be candidates for inter-frequency cell reselection (see B5 in Figure 8). As a result, the specific UE100B (control unit 120) can appropriately determine adjacent cells that should be candidates for inter-frequency cell reselection based on at least one of "InterFreqAllowedCellListRedCap-r17", "InterFreqAllowedCellListSingleRx-r17", and "InterFreqWAllowedCellListDualRx-r17".

[0084] (Other embodiments) In the embodiments described above, an example was described in which each of the first system information block and the second system information block includes a second adjacent cell list. However, the second adjacent cell list may be included in only one of the first system information block or the second system information block. Furthermore, although an example was described in which the second adjacent cell list controls the re-selection of a specific UE100B, the second adjacent cell list may further control the cell selection of a specific UE100B.

[0085] In the embodiments described above, the base station 200 may include a plurality of units. The plurality of units may include a first unit that hosts the higher layer included in the protocol stack, and a second unit that hosts the lower layer included in the protocol stack. The higher layer may include the RRC layer, SDAP layer, and PDCP layer, and the lower layer may include the RLC layer, MAC layer, and PHY layer. The first unit may be a CU (central unit), and the second unit may be a DU (Distributed Unit). The plurality of units may include a third unit that performs processing below the PHY layer. The second unit may perform processing above the PHY layer. The third unit may be a RU (Radio Unit). The base station 200 may be one of the plurality of units and may be connected to other units of the plurality of units. The base station 200 may also be an IAB (Integrated Access and Backhaul) donor or IAB node.

[0086] In the embodiments described above, a mobile communication system based on NR was used as an example for the mobile communication system 1. However, the mobile communication system 1 is not limited to this example. The mobile communication system 1 may be a system compliant with LTE or another generation system of the 3GPP standard (e.g., 6th generation). The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination directed to UE100 in LTE. The mobile communication system 1 may be a system compliant with a TS of a standard other than the 3GPP standard.

[0087] The steps in the operation of the above-described embodiment do not necessarily have to be executed chronologically in the order shown in the flowchart or sequence diagram. For example, the steps in the operation may be executed in a different order than that shown in the flowchart or sequence diagram, or they may be executed in parallel. Also, some steps in the operation may be deleted, or further steps may be added to the process. Furthermore, each of the above-described operation flows can be implemented not only separately and independently, but also by combining two or more operation flows. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow.

[0088] A program may be provided that causes a computer to execute each process performed by the UE100 or base station 200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or DVD-ROM. Alternatively, the circuits that execute each process performed by the UE100 or base station 200 may be integrated, and at least a part of the UE100 or base station 200 may be configured as a semiconductor integrated circuit (chipset, SoC).

[0089] In the embodiments described above, “transmit” may mean processing at least one layer in the protocol stack used for transmission, or it may mean physically transmitting a signal wirelessly or via a wire. Alternatively, “transmit” may mean a combination of processing at least one layer and physically transmitting a signal wirelessly or via a wire. Similarly, “receive” may mean processing at least one layer in the protocol stack used for reception, or it may mean physically receiving a signal wirelessly or via a wire. Alternatively, “receive” may mean a combination of processing at least one layer and physically receiving a signal wirelessly or via a wire.

[0090] Although the embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to those described above, and various design changes can be made without departing from the gist of the invention. [Explanation of symbols]

[0091] 1: Mobile communication systems 10: Network 100 :UE 100A: General UE 100B:Specific UE 110: Communications Department 111: Receiver 112: Transmitter 120: Control Unit 200:Base station 210: Communications Department 220: Network Interface 221: Mobility management device 230: Control Unit 300: Core network device C1: Cell C2: Cell C3: Cell C4: Cell C5: Cell C6: Cell C7: Cell

