Optical repeater device and relay method

Abstract

To provide an optical repeater device and a relay method with which it is possible to achieve synchronization at the RF output point of a slave unit between a plurality of optical repeater systems.SOLUTION: An optical repeater device of an embodiment comprises a timing detection unit, a timing acquisition unit, and a synchronization unit. The timing detection unit detects downlink and uplink switching timings for each of a plurality of base station devices. The timing acquisition unit acquires information regarding the downlink and uplink switching timings, for a plurality of base station devices connected to other optical repeater devices. The synchronization unit synchronizes signals from the plurality of base station devices connected to the optical repeater device, on the basis of the switching timings detected by the timing detection unit and the information acquired by the timing acquisition unit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0005]

[0001] Embodiments of this invention relate to an optical repeater device and a relay method for expanding the communication area of a mobile communication network.

Background Art

[0002] Recently, in order to eliminate the dead zones of mobile communication terminals such as mobile phones and smartphones, the introduction of optical repeater systems (DAS (Distributed Antenna System)) has been progressing. In an optical repeater system, a master unit (MU), that is, an optical repeater device, connected to a radio base station of a mobile communication network and slave units (RUs) that transmit and receive radio signals to and from a mobile communication terminal are connected by an optical line, and a plurality of these slave units are distributedly arranged to expand the communication area. In particular, it is useful for covering a wide indoor area such as a large commercial facility or an office building.

[0003] Generally, as communication methods between a radio base station and a mobile communication terminal, there are two types: the FDD (Frequency Division Duplex) method that uses different frequencies for each of the uplink (hereinafter, UL (Up Link)) and downlink (hereinafter, DL (Down Link)) communications, and the TDD (Time Division Duplex) method that uses one frequency in a time division manner.

[0004] In recent years, carrier aggregation (hereinafter, CA (Career Aggregation)), a technology that realizes an improvement in communication speed by simultaneously using a plurality of frequency bands in a time division manner, has been put into practical use. When CA is realized in a frequency band of a TDD system such as 5G (the fifth-generation mobile communication system), the switching timing difference of UL / DL between frequency bands is within 3 μs as defined by 3GPP (registered trademark).

[0005] However, the above regulations apply to the RF output point of a wireless base station and do not take into account the case where an optical repeater system is introduced at the wireless base station. As a result, at the RF output points of multiple slave units in the optical repeater system, the UL / DL switching timing difference between frequency bands may not fall within the 3GPP (registered trademark) regulations, potentially preventing the CA effect from being achieved.

[0006] Furthermore, in recent times, multiple optical repeater systems (or multiple master units) are sometimes introduced to cover a common communication area. In this case, even if the RF output points can be synchronized between slave units in each optical repeater system, there is a problem in that synchronization is not maintained between the optical repeater systems (master units). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 6602813 [Patent Document 2] Patent No. 6567438 [Non-patent literature]

[0008] [Non-Patent Document 1] Optical repeater device for addressing dead zones for mobile devices in 5G communication, Toshiba Review Vol. 76 No. 2 [Overview of the project] [Problems that the invention aims to solve]

[0009] The problem that this invention aims to solve is to provide an optical repeater device and relay method that can synchronize the RF output points of slave units among multiple optical repeater systems. [Means for solving the problem]

[0010] The optical repeater device of this embodiment comprises a timing detection unit, a timing acquisition unit, and a synchronization unit. The timing detection unit detects the downlink and uplink switching timings for multiple base station devices, respectively. The timing acquisition unit acquires information regarding the downlink and uplink switching timings for multiple base station devices connected to other optical repeater devices. The synchronization unit synchronizes the signals from the multiple base station devices connected to the optical repeater device based on the switching timings detected by the timing detection unit and the information acquired by the timing acquisition unit. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram showing an example configuration of an optical repeater system equipped with an optical repeater device according to this invention. [Figure 2] A functional block diagram showing the specific configuration of the optical repeater system shown in Figure 1. [Figure 3] A flowchart illustrating the processing of the TDD timing comparison unit shown in Figure 2. [Figure 4] A flowchart illustrating the processing of the monitoring and control unit shown in Figure 2. [Figure 5] A functional block diagram showing another example of the signal processing units 110-1 to 110-3 shown in Figure 2. [Modes for carrying out the invention]

[0012] An embodiment will be described below with reference to the drawings. Figure 1 shows the configuration of an optical repeater system equipped with an optical repeater device according to the embodiment, and the concept of a method for correcting the UL / DL switching timing difference using this system.

