JP6935358B2 - Signal transmission equipment, signal transmission systems and methods - Google Patents

Description

Embodiments of the present invention relate to signal transmission devices, signal transmission systems and methods.

The wireless transmission system used in mobile communication terminal devices such as mobile phones and smartphones is the same frequency band as the FDD (Frequency Division Duplex) system, which uses two different frequency bands as a pair as downlink signal / uplink signal. Is known as a TDD (Time Division Duplex) system, which is shared by a downlink signal and an uplink signal and is used in time division.

JP-A-2007-006163 Japanese Unexamined Patent Publication No. 11-008879 Japanese Unexamined Patent Publication No. 08-237731

By the way, in the FDD wireless transmission system, a certain frequency interval (Gap) is required between the downlink frequency band and the uplink frequency band, and the available frequencies are becoming tight. In recent years, the use of the TDD wireless transmission system has been increasing.

Therefore, it is conceivable that the number of devices using the TDD wireless transmission system will increase in the shared repeater system as well.
In a shared repeater system that employs a TDD wireless transmission system, transmission and reception are performed at different timings, and the transmission speed and transmission delay amount may differ between the uplink and downlink, resulting in time accuracy. It was difficult to secure.

The present invention has been made in view of the above, and signal transmission capable of reliably ensuring time accuracy even in a transmission system that employs a TDD wireless transmission method to provide a service. It is intended to provide equipment, signal transmission systems and methods.

The signal transmission device of the embodiment is a signal transmission device that performs signal transmission by the TDD method, and has a switch unit that separates a time synchronization signal included in the input transmission signal and a signal other than the time synchronization signal. The first transmission line for transmitting signals other than the time synchronization signal, the second transmission line for transmitting the time synchronization signal, the transmission signal from the first transmission line, and the transmission signal from the second transmission line side are combined, and the second transmission line is used. It includes a composite distributor that distributes a transmission signal to one transmission line side and a transmission signal to a second transmission line side.

FIG. 1 is a schematic block diagram of the communication network of the embodiment. FIG. 2 is a schematic block diagram of the coaxial transmission device. FIG. 3 is an explanatory diagram of an example of frequency allocation to PTP packet data and other packet data. FIG. 4 is an explanatory diagram of a time synchronization processing procedure by PTP. FIG. 5 is a schematic block diagram of the repeater device of the second embodiment.

[1] First Embodiment Next, the embodiment will be described in detail with reference to the drawings.
FIG. 1 is a schematic block diagram of the communication network of the embodiment.
In the following description, the communication network shall perform communication in accordance with the LTE (Long Term Evolution) communication standard.

The communication network NET interconnects with another connection carrier communication network ENET via a gateway switch (Interconnecting Gateway Switch) (not shown), and a mobile phone, a smartphone, etc. belonging to the connection carrier corresponding to the communication network NET. A core network CNET that controls the connection of mobile communication terminals, a plurality of base station control devices BSC that are connected to the core network CNET and manage and control base stations, which will be described later, and a coaxial cable LC to each base station control device BSC. It is equipped with a plurality of wireless base stations BTS connected by wire.

In the above configuration, the base station control device BSC includes a coaxial transmission device 10A, the radio base station BTS includes a coaxial transmission device 10B, and the coaxial transmission device 10A and the coaxial transmission device 10B are arranged to face each other via a coaxial cable. ..

Next, the coaxial transmission device will be described.
Since the coaxial transmission device 10A and the coaxial transmission device 10B have the same configuration, the coaxial transmission device 10A will be described as an example.

FIG. 2 is a schematic block diagram of the coaxial transmission device.
The coaxial transmission device 10A is a device that performs Ethernet (registered trademark) communication, and can be roughly classified into a network interface unit 11, a switch unit 12, a first modulation / demodulation device 13, and a first analog digital converter (AD / DA). ) 14, a first transmitter / receiver 15, a second modulator / demodulator 16, a second analog-digital converter 17, a second transmitter / receiver 18, and a composite distributor 19.

In the following description of the coaxial transmission device, for convenience, the case where data is transmitted from the network interface unit 11 side to the composite distributor 19 side is called a downlink, and conversely, the case where data is transmitted from the composite distributor 19 side to the network interface unit 11 side is called a downlink. The case where data is transmitted is called an uplink.

