WO2018207297A1 - Base station apparatus, terminal apparatus, transmission interval control method, and wireless communication system - Google Patents

Base station apparatus, terminal apparatus, transmission interval control method, and wireless communication system Download PDF

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Publication number
WO2018207297A1
WO2018207297A1 PCT/JP2017/017760 JP2017017760W WO2018207297A1 WO 2018207297 A1 WO2018207297 A1 WO 2018207297A1 JP 2017017760 W JP2017017760 W JP 2017017760W WO 2018207297 A1 WO2018207297 A1 WO 2018207297A1
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WO
WIPO (PCT)
Prior art keywords
base station
terminal device
transmission interval
unit
control information
Prior art date
Application number
PCT/JP2017/017760
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French (fr)
Japanese (ja)
Inventor
武志 芥川
大出　高義
Original Assignee
富士通株式会社
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Publication date
Application filed by 富士通株式会社 filed Critical 富士通株式会社
Priority to PCT/JP2017/017760 priority Critical patent/WO2018207297A1/en
Publication of WO2018207297A1 publication Critical patent/WO2018207297A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/28—Cell structures using beam steering
    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/12—Wireless traffic scheduling

Definitions

  • the present invention relates to a base station device, a terminal device, a transmission interval control method, and a wireless communication system.
  • 5G 5th generation mobile communication
  • 5G 5th generation mobile communication
  • V2X (Vehicle to X) communication is one of 5G wireless communication operation cases.
  • V2X communication is V2V (Vehicle to Vehicle) communication, V2I (Vehicle to Infrastructure) communication, V2P (Vehicle to Pedestrian) communication and V2N (Vehicle to Network) vehicle.
  • V2V Vehicle to Vehicle
  • V2I Vehicle to Infrastructure
  • V2P Vehicle to Pedestrian
  • V2N (Vehicle to Network) vehicle This is a generic term for communication with a network. For example, a car traveling on a road communicates with surrounding cars, pedestrians or road signs.
  • a plurality of base station devices are arranged along a road, and a terminal device mounted on a running vehicle performs wireless communication with the base station device while sequentially repeating handover.
  • a terminal device mounted on a running vehicle performs wireless communication with the base station device while sequentially repeating handover.
  • a plurality of base station apparatuses arranged along the road may include, for example, an array antenna and form a directional beam in a predetermined direction. That is, for example, each base station apparatus may form a directional beam with a large gain in the direction of the road.
  • each base station apparatus estimates the direction of each car and forms a directional beam so as to follow the movement of the car.
  • a base station apparatus that forms a directional beam in a fixed direction (hereinafter referred to as “fixed beam”) and a base station apparatus that forms a directional beam (hereinafter referred to as “following beam”) that follows the movement of the vehicle.
  • fixed beam a base station apparatus that forms a directional beam in a fixed direction
  • following beam a base station apparatus that forms a directional beam that follows the movement of the vehicle.
  • the base station device that forms the tracking beam receives a signal transmitted from a terminal device mounted on the vehicle, and estimates the position of the vehicle by estimating the arrival direction of this signal.
  • the base station apparatus that forms a fixed beam forms a directional beam in a fixed direction, for example, on the road side, so there is no need to estimate the position of the vehicle. Therefore, when a vehicle moves from a cell of a base station device that forms a fixed beam to a cell of a base station device that forms a tracking beam, if the frequency of signal transmission by the terminal device is low, the destination base station device is accurate. It is difficult to form a simple tracking beam. As a result, during handover in which the terminal device moves between cells, a directional beam with sufficient gain is not directed toward the terminal device, which may cause a temporary decrease in transmission speed or communication interruption. There is sex.
  • V2X communication information for controlling the operation of the vehicle may be transmitted and received, so a decrease in communication quality such as a decrease in transmission speed or occurrence of communication interruption may cause a serious accident.
  • the disclosed technology has been made in view of the above points, and an object thereof is to provide a base station device, a terminal device, a transmission interval control method, and a wireless communication system that can suppress a decrease in communication quality. .
  • the base station device disclosed in the present application is, in one aspect, an acquisition unit that acquires control information related to a moving speed of a terminal device, and the terminal device transmits a connection destination from the first base station device to the second base station device.
  • a control unit for controlling the transmission interval of known signals by the terminal device, and transmission for transmitting control information on the transmission interval controlled by the control unit Part.
  • the base station device the terminal device, the transmission interval control method, and the wireless communication system disclosed in the present application, it is possible to suppress the deterioration of the communication quality.
  • FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to an embodiment.
  • FIG. 2 is a block diagram illustrating a configuration of a source base station according to an embodiment.
  • FIG. 3 is a block diagram illustrating a configuration of a target base station according to an embodiment.
  • FIG. 4 is a block diagram illustrating a configuration of the terminal device according to the embodiment.
  • FIG. 5 is a flowchart showing the operation of the source base station according to the embodiment.
  • FIG. 6 is a flowchart showing the operation of the target base station according to the embodiment.
  • FIG. 7 is a sequence diagram illustrating a transmission interval control process according to an embodiment.
  • FIG. 8 is a sequence diagram illustrating another transmission interval control process according to the embodiment.
  • FIG. 9 is a block diagram illustrating a hardware configuration example of the base station apparatus.
  • FIG. 10 is a block diagram illustrating a hardware configuration example of the terminal device.
  • FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to an embodiment.
  • the radio communication system shown in FIG. 1 includes base station apparatuses 100 and 200 and a terminal apparatus 300 mounted on a car.
  • base station apparatuses 100 and 200 includes base station apparatuses 100 and 200 and a terminal apparatus 300 mounted on a car.
  • terminal devices mounted on a plurality of vehicles may wirelessly communicate with base station devices 100 and 200.
  • the base station devices 100 and 200 are arranged along a road, for example, and perform wireless communication with a terminal device 300 mounted on a car traveling on the road. At this time, the base station apparatuses 100 and 200 form a fixed beam that faces the direction of the road, or form a tracking beam that follows the movement of the terminal apparatus 300. Specifically, the base station devices 100 and 200 form a fixed beam when, for example, the number of vehicles existing on the road in the cell of the own device is equal to or greater than a predetermined number, and exist on the road in the cell of the own device. When the number of cars to be operated is less than a predetermined number, a tracking beam is formed.
  • the base station apparatuses 100 and 200 When forming the tracking beam, the base station apparatuses 100 and 200 receive the pilot signal transmitted by the terminal apparatus 300 and estimate the arrival direction of the pilot signal. Then, base station apparatuses 100 and 200 form a tracking beam by forming a directional beam with a large gain in the estimated arrival direction. In order for the tracking beam to accurately follow the movement of the terminal device 300, the terminal device 300 needs to transmit a pilot signal at an appropriate transmission interval. Therefore, base station apparatuses 100 and 200 control the transmission interval of pilot signals transmitted by terminal apparatus 300 according to the moving speed of terminal apparatus 300 when terminal apparatus 300 is handed over.
  • the base station apparatus 100 that is the handover source with which the terminal apparatus 300 is communicating is referred to as the source base station 100
  • the base station apparatus 200 that is the handover destination of the terminal apparatus 300 is referred to as the target base station 200.
  • the terminal device 300 is a communication terminal mounted on a moving vehicle such as a car, and performs wireless communication with the base station devices 100 and 200 arranged along the road.
  • the terminal device 300 receives control information for controlling the transmission interval of the pilot signal from the source base station 100, and transmits the pilot signal according to the control information. Control the interval.
  • FIG. 2 is a block diagram illustrating a configuration of the source base station 100 according to an embodiment.
  • the base station apparatuses 100 and 200 have the same configuration regardless of whether they are source base stations or target base stations, but FIG. 2 shows the configuration as a source base station. The illustration of this configuration is omitted.
  • a transmission processing unit 101 includes a transmission processing unit 101, a reception processing unit 102, a beam control unit 103, a phase control unit 104, a channel quality measurement request unit 105, a channel quality information acquisition unit 106, a channel quality determination unit 107, It has a speed information request unit 108, a handover instruction (hereinafter abbreviated as “HO instruction”) unit 109, a speed information transfer unit 110, and a control information transfer unit 111.
  • HO instruction handover instruction
  • the transmission processing unit 101 performs transmission processing on a transmission signal transmitted to the terminal device 300. Specifically, the transmission processing unit 101 performs D / A conversion, up-conversion, and the like of the transmission signal, and transmits it to the terminal device 300 via the antenna.
  • the transmission signal subjected to transmission processing by the transmission processing unit 101 includes a line quality measurement request, a speed information request, a HO instruction, control information, and the like which will be described later.
  • the reception processing unit 102 performs reception processing on the received signal transmitted from the terminal device 300 and received via the antenna. Specifically, the reception processing unit 102 performs down-conversion and A / D conversion of the received signal.
  • the reception signal to which the reception processing unit 102 performs reception processing includes line quality information, speed information, a pilot signal, and the like which will be described later.
  • the beam control unit 103 calculates a phase for each antenna element for forming a fixed beam or a tracking beam, and sets the calculated phase in the phase control unit 104. That is, when the source base station 100 is a base station apparatus that forms a fixed beam, the beam control unit 103 calculates the phase for each antenna element according to the direction in which the fixed beam is formed, and sends it to the phase control unit 104. Set. In addition, when the source base station 100 is a base station apparatus that forms a tracking beam, the beam control unit 103 acquires the pilot signal received by the reception processing unit 102 and estimates the arrival direction of the pilot signal. Thus, the position of the terminal device 300 is estimated. Then, the beam control unit 103 calculates a phase for each antenna element according to the estimated position of the terminal device 300 and sets the phase control unit 104.
  • the phase control unit 104 forms a fixed beam or a tracking beam by applying the phase rotation set by the beam control unit 103 to the signal of each antenna element.
  • the channel quality measurement request unit 105 transmits a channel quality measurement request for requesting measurement of downlink channel quality with surrounding base station devices to the terminal device 300 at a predetermined cycle. That is, the channel quality measurement request unit 105 determines the downlink channel quality from each base station device in order to determine whether or not the base station device to which the terminal device 300 can be handed over is around the source base station 100. A line quality measurement request for requesting measurement is transmitted to the terminal device 300 via the transmission processing unit 101.
  • the line quality information acquisition unit 106 acquires line quality information including a measurement result of the terminal device 300 measuring the line quality from the reception signal received and processed by the reception processing unit 102. That is, when the terminal device 300 receives the channel quality measurement request, the terminal device 300 measures the downlink channel quality from each base station device and transmits the channel quality information including the measurement result. The line quality information transmitted from the device 300 is acquired.
  • the line quality determination unit 107 determines whether the line quality measurement result included in the line quality information has reached a predetermined handover level (hereinafter abbreviated as “HO level”), and the line quality has reached the HO level. If there is a base station apparatus that is present, the terminal apparatus 300 is determined to be handed over to this base station apparatus. Further, when there is no base station apparatus whose channel quality has reached the HO level, the channel quality determination unit 107 sets the channel quality to a handover preparation level (hereinafter abbreviated as “HO preparation level”) that is lower than the HO level. It is determined whether or not it has been reached. That is, the channel quality determination unit 107 determines from the channel quality whether or not there is a base station device that is likely to be handed over soon even when there is no base station device that can be handed over.
  • HO level predetermined handover level
  • the speed information requesting unit 108 When there is a base station apparatus whose line quality has been determined to have reached the HO preparation level by the line quality determining unit 107, the speed information requesting unit 108 issues a speed information request for requesting information on the moving speed of the terminal apparatus 300. It transmits to the terminal device 300.
  • the channel quality of the downlink from the target base station 200 to the terminal device 300 reaches the HO preparation level and then reaches the HO level.
  • the HO instruction section 109 sends a HO instruction to instruct the handover to the base station apparatus to the terminal apparatus 300. Send. Also, the HO instruction unit 109 notifies the handover destination base station apparatus that the terminal apparatus 300 is to be handed over. That is, in the present embodiment, the HO instruction unit 109 notifies the target base station 200 that the terminal device 300 is to be handed over.
  • the speed information transfer unit 110 acquires speed information including the moving speed of the terminal device 300 from the reception signal received and processed by the reception processing unit 102, and transfers the speed information to the target base station 200. As described above, when the line quality of the target base station 200 reaches the HO preparation level, the speed information request unit 108 transmits the speed information request, so that the speed information transfer unit 110 reaches the HO preparation level. In this case, the speed information is received from the terminal device 300 and transferred to the target base station 200.
  • the control information transfer unit 111 receives the control information for controlling the transmission interval of the pilot signal by the terminal device 300 from the target base station 200 and transfers the control information to the terminal device 300 after the speed information transfer unit 110 transfers the speed information. Specifically, when the target base station 200 is a base station apparatus that forms a fixed beam, the control information transfer unit 111 sets control information for setting the transmission interval of pilot signals to a relatively long fixed interval after handover. Is transferred to the terminal device 300. On the other hand, when the target base station 200 is a base station apparatus that forms a tracking beam, control information for transmitting a pilot signal is transmitted to the terminal apparatus 300 at a transmission interval corresponding to the moving speed of the terminal apparatus 300 before the handover. . That is, when the target base station 200 forms a tracking beam, the control information transfer unit 111 transfers control information for transmitting pilot signals to the terminal device 300 at relatively short intervals according to the moving speed.
  • FIG. 3 is a block diagram showing a configuration of the target base station 200 according to the embodiment.
  • the base station apparatuses 100 and 200 have the same configuration regardless of whether they are source base stations or target base stations, but FIG. 3 shows the configuration as a target base station. The illustration of this configuration is omitted.
  • the target base station 200 illustrated in FIG. 3 includes a transmission processing unit 201, a reception processing unit 202, a beam control unit 203, a phase control unit 204, a speed information reception unit 205, a transmission interval control unit 206, and a control information transmission unit 207.
  • the transmission processing unit 201 performs transmission processing on a transmission signal transmitted to the terminal device 300. Specifically, the transmission processing unit 201 performs D / A conversion, up-conversion, and the like of the transmission signal, and transmits to the terminal device 300 via the antenna.
  • the transmission signal to which the transmission processing unit 201 performs transmission processing includes a signal for the terminal device 300 to establish a connection with the target base station 200 at the time of handover.
  • the reception processing unit 202 performs reception processing on the received signal transmitted from the terminal device 300 and received via the antenna. Specifically, the reception processing unit 202 performs down-conversion and A / D conversion of the received signal.
  • the reception signal to which the reception processing unit 202 performs reception processing includes a pilot signal transmitted from the terminal device 300 and the like.
  • the beam control unit 203 calculates a phase for each antenna element for forming a fixed beam or a tracking beam, and sets the calculated phase in the phase control unit 204. That is, when the target base station 200 is a base station apparatus that forms a fixed beam, the beam control unit 203 calculates the phase for each antenna element according to the direction in which the fixed beam is formed, and sends it to the phase control unit 204. Set. In addition, when the target base station 200 is a base station apparatus that forms a tracking beam, the beam control unit 203 acquires the pilot signal received by the reception processing unit 202 and estimates the arrival direction of the pilot signal. Thus, the position of the terminal device 300 is estimated.
  • the beam control unit 203 calculates a phase for each antenna element according to the estimated position direction of the terminal device 300 and sets the calculated phase in the phase control unit 204.