[0013] This optical repeater system consists of master units 100a and 100b, which correspond to optical repeater devices (MU: Master Unit), slave units 200a-1 to 200a-3 and 200b-1 to 200b-3, which correspond to RU (Remote Unit), and a repeater unit 300 (HUB).

[0014] In this example, for the sake of simplicity, two master units (100a, 100b) are used as described above, and three slave units (200a-1 to 200a-3, 200b-1 to 200b-3) are respectively accommodated in each of them. However, it is not limited to this.

[0015] The master unit 100a is connected by coaxial cables to TDD radios BS-A, BS-B, and BS-C, which are base station devices connected to the mobile communication network of the communication carrier. Similarly, the master unit 100b is connected by coaxial cables to TDD radios BS-a, BS-b, and BS-c, which are base station devices of the communication carrier. The master unit 100a and the master unit 100b are connected to each other by, for example, a twisted pair cable.

[0016] In this connection by coaxial cable, for each base station (TDD radio), for example, four radio signals are transmitted at 100 MHz band × 4 (4×4 MIMO).

[0017] Also, in the following description, it is assumed that the TDD radios BS-A, BS-B, and BS-C transmit and receive radio signals in different frequency bands fA, fB, and fC from each other, and similarly, the TDD radios BS-a, BS-b, and BS-c transmit and receive radio signals in different frequency bands fa, fb, and fc from each other.

[0018] In this example, for the sake of simplicity, the case where each master unit 100a, 100b accommodates three TDD radios (BS-A, BS-B, BS-C and BS-a, BS-b, BS-c) is taken as an example for explanation, but it is not limited to three.

[0019] Note that even if the TDD radios BS-A, BS-B, and BS-C are base station devices of the same communication carrier, the UL / DL switching timing difference can occur within a range of within 3 μs. Similarly, even if the TDD radios BS-a, BS-b, and BS-c are base station devices of the same communication carrier, the UL / DL switching timing difference can occur within a range of within 3 μs.

[0020] The UL / DL switching timing difference between the TDD radios BS-A, BS-B, and BS-C in the master device 100a can be adjusted by the master device 100a. Similarly, the UL / DL switching timing difference between the TDD radios BS-a, BS-b, and BS-c in the master device 100b can be adjusted by the master device 100b.

[0021] However, a delay difference may occur between the master device 100a and the master device 100b after adjusting the switching timing difference. The causes of this include the accuracy of GMC, the misalignment of eNB / gNB, and the difference in coaxial cable length between the master device 100a and the master device 100b. In contrast, in this embodiment, the master device 100a and the master device 100b exchange information with each other, and each master device performs a first correction process according to the same logic based on substantially the same information to correct the delay difference related to the connected TDD radio. The specific method of the first correction process will be described in detail later.

[0022] On the other hand, the master device 100a houses the slave devices 200a-1 to 200a-3. The master device 100a and each of the slave devices 200a-1 to 200a-3 are connected by optical fibers respectively, and for example, digital transmission is performed at 25 Gbit / s.

[0023] Similarly, the master device 100b houses the slave devices 200b-1 to 200b-3. The master device 100b and the slave device 200b-1 are directly connected by an optical fiber, and the master device 100b and the slave devices 200b-2 and 200b-3 are connected by optical fibers via the relay device 300 respectively. Similarly, digital transmission is performed at 25 Gbit / s on the optical fibers.

[0024] [[ID=第十九]]Even if the UL / DL switching timing is synchronized at the output ends of the master device 100a to the slave devices 200a-1 to 200a-3, a UL / DL switching timing difference may occur between the slave devices 200a-1 to 200a-3. The same is true for the slave devices 200b-1 to 200b-3. This is due to the transmission delay caused by the difference in the optical fiber length between the master device and the slave devices and the processing delay difference in each device.