The network interface unit 11 is configured as, for example, 1000BASE-T, and receives an Ethernet frame (= packet data) from the outside (in this case, the core network CNET) at the time of downlink and outputs the Ethernet frame (= packet data) to the switch unit 12. Further, the network interface unit 11 transmits the data output by the switch unit 12 to the outside (in this case, the core network CNET) as an Ethernet frame at the time of uplink.

At the time of downlink, the switch unit 12 filters (separates) PTP (Precision Time Protocol) packet data and other data at the layer 2 or layer 3 level from the Ethernet frame transmitted from the core network CNET output by the network interface unit 11. Then, the PTP packet data is output to the second modulation / demodulation device 16, and other packet data is output to the first modulation / demodulation device 13. Further, at the time of uplink, the switch unit 12 outputs packet data other than the PTP packet output by the first modulation / demodulation device 13 and PTP packet data output by the second modulation / demodulation device 16 to the network interface unit 11 as a series of packet data. ..

In this case, as a filtering method, a method of separating PTP packets and packets of a mobile communication terminal such as a mobile phone by a VLAN Tag or the like assigned on the core network CNET side, a method of separating by a UDP port number, or the like is used. Can be mentioned.

Here, PTP packet data will be described.
The PTP packet data is the data specified in IEEE1588, and highly accurate time information is accurately transferred from the master clock, which is the reference of the time information, to the client clock via the asynchronous packet network.

By the way, in order to transfer highly accurate time information, it is necessary that the communication circuit has symmetry between the uplink and the downlink.
Therefore, in the present embodiment, the FDD type wired transmission method is adopted for the communication of PTP packet data.

FIG. 3 is an explanatory diagram of an example of frequency allocation to PTP packet data and other packet data.
For PTP packet data, a first frequency band having a center frequency f1 for transmission and a second frequency band having a center frequency f2 for reception are assigned as transmission frequencies.
For other packet data, a third frequency band of the center frequency f3 for transmission / reception is assigned as a transmission frequency in order to perform data communication in the TDD system.

Furthermore, for PTP packet data, considering the transmission speed in the uplink and downlink, the modulation rate and down at the time of uplink are used as a fixed modulation rate without using applied modulation (adaptive modulation) that changes the modulation rate. The modulation rate at the time of linking is the same. Further, as the modulation method, for example, it is preferable to use a modulation method such as BPSK (Binary Phase Shift Keying) having a low modulation rate and a low error rate even with the same C / N (Carrier to Noise ratio). This suppresses retransmission due to the occurrence of an error. Furthermore, in the transmission and reception of PTP packet data, the transmission power is set so as to obtain a desired C / N.

At the time of downlink, when other packet data other than PTP packet data is input from the switch unit 12, the first modulation / demodulation device 13 becomes a signal that can be transmitted via the coaxial cable based on the input other packet data. It is modulated and output to the first analog-digital converter 14. Examples of the modulation method in this case include BPSK, QPSK (Quadrature Phase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), 64QAM (64 Quadrature Amplitude Modulation) and the like. Further, at the time of uplink, the first modulation / demodulation device 13 demodulates other packet data input from the first analog digital converter 14 into a signal that can be transmitted via the network interface unit 11 and outputs the data to the switch unit 12. ..

At the time of downlink, the first analog-to-digital converter 14 performs digital-analog conversion of the modulation signal output by the first modulation / demodulation device 13 and outputs it to the first transmitter / receiver 15 as a transmission signal. At the time of uplink, the first analog-to-digital converter 14 performs analog-digital conversion of the received signal output by the first transmitter / receiver 15 and outputs the received data to the first modulation / demodulator 13.

The first transmitter / receiver 15 is a transmitter / receiver that performs TDD transmission / reception using the third frequency band of the center frequency f3 described above, and at the time of downlink, generates a transmission signal and outputs it to the composite distributor 19. Further, at the time of uplink, the first transmitter / receiver 15 receives a received signal corresponding to other packet data other than the PTP packet data distributed by the synthetic distributor and outputs the received signal to the first analog-digital converter 14.

When the PTP packet data is input from the switch unit 12 at the time of downlink, the second modulation / demodulation device 16 modulates the PTP packet data into a signal that can be transmitted via the coaxial cable based on the input PTP packet data, and the second analog digital Output to the converter 17. Examples of the modulation method in this case include a modulation method having a low modulation rate such as BPSK and a low error rate even with the same C / N. Further, at the time of uplink, the second modulation / demodulation device 16 demodulates the PTP packet data input from the second analog digital converter 17 into a signal that can be transmitted via the network interface unit 11 and outputs the PTP packet data to the switch unit 12.

