Base station and communication method

Abstract

To provide a base station and a communication control method that can prevent a capability-limited user device from failing handover.SOLUTION: A base station (200 or 201) according to one aspect of the present disclosure includes: a network communication unit (213) that receives information for determination for determining whether communication is possible between a capability-limited user device (100) with limited communication capability and an adjacent base station (200, 202, or 203) from the adjacent base station (200, 202, or 203); and a control unit (214) that acquires the information for determination.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a base station and a communication control method for use in a mobile communication system. [Background technology]

[0002] In recent years, 3GPP, a standardization project for mobile communication systems, has been considering providing limited-capability user equipment (so-called RedCap UE) with more limited communication capabilities than normal user equipment in a 5G system (see, for example, Non-Patent Document 1). For example, such limited-capability user equipment has a limited maximum bandwidth used for communication or a limited number of receiving branches. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP contribution “R2-210918” Summary of the Invention [Problem to be solved by the invention]

[0004] Since base stations need to control communication with limited-capability user equipment differently from communication with normal user equipment, there may be base stations that cannot communicate with limited-capability user equipment.

[0005] Here, when a limited-capability user equipment is in an RRC connected state in which an RRC connection is established between the base station and the limited-capability user equipment, it is assumed that, for example, due to movement of the limited-capability user equipment, a handover occurs from a cell managed by the base station to an adjacent cell managed by an adjacent base station.

[0006] If the neighboring base station does not support communication with limited-capability user equipment, the limited-capability user equipment may fail to hand over to the neighboring cell, resulting in a problem of interruption of communication of the limited-capability user equipment.

[0007] Therefore, an object of the present invention is to provide a base station and a communication control method that can suppress handover failures of limited-capability user equipment. [Means for solving the problem]

[0008] A base station according to one embodiment of the present disclosure includes a network communication unit that receives, from an adjacent base station, determination information for determining whether a limited-capability user device having limited communication capabilities can communicate with the adjacent base station, and a control unit that acquires the determination information.

[0009] A base station according to one embodiment of the present disclosure includes a control unit that generates determination information for an adjacent base station to determine whether or not the base station can communicate with a limited-capability user device having limited communication capabilities, and a network communication unit that transmits the determination information to the adjacent base station.

[0010] A communication control method according to one aspect of the present disclosure is a communication control method executed by a base station, and includes a step of receiving, from an adjacent base station, determination information for determining whether a capability-limited user device having limited communication capabilities can communicate with the adjacent base station, and a step of acquiring the determination information. Effect of the Invention

[0011] According to one aspect of the present invention, it is possible to provide a base station and a communication control method that can suppress handover failures for limited-capability user equipment. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of a schematic configuration of a system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating an example of a configuration of a protocol stack of a system according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a diagram illustrating an example of the configuration of a UE according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a diagram illustrating a configuration example of a BS according to an embodiment of the present disclosure. [Diagram 5] FIG. 2 is a diagram illustrating a first operation example of the mobile communication system according to the embodiment of the present disclosure. [Figure 6] FIG. 13 is a diagram illustrating an example of information included in a message according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a diagram showing an operation example of a BS in an operation example 1 of a mobile communication system according to an embodiment of the present disclosure. [Figure 8] FIG. 2 is a diagram showing an operation example of a BS in an operation example 1 of a mobile communication system according to an embodiment of the present disclosure. [Figure 9] FIG. 11 is a diagram illustrating a second operation example of the mobile communication system according to the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and the drawings, elements that can be similarly described may be denoted by the same or similar reference numerals to avoid redundant description.

[0014] (1) System Configuration (1.1) System Overview With reference to FIG. 1, an example of the configuration of a system 1 according to an embodiment of the present disclosure will be described. The system 1 is, for example, a mobile communication system that complies with the Technical Specification (TS) of 3GPP, which is a standardization project for mobile communication systems. In the following, the system 1 will be described using as an example a 5th Generation System (5GS) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio). Note that the system 1 is not limited to this example. The system 1 may be a system that complies with the TS of either LTE (Long Term Evolution) or another generation system (e.g., 6th generation) of the 3GPP standard. The system 1 may be a system that complies with the TS of a standard other than the 3GPP standard.

[0015] As shown in FIG. 1, the system 1 includes a 5G radio access network (so-called Next Generation Radio Access Network: NG-RAN) 20, a 5G core network (5G Core Network: 5GC) 30, and a user equipment (UE: UE) 100.

[0016] The NG-RAN 20 includes a base station (BS) 200, which is a node of a radio access network. The BS 200 is a radio communication device that performs radio communication with the UE 100. The BS 200 manages one or more cells. The BS 200 performs radio communication with the UE 100 that has established a connection with the cell in a radio resource control (RRC) layer. The base station 200 has a radio resource management (RRM) function, a routing function for user data (hereinafter simply referred to as "data"), a measurement control function for mobility control and scheduling, and the like. The term "cell" is used as a term indicating the smallest unit of a radio communication area. The term "cell" is also used as a term indicating a function or resource for performing radio communication with the UE 100. One cell belongs to one carrier frequency. FIG. 1 shows an example in which the BS 201 manages a cell C1 and the BS 202 manages a cell C2. The UE 100 is located in an overlapping area of ​​the cells C1 and C2.

