JP7400363B2 - Communication terminal, base station, and communication method - Google Patents

Description

The present disclosure relates to a communication terminal, a base station, and a communication method.

Companies, factories, etc., are implementing 5G wireless communication systems that operate using frequencies that require a license (licensed spectrum or licensed frequency) or frequencies that do not require a license (unlicensed spectrum or unlicensed frequency). Application to private networks is being considered. A private network to which a 5G wireless communication system is applied may be referred to as 5G-LAN, Private 5G, Vertical 5G, local 5G, or the like.

In factories that use cutting-edge technology, in order to control precision machines, synchronized communication with a frequency of several milliseconds is required between a control server and the precision machines. Furthermore, precision machinery may be mounted on vehicles that move within a factory. For precision machinery that requires mobility control, wireless access systems specified by the 3rd Generation Partnership Project (3GPP), which have better mobility characteristics than commonly used wireless LANs, and core networks that accommodate the wireless access systems are used. is desired to be applied. The 5G-LAN also uses a radio access system defined by the 3GPP and a core network that accommodates the radio access system. Non-Patent Document 1 discloses the configuration of a communication system that supports URLLC (Ultra-Reliable and Low Latency Communication) that realizes highly reliable and low-latency communication.

3GPP TR 23.725 V16.2.0 (2019-06)

In a communication system that supports URLLC, it is necessary to realize highly reliable and low-latency communication. Therefore, there is a need to reduce the burden on communication terminals subject to mobility control, base stations, etc. that execute mobility control within a communication system, and to realize communication with high reliability and low delay.

An object of the present disclosure is to provide a communication terminal, a base station, and a communication method that can reduce the burden on communication terminals that are subject to mobility control and base stations that execute mobility control within a communication system. .

A communication terminal according to a first aspect of the present disclosure includes a control unit that constructs a wireless channel with a base station, and a handover including identification information of the destination cell at a timing of handover to the destination cell. a communication unit that transmits a request message to the base station, and the timing of handover to the destination cell is determined based on a travel schedule to the destination.

A base station according to a second aspect of the present disclosure includes a control unit that constructs a wireless channel with a communication terminal, and an identification information of the destination cell at a timing when the communication terminal hands over to the destination cell. a communication unit that receives a message requesting handover from the communication terminal, and the timing of handover to the destination cell is determined based on a travel schedule of the communication terminal to the destination.

A communication method executed in a communication terminal according to a third aspect of the present disclosure establishes a wireless channel with a base station, and transmits identification information of the destination cell at the timing of handover to the destination cell. The communication terminal transmits a message requesting handover to the base station, and the timing of handover to the destination cell is determined based on a travel schedule to the destination.

A communication method executed in a base station according to a fourth aspect of the present disclosure includes establishing a wireless channel with a communication terminal, and transmitting information to the destination cell at a timing when the communication terminal hands over to the destination cell. A base station receives a message requesting a handover including identification information from the communication terminal, and the timing of handover to the destination cell is determined based on a movement schedule of the communication terminal to the destination. .

According to the present disclosure, it is possible to provide a communication terminal, a base station, and a communication method that can reduce the burden on a communication terminal subject to mobility control and a base station that executes mobility control within a communication system.

1 is a configuration diagram of a communication terminal according to Embodiment 1. FIG. FIG. 2 is a configuration diagram of a base station according to a second embodiment. FIG. 7 is a diagram showing the flow of PDU Connection setting processing according to the second embodiment. 7 is a diagram showing the flow of handover processing according to Embodiment 2. FIG. FIG. 7 is a diagram showing the flow of handover processing according to Embodiment 3; FIG. 2 is a configuration diagram of a relay device and a UE according to each embodiment. FIG. 2 is a configuration diagram of a base station according to each embodiment.

(Embodiment 1)
Embodiments of the present disclosure will be described below with reference to the drawings. A configuration example of the communication terminal 10 according to the first embodiment will be described using FIG. 1. The communication terminal 10 may be a computer device that operates by a processor executing a program stored in a memory. The communication terminal 10 may be a mobile phone terminal, a smartphone terminal, an IoT (Internet Of Things) terminal, an MTC (Machine Type Communication) terminal, or the like. Furthermore, the communication terminal 10 may be UE (User Equipment), which is used as a general term for communication terminals in 3GPP. Furthermore, the communication terminal 10 may be mounted on a vehicle or the like and moved. The vehicle may be, for example, an AGV (Automatic Guided Vehicle).

