JP2022164264A - User device and communication control method - Google Patents

Abstract

To provide a communication control method and a user device that allow the user device to monitor paging from a second network while maintaining communication with a first network.SOLUTION: In a mobile communication system, a user device that communicates with a plurality of networks by using a plurality of subscriber identification modules, includes: a first receiving unit that receives a wireless signal in a first frequency band; and a second receiving unit that receives a wireless signal in a second frequency band. When the first receiving unit is being used for communication with a first network included in the plurality of networks S201 YES, in a selection operation of selecting a camp-on cell in which a user device is located in a second network included in the plurality of networks, priority control of preferentially selecting a cell belonging to the second frequency band over a cell belonging to the first frequency band is performed S202.SELECTED DRAWING: Figure 7

Description

The present invention relates to a user equipment and communication control method used in a mobile communication system.

In Release 17 of 3GPP (3rd Generation Partnership Project), which is a standardization project for mobile communication systems, a function for a user device equipped with multiple subscriber identification modules to perform data communication while being in the network of multiple carriers. A work item has been launched to formulate

Currently, there is no provision in the standard specifications for a mechanism for receiving paging (that is, incoming calls) for user devices that are present in multiple networks, and it depends on the implementation of the user device. When the user device includes a plurality of receivers (RX: Receivers), one receiver is used for communication with one network (hereinafter referred to as "first network"), and the other receiver is used for communication with the other network. Paging can be monitored in the network (hereinafter "second network").

However, when the user device has only one receiving unit, if there is an incoming call from the second network while one receiving unit is communicating with the first network, the user device may miss the incoming call. become. Therefore, in order for the user device to monitor the paging of the second network while maintaining the connection with the first network, the first network sets the user device to an interruption period during which communication with the first network can be temporarily interrupted. A method for doing so is being considered in the 3GPP standardization arena (see, for example, Non-Patent Document 1). Such interruption periods are sometimes referred to as "gap."

3GPP contributions "R2-2100474"

The frequency ranges for receiving radio signals may differ among the plurality of receivers provided in the user equipment. For example, assume a case where the user equipment includes a first receiver that receives radio signals in a first frequency band and a second receiver that receives radio signals in a second frequency band.

In such a case, when the first receiving unit is used for communication with the first network included in the plurality of networks, the camp-on cell in which the user device is located in the second network included in the plurality of networks In the selection operation, if a cell belonging to a frequency of the first frequency band that the second receiver cannot receive is selected, the first receiver must be used to monitor paging from the second network. Although the user equipment is equipped with multiple receivers, it is necessary to set gaps in the user equipment since effectively only one receiver can be used. The user equipment has to interrupt communication with the first network during the period in which the gap is set, and there is a problem that the performance of communication with the first network is degraded.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a user device and a communication control method capable of monitoring paging from a second network while maintaining communication with the first network.

A user device according to a first aspect is a user device that communicates with a plurality of networks using a plurality of subscriber identification modules, and includes a first receiver that receives a radio signal in a first frequency band, a second frequency When the first receiving unit is used for communication between a second receiving unit that receives radio signals in a band and a first network included in the plurality of networks, in the second network included in the plurality of networks A control unit that performs priority control to select a cell belonging to the second frequency band with priority over a cell belonging to the first frequency band in a selection operation for selecting a camp-on cell where the user equipment is located. Prepare.

A communication control method according to a second aspect is a communication control method executed by a user device that communicates with a plurality of networks using a plurality of subscriber identification modules, wherein a first receiving unit of the user device: receiving radio signals in one frequency band; receiving radio signals in a second frequency band by a second receiving unit of the user equipment; When the first receiving unit is used, in the selection operation of selecting the camp-on cell where the user equipment is located in the second network included in the plurality of networks, the cell belonging to the first frequency band rather than the cell belonging to the first frequency band and performing priority control for preferentially selecting a cell belonging to the second frequency band.

According to one aspect of the present invention, it is possible to provide a user device and communication control method capable of monitoring paging from a second network while maintaining communication with the first network.

1 is a diagram showing the configuration of a mobile communication system according to an embodiment; FIG. It is a figure which shows the structural example of the protocol stack of the mobile communication system which concerns on embodiment. It is a figure which shows the structural example of UE which concerns on embodiment. It is a figure explaining the receiving part of UE which concerns on embodiment. FIG. 3 is a diagram showing a configuration example of a base station of the first network according to the embodiment; It is a figure which shows the operation example of the mobile communication system which concerns on embodiment. FIG. 5 is a diagram illustrating an example of selection operation of the UE according to the embodiment;

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

(System configuration)
A configuration of a mobile communication system 1 according to an embodiment will be described with reference to FIG. An example in which the mobile communication system 1 is a 3GPP standard fifth generation system (5G/NR: New Radio) will be mainly described below, but the mobile communication system 1 includes a fourth generation system (4G/LTE: Long Term Evolution) system and/or 6th generation system may be applied at least partially.

As shown in FIG. 1, the mobile communication system 1 according to the embodiment has a user equipment (UE) 100, a first network 200A, and a second network 200B.

UE 100 is a mobile wireless communication device. The UE 100 may be a device used by a user, but for example, the UE 100 may be a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC, a communication module (including a communication card or chipset), a sensor, or a sensor. a vehicle or a device installed in a vehicle (Vehicle UE); an aircraft or a device installed in an aircraft (Aerial UE).

The UE 100 is a multi-SIM device that supports multiple subscriber identity modules (SIMs). An example in which the UE 100 supports two SIMs will be mainly described below, but the UE 100 may support three or more SIMs. “Supporting multiple SIMs” means that the UE 100 has the ability to handle multiple SIMs, and the UE 100 does not necessarily have to be equipped with multiple SIMs. Such a UE 100 is sometimes called a "UE that supports multiple SIMs". Note that the SIM is not limited to a card-type SIM (so-called SIM card), and may be an embedded SIM (so-called eSIM) pre-installed in the UE 100 . The SIM is sometimes called a USIM (Universal Subscriber Identity Module).

A first network 200A is a network associated with one SIM of the UE 100 . A second network 200B is a network associated with the other SIM of the UE 100 . It is assumed that UE 100 performs location registration with first network 200A using one SIM, and performs location registration with second network 200B using the other SIM. That is, UE 100 is located in each of first network 200A and second network 200B. The first network 200A and the second network 200B may be networks of different carriers. However, the first network 200A and the second network 200B may be networks of the same carrier. Different PLMN (Public Land Mobile Network) IDs may be assigned to the first network 200A and the second network 200B.

The first network 200A has a base station 210A and a core network 220A that constitute a radio access network. The core network 220A has a mobility management device 221A and a gateway device 222A. Similarly, the second network 200B has a base station 210B and a core network 220B forming a radio access network. The core network 220B has a mobility management device 221B and a gateway device 222B. Hereinafter, when the base stations 210A and 200B are not distinguished, they are simply referred to as the base station 210; when the mobility management devices 221A and 221B are not distinguished, they are simply referred to as the mobility management device 221; It is called gateway device 222 .

The base station 210 is a radio communication device that performs radio communication with the UE 100 . A base station 210 manages one or more cells. The base station 210 performs radio communication with the UE 100 that has established a connection in the radio resource control (RRC) layer with its own cell. The base station 210 has a radio resource management (RRM) function, a user data (hereinafter simply referred to as “data”) routing function, a measurement control function for mobility control/scheduling, and the like. A "cell" is used as a term indicating the minimum unit of a wireless communication area. A “cell” is also used as a term indicating a function or resource for radio communication with the UE 100 . One cell belongs to one carrier frequency. FIG. 1 shows an example in which the base station 210A manages the cell C1 and the base station 210B manages the cell C2. The UE 100 is located in the overlapping area of cell C1 and cell C2.

A frame used in wireless communication between the UE 100 and the base station 210 is, for example, 10 ms, and each frame is assigned a system frame number (SFN). Each frame is divided into, for example, 1 ms subframes, and each subframe consists of a plurality of OFDM symbols.

The base station 210 may be a gNB, which is a 5G/NR base station, or an eNB, which is a 4G/LTE base station. In the following, an example in which the base station 210 is a gNB will be mainly described. The base station 210 may be functionally divided into a CU (Central Unit) and a DU (Distributed Unit). Base station 210 may be a relay node such as an IAB (Integrated Access and Backhaul) node.

The mobility management device 221 is a device that supports the control plane and performs various types of mobility management for the UE 100 . The mobility management device 221 communicates with the UE 100 using NAS (Non-Access Stratum) signaling and manages information on the tracking area in which the UE 100 is located. The mobility management device 221 performs paging through the base station 210 to notify the UE 100 of the incoming call. The mobility management device 221 may be a 5G/NR AMF (Access and Mobility Management Function) or a 4G/LTE MME (Mobility Management Entity).

The gateway device 222 is a device compatible with the user plane, and is a device that performs data transfer control of the UE 100 . The gateway device 222 may be a 5G/NR UPF (User Plane Function) or a 4G/LTE S-GW (Serving Gateway).

(Example of protocol stack configuration)
A configuration example of the protocol stack of the mobile communication system 1 will be described with reference to FIG.

As shown in FIG. 2, the protocol of the radio section between the UE 100 and the base station 210 includes a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Convergence Protocol) layer and RRC layer.

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 210 via physical channels.

The MAC layer performs data priority control, hybrid ARQ (HARQ) retransmission processing, random access procedures, and the like. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the base station 210 via transport channels. The MAC layer of base station 210 includes a scheduler. The scheduler determines uplink and downlink transport formats (transport block size, modulation and coding scheme (MCS)) and allocation resources to the UE 100 .

The RLC layer uses functions of the MAC layer and the PHY layer to transmit data to the RLC layer of the receiving side. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the base station 210 via logical channels.

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

An SDAP (Service Data Adaptation Protocol) layer may be provided as an upper layer of the PDCP layer. The SDAP (Service Data Adaptation Protocol) layer performs mapping between an IP flow, which is a unit of QoS control performed by a core network, and a radio bearer, which is a unit of QoS control performed by an AS (Access Stratum).

The RRC layer controls logical, transport and physical channels according to 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 210 . If there is an RRC connection between the RRC of UE 100 and the RRC of base station 210, UE 100 is in the RRC connected state. If there is no RRC connection between the RRC of the UE 100 and the RRC of the base station 210, the UE 100 is in RRC idle state. When the RRC connection between the RRC of UE 100 and the RRC of base station 210 is suspended, UE 100 is in RRC inactive state.

The NAS layer located above the RRC layer performs session management and mobility management for the UE 100 . NAS signaling is transmitted between the NAS layer of UE 100 and the NAS layer of mobility management device 221 .

Note that the UE 100 has an application layer and the like in addition to the radio interface protocol.

(Outline of selection operation)
UE 100 can perform a cell selection operation or a cell reselection operation as a selection operation to select a camp-on cell. The UE 100 can perform the selection operation, for example, in any of the following cases.

・When a new PLMN or a new SNPN (Stand-alone Non-Public Network) is selected ・When a USIM is inserted into the UE 100 or when an SNPN subscription is added ・A suitable cell is found If not - When transitioning from RRC connected state to RRC idle state or RRC inactive state

(A) Cell selection operation In the cell selection operation, UE 100 searches the frequency band, the strongest cell for each frequency (eg, CD-SSB (cell-defining SS / PBCH Block) cell with the highest detection level, Identify the cell with the highest CD-SSB received power (RSRP) or the highest CD-SSB received quality (RSRQ). The UE 100 then identifies a suitable cell among the strongest cells. If the UE 100 cannot identify a suitable cell (that is, no suitable cell is found), it identifies an acceptable cell. UE 100 selects a suitable cell as a camp-on cell, if a suitable cell can be identified (that is, a suitable cell is found). UE 100 selects an allowable cell as a camp-on cell if only an allowable cell can be identified (that is, an allowable cell is found).

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

Cell selection criteria are, for example, Srxlev>0 and Squal>0. Srxlev represents cell selection received power. Srxlev is calculated by Srxlev = Q _rxlevmeas - (Q _rxlevmin + Q _{rxlevminoffset} ) - P _compensation - Qoffset _temp . Q _rxlevmeas is the measured cell received power (RSRP). 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 uplink capability. Qoffset _temp is the offset applied temporarily. Squal represents the cell selection quality level. Squal is calculated by Squal = Q _qualmeas - (Q _qualmin + Q _{qualminoffset} ) - Qoffset _temp . Q _qualmeas is the measured cell quality level (RSRQ). Q _qualmin is the minimum required quality level. Q _{qualminoffset} is a predetermined offset that is constantly applied. Qoffset _temp is the offset applied temporarily.

(B) Cell reselection operation In cell reselection operation, UE 100 measures the communication quality of the serving cell and neighboring cells. UE 100 selects a camp-on cell to be used as a serving cell, for example, based on the following criteria. UE 100 determines the priority of the cell to be selected based on the frequency priority. UE 100 may select a camp-on cell based on the following criteria when 1 second or more has elapsed since camping on the current serving cell.

(B1) Neighboring cell's frequency priority is higher than current serving cell's frequency priority:
UE 100 selects a cell that satisfies the relationship of Squal>Thresh X, _HighQ over a predetermined period (eg, Treselection _RAT ) or a cell that satisfies the relationship of Srxlev>Thresh _{X, HighP} over a predetermined period. Each of Thresh _{X, HighP} and Thresh _{X, HighQ} is a predetermined threshold.

(B2) the neighboring cell's frequency priority is the same as the current serving cell's frequency priority:
The UE 100 calculates the current serving cell ranking Rs and the neighboring cell ranking Rn. The UE 100 selects a cell having a ranking Rn higher than Rs over a predetermined period as a camp-on cell.

Rs is calculated by Rs=Q _meas,s +Q _hyst -Qoffset _temp . Rn is calculated by Rn=Q _meas,n -Qoffset-Qoffset _temp . Q _meas,s is the current serving cell received power (RSRP). Q _meas,n is the neighbor cell received power (RSRP). Q _hyst is a hysteresis value for facilitating reselection of the current serving cell. Qoffset _temp is the offset applied temporarily.

(B3) the neighboring cell's frequency priority is lower than the current serving cell's frequency priority:
Under the premise that the serving cell satisfies the relationship Squal<Thresh _{Serving, LowQ} or Srxlev<Thresh _{Serving, LowP} over a predetermined period, the UE 100 satisfies the relationship Squal>Thresh _{X, LowQ} over a predetermined period. Alternatively, a cell that satisfies the relationship Srxlev>Thresh _{X, LowP} over a predetermined period is selected. Each of Thresh _{X, LowP} and Thresh _{X, Low Q} is a predetermined threshold.

Various parameters used in cell selection are included in information (SIB: System Information Block) broadcast from the base station 210 . Various parameters include frequency priority (e.g., cellReselectionPriority, cellReselectionSubPriority), predetermined period (Treselection _RAT ), various offsets (Q _{qualminoffset} , Qrxlevminoffset, Q _offsettemp , Q _{hyst , XQTh} , _Qth , various thresholds) _{ThreshX,HighP} , _{ThreshServing,LowQ} , _{ThreshServing,LowP, ThreshX ,LowP, ThreshX ,LowQ} ). cellReselectionPriority indicates the frequency priority in 8 levels, and cellReselectionSubPriority indicates the frequency sub-priority in 4 levels. As a result, up to 32 levels of priority can be set in the UE 100 for frequencies. The frequency priority may be notified to the UE 100 in an RRC release message. The frequency priority notified in the RRC release message can specify multiple frequency priorities in a list format. The priority of that frequency takes precedence over the priority of the broadcast frequency. Based on the information received from the base station 210, the UE 100 performs a selection operation of selecting a camp-on cell.

Note that the RRC release message may include carrier information specifying a frequency (so-called redirectedCarrierInfo). Carrier information takes precedence over frequency priority. UE 100 preferentially selects a cell belonging to the frequency specified by the carrier information, regardless of frequency priority.

(UE configuration example)
A configuration example of the UE 100 will be described with reference to FIGS. 3 and 4. FIG. As shown in FIG. 3 , UE 100 has antenna 101 , antenna 102 , SIM 111 , SIM 112 , communication section 120 and control section 130 . Antenna 101 and antenna 102 may be provided outside the UE 100 . Antenna 101 may be used for first communication section 120A, which will be described later, and antenna 102 may be used for second communication section 120B, which will be described later. SIM 111 and SIM 112 are SIM cards or eSIMs.

The SIM 111 stores subscriber information and setting information necessary for the UE 100 to communicate with the first network 200A. The SIM 111 stores identification information of the UE 100 in the first network 200A, such as a telephone number and an IMSI (International Mobile Subscriber Identity).

The SIM 112 stores subscriber information and setting information necessary for the UE 100 to communicate with the second network 200B. The SIM 112 stores identification information of the UE 100 in the second network 200B, such as telephone number and IMSI.

The communication unit 120 performs wireless communication with the first network 200A and wireless communication with the second network 200B via the antenna 101 under the control of the control unit 130 . The communication unit 120 communicates with multiple networks using multiple SIMs. The communication unit 120 has a first communication unit 120A and a second communication unit 120B. The communication unit 120 has a plurality of receivers (RX: Receiver) 121 . In this embodiment, the first communication section 120A includes a first reception section 121A, and the second communication section 120B includes a second reception section 121B. The communication unit 120 has a plurality of transmission units (TX: Transmitter) 122 . The communication section 120 may have only one transmission section 122 . In this embodiment, the first communication section 120A includes a first transmission section 122A, and the second communication section 120B includes a second transmission section 122B. Receiving section 121 converts a radio signal received by antenna 101 into a received signal that is a baseband signal, performs signal processing on the received signal, and outputs the received signal to control section 130 . Transmitter 122 performs signal processing on a transmission signal, which is a baseband signal output from controller 130 , converts the signal into a radio signal, and transmits the radio signal from antenna 101 .

As shown in FIG. 4, the frequency range for receiving radio signals in first receiving section 121A differs from the frequency range for receiving radio signals in second receiving section 121B. The first receiver 121A receives radio signals in the first frequency band. The first receiver 121A supports reception of radio signals in the first frequency band, and does not support reception of radio signals in bands other than the first frequency band. The second receiver 121B receives radio signals in the second frequency band. The second receiver 121B supports reception of radio signals in the second frequency band, and does not support reception of radio signals in bands other than the second frequency band. The first frequency band and the second frequency band partially overlap. Therefore, the frequency that can be received by the first receiving unit 121A (that is, the frequency that cannot be received by the second receiving unit 121B), the frequency that can be received by the first receiving unit 121A and the second receiving unit 121B, and the second receiving unit There are frequencies that can be received by the section 121B (that is, frequencies that cannot be received by the first receiving section 121A). For example, in FIG. 4, the first frequency band includes frequency A and frequency B; The second frequency band includes frequency B and frequency C. In this case, the first receiver 121A can receive radio signals on each of frequency A and frequency B, but cannot receive radio signals on frequency C. The second receiver 121B can receive radio signals on each of frequency B and frequency C, but cannot receive radio signals on frequency A.

The control unit 130 controls the communication unit 120 and performs various controls in the UE 100 . Control unit 130 uses SIM 111 to control communication with first network 200A and uses SIM 112 to control communication with second network 200B. Control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for 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), which performs digital processing of digital signals, and a central processing unit (CPU), which executes programs. Note that part of the memory may be provided in the communication unit 120 . Also, the DSP may be provided in the communication unit 120 .

In the UE 100 configured in this way, the communication unit 120 communicates with the base station 210A of the first network 200A. For example, it is assumed that UE 100 is in the RRC connected state in cell C1 of base station 210A of first network 200A. It is also assumed that the UE 100 is in the RRC idle state or RRC inactive state in cell C2 of the base station 210B of the second network 200B. Such a cell C2 may be called a camp-on cell for the UE 100. UE 100 is located in a camp-on-cell.

When first receiving unit 121A is used for communication with first network 200A, control unit 130 selects a camp-on cell where UE 100 is located in second network 200B in the first frequency band. Priority control is performed to preferentially select a cell belonging to the second frequency band over the cell to which it belongs. Thereby, when the first receiving unit 121A is used for communication with the first network 200A, the UE 100 belongs to the second frequency band rather than the cell belonging to the first frequency band received by the first receiving unit 121A. It becomes easier to select a cell as a camp-on cell. By selecting a cell belonging to the second frequency band as a camp-on cell, while maintaining communication with the first network 200A in the first receiver 121A, paging from the second network 200B in the second receiver 121B can be monitored. Note that "communication with the first network 200A" may be communication with the first network 200A in the RRC connected state, or communication with the first network 200A in the RRC idle state or RRC inactive state (for example, , monitoring of paging).

In addition, the control unit 130 gives priority to the frequencies included in the first frequency band as lower priority than the priorities of the frequencies included in the second frequency band as the priority of the frequencies in the selection operation. control. As a result, cells belonging to frequencies included in the first frequency band received by the first receiving unit 121A are less likely to be selected, and cells belonging to the second frequency band are more likely to be selected as camp-on cells.

The control unit 130 may perform priority control so that the priority of the frequencies included in the first frequency band is regarded as the lowest priority as the priority of the frequencies in the selection operation. As a result, cells belonging to frequencies included in the first frequency band received by the first receiving unit 121A are less likely to be selected, and cells belonging to the second frequency band are more likely to be selected as camp-on cells. Therefore, if the UE 100 has multi-SIM capability to support multiple SIMs, has multiple receivers 121, and has already camped on the first network 200A with SIM 111, the UE 100 can use SIM 112 The frequency camped on may be considered the lowest priority.

Note that the lowest priority may be, for example, the 32nd priority among the 32 levels of priority indicated by cellReselectionPriority and cellReselectionSubPriority. Alternatively, the lowest priority may be a priority lower than the lowest priority set by the network.

The control unit 130 performs priority control so that the priority of the frequency used for communication with the first network 200A among the frequencies included in the first frequency band is regarded as the lowest priority as the frequency priority in the selection operation. may be performed. As a result, cells belonging to the frequency used for communication with the first network 200A are less likely to be selected, and cells belonging to the second frequency band are more likely to be selected as camp-on cells.

The control unit 130 performs priority control so that the priority of the frequency that does not overlap with the second frequency band among the frequencies included in the first frequency band is regarded as the lowest priority as the priority of the frequency in the selection operation. good. As a result, it becomes difficult for cells belonging to frequencies included in the first frequency band to be received by the first receiving unit 121A to be selected, while frequencies included in the first frequency band are received by the second receiving unit 121B. It is possible to prevent even cells belonging to frequencies included in the second frequency band from being difficult to be selected. This makes it easier to select a cell belonging to the second frequency band as a camp-on cell.

As the frequency priority in the selection operation, the control unit 130 performs priority control so that the priority of the frequency included in the second frequency band is regarded as higher than the priority of the frequency included in the first frequency band. you can go This makes it easier to select a cell belonging to the second frequency band as a camp-on cell.

As the frequency priority in the selection operation, the control unit 130 sets the priority of the frequencies included in the second frequency band higher than the frequencies included in the first frequency band that do not overlap with the second frequency band. Priority control may be performed so as to regard it as priority. As a result, it becomes easier to select the cell belonging to the second frequency band as the camp-on cell than the cell belonging to the frequency included in the first frequency band, while the second receiving unit 121B among the frequencies included in the first frequency band It is possible to avoid the difficulty of selecting even a cell belonging to a frequency included in the second frequency band received at .

The control unit 130 may perform priority control so that the priority of frequencies included in the second frequency band is regarded as the highest priority as the priority of frequencies in the selection operation. This makes it easier to select cells belonging to the second frequency band as camp-on cells than cells belonging to frequencies included in the first frequency band.

The control unit 130 may perform priority control so that a cell belonging to the frequency used for communication with the first network 200A is regarded as a prohibited cell that is prohibited from being selected as a camp-on cell. As a result, cells belonging to the frequency used for communication with the first network 200A are not selected, making it easier to select cells belonging to the second frequency band as camp-on cells.

In the following, functional units provided in the UE 100 (specifically, the communication unit 120, the first communication unit 120A and the second communication unit 120B, the first reception unit 121A, the second reception unit 121B, the first transmission unit 122A, The operation of at least one of the second transmission unit 122B and the control unit 130) may be described as the operation of the UE 100.

(Base station configuration example)
A configuration example of the base station 210A of the first network 200A will be described with reference to FIG. Note that the base station 210B of the second network 200B has the same configuration as the base station 210A, so description thereof will be omitted. As shown in FIG. 5, the base station 210A has an antenna 211, a communication section 212, a network interface 213, and a control section 214.

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 212 a converts a radio signal received by the antenna 211 into a received signal that is a baseband signal, performs signal processing on the received signal, and outputs the received signal to the control unit 214 . The transmission unit 212 b performs signal processing on a transmission signal, which is a baseband signal output from the control unit 214 , converts the signal into a radio signal, and transmits the radio signal from the antenna 211 .

Network interface 213 is connected to core network 220A. Network interface 213 performs network communication with mobility management device 221A and gateway device 222A under the control of control unit 214 .

The control unit 214 controls the communication unit 212 and performs various controls in the base station 210A. Control unit 214 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for 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), which performs digital processing of digital signals, and a central processing unit (CPU), which executes programs. Note that part of the memory may be provided in the communication unit 212 . Also, the DSP may be provided in the communication unit 212 .

In the following, the operation of the functional unit (specifically, at least one of the communication unit 212, the network interface 213, and the control unit 214) included in the base station 210 may be described as the operation of the base station 210. .

(Operation of mobile communication system)
An operation example of the mobile communication system 1 will be described with reference to FIGS. 6 and 7. FIG. In the following operation description, the UE 100 is in the RRC connected state in cell C1 of the base station 210A of the first network 200A, and is in the RRC idle state or RRC inactive state in the cell C2 of the base station 210B of the second network 200B. shall be UE 100 has established an RRC connection in cell C1 belonging to the first frequency band in first network 200A. UE 100 uses first receiver 121A for communication with first network 200A. The first receiver 121A receives radio signals in the first frequency band. The UE 100 is located (that is, camped) in the cell C2 belonging to the first frequency band or the second frequency band in the second network 200B. The second receiver 121B receives radio signals in the second frequency band. Note that cell C2 is a serving cell in the second network 200B.

Step S101:
The UE 100 measures communication quality in the second network 200B. The UE 100 (control unit 130) may measure the communication quality (for example, received power, received quality, etc.) used in the selection operation in step S102 described later for each frequency. The UE 100 (control unit 130) may measure communication quality at frequencies higher than the priority of cell C2. UE 100 (control unit 130), when the communication quality of cell C2 is below a predetermined threshold, may measure the communication quality in a frequency having the same priority or lower priority than the priority of cell C2.

Step S102:
The UE 100 performs selection operation to select a camp-on cell in the second network 200B. Details of the selection operation will be described later.

Step S103:
UE 100 is located in a cell belonging to the second frequency band. Specifically, UE 100 (control unit 130) is located in a cell belonging to the second frequency band, which is the cell selected in the selection operation, as cell C2 in second network 200B. UE 100 (second receiving unit 121B) residing in cell C2 monitors paging, for example. Paging monitoring is to check whether or not there is paging addressed to UE 100 by receiving a PDCCH (Physical Downlink Control CHannel) from base station 210B of second network 200B. Since UE 100 (control unit 130) uses second receiving unit 121B for communication with second network 200B, it is possible to monitor paging from second network 200B while maintaining communication with first network 200A.

Next, a selection operation example will be described with reference to FIGS. 4 and 7. FIG.

Step S201:
UE 100 (control unit 130) determines whether or not first receiving unit 121A is used for communication with first network 200A. When the UE 100 (the control unit 130) determines that the first reception unit 121A is used for communication with the first network 200A (YES), the UE 100 (control unit 130) executes the process of step S202. When the UE 100 (control unit 130) determines that the first reception unit 121A is not used for communication with the first network 200A (NO), it executes the process of step S203.

For example, the UE 100 (control unit 130) may determine that the first reception unit 121A is used for communication with the first network 200A in at least one of the following cases.
- The first receiver 121A receives a radio signal from the base station 210A of the first network 200A.
- The first receiver 121A monitors radio signals from the base station 210A of the first network 200A.
- In the first network 200, the UE 100 is in one of the RRC connected state, RRC idle state, and RRC inactive state.
- The UE 100 is performing location registration with the first network 200A.
A state in which the UE 100 has found a suitable cell (a so-called “Camped normally” state), that is, a state in which the UE 100 is located (that is, camps) in a suitable cell.

For example, the UE 100 (control unit 130) may determine that the first reception unit 121A is not used for communication with the first network 200A in at least one of the following cases.
- The first receiver 121A cannot receive a radio signal from the base station 210A of the first network 200A.
- The UE 100 has not performed location registration with the first network 200A.
- The UE 100 is in a state where it has not found a suitable cell (for example, "Any Cell Selection" state), that is, it is not located in a suitable cell.

Step S202:
UE 100 (control unit 130) prioritizes cells belonging to the second frequency band in which second receiving unit 121B receives radio signals over cells belonging to the first frequency band in which first receiving unit 121A receives radio signals. to perform priority control for selection. The UE 100 (control unit 130) may perform at least one of the following (a) to (j) as priority control. In the following, as shown in FIG. 4, the case where the first frequency band includes frequency A and frequency B and the second frequency band includes frequency B and frequency C will be described as an example. The “frequency” here is the frequency indicated by the frequency identifier received from the base station 210B. “Frequency” may be a frequency whose communication quality is measured by the UE 100.

(a) UE 100 (control unit 130) regards the priority of frequencies included in the first frequency band as lower priority than the priority of frequencies included in the second frequency band. The frequencies included in the first frequency band may be all frequencies included in the first frequency band, or may be some frequencies included in the first frequency band.

Specifically, UE 100 (control unit 130) considers the priority of frequency A to be lower than the priority of frequency C. The UE 100 (control unit 130) may consider the priority of frequency B to be lower than the priority of frequency C.

UE 100 (control unit 130), when a plurality of frequencies are included in the second frequency band, the priority of the frequency included in the first frequency band, among the priority of a plurality of frequencies included in the second frequency band It may be considered a lower priority than the lowest priority.

(b) UE 100 (control unit 130) sets the priority of a frequency (hereinafter referred to as a first non-overlapping frequency as appropriate) that does not overlap with the second frequency band among the frequencies included in the first frequency band to the second It may be regarded as a priority lower than the priority of frequencies included in the frequency band. The first non-overlapping frequencies may be all frequencies included in the first frequency band that do not overlap with the second frequency band, or may be all frequencies included in the first frequency band that do not overlap with the second frequency band. It may be some frequencies that do not overlap with the frequency band.

Specifically, UE 100 (control unit 130) considers the priority of frequency A to be lower than the priority of frequency C. On the other hand, UE 100 (control unit 130) maintains the priority of frequency B without considering the priority of frequency B to be lower than the priority of frequency C.

(c) UE 100 (control unit 130) regards the priority of frequencies included in the first frequency band as the lowest priority. The frequencies included in the first frequency band may be all frequencies included in the first frequency band, or may be some frequencies included in the first frequency band.

Specifically, UE 100 (control unit 130) regards the priority of frequency A as the lowest priority. UE 100 (control unit 130) may regard the priority of frequency B as the lowest priority.

(d) UE 100 (control unit 130) regards the priority of the frequency used for communication with first network 200A among the frequencies included in the first frequency band as the lowest priority. Specifically, when UE 100 (control unit 130) uses frequency A for communication with first network 200A, UE 100 regards the priority of frequency A as the lowest priority.

(e) UE 100 (control unit 130) regards the priority of a frequency (first non-overlapping frequency) that does not overlap with the second frequency band among the frequencies included in the first frequency band as the lowest priority. The first non-overlapping frequencies may be all frequencies included in the first frequency band that do not overlap with the second frequency band, or may be all frequencies included in the first frequency band that do not overlap with the second frequency band. It may be some frequencies that do not overlap with the frequency band.

Specifically, UE 100 (control unit 130) regards the priority of frequency A as the lowest priority. On the other hand, UE 100 (control unit 130) maintains the priority of frequency B without regarding the priority of frequency B as the lowest priority.

(f) UE 100 (control unit 130) regards the priority of frequencies included in the second frequency band as higher priority than the priority of frequencies included in the first frequency band. The frequencies included in the second frequency band may be all frequencies included in the second frequency band, or may be some frequencies included in the second frequency band.

Specifically, UE 100 (control unit 130) regards the priority of frequency C as a higher priority than the priority of frequency A. The UE 100 (control unit 130) may consider the priority of frequency B to be higher than the priority of frequency A.

When multiple frequencies are included in the first frequency band, UE 100 (control unit 130) sets the priority of the frequency included in the second frequency band to the highest among the priorities of the multiple frequencies included in the first frequency band. It may be considered a higher priority than a higher priority.

(g) UE 100 (control unit 130) sets the priority of the frequency included in the second frequency band to a frequency that does not overlap with the second frequency band among the frequencies included in the first frequency band (that is, the first non- duplicate frequencies). The frequencies included in the second frequency band may be all frequencies included in the second frequency band, or may be some frequencies included in the second frequency band.

Specifically, the UE 100 (the control unit 130) regards the priority of the frequency C as higher priority than the priority of the frequency A, for example. UE 100 (control unit 130) may regard the priority of frequency B as a higher priority than the priority of frequency A, for example.

(h) UE 100 (control unit 130) regards the priority of frequencies included in the second frequency band as the highest priority. The frequencies included in the second frequency band may be all frequencies included in the second frequency band, or may be some frequencies included in the second frequency band. Specifically, UE 100 (control unit 130) may regard the priority of frequency B as the highest priority.

(i) UE 100 (control unit 130) regards cells belonging to the first frequency as prohibited cells that are prohibited from being selected as camp-on cells. A list of forbidden cells may be referred to as a blacklist. Specifically, UE 100 (control unit 130) regards cells belonging to frequency A as prohibited cells. UE 100 (control unit 130) may regard cells belonging to frequency B as prohibited cells.

(j) UE 100 (control unit 130) regards cells belonging to frequencies included in the first frequency band that do not overlap with the second frequency band (that is, first non-overlapping frequencies) as prohibited cells. Specifically, UE 100 (control unit 130) regards cells belonging to frequency A as prohibited cells.

UE 100 (control unit 130) performs normal cell selection operation or cell reselection operation after performing the above-described priority control. UE 100 (control unit 130), for example, makes the priority of frequencies included in the first frequency band relatively lower than the priority of frequencies included in the second frequency band by priority control. This makes it easier for UE 100 (control unit 130) to preferentially select cells belonging to the second frequency band over cells belonging to the first frequency band.

Step S203:
UE 100 (control unit 130) performs normal cell selection operation or cell reselection operation.

[Other embodiments]
In the operation of the above embodiment, the first network 200A and base station 210A may be read as cell C1 (first cell), and the first network 200A and base station 210A may be read as cell C2 (second cell). good too.

In the operation of the above embodiment, the number of receivers 121 may be three or more. Also, the number of transmission units 122 may be one, or may be three or more.

In the operation of the above embodiments, "frequency" may be replaced with "frequency band." The first frequency band may indicate the frequency range supported by the first receiving unit 121A, that is, the range of frequencies in which radio signals are received by the first receiving unit 121A. It may indicate the frequency range supported by the receiver 121B, that is, the frequency range in which the second receiver 121B receives radio signals. Each of the first frequency band (ie, the frequency range supported by the first receiving unit 121A) and the second frequency band (ie, the frequency range supported by the second receiving unit 121B) may be configured by one frequency band. It may well consist of multiple frequency bands.

In operation of the embodiments described above, the first frequency band and the second frequency band may not overlap. That is, the first frequency band and the second frequency band may be separated on the frequency axis. For example, the first receiver 121A supports reception of radio signals in one of frequency ranges FR1 (Frequency Range 1) and FR2 (Frequency Range 2), and the second receiver 121B supports the other frequency domain. radio signal reception. FR1 is the frequency band in the range 450-6000 Mhz. FR2 is the frequency band in the range 24250-52600 MHz.

In the operations of the above-described embodiments, an offset value may be added to communication quality as priority control. For example, the UE 100 (control unit 130) adds a negative offset value to the communication quality (eg, received power, received quality) measured in the frequency included in the first frequency band, and is compared with the reference in the selection operation. communication quality may be degraded. Also, the UE 100 (control unit 130) adds a positive offset value to the communication quality measured in the frequency included in the second frequency band, thereby increasing the communication quality compared with the reference in the selection operation.

In the operation of the above-described embodiment, the UE 100 (control unit 130) determines that the first receiving unit 121A is used for communication with the first network 200A when in the RRC connected state, and the RRC idle state Alternatively, it may be determined that the first receiver 121A is not used for communication with the first network 200A when it is in the RRC inactive state.

The steps in the operation of the above-described embodiments do not necessarily have to be performed in chronological order in the order depicted in the flow diagrams or sequence diagrams. For example, the steps in the operations may be performed out of order or in parallel with the order illustrated in the flow diagrams or sequence diagrams. Also, some steps in the operation may be omitted and additional steps may be added to the process. Furthermore, each operation flow described above is not limited to being implemented independently, but can be implemented 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.

A program that causes a computer to execute each process performed by the UE 100 or the base station 210 may be provided. The program may be recorded on a computer readable medium. A computer readable medium allows the installation of the program on the computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, but may be, for example, a recording medium such as CD-ROM or DVD-ROM. Alternatively, circuits for executing each process performed by the UE 100 or the base station 210 may be integrated, and at least part of the UE 100 or the base station 210 may be configured as a semiconductor integrated circuit (chipset, SoC).

It should be noted that in the above embodiments, "transmit" may mean performing processing of at least one layer in the protocol stack used for transmission, or transmitting signals wirelessly or by wire. It may mean physically transmitting. Alternatively, "transmitting" may mean a combination of performing the at least one layer of processing and physically transmitting the signal wirelessly or by wire. Similarly, "receive" may mean performing processing of at least one layer in the protocol stack used for reception, or physically receiving a signal wirelessly or by wire. may mean that Alternatively, "receiving" may mean a combination of performing the at least one layer of processing and physically receiving the signal wirelessly or by wire.

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

1: mobile communication system 100: UE
101: Antenna 102: Antenna 120: Communication unit 120A: First communication unit 120B: Second communication unit 121: Reception unit 121A: First reception unit 121B: Second reception unit 122: Transmission unit 122A: First transmission unit 122B: Second transmission unit 130 : control unit 200A : first network 200B : second network 210 : base station 210A : base station 210B : base station 211 : antenna 212 : communication unit 212a : reception unit 212b : transmission unit 213 : network interface 214 : Control unit 220A : Core network 220B : Core network 221 : Mobility management device 221A : Mobility management device 221B : Mobility management device 222 : Gateway device 222A : Gateway device 222B : Gateway device

Claims (10)

A user equipment (100) communicating with multiple networks (200A, 200B) using multiple subscriber identity modules (111, 112), comprising:
a first receiver (120A) that receives a radio signal in the first frequency band;
a second receiver (120B) that receives a radio signal in a second frequency band;
When the first receiver (120A) is used for communication with a first network (200A) included in the plurality of networks (200A, 200B), the first network included in the plurality of networks (200A, 200B) In the selection operation of selecting a camp-on cell in which the user equipment (100) is located in the second network (200B), the cell belonging to the second frequency band is preferentially selected over the cell belonging to the first frequency band. A user device comprising a control unit (130) that performs priority control. The control unit (130) sets the priority of frequencies included in the first frequency band to be lower than the priority of frequencies included in the second frequency band as the priority of frequencies in the selection operation. The user device according to claim 1, wherein the priority control is performed so as to The control unit (130) performs the priority control so that the priority of the frequency included in the first frequency band is regarded as the lowest priority as the priority of the frequency in the selection operation. 3. The user device according to claim 2. The control unit (130) determines the priority of the frequency used for communication with the first network (200A) among the frequencies included in the first frequency band as the priority of the frequency in the selection operation. 4. The user device according to claim 3, wherein the priority control is performed so as to regard as the lowest priority. The control unit (130) sets, as the priority of the frequency in the selection operation, the priority of a frequency that does not overlap with the second frequency band among the frequencies included in the first frequency band as the lowest priority. The user device according to claim 3 or 4, wherein the priority control is performed so as to The control unit (130) sets the priority of frequencies included in the second frequency band to be higher than the priority of frequencies included in the first frequency band as the priority of frequencies in the selection operation. The user device according to any one of claims 1 to 5, wherein the priority control is performed so as to assume The control unit (130) sets the priority of the frequency included in the second frequency band as the priority of the frequency in the selection operation to overlap with the second frequency band among the frequencies included in the first frequency band. The user apparatus according to any one of Claims 1 to 5, wherein the priority control is performed so as to regard the frequency as being higher in priority than the frequency not being used. 8. The control unit (130) performs the priority control so as to regard the priority of the frequency included in the second frequency band as the highest priority as the priority of the frequency in the selection operation. 2. User equipment according to claim 1. The control unit (130) performs the priority control so that a cell belonging to the frequency used for communication with the first network (200A) is regarded as a prohibited cell prohibited from being selected as the camp-on cell. The user equipment according to any one of claims 1 to 8. A communication control method executed by a user device (100) communicating with a plurality of networks (200A, 200B) using a plurality of subscriber identification modules (111, 112),
a step in which a first receiver (120A) of the user equipment (100) receives a radio signal in a first frequency band;
a step in which a second receiver (120B) of the user equipment (100) receives a radio signal in a second frequency band;
When the first receiver (120A) is used for communication with a first network (200A) included in the plurality of networks (200A, 200B), the first network included in the plurality of networks (200A, 200B) In the selection operation of selecting a camp-on cell in which the user equipment (100) is located in the second network (200B), the cell belonging to the second frequency band is preferentially selected over the cell belonging to the first frequency band. A communication control method, comprising: performing priority control.

Images