JPH0243831A - Circular optical communication system - Google Patents

Abstract

PURPOSE:To attain optical communication with high transmission efficiency, small transmission delay and high quality by providing an idle slot in response to a transmission capacity from a slave station on an optical transmission line in advance and sending a signal from the slave station to the idle slot. CONSTITUTION:Optical receivers 11, 12 of slave stations 7, 8 receive an optical signal 2 respectively, extract a clock and have the clock with the same frequency as that of a master station 3. In the case of sending an optical signal (a) from a 1st slave station 7, it is communicated in advance with the master station 3 and the master station 3 makes an idle slot 15 in matching with the quantity of information sent from the slave station 7 to a prescribed location of the transmission signal 2. Then the slave station 7 measures the timing from a frame header 113b and sends the optical signal (a) so as to be accommodated in the idle slot 15 and gives it on the optical fiber transmission line 1 via an optical tap 6. Thus, the communication with high transmission efficiency, small propagation delay and excellent quality is implemented.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a ring optical communication system in which a master station and a plurality of slave stations are connected to a ring-shaped end fiber.

(Prior Art) There is a configuration of a circular optical communication system in which a circular optical fiber is provided with an optical tap for connecting a slave station, as shown in FIG. 2. A master station 102 is connected to the circular optical fiber 101, and an optical transmitter 103 . Optical receiver 1
It is connected to 04. Optical taps 105, 106 are installed in the ring-shaped optical fiber μ101, and slave stations 107,
Optical transmitters 109, 110 and optical receiver 111 in 108
, 112. The communication means of the conventional ring optical communication system generally uses the so-called CSMA/CD system. That is, when a slave station attempts to transmit, the optical receivers 111 and 112 first detect whether there is an optical signal on the optical fiber transmission path (CSMA). If there is no optical signal, transmission is performed using optical transmitters 109 and 110.

At this time, the optical receivers 111 and 112 are used to constantly monitor whether the optical signal collides with the signal of another station (CD).
In the event of a collision, transmission is immediately stopped and retransmitted using a predetermined algorithm.

In communication means based on such a system, as the communication traffic of the slave station increases, signal collisions rapidly increase, resulting in a significant drop in transmission efficiency. Moreover, if a collision occurs, a transmission delay occurs, and in principle there is no guarantee of an upper limit to the transmission delay. In addition, because the strength and phase of the optical signal differs depending on which slave station is transmitting and the signal is received by the master station, the slave station sends a preamble, a signal necessary for setting the reception level and phase, before sending the transmission data. There is a need. Therefore, the more the preamble is sent, the more the transmission efficiency is reduced.

Furthermore, in the optical taps 105 and 108, if the transmission signal of the slave station directly enters the receiver of the local station, it will be difficult to detect a collision. This is a complicated configuration using two couplers 121 and 122. Therefore, there are problems in that the loss in the optical taps is large and that the number of optical taps cannot be easily expanded by using an optical repeater in the middle.

There is also a method called polling method as a communication method, but it generally has better transmission efficiency than C3MA/CD method.
This is even more disadvantageous in terms of delay time.

(Problems to be Solved by the Invention) As described above, the conventional ring optical communication system has low transmission efficiency and large transmission delay, and is therefore unsuitable for transmitting audio and images. Moreover, the structure of the optical tap is complicated and requires a large loss, and there are problems in that it is impossible to realize a large system.

Therefore, the present invention was made to eliminate the above-mentioned drawbacks.
High transmission efficiency and low transmission delay.

The object of the present invention is to provide a ring optical communication system that is suitable for transmitting audio, images, etc., has a simple configuration of optical taps, has low loss, and can easily expand the system.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a ring-shaped optical fiber with at least one optical tap, and this optical tap has an optical transceiver. A slave station is connected to the ring-shaped optical fiber, and a master station is connected to the ring-shaped optical fiber without using an optical tap. The slave station detects the frame header, determines its own transmission time from the frame header, and transmits the signal to an empty slot on the optical fiber transmission path with the bit phase matched. The transmission capacity of the slave station is communicated to the master station in advance, and the master station prepares an empty slot in anticipation of the transmission capacity from the slave station.