The communication terminal 10 has a control section 11 and a communication section 12. The control unit 11 and the communication unit 12 may be software or modules whose processing is executed by a processor executing a program stored in a memory. Alternatively, the control section 11 and the communication section 12 may be hardware such as a circuit or a chip.

The control unit 11 establishes a wireless channel with the base station 20. Specifically, the control unit 11 establishes a wireless channel with the base station 20 via the communication unit 12. The wireless channel may be called a Radio Resource Control (RRC) Connection, a Protocol Data Unit (PDU) Session, or the like.

The communication unit 12 transmits a message requesting a handover, including identification information of the destination cell, to the base station 20 at the timing when the communication terminal 10 is to handover to the destination cell. The destination cell may be referred to as a target cell. Handover is a process that is executed to continue communication when the communication terminal 10 moves from the current cell to the destination cell during communication.

The timing at which the communication terminal 10 hands over to the destination cell is determined based on the travel schedule of the communication terminal 10 to the destination. It is assumed that the travel schedule for the communication terminal 10 to the destination is determined in advance. The communication terminal 10 travels to a destination via a plurality of cells. That is, the communication terminal 10 repeatedly performs handover and moves to the destination. The movement schedule may include a movement route, a movement speed, a time to enter a cell area, a time to leave a cell area, a time to perform a handover, and the like. The communication terminal 10 may store a travel schedule to the destination in a memory within the communication terminal 10 or the like. An administrator or the like of the communication terminal 10 may input a travel schedule to the destination into the communication terminal 10. Alternatively, the communication terminal 10 may receive the travel schedule via a network from a server device or the like that stores the travel schedule.

Generally, a communication terminal executes a handover upon receiving an instruction message regarding execution of a handover from a base station. The base station transmits an instruction message to the communication terminal when the received power, reception quality, etc. of a message or signal transmitted from the communication terminal falls below a predetermined strength or quality. Upon receiving the instruction message, the communication terminal measures the reception power or reception quality of signals in surrounding cells, and transmits the measurement results to the base station. The base station determines the cell to which the communication terminal moves based on the measurement results transmitted from the communication terminal.

On the other hand, the timing at which communication terminal 10 according to the first embodiment executes handover is determined based on the movement schedule. For example, if the movement schedule determines the time when the communication terminal 10 will enter the area of the destination cell from the current cell, the timing at which the communication terminal 10 will execute handover is It may be the time when Alternatively, the timing at which the communication terminal 10 executes the handover may be a predetermined period before or after a predetermined period of time when the communication terminal 10 enters the area of the destination cell.

In this way, since the destination cell of communication terminal 10 is determined in advance, communication terminal 10 and base station 20 can omit the process of determining the destination cell. As a result, the processing by the communication terminal 10 and the base station 20 during handover is reduced compared to the case where the communication terminal measures the received power, etc. of neighboring cells.

(Embodiment 2)
Next, a configuration example of the communication system according to the second embodiment will be described using FIG. 2. In the communication system of FIG. 2, a configuration example of the base station 20 is shown. The configuration of the communication terminal 10 is the same as that of the communication terminal 10 in FIG. 1, so a detailed explanation will be omitted.

The base station 20 has a control section 21 and a communication section 22. Base station 20 may be a computer device whose processor operates by executing a program stored in memory. The base station 20 may be, for example, an eNB (evolved Node B) defined in 3GPP, an NR (New Radio) defined in 3GPP, or a so-called 5G defined in 3GPP. The base station may be a base station that supports a certain wireless communication standard.

The control unit 21 and the communication unit 22 may be software or modules whose processing is executed by a processor executing a program stored in a memory. Alternatively, the control section 21 and the communication section 22 may be hardware such as a circuit or a chip.

The control unit 21 establishes a wireless channel with the communication terminal 10. Specifically, the control unit 21 establishes a wireless channel with the communication terminal 10 via the communication unit 22. The communication unit 22 receives, from the communication terminal 10, a message requesting a handover, including identification information of the destination cell, at a time when the communication terminal 10 is to handover to the destination cell. The timing at which the communication terminal 10 hands over to the destination cell is determined based on the travel schedule of the communication terminal 10 to the destination.