  • the beam control unit 203 receives a notification of the transmission interval of the pilot signal from the terminal device 300 from the transmission interval control unit 206, and executes the arrival direction estimation using the pilot signal transmitted at this transmission interval.
  • the phase control unit 204 forms a fixed beam or a tracking beam by applying the phase rotation set by the beam control unit 203 to the signal of each antenna element.
  • the speed information receiving unit 205 receives the speed information transferred from the speed information transferring unit 110 of the source base station 100.
  • This speed information includes the moving speed of the terminal device 300 when the channel quality of the target base station 200 in the terminal device 300 reaches the HO preparation level.
  • the transmission interval control unit 206 determines whether the target base station 200 is a base station device that forms a fixed beam or a base station device that forms a tracking beam, and determines a transmission interval of pilot signals by the terminal device 300. . Specifically, when the target base station 200 is a base station apparatus that forms a fixed beam, the transmission interval control unit 206 sets the pilot signal transmission interval to a relatively long interval such as once per slot. Then decide.
  • the transmission interval control unit 206 determines a transmission interval according to the moving speed of the terminal device 300 based on the speed information. For example, the transmission interval control unit 206 may determine that the transmission interval of the pilot signal is x times per slot when the moving speed of the terminal device 300 is xkm / hour. However, when the target base station 200 forms a tracking beam, the transmission interval control unit 206 determines a shorter transmission interval than when a fixed beam is formed. That is, the transmission interval control unit 206 determines the transmission interval so that the pilot signal is transmitted from the terminal device 300 more frequently when the target base station 200 forms a tracking beam than when a fixed beam is formed. .
  • the control information transmission unit 207 transmits control information for notifying the terminal device 300 of the transmission interval of the pilot signal determined by the transmission interval control unit 206 to the terminal device 300 via the source base station 100. Specifically, when the target base station 200 forms a fixed beam, the control information transmission unit 207 transmits a pilot signal to the terminal device 300 after performing handover and releasing the connection with the source base station 100. Control information for changing the interval is transmitted. On the other hand, when the target base station 200 forms a follow-up beam, the control information transmission unit 207 transmits control information indicating that the terminal device 300 changes the transmission interval of the pilot signal from the current time before the handover.
  • control information transmission unit 207 transmits control information that makes the pilot signal transmission interval relatively long after handover, and the target base station 200 forms a tracking beam. In this case, control information for relatively shortening the pilot signal transmission interval is transmitted before the handover.
  • FIG. 4 is a block diagram illustrating a configuration of the terminal device 300 according to an embodiment. 4 includes a reception processing unit 301, a transmission processing unit 302, a line quality measurement unit 303, a speed information generation unit 304, a control information acquisition unit 305, a pilot signal generation unit 306, and a transmission interval control unit 307. .
  • the reception processing unit 301 performs reception processing on the received signal transmitted from the source base station 100 and received via the antenna. Specifically, the reception processing unit 301 performs down-conversion and A / D conversion of the received signal.
  • the reception signal subjected to reception processing by the reception processing unit 301 includes a line quality measurement request, a speed information request, control information, and the like.
  • the transmission processing unit 302 performs transmission processing on a transmission signal transmitted to the source base station 100 or the target base station 200. Specifically, the transmission processing unit 302 performs D / A conversion, up-conversion, and the like of the transmission signal and transmits it via the antenna.
  • the transmission signal to which the transmission processing unit 302 performs transmission processing includes line quality information, speed information, a pilot signal, and the like.
  • the channel quality measurement unit 303 When the channel quality measurement unit 303 receives the channel quality measurement request transmitted from the source base station 100, the channel quality measurement unit 303 determines the channel quality of the downlink between the peripheral base station apparatus including the target base station 200 and the terminal apparatus 300. taking measurement. Then, the line quality measuring unit 303 generates line quality information including the line quality of each base station apparatus, and transmits the line quality information to the source base station 100 via the transmission processing unit 302.
  • the speed information generation unit 304 acquires the moving speed of the terminal device 300 and generates speed information including the moving speed information.
  • the speed information generation unit 304 may acquire a moving speed from a speedometer of a vehicle on which the terminal device 300 is mounted, or may measure a Doppler frequency to acquire a moving speed. Further, the speed information generation unit 304 may acquire the moving speed by acquiring the position coordinates of the vehicle using, for example, GPS (Global Positioning System) and calculating the moving distance of the vehicle per unit time. Then, the speed information generation unit 304 transmits speed information including the moving speed of the terminal device 300 to the source base station 100 via the transmission processing unit 302.
  • GPS Global Positioning System
  • the control information acquisition unit 305 acquires the control information transmitted from the control information transmission unit 207 of the target base station 200 and transferred by the source base station 100.
  • This control information is information for instructing whether the pilot signal transmission interval and the pilot signal transmission interval should be changed before or after the handover.
  • Pilot signal generation section 306 generates a pilot signal that is a known signal and includes information that can identify terminal apparatus 300.
  • the pilot signal is used for the source base station 100 and the target base station 200 to estimate the position of the terminal device 300, and may be used for channel estimation of the uplink from the terminal device 300 to each base station device. .
  • the transmission interval control unit 307 controls the transmission interval of the pilot signal according to the control information acquired by the control information acquisition unit 305. Specifically, the transmission interval control unit 307 obtains the pilot signal after the handover to the target base station 200 is completed when control information instructing to make the transmission interval of the pilot signal relatively long after the handover is acquired. Adjust the transmission interval. In other words, the transmission interval control unit 307 maintains the current transmission interval during communication with the source base station 100, and after the connection with the source base station 100 is released, the transmission interval of the pilot signal is relatively long. To do. Thereby, even when the target base station 200 forms a fixed beam, the source base station 100 can form a tracking beam until the terminal device 300 is handed over.
  • the transmission interval control unit 307 acquires the pilot signal transmission interval before the handover to the target base station 200 when the control information instructing to relatively shorten the transmission interval of the pilot signal is acquired before the handover. Adjust. In other words, the transmission interval control unit 307 relatively shortens the transmission interval of the pilot signal immediately from the current point of communication with the source base station 100.
  • the target base station 200 forms a tracking beam
  • pilot signals are frequently transmitted before the terminal device 300 is handed over, and the target base station 200 estimates the position of the terminal device 300 in advance and transmits the tracking beam. Can be formed.
  • the channel quality measurement request unit 105 periodically transmits a channel quality measurement request to the terminal device 300 (step S101).
  • the terminal device 300 measures the channel quality of the surrounding base station devices including the target base station 200, and transmits the channel quality information.
  • the channel quality information is received by the source base station 100 (step S102) and acquired by the channel quality information acquisition unit 106. Then, the channel quality determination unit 107 determines whether there is a base station apparatus whose channel quality reaches the HO level (step S103). As a result of the determination, if there is a base station apparatus whose channel quality reaches the HO level (step S103 Yes), the HO instruction unit 109 instructs the corresponding base station apparatus and the terminal apparatus 300 to hand over the terminal apparatus 300. (Step S104).
  • Step S105 the line quality determination unit 107 continues to determine whether or not there is a base station apparatus whose line quality reaches the HO preparation level. That is, the channel quality of each base station apparatus is compared with an HO preparation level smaller than the HO level, and it is determined whether there is a base station apparatus that can be handed over by the terminal apparatus 300 soon. As a result of this determination, if there is no base station apparatus whose line quality reaches the HO preparation level (No in step S105), the terminal apparatus 300 continues communication with the source base station 100, so that a periodic line quality measurement request is made. Is repeated (step S101).
  • the speed information requesting unit 108 transmits a speed information request for requesting speed information to the terminal apparatus 300 (Step S105). S106). When the speed information is received from the terminal device 300 as a response to the speed information request, the speed information is transferred by the speed information transfer unit 110 to the base station apparatus (target base station 200) whose line quality has reached the HO preparation level. (Step S107).
  • the target base station 200 determines the transmission interval of the pilot signal by the terminal device 300 based on the speed information, and the control information indicating the transmission interval is sent to the source base station 100. Sent. This control information is received by the control information transfer unit 111 and transferred to the terminal device 300 via the transmission processing unit 101 (step S108). Thereby, the terminal device 300 can change the transmission interval of the pilot signal in advance before the handover to the target base station 200.
  • the periodic channel quality measurement request is repeated (step S101).
  • the HO instruction unit 109 causes the target base station 200 and the terminal device 300 to
  • the handover of the terminal device 300 is instructed (step S104).
  • the transmission interval of the pilot signal by the terminal apparatus 300 is changed in advance when the channel quality of the target base station 200 reaches the HO preparation level. Yes. For this reason, the target base station 200 can receive a pilot signal at a transmission interval sufficient to estimate the position of the terminal device 300, and can form a tracking beam.
  • step S201 When the channel quality of the target base station 200 in the terminal device 300 reaches the HO preparation level, speed information indicating the moving speed of the terminal device 300 is transmitted from the source base station 100 to the target base station 200.
  • the speed information is received by the speed information receiving unit 205 of the target base station 200 (step S201) and output to the transmission interval control unit 206.
  • the transmission interval control unit 206 determines whether the target base station 200 is a base station apparatus that forms a fixed beam or a base station apparatus that forms a tracking beam (step S202).
  • Whether the target base station 200 forms a fixed beam or a tracking beam may be set in advance, for example, may be adaptively set according to traffic conditions in the cell of the target base station 200, for example. .
  • a fixed beam is formed and exists on the road in the cell of the own device.
  • a tracking beam is formed.
  • the transmission interval control unit 206 determines that it is not necessary to follow the movement of the terminal device 300 by the transmission interval control unit 206. It is determined that position estimation is unnecessary. Therefore, the transmission interval control unit 206 determines that the transmission interval of the pilot signal by the terminal device 300 is a relatively long interval such as once per slot.
  • control information indicating that the transmission interval of the pilot signal is long is generated and transmitted from the control information transmitting unit 207 to the source base station 100 (step S205).
  • This control information is transferred from the source base station 100 to the terminal device 300, and the terminal device 300 sets the transmission interval of the pilot signal to a long interval after handover to the target base station 200 according to the control information.
  • a fixed beam is formed by the beam control unit 203 and the phase control unit 204 (step S206). Therefore, even if the transmission interval of the pilot signal by the terminal apparatus 300 is long, the communication quality at the time of handover There is no decline.
  • the terminal apparatus 300 since the terminal apparatus 300 does not change the transmission interval of the pilot signal until the handover is performed, when the source base station 100 forms a tracking beam, the terminal apparatus 300 transmits the pilot signal at a short interval before the handover. To do. As a result, the source base station 100 can estimate the position of the terminal device 300 and form a tracking beam until the terminal device 300 is handed over.
  • the transmission interval control unit 206 determines the transmission interval of the pilot signal based on the speed information (step S203). Specifically, for example, when the moving speed of the terminal device 300 is x km / h, it is determined that the transmission interval of the pilot signal is x times per slot. However, when the target base station 200 forms a tracking beam, it is determined that the transmission interval is shorter than when a fixed beam is formed.
  • control information indicating that the pilot signal transmission interval is set to a short interval before handover to the target base station 200 is generated and transmitted from the control information transmitting unit 207 to the source base station 100 (step S204).
  • This control information is transferred from the source base station 100 to the terminal device 300, and the terminal device 300 sets the transmission interval of the pilot signal to a short interval from the current point before the handover to the target base station 200 according to the control information.
  • a tracking beam is formed by the beam control unit 203 and the phase control unit 204 using a pilot signal transmitted at a short transmission interval (step S206).
  • the target base station 200 can estimate the position of the terminal device 300 before the terminal device 300 is handed over to form the tracking beam, It is possible to suppress a decrease in communication quality at the time of handover.
  • the operation when the source base station 100 forms a fixed beam and the target base station 200 forms a tracking beam will be specifically described with reference to the sequence diagram shown in FIG. .
  • a channel quality measurement request is periodically transmitted from the source base station 100 to the terminal device 300 (step S301).
  • the terminal device 300 measures the channel quality of the downlink from the surrounding base station devices including the target base station 200 (step S302). And the terminal device 300 transmits line quality information to the source base station 100 (step S303).
  • the channel quality information When the channel quality information is received by the source base station 100, it is determined whether or not there is a base station apparatus whose channel quality reaches the HO level or the HO preparation level. Here, description will be made assuming that the channel quality of the target base station 200 has reached the HO preparation level.
  • a speed information request is transmitted from the source base station 100 to the terminal device 300 (step S304), and speed information indicating the moving speed of the terminal device 300 is returned as a response. It is transmitted to the source base station 100 (step S305).
  • the speed information is transferred from the source base station 100 to the target base station 200 (step S306), and the target base station 200 determines the transmission interval of the pilot signal by the terminal device 300 based on the speed information (step S307). That is, since the target base station 200 is a base station apparatus that forms a follow-up beam, the target base station 200 determines the pilot signal transmission interval as a relatively short interval according to the moving speed of the terminal device 300. Then, control information indicating that the pilot signal transmission interval is short before handover is transmitted from the target base station 200 to the source base station 100 (step S308).
  • the control information is transferred from the source base station 100 to the terminal device 300 (step S309), and the terminal device 300 changes the transmission interval of the pilot signal to a short interval from the current time before the handover.
  • the target base station 200 estimates the position of the terminal device 300 using the pilot signal, and starts forming a follow-up beam that follows the movement of the terminal device 300 (step S310).
  • a channel quality measurement request is periodically transmitted from the source base station 100 to the terminal apparatus 300 (step S311).
  • the terminal device 300 measures the downlink channel quality from the surrounding base station devices including the target base station 200 (step S312). Then, the terminal device 300 transmits the line quality information to the source base station 100 (step S313).
  • the channel quality information When the channel quality information is received by the source base station 100, it is determined whether or not there is a base station apparatus whose channel quality reaches the HO level or the HO preparation level. Here, the description will proceed assuming that the channel quality of the target base station 200 has reached the HO level.
  • a handover instruction is transmitted from the source base station 100 to the terminal device 300 and the target base station 200 (steps S314 and S315), and the terminal device 300 is transmitted to the target base station 200.
  • a channel quality measurement request is periodically transmitted from the source base station 100 to the terminal device 300, and the channel quality information is returned from the terminal device 300 to the source base station 100.
  • Steps S301 to S303 When the channel quality of the target base station 200 reaches the HO preparation level, speed information indicating the moving speed of the terminal device 300 is transferred to the target base station 200 (steps S304 to S306).
  • the target base station 200 determines whether or not the own station is a base station apparatus that forms a tracking beam.
  • the target base station 200 forms a fixed beam. It is determined that it is a device. For this reason, it is determined that it is not necessary to form a tracking beam (step S401), and control information indicating that the transmission interval of the pilot signal is long after the handover to the target base station 200 is received from the target base station 200. It is transmitted to the source base station 100 (step S402). That is, since the target base station 200 forms a fixed beam, there is no need to estimate the position of the terminal device 300, and the transmission interval of pilot signals by the terminal device 300 may be a relatively long interval.
  • control information for changing the transmission interval of the pilot signal after the handover is transmitted to the source base station 100 and transferred to the terminal device 300 (step S403).
  • a channel quality measurement request is periodically transmitted from the source base station 100 to the terminal device 300, and the channel quality information is transmitted from the terminal device 300 to the source base station. 100 is returned (steps S311 to S313).