[0017] The BS 200 communicates with the UE 100 using, for example, a protocol stack of the RAN. The protocol stack includes, for example, a Radio Resource Control (RRC) layer, a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. However, in the case of LTE, the SDAP layer may not exist.

[0018] The BS 200 is, for example, a gNB that provides an NR user plane and a control plane protocol termination toward the UE 100 and is connected to the 5GC 30 via an NG interface. Note that the BS 200 may be, for example, an eNB that provides an E-UTRA user plane and a control plane protocol termination toward the UE 100 in LTE.

[0019] The BS 200 may include a plurality of units. The plurality of units may include a first unit hosting a higher layer included in a protocol stack and a second unit hosting a lower layer included in the protocol stack. The higher layer may include an RRC layer, an SDAP layer, and a PDCP layer, and the lower layer may include an RLC layer, a MAC layer, and a PHY layer. The first unit may be a central unit (CU), and the second unit may be a distributed unit (DU). The plurality of units may include a third unit performing processing below the PHY layer. The second unit may perform processing above the PHY layer. The third unit may be a radio unit (RU). The BS 200 may be one of the plurality of units and may be connected to other units of the plurality of units. The BS 200 may be an integrated access and backhaul (IAB) donor or an IAB node.

[0020] The 5GC30 includes a core network device 300. The core network device 300 is a device corresponding to the control plane, and may be a device that performs various mobility management for the UE 100. The core network device 300 communicates with the UE 100 using NAS (Non-Access Stratum) signaling, and manages information on a tracking area in which the UE 100 is located. The core network device 300 performs paging through the base station 200 to notify the UE 100 of an incoming call. The core network device 300 may be an AMF (Access and Mobility Management Function) of 5G / NR, or an MME (Mobility Management Entity) of 4G / LTE.

[0021] The core network device 300 is a device corresponding to the user plane, and is a device that performs forwarding control of data of the UE 100. The core network device 300 may be a User Plane Function (UPF) of 5G / NR or a Serving Gateway (S-GW) of 4G / LTE.

[0022] The core network device 300 may include, for example, an AMF and / or a UPF. The core network device 300 is connected to the BS 200 via an NG interface.

[0023] When the UE 100 is located within the coverage area of ​​the BS 200, the UE 100 can communicate with the BS 200. The UE 100 can communicate with the BS 200 using the above-mentioned protocol stack.

[0024] The UE 100 may be any device used by a user. The UE 100 is, for example, a mobile wireless communication device such as a mobile phone terminal such as a smartphone, a tablet terminal, a notebook PC, a communication module, or a communication card. The UE 100 may be a vehicle (e.g., a car, a train, etc.) or a device provided in a vehicle. The UE 100 may be a transport body other than a vehicle (e.g., a ship, an airplane, etc.) or a device provided in a transport body other than a vehicle. The UE 100 may be a sensor or a device provided in a sensor. The UE 100 may be called by another name such as a mobile station, a mobile terminal, a mobile device, a mobile unit, a subscriber station, a subscriber terminal, a subscriber device, a subscriber unit, a wireless station, a wireless terminal, a wireless device, a wireless unit, a remote station, a remote terminal, a remote device, or a remote unit.

[0025] The UE 100 is a limited-capability user equipment (so-called RedCap UE) with a communication capability more limited than that of a normal UE (general UE). Therefore, the RedCap UE has a communication capability that is reduced compared to that of a general UE. The RedCap UE may have a mid-range performance and price for IoT. The general UE is an NR UE, and has, for example, an advanced communication capability that is a feature of NR. Specifically, the general UE is, for example, a UE that satisfies enhanced Mobile Broadband (eMBB) and Ultra-Reliable and Low Latency Communications (URLLC).

[0026] The RedCap UE may be a UE with reduced device cost and complexity compared to a general UE that meets the high performance, high speed, large capacity, and ultra-high reliability and low latency of Rel-15 or Rel-16. The RedCap UE may be capable of communication at a communication speed equal to or higher than the communication speed specified in the LPWA (Low Power Wide Area) standard (e.g., LTE Cat.1 / 1bis, LTE Cat.M1 (LTE-M), LTE Cat.NB1 (NB-IoT)).

[0027] A RedCap UE may be capable of communicating at a bandwidth equal to or greater than the bandwidth specified in the LPWA standard. A RedCap UE may have a limited bandwidth for communication compared to a Rel-15 or Rel-16 UE. In FR1 (Frequency Range 1), for example, the maximum bandwidth of a RedCap UE may be 20 MHz. In FR2 (Frequency Range 2), for example, the maximum bandwidth of a RedCap UE may be 100 MHz.

[0028] The RedCap UE may have only one or two receive chains (Rx chains) for receiving radio signals. In addition, in a frequency band in which a normal UE (so-called legacy NR UE) needs to have at least two receive antenna ports (Rx antenna ports), the RedCap UE may be supported for communication using a single receive branch (Rx branch). In the frequency band, the RedCap UE may be supported for communication using two receive branches.

[0029] In addition, in a frequency band in which a normal UE is required to have at least four receive antenna ports, a RedCap UE may be supported for communication using a single receive branch, and in the frequency band, a RedCap UE may be supported for communication using two receive branches.

[0030] If the RedCap UE has a single receive branch, the maximum number of DL MIMO layers may be 1. If the RedCap UE has two receive branches, the maximum number of DL MIMO layers may be two.