Next, the flow of PDU (Protocol Data Unit) session setting processing according to the second embodiment will be described using FIG. 3. A PDU session may also be referred to as an RRC connection. Further, in FIG. 3, a UE 30 will be used as a device corresponding to the communication terminal 10 in FIG. 2. Further, in FIG. 3, an eNB 40 will be used as a device corresponding to the base station 20 in FIG. 2. In the explanation of FIG. 3 and subsequent figures, the explanation will be made using the UE and eNB, similarly to FIG. 3.

First, the UE 30 transmits a PRACH (Physical Random Access Channel) Preamble to the eNB 40 (S11). The PRACH Preamble is a signal first transmitted from the UE 30 when the UE 30 establishes or constructs a connection with the eNB 40 in the cell formed by the eNB 40. Next, the eNB 40 transmits a PRACH Response to the UE 30 (S12). The PRACH response includes information regarding the timing at which the UE 30 transmits the RRC Connection request. Next, the UE 30 transmits an RRC Connection request to the eNB 40 in order to establish an RRC Connection (S13). RRC Connection request includes Next handover information.

Next handover information is used to notify the eNB 40 of the movement schedule of the UE 30. Next handover information includes, for example, Target Cell ID, Carrier Frequency, and Expected Handover time. Target Cell ID is information that identifies the cell to which the UE 30 moves. In other words, the Target Cell ID is information that identifies the cell to which the UE 30 is to handover. The Target Cell ID is information that identifies not the cell where the UE 30 is currently located, but the cell after which the UE 30 moves from the cell where the UE 30 is currently located.

Carrier Frequency indicates the frequency used in the cell to which the UE 30 moves. Expected Handover time indicates the time when UE 30 executes handover. Alternatively, the Expected Handover time may be a time obtained by subtracting the current time from the time to perform handover. In other words, the expected handover time may be the time from the current time to the time when handover is executed.

Next, the eNB 40 transmits RRC Connection setup to the UE 30 (S14). RRC Connection setup includes control information for establishing RRC Connection between UE 30 and eNB 40. Next, the UE 30 transmits RRC Connection setup complete to the eNB 40 as a response to the RRC Connection setup (S15).

Although FIG. 3 shows an example in which the Next handover information is included in the RRC Connection request transmitted in step S13, it may also be included in the RRC Connection setup complete transmitted in step S15.

Further, the UE 30 may transmit UE Initiated Handover (UIH) UE support to the eNB 40 instead of Next handover information. UIH UE support is information indicating that the UE 30 is a UE that performs handover according to a predetermined movement schedule. Furthermore, the eNB 40 may transmit UIH RAN support to the UE 30. UIH RAN support is information indicating that the eNB 40 can support the operation or processing of a UE that performs handover according to a predetermined movement schedule. By transmitting UIH UE support and UIH RAN support between the UE 30 and the eNB 40, the UE 30 and the eNB 40 perform capability negotiation regarding the UIH function.

The UE 30 may include UIH UE support in the RRC Connection request or RRC Connection setup complete and transmit it. The eNB 40 may include UIH RAN support in the PRACH Response or RRC Connection setup and transmit it.

By executing the PDU Connection setting process shown in FIG. 3, the eNB 40 can receive Next handover information or UIH UE support. From this, the eNB 40 can recognize that the UE 30 is a UE that performs handover according to a predetermined movement schedule.

Next, the flow of handover processing according to the second embodiment will be described using FIG. 4. In FIG. 4, it is assumed that the process of FIG. 3 has been implemented, a PDU Session has been established between the UE 30 and the eNB 40, and the UE 30 and the eNB 40 are in communication (S21). Even while communicating with eNB 40, UE 30 is moving according to a predetermined movement schedule. Therefore, when the predetermined handover execution time is reached, the UE 30 determines to handover to a cell different from the cell formed by the eNB 40 (S22). Specifically, the UE 30 decides to handover to the cell formed by the eNB 41.

The UE 30 may decide to perform a handover, for example, when the UE 30 reaches a predetermined location or area, even when the handover execution time has not been reached. For example, when the UE 30 invades the cell area formed by the eNB 41, or before entering the cell area formed by the eNB 41, the UE 30 is located at a predetermined distance away from the boundary of the cell formed by the eNB 41. , it may be decided to handover. Alternatively, the UE 30 may decide to handover when it reaches a predetermined position within the cell formed by the eNB 41.