At the time of downlink, the second analog-to-digital converter 17 performs digital-analog conversion of the modulation signal output by the second modulation / demodulation device 16 and outputs it to the second transmitter / receiver 18 as a transmission signal. At the time of uplink, the second analog-to-digital converter 17 performs analog-digital conversion of the received signal output by the second transmitter / receiver 18 and outputs the received data to the second modulation / demodulator 16.

The second transmitter / receiver 18 is a transmitter / receiver that performs FDD-type transmission / reception using the first frequency band of the center frequency f1 and the second frequency band of the center frequency f2 described above, and generates a transmission signal at the time of downlink. , Output to the composite distributor 19. Further, at the time of uplink, the second transmitter / receiver 18 receives the received signal corresponding to the PTP packet data distributed by the composite distributor and outputs the received signal to the second analog-digital converter 17.

At the time of downlink, the composite distributor 19 synthesizes the transmission signal output by the first transmitter / receiver 15 (frequency band of the center frequency f3) and the transmission signal output by the second transmitter / receiver 18 (frequency band of the center frequency f1). Is transmitted to the coaxial transmission device 10B via the coaxial cable. Further, the composite distributor 19 receives the received signal received from the coaxial transmission device 10B via the coaxial cable at the time of uplink, and the received signal in the frequency band corresponding to the PTP packet data (frequency band of the center frequency f2) and the PTP packet data. The received signal in the frequency band (center frequency f3 frequency band) corresponding to other packet data is separated into, and the received signal in the frequency band corresponding to the PTP packet data (center frequency f2 frequency band) is seconded. It is output to the transmitter / receiver 18, and the reception signal of the frequency band (frequency band of the central frequency f3) corresponding to other packet data is output to the first transmitter / receiver 15.

Therefore, to summarize the above, the master device (not shown) of the core network CNET is the network interface unit 11 of the coaxial transmission device 10A → the switch unit 12 of the coaxial transmission device 10A → the second modulation / demodulation device 16 of the coaxial transmission device 10A → the coaxial transmission device. 2nd analog digital converter 17 of 10A → 2nd transmitter / receiver 18 of coaxial transmission device 10A → composite distributor 19 of coaxial transmission device 10A → coaxial cable → composite distributor 19 of coaxial transmission device 10B → first of coaxial transmission device 10B 2 Transmitter 18 → 2nd analog digital converter 17 of coaxial transmission device 10B → 2nd modulation / demodulation device 16 of coaxial transmission device 10B → switch section 12 of coaxial transmission device 10B → network interface section 11 of coaxial transmission device 10B The PTP packet data is transmitted to the radio base station BTS.

Similarly, the radio base station BTS is directed from the network interface unit 11 of the coaxial transmission device 10B toward the network interface unit 11 of the coaxial transmission device 10A in the reverse order of the above-mentioned order with respect to the master device (not shown) of the core network CNET. And transmits PTP packet data.

The time synchronization processing procedure will be described by exchanging PTP packet data actually performed via the above-mentioned PTP packet data transmission path.

FIG. 4 is an explanatory diagram of a time synchronization processing procedure by PTP.
First, at time t0, the master device (not shown) of the core network CNET transmits an Announce Message AM for notifying the time synchronization accuracy information to the radio base station BTS which is a slave device.

As a result, the radio base station BTS grasps that the time synchronization accuracy information is subsequently transmitted within a predetermined time.

Subsequently, at time t1, a master device (not shown) of the core network CNET transmits a Sync Message SM as an event message to the radio base station BTS.
In this case, the sync message SM records the time t1, which is the transmission time of the sync message SM.

Then, at time t2, when the radio base station BTS receives the sync message SM, it records the reception time t2.

Further, the radio base station BTS transmits a delay request message (Delay_Request_Message) DRM in order to notify a master device (not shown) of the core network CNET that the sync message SM has been received at time t3.
In this case, the delay request message DRQM records the time t3, which is the transmission time of the delay request message DRM.