[0031] The RedCap UE may be, for example, an industrial wireless sensor, a video surveillance device, or a wearable device. The RedCap UE may also be referred to as a Reduced capability NR device.

[0032] (1.2) Protocol stack configuration example A configuration example of a protocol stack of the mobile communication system 1 will be described with reference to Fig. 2. As shown in Fig. 2, the protocol of the wireless section between the UE 100 and the base station 200 has a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer.

[0033] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the base station 200 via a physical channel.

[0034] The MAC layer performs data priority control, retransmission processing using hybrid ARQ (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the base station 200 via a transport channel. The MAC layer of the base station 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to the UE 100.

[0035] The RLC layer transmits data to the RLC layer on the receiving side by using the functions of the MAC layer and the PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the base station 200 via logical channels.

[0036] The PDCP layer performs header compression / decompression and encryption / decryption.

[0037] A Service Data Adaptation Protocol (SDAP) layer may be provided above the PDCP layer. The Service Data Adaptation Protocol (SDAP) layer maps IP flows, which are units for QoS control by the core network, to radio bearers, which are units for QoS control by the access stratum (AS).

[0038] The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of the UE 100 and the RRC layer of the base station 200. When there is an RRC connection between the RRC of the UE 100 and the RRC of the base station 200 (i.e., the RRC connection is established), the UE 100 is in an RRC connected state. When there is no RRC connection between the RRC of the UE 100 and the RRC of the base station 200 (i.e., the RRC connection is not established), the UE 100 is in an RRC idle state. When the RRC connection between the RRC of the UE 100 and the RRC of the base station 200 is suspended, the UE 100 is in an RRC inactive state.

[0039] The NAS layer, which is located above the RRC layer, performs session management and mobility management for the UE 100. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the core network device 300.

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

[0041] (1.3) UE Configuration An example of the configuration of the UE 100 will be described with reference to Fig. 3. As shown in Fig. 3, the UE 100 includes a communication unit 120 and a control unit .

[0042] The communication unit 120 communicates with other communication devices by transmitting and receiving signals. For example, the communication unit 120 receives a wireless signal from the BS 200 and transmits the wireless signal to the BS 200. The communication unit 120 may also receive a wireless signal from another UE and transmit the wireless signal to the other UE.

[0043] The communication unit 120 has a receiving unit 121 and a transmitting unit 122. The receiving unit 121 converts a radio signal received by an antenna into a received signal which is a baseband signal, performs signal processing on the received signal, and outputs the signal to the control unit 130. The transmitting unit 122 performs signal processing on a transmission signal which is a baseband signal output by the control unit 130, converts the transmission signal into a radio signal, and transmits the radio signal from the antenna.

[0044] The receiving unit 121 includes one or more receiving chains (i.e., Rx chains). The receiving chain includes a receiving antenna port (i.e., Rx antenna port) and a receiving circuit. The receiving chain may constitute a receiver and may be referred to as a receiver. The receiving chain may constitute a part of the receiver. The receiving chain may also include one or more receiving branches (Rx branches). The receiving branch may include at least a receiving antenna port. The receiving antenna port is a logical receiving antenna consisting of one or more physical antennas.

[0045] The transmitter 122 includes one or more transmission chains (i.e., Tx chains). The transmission chain includes a transmission antenna port (i.e., Tx antenna port) and a transmission circuit. The transmission chain may constitute a transmitter and may be referred to as a transmitter. The transmission chain may constitute a part of the transmitter. The transmission chain may also include one or more transmission branches (Tx branches). The transmission branch may include at least a transmission antenna port. The transmission antenna port is a logical transmission antenna consisting of one or more physical antennas.

[0046] The receiver and the transmitter may be configured as one transceiver, and the antenna may be used for both reception and transmission.

[0047] The control unit 130 performs various controls in the UE 100. For example, the control unit 130 controls communication with the BS 200 or other UEs 100 via the communication unit 120. The operation of the UE 100 described below may be an operation under the control of the control unit 130.

[0048] The control unit 130 may include one or more processors capable of executing a program and a memory that stores the program. The one or more processors may execute the program to perform the operations of the control unit 130. The program may be a program for causing the processor to perform the operations of the control unit 130.

[0049] The processor performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a protocol stack of the RAN. The processor may be a single processor. The processor may include multiple processors. The multiple processors may include a baseband processor for digital processing and one or more processors for other processing. The memory stores programs executed by the processor, parameters related to the programs, and data related to the programs. The memory may include at least one of a Read Only Memory (ROM), an Erasable Programmable Read Only Memory (EPROM), an Electrically Erasable Programmable Read Only Memory (EEPROM), a Random Access Memory (RAM), and a flash memory. All or a part of the memory may be included in the processor.

[0050] In the following, the operation of the functional units (specifically, communication unit 120 and control unit 130) included in UE 100 may be described as the operation of UE 100.

[0051] (1.4) BS Configuration An example of the configuration of the BS 200 will be described with reference to Fig. 4. As shown in Fig. 4, the BS 200 has an antenna 211, a communication unit 212, a network communication unit 213, and a control unit 214.