Next, the UE 30 transmits a handover indication to the eNB 40 (S23). Handover indication includes information indicating the cell to which the UE 30 moves. The information indicating the cell to which the UE 30 moves may be, for example, a Target cell ID. Target Cell ID indicates the cell formed by the eNB 41. The UE 30 transmits a Handover indication to the eNB 40 in order to notify that it will handover to a predetermined cell. UE30 transmits a handover indication to request handover to the cell formed by eNB41.

Next, the eNB 40 transmits a handover request to the eNB 41 forming the cell to which the UE 30 moves (S24). The eNB 41 transmits a Handover request ack to the eNB 40 as a response to the Handover request (S25).

Next, the eNB 40 transmits RRC connection reconfiguration to the UE 30 (S26). RRC connection reconfiguration includes, for example, information regarding the security algorithm used in the eNB 41. UE30 transmits RRC connection reconfiguration complete to eNB40 as a response to RRC connection reconfiguration (S27). Next, the eNB 40 transmits SN status transfer to the eNB 41 (S28). The SN status transfer includes, for example, a PDCP (Packet Data Convergence Protocol) SN (Sequence Number) indicating uplink data transmitted from the UE 30 to the eNB 40, and a PDCP SN indicating downlink data transmitted from the eNB 40 to the UE 30. But that's fine.

As described above, UE 30 according to the second embodiment can transmit a Handover indication to eNB 40 without receiving an instruction message regarding handover execution from eNB 40. From this, the UE 30 can omit the process of measuring the received power, received quality, etc. of signals in neighboring cells of the cell in which it is currently located. In other words, the processing load associated with measurement processing in the UE 30 is reduced. Furthermore, the eNB 40 has a reduced processing load associated with transmitting an instruction to execute the measurement process to the UE 30.

Furthermore, the handover indication in step S23 may be transmitted using a new RRC message that is not currently defined. Alternatively, Handover Indication may be transmitted using a measurement report, which is an existing message used to notify the eNB 40 of the result of measurement processing. For example, information indicating the destination cell included in the handover indication may be included in the measurement report as information identifying the cell where the measurement was performed. Further, instead of information indicating a measured value such as received power or received quality, information indicating that the UE 30 executes handover according to a predetermined movement schedule may be included in the measurement report.

(Embodiment 3)
Next, the flow of handover processing according to the third embodiment will be described using FIG. 5. Step S31 in FIG. 5 is similar to step S21 in FIG. 4, so detailed explanation will be omitted. Assume that Next handover information is transmitted from the UE 30 to the eNB 40 in step S31. As a result, it is assumed that the eNB 40 recognizes the movement schedule of the UE 30.

The eNB 40 determines the execution of Measurement in the UE 30 according to the Next handover information (S32). For example, the eNB 40 may decide to have the UE 30 perform Measurement at the time indicated in Expected Handover time. Alternatively, the eNB 40 may decide to cause the UE 30 to perform Measurement a predetermined time before the Expected Handover time, or after a predetermined time elapses from the Expected Handover time.

Next, the eNB 40 transmits RRC Connection reconfiguration to cause the UE 30 to perform Measurement (S33). RRC Connection reconfiguration includes messages or parameters that instruct measurement execution. For example, RRC Connection reconfiguration may include a message or parameter as a measurement request or measurement control. Here, the eNB 40 recognizes that the cell to which the UE 30 has moved is a cell formed by the eNB 41. Therefore, in the measurement request or measurement control, the eNB 40 sets only the Target Cell ID as information for identifying the cell that performs measurement. Specifically, the eNB 40 may set a Target Cell ID that identifies the cell formed by the eNB 41 in the measurement request or measurement control.

UE30 transmits RRC Connection reconfiguration complete to eNB40 as a response to RRC Connection reconfiguration (S34). Further, the UE 30 executes measurement to measure the received power, received quality, etc. of the signal in the cell identified by the Target Cell ID set in RRC Connection reconfiguration. The UE 30 transmits an RRC measurement report including the measurement execution result to the eNB 40 (S35). The RRC measurement report corresponds to a request message requesting handover to the Target Cell or an instruction message instructing handover to the Target Cell. Here, the UE 30 does not need to measure the received power, received quality, etc. of the signal in the cell identified by the Target Cell ID set in RRC Connection reconfiguration. In other words, since the cell to which the UE 30 will move next has been determined, the UE 30 does not need to perform measurement processing on the cell identified by the Target Cell ID. In this case, the UE 30 may set a predetermined value to the RRC Measurement report. The predetermined value may be, for example, a value of received power or received quality that allows the eNB 40 to permit handover to the cell formed by the eNB 41. Alternatively, the predetermined value may be a value indicating that the measurement process is omitted.