[0025] The difference in UL / DL switching timing between the master unit 100a and each slave unit 200a-1 to 200a-3 can be adjusted by the master unit 100a, and similarly, the difference in UL / DL switching timing between the master unit 100b and each slave unit 200b-1 to 200b-3 can be adjusted by the master unit 100b.

[0026] In the master unit 100a, the difference in UL / DL switching timing caused by the transmission delay difference between slave units 200a-1 to 200a-3 can be adjusted by the master unit 100a. Similarly, in the master unit 100b, the difference in UL / DL switching timing caused by the transmission delay difference between slave units 200b-1 to 200b-3 can be adjusted.

[0027] However, a delay in adjustments to the slave unit may occur between the master unit 100a and the master unit 100b. This is also caused by transmission delays resulting from differences in optical fiber length and processing delays in each device.

[0028] In contrast, in this embodiment, the master unit 100a and master unit 100b exchange information with each other, and each master unit performs a second correction process based on substantially the same information and logic to correct the delay difference of the slave units under their respective control. The specific method of the second correction process will be described in detail later.

[0029] Figure 2 is a functional block diagram illustrating the configuration of the master unit 100a, master unit 100b, and slave units 200a-1 to 200a-3 and 200b-1 to 200b-3. Note that for master unit 100b, the diagram and some explanations are omitted as it is the same as master unit 100a. Similarly, for slave units 200a-2 to 200a-3 and 200b-1 to 200b-3, the diagram and some explanations are omitted as they are the same as slave unit 200a-1.

[0030] The master unit 100a comprises signal processing units 110-1 to 110-3, a TDD timing comparison unit 120, a multiplexing / separation unit 130, and a monitoring / control unit 140. The TDD timing comparison unit 120 and the monitoring / control unit 140 can be configured using a processor and memory. That is, they can be realized by the processor operating based on the control program and control data stored in memory.

[0031] The signal processing units 110-1 to 110-3 are connected to their respective TDD radio transceivers BS-A, BS-B, and BS-C by coaxial cables, and transmit and receive radio signals to and from the mobile communication terminal UE via the aforementioned coaxial cables.

[0032] Specifically, the signal processing units 110-1 to 110-3 each include a transmit / receive selector switch (SW) 111, a detector 112, an A / D converter (ADC) 113, a TDD timing synchronization unit 114, a TDD timing delay adjustment unit 115, a D / A converter (DAC) 116, and a transmission delay detection unit 117, respectively.

[0033] Since signal processing units 110-1 to 110-3 have similar configurations, the following explanation will focus on signal processing unit 110-1. However, it will be easy for those skilled in the art to interpret the explanations of signal processing units 110-2 and 110-3 as appropriate.

[0034] The transmit / receive selector switch 111 switches the transmission and reception timing with the TDD radio BS-A at a timing synchronized with the timing signal provided by the TDD timing synchronization unit 114, which will be described later, thereby realizing TDD communication.

[0035] The detector 112 detects the RF signal received from the TDD radio BS-A and detects the switching timing between uplink and downlink. That is, when detection is performed by the detector 112, the TDD timing synchronization unit 114 outputs a timing signal so that the transmit / receive selector switch 111 temporarily continues to receive the downlink. Note that the detector 112 and the TDD timing synchronization unit 114 are examples of timing detection units.

[0036] The A / D converter 113 down-converts the RF signal received from the TDD radio BS-A into a baseband signal, then performs A / D conversion and outputs it to the TDD timing delay adjustment unit 115.

[0037] The TDD timing synchronization unit 114 generates a timing signal (pulse signal) synchronized with the switching timing detected by the detector 112, and outputs this timing signal to the transmit / receive selector switch 111 and the TDD timing comparison unit 120.

[0038] The TDD timing comparison unit 120 performs internal delay difference detection processing, master-machine timing difference detection processing, and total delay difference detection processing. The TDD timing comparison unit 120 is an example of a timing acquisition unit, a synchronization unit (internal delay detection unit, external delay detection unit), and a timing information transmission unit.

