JPH11136192A - Optical communication system in pds system and its communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform normal reception even if a dynamic range of receiving part of a slave station is narrow and to construct an inexpensive system by adjusting an optical signal transmitting level outputted from a master station at each slave station and making optical signal receiving levels in each slave station that has different transmission loss respectively constant. SOLUTION: Communication between a master station and each slave station uses an optical burst signal. The station A receives the optical burst signal from a slave station Bn at an 0/E part 3A, converts it into an electric signal and sends it to a TDMA receiving part 4A. A level information detecting part 8A detects information of an optical receiving level that is notified from the station Bn from a signal that is sent to the part 4A and notifies the degree of power deterioration due to transmission loss to an optical transmission level controlling part 9A. The part 9A operates a variable ATT 7A which should adjust an optical transmission level to each slave station based on the information and performs control so that an optical receiving level at the station Bn may be an appropriate level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PDS (Passive D
ouble Star) type optical communication system and its communication method,
In particular, it relates to the adjustment of the optical reception level in each slave station.

[0002]

2. Description of the Related Art When optical transmission is performed between a master station and a plurality of slave stations by the PDS method, the slave stations are scattered at various places, so that the transmission distance between the master station and each slave station is different. Therefore, the transmission loss at the time of transmission differs for each slave station.

[0003] That is, as shown in FIG. 2, each slave station B ₁ ~
In the slave stations _Bn , the transmission distances to the master station A are different from each other, so that the transmission loss at the time of transmission is different, and the light reception level of the signal from each slave station in the master station A is different. Therefore, in the conventional optical communication system of the PDS system, each slave station B
To adjust to the light receiving level in the parent station A of the optical signal transmitted from the ₁ .about.B _n is constant, a method for controlling the optical transmission level is developed at each slave station B ₁ .about.B _n ing.

[0004]

As described above, the conventional P
In DS optical communication systems, a method has been developed to control the optical transmission level at each slave station in order to adjust the optical reception level at the master station of the optical signal transmitted from each slave station to be constant. However, the reception level mismatch due to the transmission loss also occurs in the communication from the master station to the slave station. However, in the communication from the master station to the slave station, there is no means for adjusting the level. Therefore, in each slave station, in order to cope with the difference in the optical reception level caused by the difference in transmission loss, the dynamic range of the receiving unit is widened. I had to keep it.

That is, in the optical communication system of the PDS system, since multiplexing is performed by TDMA, a burst signal is input from a slave station to a master station, but a normal continuous signal is transmitted from the master station to the slave station. The reason for this is that there is no means for adjusting the optical transmission level from the master station for each slave station.

For this reason, in each slave station, as shown in FIG.
Although the optical reception level is different, the transmission level from the master station cannot be adjusted to each slave station, so the slave station transmits the optical signal from the master station regardless of the distance from the master station. There has been a problem that the dynamic range of the receiving section must be widened in accordance with the system configuration in order to normally receive.

The present invention has been made to solve such a problem, and the level transmitted from the master station to each slave station is adjusted for each slave station, so that the dynamic range of the receiver of the slave station is narrowed. It is an object of the present invention to provide a PDS optical communication system and a communication method capable of performing normal reception even when the system is inexpensive and enabling construction of an inexpensive system.

[0008]

SUMMARY OF THE INVENTION A communication method for a PDS optical communication system according to the present invention is directed to a PDS (Passive Double Station) in which a master station and a plurality of slave stations are connected by a star coupler.
ar) In the communication method of the optical communication system, the optical burst signal corresponding to each slave station is also used for communication from the master station to the slave station, and the optical signal transmission level output from the master station is set to each slave station. The optical signal reception level at each slave station having a different transmission loss is made constant.

Also, in a communication method of an optical communication system of a PDS system in which a master station and a plurality of slave stations are connected by a star coupler, an optical communication system in which communication from the master station to the slave stations is made for each slave station. Using a burst signal, an optical signal is transmitted from the master station to each slave station, and each slave station detects the reception level of this optical signal and returns information on the reception level to the master station. The optical signal transmission level output from the master station is adjusted for each slave station based on the information on the reception level of the slave station, and the optical signal reception level at each slave station having a different transmission loss is made constant. And

If there is a newly added slave station, the level is sequentially increased from the low-level optical signal until the slave station returns the information of the reception level from the master station to the slave station, and repeats. When transmitting the optical signal and receiving a reply of the reception level from the slave station, the master station adjusts the optical signal transmission level to be output to the slave station based on the received reception level information of the slave station. Features.