  • a handover instruction is transmitted from the source base station 100 to the terminal device 300 and the target base station 200 (steps S314 and S315), and the terminal device 300 A handover to the station 200 is executed.
  • the terminal device 300 performs handover to the target base station 200 and releases the connection with the source base station 100, and then adjusts the transmission interval of the pilot signal to a longer interval. (Step S404). For this reason, until the terminal device 300 is handed over, the source base station 100 can form a tracking beam, and communication quality does not deteriorate.
  • the speed information indicating the moving speed of the terminal device is transferred to the target base station that is the handover destination before the handover, and the transmission interval of the pilot signal by the terminal device is set according to the moving speed. It is determined.
  • the target base station forms a tracking beam
  • the terminal device transmits a pilot signal at a transmission interval corresponding to the moving speed, and the target base station forms the tracking beam using the pilot signal before the handover. To do. For this reason, when the terminal device performs a handover to the target base station, the communication speed does not decrease, the communication is not interrupted, and the deterioration of the communication quality can be suppressed.
  • the target base station 200 determines the transmission interval of the pilot signal by the terminal device 300 based on the speed information.
  • the transmission interval is determined by the source base station 100 or the terminal device. 300 may execute. In other words, as long as the device knows the moving speed of the terminal device 300 and whether or not the target base station 200 forms a tracking beam, even if a device other than the target base station 200 determines the transmission interval of the pilot signal. good.
  • the frequencies used by the source base station 100 and the target base station 200 for communication may be the same or different.
  • the terminal device 300 performs random access to the target base station 200 during communication with the source base station 100, and temporarily receives the two base stations. Communication may be performed simultaneously with the device.
  • the terminal device 300 performs simultaneous communication with the source base station 100 and the target base station 200 by carrier aggregation, and either one of the base stations.
  • the communication may be switched.
  • Such switching corresponds to a change of the cell used by the terminal device 300 for communication, and the same operation as that at the time of handover in the above embodiment is possible.
  • the terminal device 300 starts communication with the target base station 200 in addition to communication with the source base station 100.
  • the terminal device 300 controls the transmission interval of pilot signals as necessary.
  • the transmission interval of the pilot signal is controlled according to the moving speed of the terminal device 300.
  • the source base station 100 and the target base station 200 have a hardware configuration as shown in FIG. That is, the base station apparatus 10 including the source base station 100 and the target base station 200 includes a communication interface (hereinafter abbreviated as “communication I / F”) 11, a processor 12, a memory 13, and a wireless processing unit 14.
  • communication I / F a communication interface
  • processor 12 a processor 12, a memory 13, and a wireless processing unit 14.
  • the communication I / F 11 is an interface such as an X2 interface that communicates with other base station apparatuses, and transmits and receives speed information and control information. Therefore, the communication I / F 11 corresponds to the speed information transfer unit 110 and the control information transfer unit 111 of the source base station 100, and the speed information reception unit 205 and the control information transmission unit 207 of the target base station 200.
  • the processor 12 includes, for example, a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), and the like, and controls the entire base station apparatus 10.
  • the processor 12 corresponds to the beam control unit 103, the channel quality measurement request unit 105, the channel quality information acquisition unit 106, the channel quality determination unit 107, the speed information request unit 108, and the HO instruction unit 109 of the source base station 100.
  • the processor 12 corresponds to the beam control unit 203, the transmission interval control unit 206, and the HO control unit 208 of the target base station 200.
  • the memory 13 includes, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores various types of information when processing is executed by the processor 12.
  • a RAM Random Access Memory
  • ROM Read Only Memory
  • the wireless processing unit 14 performs wireless processing on a signal transmitted / received to / from the terminal device 300. That is, the wireless processing unit 14 transmits a line quality measurement request and a speed information request, and receives line quality information, speed information, and a pilot signal. Therefore, the radio processing unit 14 includes the transmission processing unit 101, the reception processing unit 102, and the phase control unit 104 of the source base station 100, and the transmission processing unit 201, the reception processing unit 202, and the phase control unit 204 of the target base station 200. Correspond.
  • the terminal device 300 has a hardware configuration as shown in FIG. 10, for example. That is, the terminal device 20 including the terminal device 300 includes the wireless processing unit 21, the processor 22, and the memory 23.
  • the radio processing unit 21 performs radio processing on a signal transmitted / received between the source base station 100 and the target base station 200. That is, the wireless processing unit 21 transmits line quality information, speed information, pilot signals, and the like, and receives a line quality measurement request and a speed information request. Therefore, the wireless processing unit 21 corresponds to the reception processing unit 301 and the transmission processing unit 302 of the terminal device 300.
  • the processor 22 includes, for example, a CPU, FPGA, or DSP, and controls the terminal device 20 as a whole.
  • the processor 22 corresponds to the line quality measurement unit 303, the speed information generation unit 304, the control information acquisition unit 305, the pilot signal generation unit 306, and the transmission interval control unit 307 of the terminal device 300.
  • the memory 23 includes, for example, a RAM or a ROM, and stores various information when processing is executed by the processor 22.

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Abstract

A base station apparatus comprises: an acquisition unit (205) that acquires control information related to a movement speed of a terminal apparatus (300); a control unit (206) that, upon a change, by the terminal apparatus (300), of the connecting destination from a first base station apparatus (100) to a second base station apparatus (200), controls, on the basis of the control information acquired by the acquisition unit (205), the transmission interval of known signals transmitted by the terminal apparatus (300); and a transmission unit (207) that transmits control information related to the transmission interval as controlled by the control unit (206).

Description

基地局装置、端末装置、送信間隔制御方法及び無線通信システムBase station apparatus, terminal apparatus, transmission interval control method, and radio communication system
　本発明は、基地局装置、端末装置、送信間隔制御方法及び無線通信システムに関する。 The present invention relates to a base station device, a terminal device, a transmission interval control method, and a wireless communication system.
　近年、次世代の移動体通信システムの通信規格である５Ｇ（第５世代移動体通信）についての議論が活発化している。５Ｇが採用される移動体通信システムでは、高信頼性かつ低遅延の無線通信の実現が見込まれるため、様々な分野で無線通信が利用されると考えられる。 In recent years, discussions about 5G (5th generation mobile communication), which is a communication standard for the next generation mobile communication system, have been activated. In a mobile communication system employing 5G, it is expected that wireless communication with high reliability and low delay will be realized. Therefore, wireless communication is considered to be used in various fields.
　５Ｇの無線通信の運用ケースの１つとして、Ｖ２Ｘ（Vehicle　to　X）通信がある。Ｖ２Ｘ通信とは、Ｖ２Ｖ（Vehicle　to　Vehicle：車対車）通信、Ｖ２Ｉ（Vehicle　to　Infrastructure：車対インフラストラクチャ）通信、Ｖ２Ｐ（Vehicle　to　Pedestrian：車対歩行者）通信及びＶ２Ｎ（Vehicle　to　Network：車対ネットワーク）通信の総称であり、例えば道路を走行中の車が周囲の車、歩行者又は道路標識などと通信するものである。 V2X (Vehicle to X) communication is one of 5G wireless communication operation cases. V2X communication is V2V (Vehicle to Vehicle) communication, V2I (Vehicle to Infrastructure) communication, V2P (Vehicle to Pedestrian) communication and V2N (Vehicle to Network) vehicle. This is a generic term for communication with a network. For example, a car traveling on a road communicates with surrounding cars, pedestrians or road signs.
　このようなＶ２Ｘ通信においては、道路に沿って複数の基地局装置が配置され、走行中の車に搭載された端末装置は、順次ハンドオーバを繰り返しながら、基地局装置との間で無線通信を行うことがある。 In such V2X communication, a plurality of base station devices are arranged along a road, and a terminal device mounted on a running vehicle performs wireless communication with the base station device while sequentially repeating handover. Sometimes.
特開２０１７－４１７４４号公報JP 2017-41744 A 特開２００９－２４６８６０号公報JP 2009-246860 A
　ところで、道路に沿って配置される複数の基地局装置は、例えばアレイアンテナを備え、所定の方向へ指向性ビームを形成することがある。すなわち、例えば各基地局装置が道路側の方向への利得が大きい指向性ビームを形成することがある。また、各基地局装置がそれぞれの車の方向を推定し、車の移動に追従するように指向性ビームを形成することなども検討されている。 By the way, a plurality of base station apparatuses arranged along the road may include, for example, an array antenna and form a directional beam in a predetermined direction. That is, for example, each base station apparatus may form a directional beam with a large gain in the direction of the road. In addition, it has been studied that each base station apparatus estimates the direction of each car and forms a directional beam so as to follow the movement of the car.
　しかしながら、例えば固定した方向への指向性ビーム（以下「固定ビーム」という）を形成する基地局装置と、車の移動に追従する指向性ビーム（以下「追従ビーム」という）を形成する基地局装置が混在する無線通信システムにおいては、通信断の恐れがあるという問題がある。 However, for example, a base station apparatus that forms a directional beam in a fixed direction (hereinafter referred to as “fixed beam”) and a base station apparatus that forms a directional beam (hereinafter referred to as “following beam”) that follows the movement of the vehicle. In a wireless communication system in which communication is mixed, there is a problem that communication may be interrupted.
　具体的には、追従ビームを形成する基地局装置は、車に搭載される端末装置から送信される信号を受信し、この信号の到来方向を推定することにより車の位置を推定する。これに対して、固定ビームを形成する基地局装置は、例えば道路側などの固定した方向へ指向性ビームを形成するため、車の位置を推定する必要がない。したがって、固定ビームを形成する基地局装置のセルから追従ビームを形成する基地局装置のセルへ車が移動する際に、端末装置による信号の送信頻度が低ければ、移動先の基地局装置が正確な追従ビームを形成することが困難である。この結果、端末装置がセル間を移動するハンドオーバの際には、十分な利得の指向性ビームが端末装置の方向へ向かないことになり、一時的な伝送速度の低下や通信断が発生する可能性がある。 Specifically, the base station device that forms the tracking beam receives a signal transmitted from a terminal device mounted on the vehicle, and estimates the position of the vehicle by estimating the arrival direction of this signal. On the other hand, the base station apparatus that forms a fixed beam forms a directional beam in a fixed direction, for example, on the road side, so there is no need to estimate the position of the vehicle. Therefore, when a vehicle moves from a cell of a base station device that forms a fixed beam to a cell of a base station device that forms a tracking beam, if the frequency of signal transmission by the terminal device is low, the destination base station device is accurate. It is difficult to form a simple tracking beam. As a result, during handover in which the terminal device moves between cells, a directional beam with sufficient gain is not directed toward the terminal device, which may cause a temporary decrease in transmission speed or communication interruption. There is sex.
　Ｖ２Ｘ通信では、車の動作を制御する情報などが送受信されることがあるため、伝送速度の低下や通信断の発生などの通信品質の低下は、重大な事故を引き起こす原因にもなり得る。 In V2X communication, information for controlling the operation of the vehicle may be transmitted and received, so a decrease in communication quality such as a decrease in transmission speed or occurrence of communication interruption may cause a serious accident.
　開示の技術は、かかる点に鑑みてなされたものであって、通信品質の低下を抑制することができる基地局装置、端末装置、送信間隔制御方法及び無線通信システムを提供することを目的とする。 The disclosed technology has been made in view of the above points, and an object thereof is to provide a base station device, a terminal device, a transmission interval control method, and a wireless communication system that can suppress a decrease in communication quality. .
　本願が開示する基地局装置は、１つの態様において、端末装置の移動速度に関する制御情報を取得する取得部と、前記端末装置が第１の基地局装置から第２の基地局装置へ接続先を変更する際に、前記取得部によって取得された制御情報に基づいて、前記端末装置による既知信号の送信間隔を制御する制御部と、前記制御部によって制御された送信間隔に関する制御情報を送信する送信部とを有する。 In one aspect, the base station device disclosed in the present application is, in one aspect, an acquisition unit that acquires control information related to a moving speed of a terminal device, and the terminal device transmits a connection destination from the first base station device to the second base station device. When changing, based on the control information acquired by the acquisition unit, a control unit for controlling the transmission interval of known signals by the terminal device, and transmission for transmitting control information on the transmission interval controlled by the control unit Part.
　本願が開示する基地局装置、端末装置、送信間隔制御方法及び無線通信システムの１つの態様によれば、通信品質の低下を抑制することができるという効果を奏する。 According to one aspect of the base station device, the terminal device, the transmission interval control method, and the wireless communication system disclosed in the present application, it is possible to suppress the deterioration of the communication quality.
図１は、一実施の形態に係る無線通信システムの構成を示す図である。FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to an embodiment. 図２は、一実施の形態に係るソース基地局の構成を示すブロック図である。FIG. 2 is a block diagram illustrating a configuration of a source base station according to an embodiment. 図３は、一実施の形態に係るターゲット基地局の構成を示すブロック図である。FIG. 3 is a block diagram illustrating a configuration of a target base station according to an embodiment. 図４は、一実施の形態に係る端末装置の構成を示すブロック図である。FIG. 4 is a block diagram illustrating a configuration of the terminal device according to the embodiment. 図５は、一実施の形態に係るソース基地局の動作を示すフロー図である。FIG. 5 is a flowchart showing the operation of the source base station according to the embodiment. 図６は、一実施の形態に係るターゲット基地局の動作を示すフロー図である。FIG. 6 is a flowchart showing the operation of the target base station according to the embodiment. 図７は、一実施の形態に係る送信間隔制御処理を示すシーケンス図である。FIG. 7 is a sequence diagram illustrating a transmission interval control process according to an embodiment. 図８は、一実施の形態に係る他の送信間隔制御処理を示すシーケンス図である。FIG. 8 is a sequence diagram illustrating another transmission interval control process according to the embodiment. 図９は、基地局装置のハードウェア構成例を示すブロック図である。FIG. 9 is a block diagram illustrating a hardware configuration example of the base station apparatus. 図１０は、端末装置のハードウェア構成例を示すブロック図である。FIG. 10 is a block diagram illustrating a hardware configuration example of the terminal device.
　以下、本願が開示する基地局装置、端末装置、送信間隔制御方法及び無線通信システムの一実施の形態について、図面を参照して詳細に説明する。なお、この実施の形態により本発明が限定されるものではない。 Hereinafter, an embodiment of a base station device, a terminal device, a transmission interval control method, and a wireless communication system disclosed in the present application will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.
　図１は、一実施の形態に係る無線通信システムの構成を示す図である。図１に示す無線通信システムは、基地局装置１００、２００と車に搭載された端末装置３００とを有する。なお、図１においては、端末装置３００を１つのみ図示しているが、複数の車にそれぞれ搭載された端末装置が基地局装置１００、２００と無線通信しても良い。 FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to an embodiment. The radio communication system shown in FIG. 1 includes base station apparatuses 100 and 200 and a terminal apparatus 300 mounted on a car. In FIG. 1, only one terminal device 300 is illustrated, but terminal devices mounted on a plurality of vehicles may wirelessly communicate with base station devices 100 and 200.