[0052] The communication unit 212 communicates with the UE 100 via the antenna 211 under the control of the control unit 214. The communication unit 212 has a receiving unit 212a and a transmitting unit 212b. The receiving unit 212a converts a radio signal received by the antenna 211 into a received signal which is a baseband signal, performs signal processing on the received signal, and outputs the signal to the control unit 214. The transmitting unit 212b performs signal processing on a transmission signal which is a baseband signal output by the control unit 214, converts the transmission signal into a radio signal, and transmits the radio signal from the antenna 211.

[0053] Network communication unit 213 is connected to core network device 300. Network communication unit 213 performs network communication with core network device 300 under the control of control unit 214.

[0054] The control unit 214 controls the communication unit 212 and performs various controls in the base station 200. The control unit 214 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processing by the processor. The memory may include at least one of ROM, EPROM, EEPROM, RAM, and flash memory. The processor may include a digital signal processor (DSP) that performs digital processing of digital signals, and a central processing unit (CPU) that executes the programs. Note that a part of the memory may be provided in the communication unit 212. Also, the DSP may be provided in the communication unit 212.

[0055] In the BS 200 configured in this manner, the network communication unit 213 receives, from the adjacent base station, information for determination as to whether the RedCap UE and the adjacent base station are capable of communicating with each other. The control unit 214 acquires the information for determination. This allows the control unit 214 to determine whether the RedCap UE and the adjacent base station are capable of communicating with each other based on the information for determination. This allows the BS 200 to appropriately control the handover destination of the RedCap UE.

[0056] Furthermore, the network communication unit 213 may receive an inter-base station message including determination information for each cell managed by the neighboring base station from the neighboring base station. The control unit 214 can determine whether communication with the RedCap UE is possible for each cell. As a result, the BS 200 can appropriately determine a candidate cell for the handover destination, and therefore can appropriately control the handover destination of the RedCap UE.

[0057] The inter-base station messages are messages used to establish an inter-base station interface between BS 200 and a neighboring base station, or messages related to updating base station settings.

[0058] When the inter-base station message is a message used to establish an inter-base station interface, the control unit 214 can determine whether the RedCap UE and the adjacent base station can communicate when the inter-base station interface is established. Also, when the inter-base station message is a message related to updating the base station setting, the control unit 214 can determine whether the RedCap UE and the adjacent base station can communicate when the base station setting is updated.

[0059] Furthermore, the network communication unit 213 may receive an inter-base station message from the adjacent base station as a response to a message from the BS 200 to the adjacent base station. This allows the control unit 214 to acquire the determination information using the message from the BS 200 as a trigger.

[0060] Furthermore, the control unit 214 may include, in a message from the BS 200 to a neighboring base station, determination information for determining whether the RedCap UE and the BS 200 can communicate with each other. This enables the BS 200 to inform the neighboring base station of whether the RedCap UE and the BS 200 can communicate with each other.

[0061] The information for determination may include at least one of information indicating whether the neighbor base station or the cell managed by the neighbor base station can accept RedCap UE, information indicating whether the neighbor base station or the cell can accept user equipment having a single reception branch of RedCap UE, and information indicating whether the neighbor base station or the cell can accept UE100 having two reception branches of RedCap UE. This allows the control unit 214 to grasp whether the neighbor base station or the cell managed by the neighbor base station can accept RedCap UE. Also, the control unit 214 can grasp whether the neighbor base station or the cell can accept user equipment having a single reception branch of RedCap UE. Also, the control unit 214 can grasp whether the neighbor base station or the cell can accept UE100 having two reception branches of RedCap UE.

[0062] The control unit 214 determines cells to be candidates for the handover destination of the RedCap UE based on the determination information, which enables the BS 200 to appropriately control the handover destination of the RedCap UE.

[0063] The control unit 214 determines whether or not to designate a cell managed by a neighbor base station as a measurement target for measuring wireless quality by the RedCap UE based on the determination information. This allows the BS 200 to appropriately control the measurement target of the RedCap UE.

[0064] In addition, in the BS 200, the control unit 214 generates information for determination by the neighboring base station to determine whether the RedCap UE and the BS 200 can communicate with each other. The network communication unit 213 transmits the information for determination to the neighboring base station. This enables the BS 200 to inform the neighboring base station of whether the RedCap UE and the BS 200 can communicate with each other. The neighboring base station can appropriately control the handover destination of the RedCap UE based on the information for determination.

[0065] In the following description, the operations of the functional units (specifically, communication unit 212, network communication unit 213, and control unit 214) included in BS 200 may be described as the operations of BS 200.

[0066] (2) System operation (2.1) Example 1 With reference to FIG. 5, a first operation example of the UE 100 and the BS 200 (BS 201, BS 202, BS 203) according to the embodiment of the present disclosure will be described.

[0067] In this operation example, BS202 and BS203 are neighbor base stations for BS201. The following description will be given on the assumption that BS201 and BS202 can communicate with RedCap UE, and BS203 cannot communicate with RedCap UE. Therefore, BS201 and BS202 support communication with RedCap UE. BS203 does not support communication with RedCap UE.

[0068] Step S101: Network communication unit 213 of BS 201 transmits an Xn setup request message to BS 202 and BS 203. Network communication units 213 of BS 202 and BS 203 receive the Xn setup request message from BS 201.

[0069] The Xn setup request message is a message used to establish an interface between base stations. For example, the Xn setup request message is sent when starting an Xn setup procedure for establishing an Xn interface. For example, the Xn setup request message is sent to a neighboring base station to transfer application data.

