WO2013024574A1 - ハンドオーバ制御方法、無線通信端末及び無線通信装置 - Google Patents
ハンドオーバ制御方法、無線通信端末及び無線通信装置 Download PDFInfo
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- WO2013024574A1 WO2013024574A1 PCT/JP2012/004874 JP2012004874W WO2013024574A1 WO 2013024574 A1 WO2013024574 A1 WO 2013024574A1 JP 2012004874 W JP2012004874 W JP 2012004874W WO 2013024574 A1 WO2013024574 A1 WO 2013024574A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
- H04W36/0016—Hand-off preparation specially adapted for end-to-end data sessions
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0055—Transmission or use of information for re-establishing the radio link
- H04W36/0058—Transmission of hand-off measurement information, e.g. measurement reports
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0055—Transmission or use of information for re-establishing the radio link
- H04W36/0069—Transmission or use of information for re-establishing the radio link in case of dual connectivity, e.g. decoupled uplink/downlink
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0055—Transmission or use of information for re-establishing the radio link
- H04W36/0069—Transmission or use of information for re-establishing the radio link in case of dual connectivity, e.g. decoupled uplink/downlink
- H04W36/00692—Transmission or use of information for re-establishing the radio link in case of dual connectivity, e.g. decoupled uplink/downlink using simultaneous multiple data streams, e.g. cooperative multipoint [CoMP], carrier aggregation [CA] or multiple input multiple output [MIMO]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
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- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0055—Transmission or use of information for re-establishing the radio link
- H04W36/0079—Transmission or use of information for re-establishing the radio link in case of hand-off failure or rejection
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
- H04W36/302—Reselection being triggered by specific parameters by measured or perceived connection quality data due to low signal strength
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- H—ELECTRICITY
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- H04W36/304—Reselection being triggered by specific parameters by measured or perceived connection quality data due to measured or perceived resources with higher communication quality
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- H—ELECTRICITY
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- H04W36/249—Reselection being triggered by specific parameters according to timing information
Definitions
- the present disclosure relates to a handover control method, a wireless communication terminal, and a wireless communication device performed by a wireless communication terminal that communicates with one or a plurality of wireless communication devices using a control channel and a data channel.
- LTE-Advanced Long Term Evolution Advanced: LTE-A
- LTE-U Long Term Evolution Advanced
- NE Network Entity
- the wireless communication device is a wireless communication terminal (User Equipment: UE) such as a wireless communication base station (E-UTRAN NodeB: eNB), an extended base station (Remote Head: RRH), a relay device (relay node or repeater), etc. This is an access point device.
- the wireless communication terminal belongs to one communication cell among one or more communication cells provided by the wireless communication device. Note that, when a plurality of frequencies are used, the wireless communication terminal belongs to one communication cell at one frequency.
- the communication cell is simply referred to as “cell”, and the wireless communication terminal is simply referred to as “terminal”.
- an adjacent cell refers to any cell among all cells other than the own cell to which the terminal is connected. Note that even if a cell is not connected to a terminal, if the terminal is used for receiving a physical downlink shared channel (PDSCH), the cell is not included even if it is included in an adjacent cell. May be.
- PDSCH physical downlink shared channel
- E-UTRA Evolved Universal Terrestrial Radio Access
- RRC Radio Resource Control
- the purpose of the present disclosure is to ensure that even when the reception quality of the data channel signal in the own cell to which the wireless communication terminal is connected differs from the reception quality of the control channel signal, the wireless communication terminal is in an appropriate situation when the wireless communication terminal is moving.
- a radio communication terminal and a radio communication apparatus capable of performing handover to an adjacent cell.
- the present disclosure is a handover control method performed by a wireless communication terminal that communicates with a wireless communication apparatus using a control channel and a data channel, and is transmitted from the wireless communication apparatus that provides the own cell to which the wireless communication terminal is connected.
- a conditional handover command instructing to start a handover to an adjacent cell is received, it is determined whether the predetermined condition is satisfied, and if the predetermined condition is satisfied, Provided is a handover control method for starting a handover to the neighboring cell indicated by a conditional handover command.
- the present disclosure is a wireless communication terminal that communicates with a wireless communication apparatus using a control channel and a data channel, and a predetermined condition transmitted from the wireless communication apparatus that provides the own cell to which the wireless communication terminal is connected. If the condition is satisfied, a receiving unit that receives a conditional handover command instructing to start handover to an adjacent cell, a handover determining unit that determines whether or not the predetermined condition is satisfied, and if the predetermined condition is satisfied And a handover processing unit that starts a handover to the adjacent cell indicated by the conditional handover command.
- the present disclosure is a wireless communication apparatus that communicates with a wireless communication terminal using a control channel and a data channel and provides a local cell to which the wireless communication terminal is connected, and includes information transmitted from the wireless communication terminal or Based on the environment provided by the wireless communication device to the wireless communication terminal, the wireless communication terminal determines an adjacent cell to be handed over, and the handover performed by the wireless communication terminal is adjacent if a predetermined condition is satisfied.
- a conditional handover determination unit that selects either a conditional handover that starts a handover or a handover that does not require a condition, and starts a handover to the adjacent cell if a predetermined condition is satisfied
- a wireless transmission unit for transmitting a conditional handover command to the wireless communication terminal, and the wireless communication End is detects that the started handover, to provide a radio communication apparatus and a network transmission unit for transferring data of the wireless communication addressed to the terminal in a radio communication apparatus that provides the neighboring cell.
- the present disclosure is a wireless communication apparatus capable of communicating with a wireless communication terminal using a control channel and a data channel, and providing a cell adjacent to the own cell to which the wireless communication terminal is connected,
- a network receiving unit that receives a handover request message transmitted from a wireless communication apparatus that provides a conditional handover based on the handover request message and instructing to start handover to an adjacent cell if a predetermined condition is satisfied
- Wireless communication for providing the own cell with a command creation unit that creates either a command or a handover command that does not require a condition, and a handover response message that includes the conditional handover command or the handover command created by the command creation unit
- Network transmitter that transmits to the device ,
- the command generating unit when creating the conditional handover command, based environment provided to the wireless communication terminal, to provide a wireless communication device for determining the predetermined condition.
- the reception quality of the data channel signal in the own cell to which the radio communication terminal is connected is different from the reception quality of the control channel signal.
- FIG. 1 shows an example of the timing chart at the time of a terminal performing UE1 handover in the radio
- the block diagram of terminal UE1 which comprises the radio
- movement of terminal UE1 of 1st Embodiment when a predetermined condition is the condition 1.
- movement of terminal UE1 of 1st Embodiment when a predetermined condition is the condition 3.
- Block diagram of a radio communication device SNE1 constituting the radio communication system of the first embodiment 1 is a block diagram of a wireless communication device TNE constituting a wireless communication system according to a first embodiment.
- movement of terminal UE2 of 2nd Embodiment when a predetermined condition is the condition 1.
- Block diagram of a wireless communication device SNE2 constituting the wireless communication system of the second embodiment The figure which shows an example of the timing chart at the time of terminal UE3 performing a handover in the radio
- movement of terminal UE3 of 3rd Embodiment when a predetermined condition is the condition 1.
- wireless communication apparatus SNE3 which comprises the radio
- the figure which shows an example of the timing chart at the time of terminal UE4 performing a handover in the radio
- the block diagram of terminal UE4 which comprises the radio
- wireless communication apparatus SNE4 which comprises the radio
- FIG. 18 is a diagram illustrating an example of a timing at which a terminal performs handover from its own cell to an adjacent cell.
- the coverage of PDSCH reception quality of a cell provided by each wireless communication base station is equal to or higher than the coverage of PDCCH (Physical Downlink Control Channel) reception quality equal to or higher than a certain level. . Therefore, when a terminal connected to the cell of the radio communication base station eNB1 moves to the point A shown in FIG. 18, a handover to an adjacent cell provided by the radio communication base station eNB2 is performed.
- the point A is an intermediate point of the coverage of the reception quality of the PDCCH of the cell provided by each wireless communication base station.
- FIG. 19 is a diagram illustrating an example of timing when a terminal is handed over from its own cell to an adjacent cell when a terminal connected to the cell of the radio communication base station eNB1 is cooperatively transmitted from the extended base station (RRH). It is.
- the RRH illustrated in FIG. 19 is installed at a position away from the radio communication base station eNB1, and is connected to the radio communication base station eNB1 by an optical fiber cable or the like.
- the terminal receives PDSCH from both the radio communication base stations eNB1 and RRH. For this reason, the coverage of the reception quality of the PDSCH of the own cell received by the terminal is larger than the coverage of the reception quality of the PDCCH of the own cell.
- the PDSCH reception quality in the adjacent cell is higher than the PDSCH reception quality in the own cell, and the terminal throughput is higher. Can be maintained.
- the timing at which the radio communication base station eNB1 sends a handover command to the terminal is as shown in FIG. It will be slower than the case shown in.
- a wireless communication system includes at least one wireless communication terminal and a plurality of wireless communication devices that can communicate with the wireless communication terminal via a wireless communication network.
- the wireless communication terminal is simply referred to as “terminal”.
- the terminal is, for example, a mobile phone.
- a radio communication device is a radio communication base station (E-UTRAN NodeB: eNB), an overhang base station (Remote Radio Head: RRH) installed at a position away from the radio communication base station,
- E-UTRAN NodeB eNB
- RRH Remote Radio Head
- the overhang base station has the same function as the radio unit (Radio-Frequency unit: RF unit) of the radio communication base station (eNB), and is a radio communication base station (eNB) using a wired cable such as an optical fiber cable. )It is connected to the.
- RF unit Radio-Frequency unit
- eNB radio communication base station
- wired cable such as an optical fiber cable.
- the wireless communication system uses LTE or LTE-A mobile communication technology standardized by 3GPP (The 3rd Generation Generation Partnership Project).
- the mobile communication technology used by the wireless communication system is not limited to the above-mentioned standard, and is not limited to the wireless LAN (Wireless Local Area Network), IEEE802.16, IEEE802.16e, IEEE802.16m, etc., WiMAX (Worldwide Interoperability for Microwave Access), It may be 3GPP2, SAE (System Architecture Evolution), UMTS (Universal Mobile Telecommunications System), or the fourth generation mobile communication standard.
- Each wireless communication device constitutes at least one communication cell.
- a communication cell refers to a radio network object that a terminal can uniquely identify based on an identifier assigned to a geographical area or a difference in frequency used in the geographical area.
- a communication cell is simply referred to as a “cell”.