[0039] The processing of the TDD timing comparison unit 120 will be explained below with reference to Figure 3. In the internal delay difference detection process, the TDD timing comparison unit 120 acquires timing signals from signal processing units 110-1 to 110-3 as step S301. That is, the TDD timing comparison unit 120 acquires the detected timing signals for TDD radios BS-A, BS-B, and BS-C, respectively.

[0040] Then, in step S302, the TDD timing comparison unit 120 compares the three timing signals to detect internal delay amounts DA, DB, and DC to correct the delay difference between the TDD radios BS-A, BS-B, and BS-C.

[0041] In other words, the internal delay amounts DA, DB, and DC correspond to the amount of adjustment for the transmission and reception timing in the signal processing units 110-1 to 110-3, which synchronize the switching timing of signals from each TDD radio BS-A, BS-B, and BS-C to a predetermined reference timing.

[0042] To explain this detection in more detail, for example, in order to synchronize the timing with the TDD radio with the slowest switching timing, the slowest switching timing (or a predetermined timing based on it) is defined as the internal target timing T100A, and the difference between this internal target timing T100A and the timing signals detected by each signal processing unit 110-1 to 110-3 is detected as the internal delay amounts DA, DB, and DC.

[0043] Next, in the master unit timing difference detection process, the TDD timing comparison unit 120 notifies (transmits) the internal target timing T100A to the other master unit 100b as step S303, and as step S304, detects (receives) the notification of the internal target timing T100B similarly determined by the other master unit 100b.

[0044] Then, as step S305, the TDD timing comparison unit 120 detects the master-machine timing difference D100 between the internal target timing T100A and the internal target timing T100B.

[0045] To explain this detection in more detail, for example, in order to match the latest internal target timing of the master unit, that latest internal target timing (or a predetermined timing based on it) is defined as the common target timing S100, and the difference between this common target timing S100 and the unit's own internal target timing T100A is detected as the master unit timing difference D100.

[0046] Next, in the total delay difference detection process, the TDD timing comparison unit 120, in step S306, determines the delay adjustment amounts DA100, DB100, and DC100 to be used for delay adjustment in each signal processing unit 110-1 to 110-3 based on the internal delay amounts DA, DB, and DC obtained in the internal delay difference detection process and the inter-master timing difference D100 obtained in the inter-master timing difference detection process, and outputs them to the corresponding signal processing units 110-1 to 110-3.

[0047] In other words, the delay adjustment amounts DA100, DB100, and DC100 are information that corrects both the delay difference between the TDD radios BS-A, BS-B, and BS-C within the master unit 100a, and the delay difference between master unit 100a and master unit 100b.

[0048] The TDD timing delay adjustment unit 115 applies a delay to the output of the A / D converter (ADC) 113 according to the delay adjustment amount DA100 output from the TDD timing comparison unit 120, thereby delaying the switching timing. This realizes the first correction process shown in Figure 1. Note that the TDD timing delay adjustment unit 115 is an example of a synchronization unit (delay adjustment unit).

[0049] The multiplexing unit 130 converts the signals output from the TDD timing delay adjustment unit 115 of each signal processing unit 110-1 to 110-3 into optical signals, multiplexes them, and transmits them to the slave units 200a-1 to 200a-3 via optical fiber.

[0050] The multiplexing unit 130 also receives optical signals from each slave unit 200a-1 to 200a-3 via optical fiber, performs photoelectric conversion, and extracts digital signals. These digital signals are converted to analog signals by a D / A converter (DAC) 116, then upconverted to radio frequencies, and transmitted to the TDD radio BS-A via a transmit / receive switch 111 and coaxial cable.

[0051] The transmission delay detection unit 117 detects the amount of transmission delay between the master unit 100a and the slave unit 200a-1 by exchanging control signals with the slave unit 200a-1. The transmission delay detection unit 117 of the signal processing unit 110-2 and the transmission delay detection unit 117 of the signal processing unit 110-3 similarly detect the amount of transmission delay between the master unit 100a and the slave unit 200a-2 or between the master unit 100a and the slave unit 200a-3. These transmission delay amounts are output to the monitoring control unit 140. Note that the transmission delay detection unit 117 is an example of a delay amount detection unit.

