WO2017002269A1

WO2017002269A1 - Base station, relay device, mobile-object communication system, and delay correction method

Info

Publication number: WO2017002269A1
Application number: PCT/JP2015/069199
Authority: WO
Inventors: 平野　幸男; 隆志西谷; 健一名倉
Original assignee: 三菱電機株式会社
Priority date: 2015-07-02
Filing date: 2015-07-02
Publication date: 2017-01-05
Also published as: JPWO2017002269A1; JP6362779B2

Abstract

A base station 1 connected to a plurality of relay devices is provided with as many transmission-reception units 11a to 11d as the plurality of relay devices, each transmission-reception unit being connected to and communicating with one of the relay devices. The transmission-reception units 11a to 11d are each provided with: a frame generation unit 112 that generates a downlink transmission frame; a frame end unit 116 that detects an uplink transmission frame; a delay measurement unit 113 that measures a delay occurring in a communication between the transmission-reception unit and the relay device to which the transmission-reception unit is connected, acquires information regarding a delay occurring in a communication between the relay device to which the transmission-reception unit is connected and a terminal, and information regarding a delay time allowable in a communication between the base station and the terminal, and holds the information; a downlink delay correction unit 111 that calculates a downlink delay correction time using the delay information held by the delay measurement unit 113, and delays wireless data stored in the downlink transmission frame; and an uplink delay correction unit 117 that calculates an uplink delay correction time using the delay information held by the delay measurement unit 113, and delays wireless data stored in the uplink transmission frame.

Description

Base station, repeater, mobile communication system, and delay correction method

The present invention relates to a base station, a repeater, a mobile communication system, and a delay correction method that perform wireless communication with a moving terminal.

Conventionally, in a system that performs data communication between a moving body such as a train moving on a railroad or an automobile moving on a road and ground equipment, stable communication cannot be performed when the moving body is moving at high speed. There was a problem. This is because, since the communication area of one radio base station is small, if the mobile unit moves at a high speed, the stay time of one communication area is shortened, and handovers frequently occur, thereby reducing the substantial communication time. .

As a countermeasure, in Patent Document 1, one base station transmits the same signal to a plurality of slave stations installed along a moving path of a mobile body via an optical fiber, and the plurality of slave stations transmit the same radio signal. Is disclosed that operates so that a plurality of communication areas formed by a plurality of slave stations become one communication area formed along a movement path. Thereby, the communication area which one base station can cover can be expanded. When a mobile unit transmits a signal in a place where the communication areas of each slave station overlap, the base station will have different propagation delay times for signals from each slave station if there is a difference in the optical fiber length connecting the slave station and the base station. Each other's signals interfere. As a countermeasure, Patent Document 1 includes a delay corrector that adjusts the optical fiber length to make the propagation delay time from each slave station to the base station uniform, and reduces the difference in propagation delay time.

JP 2005-191905 A

However, according to the above conventional technique, the propagation delay is made uniform by adjusting the optical fiber length. However, since the propagation delay time of the optical fiber is about 5 ns / m, communication with a data width of one symbol of 10 ns, For example, in the case of binary modulation, in the case of communication corresponding to 100 Mbps, it is necessary to adjust the optical fiber length with an accuracy of ± 2 m. Since the base station is not necessarily placed in the vicinity of the communication area, it is possible to use an optical fiber exceeding 10 km. Therefore, there has been a problem that adjustment with a high accuracy of 0.02% with respect to the entire length of the optical fiber is required. Further, according to the conventional technique, the propagation delay of the optical signal is made uniform by the optical fiber, but the propagation delay of the radio signal in the radio communication section between the slave station and the mobile body is not taken into consideration. Therefore, there is a problem that the influence of the interference wave cannot be avoided.

The present invention has been made in view of the above, and when connecting with a plurality of repeaters via an optical fiber, the length of the optical fiber between each repeater is not aligned with high accuracy, It is an object of the present invention to obtain a base station that makes the propagation delay uniform in communication with a terminal via each repeater and can avoid the influence of interference waves.

In order to solve the above-described problems and achieve the object, the base station of the present invention is connected to a plurality of relay devices that are arranged along the movement path of the terminal and performs wireless communication with the terminal, and A base station that performs communication. The base station includes the same number of transmission / reception units that communicate with each other by connecting to one repeater. Each transmission / reception unit includes a frame generation unit that generates a downlink transmission frame to be transmitted to the repeater. Each transmission / reception unit includes a frame termination unit that detects an uplink transmission frame transmitted from the repeater. Each transmitting / receiving unit measures delay generated in communication between the own transmitting / receiving unit and the relay connected to the own transmitting / receiving unit, and information on delay generated in communication between the relay connected to the own transmitting / receiving unit and the terminal. And a delay measurement unit that acquires information on a delay time allowed in communication between the base station and the terminal and holds the acquired information. Each transmission / reception unit calculates a downlink delay correction time using the delay information held by the delay measurement unit, and uses a downlink delay correction unit that delays wireless data stored in the downlink transmission frame using the downlink delay correction time. Prepare. Each transmission / reception unit calculates an uplink delay correction time using the delay information held by the delay measurement unit, and uses the uplink delay correction time to delay the radio data stored in the uplink transmission frame. It is characterized by providing.

When the base station according to the present invention is connected to a plurality of repeaters via optical fibers, the length of the optical fiber between each repeater is not adjusted with high accuracy, and the terminal passes through each repeater. In the communication with this, it is possible to make the propagation delay uniform and to avoid the influence of the interference wave.

The figure which shows the structural example of a mobile communication system. Block diagram showing configuration example of base station Block diagram showing a configuration example of a repeater Flow chart showing delay correction processing of base station The figure which shows the method in which a base station calculates the round-trip delay time between repeaters A flowchart showing the operation of the frame generation unit of the transmission / reception unit Flow chart showing the operation of the frame end of the repeater Flow chart showing the operation of the frame generator of the repeater A flowchart showing the operation of the frame termination unit of the transmission / reception unit Flowchart showing the operation of the delay measurement unit calculating the downlink one-way delay time and the uplink one-way delay time Flowchart showing the operation of the delay measurement unit calculating the radio propagation delay time difference Flowchart showing an operation in which the delay measurement unit acquires information on the designated downlink delay time and the designated uplink delay time The figure which shows the timing chart of the radio | wireless data signal until the downlink delay correction process of the transmission / reception part of a base station and a terminal receives a radio signal The flowchart which shows operation | movement of the downlink delay correction process by the downlink delay correction | amendment part of the transmission / reception part of a base station. Timing chart of radio data until the uplink delay correction processing of the base station transceiver unit and the base station selection unit receive the radio data The flowchart which shows the operation | movement of the uplink delay correction process by the uplink delay correction | amendment part of the transmission / reception part of a base station. The figure which shows the structural example of the processing circuit which implement | achieves the downlink delay correction | amendment part of the transmission / reception part of a base station, a frame production | generation part, a delay measurement part, a frame termination | terminus part, and an uplink delay correction | amendment part

Hereinafter, a base station, a repeater, a mobile communication system, and a delay correction method according to an embodiment of the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram showing a configuration example of a mobile communication system 7 according to an embodiment of the present invention. The mobile communication system 7 includes a base station 1 that is a master station and

repeaters

2a, 2b, 2c, and 2d that are slave stations. The base station 1 is connected to the

repeaters

2a, 2b, 2c, 2d via

optical fibers

3a, 3b, 3c, 3d. The base station 1 communicates with a terminal 4 that is a moving body via optical fibers 3a to 3d and repeaters 2a to 2d. Relay units 2 a to 2 d arranged along the movement path of terminal 4 relay communication between base station 1 and terminal 4. The repeaters 2a to 2d perform optical communication with the base station 1 through the optical fibers 3a to 3d, and perform wireless communication with the terminal 4. In the mobile communication system 7, the terminal 4 moves on a known moving route in advance, such as a train moving on a track or an automobile moving on a road.