- One radio communication apparatus constitutes one or more cells for each of one or more carrier frequencies.
- the said structure is a basic concept and a radio
- the terminal communicates using at least one cell configured by the wireless communication device.
- Multi-point cooperation is a technique for improving the throughput of a terminal by a plurality of wireless communication apparatuses operating in cooperation.
- a plurality of wireless communication devices constitute separate cells, and a terminal is a cell (own cell) formed by one wireless communication device in a CoMP set (a group of wireless communication devices operating in cooperation with one terminal). Connect to.
- a plurality of wireless communication devices may constitute one cell.
- the terminal receives a physical downlink control channel (Physical Downlink Control Channel: PDCCH) from its own cell, and transmits a data packet addressed to the terminal transmitted in cooperation by each wireless communication device of the CoMP set to the physical downlink shared channel (Physical Downlink Shared (Channel: PDSCH). Accordingly, the coverage of PDSCH reception quality in the own cell is greater than a certain level, and the coverage of PDCCH reception quality is greater than the certain level.
- PDCCH Physical Downlink Control Channel
- PDSCH Physical Downlink Shared
- the wireless communication system according to the first embodiment includes the terminal and the wireless communication device described above.
- the terminal receives a reference signal transmitted from the wireless communication apparatus for each cell in the downlink, and reports a measurement result derived based on a predetermined calculation formula to the wireless communication apparatus.
- the radio communication apparatus assigns and manages radio resources (for example, a frequency band in a frequency domain or a time domain) to each terminal, and serves as an access point of a radio access network for the terminal.
- the wireless communication apparatus has a function of performing a handover process when it is determined that a handover to another cell is necessary based on a measurement result report from the terminal.
- FIG. 1 is a diagram illustrating an example of a timing chart when the terminal UE1 performs a handover in the wireless communication system according to the first embodiment.
- a radio communication apparatus Source Network Entity
- SNE1 that provides a cell (Serving Cell, hereinafter referred to as “own cell”) to which the terminal UE1 is connected is transmitted from the terminal UE1 to a measurement result report (Measurement Report). Etc., and execution of conditional handover and its handover destination are determined.
- the radio communication device SNE1 transmits a handover request message to the handover destination radio communication device (Target Network Entity) TNE.
- the radio communication device TNE performs a handover approval process.
- the radio communication device TNE transmits a handover response message including a conditional handover command to the radio communication device SNE1.
- the wireless communication device SNE1 that has received the handover response message transmits a conditional handover command to the terminal UE1.
- the conditional handover command includes a predetermined condition necessary for the terminal UE1 to determine the timing for starting the handover.
- the terminal UE1 When the terminal UE1 receives the conditional handover command, the terminal UE1 continuously monitors whether or not a predetermined condition described later is satisfied. And terminal UE1 does not start a handover until predetermined conditions are satisfied, but continues communication with radio
- the wireless communication device SNE1 When the wireless communication device SNE1 detects that the terminal UE1 has started handover by some method, the wireless communication device SNE1 starts to transfer the data addressed to the terminal UE1 to the wireless communication device TNE and start transmitting data addressed to the terminal UE1 (Sequence Number ) And the notification of the sequence number for receiving data from the terminal UE1.
- the wireless communication device SNE1 starts data transfer to the wireless communication device TNE before detecting the handover of the terminal UE1, and transmits data addressed to the terminal UE1 when detecting that the terminal UE1 has started handover.
- the wireless communication device TNE may be notified of the sequence number (Sequence Number) for starting the transmission and the sequence number for receiving data from the terminal UE1. In this way, the terminal UE1 can receive data from the radio communication device TNE immediately after the handover. Further, since the radio communication apparatus TNE can recognize which data should be transmitted to the terminal UE1, it is not necessary to transmit data already received by the terminal to the terminal.
- the terminal UE1 that has started the handover first sends a random access preamble (Random Access Preamble) as an uplink synchronization establishment request to the radio communication device TNE indicated by the conditional handover command.
- a random access preamble Random Access Preamble
- the terminal UE1 transmits a handover complete message (Handover ⁇ Complete) to the radio communication device TNE.
- the terminal UE1 performs a handover from its own cell provided by the radio communication device SNE1 to an adjacent cell provided by the radio communication device TNE.
- the predetermined condition may be a condition different from the conditions 1 to 11 within a range that satisfies the object of the present disclosure.
- the wireless communication device TNE that has received the handover request message sets a predetermined condition. Note that the timing at which the terminal UE1 starts handover varies depending on which of the conditions 1 to 11 is set as the predetermined condition.
- Condition 1 is that the PDSCH reception quality in the handover destination cell (adjacent cell) indicated by the conditional handover command measured by the terminal is better than the PDSCH reception quality in the own cell.
- the terminal When setting condition 1, for example, the terminal derives the PDSCH reception quality of the handover destination cell based on RSRP measured using a cell reference signal (Cell-Specific Reference Symbol: CRS), for example. Further, the terminal may calculate the PDSCH reception quality of the handover destination cell by adding the offset value to the measurement result measured using the CRS on the assumption that the conditional handover command includes the offset value. Good. Since reception quality measurement using CRS has been performed conventionally, it is not necessary to greatly change the terminal specifications in order to obtain the PDSCH reception quality of the handover destination cell.
- CRS Cell-Specific Reference Symbol
- the terminal may measure the reception quality of the currently used PDSCH as the PDSCH of its own cell using CSI-RS (CSI Reference Signals) in the PDSCH region. Note that the terminal measures only the reception quality of the currently used PDSCH using CSI-RS, and derives the PDSCH reception quality of the handover destination cell using the above-described measurement results using CRS. Also good.
- CSI-RS CSI Reference Signals
- the terminal may measure the reception quality of the PDSCH currently used as the PDSCH of the own cell using DMRS (Demodulation Reference Signals) in the PDSCH region.
- DMRS Demodulation Reference Signals
- the terminal may measure only the reception quality of the currently used PDSCH using DMRS, and derive the PDSCH reception quality of the handover destination cell using the measurement result using CRS described above.
- any method may be used as the PDSCH measurement method regardless of the above method.
- Condition 2 is that the reception quality measured by the terminal of the PDCCH of the cell (own cell) to which the terminal is currently connected is lower than the threshold. If condition 2 is set as a handover start condition, handover is started immediately after the terminal cannot receive data from the own cell or immediately before the terminal cannot receive data from the own cell. For this reason, the non-communication period during which the terminal cannot receive data can be minimized.
- the threshold to be compared with the reception quality of the PDCCH of the own cell is included in the conditional handover command.
- the threshold value may be a value at which the PDCCH of the own cell cannot be received.
- the terminal may hold the threshold value.
- the conditional handover command may notify the terminal held by the terminal to use as a threshold a value at which the terminal cannot receive the PDCCH of the own cell.
- Condition 3 is to satisfy Condition 1 or Condition 2.
- Condition 3 By setting Condition 3 as a handover start condition, it is possible to minimize the no-communication period while considering the reception quality of PDSCH.
- Condition 4 is that the elapsed time from reception of the conditional handover command reaches the “handover start limit time”.
- the terminal starts handover immediately before the condition 4 is satisfied.
- condition 4 As a handover start condition, it is possible to limit the time that the handover destination wireless communication apparatus waits for a terminal to be handed over. Note that if the delay from the time when the terminal starts handover to the time when the terminal actually hands over to the adjacent cell is taken into account by the handover destination wireless communication apparatus, the terminal may start handover after satisfying condition 4 . In this case, it is possible to minimize the period for reserving resources for the terminal to be handed over in the handover destination wireless communication apparatus.
- Condition 5 is not a condition for starting handover, but is a condition for canceling conditional handover processing.
- Condition 5 is that the elapsed time from reception of the conditional handover command reaches the “conditional handover cancellation time”.
- the terminal stops the conditional handover process.
- condition 5 as a condition for canceling conditional handover, it is possible to limit the time that the handover destination wireless communication apparatus waits for a terminal to be handed over. Further, the terminal may stop the conditional handover process immediately before the condition 5 is satisfied. In this case, it is possible to minimize the period for reserving resources for the terminal to be handed over in the handover destination wireless communication apparatus.
- Condition 6 is to satisfy Condition 1 or Condition 4.
- Condition 7 is that Condition 1 is satisfied before Condition 5 is satisfied. If the condition 5 is satisfied before the condition 1 is satisfied, the terminal stops the conditional handover process.
- Condition 8 is to satisfy Condition 2 or Condition 4.
- Condition 9 is to satisfy condition 2 before condition 5 is satisfied. If the condition 5 is satisfied before the condition 2 is satisfied, the terminal stops the conditional handover process.
- Condition 10 is to satisfy condition 3 or condition 4. In other words, the condition 10 is to satisfy the condition 1, the condition 2 or the condition 4.
- Condition 11 is that Condition 3 is satisfied before Condition 5 is satisfied. If the condition 5 is satisfied before the condition 3 is satisfied, the terminal stops the conditional handover process.
- the condition 12 is not a condition for starting a handover, but a condition for stopping the conditional handover process.
- the reception quality measured by the terminal of the PDCCH of the own cell is higher than the threshold value.
- the condition 13 is not a condition for starting a handover, but a condition for stopping the conditional handover process.
- the reception quality measured by the terminal of the PDCCH of the own cell is high in the reception quality measured by the terminal of the PDCCH of the handover destination. Note that the reception quality may be determined by adding an offset.
- the condition 14 is not a condition for starting the handover, but a condition for stopping the conditional handover process.
- the reception quality measured by the terminal of the PDSCH of its own cell is high in the reception quality measured by the terminal of the handover destination PDCCH.
- the terminal UE1 and the wireless communication device TNE may have a timer for holding individual resources of a random access preamble (Random Access Preamble).
- the radio communication apparatus TNE includes a value of a timer (individual RACH holding timer) that holds the dedicated resource of the random access preamble in the conditional handover command.
- the terminal UE1 receives the conditional handover command including the value of the dedicated RACH holding timer, the terminal UE1 starts counting by the dedicated RACH holding timer. While the dedicated RACH holding timer is counting, the terminal UE1 transmits a random access preamble using dedicated resources during handover.
- the terminal UE1 determines that the dedicated resource of the random access preamble cannot be used, and contention-based random access (Random Start Access (Procedure). In this way, it is possible to limit the number of random access preamble individual resources consumed by the network for one terminal.
- the terminal may always start the dedicated RACH holding timer. Further, when the value of the dedicated RACH holding timer is included in the conditional handover command, the value of the dedicated RACH holding timer held by the terminal itself may be updated. A flag indicating whether or not to use the dedicated RACH holding timer may be included in the conditional handover command.