Further, the optical communication system of the PDS system according to the present invention is an optical communication system of the PDS system in which a master station and a plurality of slave stations are connected by a star coupler. Using the optical burst signal corresponding to each slave station, the master station transmits an optical signal to each slave station, and each slave station detects the reception level of this optical signal and sends the information of the reception level to the master station. A reply unit, the master station includes an optical / electrical conversion unit that receives an optical signal and converts the optical signal into an electric signal, a TDMA receiving unit that receives an electric signal from the optical / electrical conversion unit,
A level information detecting section for detecting information on a reception level from each of the slave stations from a signal received by the DMA receiving section, a TDMA transmitting section for inputting transmission data and performing transmission control,
An electric / optical converter for inputting an electric signal from the MA transmitting unit and converting the electric signal to an optical signal; an optical variable attenuator for varying an optical transmission level from the electric / optical converter; An optical transmission level control unit that receives the information on the reception level returned from each slave station, controls the optical variable attenuator, and makes the optical signal reception level at each slave station having a different transmission loss constant. It is characterized by having.

Each of the slave stations receives an optical signal transmitted from the master station and converts it into an electric signal, and a TDM that receives the electric signal from the optical / electric converter.
A receiving section, an optical receiving level detecting section for detecting an optical receiving level received by the optical / electrical converting section, a TDMA transmitting section for inputting transmission data and controlling transmission, and transmitting an electric signal from the TDMA transmitting section. An electrical / optical converter for inputting and converting the optical signal into an optical signal; detecting an optical signal reception level and returning information on the reception level to the master station;

Further, each of the slave stations has an optical variable attenuator for varying an optical transmission level from the electric / optical conversion section, and an optical reception level detected by the optical reception level detection section.
An optical transmission level control unit for controlling the optical variable attenuator to adjust the optical signal transmission level to the master station is further provided.

The optical communication system of the PDS system and the communication method of the present invention having the above-described configuration allow the level of an optical signal transmitted from the master station to each slave station to be different for each slave station having a different transmission loss. It can be adjusted properly.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, A is a master station, B ₁ ,
B ₂ ,..., B _n are slave stations, 1 A, 1 B are 1: n, n: 1 star couplers, 2 A is an optical transmission line for communication from the master station to each slave station, and 2 B is each slave station. This is an optical transmission line for performing communication from the station to the master station.

The master station A has an O / E unit (optical / electrical conversion unit) 3A composed of a photodiode (PD) for receiving an optical signal from the optical transmission line 2B and converting it into an electric signal.
/ E TDMA receiver 4 for receiving an electric signal from unit 3A
A, a TDMA transmitting unit 5A that performs transmission control,
E / O section (electric / optical conversion section) 6A composed of a laser diode (LD) or the like for converting an electric signal from transmitting section 5A into an optical signal, and control of an optical transmission level transmitted from E / O section 6A. Variable attenuator (variable ATT) 7A, which performs level information, a level information detector 8A that detects level information (described later) notified from the slave station from a TDMA receiver 4A, and information detected by the level information detector 8A. Variable ATT7A
Is configured by an optical transmission level control unit 9A that performs the above control.

Each of the slave stations B _{1 to} B _n receives an optical signal from the optical transmission line 2A and converts it into an electric signal.
Unit 3B, T for receiving an electric signal from O / E unit 3B
DMA receiving unit 4B, TDMA for controlling transmission to master station A
A transmitting section 5B, an E / O section 6B for converting an electric signal from the TDMA transmitting section 5B into an optical signal, and an optical receiving level detecting section 7 for detecting an optical receiving level in the O / E section 3B.
B.

Next, the operation of the optical communication system configured as described above will be described. PDS as shown in FIG.
In the configuration, in the optical communication system of the present embodiment, communication between the master station A and each slave station is performed by a communication signal (uplink signal) from the slave station to the master station and a communication signal (downlink signal) from the master station to the slave station. 2) Both use optical burst signals. First, in the slave station _Bn , the optical burst signal from the master station A is received by the O / E section 3B, the received optical signal is converted into an electric signal, and the TDMA receiving section 4B
Send to At this time, in the optical reception level detection unit 7B,
The O / E unit 3B detects the level of the received optical signal and notifies this information to the TDMA transmitting unit 5B. The information on the optical reception level is reported from the TDMA transmitting unit 5B to the master station A via the E / O unit 6B.

On the other hand, in the master station A, the slave station B is controlled by the O / E section 3A.
_It receives the optical burst signal from _n , converts it into an electric signal, and transmits it to the TDMA receiver 4A. Level information detector 8A
Detects the information of the optical reception level notified from the slave station _Bn from the signal transmitted to the TDMA receiver 4A, and notifies the optical transmission level controller 9A of the degree of power deterioration due to transmission loss. The optical transmission level control unit 9A operates the variable ATT 7A to adjust the optical transmission level to each slave station based on this information, so that the optical reception level at the slave station _Bn becomes an appropriate level. Control.

That is, in the present embodiment, the communication from the master station to the slave stations uses an optical burst signal corresponding to each slave station, and the transmission level is changed for each slave station. The transmission level of each station can be adjusted to an appropriate level in each of the slave stations having different transmission distances and different transmission losses, thereby eliminating the need to widen the dynamic range of the receiving section of each slave station. Thus, a communication system can be constructed at low cost.