Then, at time t4, when the radio base station BTS receives the delay request message DRM, it records the reception time t4.
Further, a master device (not shown) of the core network CNET transmits a delay response message DRPM recording the reception time t4 of the delay request message DRM to the radio base station BTS.

Next, a method of calculating the time difference in the above state will be described.
Here, it is assumed that the clock time of the radio base station BTS and the clock time of the master device (not shown) of the core network CNET are offset by the offset time TOF1.

Therefore, in the case of the above example, the time difference from the master device (not shown) of the core network CNET to the radio base station BTS (slave) and the time difference from the radio base station BTS (slave) to the master device (not shown) of the core network CNET. When the transmission delay time DLY1 is the same in any direction, the following relationship is established.

-Time difference in the direction of the wireless base station BTS (slave) from the master device (not shown) of the core network CNET t2-t1 = DLY1 + TOF1 ... (1)
-Time difference from the radio base station BTS (slave) to the master device direction of the core network CNET (not shown) t4-t3 = DLY1-TOF ... (2)

As a result, the radio base station BTS (slave) calculates the transmission delay time DLY1 from the sum of the equations (1) and (2), and the offset time TOF1 from the difference between the equations (1) and (2). Is calculated.

That is,
DLY1 = ((t2-t1) + (t4-t3)) / 2 ... (3)
TOF1 = ((t2-t1)-(t4-t3)) / 2 ... (4)
As a result, the radio base station BTS constantly corrects the time in the radio base station BTS based on the calculated transmission delay time DLY and offset time TOF1, and realizes highly accurate time synchronization. ..

As described above, according to the first embodiment, the coaxial transmission device 10A and the coaxial transmission device 10B are PTP packet data between the master and the slave asynchronously with other packet data transmitted in parallel at the same time. Can be transmitted via a transmission path separate from other packet data, and the uplink and downlink can be transmitted in a symmetrical state.
Therefore, it is possible to perform highly accurate time synchronization and maintain that state.

[2] Second Embodiment The above first embodiment is an embodiment in an upper communication network which is a communication network between a core network and a radio base station, but this second embodiment is a core network. , This is an embodiment in the case of performing time synchronization with a radio base station connected to this core network via a repeater device.

FIG. 5 is a schematic block diagram of the repeater device of the second embodiment.
In FIG. 5, for the sake of easy understanding, a case where one master unit and two slave units connected to the master unit by a coaxial cable are described as an example of the repeater device will be described.

The communication system 30 is roughly divided into a core network CNET, a first base station 31 directly connected to the core network, and both the core network CNET and the first base station connected via different communication paths. The master unit 32, the two slave units 33-1 and 33-2 connected to the master unit 32 by a coaxial cable, and the second base connected to the slave unit 33-1 via a communication network, respectively. It has a station 34 and.

The master unit 32 is roughly classified into an RF interface (IF) 41, a frequency conversion unit 42, a first synthesis distributor 43, a network interface unit 44, a switch unit 45, a first modulation / demodulation device 46, and a first unit. 1 analog digital converter 47, first transmitter / receiver 48, second modulator / demodulator 49, second analog digital converter 50, second transmitter / receiver 51, second composite distributor 52, and third modulator / demodulator. 53, a third analog digital converter 54, a third transmitter / receiver 55, a fourth modulator / demodulator 56, a fourth analog digital converter 57, a fourth transmitter / receiver 58, a third composite distributor 59, and the like. It has.

Next, the slave unit 33-1 and the slave unit 33-2 will be described.
Here, since the slave unit 33-1 and the slave unit 33-2 have the same configuration, the slave unit 33-1 will be described as an example.

The slave units 33-1 are roughly classified into a composite distributor 61 connected to the second composite distributor 52 of the master unit 32 via a coaxial cable, a frequency conversion unit 62, a first transceiver 63, and a first transmitter / receiver 63. 2 transceiver 64, 1st analog digital converter 65, 1st modulator / demodulator 66, 3rd transceiver 67, 2nd analog digital converter 68, 2nd modulator / demodulator 69, switch unit 70, It includes a network interface unit 71.

Next, the outline operation of the second embodiment will be described.
The radio signal transmitted from the core network CNET is used as a transmission signal in the corresponding frequency band (center frequency f4 frequency band) in the path of the first base station 31 → RF interface (IF) 41 → first synthesis distributor 43. It is transmitted to the second synthetic distributor 52.