- FIG. 2 is a block diagram of the terminal UE1 configuring the wireless communication system according to the first embodiment.
- the terminal UE1 of the first embodiment includes a reception unit 101, a control unit 103, and a transmission unit 105.
- the control unit 103 includes a measurement unit 111, a handover determination unit 113, a handover information holding unit 115, and a handover processing unit 117.
- the terminal UE1 has a timer (not shown) that counts an elapsed time from reception of the conditional handover command. The timer expires when counting the time set by the conditional handover command.
- the receiving unit 101 receives control information such as broadcast information or individual control information via the downlink of the cell to which the terminal UE1 is connected in response to an instruction from the control unit 103.
- the receiving unit 101 outputs the received notification information, individual control information, and the like to the control unit 103.
- the receiving unit 101 receives a reference signal (for example, a cell reference signal (CRS) Signal: CRS) or receives a received signal strength (Received Signal Signal Strength: RSSI) in response to an instruction from the measurement unit 111 of the control unit 103. ).
- the receiving unit 101 outputs a measurement result such as the received reference signal or RSSI to the measuring unit 111.
- the receiving unit 101 receives a random access response (Random Access Response) or the like from the handover destination cell, and outputs it to the control unit 103.
- Random Access Response Random Access Response
- the control unit 103 instructs the receiving unit 101 to receive notification information or individual control information.
- Control information such as broadcast information or individual control information received by the receiving unit 101 is input to the control unit 103.
- the control unit 103 determines whether a conditional handover command is included in the input control information.
- control information including a conditional handover command is input, the control unit 103 outputs the predetermined condition included in the conditional handover command to the handover determination unit 113. Further, the control unit 103 stores information necessary for the handover in the handover information holding unit 115.
- the control unit 103 reads information necessary for the handover from the handover information holding unit 115 and outputs the information to the handover processing unit 117.
- control unit 103 instructs the transmission unit 105 to transmit ACK / NACK for the received signal. Further, the control unit 103 instructs the measurement unit 111 of the control unit 103 to measure necessary information in order to create a CSI report or a measurement result report (Measurement Report) according to the control information. Further, the control unit 103 creates a CSI report or a measurement result report (Measurement Report) based on the information input from the measurement unit 111, and outputs this to the transmission unit 105. Further, when information necessary for synchronization such as a random access response from the handover destination cell is input from the receiving unit 101, the control unit 103 outputs the information to the handover processing unit 117.
- the transmission unit 105 transmits ACK / NACK for the signal received from the cell to which the terminal UE1 is connected. Further, the transmission unit 105 transmits the CSI report or measurement result report input from the control unit 103 to the wireless communication apparatus that provides the cell. The transmission unit 105 transmits a random access preamble (RandomandAccess Preamble) to the handover destination cell in accordance with the notification from the handover processing unit 117. Furthermore, the transmission unit 105 transmits a handover completion message (Handover Complete) created by the control unit 103 to the handover destination cell.
- the measurement unit 111 instructs the reception unit 101 to receive a reference signal or measure received signal strength (RSSI).
- the reference signal is a cell reference signal (CRS), CSI-RS, DMRS or the like, and what is received is indicated by control information.
- the measurement unit 111 outputs information necessary for creating a CSI report or a measurement result report (Measurement Report) to the control unit 103.
- the measurement unit 111 outputs information necessary for the determination of the handover determination unit 113 based on a predetermined condition to the handover determination unit 113 in response to an instruction from the handover determination unit 113.
- the handover determination unit 113 requests the measurement unit 111 for information necessary for determination based on a predetermined condition included in the conditional handover command.
- the handover determining unit 113 determines whether or not to start the handover by determining whether or not the information input from the measuring unit 111 satisfies a predetermined condition.
- the handover determination unit 113 notifies the handover processing unit 117 of this.
- the handover information holding unit 115 holds information necessary for handover to a neighboring cell.
- the information necessary for handover to a neighboring cell is information included in a conditional handover command or a conventional handover command that does not require a condition. For example, measurement configuration (Measurement Configuration), mobility control information (Mobility Control) Information), radio resource settings (Radio Resource Configuration), security settings (Security Resource Configuration), and the like.
- the handover processing unit 117 When the information necessary for the handover to the adjacent cell is input, the handover processing unit 117 starts the handover process to the adjacent cell based on the information.
- the handover processing unit 117 notifies the transmission unit 105 to perform random access using the resource.
- the handover processing unit 117 performs the contention-based random access (Random Access Procedure) based on the information.
- the handover processing unit creates a handover complete message (Handover ⁇ Complete) and outputs it to the transmission unit 105.
- FIG. 3 is a flowchart showing an operation of the terminal UE1 of the first embodiment when the predetermined condition is the condition 1.
- the terminal UE1 receives a conditional handover command (step S101).
- the terminal UE1 determines whether or not the PDSCH reception quality of the handover destination cell is better than the PDSCH reception quality of the own cell (that is, the PDSCH reception quality currently used) (step S102). If the determination result of step S102 is No, the process proceeds to step S103, and if Yes, the process proceeds to step S104.
- step S103 terminal UE1 continues communication with an own cell and returns to step S102.
- the terminal UE1 stops communication with the own cell and starts handover to the handover destination cell.
- FIG. 4 is a flowchart showing an operation of the terminal UE1 of the first embodiment when the predetermined condition is the condition 3.
- the terminal UE1 receives a conditional handover command (step S101).
- the terminal UE1 determines whether or not the PDSCH reception quality of the handover destination cell is better than the PDSCH reception quality of the own cell (that is, the PDSCH reception quality currently used) (step S102). If the determination result in step S102 is No, the process proceeds to step S131. If Yes, the process proceeds to step S104.
- step S131 the terminal UE1 determines whether or not the reception quality of the PDCCH of the own cell satisfies the condition 2.
- step S131 determines whether the determination result of step S131 is No. If the determination result of step S131 is No, the process proceeds to step S103, and if Yes, the process proceeds to step S104.
- step S103 terminal UE1 continues communication with an own cell and returns to step S102.
- step S104 the terminal UE1 stops communication with the own cell and starts handover to the handover destination cell.
- FIG. 5 is a block diagram of the wireless communication device SNE1 that constitutes the wireless communication system of the first embodiment.
- the wireless communication device SNE1 of the first embodiment includes a wireless reception unit 121, a network reception unit 123, a network transmission unit 125, a wireless transmission unit 127, and a control unit 129.
- the control unit 129 includes a conditional handover determination unit 131 and a handover request unit 133.
- the radio reception unit 121 receives a response message to the individual control information transmitted from the terminal UE1, a measurement result report (Measurement Report), an ACK / NACK, a CSI report, and the like, and outputs them to the control unit 129.
- the network transmission unit 125 transmits a handover request message to the radio communication apparatus TNE that provides a handover destination cell. Further, the network transmission unit 125 transfers data addressed to the terminal UE1 to the radio communication device TNE. Further, the network transmission unit 125 notifies the radio communication apparatus TNE of a sequence number (Sequence Number) for starting transmission of data addressed to the terminal UE1 and a sequence number for receiving data from the terminal UE1.
- the network receiving unit 123 receives a handover response message including a conditional handover command transmitted from the radio communication apparatus TNE.
- the radio transmission unit 127 transmits a conditional handover command to the terminal.
- the control unit 129 outputs the measurement result report (Measurement Report) received by the wireless reception unit 121 to the conditional handover determination unit 131.
- the control unit 129 does not create an environment (for example, traffic) that the wireless communication device SNE1 currently provides to the terminal UE1.
- the conditional handover decision unit 131 includes information on the status of the data, presence / absence of CoMP, presence / absence of MIMO, number of antennas, presence / absence of heterogeneous network (Heterogeneous Network) environment, or PDSCH reception quality gain relative to PDCCH reception quality) Output.
- the control unit 129 When requested by the handover request unit 133 for information necessary for the handover request message, the control unit 129 outputs the setting information of the terminal UE1 and the like to the handover request unit 133. In addition, when the network reception unit 123 receives a handover response message including a conditional handover command transmitted from the radio communication apparatus TNE, the control unit 129 causes the radio transmission unit 127 to transmit a conditional handover command to the terminal UE1. Control.
- control unit 129 When the control unit 129 detects that the terminal UE1 has started the handover after transmitting the conditional handover command to the terminal UE1, the control unit 129 transfers the data addressed to the terminal UE1 to the radio communication device TNE that provides the handover destination cell.
- the network transmission unit 125 is controlled.
- the control unit 129 detects that the terminal UE1 has started handover, the control unit 129 sets a sequence number (Sequence Number) for starting transmission of data addressed to the terminal UE1 and a sequence number for receiving data from the terminal UE1 as the handover destination.
- the network transmission unit 125 is controlled to notify the wireless communication device TNE that provides the cell. Note that the control unit 129 determines that the terminal UE1 has started handover when at least one of the following conditions is satisfied.
- the value of the CSI report is “Out of Range”. 2. CSI report is not sent. 3. ACK / NACK is not sent.
- the handover source radio communication device SNE detects the completion of the handover at the timing when the handover destination radio communication device TNE notifies the handover source radio communication device SNE that the handover has been completed after the terminal UE1 has handed over. May be.
- the conditional handover determination unit 131 determines a handover destination cell based on the measurement result report received by the wireless reception unit 121 or the environment that the wireless communication device SNE1 currently provides to the terminal UE1, and the handover performed by the terminal UE1 As a type, a conditional handover or a normal handover is selected.
- the criterion for selecting the conditional handover by the conditional handover determination unit 131 is, for example, whether throughput is increased by staying in the cell to which the terminal UE1 is connected, and can the connection with the terminal UE1 be maintained as a traffic situation? It is. However, the criterion is not limited to this.
- conditional handover determination unit 131 When the conditional handover determination unit 131 selects the conditional handover, the conditional handover determination unit 131 outputs information indicating that the conditional handover is selected and information related to the handover destination cell to the handover request unit 133.
- the handover request unit 133 is necessary for the handover of the measurement result report received by the radio reception unit 121 when the information indicating that the conditional handover is selected from the conditional handover determination unit 131 and the information on the handover destination cell are input. Information is acquired from the control unit 129, and a handover request message is created. Note that the handover request unit 133 creates a handover request message including the environment that the wireless communication device SNE1 currently provides to the terminal UE1. The handover request unit 133 outputs a handover request message to the network transmission unit 125.
- the handover request message includes the environment that the wireless communication device SNE1 currently provides to the terminal UE1, so that the wireless communication device TNE that provides the handover destination cell has a predetermined condition included in the conditional handover command.
- the contents (any of the above conditions 1 to 11) can be determined.
- FIG. 6 is a block diagram of the wireless communication device TNE constituting the wireless communication system of the first embodiment.
- the wireless communication device TNE of the first embodiment includes a wireless reception unit 141, a network reception unit 143, a network transmission unit 145, a wireless transmission unit 147, and a control unit 149.
- the control unit 149 includes a conditional handover command creation unit 151.
- radio communication apparatus TNE counts a timer (not shown) that counts an elapsed time from transmission of a handover response message including a conditional handover command. ). The time when the timer can expire (expire) is longer than the time when the timer of the terminal UE1 can expire.
- the wireless reception unit 141 receives a random access preamble (Random Access Preamble) or a handover complete message (Handover Complete), which is a synchronization request from the terminal, and outputs it to the control unit.
- the network receiver 143 receives the handover request message transmitted from the radio communication device SNE1 that provides the handover source cell.
- the network transmission unit 145 transmits a handover response message including a conditional handover command to the radio communication device SNE1 that has transmitted the handover request message.
- the radio transmission unit 147 transmits a random access response message for the random access preamble transmitted from the terminal UE1 to the terminal UE1.
- the control unit creates a random access response message for the random access preamble received by the wireless reception unit 141 and outputs it to the wireless transmission unit 147. Further, when receiving the handover request message, the control unit 149 determines whether to accept the request. When accepting the handover request, the control unit 149 outputs the environment provided to the terminal that performs the handover and the handover request message to the conditional handover command creation unit 151.
- the conditional handover command creation unit 151 determines whether it is a conditional handover or a normal handover based on information input from the control unit 149 (a handover request message and an environment provided to a terminal that performs handover). Further, when the conditional handover command creating unit 151 determines to perform the conditional handover, the conditional handover command creating unit 151 sets a predetermined condition based on information input from the control unit 149 (a handover request message and an environment provided to the terminal that performs the handover). A conditional handover command including the predetermined condition is determined. The conditional handover command creation unit 151 outputs the created conditional handover command to the network transmission unit 145. The conditional handover command creation unit 151 creates a normal handover command when the handover request message requests a normal handover or when it is determined to perform a normal handover.
- the radio communication apparatus TNE determines a predetermined condition and creates a conditional handover command.
- the wireless communication device SNE1 determines a predetermined condition, and transmits the predetermined condition to the wireless communication device TNE together with the handover request message.
- the radio communication device TNE creates a conditional handover command based on a predetermined condition.
- the wireless communication device SNE1 After receiving a handover response message including a conditional handover command from the wireless communication device TNE, the wireless communication device SNE1 changes a predetermined condition indicated by the conditional handover command, and then transmits the conditional handover command to the terminal UE1. Also good.
- the terminal performs conditional handover sent from the radio communication apparatus.
- the handover is started when a predetermined condition is satisfied.
- the predetermined condition for starting handover is based on the reception quality of each PDSCH of the own cell and the neighboring cell that is the handover destination or the reception quality of the PDCCH of the own cell, or the elapsed time after receiving the conditional handover command. .
- the situation in which the terminal performs handover in the present embodiment can reliably receive the signal on the PDCCH of the own cell, compared to the case where the handover is simply performed at the intermediate point of the coverage of the PDCCH reception quality in each cell. . That is, the terminal can be handed over reliably in an appropriate situation.
- the wireless communication system of the second embodiment is different from the wireless communication system of the first embodiment in that the terminal is connected when it is determined that the terminal starts handover based on a predetermined condition indicated by the conditional handover command. That is, the terminal transmits a “handover start message” to the wireless communication apparatus that provides its own cell. Except for this point, the second embodiment is the same as the first embodiment. In FIGS. 7 to 10, the corresponding components or steps of the first embodiment are denoted by the same reference numerals.
- FIG. 7 is a diagram illustrating an example of a timing chart when the terminal UE2 performs a handover in the wireless communication system according to the second embodiment.
- the radio communication device SNE2 that provides the own cell to which the terminal UE2 is connected receives a measurement result report (Measurement Report) from the terminal UE2, and the condition is the same as in the first embodiment. Implementation of attached handover and the handover destination are determined.
- the radio communication device SNE2 transmits a handover request message to the handover destination radio communication device TNE.
- the radio communication device TNE performs a handover approval process.
- the radio communication device TNE transmits a handover response message including a conditional handover command to the radio communication device SNE2.
- the radio communication apparatus SNE2 that has received the handover response message transmits a conditional handover command to the terminal UE2.
- the conditional handover command includes a predetermined condition necessary for the terminal UE2 to determine when to start handover.
- the terminal UE2 does not start the handover until the predetermined condition described in the first embodiment is satisfied, and continues the communication with the radio communication device SNE2. In other words, when the predetermined condition is satisfied, the terminal UE2 transmits a “handover start message” to the radio communication device SNE2. Next, the terminal UE2 stops communication with the radio communication device SNE2, and starts handover to an adjacent cell provided by the radio communication device TNE indicated by the conditional handover command. Further, when receiving the handover start message transmitted from the terminal UE2, the radio communication device SNE2 starts data transfer of data addressed to the terminal UE2 to the radio communication device TNE.
- the radio communication device SNE2 notifies the radio communication device TNE of a sequence number (Sequence Number) for starting transmission of data addressed to the terminal UE2 and a sequence number for receiving data from the terminal UE2. Note that the radio communication device SNE2 detects that the terminal UE2 has started handover by receiving the handover start message.
- a sequence number Sequence Number
- the radio communication device SNE2 detects that the terminal UE2 has started handover by receiving the handover start message.
- the terminal UE2 that has started the handover first sends a random access preamble (Random Access Preamble) as an uplink synchronization establishment request to the radio communication apparatus TNE that is instructed by the conditional handover command.
- a random access preamble Random Access Preamble
- the terminal UE2 transmits a handover complete message (Handover ⁇ Complete) to the radio communication device TNE.
- FIG. 8 is a block diagram of the terminal UE2 constituting the wireless communication system of the second embodiment.
- the terminal UE2 of the second embodiment includes a reception unit 101, a control unit 203, and a transmission unit 105.
- the control unit 203 includes a measurement unit 111, a handover determination unit 113, a handover information holding unit 115, a handover processing unit 117, and a handover start message creation unit 219. Since the components other than the handover start message creation unit 219 of the control unit 203 are the same as those in the first embodiment, description thereof will be simplified or omitted.
- the handover start message creation unit 219 creates a handover start message that informs the start of handover.
- the handover start message is transmitted from the transmission unit 105 to the wireless communication device SNE2.
- the control unit 203 reads information necessary for the handover from the handover information holding unit 115 and outputs the information to the handover processing unit 117.
- the control unit 203 reads information necessary for the handover from the handover information holding unit 115 after the ACK (acknowledgment notification) from the wireless communication device SNE2 in response to the handover start message is received by the reception unit 101, and sends it to the handover processing unit 117. It may be output.
- a margin of time required for the network to prepare for accepting the handover of the terminal UE2 (for example, a margin of time required for data transfer addressed to the terminal UE2). Design is simplified.
- FIG. 9 is a flowchart showing an operation of the terminal UE2 of the second embodiment when the predetermined condition is the condition 1.
- the terminal UE2 receives a conditional handover command (step S101).
- the terminal UE2 determines whether or not the PDSCH reception quality of the handover destination cell is better than the reception quality of the PDSCH of the own cell (that is, the PDSCH currently used) (step S102). If the determination result of step S102 is No, the process proceeds to step S103, and if Yes, the process proceeds to step S204.
- step S103 the terminal UE2 continues communication with the currently connected cell and returns to step S102.
- the terminal UE2 transmits a handover start message to notify the radio communication apparatus SNE2 of the start of handover.
- the terminal UE2 stops communication with the currently connected cell and starts handover to the handover destination cell (step S104).
- the terminal UE2 stops the conditional handover process and sends a message indicating that the communication with the currently connected cell is continued. It may be sent to SNE2. Note that even when the predetermined condition is the conditions 12 to 14, the terminal UE2 stops the conditional handover process when the condition is satisfied, and displays a message indicating that communication with the currently connected cell is continued. You may transmit to radio
- FIG. 10 is a block diagram of the wireless communication device SNE2 constituting the wireless communication system of the second embodiment.
- the same reference numerals are assigned to components common to the wireless communication device SNE1 of the first embodiment illustrated in FIG. 5.
- the wireless communication device SNE2 of the second embodiment includes a wireless reception unit 221, a network reception unit 123, a network transmission unit 125, a wireless transmission unit 127, and a control unit 229.
- the control unit 229 includes a conditional handover determination unit 131 and a handover request unit 133.
- the radio reception unit 221 receives the handover start message transmitted from the terminal UE2 and outputs it to the control unit 229.
- the control unit 229 starts transferring data addressed to the terminal UE2 to the radio communication device TNE.
- the radio communication device SNE2 may notify the radio communication device TNE to reserve a dedicated resource for random access.
- the wireless communication device TNE (Target NE) of the second embodiment has the same configuration and operation as the wireless communication device TNE of the first embodiment.
- the wireless communication device can quickly detect that the terminal starts handover by a handover start message transmitted from the terminal to the wireless communication device that provides the own cell. Further, thereafter, the wireless communication apparatus can quickly start the process of transferring the data addressed to the terminal to the wireless communication apparatus that is the handover destination. Further, if the handover destination radio communication apparatus notifies the handover source radio communication apparatus that the terminal is handing over, the handover destination radio communication apparatus does not allocate resources to the terminal after the terminal starts handover. Tesumu. For this reason, it is possible to effectively use radio resources in the radio communication apparatus that is the handover source.
- the wireless communication apparatus providing the own cell may use both the method of detecting that the terminal of the first embodiment has started handover and the reception of the handover start message in the present embodiment. By doing so, it is possible to cope with the case where the terminal starts handover without the wireless communication apparatus receiving the handover start message due to the deterioration of the radio wave environment.
- FIGS. 11 to 14 A radio communication system according to the third embodiment will be described with reference to FIGS.
- the difference between the wireless communication system of the third embodiment and the wireless communication system of the first embodiment is that when it is determined that the wireless communication apparatus starts handover while the terminal is performing conditional handover processing, The wireless communication apparatus transmits a “handover start instruction message” to the terminal.
- the second embodiment is the same as the first embodiment.
- FIGS. 11 to 14 the corresponding components or steps of the first embodiment are denoted by the same reference numerals.