When there is a newly added slave station, the transmission level of the initial joining command from the master station is first transmitted at a low level in consideration of the narrow dynamic range of the slave station at the time of joining, and the response is returned. If not, the transmission level is gradually increased, and transmission is repeated while increasing the transmission level until a response is received from the slave station.

The configuration of the slave station described in the above embodiment is similar to the master station, except that an optical variable attenuator (not shown) for varying the optical transmission level from the E / O section and this optical reception level If an optical transmission level control unit (not shown) for controlling the optical variable attenuator and adjusting the optical signal transmission level to the master station based on the optical reception level detected by the detection unit 7B is added,
Similarly to the known technique, the optical reception level of the optical signal transmitted from each slave station at the master station can be made constant.

[0023]

As described above, the optical communication system of the PDS system and the communication method of the present invention use an optical burst signal corresponding to each slave station for communication from the master station to the slave station. By adjusting for each slave station, the reception level in each slave station having a different transmission loss can be made appropriate, and even if the dynamic range of the receiver of the slave station is narrow, a signal of an appropriate level can be received in each slave station. As a result, there is an effect that an inexpensive system can be constructed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of the present invention.

FIG. 2 is a diagram illustrating a system configuration of an optical communication system of a PDS system.

FIG. 3 is a diagram for explaining a problem of a conventional PDS optical communication method.

[Explanation of symbols]

A master station B ₁ , B ₂ ,... B _n slave stations 1A, 1B Star coupler 2A, 2B Optical transmission path 3A, 3B O / E section (optical / electrical conversion section) 4A, 4B TDMA receiving section 5A, 5B TDMA transmission section 6A, 6B E / O section (electrical / optical conversion section) 7A Variable optical attenuator 7B Optical reception level detection section 8A Level information detection section 9A Optical transmission level control section

Claims (6)

[Claims] 1. A communication method for a PDS (Passive Double Star) optical communication system in which a master station and a plurality of slave stations are connected by a star coupler. By using the optical burst signal corresponding to the above, the optical signal transmission level output from the master station is adjusted for each slave station, and the optical signal reception level at each slave station having a different transmission loss is kept constant. A communication method for a PDS optical communication system. 2. A communication method of an optical communication system of a PDS system in which a master station and a plurality of slave stations are connected by a star coupler, wherein the communication from the master station to the slave stations corresponds to each slave station. Using a burst signal, an optical signal is transmitted from the master station to each slave station, each slave station detects the reception level of this optical signal, and returns information on the reception level to the master station. The optical signal transmission level output from the master station is adjusted for each slave station based on the information on the reception level of the slave station, and the optical signal reception level at each slave station having a different transmission loss is made constant. A communication method of an optical communication system of a PDS system. 3. When there is a newly added slave station, the level is sequentially increased from the low-level optical signal until the slave station returns the information of the reception level from the master station to the slave station. When transmitting the optical signal and receiving a reply of the reception level from the slave station, the master station adjusts the optical signal transmission level to be output to the slave station based on the received reception level information of the slave station. 3. The communication method for a PDS optical communication system according to claim 2, wherein: 4. In a PDS optical communication system in which a master station and a plurality of slave stations are connected by a star coupler, an optical burst signal corresponding to each slave station for communication from the master station to the slave stations is provided. Means for transmitting an optical signal from the master station to each slave station, detecting the reception level of this optical signal at each slave station, and returning information on the reception level to the master station; An optical / electrical conversion unit for receiving a signal and converting it to an electric signal; a TDMA receiving unit for receiving an electric signal from the optical / electrical conversion unit; A level information detection unit for detecting information of a reception level, a TDMA transmission unit for inputting transmission data and performing transmission control, an electric / optical conversion unit for inputting an electric signal from the TDMA transmission unit and converting the electric signal to an optical signal, Changing the optical transmission level from the electrical / optical converter Optical variable attenuator, The information of the reception level returned from each slave station detected from the level information detection unit is input, and the variable optical attenuator is controlled, and each of the slave stations having a different transmission loss. An optical communication system of a PDS system, comprising: an optical transmission level control unit for making an optical signal reception level constant. 5. An optical / electrical conversion unit for receiving an optical signal transmitted from the master station and converting the optical signal into an electric signal, and a TDMA for receiving an electric signal from the optical / electrical conversion unit. A receiving unit; an optical receiving level detecting unit for detecting an optical receiving level received by the optical / electrical converting unit; a TDMA transmitting unit for inputting transmission data and controlling transmission; and receiving an electric signal from the TDMA transmitting unit 5. An optical communication system according to claim 4, further comprising an electrical / optical converter for converting the received signal into an optical signal, wherein the optical signal is detected and the information on the received level is returned to the master station. . 6. An optical variable attenuator for varying an optical transmission level from the electric / optical conversion section, and the optical station based on an optical reception level detected by the optical reception level detection section. 6. The optical communication system according to claim 5, further comprising: an optical transmission level control unit that controls a variable attenuator to adjust an optical signal transmission level to a master station.