The relay machine 2a communicates with the terminal 4 within the communication area 5a. The repeater 2b communicates with the terminal 4 within the communication area 5b. The repeater 2c communicates with the terminal 4 within the communication area 5c. The repeater 2d communicates with the terminal 4 within the communication area 5d. The interference area 6ab is an area where the communication area 5a and the communication area 5b overlap with each other, and the

repeaters

2a and 2b can communicate with the terminal 4. The interference area 6bc is an area where the communication area 5b and the communication area 5c overlap with each other, and the repeaters 2b and 2c can communicate with the terminal 4. The interference area 6cd is an area in which the communication area 5c and the communication area 5d overlap with each other, and is an area where the repeaters 2c and 2d can communicate with the terminal 4. The mobile communication system 7 can provide a wide linear communication area to the terminal 4 by using a plurality of relay units 2a to 2d.

In FIG. 1, the repeaters 2a to 2d include an antenna 25. In the following description, when the relay devices 2a to 2d are not distinguished, they are referred to as the relay device 2, when the optical fibers 3a to 3d are not distinguished, they are referred to as the optical fiber 3, and when the communication areas 5a to 5d are not distinguished, the communication area 5 is referred to. When the interference areas 6ab, 6bc, and 6cd are not distinguished, they are referred to as the interference area 6.

FIG. 2 is a block diagram showing a configuration example of the base station 1 according to the present embodiment. The base station 1 includes transmission /

reception units

11a, 11b, 11c, and 11d, a modulation unit 12, a demodulation unit 13, and a selection unit 14. In addition, the transmission / reception units 11a to 11d respectively include a downlink delay correction unit 111, a frame generation unit 112, a delay measurement unit 113, an E / O (Electrical to Optical) unit 114, and an O / E (Optical to Electrical). Unit 115, frame termination unit 116, and uplink delay correction unit 117. Although omitted in FIG. 2, it is assumed that the transmission / reception units 11b to 11d have the same configuration as the transmission / reception unit 11a. The base station 1 includes the same number of transmission / reception units 11a to 11d as the repeaters 2a to 2d. The transmission / reception units 11a to 11d are each connected to one repeater 2. Specifically, the transmitter / receiver 11a is connected to the repeater 2a via the optical fiber 3a, the transmitter / receiver 11b is connected to the repeater 2b via the optical fiber 3b, and the transmitter / receiver 11c is connected to the repeater via the optical fiber 3c. The transmitter / receiver 11d is connected to the repeater 2d via the optical fiber 3d. In the following description, when the transmission / reception units 11a to 11d are not distinguished, they are referred to as the transmission / reception unit 11. Each transmitting / receiving unit 11 and each repeater 2 are connected in a one-to-one correspondence.

The modulation unit 12 generates digitized wireless data and outputs it to the transmission / reception units 11a to 11d. The demodulator 13 demodulates the radio data input from the selector 14. The modulation unit 12 and the demodulation unit 13 are configured by a modem, for example.

The selection unit 14 outputs the wireless data input from the transmission / reception units 11a to 11d to the demodulation unit 13. When wireless data is input from a plurality of transmission / reception units 11 among the transmission / reception units 11a to 11d, the selection unit 14 may select and output one wireless data, or may combine and output a plurality of wireless data. May be. The selection unit 14 is configured by, for example, a switch circuit or a synthesis circuit.

The transmission / reception units 11a to 11d perform a downlink delay correction process on the radio data input from the modulation unit 12, convert a transmission frame including the radio data from an electric signal to an optical signal, and repeaters via the optical fibers 3a to 3d Send to 2a-2d. Further, the transmission / reception units 11a to 11d convert optical signals received from the repeaters 2a to 2d through the optical fibers 3a to 3d into electric signals, and perform uplink delay correction processing on the wireless data extracted from the detected transmission frames. To the selection unit 14.

The downlink delay correction unit 111 performs downlink delay correction processing on the wireless data input from the modulation unit 12 and outputs the result to the frame generation unit 112. The downlink delay correction unit 111 calculates the downlink delay correction time using the delay information held by the delay measurement unit 113, and uses the downlink delay correction time to convert the radio data stored in the downlink RoF (Radio on Fiber) frame. Delay. The downlink RoF frame is a downlink transmission frame used in wireless communication using an optical fiber as a part of a communication path. Detailed operation will be described later.

The frame generation unit 112 generates a downlink RoF frame to be transmitted to the relay device 2 and outputs it to the E / O unit 114. The downlink RoF frame is composed of a synchronization pattern, a header, and a payload. When the wireless data is input from the downlink delay correction unit 111, the frame generation unit 112 stores the wireless data in the payload of the downlink RoF frame.

The delay measuring unit 113 measures a round trip time RTT (Round Trip Time) from the transmission of the downlink RoF frame from the transmission / reception unit 11 to the reception of the uplink RoF frame from the repeater 2. The uplink RoF frame is an uplink transmission frame used in wireless communication using an optical fiber as a part of the communication path. The delay measurement unit 113 measures the delay generated in communication between the transmission / reception unit 11 and the relay 2 connected to the transmission / reception unit 11, thereby generating the communication between the transmission / reception unit 11 and the relay 2 connected to the transmission / reception unit 11. Information on the delay to be transmitted, information on the delay generated in the communication between the repeater 2 connected to the transmitter / receiver 11 and the terminal 4, and information on the delay time allowed in the communication between the base station 1 and the terminal 4 And retain the acquired information. Detailed operation will be described later.

The E / O unit 114 converts the downlink RoF frame of the electrical signal input from the frame generation unit 112 into an optical signal and transmits the optical signal to the repeater 2. The E / O unit 114 is configured by, for example, an electro-optical conversion circuit.

The O / E unit 115 converts the optical signal received from the repeater 2 into an electrical signal and outputs the electrical signal to the frame termination unit 116. The O / E unit 115 is configured by, for example, a photoelectric conversion circuit.

The frame termination unit 116 detects an uplink RoF frame by detecting a synchronization pattern from the electrical signal. In addition, the frame termination unit 116 confirms the header of the uplink RoF frame, extracts radio data when the radio data is stored in the payload of the uplink RoF frame, and outputs the radio data to the uplink delay correction unit 117.

The uplink delay correction unit 117 performs an uplink delay correction process on the radio data input from the frame termination unit 116 and outputs the result to the selection unit 14. The uplink delay correction unit 117 calculates the uplink delay correction time using the delay information held by the delay measurement unit 113, and delays the radio data stored in the uplink RoF frame using the uplink delay correction time. Detailed operation will be described later.

FIG. 3 is a block diagram showing a configuration example of the repeater 2a according to the present embodiment. Since the repeaters 2a to 2d have the same configuration, the repeater 2a will be described as an example. The repeater 2a includes an O / E unit 21, a frame termination unit 22, a D / A (Digital to Analog) unit 23, an RF (Radio Frequency) transmission front end 24, an antenna 25, and an RF reception front end 26. And an A / D (Analog to Digital) unit 27, a frame generation unit 28, and an E / O unit 29.

The O / E unit 21 converts the optical signal received from the base station 1 into an electrical signal and outputs the electrical signal to the frame termination unit 22. The O / E unit 21 is configured by, for example, a photoelectric conversion circuit.

The frame termination unit 22 detects the downlink RoF frame by detecting the synchronization pattern from the electric signal. Also, the frame termination unit 22 confirms the header of the downlink RoF frame, and if the wireless data is included in the payload of the downlink RoF frame, extracts the radio data and outputs it to the D / A unit 23. Further, the frame termination unit 22 notifies the frame generation unit 28 of the timing at which the synchronization pattern of the downlink RoF frame transmitted from the base station 1 is detected.

The D / A unit 23 converts the digital signal wireless data into analog signal wireless data. The D / A unit 23 is configured by, for example, a digital / analog conversion circuit.