On the other hand, among the packet data (PTP packet data and other packet data) directly transmitted from the core network CNET via the wired communication network, the other packet data which is the packet data to be transmitted to the slave unit 33-1 is A frequency band (transmitted to the first modulation / demodulation device 46 via the path of the network interface unit 44 → the switch unit 45, and further via the first analog digital converter 65 and the first modulation / demodulation device 66, corresponding to other packet data. It is transmitted to the second composite distributor 52 as a transmission signal of the central frequency f3).

Further, among the packet data (PTP packet data and other packet data) directly transmitted from the core network CNET via the wired communication network, the PTP packet data which is the packet data to be transmitted to the slave unit 33-1 is the network. The frequency band (center frequency) corresponding to the PTP packet data is transmitted to the second modulation / demodulation device 49 via the path of the interface unit 44 → the switch unit 45, and further via the second analog digital converter 68 and the second modulation / demodulation device 69. It is transmitted to the second composite distributor 52 as a transmission signal of the frequency band of f1).

As a result, the second synthesis distributor 52 synthesizes the transmission signal in the frequency band of the center frequency f1, the transmission signal in the frequency band of the center frequency f3, and the transmission signal in the frequency band of the center frequency f4, and synthesizes the slave unit 33-1. Is transmitted via a coaxial cable.

The composite distributor 61 of the slave unit 33-1 outputs the transmission signal of the frequency band of the center frequency f4 among the transmission signals received from the master unit 32 to the frequency conversion unit 62.
The frequency conversion unit 62 converts the communication frequency into a communication frequency of a mobile terminal device (not shown), and communicates with the mobile terminal device via the first transceiver 63 and an antenna (not shown).

Further, the synthesis distributor 61 outputs a transmission signal (corresponding to other packet data) in the frequency band of the center frequency f3 among the transmission signals received from the master unit 32 to the second transmitter / receiver 64, and outputs the second transmitter / receiver. 64 outputs the received signal to the first analog-to-digital converter 65.

The first analog-digital converter 65 performs analog-digital conversion of the received signal output by the second transmitter / receiver 64 and outputs the received data to the first modulation / demodulator 66.
As a result, the first modulation / demodulation device 66 demodulates the received data and outputs it to the switch unit 70 as other packet data.

On the other hand, the synthesis distributor 61 outputs a transmission signal (corresponding to PTP packet data) in the frequency band of the center frequency f1 among the transmission signals received from the master unit 32 to the third transmitter / receiver 67, and outputs the transmission signal to the third transmitter / receiver 67. Outputs the received signal to the second analog-to-digital converter 68.

The second analog-to-digital converter 68 performs analog-digital conversion of the received signal output by the second transmitter / receiver 64 and outputs the received data to the second modulation / demodulator 69.
As a result, the second modulation / demodulation device 69 demodulates the received data and outputs it to the switch unit 70 as PTP packet data.

As a result, the switch unit 70 outputs PTP packet data and other packet data to the second base station via the network interface unit 71.

The above is the case where the PTP packet data is transmitted from the master device (not shown) of the core network CNET to the slave second base station, but next, the core network CNET is transmitted from the slave second base station. An outline of the operation when the PTP packet data is transmitted to a master device (not shown) will be described.

When the second base station 34 transmits PTP packet data to a master device (not shown) of the core network CNET, the network interface unit 71 → switch unit 70 → second modulation / demodulation device 69 → second analog digital converter 68. → 3rd transmitter / receiver 67 → Synthetic distributor 61 → Coaxial cable → 2nd synthetic distributor of master unit 32 → 2nd transmitter / receiver 51 → 2nd analog digital converter → 2nd modulation / demodulator 49 → Switch section 45 → Network interface PTP packet data is transmitted to a master device (not shown) of the core network CNET in the order of unit 44.

As a result, the master device and the second base station 34 (not shown) of the core network CNET can perform high-precision time synchronization in the procedure as shown in FIG. 3 and maintain the state.

In the above description, the case where the frequency band (band) used for communication is constant has been described, but the PTP packet data and other packet data use different frequency bands, and the FDD method is used for the PTP packet data. By using the data, if the uplink transmission line and the downlink transmission line can be configured symmetrically, it is possible to appropriately use an arbitrary frequency band.