[0052] The monitoring and control unit 140 performs internal transmission difference detection processing, master-unit transmission difference detection processing, and total transmission difference detection processing. The monitoring and control unit 140 is an example of a delay amount acquisition unit, a synchronization control unit (internal delay detection unit, external delay detection unit, delay information generation unit), and a delay information transmission unit.

[0053] The processing of the monitoring and control unit 140 will be explained below with reference to Figure 4. In the internal transmission difference detection process, the monitoring control unit 140 obtains the transmission delay amount from the signal processing units 110-1 to 110-3 as step S401. That is, the monitoring control unit 140 obtains the detected transmission delay amount for each of the slave units 200a-1 to 200a-3.

[0054] Then, in step S402, the monitoring control unit 140 compares three transmission delay amounts and detects internal delay amounts D1, D2, and D3 to correct the transmission delay difference between slave units 200a-1 to 200a-3.

[0055] In other words, the internal delay amounts D1, D2, and D3 correspond to the adjustment amounts for the transmission delay in each slave unit 200a-1 to 200a-3 in order to match the delay amount of each slave unit 200a-1 to 200a-3 to a predetermined reference delay amount.

[0056] To explain this detection in more detail, for example, the largest delay amount (or a predetermined delay amount based on it) is set as the internal target delay amount T200A to match the largest delay amount (in the example in Figure 1, slave unit 200a-3), and the difference between this internal target delay amount T200A and the transmission delay amounts of each slave unit 200a-1 to 200a-3 is detected as the internal delay amounts D1, D2, and D3.

[0057] Next, in the master unit transmission difference detection process, the monitoring control unit 140, in step S403, notifies (transmits) the internal target delay amount T200A to the other master unit 100b, and in step S404, detects (receives) the notification of the internal target delay amount T200B similarly determined by the other master unit 100b.

[0058] Then, in step S405, the monitoring control unit 140 detects the inter-master delay difference D200 between the internal target delay amount T200A and the internal target delay amount T200B.

[0059] To explain this detection in more detail, for example, the largest internal target delay amount (or a predetermined delay amount based on it) of the master unit (in the example in Figure 1, master unit 100a; slave units 200a-3 have the largest delay) is set as the common target delay amount S200, and the difference between this common target delay amount S200 and the unit's own internal target delay amount T200A is detected as the master-unit delay difference D200.

[0060] Next, in the total transmission difference detection process, the monitoring control unit 140, in step S406, calculates the delay adjustment amounts D1200, D2200, and D3200 to be used for adjusting the transmission delay in each slave unit 200a-1 to 200a-3, based on the internal delay amounts D1, D2, and D3 obtained in the internal transmission difference detection process and the master unit delay difference D200 obtained in the master unit transmission difference detection process, and outputs them to the corresponding slave units 200a-1 to 200a-3.

[0061] In other words, the delay adjustment amounts D1200, D2200, and D3200 are information that corrects both the difference in transmission delay between the master unit 100a and the slave units 200a-1 to 200a-3, and the difference in transmission delay between the master unit 100a and the master unit 100b.

[0062] The monitoring control unit 140 transmits the delay adjustment amount D1200 to the slave unit 200a-1 via the multiplexing / separation unit 130. Similarly, the monitoring control unit 140 transmits the delay adjustment amounts D2200 and D3200 to the corresponding slave units 200a-2 and 200a-3 via the multiplexing / separation unit 130.

[0063] The sub-unit 200a-1 includes a multiplexing / separation unit 210, a monitoring / control unit 220, a delay adjustment unit 230, a digital-to-analog converter (DAC) 240, a transmit / receive selector switch (SW) 250, and an analog-to-digital converter (ADC) 260.