The RF transmission front end 24 performs processing such as encoding and modulation on the wireless data of the analog signal, generates a wireless signal that is a signal in the wireless communication section of the wireless data, and wirelessly transmits to the communication area via the antenna 25. Radiates a signal. The RF transmission front end 24 is constituted by an interface card for wireless signal transmission, for example.

The antenna 25 transmits and receives radio signals to and from the terminal 4. The antenna 25 is configured by a directional antenna element, for example.

The RF reception front end 26 outputs to the A / D unit 27 wireless data obtained by performing processing such as demodulation and decoding on the wireless signal received via the antenna 25. The RF reception front end 26 is configured by, for example, an interface card for wireless signal reception.

The A / D unit 27 converts the wireless data of the analog signal into the wireless data of the digital signal. The A / D unit 27 is configured by an analog-digital conversion circuit, for example.

The frame generation unit 28 generates an uplink RoF frame composed of a synchronization pattern, a header, and a payload, and outputs it to the E / O unit 29. When the wireless data is input from the A / D unit 27, the frame generation unit 28 stores the wireless data in the payload of the uplink RoF frame. Further, the frame generation unit 28 generates an uplink RoF frame at the timing notified from the frame termination unit 22.

The E / O unit 29 converts the uplink RoF frame of the electrical signal input from the frame generation unit 28 into an optical signal and transmits it to the base station 1. The E / O unit 29 is configured by, for example, an electro-optical conversion circuit.

Next, a description will be given of a downlink delay correction process when the base station 1 transmits wireless data to the repeaters 2a to 2d and an uplink delay correction process when wireless data is received from the repeaters 2a to 2d. FIG. 4 is a flowchart showing the delay correction process of the base station 1 according to this embodiment. First, each of the delay measurement units 113 of the transmission / reception units 11a to 11d of the base station 1 performs downlink delay correction times DTa to DTd for radio data transmitted to the repeaters 2a to 2d in the downlink delay correction processing and the uplink delay correction processing, and Delay information necessary to calculate the uplink delay correction times UTa to UTd for the radio data received from the repeaters 2a to 2d is acquired (step S1).

The delay information necessary for calculating the downlink delay correction times DTa to DTd and the uplink delay correction times UTa to UTd includes the downlink one-way delay times DLa to DLd, the uplink one-way delay times ULa to ULd, the radio propagation delay time difference, and the designated downlink Delay time Ddn and designated upstream delay time Dup. The downlink one-way delay times DLa to DLd are delay times generated in downlink communication from the transmission / reception units 11a to 11d to the repeaters 2a to 2d. Upward one-way delay times ULa to ULd are delay times generated in upstream communication from the repeaters 2a to 2d to the transmission / reception units 11a to 11d. The difference in radio propagation delay time is the difference between the radio propagation delay time when a radio signal is transmitted from a certain relay station 2 to the terminal 4 and the radio propagation delay time when a radio signal is transmitted from the reference relay station 2 to the terminal 4 It is. The designated downlink delay time Ddn is a time allowed for downlink communication from the base station 1 to the terminal 4. The designated uplink delay time Dup is a time allowed for uplink communication from the terminal 4 to the base station 1.

First, in the processing of step S1 shown in the flowchart of FIG. 4, the delay measurement unit 113 of the transmission / reception units 11a to 11d of the base station 1 calculates the downlink one-way delay times DLa to DLd and the uplink one-way delay times ULa to ULd. An operation for measuring the round-trip delay times RTTa to RTTd between the repeaters 2a to 2d necessary for the above will be described. As an example, a case will be described in which the delay measurement unit 113 of the transmission / reception unit 11a of the base station 1 measures the round-trip delay time RTTa between the transmission / reception unit 11a and the repeater 2a connected to the transmission / reception unit 11a. Note that the delay measurement unit 113 of the transmission / reception units 11b to 11d measures the round trip delay times RTTb to RTTd with the repeaters 2b to 2d by the same method. FIG. 5 is a diagram illustrating a method in which the base station 1 according to the present embodiment calculates the round-trip delay time RTTa with the repeater 2a.

In the transmission / reception unit 11a of the base station 1, the frame generation unit 112 generates a downlink RoF frame. As shown in FIG. 5, the frame generation unit 112 generates a downlink RoF frame composed of a synchronization pattern of a known bit arrangement located at the head, a header that stores a control signal, and a payload that stores wireless data. Generate. Here, the frame generation unit 112 does not include valid wireless data in the payload. FIG. 6 is a flowchart showing the operation of the frame generation unit 112 of the transmission / reception unit 11a according to this embodiment. When generating the downlink RoF frame (step S11), the frame generation unit 112 notifies the delay measurement unit 113 of the start timing of the synchronization pattern of the generated downlink RoF frame (step S12). The delay measurement unit 113 stores the timing notified from the frame generation unit 112. The frame generation unit 112 outputs the generated downlink RoF frame to the E / O unit 114. The E / O unit 114 converts the downlink RoF frame generated by the frame generation unit 112 into an optical signal and transmits the optical signal to the repeater 2a via the optical fiber 3a.

As shown in FIG. 5, the repeater 2a receives the downstream RoF frame of the optical signal delayed from the transmission delay by the optical fiber 3a after being transmitted from the base station 1. In the repeater 2a, the O / E unit 21 converts the optical signal received from the base station 1 through the optical fiber 3a into an electrical signal and outputs the electrical signal to the frame termination unit 22. FIG. 7 is a flowchart showing the operation of the frame termination unit 22 of the repeater 2a according to this embodiment. The frame termination unit 22 detects a downlink RoF frame starting from the synchronization pattern by detecting a synchronization pattern having a known bit arrangement from the electrical signal (step S21). The frame end unit 22 notifies the frame generation unit 28 of the timing at which the synchronization pattern of the downlink RoF frame is detected (step S22). FIG. 8 is a flowchart showing the operation of the frame generation unit 28 of the repeater 2a according to the present embodiment. The frame generation unit 28 receives a notification of the detection timing of the synchronization pattern of the downlink RoF frame from the frame end unit 22 (step S31). The frame generation unit 28, in synchronization with the detection timing of the synchronization pattern of the downlink RoF frame, starts with the notified detection timing, a synchronization pattern of a known bit arrangement located at the head, a header storing a control signal, a wireless An uplink RoF frame composed of a payload for storing data is generated (step S 32) and output to the E / O unit 29. The E / O unit 29 converts the uplink RoF frame generated by the frame generation unit 28 into an optical signal and transmits the optical signal to the base station 1 via the optical fiber 3a.

As shown in FIG. 5, the base station 1 receives the upstream RoF frame of the optical signal after being transmitted from the repeater 2a and delayed by the propagation delay by the optical fiber 3a. In the transmission / reception unit 11 a of the base station 1, the O / E unit 115 converts the optical signal received from the repeater 2 a through the optical fiber 3 a into an electrical signal and outputs the electrical signal to the frame termination unit 116. FIG. 9 is a flowchart showing the operation of the frame termination unit 116 of the transmission / reception unit 11a according to the present embodiment. The frame termination unit 116 detects an uplink RoF frame starting from the synchronization pattern by detecting a synchronization pattern having a known bit arrangement from the electrical signal (step S41). The frame termination unit 116 notifies the delay measurement unit 113 of the timing at which the synchronization pattern of the uplink RoF frame is detected (step S42).

