JPS58187037A - Optical star network communication system - Google Patents

Abstract

PURPOSE:To improve the operating efficiency of a network, by transmitting a signal from a terminal device to a star repeater by the light in another wavelength during the use of a network, storing the signal once and transmitting the signal to each terminal device when the network is idle. CONSTITUTION:When a transmission request comes from a terminal device 10, a transceiver 20 detects whether or not the network is busy at a collision detector 36, and when empty, signals are transmitted after being converted into a light in a wavelength lambda1 via a control circuit 22, converted into electric signals at a photo detector 56A of a star repeater 50, inverted into the light in wavelength lambda1 at a converter 78 via a multiplexer 62, and transmitted to the transceiver 20. When the network is busy, the output of the device 10 is converted into a light in wavelength lambda2 via the circuit 22, and transmitted after being synthesized with the light in the wavelength lambda1 at a filter 52. Further, the signal is stored in a memory 66 in the repeater 50 after being separated into the signal in the wavelength lambda1 at a filter 52. When the network is idle, the signal is transmitted to the device 20 via a control circuit 64.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical star network communication system, and particularly to an optical star network communication system using a star repeater that connects a plurality of optical fiber transmission lines in a star shape and performs regenerative relay.

Such a star network (star-shaped communication network) communication method is often used in local networks. Communication terminal devices (stations) of host combiners are connected to the optical fiber transmission line via transmitting/receiving devices, and each station communicates with other stations via star repeaters. The star repeater is
The optical signal received from one station is regenerated and relayed, and sent out to the optical transmission lines going to all other stations. Therefore, in the conventional system, while one station is transmitting, other stations cannot communicate, which reduces the efficiency of network usage.

In order to solve this problem, Japanese Patent Laid-Open No. 56-98948 discloses that a plurality of lights having different wavelengths are prepared as carriers of an optical transmission line.

An optical star network communication system is described in which communication is performed by selecting light of a wavelength that is not used for communication on the upper workpiece. This communication system requires a complicated circuit in each station to detect the wavelength of light that is being used in the network and to select light of an unused wavelength from among a plurality of wavelengths of light. Therefore, the equipment configuration of each station is complicated, and it is not a good idea to provide a large number of such stations in the network.

Therefore, an object of the present invention is to provide an optical star network communication system that eliminates the drawbacks of the conventional system and has a simple configuration and high network usage efficiency.

This objective is achieved according to the invention by an optical star network communication scheme as follows.

In other words, this system is an optical star network communication system in which multiple communication terminal devices are connected to a star repeater via an optical transmission path, and data is transmitted between the multiple communication terminal devices via the star repeater. The star repeater normally transmits data using light of the first wavelength, and when the light of the first wavelength is present on the optical transmission path from the star repeater, the communication terminal device transmits data using light of the first wavelength. Data is sent to a star repeater using light of a different second wavelength, and when data is sent from a communication terminal device using light of a second wavelength, the star repeater temporarily stores the data, and when the optical transmission line is free. The stored data is transmitted using light of the first wavelength when the wavelength is reached.

Next, the optical star network communication system according to the present invention will be explained in detail with reference to the accompanying drawings.

The figure is a block diagram showing an embodiment of the optical star network communication system according to the present invention. In this communication method, for example, N+1 communication terminal devices such as host converters, etc.
0 is connected to a star repeater 50 via N+1 transmitting/receiving devices 20 and N,11 pairs of optical fibers 40T and 4OR, forming a star-shaped communication network.

The terminal device IO is connected to the control circuit 22 of the transmitting/receiving device 2o through a transmitting line 12T and a receiving line 12R. The data outputs 24A and 24B of the control circuit 822 are electrical/optical (Elo) signals such as light emitting diodes, respectively.
Connected to transducers 26A and 26B. The E10 converters 26A and 26B are elements that generate lights of different wavelengths λ1 and λ2, respectively, and their optical outputs 28A and 28B are connected to the optical combiner 3°.

The output of the optical combiner 30 is connected to an optical fiber 40T on the transmission side.