[0064] Since the sub-units 200a-1 to 200a-3 have similar configurations, the following explanation will focus on sub-unit 200a-1. However, it should be easy for those skilled in the art to interpret the explanations of sub-units 200a-2 and 200a-3 as appropriate.

[0065] The multiplexing / decoupling unit 210 separates the multiplexed optical signals, converts the optical signals into electrical signals, and extracts the digital downlink signal.

[0066] The monitoring control unit 220 detects the signal destined for the slave unit 200a-1 from the downlink signal, and also detects the delay adjustment amount D1200 sent from the monitoring control unit 140 of the master unit 100a included in this signal, and outputs it to the delay adjustment unit 230.

[0067] The delay adjustment unit 230 delays the transmission timing of the downlink signal based on the delay adjustment amount D1200 output from the monitoring control unit 220 and outputs it to the D / A converter 240. 1 The second correction process shown is then implemented.

[0068] The D / A converter 240 converts the downlink signal into an analog signal, which is then used to modulate the carrier wave. The modulated carrier wave is upconverted to a radio frequency and then radiated into space through the transmit / receive switch 250 and the antenna.

[0069] The mobile communication terminal UE communicates by switching between transmitting and receiving (uplink / downlink) at a timing based on the radio signal (downlink) received from the slave unit 200a-1. As a result, the RF signal transmitted from the mobile communication terminal UE is output to the A / D converter 260 via the antenna and transmit / receive switch 250.

[0070] The A / D converter 260 down-converts the RF signal received from the mobile communication terminal UE into a baseband signal, then performs A / D conversion and outputs it to the multiplexing / decompression unit 210.

[0071] The multiplexing and decoupling unit 210 converts the digital signal output from the A / D converter 260 into an optical signal, multiplexes it, and transmits it to the master unit 100a via an optical fiber.

[0072] As described above, in the optical repeater system with the above configuration, the master unit 100a determines the internal target timing T100A through internal delay difference detection processing, detects the delay amount (internal delay amounts DA, DB, DC) for each TDD radio BS-A, BS-B, and BS-C, then detects the inter-master unit timing difference D100 between the internal target timing T100A and the internal target timing T100B of the other master unit 100b through inter-master unit timing difference detection processing, and adjusts the UL / DL switching timing to synchronize with all TDD radios (BS-A, BS-B, BS-C and BS-a, BS-b, BS-c) through total delay difference detection processing.

[0073] Therefore, with the master unit 100a of the optical repeater system configured above, the UL / DL switching timing difference between TDD radios BS-A, BS-B, BS-C and TDD radios BS-a, BS-b, BS-c is corrected, so that the UL / DL switching timing can be synchronized not only at the output terminals to the subordinate slave units 200a-1 to 200a-3 under the master unit 100b, but also at the output terminals to the subordinate slave units 200b-1 to 200b-3 under the master unit 100b.

[0074] It will be easily understood by those skilled in the art that the synchronization process for the UL / DL switching timing in the master unit 100a (master unit 100b) described above is equivalent to detecting the difference in UL / DL switching timing between TDD radios BS-A, BS-B, BS-C and TDD radios BS-a, BS-b, BS-c, and adjusting the UL / DL switching timing to synchronize with all TDD radios.

[0075] Furthermore, in the optical repeater system with the above configuration, the master unit 100a determines an internal target delay amount T200A through internal transmission difference detection processing, detects the transmission delay amount (internal delay amounts D1, D2, D3) for each slave unit 200a-1 to 200a-3, then detects the inter-master unit delay difference D200 between the internal target delay amount T200A and the internal target delay amount T200B of the other master unit 100b through inter-master unit transmission difference detection processing, and adjusts the UL / DL switching timing to synchronize with all slave units (200a-1 to 200a-3 and 200b-1 to 200b-3) through total transmission difference detection processing.

[0076] Therefore, with the master unit 100a of the optical repeater system configured above, the difference in UL / DL switching timing between slave units 200a-1 to 200a-3 and slave units 200b-1 to 200b-3 is corrected, so that the UL / DL switching timing can be synchronized not only at the output terminals from the subordinate slave units 200a-1 to 200a-3 to the mobile communication terminal UE, but also at the output terminals from the slave units 200b-1 to 200b-3 under the master unit 100b to the mobile communication terminal UE.