FIG. 10 is a flowchart showing an operation in which the delay measurement unit 113 according to the present embodiment calculates the downlink one-way delay time DL and the uplink one-way delay time UL. The delay measurement unit 113 receives a notification of the start timing of the synchronization pattern of the downlink RoF frame from the frame generation unit 112 (step S51), and receives a notification of the detection timing of the synchronization pattern of the uplink RoF frame from the frame termination unit 116 (step S52). ). The delay measurement unit 113 determines the round-trip delay time between the transmission / reception unit 11a and the repeater 2a connected to the transmission / reception unit 11a from the difference between the detection timing of the synchronization pattern of the uplink RoF frame and the start timing of the synchronization pattern of the downlink RoF frame. RTTa is calculated (step S53). Also, the delay measuring unit 113 calculates a downlink one-way delay time DLa, which is a delay time of radio data transmitted from the base station 1 to the repeater 2a, from the calculated round-trip delay time RTTa (step S54), and repeater 2a. The uplink one-way delay time ULa, which is the delay time of the wireless data transmitted from to the base station 1, is calculated (step S55). Note that “round trip delay time RTTa = downward one-way delay time DLa + upward one-way delay time ULa”.

For example, when the optical fiber 3a is composed of two core wires and the optical wavelengths used by the base station 1 and the repeater 2a are the same, the delay measuring unit 113 is configured so that the downlink one-way delay time DLa and the uplink one-way delay time ULa are round-trip delays. It can be calculated as 1/2 of the time RTTa.

In addition, the delay measurement unit 113 includes, for example, an optical fiber 3a formed of a single core, and uses a WDM (Wavelength Division Multiplex) coupler to make the transmission wavelength of the base station 1 different from the transmission wavelength of the repeater 2a. ITU (International Telecommunication Union) -T G. 984.3 Figure VII. As shown in FIG. 1, it is possible to calculate the downlink one-way delay time DLa and the uplink one-way delay time ULa by multiplying the round-trip delay time RTTa by a value including propagation delays that differ depending on the uplink and downlink wavelengths. The value that takes into account propagation delays that differ depending on the upstream and downstream wavelengths is a value close to ½.

Similarly, in the base station 1, the delay measurement unit 113 of the transmission / reception unit 11b calculates the round trip delay time RTTb between the transmission / reception unit 11b and the repeater 2b, and the downlink one-way delay time DLb and the uplink one-way delay time ULb. Is calculated. In addition, the delay measurement unit 113 of the transmission / reception unit 11c calculates the round trip delay time RTTc between the transmission / reception unit 11c and the repeater 2c, and calculates the downlink one-way delay time DLc and the uplink one-way delay time ULc. In addition, the delay measurement unit 113 of the transmission / reception unit 11d calculates a round trip delay time RTTd between the transmission / reception unit 11d and the repeater 2d, and calculates a downlink one-way delay time DLd and an uplink one-way delay time ULd.

Next, an operation in which the delay measurement units 113 of the transmission / reception units 11a to 11d of the base station 1 calculate the radio propagation delay time difference in the process of step S1 shown in the flowchart of FIG. 4 will be described. FIG. 11 is a flowchart showing an operation in which the delay measurement unit 113 according to the present embodiment calculates the radio propagation delay time difference. Here, the operation in which the delay measurement unit 113 of the transmission / reception unit 11b calculates the radio propagation delay time difference Dba of the repeater 2b with reference to the repeater 2a in FIG. 1 will be described. The radio propagation delay time difference Dba is the difference between the radio propagation delay time of the radio signal from the repeater 2b to the terminal 4 connected to the transceiver 11b and the radio propagation delay time of the radio signal from the reference repeater 2a to the terminal 4. It is a difference. The delay measurement unit 113 of the transmission / reception unit 11b receives input of information from an operator of the mobile communication system 7 and acquires the positional information of the relay device 2a and the relay device 2b (step S61).

The delay measurement unit 113 of the transmission / reception unit 11b assumes, for example, that the terminal 4 is at the center of the interference area 6ab of the communication area 5a of the relay 2a and the communication area 5b of the relay 2b, and the center of the interference area 6ab. Get location information. The delay measurement unit 113 of the transmission / reception unit 11b may acquire the position information of the center of the interference area 6ab by receiving input of information from an operator of the mobile communication system 7 or the like, or the

relay units

2a and 2b. You may calculate based on the positional information and the information on the movement route of the terminal 4. The delay measuring unit 113 of the transmission / reception unit 11b uses the position information of the

relays

2a and 2b and the information on the center position of the interference area 6ab to determine the distance Laba between the relay 2a and the center position of the interference area 6ab and the relay 2b. A distance Labb from the center position of the interference area 6ab is calculated (step S62).

When the terminal 4 is in the center of the interference area 6ab, when the relay 2a is used as a reference, the propagation time until the wireless signal transmitted from the relay 2a reaches the terminal 4 and the wireless signal transmitted from the relay 2b are A radio propagation delay time difference Dba, which is a difference from the propagation time until the terminal 4 is reached, can be expressed by Expression (1). Where c is the speed of light in the air. The radio propagation delay time Dba can take either positive or negative sign. The delay measurement unit 113 of the transmission / reception unit 11b calculates the radio propagation delay time difference Dba from the equation (1) (step S63).

Dba = (Labb-Laba) / c (1)

Similarly, when the delay measurement unit 113 of the transmission / reception unit 11c of the base station 1 acquires the position information of the repeaters 2b and 2c, the delay measurement unit 113 of the communication area 5b of the repeater 2b and the interference area 6bc of the communication area 5c of the repeater 2c. The distances Lbcb and Lbcc with respect to the repeaters 2b and 2c with respect to the central terminal 4 are calculated, and the radio propagation delay time difference Dcb of the repeater 2c with respect to the repeater 2b is calculated. In addition, when the delay measuring unit 113 of the transmission / reception unit 11d of the base station 1 acquires the position information of the repeaters 2c and 2d, the center of the interference area 6cd of the communication area 5c of the repeater 2c and the communication area 5d of the repeater 2d. The distances Lcdc and Lcdd between the terminal 4 and the relays 2c and 2d are calculated, and the radio propagation delay time difference Ddc of the relay 2d with respect to the relay 2c is calculated. In addition, since the interference area 6 is not affected by the influence of the non-adjacent repeater 2, that is, interference, the radio propagation delay times Dba, Dcb, and Ddc have no correlation.

Here, the repeaters 2a to 2d communicate with the terminal 4 using the antenna 25 having high directivity. Specifically, in the example of FIG. 1, the terminal 4 is used using the antenna 25 having high directivity in the left direction. When the communication is performed, the radio propagation delay time difference can be obtained from the distance information between the repeaters 2 along the communication area 5. In this case, the radio propagation delay time differences Dba, Dca, Dda can be calculated using the above-described equation (1) with the repeater 2a as a reference. “Dca = Dcb + Dba” and “Dda = Ddc + Dcb + Dba”. That is, the delay measurement unit 113 of the transmission / reception units 11a to 11d uses the position information of the relay 2 connected to each transmission / reception unit 11 and the reference relay 2 to connect the relay 2 connected to each transmission / reception unit 11. A radio propagation delay time difference that is a difference between the radio propagation delay time of the radio signal from the terminal 4 to the terminal 4 and the radio propagation delay time of the radio signal from the reference relay 2 to the terminal 4 can be calculated. Specifically, the delay measuring unit 113 of the transmission / reception unit 11d uses the position information of the relay 2d connected to the transmission / reception unit 11d and the reference relay 2a to the terminal 4 from the relay 2d connected to the transmission / reception unit 11d. The radio propagation delay time difference Dda, which is the difference between the radio propagation delay time of the radio signal and the radio propagation delay time of the radio signal from the reference relay 2a to the terminal 4, can be calculated.

In the mobile communication system 7, when the repeaters 2a to 2d are installed, the positional relationship and distance of each repeater 2 do not change. For this reason, the base station 1 does not calculate the information on each radio propagation delay time difference, and the operator of the mobile communication system 7 calculates each radio propagation delay time difference when installing the repeaters 2a to 2d. Information on each radio propagation delay time difference may be set in the delay correction unit 113 of each of the transmission / reception units 11a to 11d. Even when the operator of the mobile communication system 7 calculates each radio propagation delay time difference, the above equation (1) is used for the calculation.