- FIG. 11 is a diagram illustrating an example of a timing chart when the terminal UE3 performs a handover in the wireless communication system according to the third embodiment.
- the radio communication device SNE3 that provides the own cell to which the terminal UE3 is connected receives a measurement result report (Measurement Report) and the like from the terminal UE3, and the condition is the same as in the first embodiment. Implementation of attached handover and the handover destination are determined.
- the radio communication device SNE3 transmits a handover request message to the handover destination radio communication device TNE.
- the radio communication device TNE performs a handover approval process.
- the radio communication device TNE transmits a handover response message including a conditional handover command to the radio communication device SNE3.
- the wireless communication device SNE3 that has received the handover response message transmits a conditional handover command to the terminal UE3.
- the conditional handover command includes a predetermined condition necessary for the terminal UE3 to determine the timing for starting the handover.
- the terminal UE3 performs handover until it receives a handover start instruction message (to be described later) transmitted from the radio communication apparatus SNE3 or until the predetermined condition described in the first embodiment is satisfied.
- the communication with the wireless communication device SNE3 is continued.
- the terminal UE3 stops the communication with the radio communication apparatus SNE3 and is provided by the radio communication apparatus TNE indicated by the conditional handover command. Initiate handover to the cell.
- the radio communication device SNE3 After transmitting the handover start instruction message, when the radio communication device SNE3 detects that the terminal UE3 has started handover, the radio communication device SNE3 starts transferring data addressed to the terminal UE3 to the radio communication device TNE. Further, the radio communication device SNE3 notifies the radio communication device TNE of a sequence number (Sequence Number) for starting transmission of data addressed to the terminal UE3 and a sequence number for receiving data from the terminal UE3.
- a sequence number Sequence Number
- the wireless communication device SNE3 detects that the terminal UE3 has started handover by transmitting a handover start instruction message.
- the radio communication device SNE3 may use both the method of the first embodiment and the transmission of the handover start instruction message according to this embodiment as a method of detecting that the terminal UE3 has started handover. . By doing so, the radio communication device SNE3 can detect the handover even when the terminal UE3 starts the handover by satisfying a predetermined condition.
- the terminal UE1 that has started the handover first sends a random access preamble (Random Access Preamble) as an uplink synchronization establishment request to the radio communication device TNE indicated by the conditional handover command.
- a random access preamble Random Access Preamble
- the terminal UE3 transmits a handover complete message (Handover Complete) to the wireless communication device TNE.
- Handover from the own cell provided by the wireless communication device SNE3 to the adjacent cell provided by the wireless communication device TNE is performed.
- FIG. 12 is a block diagram of a terminal UE3 configuring the wireless communication system according to the third embodiment.
- the terminal UE3 of the third embodiment includes a reception unit 101, a control unit 303, and a transmission unit 105.
- the control unit 303 includes a measurement unit 111, a handover determination unit 313, a handover information holding unit 115, and a handover processing unit 117. Since the components other than the handover determination unit 313 of the control unit 303 are the same as those in the first embodiment, the description is simplified or omitted.
- the handover determination unit 313 requests the measurement unit 111 for information necessary for determination based on a predetermined condition included in the conditional handover command.
- the handover determining unit 313 determines whether or not to start the handover by determining whether or not the information input from the measuring unit 111 satisfies a predetermined condition.
- the reception unit 101 receives the handover start instruction message
- the handover determination unit 313 determines the start of the handover.
- the handover determination unit 313 notifies the control unit 203 of this.
- FIG. 13 is a flowchart showing an operation of the terminal UE3 of the third embodiment when the predetermined condition is the condition 1.
- the terminal UE3 receives a conditional handover command (step S101).
- the terminal UE3 determines whether or not the PDSCH reception quality of the handover destination cell is better than the reception quality of the own cell PDSCH (that is, the PDSCH currently used) (step S102). If the determination result in step S102 is No, the process proceeds to step S303, and if Yes, the process proceeds to step S104.
- step S303 the terminal UE3 determines whether a handover start instruction message has been received from the currently connected cell.
- step S303 the process proceeds to step S103, and if Yes, the process proceeds to step S104.
- step S103 the terminal UE3 continues communication with the currently connected cell and returns to step S102.
- step S104 the terminal UE3 stops communication with the currently connected cell and starts handover to the handover destination cell.
- FIG. 14 is a block diagram of a wireless communication device SNE3 that constitutes the wireless communication system of the third embodiment.
- the wireless communication device SNE3 according to the third embodiment includes a wireless reception unit 121, a network reception unit 123, a network transmission unit 125, a wireless transmission unit 127, and a control unit 329.
- the control unit 329 further includes a handover start determination unit 335 in addition to the conditional handover determination unit 131 and the handover request unit 133. Since the components other than the handover start determination unit 335 are the same as those in the first embodiment, the description is simplified or omitted.
- the handover start determination unit 335 starts the handover of the terminal UE3 based on a predetermined condition included in the conditional handover command, a currently provided environment, a CSI report or a measurement result report received by the radio reception unit 121, and the like. judge. For example, the handover start determination unit 335 estimates the difference between the PDSCH reception quality of the own cell and the PDCCH reception quality from the currently provided environment or the CSI report, and determines the adjacent PDSCH reception quality of the own cell from the measurement result report. By comparing the PDSCH reception qualities of the cells, the start of the handover of the terminal UE3 is determined based on the predetermined condition described in the first embodiment.
- the handover start determination unit 335 determines the start of the handover, the handover start determination unit 335 creates a handover start instruction message.
- the handover start instruction message is transmitted from the wireless transmission unit 127 to the terminal UE3.
- the control unit 329 starts transferring data addressed to the terminal UE3 to the radio communication device TNE.
- the terminal after a terminal receives a conditional handover command, the terminal performs an instruction from a wireless communication apparatus that provides its own cell regardless of timing based on a predetermined condition indicated by the conditional handover command. Can also initiate a handover.
- the conditions for the terminal UE3 to start the handover are that the handover start instruction message is received and the conditions 2, 4, 5, and 8 out of the conditions 1 to 11 described in the first embodiment. , 9 may be limited.
- the terminal UE3 can determine the start of handover by a conventional measurement method, and the difference between the reception quality of the PDSCH of the own cell and the reception quality of the adjacent cell PDSCH measured by the terminal UE3 by the radio communication device SNE3.
- the handover timing can be determined in consideration of the above. As described above, since the wireless communication device SNE3 and the terminal UE3 do not perform the same determination under the same conditions, it is possible to easily determine an appropriate handover timing.
- FIGS. 15 to 17 A wireless communication system according to the fourth embodiment will be described with reference to FIGS.
- the wireless communication system of the fourth embodiment is different from the wireless communication system of the first embodiment in that the contents can be changed after the conditional handover command is transmitted to the terminal. Except for this point, the second embodiment is the same as the first embodiment.
- FIGS. 15 to 17 the components corresponding to the first embodiment are denoted by the same reference numerals.
- FIG. 15 is a diagram illustrating an example of a timing chart when the terminal UE4 performs a handover in the wireless communication system according to the fourth embodiment.
- the radio communication device SNE4 that provides the own cell to which the terminal UE4 is connected receives a measurement result report (Measurement Report) and the like from the terminal UE4, and performs conditional handover and the handover destination. decide.
- the radio communication device SNE4 transmits a handover request message to the handover destination radio communication device TNE.
- the radio communication device TNE performs a handover approval process.
- the radio communication device TNE transmits a handover response message including a conditional handover command to the radio communication device SNE4.
- the wireless communication device SNE4 that has received the handover response message transmits a conditional handover command to the terminal UE4.
- the conditional handover command includes a predetermined condition necessary for the terminal UE4 to determine when to start handover.
- the terminal UE4 Even if the terminal UE4 receives the conditional handover command, the terminal UE4 does not start the handover until the predetermined condition described in the first embodiment is satisfied, and continues the communication with the radio communication device SNE4. After that, when the terminal UE4 receives the conditional handover command again until the predetermined condition is satisfied, the terminal UE4 changes to the processing based on the newly received conditional handover command. Note that, when the terminal UE4 receives the conditional handover command again until the predetermined condition is satisfied, the terminal UE4 may overwrite the previously received conditional handover command with the newly received conditional handover command. Also, if the cancellation of the conditional handover command is instructed from the radio communication apparatus SNE4 until the predetermined condition is satisfied, the terminal UE4 discards the information on the conditional handover command that has already been received. .
- the terminal UE4 stops communication with the radio communication device SNE4 and starts handover to the adjacent cell provided by the radio communication device TNE4 instructed by the conditional handover command.
- the radio communication device SNE4 detects that the terminal UE4 has started handover by some method, the radio communication device SNE4 starts transferring data addressed to the terminal UE4 to the radio communication device TNE. Further, the radio communication device SNE4 notifies the radio communication device TNE of a sequence number (Sequence Number) for starting transmission of data addressed to the terminal UE4 and a sequence number for receiving data from the terminal UE4.
- a sequence number Sequence Number
- the terminal UE4 that has started handover first sends a random access preamble (Random Access Preamble) as an uplink synchronization establishment request to the radio communication apparatus TNE that is instructed by the conditional handover command.
- a random access preamble Random Access Preamble
- the terminal UE4 transmits a handover completion message (Handover Complete) to the wireless communication device TNE.
- FIG. 16 is a block diagram of a terminal UE4 configuring the wireless communication system according to the fourth embodiment.
- the terminal UE4 of the fourth embodiment includes a reception unit 101, a control unit 403, and a transmission unit 105.
- the control unit 403 includes a measurement unit 111, a handover determination unit 413, a handover information holding unit 415, and a handover processing unit 117. Since the components other than the handover determination unit 413 and the handover information holding unit 415 of the control unit 403 are the same as those in the first embodiment, the description is simplified or omitted.
- the handover determining unit 413 confirms whether or not the predetermined condition used for determining the start of the handover is already held. If the handover determination unit 413 already holds a predetermined condition, the handover determination unit 413 determines whether or not there is a difference between the predetermined condition indicated by the newly received conditional handover command and the predetermined condition already held. judge. When there is a difference, the handover determination unit 413 changes the predetermined condition by adding the difference to the predetermined condition already held. Note that the handover determination unit 413 may overwrite the new predetermined condition with the previous predetermined condition. When the predetermined condition is not held, the handover determining unit 413 performs the same operation as in the first embodiment using the predetermined condition. Note that the handover determining unit 413 discards a predetermined condition already held when the receiving unit 101 receives a conditional handover cancellation message (remove).