The communication relay device of the present embodiment includes a control device such as a CPU, a storage device such as a ROM (Read Only Memory) and a RAM, an external storage device such as an HDD and a CD drive device, and a display device such as a display device. It is equipped with input devices such as a keyboard and mouse, and has a hardware configuration that uses a normal computer.

The program executed by the communication relay device of the present embodiment is provided by being recorded in a computer-readable recording medium such as a CD-ROM, a DVD, or a USB memory in an installable format or an executable format file. ..

Further, the program executed by the communication relay device of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by downloading via the network. Further, the program executed by the communication relay device of the present embodiment may be configured to be provided or distributed via a network such as the Internet.
Further, the program of the communication relay device of the present embodiment may be configured to be provided by incorporating it into a ROM or the like in advance.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

For example, although LTE signals have been taken up in the above description, the present invention can also be applied to other wireless communication signals such as WiMAX signals and wireless LAN signals.

10A, 10B Coaxial transmission device 11 Network interface section 12 Switch section 13 1st modulation / demodulation device 14 1st analog digital converter 15 1st transmitter / receiver 16 2nd modulation / demodulator 17 2nd analog digital converter 18 2nd transmitter / receiver 19 Composite distribution Device 30 Communication system 31 1st base station 32 Master unit 33 Slave unit 34 2nd base station 42 Frequency conversion unit 43 1st synthesis distributor 44 Network interface unit 45 Switch unit 46 1st modulation / demodulation device 47 1st analog digital converter 48 1st transmitter / receiver 49 2nd modulation / demodulator 50 2nd analog digital converter 51 2nd transmitter / receiver 52 2nd synthesis distributor 53 3rd modulation / demodulator 54 3rd analog digital converter 55 3rd transmitter / receiver 56 4th modulation / demodulator 57 4th analog digital converter 58 4th transmitter / receiver 59 3rd composite distributor 61 Composite distributor 62 Frequency converter 63 1st transmitter / receiver 64 2nd transmitter / receiver 65 1st analog digital converter 66 1st modulation / demodulator 67 3rd Transmitter / receiver 68 2nd analog digital converter 69 2nd modulation / demodulator 70 Switch section 71 Network interface section BSC base station controller BTS radio base station CNET core network LC coaxial cable

Claims (5)

A signal transmission device that transmits signals using the TDD method.
A switch unit that separates the time synchronization signal included in the input transmission signal from signals other than the time synchronization signal, and a switch unit.
A first transmission line that transmits signals other than the time synchronization signal,
The second transmission line that transmits the time synchronization signal and
A composite distributor that synthesizes a transmission signal from the first transmission line and a transmission signal from the second transmission line side, and distributes a transmission signal to the first transmission line side and a transmission signal to the second transmission line side.
A signal transmission device equipped with. The first transmission line includes a first modulation / demodulator that performs modulation / demodulation of signals other than the time synchronization signal, a first analog / digital converter that performs mutual conversion between an analog signal and a digital signal, and a first transmitter / receiver. Are serially connected in sequence,
The second transmission line includes a second modulation / demodulator that performs modulation / demodulation of signals other than the time synchronization signal, a second analog / digital converter that performs mutual conversion between an analog signal and a digital signal, and a second transmitter / receiver. Are sequentially serially connected,
The signal transmission device according to claim 1. The second transmission line is configured to transmit signals by the FDD method.
The signal transmission device according to claim 2. The signal transmission device according to any one of claims 1 to 3, which is a pair of signal transmission devices arranged so as to face each other via a communication cable.
A master device that is connected to one of the signal transmission devices and transmits time synchronization accuracy information that constitutes the time synchronization signal.
A slave device connected to the other signal transmission device and performing time correction based on the time synchronization accuracy information, and a slave device.
Signal transmission system with. A method executed by a signal transmission device having a first transmission line for transmitting a signal other than the time synchronization signal and a second transmission line for transmitting the time synchronization signal, and performing signal transmission by the TDD method. There,
The process of separating the time synchronization signal included in the input transmission signal and the signal other than the time synchronization signal, and
A process of transmitting a signal other than the time synchronization signal via the first transmission line and
The process of transmitting the time synchronization signal via the second transmission line and
Depending on the transmission direction, the transmission signal from the first transmission line and the transmission signal from the second transmission line side are combined, or the transmission signal to the first transmission line side and the transmission signal to the second transmission line side are distributed. And the process of doing
Method with.

Images