JPS6251532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber communication system using one linear optical fiber for common transmission.

Conventionally, there has been a device of this type as shown in FIG. In this figure, 1 is an optical fiber transmission line, 2 is an optical branching coupler inserted into this optical fiber transmission line 1, and 3 is an optical directional coupler for sending and receiving separation connected to this optical branching coupler 2. , 4 to 8 are data stations connected to the optical fiber transmission line 1 via the optical branching coupler 2 and the optical directional coupler 3 for sending and receiving separation.

Next, the operation will be explained.

Each of the data stations 4 to 8 shares one optical fiber transmission line 1 and performs N-to-N mutual communication. An optical signal transmitted from one of the data stations 4 to 8 is coupled to the optical fiber transmission line 1 by the optical branch/coupler 2, and propagates in both left and right directions of the optical fiber transmission line 1. A part of the optical power of the optical signal propagating through the optical fiber transmission line 1 is branched at each optical branch/coupler 2 and sent to each data station 4-8. Data stations 4 to 8 extract and receive only signals addressed to their own stations. For N-to-N multiple access, for example, time division multiple access (TDMA) is used.
Burst mode communication using the Access) method is applied.

Since the conventional optical fiber communication system is as described above, the transmission loss from one data station to another data station changes depending on the number of optical branching couplers 2 that communicate.
If multiple access technology such as TDMA is applied here, the level of the optical signal arriving at one station from each station will vary greatly from transmitting station to transmitting station, making it extremely difficult to configure reception gain control etc. for the optical receiver. At the same time, the quality of the transmitted signal deteriorates.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it connects a new optical repeater to a common optical fiber transmission line, and all optical signals from each data station are transmitted once to this optical repeater. A method that eliminates fluctuations in the optical signal level at each data station and avoids difficulties in controlling reception gain by configuring the system so that it is relayed and amplified via a device and then distributed to other data stations in broadcast mode. is intended to provide. This invention will be explained below.

FIG. 2 shows an embodiment of the present invention. In Fig. 2, 1 is an optical fiber transmission line;
1 to 14 are optical branching couplers inserted into this optical fiber transmission line 1, and 3 are optical branching couplers 11 to 14.
14 is an optical directional coupler for transmitting/receiving separation connected by an optical fiber; 4 to 7 are the optical branching couplers 11 to 1;
4 and an optical directional coupler 3 to the optical fiber transmission line 1, and has a passive configuration that does not require an optical regenerative repeater function. 9 is an optical directional coupler connected to the optical fiber transmission line 1 for separating transmission and reception; 10 is coupled to the optical fiber transmission line 1 via the optical directional coupler 9, and is connected to each data station 4 to 7; This is an optical repeater that relays and amplifies the optical signal of 1 and sends the optical signal to the optical fiber transmission line 1 again.

Next, the operation will be explained.

In FIG. 2, optical signals of wavelength λ transmitted from data stations 4 to 7 pass through optical directional coupler 3 for sending and receiving separation,
4, the signal is coupled to the optical fiber transmission line 1, propagates within the optical fiber transmission line 1 in the right direction in the figure, passes through the optical directional coupler 9 for separating transmission and reception, and is received by the optical repeater 10. The received signal is relayed and amplified by the optical repeater 10, sent out again to the optical fiber transmission line 1, and propagated within the optical fiber transmission line 1 in the left direction in the figure. Optical fiber transmission line 1
A portion of the optical power of the optical signal propagating in the left direction is sequentially distributed to each data station 4-7 in each optical branching/coupling device 11-14.

At this time, the optical power from each data station 4 to 7 is appropriately controlled, or the optical branching and coupling ratio of the optical branching coupler 11 to 14 is set to a different value for each data station 4 to 7, and optimization is performed. By achieving this, the level of received light from each of the data stations 4 to 7 in the optical repeater 10 can be made constant regardless of the transmitting station, and the reception gain control mechanism of the optical receiver is simplified. As a method of controlling the optical transmission power, for example, by monitoring the level of light sent from the optical repeater 10, the optical transmission power at each data station 4 to 7 is adjusted according to the transmission loss up to the optical repeater 10. Power can be controlled.

On the other hand, the optical receivers in each data station 4 to 7 receive only the optical signal from the optical repeater 10, so there is no significant fluctuation in the reception level.
No difficulties arise in controlling receive gain. In particular, if the optical branch/coupling ratio of the optical branch/coupler 11 to 14 is optimized, the optical power can be supplied to each data station 4 to 7 almost equally, which improves the signal transmission quality of the entire system. The advantage is that you can expect improvement.

For signal multiple access, time division multiple access (TDMA) and frequency division multiple access (FDMA) are used.
Frequency Division Multiple Access) method,
Spread Frequency Multiple Access (SSMA)
It is possible to apply any method such as the multiple access method.

As an example, considering the application of TDMA method,
Each data station transmits its own signal in bursts based on a signal that serves as a reference for a frame transmitted by one of the stations, so that the transmission timings of each station do not overlap. The optical repeater 10 receives the optical burst signal train sent from each data station 4-7, relays and amplifies it, and sends it out again to each data station 4-7 as an optical burst signal. Each data station 4 to 7 extracts only the signal addressed to itself from the sent burst signal and receives it. The downlink signal from the optical repeater 10 does not necessarily need to be transmitted in burst mode, and may be transmitted in time division multiplexed mode in connected mode.

In the above embodiment, the optical repeater 10 is provided at one end of the linear optical fiber transmission line 1, but it may be installed at another position on the optical fiber transmission line 1. Furthermore, by inserting and installing a bidirectional optical repeater 10 at any location on the optical fiber transmission line 1,
It is possible to cope with an increase in the number of connected data stations and an extension of the optical fiber transmission path length. In addition, the optical branching coupler 1 at each data station 4 to 7
1 to 14 and the optical directional coupler 3 for transmitting/receiving separation are treated as independent components, but the same effect can be obtained even if they are integrated into an optical circuit component.

As explained in detail above, according to this invention,
By performing mutual communication between multiple connected data stations via an optical repeater,
Since the level of the optical signal arriving at the optical receiver of each station is made constant regardless of the originating station, there is an effect that there is no difficulty in controlling the reception gain as in the conventional system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a conventional optical fiber communication system, and FIG. 2 is a block diagram showing an embodiment of the present invention. In the figure, 1 is an optical fiber transmission line, 3 and 9 are optical directional couplers, 4 to 7 are data stations, 10 is an optical repeater, and 11 to 14 are optical branching couplers.
Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. One optical fiber transmission line arranged linearly, and each optical fiber transmission line connected to the optical fiber transmission line via a plurality of optical branching couplers and optical directional couplers for sending and receiving separation. It has a function of receiving optical signals from a plurality of passive data stations and each data station connected to the optical fiber transmission line, repeating and amplifying them, and then returning them as optical signals of the same optical wavelength. forming an optical fiber transmission system with an optical repeater, and performing mutual communication among multiple stations between the respective data stations once via the optical repeater;
An optical fiber communication system characterized in that the level of received light in the optical repeater is controlled to be constant regardless of the originating station. 2. The optical fiber according to claim 1, wherein the optical branching/coupling ratio of each optical branching/coupling device is set so that the received light level at the optical repeater is constant regardless of the originating station. Communication method. 3. The optical fiber communication system according to claim 1, wherein the power of transmitted light from each data station is controlled so that the level of received light at the optical repeater is constant regardless of the transmitting station. 4. The optical fiber communication system according to claim 1, wherein the optical repeater is provided with at least one bidirectional optical repeater amplifier at any location on the optical fiber transmission line.