[0077] It will be easily understood by those skilled in the art that the synchronization process for the UL / DL switching timing in the master unit 100a (master unit 100b) described above is equivalent to detecting the transmission delay amount for slave units 200a-1 to 200a-3 and slave units 200b-1 to 200b-3 and adjusting the UL / DL switching timing to synchronize with all slave units.

[0078] It should be noted that this invention is not limited to the embodiments described above, and in the implementation stage, the components can be modified and implemented without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the embodiments. For example, a configuration in which some components are removed from all the components shown in the embodiments is also conceivable. Moreover, components described in different embodiments may be appropriately combined.

[0079] For example, although the above embodiment described the case where there are two master units 100a and master unit 100b, it will be easily understood by those skilled in the art that synchronization can be achieved in the same manner even when there are three or more master units.

[0080] Furthermore, the first correction process shown in Figure 1, and Figure 1 The second correction process described above involves delay processing, which may cause the timing of the RF signals transmitted downlink from slave units 200a-1 to 200a-3 to deviate from the timing specified by 3GPP®. Therefore, it is possible to advance the TDD timing on the TDD radio BS-A to BS-C side in anticipation of the delays caused by the first and second correction processes. In this way, it becomes possible to align the radio frequency (RF) output points of slave units 200a-1 to 200a-3 with the TDD timing specified by 3GPP®.

[0081] Furthermore, Figure 2 shows a configuration in the signal processing unit 110-1 where the RF signal received from the TDD radio BS-A is detected by the detector 112 to detect the uplink and downlink switching timing. Alternatively, the configuration shown in Figure 5 may be used. Figure 5 is a functional block diagram showing another example of the signal processing units 110-1 to 110-3. The signal processing unit 110-1 shown in Figure 5 includes a timing detection unit 118 connected downstream of the A / D converter 113. The timing detection unit 118 detects the uplink and downlink switching timing from the digital signal obtained by digitally converting the RF signal. In other words, the timing detection unit 118 extracts the TDD timing by demodulating the digital signal and interpreting the data contained in the digital signal. Thus, the TDD timing may be detected in the digital domain.

[0082] It goes without saying that the invention can also be implemented in a similar manner by making various modifications without departing from the spirit of the invention. [Explanation of Symbols]

[0083] 100a...Master unit, 100b...Master unit, 110-1~110-3...Signal processing unit, 111...Transmit / receive selector switch, 112...Detector, 113...A / D converter, 114...TDD timing synchronization unit, 115...TDD timing delay adjustment unit, 116...D / A converter, 117...Transmission delay detection unit, 118...Timing detection unit, 120...TDD timing comparison unit, 130... Multiplexing unit, 140...monitoring control unit, 200a-1~200a-3...slave unit, 200b-1~200b-3...slave unit, 210...multiplexing unit, 220...monitoring control unit, 230...delay adjustment unit, 240...D / A converter, 250...transmit / receive switch, 260...A / D converter, 300...repeater, BS-A~BS-C...TDD radio, BS-a~BS-c...TDD radio.

Claims

1. An optical repeater device that connects multiple base station devices connected to a mobile communication network and transmitting and receiving radio signals in different frequency bands to multiple slave devices communicating wirelessly with a mobile communication terminal using a time-division multiplexing method, Each of the aforementioned multiple base station devices includes a timing detection unit that detects the switching timing between the downlink and uplink, A timing acquisition unit that acquires information regarding the downlink and uplink switching timing for multiple base station devices connected to other optical repeater devices, A synchronization unit performs a first correction process to synchronize the downlink and uplink switching timing of its own device with the downlink and uplink switching timing of the other optical repeater device, based on the switching timing detected by the timing detection unit and the information acquired by the timing acquisition unit. An optical repeater device equipped with the following features.