　基地局装置１００、２００は、例えば道路に沿って配置され、道路を走行する車に搭載された端末装置３００と無線通信を実行する。このとき、基地局装置１００、２００は、道路の方向を向く固定ビームを形成したり、端末装置３００の移動に追従する追従ビームを形成したりする。具体的には、基地局装置１００、２００は、例えば自装置のセル内の道路に存在する車の数が所定数以上の場合には固定ビームを形成し、自装置のセル内の道路に存在する車の数が所定数未満の場合には追従ビームを形成する。 The base station devices 100 and 200 are arranged along a road, for example, and perform wireless communication with a terminal device 300 mounted on a car traveling on the road. At this time, the base station apparatuses 100 and 200 form a fixed beam that faces the direction of the road, or form a tracking beam that follows the movement of the terminal apparatus 300. Specifically, the base station devices 100 and 200 form a fixed beam when, for example, the number of vehicles existing on the road in the cell of the own device is equal to or greater than a predetermined number, and exist on the road in the cell of the own device. When the number of cars to be operated is less than a predetermined number, a tracking beam is formed.
　基地局装置１００、２００は、追従ビームを形成する場合には、端末装置３００が送信するパイロット信号を受信し、パイロット信号の到来方向を推定する。そして、基地局装置１００、２００は、推定した到来方向への利得が大きい指向性ビームを形成することにより、追従ビームを形成する。追従ビームが端末装置３００の移動に正確に追従するためには、端末装置３００が適切な送信間隔でパイロット信号を送信する必要がある。そこで、基地局装置１００、２００は、端末装置３００がハンドオーバする際に、端末装置３００の移動速度に応じて端末装置３００が送信するパイロット信号の送信間隔を制御する。 When forming the tracking beam, the base station apparatuses 100 and 200 receive the pilot signal transmitted by the terminal apparatus 300 and estimate the arrival direction of the pilot signal. Then, base station apparatuses 100 and 200 form a tracking beam by forming a directional beam with a large gain in the estimated arrival direction. In order for the tracking beam to accurately follow the movement of the terminal device 300, the terminal device 300 needs to transmit a pilot signal at an appropriate transmission interval. Therefore, base station apparatuses 100 and 200 control the transmission interval of pilot signals transmitted by terminal apparatus 300 according to the moving speed of terminal apparatus 300 when terminal apparatus 300 is handed over.
　以下においては、端末装置３００が通信中のハンドオーバ元となる基地局装置１００をソース基地局１００といい、端末装置３００のハンドオーバ先となる基地局装置２００をターゲット基地局２００という。 Hereinafter, the base station apparatus 100 that is the handover source with which the terminal apparatus 300 is communicating is referred to as the source base station 100, and the base station apparatus 200 that is the handover destination of the terminal apparatus 300 is referred to as the target base station 200.
　端末装置３００は、車などの移動する車両に搭載された通信端末であり、道路沿いに配置された基地局装置１００、２００と無線通信を実行する。端末装置３００は、ソース基地局１００のセルからターゲット基地局２００のセルへハンドオーバする際に、パイロット信号の送信間隔を制御する制御情報をソース基地局１００から受信し、制御情報に従ってパイロット信号の送信間隔を制御する。 The terminal device 300 is a communication terminal mounted on a moving vehicle such as a car, and performs wireless communication with the base station devices 100 and 200 arranged along the road. When handing over from the cell of the source base station 100 to the cell of the target base station 200, the terminal device 300 receives control information for controlling the transmission interval of the pilot signal from the source base station 100, and transmits the pilot signal according to the control information. Control the interval.
　図２は、一実施の形態に係るソース基地局１００の構成を示すブロック図である。なお、基地局装置１００、２００は、ソース基地局であるかターゲット基地局であるかに関わらず同等の構成を有するが、図２においては、ソース基地局としての構成を図示しており、他の構成については図示を省略している。図２に示すソース基地局１００は、送信処理部１０１、受信処理部１０２、ビーム制御部１０３、位相制御部１０４、回線品質測定要求部１０５、回線品質情報取得部１０６、回線品質判定部１０７、速度情報要求部１０８、ハンドオーバ指示（以下「ＨＯ指示」と略記する）部１０９、速度情報転送部１１０及び制御情報転送部１１１を有する。 FIG. 2 is a block diagram illustrating a configuration of the source base station 100 according to an embodiment. The base station apparatuses 100 and 200 have the same configuration regardless of whether they are source base stations or target base stations, but FIG. 2 shows the configuration as a source base station. The illustration of this configuration is omitted. The source base station 100 shown in FIG. 2 includes a transmission processing unit 101, a reception processing unit 102, a beam control unit 103, a phase control unit 104, a channel quality measurement request unit 105, a channel quality information acquisition unit 106, a channel quality determination unit 107, It has a speed information request unit 108, a handover instruction (hereinafter abbreviated as “HO instruction”) unit 109, a speed information transfer unit 110, and a control information transfer unit 111.
　送信処理部１０１は、端末装置３００に対して送信する送信信号に送信処理を施す。具体的には、送信処理部１０１は、送信信号のＤ／Ａ変換及びアップコンバートなどを実行し、アンテナを介して端末装置３００へ送信する。送信処理部１０１が送信処理を施す送信信号には、後述する回線品質測定要求、速度情報要求、ＨＯ指示及び制御情報などが含まれる。 The transmission processing unit 101 performs transmission processing on a transmission signal transmitted to the terminal device 300. Specifically, the transmission processing unit 101 performs D / A conversion, up-conversion, and the like of the transmission signal, and transmits it to the terminal device 300 via the antenna. The transmission signal subjected to transmission processing by the transmission processing unit 101 includes a line quality measurement request, a speed information request, a HO instruction, control information, and the like which will be described later.
　受信処理部１０２は、端末装置３００が送信しアンテナを介して受信された受信信号に受信処理を施す。具体的には、受信処理部１０２は、受信信号のダウンコンバード及びＡ／Ｄ変換などを実行する。受信処理部１０２が受信処理を施す受信信号には、後述する回線品質情報、速度情報及びパイロット信号などが含まれる。 The reception processing unit 102 performs reception processing on the received signal transmitted from the terminal device 300 and received via the antenna. Specifically, the reception processing unit 102 performs down-conversion and A / D conversion of the received signal. The reception signal to which the reception processing unit 102 performs reception processing includes line quality information, speed information, a pilot signal, and the like which will be described later.
　ビーム制御部１０３は、固定ビーム又は追従ビームを形成するためのアンテナ素子ごとの位相を算出し、算出した位相を位相制御部１０４に設定する。すなわち、ビーム制御部１０３は、ソース基地局１００が固定ビームを形成する基地局装置である場合には、固定ビームを形成する方向に応じたアンテナ素子ごとの位相を算出して位相制御部１０４に設定する。また、ビーム制御部１０３は、ソース基地局１００が追従ビームを形成する基地局装置である場合には、受信処理部１０２によって受信処理されたパイロット信号を取得し、パイロット信号の到来方向を推定することにより、端末装置３００の位置を推定する。そして、ビーム制御部１０３は、推定した端末装置３００の位置の方向に応じたアンテナ素子ごとの位相を算出して位相制御部１０４に設定する。 The beam control unit 103 calculates a phase for each antenna element for forming a fixed beam or a tracking beam, and sets the calculated phase in the phase control unit 104. That is, when the source base station 100 is a base station apparatus that forms a fixed beam, the beam control unit 103 calculates the phase for each antenna element according to the direction in which the fixed beam is formed, and sends it to the phase control unit 104. Set. In addition, when the source base station 100 is a base station apparatus that forms a tracking beam, the beam control unit 103 acquires the pilot signal received by the reception processing unit 102 and estimates the arrival direction of the pilot signal. Thus, the position of the terminal device 300 is estimated. Then, the beam control unit 103 calculates a phase for each antenna element according to the estimated position of the terminal device 300 and sets the phase control unit 104.
　位相制御部１０４は、ビーム制御部１０３によって設定された位相回転をアンテナ素子それぞれの信号に付与することにより、固定ビーム又は追従ビームを形成する。 The phase control unit 104 forms a fixed beam or a tracking beam by applying the phase rotation set by the beam control unit 103 to the signal of each antenna element.
　回線品質測定要求部１０５は、周囲の基地局装置との間の下り回線の回線品質の測定を要求する回線品質測定要求を所定の周期で端末装置３００へ送信する。すなわち、回線品質測定要求部１０５は、端末装置３００がハンドオーバ可能な基地局装置がソース基地局１００の周囲にあるか否かを判定するために、各基地局装置からの下り回線の回線品質を測定するように要求する回線品質測定要求を送信処理部１０１を介して端末装置３００へ送信する。 The channel quality measurement request unit 105 transmits a channel quality measurement request for requesting measurement of downlink channel quality with surrounding base station devices to the terminal device 300 at a predetermined cycle. That is, the channel quality measurement request unit 105 determines the downlink channel quality from each base station device in order to determine whether or not the base station device to which the terminal device 300 can be handed over is around the source base station 100. A line quality measurement request for requesting measurement is transmitted to the terminal device 300 via the transmission processing unit 101.
　回線品質情報取得部１０６は、受信処理部１０２によって受信処理される受信信号から、端末装置３００が回線品質を測定した測定結果を含む回線品質情報を取得する。すなわち、端末装置３００は、回線品質測定要求を受信すると各基地局装置からの下り回線の回線品質を測定し、測定結果を含む回線品質情報を送信するため、回線品質情報取得部１０６は、端末装置３００から送信された回線品質情報を取得する。 The line quality information acquisition unit 106 acquires line quality information including a measurement result of the terminal device 300 measuring the line quality from the reception signal received and processed by the reception processing unit 102. That is, when the terminal device 300 receives the channel quality measurement request, the terminal device 300 measures the downlink channel quality from each base station device and transmits the channel quality information including the measurement result. The line quality information transmitted from the device 300 is acquired.
　回線品質判定部１０７は、回線品質情報に含まれる回線品質の測定結果が所定のハンドオーバレベル（以下「ＨＯレベル」と略記する）に達しているか否かを判定し、回線品質がＨＯレベルに達している基地局装置がある場合には、この基地局装置へ端末装置３００をハンドオーバさせると決定する。また、回線品質判定部１０７は、回線品質がＨＯレベルに達している基地局装置がない場合には、回線品質がＨＯレベルよりも小さいハンドオーバ準備レベル（以下「ＨＯ準備レベル」と略記する）に達しているか否かを判定する。すなわち、回線品質判定部１０７は、ハンドオーバ可能な基地局装置がない場合でも、間もなくハンドオーバが可能になりそうな基地局装置があるか否かを回線品質から判定する。 The line quality determination unit 107 determines whether the line quality measurement result included in the line quality information has reached a predetermined handover level (hereinafter abbreviated as “HO level”), and the line quality has reached the HO level. If there is a base station apparatus that is present, the terminal apparatus 300 is determined to be handed over to this base station apparatus. Further, when there is no base station apparatus whose channel quality has reached the HO level, the channel quality determination unit 107 sets the channel quality to a handover preparation level (hereinafter abbreviated as “HO preparation level”) that is lower than the HO level. It is determined whether or not it has been reached. That is, the channel quality determination unit 107 determines from the channel quality whether or not there is a base station device that is likely to be handed over soon even when there is no base station device that can be handed over.
　速度情報要求部１０８は、回線品質判定部１０７によって回線品質がＨＯ準備レベルに達していると判定された基地局装置がある場合に、端末装置３００の移動速度の情報を要求する速度情報要求を端末装置３００へ送信する。本実施の形態においては、ターゲット基地局２００から端末装置３００への下り回線の回線品質がＨＯ準備レベルに達し、その後ＨＯレベルに達するものとして説明する。 When there is a base station apparatus whose line quality has been determined to have reached the HO preparation level by the line quality determining unit 107, the speed information requesting unit 108 issues a speed information request for requesting information on the moving speed of the terminal apparatus 300. It transmits to the terminal device 300. In the present embodiment, description will be made assuming that the channel quality of the downlink from the target base station 200 to the terminal device 300 reaches the HO preparation level and then reaches the HO level.
　ＨＯ指示部１０９は、回線品質判定部１０７によって回線品質がＨＯレベルに達していると判定された基地局装置がある場合に、この基地局装置へのハンドオーバを指示するＨＯ指示を端末装置３００へ送信する。また、ＨＯ指示部１０９は、ハンドオーバ先の基地局装置に対しても、端末装置３００がハンドオーバする旨を通知する。すなわち、本実施の形態においては、ＨＯ指示部１０９は、ターゲット基地局２００に対して、端末装置３００がハンドオーバする旨を通知する。 When there is a base station apparatus whose line quality has been determined to have reached the HO level by the line quality determination section 107, the HO instruction section 109 sends a HO instruction to instruct the handover to the base station apparatus to the terminal apparatus 300. Send. Also, the HO instruction unit 109 notifies the handover destination base station apparatus that the terminal apparatus 300 is to be handed over. That is, in the present embodiment, the HO instruction unit 109 notifies the target base station 200 that the terminal device 300 is to be handed over.
　速度情報転送部１１０は、受信処理部１０２によって受信処理される受信信号から、端末装置３００の移動速度を含む速度情報を取得し、ターゲット基地局２００へ転送する。上述したように、ターゲット基地局２００の回線品質がＨＯ準備レベルに達すると、速度情報要求部１０８が速度情報要求を送信するため、速度情報転送部１１０は、回線品質がＨＯ準備レベルに達した際に、速度情報を端末装置３００から受信してターゲット基地局２００へ転送する。 The speed information transfer unit 110 acquires speed information including the moving speed of the terminal device 300 from the reception signal received and processed by the reception processing unit 102, and transfers the speed information to the target base station 200. As described above, when the line quality of the target base station 200 reaches the HO preparation level, the speed information request unit 108 transmits the speed information request, so that the speed information transfer unit 110 reaches the HO preparation level. In this case, the speed information is received from the terminal device 300 and transferred to the target base station 200.
　制御情報転送部１１１は、速度情報転送部１１０が速度情報を転送した後、端末装置３００によるパイロット信号の送信間隔を制御する制御情報をターゲット基地局２００から受信し、端末装置３００へ転送する。具体的には、ターゲット基地局２００が固定ビームを形成する基地局装置である場合には、制御情報転送部１１１は、ハンドオーバ後にパイロット信号の送信間隔を比較的長い固定の間隔に設定させる制御情報を端末装置３００へ転送する。一方、ターゲット基地局２００が追従ビームを形成する基地局装置である場合には、ハンドオーバ前から端末装置３００の移動速度に応じた送信間隔でパイロット信号を送信させる制御情報を端末装置３００へ転送する。つまり、ターゲット基地局２００が追従ビームを形成する場合には、制御情報転送部１１１は、移動速度に応じた比較的短い間隔でパイロット信号を送信させる制御情報を端末装置３００へ転送する。 The control information transfer unit 111 receives the control information for controlling the transmission interval of the pilot signal by the terminal device 300 from the target base station 200 and transfers the control information to the terminal device 300 after the speed information transfer unit 110 transfers the speed information. Specifically, when the target base station 200 is a base station apparatus that forms a fixed beam, the control information transfer unit 111 sets control information for setting the transmission interval of pilot signals to a relatively long fixed interval after handover. Is transferred to the terminal device 300. On the other hand, when the target base station 200 is a base station apparatus that forms a tracking beam, control information for transmitting a pilot signal is transmitted to the terminal apparatus 300 at a transmission interval corresponding to the moving speed of the terminal apparatus 300 before the handover. . That is, when the target base station 200 forms a tracking beam, the control information transfer unit 111 transfers control information for transmitting pilot signals to the terminal device 300 at relatively short intervals according to the moving speed.