- The optical fiber 4OR on the receiving side is connected to a wavelength detector 32, which in this example detects light with a wavelength of λ1 and converts it into an electrical signal. 0/E) converter. One output of the photodetector 32 is connected to a data input 34 of the control circuit 22, and the other output 35 is connected to a collision detector 36. The collision detector 36 is connected to the control circuit 22 by a control line 38, and is a circuit that detects a collision between transmission and reception of light of wavelength λ1 in this transmitting/receiving device.

Optical fibers 40T connected from each transmitter/receiver 2o to the star repeater 50 are coupled to a filter 52.

This filter 52 separates the light with the wavelength λl from the light with the wavelength λ2, and the light with the wavelength λ1 is incident on the photodetector 56A via the reflecting mirror 54 as shown in the figure, and the light with the wavelength λ2 is incident on the photodetector 56A. 56B. The photodetectors 56A and 56B each have an optical/electrical sensor such as a photodiode.
/E) converter, the photodetector 56A detects light with a wavelength λl and converts it into an electrical signal, and the photodetector 56B detects light with a wavelength λl and converts it into an electrical signal.
The second light is detected and converted into an electrical signal. Photodetector 56A
The output 58A of is connected on the one hand to a carrier detector 60 and on the other hand to a multiplexer 62. The carrier detector 60 detects the wavelength λ in the optical fiber 40T.
This circuit detects the presence or absence of light of 1, that is, a carrier, and notifies the control circuit 64 of this through the control line 62. The output 58B of the photodetector 56B is connected to a memory 66, and the memory 66 is a storage device that temporarily stores the light signal of wavelength λ2 detected by the photodetector 56B.

The data output cuff o of the control circuit 64 is connected to the multiplexer 62, and the output cuff 2 of the multiplexer 62 is connected to the amplifier 74.
It is connected to the. The output cuff 6 of the amplifier 74 is connected to an E10 converter 78, for example a light emitting diode. Multiplexer 62 outputs the output 58 of photodetector 56A.
This circuit sends either the signal sent from A or the signal sent from the data output cuff 0 of the control circuit 64 to the output cuff 2. The E10 converter 78 is a light emitting element, such as a light emitting diode, which generates light according to the electrical signal appearing at the output cuff 6 of the amplifier 74 to drive the receiving optical fiber 4OR. In this example, the wavelength of the light generated by the E10 converter 78 is the wavelength of the light generated by the E10 converter 26 of the transmitting/receiving device 20.
Although it is equal to the wavelength λl of the light generated by A, it is not necessarily necessary, and it may be any other wavelength, for example λ2. Note that the O/E converter 3 of the transmitter/receiver 20
The response wavelength of 2 is the E10 converter 7 of the star repeater 5o.
Needless to say, it is necessary to match the emission wavelength of No. 8.

By the way, when receiving a data transmission request from the terminal device 1o, the transmitting/receiving device 2o detects whether or not the network is in use at that time. This means that the collision detector 36 is the photodetector 32.
This is done by checking whether there is light of wavelength λ1, that is, a carrier, in the receiving side optical fiber 4OR via . When the collision detector 36 detects that the network is empty, the control circuit 22 connects the transmission line 12T from the floor device 10 to the data line 24A, and the collision detector 26A
to drive. Therefore, data is sent from the terminal device IO to the optical fiber 40T using light of wavelength λl.

In the star repeater 50, the transmission side optical fiber 40T
The light having the wavelength λl received from the filter 52 is sent to the photodetector 56A via the reflecting mirror 54. The photodetector 56A outputs an electrical signal corresponding to the received light having the wavelength λl to an output 58A. This output 58A signal is applied through multiplexer 62 and amplifier 74 to E10 converter 78. The signal converted into light having a wavelength λl by the E10 converter 78 is transmitted to all the transmitting/receiving devices 20 through the receiving optical fiber 4OR.

In the transmitting/receiving device 20, the light of wavelength λl received from the receiving side optical fiber 40R is detected by the photodetector 32 and sent to the control circuit 2.
The control circuit 22 sends this signal to the terminal device 10 through the reception line 12R. In this manner, communication between the terminal devices IO is performed via the star repeater 50.