2. The aforementioned synchronization unit, An internal delay amount detection unit detects the latest switching timing among the switching timings of the multiple base station devices detected by the timing detection unit, and detects the difference between this latest switching timing and the switching timing of each base station device as an internal delay amount. An external delay detection unit detects the latest switching timing for multiple base station devices connected to other optical repeater devices, based on the information acquired by the timing acquisition unit. A delay adjustment unit delays and synchronizes the signals from the multiple base station devices connected to the device, based on the latest switching timing detected by the internal delay detection unit and the internal delay amount, and the latest switching timing detected by the external delay detection unit. The optical repeater device according to claim 1, comprising:

3. Furthermore, the optical repeater device according to claim 2, further comprising a timing information transmission unit that transmits the latest switching timing detected by the internal delay detection unit as information regarding the switching timing between the downlink and uplink to the other optical repeater device.

4. An optical repeater device that connects multiple base station devices connected to a mobile communication network and transmitting and receiving radio signals in different frequency bands to multiple slave devices communicating wirelessly with a mobile communication terminal using a time-division multiplexing method, A delay amount detection unit that detects the transmission delay amount between each of the aforementioned plurality of slave units, A delay amount acquisition unit that acquires information regarding the transmission delay amount between multiple slave units connected to other optical repeater devices and the other optical repeater devices, A synchronization control unit transmits to each of the multiple slave units information to perform a second correction process that synchronizes the downlink and uplink switching timing of the multiple slave units connected to its own device with the downlink and uplink switching timing of the multiple slave units connected to the other optical repeater device, based on the transmission delay amount detected by the delay amount detection unit and the information acquired by the delay amount acquisition unit. An optical repeater device characterized by comprising the following features.

5. The synchronization control unit, An internal delay detection unit detects the largest transmission delay among the transmission delays between the multiple slave units detected by the delay detection unit, and detects the difference between this largest transmission delay and the transmission delay of each slave unit as the internal delay. An external delay detection unit detects the largest transmission delay amount for multiple slave units connected to other optical repeater devices, based on the information acquired by the aforementioned delay amount acquisition unit. A delay information generation unit generates information based on the largest transmission delay detected by the internal delay detection unit and the internal delay, and the largest transmission delay detected by the external delay detection unit, which generates delay amounts to delay the signals transmitted from the multiple slave units connected to the device to the mobile communication terminal. The optical repeater device according to claim 4, comprising:

6. Furthermore, the optical repeater device according to claim 5, further comprising a delay information transmission unit that transmits the largest transmission delay amount detected by the internal delay amount detection unit to the other optical repeater device as information regarding the transmission delay amount between itself and a plurality of slave devices connected to it.

7. A relay method for an optical repeater device that connects multiple base station devices connected to a mobile communication network and transmitting and receiving radio signals in different frequency bands to multiple slave devices communicating wirelessly with a mobile communication terminal using a time-division multiplexing scheme, For the aforementioned multiple base station devices, a timing detection step is performed to detect the switching timing of the downlink and uplink, respectively. A timing acquisition process to acquire information regarding the downlink and uplink switching timing for multiple base station devices connected to other optical repeater devices, A synchronization step is performed to synchronize the downlink and uplink switching timing of the device itself with the downlink and uplink switching timing of the other optical repeater device, based on the switching timing detected in the timing detection step and the information acquired in the timing acquisition step. A relay method equipped with the following features.

8. A relay method for an optical repeater device that connects multiple base station devices connected to a mobile communication network and transmitting and receiving radio signals in different frequency bands to multiple slave devices communicating wirelessly with a mobile communication terminal using a time-division multiplexing scheme, A delay amount detection step for detecting the transmission delay amount between each of the aforementioned plurality of slave units, A delay amount acquisition step is to acquire information regarding the transmission delay amount between multiple slave units connected to other optical repeater devices and the other optical repeater devices, A synchronization control step that transmits information to each of the multiple slave units for performing a second correction process to synchronize the downlink and uplink switching timing of the multiple slave units connected to the device itself and the downlink and uplink switching timing of the multiple slave units connected to the other optical repeater device, based on the transmission delay amount detected in the delay amount detection step and the information acquired in the delay amount acquisition step. A relay method equipped with the following features.

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