　図３は、一実施の形態に係るターゲット基地局２００の構成を示すブロック図である。なお、基地局装置１００、２００は、ソース基地局であるかターゲット基地局であるかに関わらず同等の構成を有するが、図３においては、ターゲット基地局としての構成を図示しており、他の構成については図示を省略している。図３に示すターゲット基地局２００は、送信処理部２０１、受信処理部２０２、ビーム制御部２０３、位相制御部２０４、速度情報受信部２０５、送信間隔制御部２０６及び制御情報送信部２０７を有する。 FIG. 3 is a block diagram showing a configuration of the target base station 200 according to the embodiment. The base station apparatuses 100 and 200 have the same configuration regardless of whether they are source base stations or target base stations, but FIG. 3 shows the configuration as a target base station. The illustration of this configuration is omitted. The target base station 200 illustrated in FIG. 3 includes a transmission processing unit 201, a reception processing unit 202, a beam control unit 203, a phase control unit 204, a speed information reception unit 205, a transmission interval control unit 206, and a control information transmission unit 207.
　送信処理部２０１は、端末装置３００に対して送信する送信信号に送信処理を施す。具体的には、送信処理部２０１は、送信信号のＤ／Ａ変換及びアップコンバートなどを実行し、アンテナを介して端末装置３００へ送信する。送信処理部２０１が送信処理を施す送信信号には、端末装置３００がハンドオーバ時にターゲット基地局２００との接続を確立するための信号などが含まれる。 The transmission processing unit 201 performs transmission processing on a transmission signal transmitted to the terminal device 300. Specifically, the transmission processing unit 201 performs D / A conversion, up-conversion, and the like of the transmission signal, and transmits to the terminal device 300 via the antenna. The transmission signal to which the transmission processing unit 201 performs transmission processing includes a signal for the terminal device 300 to establish a connection with the target base station 200 at the time of handover.
　受信処理部２０２は、端末装置３００が送信しアンテナを介して受信された受信信号に受信処理を施す。具体的には、受信処理部２０２は、受信信号のダウンコンバード及びＡ／Ｄ変換などを実行する。受信処理部２０２が受信処理を施す受信信号には、端末装置３００から送信されたパイロット信号などが含まれる。 The reception processing unit 202 performs reception processing on the received signal transmitted from the terminal device 300 and received via the antenna. Specifically, the reception processing unit 202 performs down-conversion and A / D conversion of the received signal. The reception signal to which the reception processing unit 202 performs reception processing includes a pilot signal transmitted from the terminal device 300 and the like.
　ビーム制御部２０３は、固定ビーム又は追従ビームを形成するためのアンテナ素子ごとの位相を算出し、算出した位相を位相制御部２０４に設定する。すなわち、ビーム制御部２０３は、ターゲット基地局２００が固定ビームを形成する基地局装置である場合には、固定ビームを形成する方向に応じたアンテナ素子ごとの位相を算出して位相制御部２０４に設定する。また、ビーム制御部２０３は、ターゲット基地局２００が追従ビームを形成する基地局装置である場合には、受信処理部２０２によって受信処理されたパイロット信号を取得し、パイロット信号の到来方向を推定することにより、端末装置３００の位置を推定する。そして、ビーム制御部２０３は、推定した端末装置３００の位置の方向に応じたアンテナ素子ごとの位相を算出して位相制御部２０４に設定する。なお、ビーム制御部２０３は、送信間隔制御部２０６から、端末装置３００によるパイロット信号の送信間隔の通知を受け、この送信間隔で送信されるパイロット信号を用いて到来方向推定を実行する。 The beam control unit 203 calculates a phase for each antenna element for forming a fixed beam or a tracking beam, and sets the calculated phase in the phase control unit 204. That is, when the target base station 200 is a base station apparatus that forms a fixed beam, the beam control unit 203 calculates the phase for each antenna element according to the direction in which the fixed beam is formed, and sends it to the phase control unit 204. Set. In addition, when the target base station 200 is a base station apparatus that forms a tracking beam, the beam control unit 203 acquires the pilot signal received by the reception processing unit 202 and estimates the arrival direction of the pilot signal. Thus, the position of the terminal device 300 is estimated. Then, the beam control unit 203 calculates a phase for each antenna element according to the estimated position direction of the terminal device 300 and sets the calculated phase in the phase control unit 204. The beam control unit 203 receives a notification of the transmission interval of the pilot signal from the terminal device 300 from the transmission interval control unit 206, and executes the arrival direction estimation using the pilot signal transmitted at this transmission interval.
　位相制御部２０４は、ビーム制御部２０３によって設定された位相回転をアンテナ素子それぞれの信号に付与することにより、固定ビーム又は追従ビームを形成する。 The phase control unit 204 forms a fixed beam or a tracking beam by applying the phase rotation set by the beam control unit 203 to the signal of each antenna element.
　速度情報受信部２０５は、ソース基地局１００の速度情報転送部１１０から転送される速度情報を受信する。この速度情報は、端末装置３００におけるターゲット基地局２００の回線品質がＨＯ準備レベルに達した際の端末装置３００の移動速度を含む。 The speed information receiving unit 205 receives the speed information transferred from the speed information transferring unit 110 of the source base station 100. This speed information includes the moving speed of the terminal device 300 when the channel quality of the target base station 200 in the terminal device 300 reaches the HO preparation level.
　送信間隔制御部２０６は、ターゲット基地局２００が固定ビームを形成する基地局装置であるか追従ビームを形成する基地局装置であるかを判断し、端末装置３００によるパイロット信号の送信間隔を決定する。具体的には、送信間隔制御部２０６は、ターゲット基地局２００が固定ビームを形成する基地局装置である場合には、パイロット信号の送信間隔を例えば１スロットに１回などと比較的長い間隔にすると決定する。 The transmission interval control unit 206 determines whether the target base station 200 is a base station device that forms a fixed beam or a base station device that forms a tracking beam, and determines a transmission interval of pilot signals by the terminal device 300. . Specifically, when the target base station 200 is a base station apparatus that forms a fixed beam, the transmission interval control unit 206 sets the pilot signal transmission interval to a relatively long interval such as once per slot. Then decide.
　また、送信間隔制御部２０６は、ターゲット基地局２００が追従ビームを形成する基地局装置である場合には、速度情報に基づいて、端末装置３００の移動速度に応じた送信間隔を決定する。例えば、送信間隔制御部２０６は、端末装置３００の移動速度が時速ｘｋｍである場合に、パイロット信号の送信間隔を１スロットにｘ回などと決定しても良い。ただし、送信間隔制御部２０６は、ターゲット基地局２００が追従ビームを形成する場合には、固定ビームを形成する場合と比較して短い送信間隔を決定する。すなわち、送信間隔制御部２０６は、ターゲット基地局２００が追従ビームを形成する場合には、固定ビームを形成する場合よりも頻繁に端末装置３００からパイロット信号が送信されるように送信間隔を決定する。 Further, when the target base station 200 is a base station device that forms a tracking beam, the transmission interval control unit 206 determines a transmission interval according to the moving speed of the terminal device 300 based on the speed information. For example, the transmission interval control unit 206 may determine that the transmission interval of the pilot signal is x times per slot when the moving speed of the terminal device 300 is xkm / hour. However, when the target base station 200 forms a tracking beam, the transmission interval control unit 206 determines a shorter transmission interval than when a fixed beam is formed. That is, the transmission interval control unit 206 determines the transmission interval so that the pilot signal is transmitted from the terminal device 300 more frequently when the target base station 200 forms a tracking beam than when a fixed beam is formed. .
　制御情報送信部２０７は、送信間隔制御部２０６によって決定されたパイロット信号の送信間隔を端末装置３００へ通知するための制御情報を、ソース基地局１００を介して端末装置３００へ送信する。具体的には、制御情報送信部２０７は、ターゲット基地局２００が固定ビームを形成する場合には、ハンドオーバしてソース基地局１００との接続が解除された後に、端末装置３００にパイロット信号の送信間隔を変更させる旨の制御情報を送信する。一方、制御情報送信部２０７は、ターゲット基地局２００が追従ビームを形成する場合には、ハンドオーバ前の現時点から、端末装置３００にパイロット信号の送信間隔を変更させる旨の制御情報を送信する。すなわち、制御情報送信部２０７は、ターゲット基地局２００が固定ビームを形成する場合には、ハンドオーバ後にパイロット信号の送信間隔を比較的長くさせる制御情報を送信し、ターゲット基地局２００が追従ビームを形成する場合には、ハンドオーバ前からパイロット信号の送信間隔を比較的短くさせる制御情報を送信する。 The control information transmission unit 207 transmits control information for notifying the terminal device 300 of the transmission interval of the pilot signal determined by the transmission interval control unit 206 to the terminal device 300 via the source base station 100. Specifically, when the target base station 200 forms a fixed beam, the control information transmission unit 207 transmits a pilot signal to the terminal device 300 after performing handover and releasing the connection with the source base station 100. Control information for changing the interval is transmitted. On the other hand, when the target base station 200 forms a follow-up beam, the control information transmission unit 207 transmits control information indicating that the terminal device 300 changes the transmission interval of the pilot signal from the current time before the handover. That is, when the target base station 200 forms a fixed beam, the control information transmission unit 207 transmits control information that makes the pilot signal transmission interval relatively long after handover, and the target base station 200 forms a tracking beam. In this case, control information for relatively shortening the pilot signal transmission interval is transmitted before the handover.
　図４は、一実施の形態に係る端末装置３００の構成を示すブロック図である。図４に示す端末装置３００は、受信処理部３０１、送信処理部３０２、回線品質測定部３０３、速度情報生成部３０４、制御情報取得部３０５、パイロット信号生成部３０６及び送信間隔制御部３０７を有する。 FIG. 4 is a block diagram illustrating a configuration of the terminal device 300 according to an embodiment. 4 includes a reception processing unit 301, a transmission processing unit 302, a line quality measurement unit 303, a speed information generation unit 304, a control information acquisition unit 305, a pilot signal generation unit 306, and a transmission interval control unit 307. .
　受信処理部３０１は、ソース基地局１００が送信しアンテナを介して受信された受信信号に受信処理を施す。具体的には、受信処理部３０１は、受信信号のダウンコンバード及びＡ／Ｄ変換などを実行する。受信処理部３０１が受信処理を施す受信信号には、回線品質測定要求、速度情報要求及び制御情報などが含まれる。 The reception processing unit 301 performs reception processing on the received signal transmitted from the source base station 100 and received via the antenna. Specifically, the reception processing unit 301 performs down-conversion and A / D conversion of the received signal. The reception signal subjected to reception processing by the reception processing unit 301 includes a line quality measurement request, a speed information request, control information, and the like.
　送信処理部３０２は、ソース基地局１００又はターゲット基地局２００に対して送信する送信信号に送信処理を施す。具体的には、送信処理部３０２は、送信信号のＤ／Ａ変換及びアップコンバートなどを実行し、アンテナを介して送信する。送信処理部３０２が送信処理を施す送信信号には、回線品質情報、速度情報及びパイロット信号などが含まれる。 The transmission processing unit 302 performs transmission processing on a transmission signal transmitted to the source base station 100 or the target base station 200. Specifically, the transmission processing unit 302 performs D / A conversion, up-conversion, and the like of the transmission signal and transmits it via the antenna. The transmission signal to which the transmission processing unit 302 performs transmission processing includes line quality information, speed information, a pilot signal, and the like.
　回線品質測定部３０３は、ソース基地局１００から送信された回線品質測定要求が受信されると、ターゲット基地局２００を含む周辺の基地局装置と端末装置３００との間の下り回線の回線品質を測定する。そして、回線品質測定部３０３は、各基地局装置の回線品質を含む回線品質情報を生成し、送信処理部３０２を介してソース基地局１００へ送信する。 When the channel quality measurement unit 303 receives the channel quality measurement request transmitted from the source base station 100, the channel quality measurement unit 303 determines the channel quality of the downlink between the peripheral base station apparatus including the target base station 200 and the terminal apparatus 300. taking measurement. Then, the line quality measuring unit 303 generates line quality information including the line quality of each base station apparatus, and transmits the line quality information to the source base station 100 via the transmission processing unit 302.
　速度情報生成部３０４は、ソース基地局１００から送信された速度情報要求が受信されると、端末装置３００の移動速度を取得し、移動速度の情報を含む速度情報を生成する。速度情報生成部３０４は、例えば端末装置３００が搭載される車両の速度計から移動速度を取得しても良く、ドップラー周波数を測定して移動速度を取得しても良い。また、速度情報生成部３０４は、例えばＧＰＳ（Global　Positioning　System）を用いて車両の位置座標を取得し、単位時間当たりの車両の移動距離を算出することにより移動速度を取得しても良い。そして、速度情報生成部３０４は、端末装置３００の移動速度を含む速度情報を送信処理部３０２を介してソース基地局１００へ送信する。 When the speed information request transmitted from the source base station 100 is received, the speed information generation unit 304 acquires the moving speed of the terminal device 300 and generates speed information including the moving speed information. For example, the speed information generation unit 304 may acquire a moving speed from a speedometer of a vehicle on which the terminal device 300 is mounted, or may measure a Doppler frequency to acquire a moving speed. Further, the speed information generation unit 304 may acquire the moving speed by acquiring the position coordinates of the vehicle using, for example, GPS (Global Positioning System) and calculating the moving distance of the vehicle per unit time. Then, the speed information generation unit 304 transmits speed information including the moving speed of the terminal device 300 to the source base station 100 via the transmission processing unit 302.
　制御情報取得部３０５は、ターゲット基地局２００の制御情報送信部２０７から送信され、ソース基地局１００によって転送された制御情報を取得する。この制御情報は、パイロット信号の送信間隔と、パイロット信号の送信間隔をハンドオーバ前後のどちらに変更すべきかとを指示する情報である。 The control information acquisition unit 305 acquires the control information transmitted from the control information transmission unit 207 of the target base station 200 and transferred by the source base station 100. This control information is information for instructing whether the pilot signal transmission interval and the pilot signal transmission interval should be changed before or after the handover.
　パイロット信号生成部３０６は、既知の信号であり、端末装置３００を識別可能な情報を含むパイロット信号を生成する。パイロット信号は、ソース基地局１００及びターゲット基地局２００が端末装置３００の位置を推定するために用いられるほか、端末装置３００から各基地局装置までの上り回線のチャネル推定などに用いられても良い。 Pilot signal generation section 306 generates a pilot signal that is a known signal and includes information that can identify terminal apparatus 300. The pilot signal is used for the source base station 100 and the target base station 200 to estimate the position of the terminal device 300, and may be used for channel estimation of the uplink from the terminal device 300 to each base station device. .