[0070] The control unit 214 of the BS 201 may include, in the Xn setup request message, information for determining whether the RedCap UE and the BS 201 can communicate with each other. Details of the information for determination will be described later. The control units 214 of the BS 202 and the BS 203 may determine that the RedCap UE and the BS 201 can communicate with each other based on the information for determination.

[0071] Step S102: BS202 and network communication unit 213 of BS202 transmit an Xn setup response message to BS201. Network communication unit 213 of BS201 receives an Xn setup response message including the determination information from each of BS202 and BS203.

[0072] The Xn setup response message is a message used to establish an interface between base stations. The Xn setup response message is sent when the Xn setup procedure is successful. The Xn setup response message is a response message to the Xn setup request message.

[0073] The control unit 214 of the BS 202 generates information for determining whether the RedCap UE and the BS 202 can communicate with each other. The control unit 214 of the BS 202 includes the generated information for determination in an Xn setup response message. The information for determination may include at least one of the following information: Information indicating whether the BS 202 or a cell managed by the BS 202 can accept a RedCap UE (hereinafter referred to as redCap-AccessAllowed) Information indicating whether the BS 202 or a cell managed by the BS 202 can accept RedCap UEs having a single receiving branch among RedCap UEs (hereinafter referred to as singleRx-AccessAllowed) Information indicating whether the BS 202 or a cell managed by the BS 202 can accept a RedCap UE having two receiving branches among RedCap UEs (hereinafter referred to as twoRx-AccessAllowed)

[0074] redCap-AccessAllowed may be any of the following information: Information indicating that BS202 (RAN node) supports RedCap UE Information indicating whether BS202 (RAN node) supports RedCap UE Information indicating that RedCap UE can access BS202 (RAN node) · RedCap Information indicating whether UE can access BS202 (RAN node) Information indicating that RedCap UE is allowed to camp on BS202 (RAN node) RedCap Information indicating whether UE is allowed to camp on BS202 (RAN node)

[0075] As shown in FIG. 6, when redCap-AccessAllowed is associated with each cell (eg, physical cell ID) of BS 202, it may be any of the following information: -Information indicating that the cell supports RedCap UE -Information indicating whether the cell supports RedCap UE -Information indicating that RedCap UE can access the cell · RedCap Information indicating whether the UE can access the cell RedCap Information indicating that the UE is allowed to camp on the cell RedCap Information indicating whether the UE is allowed to camp on the cell

[0076] The singleRx-AccessAllowed may be any of the following information: Information indicating that BS202 (RAN node) supports RedCap UE with a single receive branch Information indicating whether the BS 202 (RAN node) supports RedCap UE with a single receiving branch Information indicating that a RedCap UE with a single receiving branch can access BS202 (RAN node) Information indicating whether a RedCap UE with a single receiving branch can access the BS202 (RAN node) Information indicating that a RedCap UE with a single receiving branch is allowed to camp on the BS202 (RAN node) Information indicating whether a RedCap UE with a single receiving branch is allowed to camp on the BS202 (RAN node)

[0077] As shown in FIG. 6, when singleRx-AccessAllowed is associated with each cell (eg, physical cell ID) of BS 202, it may be any of the following information: Information indicating that the cell supports RedCap UE with a single receiving branch Information indicating whether the cell supports RedCap UE with a single receiving branch Information indicating that a RedCap UE with a single receiving branch can access the cell Information indicating whether a RedCap UE with a single receiving branch can access a cell Information indicating that a RedCap UE with a single receiving branch is allowed to camp on the cell Information indicating whether a RedCap UE with a single receiving branch is allowed to camp on a cell

[0078] twoRx-AccessAllowed may be any of the following information: Information indicating that BS202 (RAN node) supports RedCap UE with two receive branches Information indicating whether the BS202 (RAN node) supports RedCap UE with two receive branches Information indicating that a RedCap UE with two receiving branches can access BS202 (RAN node) Information indicating whether a RedCap UE with two receiving branches can access BS202 (RAN node) Information indicating that a RedCap UE with two receive branches is allowed to camp on BS202 (RAN node) Information indicating whether a RedCap UE with two receiving branches is allowed to camp on BS202 (RAN node)

[0079] As shown in FIG. 6, when twoRx-AccessAllowed is associated with each cell (eg, physical cell ID) of BS 202, it may be any of the following information. Information indicating that the cell supports RedCap UE with two receive branches Information indicating whether the cell supports RedCap UE with two receiving branches Information indicating that a RedCap UE with two receiving branches can access the cell Information indicating whether a RedCap UE with two receiving branches can access a cell Information indicating that a RedCap UE with two receiving branches is allowed to camp on the cell Information indicating whether a RedCap UE with two receiving branches is allowed to camp on the cell

[0080] Control unit 214 of BS 203 may generate the determination information in the same manner as BS 202. Control unit 214 of BS 203 includes the determination information in an Xn setup response message. Alternatively, control unit 214 of BS 203 may not generate the determination information. Control unit 214 of BS 203 may not include the determination information in an Xn setup response message.

[0081] The control unit 214 of the BS 201 acquires the information for determination. The control unit 214 of the BS 201 determines that the RedCap UE and the BS 202 can communicate with each other based on the information for determination received from the BS 202. The control unit 214 of the BS 201 may determine that the RedCap UE and the BS 202 can communicate with each other when the information for determination includes at least one of redCap-AccessAllowed, singleRx-AccessAllowed, and twoRx-AccessAllowed.