Next, in the process of step S1 shown in the flowchart of FIG. 4, each delay measurement unit 113 of the transmission / reception units 11a to 11d of the base station 1 acquires information on the designated downlink delay time Ddn and the designated uplink delay time Dup. FIG. 12 is a flowchart showing an operation in which the delay measurement unit 113 according to the present embodiment acquires information on the designated downlink delay time Ddn and the designated uplink delay time Dup. Each of the delay measurement units 113 of the transmission / reception units 11a to 11d of the base station 1 has a specified downlink delay time Ddn allowed in the downlink communication of the mobile communication system 7 according to the setting of the operator of the mobile communication system 7 or the like. Information is acquired (step S71), and information on the designated uplink delay time Dup allowed in the uplink communication of the mobile communication system 7 is acquired (step S72). The designated downlink delay time Ddn can be, for example, the maximum downlink delay time allowed in the mobile communication system 7, but is not limited thereto. The designated uplink delay time Dup can be, for example, the maximum delay time in the uplink direction allowed in the mobile communication system 7, but is not limited thereto.

As described above, the delay measurement unit 113 of the transmission / reception units 11a to 11d of the base station 1 completes the process of step S1 shown in FIG.

Returning to the flowchart of FIG. The base station 1 performs delay correction processing by calculating the delay correction time used in downlink and uplink communication using the delay information acquired in the process of step S1. First, downlink delay correction processing in downlink communication will be described.

The base station 1 calculates downlink delay correction times DTa to DTd in the downlink direction when wireless data is transmitted to the terminal 4 via the repeaters 2a to 2d (step S2).

The base station 1 uses the designated downlink delay time Ddn, radio propagation delay time differences Ddc, Dcb, Dba, and downlink one-way delay times DLa to DLd acquired in the process of step S1, to calculate the downlink delay correction times DTa to DTd. calculate.

Specifically, the downlink delay correction unit 111 of the transmission / reception unit 11a of the base station 1 stores the delay information acquired in the process of step S1 held in the delay measurement unit 113, that is, the specified downlink delay time Ddn, and the downlink piece. Using the direction delay time DLa, the downlink delay correction time DTa for the radio data to be transmitted to the repeater 2a is calculated from Equation (2).

DTa = Ddn-DLa (2)

Further, the downlink delay correction unit 111 of the transmission / reception unit 11b of the base station 1 stores the delay information acquired in the processing of step S1 held in the delay measurement unit 113, that is, the specified downlink delay time Ddn and the radio propagation delay time difference Dba. , And the downlink one-way delay time DLb, the downlink delay correction time DTb for the radio data transmitted to the repeater 2b is calculated from Equation (3).

DTb = Ddn-DLb-Dba (3)

Further, the downlink delay correction unit 111 of the transmission / reception unit 11c of the base station 1 stores the delay information acquired in the processing of the above-described step S1 held in the delay measurement unit 113, that is, the designated downlink delay time Ddn and the radio propagation delay time Dcb. , Dba and the downlink one-way delay time DLc, the downlink delay correction time DTc for the radio data transmitted to the repeater 2c is calculated from the equation (4). Note that Expression (4) can be expressed as Expression (4 ′).

DTc = Ddn-DLc-Dcb-Dba (4)
DTc = Ddn−DLc−Dca (4 ′)

Further, the downlink delay correction unit 111 of the transmission / reception unit 11d of the base station 1 stores the delay information acquired in the processing of step S1 held in the delay measurement unit 113, that is, the specified downlink delay time Ddn and the radio propagation delay time difference Ddc. , Dcb, Dba and the downlink one-way delay time DLd, the downlink delay correction time DTd for the radio data transmitted to the repeater 2d is calculated from the equation (5). Note that Expression (5) can be expressed as Expression (5 ′).

DTd = Ddn-DLd-Ddc-Dcb-Dba (5)
DTd = Ddn−DLd−Dda (5 ′)

Specifically, the downlink delay correction processing in the transmission / reception unit 11 when the base station 1 transmits wireless data to the terminal 4 will be described. FIG. 13 is a diagram illustrating a downlink delay correction process of the transmission /

reception units

11a and 11b of the base station 1 according to the present embodiment and a timing chart of radio data until the terminal 4 receives a radio signal. Here, the operations of the

transceiver units

11a and 11b, the

repeaters

2a and 2b, and the terminal 4 of the base station 1 will be mainly described.

First, the modulation unit 12 of the base station 1 generates radio data digitized for the terminal 4 and distributes the same radio data to the transmission / reception units 11a to 11d.

In the transmission / reception unit 11a, the downlink delay correction unit 111 performs a downlink delay correction process in which the delay of the downlink delay correction time DTa calculated from the equation (2) is added to the wireless data received from the modulation unit 12 (step S3). The downlink delay correction unit 111 delays the radio data by the downlink delay correction time DTa and outputs the delayed data to the frame generation unit 112. The frame generation unit 112 stores the wireless data subjected to the downlink delay correction processing by the downlink delay correction unit 111 in the payload of the downlink RoF frame, stores a control signal including information on the storage position of the payload in the header, and outputs it. The E / O unit 113 converts the downlink RoF frame into an optical signal and transmits the optical signal to the repeater 2a through the optical fiber 3a.

Similarly, in the transmission / reception unit 11b, the downlink delay correction unit 111 performs a downlink delay correction process in which the delay of the downlink delay correction time DTb calculated by the equation (3) is added to the wireless data received from the modulation unit 12 (step) S3). The downlink delay correction unit 111 delays the wireless data by the downlink delay correction time DTb and outputs the data to the frame generation unit 112. The frame generation unit 112 stores the wireless data subjected to the downlink delay correction processing by the delay correction unit 111 in the payload of the downlink RoF frame, stores a control signal including information on the storage position of the payload in the header, and outputs it. The E / O unit 113 converts the downstream RoF frame into an optical signal and transmits the optical signal to the repeater 2b via the optical fiber 3b.

The base station 1 transmits wireless data having different delay correction times from the transmission /

reception units

11a and 11b via the

optical fibers

3a and 3b having different lengths.

The repeater 2a transmits the downlink RoF frame delayed by the downlink one-way delay time DLa from the transmission timing of the transmission / reception unit 11a, that is, the downlink one-way delay time DLa subjected to the downlink delay correction processing by the downlink delay correction unit 111 of the transmission / reception unit 11a. The downlink RoF frame in which the delay is canceled is received. The O / E unit 21 of the repeater 2a converts the received optical signal into an electrical signal. The frame termination unit 22 detects a downlink RoF frame by detecting a synchronization pattern from the electrical signal, and extracts wireless data based on control information stored in the header. The D / A unit 23 converts the wireless data of the digital signal into the wireless data of the analog signal. The RF transmission front end 24 performs processing such as encoding and modulation on the wireless data of the analog signal to generate a wireless signal, and radiates the wireless signal from the antenna 25.

Further, the repeater 2b receives the downlink RoF frame delayed by the downlink one-way delay time DLb from the transmission timing of the transmission / reception unit 11b, that is, the downlink one-way delay subjected to the downlink delay correction processing by the downlink delay correction unit 111 of the transmission / reception unit 11b. A downlink RoF frame in which the delay of time DLb is canceled is received. The O / E unit 21 of the repeater 2b converts the received optical signal into an electrical signal. The frame termination unit 22 detects a downlink RoF frame by detecting a synchronization pattern from the electrical signal, and extracts wireless data based on control information stored in the header. The D / A unit 23 converts the wireless data of the digital signal into the wireless data of the analog signal. The RF transmission front end 24 performs processing such as encoding and modulation on the wireless data of the analog signal to generate a wireless signal, and radiates the wireless signal from the antenna 25.

In FIG. 13, the timing at which the repeater 2a and the repeater 2b radiate radio signals is earlier in the repeater 2b than in the repeater 2a by the radio propagation delay time Dba, which is a positive value.