- the handover information holding unit 415 confirms whether information necessary for handover to the neighboring cell is already held. When the information is already held, the handover information holding unit 415 determines whether there is a difference from the information necessary for the handover indicated by the new conditional handover command. If there is a difference, the handover information holding unit 415 changes the held information by adding the difference information to the held information. Note that newly input information may be overwritten on previous information. When the receiving unit 101 receives a conditional handover cancellation message (remove), the handover information holding unit 415 discards information already held for handover.
- FIG. 17 is a block diagram of a wireless communication device SNE4 that constitutes the wireless communication system of the fourth embodiment.
- the wireless communication device SNE4 according to the fourth embodiment includes a wireless reception unit 121, a network reception unit 123, a network transmission unit 125, a wireless transmission unit 127, and a control unit 429.
- the control unit 429 includes a conditional handover determination unit 431 and a handover request unit 133.
- the components other than the conditional handover determination unit 431 of the control unit 429 are the same as those in the first embodiment, and thus the description is simplified or omitted.
- the conditional handover determination unit 431 determines whether to change the conditional handover command based on the CSI report or measurement result report from the terminal UE4. When the conditional handover determination unit 431 determines that it is better to change the handover destination, the conditional handover determination unit 431 outputs information regarding the conditional handover and the handover destination cell to the handover request unit. Further, the conditional handover determination unit 431 determines whether or not to cancel the conditional handover command transmitted to the terminal UE4 based on the CSI report or measurement result report of the terminal UE4. If the conditional handover determination unit 431 determines to cancel the conditional handover command, the conditional handover determination unit 431 outputs that fact to the control unit 429.
- the control unit 429 determines whether or not there is a change in the conditional handover command. When the control unit 429 determines that the conditional handover command is changed, the control unit 429 updates the data transfer destination cell according to the newly input conditional handover command. In addition, when receiving from the conditional handover determination unit 431 that the conditional handover command is to be canceled, the control unit 429 creates a conditional handover cancellation message and outputs it to the radio transmission unit 127. Note that when the conditional handover command is changed or canceled, the control unit 429 notifies the handover destination cell that has already been set of the change or cancellation of the conditional handover command. You may output to 125.
- the handover destination can be changed or the handover can be canceled according to the movement of the terminal, and a better connection to the cell can be maintained for the terminal.
- multi-point cooperation (Coordinated Multiple Point: CoMP) has been described as an example.
- the present disclosure is applied when there is a difference between the PDCCH reception quality coverage and the PDSCH reception quality coverage. Can do.
- the present disclosure can be applied to a heterogeneous network environment.
- a macro cell may apply ABS (Almost Blank ⁇ ⁇ ⁇ Subframe), which is a subframe that does not transmit a signal or transmits at a low power.
- ABS Almost Blank ⁇ ⁇ ⁇ Subframe
- a terminal using a pico cell within the coverage of the macro cell can extend the time to connect to the pico cell by applying the present disclosure.
- the maximum offload between the macro cell and the pico cell can be performed.
- the present disclosure can be applied to a wireless communication system in which the number of antennas differs between wireless communication devices. For example, when a terminal connected to a wireless communication apparatus operating with four antennas is handed over to a wireless communication apparatus operating with two antennas, the terminal is connected longer with the wireless communication apparatus with four antennas. Can do. As a result, the terminal can enjoy high throughput.
- each functional block used in the description of each of the above embodiments is typically realized as an LSI that is an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include a part or all of them.
- the name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.
- the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible.
- An FPGA Field Programmable Gate Array
- a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.
- An antenna port refers to a logical antenna composed of one or a plurality of physical antennas. That is, the antenna port does not necessarily indicate one physical antenna, but may indicate an array antenna composed of a plurality of antennas.
- LTE Long Term Evolution
- An antenna port may be defined as a minimum unit for multiplying a weight of a precoding vector.
- the wireless communication terminal according to the present disclosure is useful as a wireless communication terminal that performs handover to an adjacent cell in an appropriate situation even when the reception quality of the data channel signal in the own cell is different from the reception quality of the control channel signal. It is.
- UE1, UE2, UE3, UE4 Wireless communication terminal 101 Receiving unit 103, 203, 303, 403 Control unit 105 Transmitting unit 111 Measuring unit 113, 313, 413 Handover determining unit 115, 415 Handover information holding unit 117 Handover processing unit 219 Start of handover Message creation department SNE1, SNE2, SNE3, SNE4 Radio communication devices 121, 221 Radio reception unit 123 Network reception unit 125 Network transmission unit 127 Radio transmission units 129, 229, 329, 429 Control units 131, 431