　送信間隔制御部３０７は、制御情報取得部３０５によって取得された制御情報に従って、パイロット信号の送信間隔を制御する。具体的には、送信間隔制御部３０７は、ハンドオーバ後にパイロット信号の送信間隔を比較的長くすることを指示する制御情報が取得された場合には、ターゲット基地局２００へのハンドオーバが完了後にパイロット信号の送信間隔を調整する。換言すれば、送信間隔制御部３０７は、ソース基地局１００との通信中は現在の送信間隔を維持し、ソース基地局１００との接続が解除された後に、パイロット信号の送信間隔を比較的長くする。これにより、ターゲット基地局２００が固定ビームを形成する場合でも、端末装置３００がハンドオーバするまでは、ソース基地局１００が追従ビームを形成することができる。 The transmission interval control unit 307 controls the transmission interval of the pilot signal according to the control information acquired by the control information acquisition unit 305. Specifically, the transmission interval control unit 307 obtains the pilot signal after the handover to the target base station 200 is completed when control information instructing to make the transmission interval of the pilot signal relatively long after the handover is acquired. Adjust the transmission interval. In other words, the transmission interval control unit 307 maintains the current transmission interval during communication with the source base station 100, and after the connection with the source base station 100 is released, the transmission interval of the pilot signal is relatively long. To do. Thereby, even when the target base station 200 forms a fixed beam, the source base station 100 can form a tracking beam until the terminal device 300 is handed over.
　一方、送信間隔制御部３０７は、ハンドオーバ前にパイロット信号の送信間隔を比較的短くすることを指示する制御情報が取得された場合には、ターゲット基地局２００へのハンドオーバ前にパイロット信号の送信間隔を調整する。換言すれば、送信間隔制御部３０７は、ソース基地局１００と通信中の現時点から即座に、パイロット信号の送信間隔を比較的短くする。これにより、ターゲット基地局２００が追従ビームを形成する場合は、端末装置３００がハンドオーバする前から頻繁にパイロット信号が送信され、ターゲット基地局２００があらかじめ端末装置３００の位置を推定して追従ビームを形成することができる。 On the other hand, the transmission interval control unit 307 acquires the pilot signal transmission interval before the handover to the target base station 200 when the control information instructing to relatively shorten the transmission interval of the pilot signal is acquired before the handover. Adjust. In other words, the transmission interval control unit 307 relatively shortens the transmission interval of the pilot signal immediately from the current point of communication with the source base station 100. As a result, when the target base station 200 forms a tracking beam, pilot signals are frequently transmitted before the terminal device 300 is handed over, and the target base station 200 estimates the position of the terminal device 300 in advance and transmits the tracking beam. Can be formed.
　次に、ソース基地局１００の動作について、図５に示すフロー図を参照しながら説明する。 Next, the operation of the source base station 100 will be described with reference to the flowchart shown in FIG.
　端末装置３００と通信中のソース基地局１００においては、回線品質測定要求部１０５によって、周期的に回線品質測定要求が端末装置３００へ送信される（ステップＳ１０１）。回線品質測定要求が送信されると、端末装置３００は、ターゲット基地局２００を含む周辺の基地局装置の回線品質を測定し、回線品質情報を送信する。 In the source base station 100 in communication with the terminal device 300, the channel quality measurement request unit 105 periodically transmits a channel quality measurement request to the terminal device 300 (step S101). When the channel quality measurement request is transmitted, the terminal device 300 measures the channel quality of the surrounding base station devices including the target base station 200, and transmits the channel quality information.
　回線品質情報は、ソース基地局１００によって受信され（ステップＳ１０２）、回線品質情報取得部１０６によって取得される。そして、回線品質判定部１０７によって、回線品質がＨＯレベルに達する基地局装置があるか否かが判定される（ステップＳ１０３）。この判定の結果、回線品質がＨＯレベルに達する基地局装置がある場合には（ステップＳ１０３Ｙｅｓ）、ＨＯ指示部１０９によって、該当する基地局装置及び端末装置３００に対して端末装置３００のハンドオーバが指示される（ステップＳ１０４）。 The channel quality information is received by the source base station 100 (step S102) and acquired by the channel quality information acquisition unit 106. Then, the channel quality determination unit 107 determines whether there is a base station apparatus whose channel quality reaches the HO level (step S103). As a result of the determination, if there is a base station apparatus whose channel quality reaches the HO level (step S103 Yes), the HO instruction unit 109 instructs the corresponding base station apparatus and the terminal apparatus 300 to hand over the terminal apparatus 300. (Step S104).
　一方、回線品質がＨＯレベルに達する基地局装置がない場合には（ステップＳ１０３Ｎｏ）、引き続き回線品質判定部１０７によって、回線品質がＨＯ準備レベルに達する基地局装置があるか否かが判定される（ステップＳ１０５）。すなわち、各基地局装置の回線品質がＨＯレベルよりも小さいＨＯ準備レベルと比較され、まもなく端末装置３００によるハンドオーバが可能になる基地局装置があるか否かが判定される。この判定の結果、回線品質がＨＯ準備レベルに達する基地局装置がない場合には（ステップＳ１０５Ｎｏ）、端末装置３００がソース基地局１００との通信を継続することから、周期的な回線品質測定要求が繰り返される（ステップＳ１０１）。 On the other hand, when there is no base station apparatus whose line quality reaches the HO level (No in step S103), the line quality determination unit 107 continues to determine whether or not there is a base station apparatus whose line quality reaches the HO preparation level. (Step S105). That is, the channel quality of each base station apparatus is compared with an HO preparation level smaller than the HO level, and it is determined whether there is a base station apparatus that can be handed over by the terminal apparatus 300 soon. As a result of this determination, if there is no base station apparatus whose line quality reaches the HO preparation level (No in step S105), the terminal apparatus 300 continues communication with the source base station 100, so that a periodic line quality measurement request is made. Is repeated (step S101).
　また、回線品質がＨＯ準備レベルに達する基地局装置がある場合には（ステップＳ１０５Ｙｅｓ）、速度情報要求部１０８によって、端末装置３００に対して速度情報を要求する速度情報要求が送信される（ステップＳ１０６）。速度情報要求に対する応答として速度情報が端末装置３００から受信されると、速度情報は、速度情報転送部１１０によって、回線品質がＨＯ準備レベルに達している基地局装置（ターゲット基地局２００）へ転送される（ステップＳ１０７）。 If there is a base station apparatus whose line quality reaches the HO preparation level (Yes at Step S105), the speed information requesting unit 108 transmits a speed information request for requesting speed information to the terminal apparatus 300 (Step S105). S106). When the speed information is received from the terminal device 300 as a response to the speed information request, the speed information is transferred by the speed information transfer unit 110 to the base station apparatus (target base station 200) whose line quality has reached the HO preparation level. (Step S107).
　速度情報がターゲット基地局２００へ転送されると、ターゲット基地局２００においては、速度情報に基づいて端末装置３００によるパイロット信号の送信間隔が決定され、送信間隔を示す制御情報がソース基地局１００へ送信される。この制御情報は、制御情報転送部１１１によって受信され、送信処理部１０１を介して端末装置３００へ転送される（ステップＳ１０８）。これにより、端末装置３００は、ターゲット基地局２００へのハンドオーバ前に、あらかじめパイロット信号の送信間隔を変更することができる。 When the speed information is transferred to the target base station 200, the target base station 200 determines the transmission interval of the pilot signal by the terminal device 300 based on the speed information, and the control information indicating the transmission interval is sent to the source base station 100. Sent. This control information is received by the control information transfer unit 111 and transferred to the terminal device 300 via the transmission processing unit 101 (step S108). Thereby, the terminal device 300 can change the transmission interval of the pilot signal in advance before the handover to the target base station 200.
　その後、周期的な回線品質測定要求が繰り返され（ステップＳ１０１）、ターゲット基地局２００の回線品質がＨＯレベルに達すると（ステップＳ１０３Ｙｅｓ）、ＨＯ指示部１０９によって、ターゲット基地局２００及び端末装置３００に対して端末装置３００のハンドオーバが指示される（ステップＳ１０４）。本実施の形態においては、端末装置３００がターゲット基地局２００へハンドオーバする場合、ターゲット基地局２００の回線品質がＨＯ準備レベルに達した時点であらかじめ端末装置３００によるパイロット信号の送信間隔が変更されている。このため、ターゲット基地局２００は、端末装置３００の位置を推定するのに十分な送信間隔でパイロット信号を受信することができ、追従ビームを形成することができる。 Thereafter, the periodic channel quality measurement request is repeated (step S101). When the channel quality of the target base station 200 reaches the HO level (step S103 Yes), the HO instruction unit 109 causes the target base station 200 and the terminal device 300 to On the other hand, the handover of the terminal device 300 is instructed (step S104). In the present embodiment, when the terminal apparatus 300 is handed over to the target base station 200, the transmission interval of the pilot signal by the terminal apparatus 300 is changed in advance when the channel quality of the target base station 200 reaches the HO preparation level. Yes. For this reason, the target base station 200 can receive a pilot signal at a transmission interval sufficient to estimate the position of the terminal device 300, and can form a tracking beam.
　次に、ターゲット基地局２００の動作について、図６に示すフロー図を参照しながら説明する。 Next, the operation of the target base station 200 will be described with reference to the flowchart shown in FIG.
　端末装置３００におけるターゲット基地局２００の回線品質がＨＯ準備レベルに達すると、端末装置３００の移動速度を示す速度情報がソース基地局１００からターゲット基地局２００へ送信される。速度情報は、ターゲット基地局２００の速度情報受信部２０５によって受信され（ステップＳ２０１）、送信間隔制御部２０６へ出力される。そして、送信間隔制御部２０６によって、ターゲット基地局２００が固定ビームを形成する基地局装置であるか、追従ビームを形成する基地局装置であるかが判定される（ステップＳ２０２）。 When the channel quality of the target base station 200 in the terminal device 300 reaches the HO preparation level, speed information indicating the moving speed of the terminal device 300 is transmitted from the source base station 100 to the target base station 200. The speed information is received by the speed information receiving unit 205 of the target base station 200 (step S201) and output to the transmission interval control unit 206. Then, the transmission interval control unit 206 determines whether the target base station 200 is a base station apparatus that forms a fixed beam or a base station apparatus that forms a tracking beam (step S202).
　ターゲット基地局２００が固定ビームを形成するか追従ビームを形成するかは、あらかじめ設定されていても良く、例えばターゲット基地局２００のセル内の交通状況などに応じて適応的に設定されても良い。交通状況に応じて適応的に設定される場合には、例えばセル内の道路に存在する車の数が所定数以上の場合には固定ビームを形成し、自装置のセル内の道路に存在する車の数が所定数未満の場合には追従ビームを形成する。 Whether the target base station 200 forms a fixed beam or a tracking beam may be set in advance, for example, may be adaptively set according to traffic conditions in the cell of the target base station 200, for example. . When adaptively set according to the traffic situation, for example, when the number of vehicles existing on the road in the cell is a predetermined number or more, a fixed beam is formed and exists on the road in the cell of the own device. When the number of cars is less than a predetermined number, a tracking beam is formed.
　ターゲット基地局２００が固定ビームを形成する場合には（ステップＳ２０２Ｎｏ）、送信間隔制御部２０６によって、指向性ビームを端末装置３００の移動に追従させることが不要であると判断され、端末装置３００の位置の推定が不要であると判断される。そこで、送信間隔制御部２０６によって、端末装置３００によるパイロット信号の送信間隔を例えば１スロットに１回などと比較的長い間隔にすることが決定される。 When the target base station 200 forms a fixed beam (No in step S202), the transmission interval control unit 206 determines that it is not necessary to follow the movement of the terminal device 300 by the transmission interval control unit 206. It is determined that position estimation is unnecessary. Therefore, the transmission interval control unit 206 determines that the transmission interval of the pilot signal by the terminal device 300 is a relatively long interval such as once per slot.
　そして、ターゲット基地局２００へハンドオーバした後にパイロット信号の送信間隔を長い間隔にする旨の制御情報が生成され、制御情報送信部２０７からソース基地局１００へ送信される（ステップＳ２０５）。この制御情報は、ソース基地局１００から端末装置３００へ転送され、端末装置３００は、制御情報に従って、ターゲット基地局２００へハンドオーバした後にパイロット信号の送信間隔を長い間隔に設定する。ハンドオーバ先のターゲット基地局２００では、ビーム制御部２０３及び位相制御部２０４によって固定ビームが形成されるため（ステップＳ２０６）、端末装置３００によるパイロット信号の送信間隔が長くても、ハンドオーバ時に通信品質が低下することはない。 Then, after handover to the target base station 200, control information indicating that the transmission interval of the pilot signal is long is generated and transmitted from the control information transmitting unit 207 to the source base station 100 (step S205). This control information is transferred from the source base station 100 to the terminal device 300, and the terminal device 300 sets the transmission interval of the pilot signal to a long interval after handover to the target base station 200 according to the control information. In the target base station 200 that is the handover destination, a fixed beam is formed by the beam control unit 203 and the phase control unit 204 (step S206). Therefore, even if the transmission interval of the pilot signal by the terminal apparatus 300 is long, the communication quality at the time of handover There is no decline.
　また、端末装置３００は、ハンドオーバするまではパイロット信号の送信間隔を変更しないため、ソース基地局１００が追従ビームを形成する場合には、端末装置３００は、ハンドオーバ前は短い間隔でパイロット信号を送信する。結果として、ソース基地局１００は、端末装置３００がハンドオーバするまで、端末装置３００の位置を推定して追従ビームを形成することができる。 In addition, since the terminal apparatus 300 does not change the transmission interval of the pilot signal until the handover is performed, when the source base station 100 forms a tracking beam, the terminal apparatus 300 transmits the pilot signal at a short interval before the handover. To do. As a result, the source base station 100 can estimate the position of the terminal device 300 and form a tracking beam until the terminal device 300 is handed over.
　一方、ターゲット基地局２００が追従ビームを形成する場合には（ステップＳ２０２Ｙｅｓ）、送信間隔制御部２０６によって、速度情報に基づいてパイロット信号の送信間隔が決定される（ステップＳ２０３）。具体的には、例えば端末装置３００の移動速度が時速ｘｋｍである場合に、パイロット信号の送信間隔を１スロットにｘ回などとすることが決定される。ただし、ターゲット基地局２００が追従ビームを形成する場合には、固定ビームを形成する場合と比較して短い送信間隔にすることが決定される。 On the other hand, when the target base station 200 forms a tracking beam (step S202 Yes), the transmission interval control unit 206 determines the transmission interval of the pilot signal based on the speed information (step S203). Specifically, for example, when the moving speed of the terminal device 300 is x km / h, it is determined that the transmission interval of the pilot signal is x times per slot. However, when the target base station 200 forms a tracking beam, it is determined that the transmission interval is shorter than when a fixed beam is formed.
　そして、ターゲット基地局２００へハンドオーバする前からパイロット信号の送信間隔を短い間隔にする旨の制御情報が生成され、制御情報送信部２０７からソース基地局１００へ送信される（ステップＳ２０４）。この制御情報は、ソース基地局１００から端末装置３００へ転送され、端末装置３００は、制御情報に従って、ターゲット基地局２００へハンドオーバする前の現時点からパイロット信号の送信間隔を短い間隔に設定する。ハンドオーバ先のターゲット基地局２００では、短い送信間隔で送信されるパイロット信号を用いて、ビーム制御部２０３及び位相制御部２０４によって追従ビームが形成される（ステップＳ２０６）。このように、ターゲット基地局２００が追従ビームを形成する場合には、ターゲット基地局２００は、端末装置３００がハンドオーバする前から端末装置３００の位置を推定して追従ビームを形成することができ、ハンドオーバ時の通信品質の低下を抑制することができる。 Then, control information indicating that the pilot signal transmission interval is set to a short interval before handover to the target base station 200 is generated and transmitted from the control information transmitting unit 207 to the source base station 100 (step S204). This control information is transferred from the source base station 100 to the terminal device 300, and the terminal device 300 sets the transmission interval of the pilot signal to a short interval from the current point before the handover to the target base station 200 according to the control information. In the target base station 200 to be handed over, a tracking beam is formed by the beam control unit 203 and the phase control unit 204 using a pilot signal transmitted at a short transmission interval (step S206). Thus, when the target base station 200 forms a tracking beam, the target base station 200 can estimate the position of the terminal device 300 before the terminal device 300 is handed over to form the tracking beam, It is possible to suppress a decrease in communication quality at the time of handover.