Here, when the terminal 4 is in the center of the interference area 6ab between the repeater 2a and the repeater 2b, the transmission distance from the terminal 4 to the antenna 25 of the repeater 2a and the propagation from the terminal 4 to the antenna 25 of the repeater 2b. There is a difference in distance. However, the repeater 2b radiates the radio signal with the timing advanced by the radio propagation delay time Dba calculated in consideration of the difference between the distances of the

repeaters

2a and 2b to the terminal 4. Therefore, the timing at which the radio signal radiated from the repeater 2b arrives at the terminal 4 via the radio communication section (2b → 4) is the timing at which the radio signal radiated from the repeater 2a passes through the radio communication section (2a → 4). Thus, it becomes equal to the timing of arrival at the terminal 4. The wireless communication section (2b → 4) indicates the wireless communication section from the relay station 2b to the terminal 4, and the wireless communication section (2a → 4) indicates the wireless communication section from the relay station 2a to the terminal 4. . Further, when the antenna 25 of the repeater 2a and the repeater 2b is a highly directional antenna, the difference in the propagation distance of the wireless communication section does not change in the terminal 4 even if it is off the center of the interference area 6ab. The timings at which radio signals arrive from 2a and repeater 2b are equal.

The same applies when the terminal 4 is in the interference area 6bc between the repeater 2b and the repeater 2c or in the interference area 6cd between the repeater 2c and the repeater 2d. In the base station 1, the downlink delay correction unit 111 of the transmission / reception unit 11b adds the downlink delay correction time DTb to perform the downlink delay correction process, and the downlink delay correction unit 111 of the transmission / reception unit 11c adds the downlink delay correction time DTc. The downlink delay correction process is performed, and the downlink delay correction unit 111 of the transmission / reception unit 11d adds the downlink delay correction time DTd to perform the downlink delay correction process. As a result, in the terminal 4, the arrival timing of the radio signal from the adjacent repeater 2 becomes equal. Specifically, the delay is aligned from the adjacent repeater 2 after the “designated downlink delay time Ddn + propagation time of the radio communication section (2b → 4)” has elapsed since the modulation unit 12 of the base station 1 delivered to the terminal 4 Radio signal arrives in the state.

Actually, the distance between the antenna 25 of the repeaters 2a to 2d and the terminal 4 is not 0 even at the shortest distance. Therefore, when calculating the radio propagation delay time, it is necessary to consider the shortest distance between the terminal 4 and the antenna 25 of the repeater 2. In this case, for example, it is possible to cope by changing the value of the specified downlink delay time Ddn.

FIG. 14 is a flowchart showing the operation of the downlink delay correction processing by the downlink delay correction unit 111 of the transmission / reception unit 11 of the base station 1 according to the present embodiment. When the downlink delay correction unit 111 acquires the delay information held by the delay measurement unit 113 (step S81), the downlink delay correction unit 111 calculates the downlink delay correction time using the acquired delay information (step S82), and converts the wireless data into the downlink delay correction time. Downward delay correction processing is performed to delay by only (step S83).

Returning to the flowchart of FIG. Next, an uplink delay correction process in uplink communication will be described.

The base station 1 calculates uplink delay correction times UTa to UTd in the uplink direction when wireless data is received from the terminal 4 via the repeaters 2a to 2d (step S4).

The base station 1 uses the designated uplink delay time Dup, the radio propagation delay time differences Ddc, Dcb, Dba, and the uplink one-way delay times ULa to ULd acquired in the process of step S1, to calculate the uplink delay correction times UTa to UTd. calculate.

Specifically, the uplink delay correction unit 117 of the transmission / reception unit 11a of the base station 1 stores the delay information acquired in the process of step S1 held in the delay measurement unit 113, that is, the designated uplink delay time Dup and the uplink piece. Using the direction delay time ULa, an uplink delay correction time UTa for the radio data output to the selection unit 14 is calculated from Equation (6).

UTa = Dup-ULa (6)

Further, the uplink delay correction unit 117 of the transmission / reception unit 11b of the base station 1 stores the delay information acquired in the process of step S1 held in the delay measurement unit 113, that is, the designated uplink delay time Dup and the radio propagation delay time difference Dba. , And the upstream one-way delay time ULb, the upstream delay correction time UTb for the wireless data output to the selection unit 14 is calculated from Equation (7).

UTb = Dup-ULb-Dba (7)

The uplink delay correction unit 117 of the transmission / reception unit 11c of the base station 1 also stores the delay information acquired in the above-described step S1 held in the delay measurement unit 113, that is, the designated uplink delay time Dup and the radio propagation delay time Dcb. , Dba, and upstream one-way delay time ULc, the upstream delay correction time UTc for the wireless data output to the selection unit 14 is calculated from equation (8). Note that Expression (8) can be expressed as Expression (8 ′).

UTc = Dup-ULc-Dcb-Dba (8)
UTc = Dup-ULc-Dca (8 ')

Further, the uplink delay correction unit 117 of the transmission / reception unit 11d of the base station 1 stores the delay information acquired in the process of step S1 held in the delay measurement unit 113, that is, the designated uplink delay time Dup and the radio propagation delay time difference Ddc. , Dcb, Dba, and upstream one-way delay time ULd, the upstream delay correction time UTd for the wireless data output to the selection unit 14 is calculated from Equation (9). Note that Expression (9) can be expressed as Expression (9 ′).

UTd = Dup-ULd-Ddc-Dcb-Dba (9)
UTd = Dup-ULd-Dda (9 ')

Specifically, an uplink delay correction process in the transmission / reception unit 11 when the base station 1 receives wireless data from the terminal 4 will be described. FIG. 15 is a diagram illustrating a timing chart of radio data until the uplink delay correction processing of the transmission /

reception units

11a and 11b of the base station 1 according to the present embodiment and the selection unit 14 of the base station 1 receive the radio data. . Here, the operation of the transmission /

reception units

11a and 11b of the base station 1, the

repeaters

2a and 2b, and the terminal 4 when the terminal 4 transmits a radio signal to the

repeaters

2a and 2b will be mainly described.

First, the terminal 4 transmits a radio signal addressed to the base station 1 to the

repeaters

2a and 2b. Both repeater 2a and repeater 2b receive radio signals with a delay from the transmission timing of terminal 4. In FIG. 15, the timing at which the radio signal transmitted from the terminal 4 arrives at the repeater 2a via the radio communication section (4 → 2a) is the same as the timing when the radio signal transmitted from the terminal 4 passes through the radio communication section (4 → 2b). It is earlier than the timing of arrival at the relay station 2b via the radio propagation delay time Dba, which is a positive value calculated in consideration of the difference between the distances of the

relay stations

2a and 2b to the terminal 4. The wireless communication section (4 → 2a) indicates the wireless communication section from the terminal 4 to the relay 2a, and the wireless communication section (4 → 2b) indicates the wireless communication section from the terminal 4 to the relay 2b. .

In the repeater 2a, the RF reception front end 26 performs processing such as demodulation and decoding on the radio signal received by the antenna 25 to obtain radio data. The A / D unit 27 converts the wireless data of the analog signal into the wireless data of the digital signal. The frame generation unit 28 stores the radio data of the digital signal in the payload of the uplink RoF frame, stores a control signal including information on the storage position of the payload in the header, and outputs the control signal. The E / O unit 29 converts the upstream RoF frame into an optical signal and transmits it to the base station 1 via the optical fiber 3a.

Similarly, in the repeater 2b, the RF reception front end 26 performs processing such as demodulation and decoding on the radio signal received by the antenna 25 to obtain radio data. The A / D unit 27 converts the wireless data of the analog signal into the wireless data of the digital signal. The frame generation unit 28 stores the radio data of the digital signal in the payload of the uplink RoF frame, stores a control signal including information on the storage position of the payload in the header, and outputs the control signal. The E / O unit 29 converts the upstream RoF frame into an optical signal and transmits it to the base station 1 via the optical fiber 3b.