Claims

1. A communication device (100), The system receives a system information block 1 (SIB1) from the base station (200) which contains information indicating whether or not to allow access to the cell of the Reduced Capability user device. A communication unit (110) receives a system information block 3 (SIB3) containing information regarding intra-frequency cell reselection, and a system information block 4 (SIB4) containing information regarding inter-frequency cell reselection from the base station (200), If the communication device is the Reduced Capability user device, then, based on the information included in the SIB1 indicating whether or not to allow access to the cells of the Reduced Capability user device, cells that are indicated as not being allowed to be selected in cell re-selection. When performing the intra-frequency cell reselection, the intra-frequency cell reselection is controlled based on the intra-frequency cell reselection information included in the SIB3. The system includes a control unit (120) that controls the inter-frequency cell reselection when performing the inter-frequency cell reselection, based on information included in the SIB4 indicating the priority of carrier frequencies used for the inter-frequency cell reselection and information indicating permission for access to the Reduced Capability user device. The control unit (120) In the control of inter-frequency cell reselection, the received power of the cell belonging to the carrier frequency is measured based on the CD-SSB (cell-defining SS / PBCH Block), and an appropriate cell is selected. Communication device (100).

2. The communication unit (110) receives the SIB4 from the base station (200) which includes information indicating the period used for inter-frequency cell reselection and information indicating a threshold. In the inter-frequency cell reselection, the control unit (120) selects an appropriate cell belonging to a carrier frequency with a higher priority than the carrier frequency to which the serving cell belongs, based on the period and the threshold. The communication device (100) according to claim 1.

3. Base station (200), A system information block 1 (SIB1) containing information indicating whether or not to allow access to the cells of the Reduced Capability user device is transmitted to the communication device (100). A communication unit (210) transmits a system information block 3 (SIB3) containing information regarding intra-frequency cell reselection, and a system information block 4 (SIB4) containing information regarding inter-frequency cell reselection, to the communication device (100). If the communication device is the Reduced Capability user device, the communication device (100) is controlled to not select cells that indicate access is not permitted in cell reselection, based on information included in the SIB1 indicating whether or not to allow access to the cells of the Reduced Capability user device. Based on the information regarding intra-frequency cell reselection included in the SIB3, the communication device (100) is controlled to perform the intra-frequency cell reselection. The system includes a control unit (230) that controls the communication device (100) to perform inter-frequency cell reselection based on information included in the SIB4 indicating the priority of carrier frequencies used for inter-frequency cell reselection, and information indicating permission for access to the Reduced Capability user device, The control unit (230) is In the control of inter-frequency cell reselection, the received power of the cell belonging to the carrier frequency is measured based on the CD-SSB (cell-defining SS / PBCH Block), and the communication device (100) is controlled to select an appropriate cell. Base station (200).

4. The communication unit (210) transmits the SIB4, which includes information indicating the period used for inter-frequency cell reselection and information indicating a threshold, to the communication device (100). The control unit (230) controls the communication device (100) to select the appropriate cell belonging to a carrier frequency with a higher priority than the carrier frequency to which the serving cell belongs, based on the period and the threshold, during the inter-frequency cell reselection. The base station (200) according to claim 4.

5. A communication method performed by a communication device (100), The steps include receiving a system information block 1 (SIB1) from a base station (200) which contains information indicating whether or not to allow access to the cell of the Reduced Capability user device, The steps include receiving a system information block 3 (SIB3) containing information regarding intra-frequency cell reselection and a system information block 4 (SIB4) containing information regarding inter-frequency cell reselection from the base station (200), If the communication device is the Reduced Capability user device, the step of not selecting a cell that is indicated as not permitted in cell reselection, based on the information included in the SIB1 that indicates whether or not to allow access to the cells of the Reduced Capability user device, When performing the intra-frequency cell reselection, the steps include controlling the intra-frequency cell reselection based on the intra-frequency cell reselection information included in the SIB3, The process includes a step of controlling the inter-frequency cell reselection when performing the inter-frequency cell reselection, based on information included in the SIB4 indicating the priority of carrier frequencies used for the inter-frequency cell reselection and information indicating permission for access by the Reduced Capability user device. In the step of controlling the inter-frequency cell reselection, the received power of the cell is measured based on the CD-SSB (cell-defining SS / PBCH Block) of the cell belonging to the carrier frequency, and an appropriate cell is selected. Communication method.

6. The process further includes receiving the SIB4 from the base station (200), which includes information indicating the period used for inter-frequency cell reselection and information indicating a threshold. In the step of controlling the inter-frequency cell reselection, based on the period and the threshold, an appropriate cell belonging to a carrier frequency with a higher priority than the carrier frequency to which the serving cell belongs is selected. The communication method according to claim 5.

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