　次いで、上記の無線通信システムにおいて、ソース基地局１００が固定ビームを形成し、ターゲット基地局２００が追従ビームを形成する場合の動作について、図７に示すシーケンス図を参照しながら具体的に説明する。 Next, in the wireless communication system described above, the operation when the source base station 100 forms a fixed beam and the target base station 200 forms a tracking beam will be specifically described with reference to the sequence diagram shown in FIG. .
　端末装置３００がソース基地局１００のセルに位置する間は、周期的に回線品質測定要求がソース基地局１００から端末装置３００へ送信される（ステップＳ３０１）。回線品質測定要求が端末装置３００によって受信されると、端末装置３００は、ターゲット基地局２００を含む周辺の基地局装置からの下り回線の回線品質を測定する（ステップＳ３０２）。そして、端末装置３００は、回線品質情報をソース基地局１００へ送信する（ステップＳ３０３）。 While the terminal device 300 is located in the cell of the source base station 100, a channel quality measurement request is periodically transmitted from the source base station 100 to the terminal device 300 (step S301). When the channel quality measurement request is received by the terminal device 300, the terminal device 300 measures the channel quality of the downlink from the surrounding base station devices including the target base station 200 (step S302). And the terminal device 300 transmits line quality information to the source base station 100 (step S303).
　回線品質情報がソース基地局１００によって受信されると、回線品質がＨＯレベル又はＨＯ準備レベルに達する基地局装置があるか否かが判定される。ここでは、ターゲット基地局２００の回線品質がＨＯ準備レベルに達しているものとして説明を進める。ターゲット基地局２００の回線品質がＨＯ準備レベルに達している場合、速度情報要求がソース基地局１００から端末装置３００へ送信され（ステップＳ３０４）、応答として端末装置３００の移動速度を示す速度情報がソース基地局１００へ送信される（ステップＳ３０５）。 When the channel quality information is received by the source base station 100, it is determined whether or not there is a base station apparatus whose channel quality reaches the HO level or the HO preparation level. Here, description will be made assuming that the channel quality of the target base station 200 has reached the HO preparation level. When the channel quality of the target base station 200 has reached the HO preparation level, a speed information request is transmitted from the source base station 100 to the terminal device 300 (step S304), and speed information indicating the moving speed of the terminal device 300 is returned as a response. It is transmitted to the source base station 100 (step S305).
　速度情報は、ソース基地局１００からターゲット基地局２００へ転送され（ステップＳ３０６）、ターゲット基地局２００は、速度情報に基づいて端末装置３００によるパイロット信号の送信間隔を決定する（ステップＳ３０７）。すなわち、ターゲット基地局２００は、自局が追従ビームを形成する基地局装置であるため、端末装置３００の移動速度に応じてパイロット信号の送信間隔を比較的短い間隔に決定する。そして、ハンドオーバ前からパイロット信号の送信間隔を短い間隔にする旨の制御情報が、ターゲット基地局２００からソース基地局１００へ送信される（ステップＳ３０８）。 The speed information is transferred from the source base station 100 to the target base station 200 (step S306), and the target base station 200 determines the transmission interval of the pilot signal by the terminal device 300 based on the speed information (step S307). That is, since the target base station 200 is a base station apparatus that forms a follow-up beam, the target base station 200 determines the pilot signal transmission interval as a relatively short interval according to the moving speed of the terminal device 300. Then, control information indicating that the pilot signal transmission interval is short before handover is transmitted from the target base station 200 to the source base station 100 (step S308).
　制御情報は、ソース基地局１００から端末装置３００へ転送され（ステップＳ３０９）、端末装置３００は、ハンドオーバ前の現時点からパイロット信号の送信間隔を短い間隔に変更する。これにより、ターゲット基地局２００は、パイロット信号を用いて端末装置３００の位置を推定し、端末装置３００の移動に追従する追従ビームの形成を開始する（ステップＳ３１０）。 The control information is transferred from the source base station 100 to the terminal device 300 (step S309), and the terminal device 300 changes the transmission interval of the pilot signal to a short interval from the current time before the handover. Thereby, the target base station 200 estimates the position of the terminal device 300 using the pilot signal, and starts forming a follow-up beam that follows the movement of the terminal device 300 (step S310).
　この時点では、端末装置３００はソース基地局１００と通信中であるため、周期的に回線品質測定要求がソース基地局１００から端末装置３００へ送信される（ステップＳ３１１）。回線品質測定要求が端末装置３００によって受信されると、端末装置３００は、ターゲット基地局２００を含む周辺の基地局装置からの下り回線の回線品質を測定する（ステップＳ３１２）。そして、端末装置３００は、回線品質情報をソース基地局１００へ送信する（ステップＳ３１３）。 At this time, since the terminal apparatus 300 is communicating with the source base station 100, a channel quality measurement request is periodically transmitted from the source base station 100 to the terminal apparatus 300 (step S311). When the terminal device 300 receives the channel quality measurement request, the terminal device 300 measures the downlink channel quality from the surrounding base station devices including the target base station 200 (step S312). Then, the terminal device 300 transmits the line quality information to the source base station 100 (step S313).
　回線品質情報がソース基地局１００によって受信されると、回線品質がＨＯレベル又はＨＯ準備レベルに達する基地局装置があるか否かが判定される。ここでは、ターゲット基地局２００の回線品質がＨＯレベルに達しているものとして説明を進める。ターゲット基地局２００の回線品質がＨＯレベルに達している場合、ハンドオーバ指示がソース基地局１００から端末装置３００及びターゲット基地局２００へ送信され（ステップＳ３１４、Ｓ３１５）、端末装置３００がターゲット基地局２００へのハンドオーバを実行する。このとき、ターゲット基地局２００は、ハンドオーバ前から端末装置３００に対する追従ビームを形成しているため、ハンドオーバ時に伝送速度の低下や通信断が発生することがない。換言すれば、端末装置３００が固定ビームを形成するソース基地局１００から追従ビームを形成するターゲット基地局２００へハンドオーバする場合でも、通信品質の低下を抑制することができる。 When the channel quality information is received by the source base station 100, it is determined whether or not there is a base station apparatus whose channel quality reaches the HO level or the HO preparation level. Here, the description will proceed assuming that the channel quality of the target base station 200 has reached the HO level. When the channel quality of the target base station 200 has reached the HO level, a handover instruction is transmitted from the source base station 100 to the terminal device 300 and the target base station 200 (steps S314 and S315), and the terminal device 300 is transmitted to the target base station 200. Perform a handover to At this time, since the target base station 200 forms a tracking beam for the terminal device 300 before the handover, the transmission rate does not decrease or the communication is not interrupted during the handover. In other words, even when the terminal device 300 is handed over from the source base station 100 that forms a fixed beam to the target base station 200 that forms a tracking beam, it is possible to suppress a decrease in communication quality.
　次いで、上記の無線通信システムにおいて、ソース基地局１００が追従ビームを形成し、ターゲット基地局２００が固定ビームを形成する場合の動作について、図８に示すシーケンス図を参照しながら具体的に説明する。なお、図８において、図７と同じ部分には同じ符号を付し、その詳しい説明を省略する。 Next, in the above wireless communication system, the operation when the source base station 100 forms a tracking beam and the target base station 200 forms a fixed beam will be specifically described with reference to the sequence diagram shown in FIG. . In FIG. 8, the same parts as those in FIG.
　端末装置３００がソース基地局１００のセルに位置する間は、周期的に回線品質測定要求がソース基地局１００から端末装置３００へ送信され、回線品質情報が端末装置３００からソース基地局１００へ返送される（ステップＳ３０１～Ｓ３０３）。そして、ターゲット基地局２００の回線品質がＨＯ準備レベルに達していると、端末装置３００の移動速度を示す速度情報がターゲット基地局２００へ転送される（ステップＳ３０４～Ｓ３０６）。 While the terminal device 300 is located in the cell of the source base station 100, a channel quality measurement request is periodically transmitted from the source base station 100 to the terminal device 300, and the channel quality information is returned from the terminal device 300 to the source base station 100. (Steps S301 to S303). When the channel quality of the target base station 200 reaches the HO preparation level, speed information indicating the moving speed of the terminal device 300 is transferred to the target base station 200 (steps S304 to S306).
　速度情報が転送されると、ターゲット基地局２００においては、自局が追従ビームを形成する基地局装置であるか否かが判定され、ここでは、ターゲット基地局２００が固定ビームを形成する基地局装置であると判定される。このため、追従ビームを形成することが不要であると判定され（ステップＳ４０１）、ターゲット基地局２００へのハンドオーバ後にパイロット信号の送信間隔を長い間隔にする旨の制御情報が、ターゲット基地局２００からソース基地局１００へ送信される（ステップＳ４０２）。すなわち、ターゲット基地局２００は固定ビームを形成するため、端末装置３００の位置を推定する必要がなく、端末装置３００によるパイロット信号の送信間隔は比較的長い間隔でも良い。しかしながら、ソース基地局１００は追従ビームを形成するため、端末装置３００がハンドオーバする前にパイロット信号の送信間隔を長い間隔に変更してしまうと、ソース基地局１００による追従ビームの形成が困難となる。そこで、ハンドオーバ後にパイロット信号の送信間隔を変更させるための制御情報がソース基地局１００へ送信され、端末装置３００へ転送される（ステップＳ４０３）。 When the speed information is transferred, the target base station 200 determines whether or not the own station is a base station apparatus that forms a tracking beam. Here, the target base station 200 forms a fixed beam. It is determined that it is a device. For this reason, it is determined that it is not necessary to form a tracking beam (step S401), and control information indicating that the transmission interval of the pilot signal is long after the handover to the target base station 200 is received from the target base station 200. It is transmitted to the source base station 100 (step S402). That is, since the target base station 200 forms a fixed beam, there is no need to estimate the position of the terminal device 300, and the transmission interval of pilot signals by the terminal device 300 may be a relatively long interval. However, since the source base station 100 forms a tracking beam, if the transmission interval of the pilot signal is changed to a long interval before the terminal device 300 is handed over, it becomes difficult for the source base station 100 to form the tracking beam. . Therefore, control information for changing the transmission interval of the pilot signal after the handover is transmitted to the source base station 100 and transferred to the terminal device 300 (step S403).
　この時点では、端末装置３００はソース基地局１００と通信中であるため、周期的に回線品質測定要求がソース基地局１００から端末装置３００へ送信され、回線品質情報が端末装置３００からソース基地局１００へ返送される（ステップＳ３１１～Ｓ３１３）。そして、ターゲット基地局２００の回線品質がＨＯレベルに達していると、ハンドオーバ指示がソース基地局１００から端末装置３００及びターゲット基地局２００へ送信され（ステップＳ３１４、Ｓ３１５）、端末装置３００がターゲット基地局２００へのハンドオーバを実行する。そして、端末装置３００は、ソース基地局１００によって転送された制御情報に従って、ターゲット基地局２００へハンドオーバしてソース基地局１００との接続を解除した後に、パイロット信号の送信間隔を長い間隔に調整する（ステップＳ４０４）。このため、端末装置３００がハンドオーバするまでは、ソース基地局１００は追従ビームを形成することができ、通信品質が低下することがない。 At this time, since the terminal device 300 is communicating with the source base station 100, a channel quality measurement request is periodically transmitted from the source base station 100 to the terminal device 300, and the channel quality information is transmitted from the terminal device 300 to the source base station. 100 is returned (steps S311 to S313). When the channel quality of the target base station 200 reaches the HO level, a handover instruction is transmitted from the source base station 100 to the terminal device 300 and the target base station 200 (steps S314 and S315), and the terminal device 300 A handover to the station 200 is executed. Then, according to the control information transferred by the source base station 100, the terminal device 300 performs handover to the target base station 200 and releases the connection with the source base station 100, and then adjusts the transmission interval of the pilot signal to a longer interval. (Step S404). For this reason, until the terminal device 300 is handed over, the source base station 100 can form a tracking beam, and communication quality does not deteriorate.
　以上のように、本実施の形態によれば、端末装置の移動速度を示す速度情報をハンドオーバ前にハンドオーバ先のターゲット基地局へ転送し、移動速度に応じて端末装置によるパイロット信号の送信間隔が決定される。そして、ターゲット基地局が追従ビームを形成する場合には、端末装置は、移動速度に応じた送信間隔でパイロット信号を送信し、ターゲット基地局は、ハンドオーバ前からパイロット信号を用いて追従ビームを形成する。このため、端末装置がターゲット基地局へのハンドオーバを実行する際、通信速度の低下や通信断などが発生せず、通信品質の低下を抑制することができる。 As described above, according to the present embodiment, the speed information indicating the moving speed of the terminal device is transferred to the target base station that is the handover destination before the handover, and the transmission interval of the pilot signal by the terminal device is set according to the moving speed. It is determined. When the target base station forms a tracking beam, the terminal device transmits a pilot signal at a transmission interval corresponding to the moving speed, and the target base station forms the tracking beam using the pilot signal before the handover. To do. For this reason, when the terminal device performs a handover to the target base station, the communication speed does not decrease, the communication is not interrupted, and the deterioration of the communication quality can be suppressed.
　なお、上記一実施の形態においては、ターゲット基地局２００が速度情報に基づいて端末装置３００によるパイロット信号の送信間隔を決定するものとしたが、送信間隔の決定は、ソース基地局１００又は端末装置３００が実行しても良い。すなわち、端末装置３００の移動速度とターゲット基地局２００が追従ビームを形成するか否かとを把握している装置であれば、ターゲット基地局２００以外の装置がパイロット信号の送信間隔を決定しても良い。 In the above embodiment, the target base station 200 determines the transmission interval of the pilot signal by the terminal device 300 based on the speed information. However, the transmission interval is determined by the source base station 100 or the terminal device. 300 may execute. In other words, as long as the device knows the moving speed of the terminal device 300 and whether or not the target base station 200 forms a tracking beam, even if a device other than the target base station 200 determines the transmission interval of the pilot signal. good.
　また、上記一実施の形態において、ソース基地局１００及びターゲット基地局２００が通信に使用する周波数は、同一でも異なっていても良い。ソース基地局１００及びターゲット基地局２００の使用周波数が異なる場合には、端末装置３００は、ソース基地局１００との通信中にターゲット基地局２００に対するランダムアクセスを実行し、一時的に２つの基地局装置と同時に通信をしても良い。 In the above-described embodiment, the frequencies used by the source base station 100 and the target base station 200 for communication may be the same or different. When the used frequencies of the source base station 100 and the target base station 200 are different, the terminal device 300 performs random access to the target base station 200 during communication with the source base station 100, and temporarily receives the two base stations. Communication may be performed simultaneously with the device.
　また、ソース基地局１００及びターゲット基地局２００の使用周波数が異なる場合には、端末装置３００は、キャリアアグリゲーションによるソース基地局１００及びターゲット基地局２００との同時通信と、いずれか一方の基地局との通信とを切り替えても良い。このような切り替えは、端末装置３００が通信に用いるセルの変更に相当し、上記一実施の形態におけるハンドオーバ時と同様の動作が可能である。この場合、例えば回線品質が所定のセル変更レベルになると、端末装置３００は、ソース基地局１００との通信に加えてターゲット基地局２００との通信を開始する。また、例えば回線品質がセル変更レベルよりも小さいセル変更準備レベルに達すると、端末装置３００は、必要に応じてパイロット信号の送信間隔を制御する。 Further, when the use frequencies of the source base station 100 and the target base station 200 are different, the terminal device 300 performs simultaneous communication with the source base station 100 and the target base station 200 by carrier aggregation, and either one of the base stations. The communication may be switched. Such switching corresponds to a change of the cell used by the terminal device 300 for communication, and the same operation as that at the time of handover in the above embodiment is possible. In this case, for example, when the channel quality reaches a predetermined cell change level, the terminal device 300 starts communication with the target base station 200 in addition to communication with the source base station 100. For example, when the channel quality reaches a cell change preparation level smaller than the cell change level, the terminal device 300 controls the transmission interval of pilot signals as necessary.
　このように、ハンドオーバであるかセルの変更であるかに関わらず、端末装置３００が接続先を変更又は追加する際には、端末装置３００の移動速度に応じてパイロット信号の送信間隔が制御される。 In this way, regardless of whether it is a handover or a cell change, when the terminal device 300 changes or adds a connection destination, the transmission interval of the pilot signal is controlled according to the moving speed of the terminal device 300. The
　上記一実施の形態に係るソース基地局１００及びターゲット基地局２００は、例えば図９に示すようなハードウェア構成を有する。すなわち、ソース基地局１００及びターゲット基地局２００を含む基地局装置１０は、通信インタフェース（以下「通信Ｉ／Ｆ」と略記する）１１、プロセッサ１２、メモリ１３及び無線処理部１４を有する。 The source base station 100 and the target base station 200 according to the above embodiment have a hardware configuration as shown in FIG. That is, the base station apparatus 10 including the source base station 100 and the target base station 200 includes a communication interface (hereinafter abbreviated as “communication I / F”) 11, a processor 12, a memory 13, and a wireless processing unit 14.
　通信Ｉ／Ｆ１１は、他の基地局装置と通信する例えばＸ２インタフェースなどのインタフェースであり、速度情報及び制御情報を送受信する。したがって、通信Ｉ／Ｆ１１は、ソース基地局１００の速度情報転送部１１０及び制御情報転送部１１１と、ターゲット基地局２００の速度情報受信部２０５及び制御情報送信部２０７とに対応する。 The communication I / F 11 is an interface such as an X2 interface that communicates with other base station apparatuses, and transmits and receives speed information and control information. Therefore, the communication I / F 11 corresponds to the speed information transfer unit 110 and the control information transfer unit 111 of the source base station 100, and the speed information reception unit 205 and the control information transmission unit 207 of the target base station 200.
　プロセッサ１２は、例えばＣＰＵ（Central　Processing　Unit）、ＦＰＧＡ（Field　Programmable　Gate　Array）又はＤＳＰ（Digital　Signal　Processor）などを備え、基地局装置１０全体を制御する。プロセッサ１２は、ソース基地局１００のビーム制御部１０３、回線品質測定要求部１０５、回線品質情報取得部１０６、回線品質判定部１０７、速度情報要求部１０８及びＨＯ指示部１０９に対応する。また、プロセッサ１２は、ターゲット基地局２００のビーム制御部２０３、送信間隔制御部２０６及びＨＯ制御部２０８に対応する。 The processor 12 includes, for example, a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), and the like, and controls the entire base station apparatus 10. The processor 12 corresponds to the beam control unit 103, the channel quality measurement request unit 105, the channel quality information acquisition unit 106, the channel quality determination unit 107, the speed information request unit 108, and the HO instruction unit 109 of the source base station 100. The processor 12 corresponds to the beam control unit 203, the transmission interval control unit 206, and the HO control unit 208 of the target base station 200.
　メモリ１３は、例えばＲＡＭ（Random　Access　Memory）又はＲＯＭ（Read　Only　Memory）などを備え、プロセッサ１２によって処理が実行される際に、種々の情報を記憶する。 The memory 13 includes, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores various types of information when processing is executed by the processor 12.
　無線処理部１４は、端末装置３００との間で送受信される信号に対して無線処理を実行する。すなわち、無線処理部１４は、回線品質測定要求及び速度情報要求などを送信したり、回線品質情報、速度情報及びパイロット信号を受信したりする。したがって、無線処理部１４は、ソース基地局１００の送信処理部１０１、受信処理部１０２及び位相制御部１０４と、ターゲット基地局２００の送信処理部２０１、受信処理部２０２及び位相制御部２０４とに対応する。 The wireless processing unit 14 performs wireless processing on a signal transmitted / received to / from the terminal device 300. That is, the wireless processing unit 14 transmits a line quality measurement request and a speed information request, and receives line quality information, speed information, and a pilot signal. Therefore, the radio processing unit 14 includes the transmission processing unit 101, the reception processing unit 102, and the phase control unit 104 of the source base station 100, and the transmission processing unit 201, the reception processing unit 202, and the phase control unit 204 of the target base station 200. Correspond.
　また、上記一実施の形態に係る端末装置３００は、例えば図１０に示すようなハードウェア構成を有する。すなわち、端末装置３００を含む端末装置２０は、無線処理部２１、プロセッサ２２及びメモリ２３を有する。 Further, the terminal device 300 according to the embodiment has a hardware configuration as shown in FIG. 10, for example. That is, the terminal device 20 including the terminal device 300 includes the wireless processing unit 21, the processor 22, and the memory 23.
　無線処理部２１は、ソース基地局１００及びターゲット基地局２００との間で送受信される信号に対して無線処理を実行する。すなわち、無線処理部２１は、回線品質情報、速度情報及びパイロット信号などを送信したり、回線品質測定要求及び速度情報要求を受信したりする。したがって、無線処理部２１は、端末装置３００の受信処理部３０１及び送信処理部３０２に対応する。 The radio processing unit 21 performs radio processing on a signal transmitted / received between the source base station 100 and the target base station 200. That is, the wireless processing unit 21 transmits line quality information, speed information, pilot signals, and the like, and receives a line quality measurement request and a speed information request. Therefore, the wireless processing unit 21 corresponds to the reception processing unit 301 and the transmission processing unit 302 of the terminal device 300.
　プロセッサ２２は、例えばＣＰＵ、ＦＰＧＡ又はＤＳＰなどを備え、端末装置２０全体を制御する。プロセッサ２２は、端末装置３００の回線品質測定部３０３、速度情報生成部３０４、制御情報取得部３０５、パイロット信号生成部３０６及び送信間隔制御部３０７に対応する。 The processor 22 includes, for example, a CPU, FPGA, or DSP, and controls the terminal device 20 as a whole. The processor 22 corresponds to the line quality measurement unit 303, the speed information generation unit 304, the control information acquisition unit 305, the pilot signal generation unit 306, and the transmission interval control unit 307 of the terminal device 300.
　メモリ２３は、例えばＲＡＭ又はＲＯＭなどを備え、プロセッサ２２によって処理が実行される際に、種々の情報を記憶する。 The memory 23 includes, for example, a RAM or a ROM, and stores various information when processing is executed by the processor 22.
　１１　通信Ｉ／Ｆ
　１２、２２　プロセッサ
　１３、２３　メモリ
　１４、２１　無線処理部
　１０１、２０１、３０２　送信処理部
　１０２、２０２、３０１　受信処理部
　１０３、２０３　ビーム制御部
　１０４、２０４　位相制御部
　１０５　回線品質測定要求部
　１０６　回線品質情報取得部
　１０７　回線品質判定部
　１０８　速度情報要求部
　１０９　ＨＯ指示部
　１１０　速度情報転送部
　１１１　制御情報転送部
　２０５　速度情報受信部
　２０６　送信間隔制御部
　２０７　制御情報送信部
　２０８　ＨＯ制御部
　３０３　回線品質測定部
　３０４　速度情報生成部
　３０５　制御情報取得部
　３０６　パイロット信号生成部
　３０７　送信間隔制御部 11 Communication I / F
12, 22 Processor 13, 23 Memory 14, 21 Radio processing unit 101, 201, 302 Transmission processing unit 102, 202, 301 Reception processing unit 103, 203 Beam control unit 104, 204 Phase control unit 105 Channel quality measurement request unit 106 Channel Quality information acquisition unit 107 Line quality determination unit 108 Speed information request unit 109 HO instruction unit 110 Speed information transfer unit 111 Control information transfer unit 205 Speed information reception unit 206 Transmission interval control unit 207 Control information transmission unit 208 HO control unit 303 Line quality Measurement unit 304 Speed information generation unit 305 Control information acquisition unit 306 Pilot signal generation unit 307 Transmission interval control unit

Claims (8)

  1. 　端末装置の移動速度に関する制御情報を取得する取得部と、
    　前記端末装置が第１の基地局装置から第２の基地局装置へ接続先を変更する際に、前記取得部によって取得された制御情報に基づいて、前記端末装置による既知信号の送信間隔を制御する制御部と、
    　前記制御部によって制御された送信間隔に関する制御情報を送信する送信部と
    　を有することを特徴とする基地局装置。     An acquisition unit for acquiring control information regarding the moving speed of the terminal device;
    When the terminal apparatus changes the connection destination from the first base station apparatus to the second base station apparatus, the transmission interval of known signals by the terminal apparatus is controlled based on the control information acquired by the acquisition unit A control unit,
    A base station apparatus comprising: a transmission unit that transmits control information related to a transmission interval controlled by the control unit.
  2. 　前記制御部は、
    　前記端末装置に対する送信ビームを制御する前記第２の基地局装置が前記端末装置に対する追従ビームを用いる場合に、既知信号の送信間隔を制御する
    　ことを特徴とする請求項１記載の基地局装置。     The controller is
    The base station apparatus according to claim 1, wherein when the second base station apparatus that controls a transmission beam for the terminal apparatus uses a tracking beam for the terminal apparatus, a transmission interval of known signals is controlled.
  3. 　前記制御部は、
    　前記第２の基地局装置が前記端末装置に対する固定ビームを用いる場合に、既知信号の送信間隔を制御することを特徴とする請求項２記載の基地局装置。     The controller is
    The base station apparatus according to claim 2, wherein when the second base station apparatus uses a fixed beam for the terminal apparatus, the transmission interval of the known signal is controlled.
  4. 　前記制御部は、
    　前記端末装置の移動速度に対応して既知信号の送信間隔を制御することを特徴とする請求項１記載の基地局装置。     The controller is
    The base station apparatus according to claim 1, wherein a transmission interval of known signals is controlled in accordance with a moving speed of the terminal apparatus.
  5. 　端末装置の移動速度に関する制御情報を取得し、
    　前記端末装置が第１の基地局装置から第２の基地局装置へ接続先を変更する際に、前記端末装置による既知信号の送信間隔を制御し、
    　制御された送信間隔を示す制御情報を送信する
    　ことを特徴とする送信間隔制御方法。     Get control information about the moving speed of the terminal device,
    When the terminal device changes the connection destination from the first base station device to the second base station device, the transmission interval of known signals by the terminal device is controlled,
    A transmission interval control method, characterized by transmitting control information indicating a controlled transmission interval.
  6. 　端末装置と、第１の基地局装置と、第２の基地局装置とを有する無線通信システムであって、
    　前記第２の基地局装置は、
    　前記端末装置の移動速度に関する制御情報を取得する取得部と、
    　前記端末装置が前記第１の基地局装置から自装置へ通信相手を変更する際に、又は前記第１の基地局装置に加えて自装置を通信相手に追加する際に、前記端末装置による既知信号の送信間隔を制御する制御部と、
    　前記制御部によって制御された送信間隔に関する制御情報を送信する送信部とを有し、
    　前記端末装置は、
    　前記第２の基地局装置から送信された制御情報を受信する受信部と、
    　既知信号の送信間隔を制御する送信間隔制御部とを有する
    　ことを特徴とする無線通信システム。     A wireless communication system having a terminal device, a first base station device, and a second base station device,
    The second base station apparatus is
    An acquisition unit for acquiring control information related to the moving speed of the terminal device;
    Known by the terminal device when the terminal device changes the communication partner from the first base station device to the own device, or when the terminal device is added to the communication partner in addition to the first base station device. A control unit for controlling a signal transmission interval;
    A transmission unit that transmits control information related to a transmission interval controlled by the control unit;
    The terminal device
    A receiving unit for receiving control information transmitted from the second base station device;
    A wireless communication system comprising: a transmission interval control unit that controls a transmission interval of a known signal.
  7. 　既知信号の送信間隔に関する制御情報を受信する受信部と、
    　既知信号の送信間隔を制御する制御部と
    　を有することを特徴とする端末装置。     A receiving unit for receiving control information related to the transmission interval of the known signal;
    And a control unit that controls a transmission interval of the known signal.
  8. 　自装置の移動速度に関する制御情報を生成する生成部をさらに有し、
    　前記制御部は、
    　自装置の移動速度に対応して既知信号の送信間隔を制御する
    　ことを特徴とする請求項７記載の端末装置。     A generator that generates control information related to the moving speed of the device itself;
    The controller is
    The terminal device according to claim 7, wherein the transmission interval of the known signal is controlled in accordance with the moving speed of the device itself.
PCT/JP2017/017760 2017-05-10 2017-05-10 Base station apparatus, terminal apparatus, transmission interval control method, and wireless communication system WO2018207297A1 (en)

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JPH0787011A (en) * 1993-09-14 1995-03-31 Toshiba Corp Radio communication system, radio equipment and switch
JP2004364167A (en) * 2003-06-06 2004-12-24 Mitsubishi Electric Corp Mobile station location detecting system, mobile station, base station and location information center
WO2009119051A1 (en) * 2008-03-26 2009-10-01 三洋電機株式会社 Communication method and radio device using the same
WO2013024586A1 (en) * 2011-08-12 2013-02-21 京セラ株式会社 Wireless communication system and wireless communication system control method
WO2016129417A1 (en) * 2015-02-09 2016-08-18 三菱電機株式会社 Communication apparatus
WO2016152114A1 (en) * 2015-03-23 2016-09-29 日本電気株式会社 Base station apparatus, communication system and communication method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0787011A (en) * 1993-09-14 1995-03-31 Toshiba Corp Radio communication system, radio equipment and switch
JP2004364167A (en) * 2003-06-06 2004-12-24 Mitsubishi Electric Corp Mobile station location detecting system, mobile station, base station and location information center
WO2009119051A1 (en) * 2008-03-26 2009-10-01 三洋電機株式会社 Communication method and radio device using the same
WO2013024586A1 (en) * 2011-08-12 2013-02-21 京セラ株式会社 Wireless communication system and wireless communication system control method
WO2016129417A1 (en) * 2015-02-09 2016-08-18 三菱電機株式会社 Communication apparatus
WO2016152114A1 (en) * 2015-03-23 2016-09-29 日本電気株式会社 Base station apparatus, communication system and communication method

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