Abstract
Description
本開示に係る無線通信システムの実施形態を説明する前に、従来の無線通信システムにおける課題について図18及び図19を参照して説明する。図18は、自セルから隣接セルに端末がハンドオーバするタイミングの一例を示す図である。図18に示す例では、各無線通信基地局が提供するセルのPDSCHの受信品質が一定以上のカバレッジとPDCCH(物理下り制御チャネル(Physical Downlink Control Channel))の受信品質が一定以上のカバレッジは等しい。したがって、無線通信基地局eNB1のセルに接続中の端末が図18に示す地点Aに移動すると、無線通信基地局eNB2が提供する隣接セルへのハンドオーバが行われる。なお、地点Aは、各無線通信基地局が提供するセルのPDCCHの受信品質のカバレッジの中間地点である。
図1~図6を参照して、第1の実施形態の無線通信システムについて説明する。第1の実施形態の無線通信システムは、上記説明した端末及び無線通信装置から構成される。端末は、ダウンリンクで無線通信装置からセル毎に送信された参照信号を受信して、定められた計算式に基づいて導出される測定結果を無線通信装置に報告する。無線通信装置は、各端末に対して無線リソース(例えば、周波数領域又は時間領域での周波数帯域)の割り当て及び管理を行い、端末のための無線アクセスネットワークのアクセスポイントの役割を有する。また、無線通信装置は、端末からの測定結果報告に基づいて他のセルへのハンドオーバが必要と判断した際にハンドオーバ処理を行う機能を有する。
条件1は、端末により測定された、条件付きハンドオーバコマンドが示すハンドオーバ先のセル(隣接セル)におけるPDSCHの受信品質が、自セルにおけるPDSCHの受信品質よりも良いことである。条件1をハンドオーバの開始条件として設定することによって、端末がPDSCHの受信品質が高いセルに接続する時間が長くなる。このため、無線資源の有効活用ができるとともに、端末の周波数利用効率を高い水準で維持できる。
条件2は、端末が現在接続しているセル(自セル)のPDCCHの当該端末により測定された受信品質が閾値よりも低いことである。条件2をハンドオーバの開始条件として設定すれば、端末が自セルからのデータを受信できなくなった直後又は端末が自セルからのデータを受信できなくなる直前にハンドオーバが開始される。このため、端末がデータを受信できない無通信期間を最小限にすることができる。
条件3は、条件1又は条件2を満たすことである。条件3をハンドオーバの開始条件として設定することによって、PDSCHの受信品質を考慮しつつ無通信期間を最小限に抑えることができる。
条件4は、条件付きハンドオーバコマンドの受信からの経過時間が「ハンドオーバ開始制限時間」に到達することである。端末は、条件4を満たす直前にハンドオーバを開始する。条件4をハンドオーバの開始条件として設定することによって、ハンドオーバ先の無線通信装置が、ハンドオーバしてくる端末のために待機する時間を制限することができる。なお、端末がハンドオーバを開始して実際に隣接セルにハンドオーバするまでの遅延がハンドオーバ先の無線通信装置によって考慮されるのであれば、端末は、条件4を満たした後にハンドオーバを開始してもよい。この場合、ハンドオーバ先の無線通信装置における、ハンドオーバしてくる端末のためのリソースを予約しておく期間を最小限に抑えることができる。
条件5は、ハンドオーバの開始のための条件ではなく、条件付きハンドオーバの処理を中止するための条件である。条件5は、条件付きハンドオーバコマンドの受信からの経過時間が「条件付きハンドオーバ取消時間」に到達することである。端末は、条件5を満たすと条件付きハンドオーバの処理を中止する。条件5を条件付きハンドオーバの中止条件として設定することによって、ハンドオーバ先の無線通信装置が、ハンドオーバしてくる端末のために待機する時間を制限することができる。また、端末は、条件5を満たす直前に条件付きハンドオーバの処理を中止してもよい。この場合、ハンドオーバ先の無線通信装置における、ハンドオーバしてくる端末のためのリソースを予約しておく期間を最小限に抑えることができる。
条件6は、条件1又は条件4を満たすことである。
条件7は、条件5を満たす前に条件1を満たすことである。なお、条件1を満たす前に条件5を満たすと、端末は、条件付きハンドオーバの処理を中止する。
条件8は、条件2又は条件4を満たすことである。
条件9は、条件5を満たす前に条件2を満たすことである。なお、条件2を満たす前に条件5を満たすと、端末は、条件付きハンドオーバの処理を中止する。
条件10は、条件3又は条件4を満たすことである。言い換えると、条件10は、条件1、条件2又は条件4を満たすことである。
条件11は、条件5を満たす前に条件3を満たすことである。なお、条件3を満たす前に条件5を満たすと、端末は、条件付きハンドオーバの処理を中止する。
条件12は、ハンドオーバの開始のための条件ではなく、条件付ハンドオーバの処理を中止するための条件である。自セルのPDCCHの当該端末により測定された受信品質が閾値よりも高いことである。
条件13は、ハンドオーバの開始のための条件ではなく、条件付ハンドオーバの処理を中止するための条件である。自セルのPDCCHの当該端末により測定された受信品質がハンドオーバ先のPDCCHの当該端末により測定された受信品質が高いことである。なお、受信品質にオフセットを加味して判定してもよい。
条件14は、ハンドオーバの開始のための条件ではなく、条件付ハンドオーバの処理を中止するための条件である。自セルのPDSCHの当該端末により測定された受信品質がハンドオーバ先のPDCCHの当該端末により測定された受信品質が高いことである。
図2は、第1の実施形態の無線通信システムを構成する端末UE1のブロック図である。図2に示すように、第1の実施形態の端末UE1は、受信部101と、制御部103と、送信部105とを備える。制御部103は、測定部111と、ハンドオーバ判定部113と、ハンドオーバ情報保持部115と、ハンドオーバ処理部117とを有する。なお、上記説明した所定の条件が条件4~条件11のいずれかであるとき、端末UE1は、条件付きハンドオーバコマンドの受信からの経過時間をカウントするタイマー(図示せず)を有する。タイマーは、条件付きハンドオーバコマンドが設定する時間をカウントするときれる(expire)。
さらに、制御部103は、受信部101からハンドオーバ先のセルからのランダムアクセス応答など同期に必要な情報が入力されると、当該情報をハンドオーバ処理部117に出力する。
図3は、所定の条件が条件1である場合の第1の実施形態の端末UE1の動作を示すフローチャートである。図3に示すように、端末UE1は、条件付きハンドオーバコマンドを受信する(ステップS101)。端末UE1は、ハンドオーバ先のセルのPDSCHの受信品質が、自セルのPDSCHの受信品質(すなわち、現在使用しているPDSCHの受信品質)よりも良いか否かを判定する(ステップS102)。ステップS102の判定結果がNoの場合はステップS103へ移行し、Yesの場合はステップS104へ移行する。ステップS103では、端末UE1は、自セルとの通信を継続し、ステップS102に戻る。ステップS104では、端末UE1は、自セルとの通信を停止し、ハンドオーバ先のセルへのハンドオーバを開始する。
図5は、第1の実施形態の無線通信システムを構成する無線通信装置SNE1のブロック図である。図5に示すように、第1の実施形態の無線通信装置SNE1は、無線受信部121と、ネットワーク用受信部123と、ネットワーク用送信部125と、無線送信部127と、制御部129とを備える。制御部129は、条件付きハンドオーバ判定部131と、ハンドオーバ要求部133とを有する。
1.CSI報告の値が「Out of Range」である。
2.CSI報告が送信されてこない。
3.ACK/NACKが送信されてこない。
なお、ハンドオーバ先の無線通信装置TNEが、端末UE1がハンドオーバした後に、ハンドオーバ元の無線通信装置SNEにハンドオーバが完了したことを通知するタイミングで、ハンドオーバ元の無線通信装置SNEがハンドオーバの完了を検知してもよい。
図6は、第1の実施形態の無線通信システムを構成する無線通信装置TNEのブロック図である。図6に示すように、第1の実施形態の無線通信装置TNEは、無線受信部141と、ネットワーク用受信部143と、ネットワーク用送信部145と、無線送信部147と、制御部149とを備える。制御部149は、条件付きハンドオーバコマンド作成部151を有する。なお、上記説明した所定の条件が条件4~条件11のいずれかであるとき、無線通信装置TNEは、条件付きハンドオーバコマンドを含むハンドオーバ応答メッセージの送信からの経過時間をカウントするタイマー(図示せず)を有する。当該タイマーがきれる(expireする)時間は、端末UE1のタイマーがきれる時間よりも長い。
1.無線通信装置SNE1が所定の条件を決定し、ハンドオーバ要求メッセージとともに当該所定の条件を無線通信装置TNEに送信する。無線通信装置TNEは所定の条件に基づいて条件付きハンドオーバコマンドを作成する。
2.無線通信装置SNE1は、条件付きハンドオーバコマンドを含むハンドオーバ応答メッセージを無線通信装置TNEから受信した後に、条件付きハンドオーバコマンドが示す所定の条件を変更した上で条件付きハンドオーバコマンドを端末UE1に送信してもよい。
図7~図10を参照して、第2の実施形態の無線通信システムについて説明する。第2の実施形態の無線通信システムが第1の実施形態の無線通信システムと異なる点は、条件付きハンドオーバコマンドが示す所定の条件に基づいて端末がハンドオーバを開始すると判断した際に、端末が接続している自セルを提供する無線通信装置に当該端末が「ハンドオーバ開始メッセージ」を送信することである。この点以外は、第1の実施形態と同様であり、図7~図10において、第1の実施形態の該当する構成要素又はステップには同じ符号が付されている。
図8は、第2の実施形態の無線通信システムを構成する端末UE2のブロック図である。図8では、図2に示した第1の実施形態の端末UE1と共通する構成要素には同じ参照符号が付されている。図8に示すように、第2の実施形態の端末UE2は、受信部101と、制御部203と、送信部105とを備える。制御部203は、測定部111と、ハンドオーバ判定部113と、ハンドオーバ情報保持部115と、ハンドオーバ処理部117と、ハンドオーバ開始メッセージ作成部219とを有する。制御部203のハンドオーバ開始メッセージ作成部219を除く構成要素は、第1の実施形態と同じであるため、説明を簡略化又は省略する。
図9は、所定の条件が条件1である場合の第2の実施形態の端末UE2の動作を示すフローチャートである。図9に示すように、端末UE2は、条件付きハンドオーバコマンドを受信する(ステップS101)。端末UE2は、ハンドオーバ先のセルのPDSCHの受信品質が、自セルのPDSCH(すなわち、現在使用しているPDSCH)の受信品質よりも良いか否かを判定する(ステップS102)。ステップS102の判定結果がNoの場合はステップS103へ移行し、Yesの場合はステップS204へ移行する。ステップS103では、端末UE2は、現在接続しているセルとの通信を継続し、ステップS102にもどる。ステップS204では、端末UE2は、無線通信装置SNE2にハンドオーバの開始を伝えるためにハンドオーバ開始メッセージを送信する。次に、端末UE2は、現在接続しているセルとの通信を停止し、ハンドオーバ先のセルへのハンドオーバを開始する(ステップS104)。
図10は、第2の実施形態の無線通信システムを構成する無線通信装置SNE2のブロック図である。図10では、図5に示した第1の実施形態の無線通信装置SNE1と共通する構成要素には、同じ参照符号が付されている。図10に示すように、第2の実施形態の無線通信装置SNE2は、無線受信部221と、ネットワーク用受信部123と、ネットワーク用送信部125と、無線送信部127と、制御部229とを備える。制御部229は、条件付きハンドオーバ判定部131と、ハンドオーバ要求部133とを有する。
図11~図14を参照して、第3の実施形態の無線通信システムについて説明する。第3の実施形態の無線通信システムが第1の実施形態の無線通信システムと異なる点は、端末が条件付きハンドオーバの処理を行っている最中に無線通信装置がハンドオーバを開始すると判断した際、当該無線通信装置が「ハンドオーバ開始指示メッセージ」を端末に送信することである。この点以外は、第1の実施形態と同様であり、図11~図14において、第1の実施形態の該当する構成要素又はステップには同じ符号が付されている。
図12は、第3の実施形態の無線通信システムを構成する端末UE3のブロック図である。図12では、図2に示した第1の実施形態の端末UE1と共通する構成要素には同じ参照符号が付されている。図12に示すように、第3の実施形態の端末UE3は、受信部101と、制御部303と、送信部105とを備える。制御部303は、測定部111と、ハンドオーバ判定部313と、ハンドオーバ情報保持部115と、ハンドオーバ処理部117とを有する。制御部303のハンドオーバ判定部313を除く構成要素は、第1の実施形態と同じであるため、説明を簡略化又は省略する。
図13は、所定の条件が条件1である場合の第3の実施形態の端末UE3の動作を示すフローチャートである。図13に示すように、端末UE3は、条件付きハンドオーバコマンドを受信する(ステップS101)。端末UE3は、ハンドオーバ先のセルのPDSCHの受信品質が、自セルのPDSCH(すなわち、現在使用しているPDSCH)の受信品質よりも良いか否かを判定する(ステップS102)。ステップS102の判定結果がNoの場合はステップS303へ移行し、Yesの場合はステップS104へ移行する。ステップS303では、端末UE3は、現在接続しているセルからハンドオーバ開始指示メッセージを受信したか否かを判定する。ステップS303の判定結果がNoの場合はステップS103へ移行し、Yesの場合はステップS104へ移行する。ステップS103では、端末UE3は、現在接続しているセルとの通信を継続し、ステップS102にもどる。ステップS104では、端末UE3は、現在接続しているセルとの通信を停止し、ハンドオーバ先のセルへのハンドオーバを開始する。
図14は、第3の実施形態の無線通信システムを構成する無線通信装置SNE3のブロック図である。図14では、図5に示した第1の実施形態の無線通信装置SNE1と共通する構成要素には、同じ参照信号が付されている。図14に示すように、第3の実施形態の無線通信装置SNE3は、無線受信部121と、ネットワーク用受信部123と、ネットワーク用送信部125と、無線送信部127と、制御部329とを備える。制御部329は、条件付きハンドオーバ判定部131及びハンドオーバ要求部133に加えて、ハンドオーバ開始判定部335をさらに有する。ハンドオーバ開始判定部335を除く構成要素は、第1の実施形態と同じであるため、説明を簡略化又は省略する。
図15~図17を参照して、第4の実施形態の無線通信システムについて説明する。第4の実施形態の無線通信システムが第1の実施形態の無線通信システムと異なる点は、条件付きハンドオーバコマンドを端末に送信した後にその内容を変更できることである。この点以外は、第1の実施形態と同様であり、図15~図17において、第1の実施形態に該当する構成要素には同じ符号が付されている。
図16は、第4の実施形態の無線通信システムを構成する端末UE4のブロック図である。図16では、図2に示した第1の実施形態の端末UE1と共通する構成要素には同じ参照符号が付されている。図16に示すように、第4の実施形態の端末UE4は、受信部101と、制御部403と、送信部105とを備える。制御部403は、測定部111と、ハンドオーバ判定部413と、ハンドオーバ情報保持部415と、ハンドオーバ処理部117とを有する。制御部403のハンドオーバ判定部413とハンドオーバ情報保持部415を除く構成要素は、第1の実施形態と同じであるため、説明を簡略化又は省略する。
図17は、第4の実施形態の無線通信システムを構成する無線通信装置SNE4のブロック図である。図17では、図5に示した第1の実施形態の無線通信装置SNE1と共通する構成要素には、同じ参照符号が付されている。図17に示すように、第4の実施形態の無線通信装置SNE4は、無線受信部121と、ネットワーク用受信部123と、ネットワーク用送信部125と、無線送信部127と、制御部429とを備える。制御部429は、条件付きハンドオーバ判定部431と、ハンドオーバ要求部133とを有する。本実施形態では、制御部429の条件付きハンドオーバ判定部431を除く構成要素は、第1の実施形態と同じであるため、説明を簡略化又は省略する。
101 受信部
103,203,303,403 制御部
105 送信部
111 測定部
113,313,413 ハンドオーバ判定部
115,415 ハンドオーバ情報保持部
117 ハンドオーバ処理部
219 ハンドオーバ開始メッセージ作成部
SNE1,SNE2,SNE3,SNE4 無線通信装置
121,221 無線受信部
123 ネットワーク用受信部
125 ネットワーク用送信部
127 無線送信部
129,229,329,429 制御部
131,431 条件付きハンドオーバ判定部
133 ハンドオーバ要求部
335 ハンドオーバ開始判定部
TNE 無線通信装置
141 無線受信部
143 ネットワーク用受信部
145 ネットワーク用送信部
147 無線送信部
149 制御部
151 条件付きハンドオーバコマンド作成部
Claims (27)
- 制御チャネル及びデータチャネルを用いて無線通信装置と通信する無線通信端末が行うハンドオーバ制御方法であって、
当該無線通信端末が接続している自セルを提供する無線通信装置から送信された、所定の条件を満たせば隣接セルへのハンドオーバを開始するよう指示する条件付きハンドオーバコマンドを受信し、
前記所定の条件を満足するか否かを判定し、
前記所定の条件を満たせば、前記条件付きハンドオーバコマンドが示す前記隣接セルへのハンドオーバを開始するハンドオーバ制御方法。 - 請求項1に記載のハンドオーバ制御方法であって、
前記所定の条件は、前記無線通信端末により測定された、前記隣接セルにおけるデータチャネルの信号の受信品質が、前記自セルにおけるデータチャネルの信号の受信品質よりも良いことであるハンドオーバ制御方法。 - 請求項1に記載のハンドオーバ制御方法であって、
前記所定の条件は、前記自セルにおける制御チャネルの信号の前記無線通信端末により測定された受信品質が所定の閾値よりも低いことであるハンドオーバ制御方法。 - 請求項1に記載のハンドオーバ制御方法であって、
前記所定の条件は、前記無線通信端末により測定された、前記隣接セルにおけるデータチャネルの信号の受信品質が、前記自セルにおけるデータチャネルの信号の受信品質よりも良いこと、又は、前記自セルにおける制御チャネルの信号の受信品質が所定の閾値よりも低いことであるハンドオーバ制御方法。 - 請求項2~4のいずれか一項に記載のハンドオーバ制御方法であって、
前記所定の条件には、前記条件付きハンドオーバコマンドの受信からの経過時間が、前記条件付きハンドオーバコマンドが示す制限時間に到達することが選択的に含まれるハンドオーバ制御方法。 - 請求項1~5のいずれか一項に記載のハンドオーバ制御方法であって、
前記自セルは複数の無線通信装置によって提供されるハンドオーバ制御方法。 - 請求項1~5のいずれか一項に記載のハンドオーバ制御方法であって、
前記自セルは複数の無線通信装置によって提供され、前記無線通信端末は前記複数の無線通信装置のうち小セルを構成する無線通信装置に接続されており、前記隣接セルは、前記小セルよりもカバレッジの大きなマクロセルであるハンドオーバ制御方法。 - 請求項1~5のいずれか一項に記載のハンドオーバ制御方法であって、
前記自セルを提供する無線通信装置が備えるアンテナの本数は、前記隣接セルを提供する無線通信装置が備えるアンテナの本数よりも多いハンドオーバ制御方法。 - 請求項1~8のいずれか一項に記載のハンドオーバ制御方法であって、
前記所定の条件を満たしたとき、前記自セルを提供する無線通信装置に、前記隣接セルへのハンドオーバを開始することを示すメッセージを送信するハンドオーバ制御方法。 - 請求項1~9のいずれか一項に記載のハンドオーバ制御方法であって、
前記所定の条件を満たす前、前記自セルを提供する無線通信装置からハンドオーバを開始するよう指示するメッセージを受信すると、前記条件付きハンドオーバコマンドが示す前記隣接セルへのハンドオーバを開始するハンドオーバ制御方法。 - 請求項1~10のいずれか一項に記載のハンドオーバ制御方法であって、
前記所定の条件とは異なる条件又は異なる隣接セルへのハンドオーバを示す新たな条件付きハンドオーバコマンドを受信し、
前記新たな条件付きハンドオーバコマンドが示す条件を満たすか否かを判定し、
前記新たな条件付きハンドオーバコマンドが示す条件を満たせば、前記新たな条件付きハンドオーバコマンドが示す隣接セルへのハンドオーバを開始するハンドオーバ制御方法。 - 制御チャネル及びデータチャネルを用いて無線通信装置と通信する無線通信端末であって、
当該無線通信端末が接続している自セルを提供する無線通信装置から送信された、所定の条件を満たせば隣接セルへのハンドオーバを開始するよう指示する条件付きハンドオーバコマンドを受信する受信部と、
前記所定の条件を満足するか否かを判定するハンドオーバ判定部と、
前記所定の条件を満たせば、前記条件付きハンドオーバコマンドが示す前記隣接セルへのハンドオーバを開始するハンドオーバ処理部と、
を備えた無線通信端末。 - 請求項12に記載の無線通信端末であって、
前記所定の条件は、当該無線通信端末により測定された、前記隣接セルにおけるデータチャネルの信号の受信品質が、前記自セルにおけるデータチャネルの信号の受信品質よりも良いことである無線通信端末。 - 請求項12に記載の無線通信端末であって、
前記所定の条件は、前記自セルにおける制御チャネルの信号の当該無線通信端末により測定された受信品質が所定の閾値よりも低いことである無線通信端末。 - 請求項12に記載の無線通信端末であって、
前記所定の条件は、当該無線通信端末により測定された、前記隣接セルにおけるデータチャネルの信号の受信品質が、前記自セルにおけるデータチャネルの信号の受信品質よりも良いこと、又は、前記自セルにおける制御チャネルの信号の受信品質が所定の閾値よりも低いことである無線通信端末。 - 請求項13~15のいずれか一項に記載の無線通信端末であって、
前記所定の条件には、前記条件付きハンドオーバコマンドの受信からの経過時間が、前記条件付きハンドオーバコマンドが示す制限時間に到達することが選択的に含まれる無線通信端末。 - 請求項12~16のいずれか一項に記載の無線通信端末であって、
前記自セルは複数の無線通信装置によって提供される無線通信端末。 - 請求項12~16のいずれか一項に記載の無線通信端末であって、
前記自セルは複数の無線通信装置によって提供され、当該無線通信端末は前記複数の無線通信装置のうち小セルを構成する無線通信装置に接続されており、前記隣接セルは、前記小セルよりもカバレッジの大きなマクロセルである無線通信端末。 - 請求項12~16のいずれか一項に記載の無線通信端末であって、
前記自セルを提供する無線通信装置が備えるアンテナの本数は、前記隣接セルを提供する無線通信装置が備えるアンテナの本数よりも多い無線通信端末。 - 請求項12~19のいずれか一項に記載の無線通信端末であって、
前記所定の条件を満たしたとき、前記自セルを提供する無線通信装置に、前記隣接セルへのハンドオーバを開始することを示すメッセージを送信する無線通信端末。 - 請求項12~20のいずれか一項に記載の無線通信端末であって、
前記所定の条件を満たす前、前記自セルを提供する無線通信装置からハンドオーバを開始するよう指示するメッセージを受信すると、前記条件付きハンドオーバコマンドが示す前記隣接セルへのハンドオーバを開始する無線通信端末。 - 請求項12~21のいずれか一項に記載の無線通信端末であって、
前記所定の条件とは異なる条件又は異なる隣接セルへのハンドオーバを示す新たな条件付きハンドオーバコマンドを受信し、
前記新たな条件付きハンドオーバコマンドが示す条件を満たすか否かを判定し、
前記新たな条件付きハンドオーバコマンドが示す条件を満たせば、前記新たな条件付きハンドオーバコマンドが示す隣接セルへのハンドオーバを開始する無線通信端末。 - 制御チャネル及びデータチャネルを用いて無線通信端末と通信し、当該無線通信端末が接続している自セルを提供する無線通信装置であって、
前記無線通信端末から送信された情報又は当該無線通信装置が前記無線通信端末に提供している環境に基づいて、前記無線通信端末がハンドオーバする先の隣接セルを決定し、前記無線通信端末が行うハンドオーバとして、所定の条件を満たせば隣接セルへのハンドオーバを開始するよう指示するハンドオーバを開始する条件付きハンドオーバ又は条件が不要なハンドオーバのいずれかを選択する条件付きハンドオーバ判定部と、
所定の条件を満たせば前記隣接セルへのハンドオーバを開始する条件付きハンドオーバコマンドを前記無線通信端末に送信する無線送信部と、
前記無線通信端末がハンドオーバを開始したことを検知すると、前記隣接セルを提供する無線通信装置に前記無線通信端末宛のデータを転送するネットワーク用送信部と、
を備えた無線通信装置。 - 請求項23に記載の無線通信装置であって、
前記無線通信端末から送信された、前記無線通信端末がハンドオーバを開始することを示すメッセージを受信する無線受信部を備えた無線通信装置。 - 請求項23又は24に記載の無線通信装置であって、
前記所定の条件を満たす前、前記条件付きハンドオーバコマンドを送信した前記無線通信端末に、ハンドオーバを開始するよう指示するメッセージを作成するハンドオーバ開始メッセージ作成部を備え、
前記無線送信部は、前記ハンドオーバ開始メッセージ作成部が作成したメッセージを前記無線通信端末に送信する無線通信装置。 - 請求項23~25のいずれか一項に記載の無線通信装置であって、
前記無線送信部は、前記条件付きハンドオーバ判定部による決定内容に変更があった場合、又は、前記所定の条件に変更があった場合、当該変更内容を反映した条件付きハンドオーバコマンドを前記無線通信端末に送信する無線通信装置。 - 制御チャネル及びデータチャネルを用いて無線通信端末と通信可能であって、当該無線通信端末が接続している自セルに隣接したセルを提供する無線通信装置であって、
前記自セルを提供する無線通信装置から送信されたハンドオーバ要求メッセージを受信するネットワーク用受信部と、
前記ハンドオーバ要求メッセージに基づいて、所定の条件を満たせば隣接セルへのハンドオーバを開始するよう指示する条件付きハンドオーバコマンド又は条件が不要なハンドオーバコマンドのいずれかを作成するコマンド作成部と、
前記コマンド作成部が作成した前記条件付きハンドオーバコマンド又は前記ハンドオーバコマンドを含むハンドオーバ応答メッセージを、前記自セルを提供する無線通信装置に送信するネットワーク用送信部と、を備え、
前記コマンド作成部は、前記条件付きハンドオーバコマンドを作成する際、前記無線通信端末に提供する環境基づいて、前記所定の条件を決定する無線通信装置。
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US20140126545A1 (en) | 2014-05-08 |
US9591545B2 (en) | 2017-03-07 |
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