[0082] The control unit 214 of the BS 201 determines that the RedCap UE and the BS 203 cannot communicate with each other based on the determination information received from the BS 203. The control unit 214 of the BS 201 may determine that the RedCap UE and the BS 203 cannot communicate with each other when the determination information is not included in the Xn setup response message from the BS 203.

[0083] Step S103: The network communication unit 213 of the BS 201 transmits the NG-RAN node setting update message to the BS 202 and the BS 203. The network communication units 213 of the BS 202 and the BS 203 receive the NG-RAN node setting update message from the BS 201.

[0084] The NG-RAN Node Configuration Update message is a message related to updating the base station configuration. The NG-RAN Node Configuration Update message is sent to initiate the base station configuration update procedure. The NG-RAN Node Configuration Update message is sent to neighboring base stations to update the necessary application level configuration data.

[0085] The control unit 214 of the BS 201 may include, in the NG-RAN node configuration update message, information for determining whether the RedCap UE and the BS 201 can communicate with each other. Details of the information for determination will be described later. The control units 214 of the BSs 202 and 203 may determine that the RedCap UE and the BS 201 can communicate with each other based on the information for determination.

[0086] Step S104: The BS202 and the network communication unit 213 of the BS202 transmit an NG-RAN node setting update acknowledgement message to the BS201. The network communication unit 213 of the BS201 receives an NG-RAN node setting update acknowledgement message including the determination information from each of the BS202 and the BS203.

[0087] The NG-RAN node configuration update acknowledgement message is a message regarding the update of the base station configuration. The NG-RAN node configuration update acknowledgement message is sent when the base station configuration update procedure is successful. The NG-RAN node configuration update acknowledgement message is a response message to the NG-RAN node configuration update message.

[0088] The control unit 214 of the BS 202 may include the determination information in the NG-RAN node configuration update acknowledgement message. The control unit 214 of the BS 203 may include the determination information in the NG-RAN node configuration update acknowledgement message. Alternatively, the control unit 214 of the BS 203 may not generate the determination information. Therefore, the control unit 214 of the BS 203 may not include the determination information in the NG-RAN node configuration update acknowledgement message.

[0089] Similar to step S102, the control unit 214 of the BS 201 may determine that the RedCap UE and the BS 202 can communicate with each other based on the determination information received from the BS 202. The control unit 214 of the BS 201 may determine that the RedCap UE and the BS 202 cannot communicate with each other based on the Xn setup response message.

[0090] Thereafter, the description will proceed assuming that the UE 100 is in an RRC connected state in which there is an RRC connection between the RRC of the UE 100 and the RRC of the base station 200.

[0091] In addition, the control unit 214 of BS201 may receive at least one of information indicating whether UE100 is a RedCap UE or not, information indicating whether UE100 is a RedCap UE having a single receiving branch or not, and information indicating whether UE100 is a RedCap UE having two receiving branches or not from UE100, for example, when establishing an RRC connection with UE100.

[0092] The control unit 214 of the BS 201 may determine, based on the determination information, whether or not to designate cells managed by each of the BSs 202 and 203 as measurement targets for which the UE 100 measures wireless quality.

[0093] When the UE 100 is a RedCap UE, the control unit 214 of the BS 201 designates a cell capable of accepting the RedCap UE. When the UE 100 is a RedCap UE having a single receiving branch, the control unit 214 of the BS 201 designates a cell capable of accepting the RedCap UE having a single receiving branch. When the UE 100 is a RedCap UE having two receiving branches, the control unit 214 of the BS 201 designates a cell capable of accepting the RedCap UE having two receiving branches. The control unit 214 of the BS 201 may include a list of designated cells (e.g., a whitelist) as cells to be measured in the measurement configuration.

[0094] When the UE 100 is a RedCap UE, the control unit 214 of the BS 201 may include the UE 100 in a list of cells that cannot accept RedCap UEs (e.g., a blacklist) as a cell that is not a measurement target. When the UE 100 is a RedCap UE having a single receiving branch, the control unit 214 of the BS 201 may include the UE 100 in a list of cells that cannot accept RedCap UEs having a single receiving branch as a cell that is not a measurement target even if the cell can accept RedCap UEs. When the UE 100 is a RedCap UE having two receiving branches, the control unit 214 of the BS 201 may include the UE 100 in a list of cells that cannot accept RedCap UEs having two receiving branches as a cell that is not a measurement target even if the cell can accept RedCap UEs.

[0095] Step S105: The communication unit 212 of the BS 201 transmits the measurement configuration to the UE 100. The communication unit 120 of the UE 100 receives the measurement configuration. The control unit 130 of the UE 100 measures the radio quality in accordance with the measurement configuration.

[0096] The control unit 130 of the UE 100 measures the wireless quality of the cells included in the list of cells designated as cells to be measured. On the other hand, the control unit 130 of the UE 100 does not measure the wireless quality of the cells included in the list of cells designated as cells not to be measured.

[0097] Step S106: The communication unit 120 of the UE 100 transmits the measurement report to the BS 201. The communication unit 212 of the BS 201 receives the measurement report from the UE 100.

[0098] Step S107: The controller 214 of the BS 201 decides to handover the UE 100 based on the measurement report.