The transmitting / receiving unit 11a of the base station 1 receives the uplink RoF frame delayed by the uplink one-way delay time ULa from the transmission timing of the repeater 2a. In the transmission / reception unit 11a of the base station 1, the O / E unit 115 converts the optical signal received from the optical fiber 3a into an electrical signal. The frame termination unit 116 detects an uplink RoF frame by detecting a synchronization pattern from the electrical signal, and extracts wireless data based on control information stored in the header. Then, the uplink delay correction unit 117 performs an uplink delay correction process for adding the delay of the uplink delay correction time UTa calculated from Expression (6) to the extracted wireless data (step S5). That is, the uplink delay correction unit 117 delays the radio data by the uplink delay correction time UTa and outputs it to the selection unit 14.

Similarly, the transmission / reception unit 11b of the base station 1 receives the uplink RoF frame delayed by the uplink one-way delay time ULb from the transmission timing of the repeater 2b. In the transmission / reception unit 11b of the base station 1, the O / E unit 115 converts the optical signal received from the optical fiber 3a into an electrical signal. The frame termination unit 116 detects an uplink RoF frame by detecting a synchronization pattern from the electrical signal, and extracts wireless data based on control information stored in the header. Then, the uplink delay correction unit 117 performs an uplink delay correction process for adding the delay of the uplink delay correction time UTb calculated from the equation (7) to the extracted wireless data (step S5). That is, the uplink delay correction unit 117 delays the radio data by the uplink delay correction time UTb and outputs the delayed radio data to the selection unit 14.

In this way, the transmission / reception unit 11a transmits the radio data with a delay of the uplink delay correction time UTa, and the transmission / reception unit 11b transmits the radio data with a delay of the uplink delay correction time UTb. As a result, in the selection unit 14, the timing at which wireless data arrives from the transmission / reception unit 11a is equal to the timing at which wireless data arrives from the transmission / reception unit 11b. Specifically, the selection unit 14 is in a state where delays are aligned from the transmission /

reception units

11a and 11b after the “transmission time of the wireless communication section (4 → 2a) + designated uplink delay time Dup” after the terminal 4 transmits. Wireless data arrives.

For example, when receiving the input of wireless data from the four transmitting / receiving units 11a to 11d, the selecting unit 14 may select one wireless data and output it to the demodulating unit 13. As a method for selecting the wireless data to be output, for example, the selection unit 14 calculates the reception power of the wireless data input from the transmission / reception units 11a to 11d, and selects the wireless data with strong reception power. The selection unit 14 may add four pieces of wireless data input from the transmission / reception units 11a to 11d, or may add using only wireless data whose received power intensity exceeds a prescribed threshold value. Good. Normally, valid radio data from one terminal 4 in a linear communication area is received by at most two repeaters 2. In the base station 1, the delay of the wireless data from the two repeaters 2 can be made uniform by the above-described method, so that the selection unit 14 performs comparison or addition of the reception power of the wireless data with the same signal source. Can do. In any method, in the base station 1, when wireless data is input to the selection unit 14, there is no interference due to multipath via the two repeaters 2 because the delay of the wireless data is uniform. .

Although the method of measuring the round trip delay times RTTa to RTTd before the downlink delay correction process and the uplink delay correction process has been described, the base station 1 is capable of transmitting uplink radio data or downlink radio data even during transmission. The delay measuring units 113 of the transmission / reception units 11a to 11d can always measure the round-trip delay times RTTa to RTTd. Therefore, even when a propagation delay fluctuates due to a temperature change of the optical fibers 3a to 3d, the base station 1 always measures and updates the round trip delay times RTTa to RTTd to absorb the fluctuations and to reduce the delay amount. Can be kept constant.

As in the case of the downlink delay correction process, in practice, the distance between the antenna 25 of the repeaters 2a to 2d and the terminal 4 is not 0 even if it is the shortest. Therefore, when calculating the radio propagation delay time, it is necessary to consider the shortest distance between the terminal 4 and the antenna 25 of the repeater 2. In this case, for example, it is possible to cope with the problem by changing the value of the designated upstream delay time Dup.

FIG. 16 is a flowchart showing the operation of the uplink delay correction process by the uplink delay correction unit 117 of the transmission / reception unit 11 of the base station 1 according to the present embodiment. When the uplink delay correction unit 117 acquires the delay information held by the delay measurement unit 113 (step S91), the uplink delay correction unit 117 calculates the uplink delay correction time using the acquired delay information (step S92), and converts the radio data into the uplink delay correction time. Then, an uplink delay correction process is performed to delay only by (step S93).

Next, the hardware configuration of the base station 1 will be described. As described above, the modulation unit 12 and the demodulation unit 13 are modems, the selection unit 14 is a switch circuit or a synthesis circuit, the E / O unit 114 of the transmission / reception unit 11 is an electro-optical conversion circuit, and the O / E unit 115 is an opto-electric conversion circuit. Can be configured. FIG. 17 is a processing circuit that implements the downlink delay correction unit 111, the frame generation unit 112, the delay measurement unit 113, the frame termination unit 116, and the uplink delay correction unit 117 of the transmission / reception unit 11 of the base station 1 according to the present embodiment. It is a figure which shows the example of a structure of 90. FIG. The processing circuit 90 includes a processor 91 that executes a program stored in the memory 92, a memory 92 that stores information such as a program executed by the processor 91, and an input interface circuit 93 to which data and the like are input from other configurations. An output interface circuit 94 for outputting data and the like to other components is provided, and a processor 91, a memory 92, an input interface circuit 93, and an output interface circuit 94 are connected by a system bus 95.

The processing circuit 90 may be dedicated hardware. When the processing circuit 90 is dedicated hardware, the processing circuit 90 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate). Array) or a combination thereof. The functions of the respective units may be realized by the processing circuit 90, or the functions of the respective units may be collectively realized by the processing circuit 90.

The functions of the downlink delay correction unit 111, the frame generation unit 112, the delay measurement unit 113, the frame termination unit 116, and the uplink delay correction unit 117 of the transmission / reception unit 11 of the base station 1 are realized by the processing circuit 90. That is, the base station 1 acquires delay information necessary for calculating the downlink delay correction time and the uplink delay correction time, calculates the downlink delay correction time and the uplink delay correction time, and performs the downlink delay correction process and the uplink delay correction. A processing circuit 90 for performing processing is provided. In the processing circuit 90, a program stored in the memory 92 is executed by a CPU (Central Processing Unit), a central processing unit, a processing unit, a processing unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), and the like. May be.

The functions of the downlink delay correction unit 111, the frame generation unit 112, the delay measurement unit 113, the frame termination unit 116, and the uplink delay correction unit 117 of the transmission / reception unit 11 of the base station 1 are software, firmware, or a combination of software and firmware. It is realized by. Software or firmware is described as a program and stored in the memory 92. In the processing circuit 90, the processor 91 reads out and executes the program stored in the memory 92, so that the downlink delay correction unit 111, the frame generation unit 112, the delay measurement unit 113, the frame termination unit of the transmission / reception unit 11 of the base station 1 are executed. 116 and the function of the uplink delay correction unit 117 are realized. That is, when executed by the processing circuit 90, the base station 1 obtains the delay information necessary for calculating the downlink delay correction time and the uplink delay correction time, the downlink delay correction time, and the uplink delay correction time. A memory 92 is provided for storing a program in which the step of calculating, the step of performing the downlink delay correction process, and the step of performing the uplink delay correction process are executed as a result. In addition, these programs execute the procedure or method of the downlink delay correction unit 111, the frame generation unit 112, the delay measurement unit 113, the frame termination unit 116, and the uplink delay correction unit 117 of the transmission / reception unit 11 of the base station 1 on a computer. It can be said that Here, the memory 92 is, for example, a RAM, a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), or a nonvolatile or volatile semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact This includes discs, minidiscs, and DVDs (Digital Versatile Discs).