Steps S36 to S40 are similar to steps S24 to S28 in FIG. 4, so detailed explanation will be omitted.

Here, the UE 30 may include Next handover information indicating the movement schedule to the next cell formed by the eNB 41 in the RRC Connection reconfiguration complete transmitted in step S34. Furthermore, the eNB 40 may include Next handover information included in RRC Connection reconfiguration complete in the handover request transmitted in step S36. Alternatively, the UE 30 may include in RRC Connection reconfiguration complete Next handover information indicating a schedule for moving to multiple cells that may become future destinations.

In this way, when the eNB 41 receives the Next handover information indicating the movement schedule to the next cell of the cell formed by the eNB 41, the eNB 41 can decide to perform Measurement in the UE 30, as in step S32. can.

As described above, in the handover process of FIG. 5, the eNB 40 can specify the Target Cell ID included in the Next handover information as information for identifying the cell on which the UE 30 performs Measurement. This eliminates the need for the UE 30 to perform Measurement in cells other than the cell identified by the Target Cell ID. As a result, the processing load on the UE 30 when the Target Cell ID is specified is reduced compared to when the Target Cell ID is not specified.

Further, the eNB 41 can determine whether to perform Measurement in the UE 30 by receiving Next handover information indicating a movement schedule to the next cell.

Subsequently, configuration examples of the communication terminal 10 and the base station 20 described in the plurality of embodiments described above will be described below.

FIG. 6 is a block diagram showing a configuration example of the communication terminal 10. As shown in FIG. Radio Frequency (RF) transceiver 1101 performs analog RF signal processing to communicate with base station 20. Analog RF signal processing performed by RF transceiver 1101 includes frequency upconversion, frequency downconversion, and amplification. RF transceiver 1101 is coupled with antenna 1102 and baseband processor 1103. That is, RF transceiver 1101 receives modulation symbol data (or OFDM symbol data) from baseband processor 1103, generates a transmit RF signal, and supplies the transmit RF signal to antenna 1102. Further, RF transceiver 1101 generates a baseband reception signal based on the reception RF signal received by antenna 1102, and supplies this to baseband processor 1103.

The baseband processor 1103 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression/decompression, (b) data segmentation/concatenation, and (c) transmission format (transmission frame) generation/decomposition. Furthermore, digital baseband signal processing includes (d) channel encoding/decoding, (e) modulation (symbol mapping)/demodulation, and (f) OFDM symbol data (baseband OFDM including the generation of signals). Control plane processing, on the other hand, includes layer 1 (e.g., transmit power control), layer 2 (e.g., radio resource management, and hybrid automatic repeat request (HARQ) processing), and layer 3 (e.g., attach, mobility, and call management). including communication management (signaling related to communication).

For example, for LTE and 5G, digital baseband signal processing by baseband processor 1103 may include signal processing of a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a MAC layer, and a PHY layer. . Further, the control plane processing by the baseband processor 1103 may include processing of a Non-Access Stratum (NAS) protocol, an RRC protocol, and a MAC CE.

The baseband processor 1103 includes a modem processor (e.g., Digital Signal Processor (DSP)) that performs digital baseband signal processing, and a protocol stack processor (e.g., Central Processing Unit (CPU)) or Micro Processing Unit that performs control plane processing. (MPU)). In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1104, which will be described later.

Application processor 1104 is also referred to as a CPU, MPU, microprocessor, or processor core. Application processor 1104 may include multiple processors (multiple processor cores). The application processor 1104 implements various functions of the communication terminal 10 by executing a system software program (Operating System (OS)) and various application programs read from the memory 1106 or a memory not shown. The application program may be, for example, a telephone call application, a web browser, a mailer, a camera operation application, or a music playback application.

In some implementations, baseband processor 1103 and application processor 1104 may be integrated on one chip, as shown in dashed line (1105) in FIG. In other words, the baseband processor 1103 and the application processor 1104 may be implemented as one System on Chip (SoC) device 1105. An SoC device is sometimes called a system Large Scale Integration (LSI) or chipset.

Memory 1106 is volatile memory or non-volatile memory or a combination thereof. Memory 1106 may include multiple physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM) or a combination thereof. Non-volatile memory is masked Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. For example, memory 1106 may include external memory devices accessible from baseband processor 1103, application processor 1104, and SoC 1105. Memory 1106 may include embedded memory devices integrated within baseband processor 1103, within application processor 1104, or within SoC 1105. Additionally, memory 1106 may include memory within a Universal Integrated Circuit Card (UICC).

The memory 1106 may store a software module (computer program) including a group of instructions and data for performing processing by the communication terminal 10 described in the multiple embodiments described above. In some implementations, the baseband processor 1103 or the application processor 1104 may be configured to read and execute the software module from the memory 1106 to perform the processing of the communication terminal 10 described in the embodiments above. good.

FIG. 7 is a block diagram showing an example of the configuration of the base station 20. As shown in FIG. Referring to FIG. 7, base station 20 includes an RF transceiver 1001, a network interface 1003, a processor 1004, and a memory 1005. RF transceiver 1001 performs analog RF signal processing to communicate with UEs. RF transceiver 1001 may include multiple transceivers. RF transceiver 1001 is coupled to antenna 1002 and processor 1004. RF transceiver 1001 receives modulation symbol data (or OFDM symbol data) from processor 1004, generates a transmit RF signal, and provides the transmit RF signal to antenna 1002. Further, RF transceiver 1001 generates a baseband reception signal based on the reception RF signal received by antenna 1002 and supplies this to processor 1004.

Network interface 1003 is used to communicate with network nodes (e.g. other core network nodes). Network interface 1003 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

Processor 1004 performs data plane processing and control plane processing including digital baseband signal processing for wireless communications. For example, for LTE and 5G, digital baseband signal processing by processor 1004 may include MAC layer and PHY layer signal processing.

Processor 1004 may include multiple processors. For example, processor 1004 may include a modem processor (e.g., DSP) that performs digital baseband signal processing and a protocol stack processor (e.g., CPU or MPU) that performs control plane processing.

Memory 1005 is configured by a combination of volatile memory and nonvolatile memory. Memory 1005 may include multiple physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM) or a combination thereof. Non-volatile memory is masked Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. Memory 1005 may include storage located remotely from processor 1004. In this case, processor 1004 may access memory 1005 via network interface 1003 or an I/O interface (not shown).

Memory 1005 may store software modules (computer programs) that include instructions and data for processing by base station 20 as described in the embodiments above. In some implementations, processor 1004 may be configured to retrieve and execute the software modules from memory 1005 to perform the operations of base station 20 described in the embodiments above.

In the examples above, the program may be stored and provided to the computer using various types of non-transitory computer readable media. Non-transitory computer-readable media includes various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media, magneto-optical recording media (e.g. magneto-optical disks), CD-ROM (Read Only Memory), CD-R, CD-R/W, semiconductor memory, and flash ROM. , RAM (Random Access Memory)). The magnetic recording medium may be, for example, a flexible disk, magnetic tape, or hard disk drive. The semiconductor memory may be, for example, a mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, or RAM (Random Access Memory). The program may also be provided to the computer on various types of transitory computer readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can provide the program to the computer via wired communication channels, such as electrical wires and fiber optics, or wireless communication channels.

Note that the present disclosure is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit.

Part or all of the above embodiments may be described as in the following additional notes, but are not limited to the following.
(Additional note 1)
a control unit that establishes a wireless channel with the base station;
a communication unit that transmits a handover request message including identification information of the destination cell to the base station at the timing of handover to the destination cell;
The communication terminal wherein the timing of handover to the destination cell is determined based on a travel schedule to the destination.
(Additional note 2)
The control unit includes:
When constructing the wireless channel, transmitting identification information of the destination cell and timing information for handover to the destination cell to the base station,
The communication department includes:
The communication terminal according to supplementary note 1, wherein the communication terminal receives a message instructing handover from the base station at a timing of handover to the destination cell.
(Additional note 3)
The communication terminal according to appendix 2, wherein the message instructing the handover includes identification information of the destination cell.
(Additional note 4)
The communication terminal according to appendix 2 or 3, wherein the message instructing the handover includes only identification information of the destination cell as a cell to be searched by the communication terminal.
(Appendix 5)
The communication department includes:
Any one of appendices 1 to 4, wherein a message requesting the handover including identification information of a next destination cell of the destination cell and timing information for handover to the next destination cell is transmitted to the base station. The communication terminal according to item 1.
(Appendix 6)
The control unit includes:
determining the timing for handover to the destination cell based on the travel schedule to the destination;
The communication department includes:
6. The communication terminal according to any one of Supplementary Notes 1 to 5, which transmits a message requesting a handover including identification information of the destination cell to the base station at the determined timing.
(Appendix 7)
The control unit includes:
The communication terminal according to appendix 6, wherein the communication terminal transmits information indicating that the message requesting the handover will be transmitted at the timing determined by the communication terminal when establishing a wireless channel with the base station.
(Appendix 8)
a control unit that constructs a wireless channel with the communication terminal;
a communication unit that receives a message requesting a handover including identification information of the destination cell from the communication terminal at a timing when the communication terminal hands over to the destination cell;
The base station determines the timing of handover to the destination cell based on a travel schedule of the communication terminal to the destination.
(Appendix 9)
The control unit includes:
When constructing a wireless channel with a communication terminal, the communication terminal receives information regarding a handover timing to a destination cell;
The communication department includes:
The base station according to appendix 8, wherein the base station transmits an instruction message instructing execution of handover to the communication terminal at a timing when the communication terminal hands over to the destination cell.
(Appendix 10)
The communication department includes:
The base station according to appendix 8, wherein the base station transmits the instruction message including identification information of the destination cell to the communication terminal.
(Appendix 11)
Build a wireless channel with the base station,
transmitting a message requesting handover including identification information of the destination cell to the base station at the timing of handover to the destination cell;
A communication method executed in a communication terminal, wherein the timing of handover to the destination cell is determined based on a travel schedule to the destination.
(Appendix 12)
Build a wireless channel with the communication terminal,
receiving a message requesting a handover including identification information of the destination cell from the communication terminal at a timing when the communication terminal hands over to the destination cell;
A communication method executed at a base station, wherein the timing of handover to the destination cell is determined based on a movement schedule of the communication terminal to the destination.
(Appendix 13)
Build a wireless channel with the base station,
causing a computer to transmit a message requesting handover including identification information of the destination cell to the base station at the timing of handover to the destination cell;
The program determines the timing of handover to the destination cell based on a travel schedule to the destination.
(Appendix 14)
Build a wireless channel with the communication terminal,
causing a computer to receive a message requesting handover including identification information of the destination cell from the communication terminal at a timing when the communication terminal hands over to the destination cell;
The timing of handover to the destination cell is determined based on a travel schedule of the communication terminal to the destination.

10 communication terminal 11 control unit 12 communication unit 20 base station 21 control unit 22 communication unit 30 UE
40 eNB
41 eNB

Claims (6)

a control unit that establishes a wireless channel with the base station;
a communication unit that receives a message instructing handover from the base station at the timing of handover to a destination cell;
When constructing the wireless channel, the control unit transmits identification information of the destination cell and timing information for handover to the destination cell to the base station,
The communication terminal wherein the timing of handover to the destination cell is determined based on a travel schedule to the destination. The communication terminal according to claim 1 , wherein the message instructing the handover includes identification information of the destination cell. 3. The communication terminal according to claim 1 , wherein the message instructing the handover includes only identification information of the destination cell as a cell to be searched by the communication terminal. a control unit that constructs a wireless channel with the communication terminal;
a communication unit that transmits a message instructing handover at a timing when the communication terminal hands over to a destination cell;
The control unit receives identification information of the destination cell and timing information for handover to the destination cell from the communication terminal when constructing the wireless channel;
The base station determines the timing of handover to the destination cell based on a travel schedule of the communication terminal to the destination. Build a wireless channel with the base station,
receiving a message instructing handover from the base station at the timing of handover to the destination cell;
When constructing the wireless channel, transmitting identification information of the destination cell and timing information for handover to the destination cell to the base station,
A communication method executed in a communication terminal, wherein the timing of handover to the destination cell is determined based on a travel schedule to the destination. Build a wireless channel with the communication terminal,
transmitting a message instructing handover at a timing when the communication terminal hands over to a destination cell;
When constructing the radio channel, receiving identification information of the destination cell and timing information for handover to the destination cell from the communication terminal;
A communication method executed at a base station, wherein the timing of handover to the destination cell is determined based on a movement schedule of the communication terminal to the destination.

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