[0099] Also, as shown in Fig. 7 and Fig. 8, the control unit 214 of the BS 201 may determine a cell as a candidate for the handover destination of the UE 100 based on the determination information included in the inter-base station message. When the UE 100 is a RedCap UE, the control unit 214 of the BS 201 determines a cell capable of accepting the RedCap UE as a candidate cell for the handover destination. When the UE 100 is a RedCap UE having a single receiving branch, the control unit 214 of the BS 201 determines a cell capable of accepting the RedCap UE having a single receiving branch as a candidate cell for the handover destination. When the UE 100 is a RedCap UE having two receiving branches, the control unit 214 of the BS 201 determines a cell capable of accepting the RedCap UE having two receiving branches as a candidate cell for the handover destination.

[0100] For example, the control unit 214 of the BS 201 selects a cell having radio quality better than a predetermined reference value from among the candidate cells based on the measurement report as a handover destination cell. In this operation example, the control unit 214 of the BS 201 starts control to transmit a handover request message to the BS 202 that manages the selected cell.

[0101] Step S108: Network communication unit 213 of BS 201 transmits a handover request message to BS 202. Network communication unit 213 of BS 202 receives the handover request message from BS 201.

[0102] The control unit 214 of the BS 202 determines whether or not to approve the handover request. In this operation example, the description will proceed assuming that the control unit 214 of the BS 202 decides to approve the handover request.

[0103] Step S109: Network communication unit 213 of BS 202 transmits the handover request acknowledgement message to BS 201. Network communication unit 213 of BS 201 receives the handover request acknowledgement message from BS 202.

[0104] Step S110: The communication unit 212 of the BS 201 transmits an RRC reconfiguration message for triggering a handover to the UE 100. The communication unit 120 of the UE 100 receives the RRC reconfiguration message from the BS 201.

[0105] In this operation example, the RRC reconfiguration message is a message for handing over the UE 100 to the cell of the BS 202 .

[0106] Step S111: The control unit 130 of the UE 100 detaches from the cell of the BS 201 and synchronizes with the cell of the BS 202.

[0107] Step S112: When the handover procedure is completed, the communication unit 120 of the UE 100 transmits an RRC reconfiguration complete message to the BS 202. The communication unit 212 of the BS 202 receives the RRC reconfiguration complete message from the UE 100.

[0108] (2.2) Example 2 An operation example 2 of the UE 100 and the BS 200 according to the embodiment of the present disclosure will be described with reference to Fig. 9. Differences from the above content will be mainly described. While the operation example 1 describes a case where a general handover is performed, the operation example 2 describes a case where a conditional handover (CHO) is performed.

[0109] Steps S201 to S206: This is the same as steps S101 to S106 in the first operational example.

[0110] Step S207: The control unit 214 of the BS 201 determines to perform a conditional handover to the UE 100.

[0111] Control unit 214 of BS 201 determines the destination of a handover request message for requesting a conditional handover, based on the determination information.

[0112] The control unit 214 of the BS201 may determine a candidate cell as a handover destination of the UE100 based on the determination information in the same manner as in step S107. When the UE100 is a RedCap UE, the control unit 214 of the BS201 determines a cell capable of accepting the RedCap UE as a candidate cell. When the UE100 is a RedCap UE having a single receiving branch, the control unit 214 of the BS201 determines a cell capable of accepting the RedCap UE having a single receiving branch as a candidate cell. When the UE100 is a RedCap UE having two receiving branches, the control unit 214 of the BS201 determines a cell capable of accepting the RedCap UE having two receiving branches as a candidate cell.

[0113] In this operation example, the control unit 214 of the BS 201 determines the BS 202 that manages the candidate cell as the transmission destination (candidate target base station) of the handover request message. On the other hand, the control unit 214 of the BS 201 determines not to transmit the handover request message to the BS 203 that does not manage the candidate cell.

[0114] Step S208: Network communication unit 213 of BS 201 transmits a handover request message for each candidate cell to BS 202. Network communication unit 213 of BS 202 receives the handover request message for each candidate cell from BS 201.

[0115] Control unit 214 of BS 202 determines whether to approve the handover request, similar to step S108.

[0116] Step S209: The network communication unit 213 of the BS 202 transmits a handover request acknowledgement message including a conditional handover candidate cell setting for each candidate cell to the BS 201. The network communication unit 213 of the BS 201 receives the handover request acknowledgement message from the BS 202.

[0117] Step S210: The communication unit 212 of the BS 201 transmits the RRC reconfiguration message to the UE 100. The communication unit 120 of the UE 100 receives the RRC reconfiguration message from the BS 201.

[0118] The RRC reconfiguration message includes a conditional handover candidate cell configuration and a conditional handover execution condition.

[0119] Step S211: The communication unit 120 of the UE 100 transmits an RRC reconfiguration complete message to the BS 201. The communication unit 212 of the BS 201 receives the RRC reconfiguration complete message from the UE 100.

[0120] Step S212: The control unit 130 of the UE 100 starts to evaluate the conditional handover execution condition. After receiving the configuration of the conditional handover candidate cell, the control unit 130 of the UE 100 maintains the RRC connection with the BS 201.

[0121] Step S213: When a candidate cell satisfies a corresponding conditional handover execution condition, the control unit 130 of the UE 100 detaches from the cell of the BS 201 and synchronizes with the candidate cell.

[0122] Step S214: When the handover procedure is completed, the communication unit 120 of the UE 100 transmits an RRC reconfiguration complete message to the BS 202. The communication unit 212 of the BS 202 receives the RRC reconfiguration complete message from the UE 100.

[0123] Step S215: If the handover is successful, network communication unit 213 of BS 202 transmits a handover success message to BS 201. Network communication unit 213 of BS 201 receives the handover success message from BS 202.

[0124] (Other embodiments) Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the embodiment. For example, the inter-base station message may be a message other than the above-mentioned message.

[0125] In addition, in each of the above operation examples, singleRx-AccessAllowed is information about a single reception branch, but is not limited to this. singleRx-AccessAllowed may be information about any of a single reception chain, a single receiver, and a single reception antenna port. Therefore, in each of the above operation examples, the "single reception branch" may be replaced with a "single reception chain," a "single receiver," and a "single reception antenna port."

[0126] In addition, in each of the above operation examples, twoRx-AccessAllowed is information about two reception branches, but is not limited to this. SingleRx-AccessAllowed may be information about any of two reception chains, two receivers, and two reception antenna ports. Therefore, in each of the above operation examples, "two reception branches" may be replaced with "two reception chains," "two receivers," and "two reception antenna ports."

[0127] In addition, the above-mentioned operation examples are not limited to being performed separately and independently, but may be performed by appropriately combining the operation examples. For example, the steps in the process described in this specification do not necessarily have to be performed in chronological order according to the order described in the flowchart or sequence diagram. For example, the steps in the process may be performed in an order different from the order described in the flowchart or sequence diagram, or may be performed in parallel. In addition, some of the steps in the process may be deleted, and further steps may be added to the process.

[0128] For example, a method including the operation of one or more components of the apparatus described in this specification may be provided, or a program for causing a computer to execute the operation of the components may be provided. Also, a non-transitory tangible computer-readable storage medium having the program recorded thereon may be provided. Such a method, program, and non-transitory tangible computer-readable storage medium are also included in the present disclosure. Also, at least a part of the UE 100 or at least a part of the BS 200 may be a chipset or SoC (System on Chip) in which circuits for executing each process performed by the UE 100 or the BS 200 are integrated.

[0129] In the present disclosure, "transmit" may mean performing processing of at least one layer in a protocol stack used for transmission, or may mean physically transmitting a signal wirelessly or via a wire. Alternatively, "transmit" may mean a combination of performing processing of at least one layer and physically transmitting a signal wirelessly or via a wire. Similarly, "receive" may mean performing processing of at least one layer in a protocol stack used for reception, or may mean physically receiving a signal wirelessly or via a wire. Alternatively, "receive" may mean a combination of performing processing of at least one layer and physically receiving a signal wirelessly or via a wire.

[0130] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments. It will be understood by those skilled in the art that the embodiments are merely examples and that various modifications are possible without departing from the scope and spirit of the present disclosure. [Explanation of symbols]

[0131] 1: Mobile communication systems 100: User equipment (UE, RedCap UE) 120: Communications Department 121: Receiving unit 122: Transmitter 130: Control section 200: Base station (BS) 211: Antenna 212: Communications Department 212a: Receiving section 212b: Transmitter 213: Network Communication Department 214: Control section 300: Core network equipment

Claims

1. A base station, A network communication unit that receives an Xn setup request message from another base station, the Xn setup request message including information indicating that the cell of the other base station supports a Reduced Capability (RedCap) user equipment; The information indicating that the cell supports the RedCap user equipment includes first information indicating whether the RedCap user equipment having a single receive branch can access the cell, and second information indicating whether the RedCap user equipment having two receive branches can access the cell. Base station.

2. and a control unit configured to determine a target for handover of the RedCap user equipment based on at least one of the information indicating that the cell supports the RedCap user equipment, the first information, and the second information. The base station according to claim 1 .

3. The network communication unit transmits an Xn setup response message to the other base station; Whether the cell of the base station supports the RedCap user equipment is indicated based on whether the Xn setup response message includes information indicating that the cell of the base station supports the RedCap user equipment. A base station as claimed in claim 1 or 2.

4. The network communication unit transmits a configuration update message to the other base station, the configuration update message including information indicating that the cell of the base station supports the RedCap user equipment. A base station as claimed in claim 1 or 2.

5. A communication method implemented in a base station, comprising: receiving an Xn setup request message from another base station, the Xn setup request message including information indicating that the cell of the other base station supports a Reduced Capability (RedCap) user equipment; The information indicating that the cell supports the RedCap user equipment includes first information indicating whether the RedCap user equipment having a single receive branch can access the cell, and second information indicating whether the RedCap user equipment having two receive branches can access the cell. Communication methods.

6. determining a target for handover of the RedCap user equipment based on at least one of the information indicating that the cell supports the RedCap user equipment, the first information, and the second information. The communication method according to claim 5.

7. sending a Xn setup response message to the other base station; Whether the cell of the base station supports the RedCap user equipment is indicated based on whether the Xn setup response message includes information indicating that the cell of the base station supports the RedCap user equipment. The communication method according to claim 5 or 6.

8. sending a configuration update message to the other base station including information indicating that the cell of the base station supports the RedCap user equipment. The communication method according to claim 5 or 6.

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