JPS5890840A - Optical fiber multiple access communication system - Google Patents

Abstract

PURPOSE:To perform an optical fiber multiple access communication with high reliability, by providing duplicated optical fiber transmission lines in spiral. CONSTITUTION:Data terminals 31-35 are connected to duplicated optical fiber transmission lines 11, 12 in spiral via optical repeaters 41, 42 and optical branching couplers 21-28. The repeaters 41, 42 have functions which convert a transmission wavelength lambda1 into a reception wavelength lambda2, fold the signal back into the same fiber and transmit it between the repeaters. The terminals 31-35 normally perform by using the function of either one of the repeaters 41, 42 and if one of the repeaters 41, 42 is damaged, the mutual communication is done by using the other repeater exclusively. If the transmission lines 11, 12 are opened at terminals, the mutual transmission function of the repeaters 41, 42 can ensure the communication between terminals for all of the terminals.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber multiple access communication system using a duplicated optical fiber transmission line and an optical repeater.

Conventionally, there has been a device of this type as shown in FIG.

In this figure, 1 is an optical fiber transmission line, 2.3 is a wavelength-selective optical branch/coupler inserted into this optical fiber transmission M1m, and 4 to T are optical fiber transmission lines via the optical branch/coupler 2. a data station 8 coupled to line 1 for transmitting an optical signal of wavelength λ1 and for receiving an optical signal of wavelength λ;
is an optical repeater that is coupled to the optical fiber transmission w11 via the optical branching coupler 3, receives an optical signal of a certain wavelength, converts the received signal into an optical signal of a wavelength λ, and sends it out.

Next, the operation will be explained. Each data station 4~
The signal transmitted from T is sent out as a signal of wavelength λ, and is coupled to optical fiber transmission line 1 by optical branching coupler 2 . An optical signal having a wavelength λ propagating through the optical fiber transmission line 1 passes through the optical branching coupler 3 and is received at the optical repeater.

The received signal is relayed and amplified by the optical repeater 6, and sent out as an optical signal with a wavelength λ.
is coupled to the original fiber transmission line 1 by. An optical signal with a wavelength λ propagating to the optical fiber transmission W &1' has a part of its optical power branched to each of the data stations 4 to T in each of the six optical branching couplers 2, and the remaining optical power is transmitted directly to the optical fiber. The data propagates within the fiber transmission line 1 and is distributed to the data stations 4-1.

At this time, by setting the optical branching/coupling device of the optical branching/coupling device 2 to an optimal value for each data station 4 to 1, the received light level at the optical repeater 8 can be kept constant regardless of the originating station. In addition, since the optical receiver at each station receives only the signal from the optical repeater 8, there are no large fluctuations in the received light level (there are no difficulties in controlling the reception gain of both the optical repeater a and the optical receiver at each station). It has 5411 kv.

However, the conventional optical fiber multiple access communication system described above has problems in terms of 4Ii reliability, as communication becomes impossible if there is a failure in the optical repeater 8 or a break in the original fiber transmission line 1. Ta.

This invention was made in order to eliminate the above-mentioned 5 drawbacks of the conventional ones, and by duplicating the optical repeater and duplicating the optical fiber transmission line t#l spiral, highly reliable optical The purpose is to provide a fiber multiple access communication system. -Hereinafter, the present invention will be explained with reference to the drawings.

Figure 2 shows an embodiment of this invention, with 41.42
11.1 is an optical repeater that receives an optical signal of wavelength λ, converts the signal into an optical signal of wavelength λ, and sends it out;
2 is these two optical repeaters 41, 42' and the former fiber transmission line installed in a spiral duplex with a banker in the center.
21-28 are optical branching couplers inserted into the optical fiber transmission line 11.12, and 51-55 are the optical fiber transmission line 11. ．． 120 optical branching couplers 21 to 28Y: an optical transmitting and receiving unit that receives an optical signal with a wavelength λ1 or an optical signal with a transmission wavelength λ;
1 to 65 are data terminals including interfaces with the optical transmitting and receiving units 51 to 55 and information terminals; 31 to 3;
Reference numeral 5 denotes a data station composed of the optical transmitting/receiving units 51 to 55 and data terminals 61 to 65, respectively.

Next, the operation will be explained. In FIG. 2, during normal operation, two optical relay irons [41 and 42 are operated independently, and the wavelength λ
The optical signals of
8, duplicated optical fiber transmission line 11.12
be combined with either part of. After being relayed and amplified via the optical repeater 41 or 42 connected to the combined optical fiber transmission line and converted into an optical signal with a wavelength λ, the same optical fiber transmission line 11° 12Y is transmitted again. Propagates in the opposite direction. A part of the optical power of the optical signal having the wavelength λ from the optical repeater 41, 42 is branched in the optical branching/coupling devices 21 to 28 and distributed to each data station 31 to 35, resulting in so-called broadcast mode signal transmission. is realized.