By the way, when the control circuit 22 detects a transmission request from the terminal device 1O and detects that the network is in use via the collision detector 36, it detects that light of wavelength λ1 is being transmitted to the receiving side optical fiber 40R. Then, the transmission line 12T of the terminal device IO is connected to the data line 24B of the E10 converter 26B. As a result, E10 converter 26B is driven instead of E10 converter 26A, and E10 converter 26B transmits light of wavelength λ2 to transmission side optical fiber 40T through optical coupler 30 in response to the signal sent from terminal device 1o through transmission line 12T. Send.

The light of wavelength λ2 transmitted through the optical fiber 40T is
The photodetector 5 is detected by the filter 52 of the star repeater 5o.
Guided by 6B. Wavelength λ2 detected by photodetector 56B
A signal corresponding to the light is sent to the memory 6 through the data line 58B.
6 is written. In this way, the data sent to the star repeater 50 by the light of wavelength λ2 is temporarily stored in the memory 66. At this time, star repeater 5
0 is a transmission side optical fiber 40T from another transmitting/receiving device 20
A photodetector 56A receives a signal sent as light with a wavelength λ1 through the photodetector 56A.

Multiplexer 62. Amplifier 74 and E10 converter 7
8 to each receiving side optical fiber 40R, and the usage status of such network is reported to the control circuit 64 by the carrier detector 60. Therefore, when the relay of the signal using the light having the wavelength λl is completed, the light having the wavelength λl no longer enters the photodetector 56A, so the carrier detector 60 detects this and notifies the control circuit 64. As a result, the control circuit 64 starts reading the data stored in the memory 66. This data is transmitted from a certain transmitting/receiving device 20 to the star repeater 50 using light of wavelength λ2. Control circuit 64 sequentially reads this data stored in memory 66 and drives E10 converter 78 through multiplexer 62 and amplifier 74. The data read out from the memory 66 in this way is converted into an optical signal of wavelength λ1 by the E10 converter 78, and transmitted through the receiving optical fiber 4OR.
It is sent to each transmitting/receiving device 20. Each transmitting/receiving device 20 performs the same receiving operation as described above, and transfers this data to the terminal device 1.
Send to 0.

In the optical star network communication system according to the present invention, data is transmitted from the terminal device to the star repeater using light of a different wavelength while the network is in use, and the star repeater stores this data once and transmits it when the network is free. Send to each terminal device. This not only improves network usage efficiency, but also eliminates the need for terminal equipment such as transmitting and receiving equipment to select light of many different wavelengths and to temporarily store data for waiting for transmission. The device configuration on the side is simplified. Generally, there are a large number of terminal devices, so being able to provide such a function to the star repeater side instead of the terminal side simplifies the overall system configuration and reduces the cost. In addition, the duplexer is installed on the star repeater side rather than on the terminal side.Since the star repeater performs regenerative relaying, it can compensate for optical loss caused by installing the duplexer, and the communication distance can be reduced. It can also be successfully applied to long systems. Note that since the star repeater temporarily stores data in its memory, it can be configured to determine the importance of the stored data and identify communications with a high degree of @ production. In this way, when a highly important communication is received while the network is in use, the current communication may be disconnected and the highly important data may be transmitted preferentially.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of the optical star network communication system according to the present invention. 22... Control circuits 26A, 26B... Electricity/light (Elo) detector 32
...Optical/electrical (0/E) converter 36...Collision detector 52...Filters 56A, 56B...0/E converter 60...Carrier detector 62...Multiplexer 64... ...Control circuit 66...Memory 78...E10 converter patent applicant Ricoh Co., Ltd.

Claims (1)

[Claims] In an optical star network communication system in which a plurality of communication terminal devices are connected to a star repeater via an optical transmission path, and data is transmitted between the plurality of communication terminal devices via the star repeater, the star repeater includes: Normally, data is transmitted using light of a first wavelength, and the communication terminal device connects the first wavelength to the optical transmission path from the star repeater.
When there is light with a wavelength of An optical star network communication system characterized in that the data is temporarily stored when the optical transmission line is empty, and the stored data is transmitted using light of a first wavelength when the optical transmission line becomes empty.