(Function) In the ring optical communication system of the present invention, an empty slot corresponding to the transmission capacity from the slave station is provided in advance on the optical transmission path -F, and the slave station transmits data to this empty slot. It is possible to perform high-quality optical communication with high transmission efficiency and low transmission delay.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and shows a transmission optical signal 2 on a circular optical fiber 1. As shown in FIG. As shown in FIG. 1, a master station 3 is connected to the optical fiber 1, and an optical transmitter 4 and an optical receiver 5 in the master station 3 are connected.

In addition, a 2×2 directional coupler provided on the optical fiber 1 is used as the 91. The slave stations (7, 8) are connected to the optical tap 6, which is connected to the optical transmitter (9, 10) in each slave station (7, 8).
), which are connected to the optical receivers (11, 12).

It is now assumed that the transmitted optical signal 2 is traveling in the right direction on the optical fiber. In the transmission optical signal 2, 13a, 13b,
13c is a frame header of an optical signal, and each slave station receives the optical signal with its respective optical receiver (11, 12) and detects the frame header. Also 14
indicates information transmitted through the optical fiber 1. Further, each optical receiver (11, 12) extracts a clock from the optical signal and has a clock having the same frequency as that of the master station 3.

When the first slave station 7 transmits the optical signal (a), it contacts the master station 3 in advance, and the master station 3 assigns an empty slot 15 corresponding to the amount of information transmitted by the slave station 7 to the transmission signal 2. Make it in place. Then, the slave station 7 measures the timing from the frame header 113b and sends out the optical signal (a) so that it fits into the empty slot 15. light tap 6
The optical signal (a) that has passed onto the optical fiber propagation path 1 is outputted so that its intensity 9 and phase almost match those of other optical signals.

Adjust the timing based on the signal from the optical receiver. The same procedure is used when the second slave station 8 transmits the optical signal (b).

The intensity 1 phase adjustment of the transmitted optical signal is performed using the optical receiver (11, 12
) to always receive other signals and control the optical transmitters (9, 10). In addition, since a 2x2 directional coupler is used to connect the optical fiber and the slave stations (7, 8), the remaining light that did not get on optical fiber 1 of the optical transmission signal is Since it is guided to the receiver (11° 12), it is easy to monitor the optical signal of the own station with the optical receiver and feed back the amount of deviation to the optical transmitter.

Furthermore, the configuration of the optical tap is simple and the optical loss is small. Therefore, the system can be easily expanded. Moreover, even if the system is expanded and the amount of traffic increases, the transmission efficiency does not decrease, and excellent circular optical communication can be realized.

[Effects of the Invention] As described above, according to the present invention, high-quality communication with high transmission efficiency and small transmission delay can be provided, and high-speed data, audio, video, etc. can be transmitted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a ring optical communication system showing an embodiment of the present invention, FIG. 2 is a 114 block diagram of a conventional ring optical communication system, and FIG.
The figure is a configuration diagram of a slave station using a conventional ring optical communication method. 1... Optical fiber, 3... Master station, 6.
...Optical tap 7.8 ...Slave station, 9.1
0... Optical transmitter 11.12... Optical receiver. 13a, 13b, 13c...Frame header 15...Empty slot Applicant's agent Patent attorney Aide Kensuke Sanno l: Prior fiber 3. Main station 6. Tap ahead 7.
1 + slave station 9, IO + destination transmitter ratio 11 optical receiver 11.13b, Ik + frame header] 5: Empty slot Figure 1

Claims (3)

[Claims] (1) A circular optical fiber is provided with at least one optical tap, a slave station having an optical transceiver is connected to this optical tap, and a master station is connected to the circular optical fiber without going through the optical tap. In the ring optical communication system, the master station is provided with a means for preparing an empty slot corresponding to the transmission capacity from the slave station for a transmission optical signal transmitted through the optical fiber; means for detecting a frame header provided in the transmission optical signal to obtain transmission start timing of the slave station; and means provided in the slave station for adjusting the bit phase to an empty slot of the transmission optical signal in accordance with the timing. A ring optical communication system consisting of a means for transmitting data. (2) The means for transmitting with the bit phases of the slave stations aligned,
Claim (1) characterized in that the optical receiver of the slave station detects the bit frequency and optical intensity from another station, and the optical transmitter of the slave station is controlled based on this data. Ring optical communication system. (3) The optical tap is configured with a directional coupler, and the signal transmitted from the transmitter of the slave station passes through the optical tap, is received by the optical receiver of the slave station, and is compared with other station signals. 2. The ring optical communication system according to claim 1, wherein the optical transmitter at the local station is feedback-controlled so that the bit phase and optical intensity match.