Optical relay equipment that becomes a problem in the case of linear optical transmission lines 41.42
In the event of a failure such as a failure of the optical fiber transmission lines 11 or 12 or a disconnection of the optical fiber transmission lines 11 and 12, communication is continued in the following manner. First, to deal with the possibility of a failure in the optical repeater 41 or 42, by having the two optical repeaters 41 and 42' operate independently, even if a fault occurs in one of them, the other optical repeater will not be affected. The entire system can be operated using equipment. If one of the duplicated optical fiber transmissions 1311 and 12 is disconnected,
Communication continues through the remaining optical fiber transmission line.

Furthermore, as shown in FIG. 3, if the duplicated optical fiber transmission lines 1j and 12 are cut off at one point, for example at point 11, the two optical repeaters 41 and 42 will not be able to transmit each other's relay signals. The parts shown in bold in Figure 3 and the optical fiber transmission w1721' are used to send and receive data from each data station 31 to
N-to-N multiple access communication between the T.35 and the N.35 continues.

To multiplex the signal, TDM A (T im
@DiviaionMultiplemuee@ss
) system and FDM system (Fr@quencyDivlsio
In addition to the n Mtxltiple mce@se) method,
SSMA (8pr@ad 8p*etrum Mul
Tipl@Access) method and C8M/CD
(Carrier 8@nse Multipl@Ac
c@55w1th Co11ision Detect
It is possible to apply a random access communication method such as the iows) method.

- As an example, if we talk about the application of C8MA/CD,
After each data station 31 to 35 confirms by carrier detection that no other station is transmitting a signal, it transmits a series of data to which a destination station code is added as an optical signal of wavelength λ. This data is transmitted to optical repeaters 41 and 42 at wavelength λ.

After being converted into an optical signal, it is distributed to each station in broadcast mode, and is received only by the station that has identified the destination station code. If multiple stations transmit signals at the same time, indicating that no carrier exists, a signal collision will occur.
A transmitting station that detects a collision immediately stops transmitting and retransmits according to certain rules, thereby realizing highly dynamic communication.

When each station sends data, an optical repeater 41 to the destination station among the duplicated optical fiber transmission lines 11.12
．． When the optical transmitting/receiving unit performs control to couple the optical signal to the optical fiber transmission line with the shorter transmission path length via the optical fiber transmission line 42, the propagation delay time term due to passing through the optical repeaters 41 and 42 can be suppressed. and network responsiveness.

It is possible to increase both throughput.

The optical repeater 41. The light receiving level at 42 can be kept constant regardless of the transmitting station, and each optical transmitting/receiving unit 51 to
The level of light received from the optical repeater 1141.42 at 55 can also be configured to be constant.

Further, in the above embodiment, the optical repeaters 41 and 42 are installed separately from the data stations 31 to 35, but it is possible to provide the optical repeaters 41 and 42 with the function of one data station. In addition, different optical wavelengths were assigned to the transmitting light wavelength λ and the receiving light wavelength λ of each station, but if the separation of transmitted and received signals and the isolation of reflected light can be achieved sufficiently, it can be realized with a single wavelength as λ1 = λ1. is also possible.

As explained in detail above, according to the present invention, in an optical network where a plurality of data stations communicate with each other (via an IY party repeater only once), the optical repeater is redundant and the optical fiber transmission WI11 is connected in a spiral manner. Since the structure is made redundant, there is an effect that extremely high reliability can be obtained against failures of optical repeaters and disconnection failures of optical fibers.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional optical fiber multiple access communication system, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 explains the situation when a disconnection occurs in the embodiment of Fig. 2. This is a diagram for In the figure, 11.12 is the original fiber transmission line, 21-28 are optical branching couplers, 31-35 are data stations, 41.
42 is an optical repeater, 51 to 55 are optical transceiver units, and 6
1 to @5 are data terminals. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno (and 1 other person) Figure 1 Figure 3

Claims (1)

[Claims] +11 Two optical repeaters installed in close proximity to each other so as to be able to send and receive received signals, and the two optical repeaters i & 1l.
an optical transmission line in which two optical fibers are arranged in a spiral duplex sandwiched in the center of the IIt; a plurality of optical branching couplers inserted into both of the duplicated optical transmission lines; A fiber transmission system is configured with a plurality of data stations connected to the optical transmission line via a branching coupler, and two different optical wavelengths are assigned to the transmission source wavelength and reception optical wavelength of each data station, The optical repeater is equipped with a wavelength conversion function between these two optical wavelengths, and during normal operation, the two optical repeaters are operated independently, and each data station is connected to the two optical G* When one of the optical repeaters is in trouble, only the other is used for communication *vm.
Optical fiber multiplexing, characterized in that, if the original fiber transmission lines that have been duplicated are both cut off, communication can be continued by transmitting and receiving relay signals between the two optical repeaters. Connection communication method. (2) The optical fiber multiplexing ratio according to claim 1 (claim 11) is characterized in that each optical branching and coupling rate is set so that the received light level at the optical repeater is constant regardless of the originating station. Connection communication system. (3) Patent No. 1 (Covered in the Patent) characterized in that the optical transmission power from each data station is controlled so that the received optical level at the optical repeater is constant regardless of the transmitting station. 1
The optical fiber multiple access communication system according to item 1. (4) During normal operation, the data source station transmits data to the optical fiber with the shorter transmission path via the optical repeater to the destination station.
The optical fiber multiple access communication system according to item 1.