Note that some of the functions of the downlink delay correction unit 111, the frame generation unit 112, the delay measurement unit 113, the frame termination unit 116, and the uplink delay correction unit 117 are realized by dedicated hardware, and part of the functions are software or It may be realized by firmware. For example, the functions of the frame generation unit 112 and the frame termination unit 116 are realized by a processing circuit 90 as dedicated hardware, and the processing circuit 90 is provided for the downlink delay correction unit 111, the delay measurement unit 113, and the uplink delay correction unit 117. The function can be realized by reading and executing the program stored in the memory.

As described above, the processing circuit 90 can realize the above-described functions by hardware, software, firmware, or a combination thereof.

Although the configurations of the downlink delay correction unit 111, the frame generation unit 112, the delay measurement unit 113, the frame termination unit 116, and the uplink delay correction unit 117 of the transmission / reception unit 11 of the base station 1 have been described, the frame generation of the repeaters 2a to 2d The unit 22 and the frame end unit 28 are also realized by the processing circuit 90 shown in FIG.

As described above, according to the present embodiment, in base station 1, delay correction section 113 of each transmission / reception section 11 is necessary for calculating downlink delay correction times DTa to DTd and uplink delay correction times UTa to UTd. The delay information is acquired, the downlink delay correction unit 111 calculates the downlink delay correction times DTa to DTd using the delay information acquired by the delay correction unit 113, performs the downlink delay correction processing, and the uplink delay correction unit 117 Thus, the uplink delay correction processing is performed by calculating the uplink delay correction times UTa to UTd using the delay information acquired by the delay correction unit 113. Thereby, in the base station 1, for the downlink radio data transmitted from the base station 1 to the terminal 4, when the plurality of relays 2 transmit wireless signals as wireless data to the terminal 4, The timing at which the transmitted radio signal arrives at the terminal 4 can be made uniform. Also, with respect to the uplink radio signal transmitted from the terminal 4 to the base station 1, a plurality of repeaters 2 are radio signals that are radio signals from the terminal 4. When data is received, the timing at which the radio data transmitted from each repeater 2 arrives at the selection unit 14 of the base station 1 can be made uniform. As described above, in the mobile communication system 7, when the base station 1 is connected to the repeaters 2a to 2d via the optical fibers 3a to 3d, the lengths of the optical fibers 3a to 3d are not aligned with high accuracy. The propagation delay can be made uniform in communication with the terminal 4 via the repeaters 2a to 2d. In addition, since the base station 1 performs delay correction in consideration of the propagation time of the wireless communication section between the terminal 4 and each repeater 2, the influence of interference waves can be avoided.

The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 base station, 2a, 2b, 2c, 2d repeater, 3a, 3b, 3c, 3d optical fiber, 4 terminal, 5a, 5b, 5c, 5d communication area, 6ab, 6bc, 6cd interference area, 7

mobile communication system

11a, 11b, 11c, 11d, transceiver unit, 12 modulation unit, 13 demodulation unit, 14 selection unit, 21, 115 O / E unit, 22, 116 frame termination unit, 23 D / A unit, 24 RF transmission front end, 25 antenna, 26 RF reception front end, 27 A / D section, 28, 112 frame generation section, 29, 114 E / O section, 111 downlink delay correction section, 113 delay measurement section, 117 upstream delay correction section.

Claims

A base station that is arranged along a moving path of a terminal and is connected to a plurality of relay devices that perform wireless communication with the terminal, and that communicates with the terminal via the relay device,
Each transmitter / receiver includes the same number of transmitters / receivers that communicate with each other by connecting to the relay device,
A frame generation unit for generating a downlink transmission frame to be transmitted to the repeater;
A frame termination unit for detecting an upstream transmission frame transmitted from the relay unit;
Measures the delay generated in communication between the own transmitting / receiving unit and the repeater connected to the own transmitting / receiving unit to obtain delay information, and also occurs in communication between the repeater connected to the own transmitting / receiving unit and the terminal. A delay measuring unit that acquires information on a delay to be performed and information on a delay time allowed in communication between the base station and the terminal, and holds the acquired information;
A downlink delay correction unit that calculates downlink delay correction time using information held by the delay measurement unit, and delays radio data stored in the downlink transmission frame using the downlink delay correction time;
An uplink delay correction unit that calculates an uplink delay correction time using the information held by the delay measurement unit, and delays the radio data stored in the uplink transmission frame using the uplink delay correction time;
A base station comprising:
The delay measurement unit measures a round trip delay time between the own transmission / reception unit and a repeater connected to the own transmission / reception unit, calculates a downlink one-way delay time using the round trip delay time, and The radio propagation delay time of a radio signal that is a signal in the radio communication section of the radio data from the repeater to which the own transmitting / receiving unit is connected to the terminal, and the radio propagation delay time of the radio signal from the reference repeater to the terminal A radio propagation delay time difference that is a difference between the base station and the terminal to obtain information on a specified downlink delay time allowed in downlink communication from the base station to the terminal,
The downlink delay correction unit calculates a downlink delay correction time using the specified downlink delay time, the radio propagation delay time difference, and the downlink one-way delay time,
The base station according to claim 1.
The delay measurement unit calculates a round-trip delay time between the own transmission / reception unit and a repeater connected to the own transmission / reception unit, calculates an upstream one-way delay time using the round-trip delay time, and The radio propagation delay time of a radio signal that is a signal in the radio communication section of the radio data from the repeater to which the own transmitting / receiving unit is connected to the terminal, and the radio propagation delay time of the radio signal from the reference repeater to the terminal A radio propagation delay time difference that is a difference between the terminal and the terminal to obtain information on a designated uplink delay time allowed in uplink communication from the terminal to the base station,
The uplink delay correction unit calculates an uplink delay correction time using the specified uplink delay time, the radio propagation delay time difference, and the uplink one-way delay time,
The base station according to claim 1.
The frame generation unit notifies the delay measurement unit of the start timing of the synchronization pattern of the downlink transmission frame;
The frame termination unit notifies the delay measurement unit of the timing at which the synchronization pattern of the uplink transmission frame is detected,
The delay measurement unit calculates a round-trip delay time between the own transmission / reception unit and a repeater connected to the own transmission / reception unit, using timing information notified from the frame generation unit and the frame termination unit.
The base station according to claim 2 or 3, wherein
When the plurality of repeaters communicate with the terminal using antennas each having directivity,
The delay measuring unit uses radio relay delay time of a radio signal from the repeater connected to the own transmission / reception unit to the terminal using position information of the repeater connected to the own transmission / reception unit and a reference relay. Calculating a radio propagation delay time difference that is a difference from a radio propagation delay time of a radio signal from the reference repeater to the terminal;
The base station according to claim 2, 3, or 4.
A repeater connected to the base station according to any one of claims 1 to 5,
A frame termination unit for notifying a timing at which a synchronization pattern of a downlink transmission frame transmitted from the base station is detected;
A frame generation unit that generates an uplink transmission frame at a timing notified from the frame termination unit;
A relay device comprising:
A base station according to any one of claims 1 to 5,
A plurality of repeaters according to claim 6;
A mobile communication system comprising:
A delay correction method for a base station that is arranged along a movement path of a terminal and is connected to a plurality of relay devices that perform wireless communication with the terminal, and communicates with the terminal via the relay device,
An acquisition step of acquiring information necessary for calculating a downlink delay correction time to a radio signal transmitted to the relay device and an uplink delay correction time to a radio signal received from the relay device;
A calculation step of calculating the downlink delay correction time and the uplink delay correction time using the information acquired in the acquisition step;
A delay correction step for performing a downlink delay correction process and an uplink delay correction process for delaying radio data using the downlink delay correction time and the uplink delay correction time calculated in the calculation step;
A delay correction method comprising: