JP3006642B2 - Optical subscriber system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical subscriber system, and more particularly to an optical subscriber system based on a passive double star system.

[0002]

2. Description of the Related Art As shown in FIG. 3, an optical subscriber system based on a passive double star system has a single optical line terminal 20.
A plurality of subscriber units 210 to 212 are connected to one via the star coupler 200.

In some cases, a plurality of station-side devices are provided due to a difference in service contents requested by the subscriber. In this case, as shown in FIG.
4, 315, optical transmission units 306 to 309 having laser diodes of different wavelengths
And the subscriber devices 303 to 305.

In FIG. 3 and FIG. 4, optical transmission lines are provided separately for the upstream and downstream directions. Office device 3
01, 302, each subscriber unit 30
Signals to 3 to 305 are multiplexed, and each subscriber device drops (extracts) a signal addressed to its own station from the multiplexed signal.

The upstream signals from each of the subscriber units 303 to 305 to the optical line terminals 301 and 301 are transmitted as burst signals (optical multiplexed signals), and the transmission timing is adjusted to the optical line units 301 and 302. Control of the burst signal prevents collision of burst signals.

[0006]

However, according to the conventional passive double-star system, when a plurality of optical line units are connected, as shown in FIG. Two or more light receiving units and two or more light transmitting units are required, which makes the system complicated and extremely expensive.

[0007]

In order to solve the above-mentioned problems, the present invention solves the above problem by providing M (natural number) station-side devices, N (natural number) subscriber-side devices, and output from the station-side device. A first M: N star coupler for inputting the multiplexed optical signal and distributing and outputting the multiplexed optical signal to the subscriber unit, and inputting and multiplexing the multiplexed optical signal output from the subscriber unit. An optical subscriber system, comprising at least a second M: N star coupler for distributing and outputting to the optical line terminal, wherein the optical network unit replies to an optical signal from the optical line terminal. Information multiplexing means for multiplexing a plurality of response data signals to be transmitted to at least one optical line terminal and overhead information indicating to which optical line terminal the data is to be transmitted; Signal the second star cap An optical receiver for receiving a response signal distributed and output from the second star coupler, and an overhead for detecting overhead information from the received response signal. It is characterized in that a detecting means and a data extracting means for extracting a data signal addressed to the own station based on the overhead information are provided.

The present invention further provides the optical subscriber system, wherein the optical line transmitting unit generates an optical signal having a wavelength specific to the own station and transmits the optical signal to the first M: N star coupler. Optical signal separating and extracting means for separating and extracting at least one optical signal of at least one wavelength in the multiplexed optical signal output from the first M: N star coupler. And an optical receiving unit for receiving an optical signal having a different wavelength.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. For example, two station-side devices 11, 12 and a plurality of subscriber-side devices 13, 14, 15 are connected to a first and a second star coupler. The passive double star optical subscriber system is constructed by connecting the optical transmission lines 16 and 17 with the three optical transmission lines 32-41.

The optical line terminals 11 and 12 include optical transmitters 18 and 22, optical receivers 19 and 23, signal drop units (signal extraction units) 20 and 24, and overhead detection units (overhead detection units) 21 and 25, respectively. The first and second optical transmitters 18 and 22 include laser diodes having different wavelengths, respectively. In this embodiment, the wavelength signal output from the first optical transmitter 18 is a first wavelength signal, and the wavelength signal output from the second optical transmitter 22 is a second wavelength signal.

First and second star couplers 16 and 17
Have two station-side connections and three subscriber-side connections, respectively, and the first star coupler 16
The second star coupler 17 is used for upstream data transmission.

The subscriber units 13, 14, 15 are:
Wavelength multiplexing / demultiplexing filters (optical signal separation / extraction means) 2
6, a first optical receiving unit 27, a second optical receiving unit 28, an optical transmitting unit 29, a multiplexing unit (signal multiplexing unit) 30, and an overhead signal generating unit 31.

Next, the operation of the optical subscriber system according to this embodiment will be described.

Each of the downlink signals is transmitted to an optical transmission line 32, 36,
The first star coupler 16 is distributed to each of the subscriber units 13 to 15 via the optical transmission lines 34, 38, and 40. The distributed signal is separated into a first wavelength signal and a second wavelength signal by a wavelength division multiplexing / demultiplexing filter 26 in each of the subscriber units 13 to 15. In this embodiment, the first optical receiver 27 receives the first wavelength signal, and the second optical receiver 28 receives the second wavelength signal.

The output signal 103 is a first service output signal, and the output signal 104 is a second service output signal.

On the other hand, the uplink signal is obtained by multiplexing the first service input signal 101 and the second service input signal 102 in the multiplexer 30 of each subscriber unit. At the same time, the signal of the overhead bit generator 31 for generating the overhead bit indicating the insertion position of each of the service input signals 101 and 102 is also multiplexed.

FIG. 2 shows an example of the multiplexed signal. FIG.
In the above, F is a frame signal, OH is an overhead signal, and the overhead signal OH contains overhead information as to whether it is a service input signal to be transmitted to any of the optical line terminals. The multiplexed signal is output from the optical transmitter 29 to the first and second optical network units 11 and 12 as an optical burst signal.

In each of the optical line terminals 11 and 12, this optical burst signal is received by the optical receivers 19 and 23, respectively, and the overhead detectors 21 and 25 detect this. Then, it recognizes the insertion position of the reply data signal and the overhead information for each transmission data signal, and recognizes the signal drop unit 20,
At 24, necessary data signals are dropped (extracted).

For example, the first optical line terminal 11 drops the first data signal shown in FIG. 2, and the second optical line terminal 12 drops the second data signal.

As described above, in the present embodiment, any one of the three subscriber units 13 to 15 transmits two office units 11 and
When two types of signals are multiplexed and transmitted to the transmission unit 12, the overhead signal OH including the insertion position information of each signal is multiplexed together, and each of the optical line terminals 11, 12 detects the overhead signal and outputs a signal addressed to its own station. Is dropped, so that there is no need to control the transmission timing of the multiplexed signal from the subscriber-side device by the station-side device as in the prior art.

When signals are transmitted from the optical line terminals 11 and 12 to each of the optical network units 13 to 15, an optical transmitter for outputting a wavelength signal specific to each optical line terminal is used.
Since these wavelength signals are separated and received by the wavelength division multiplexing / demultiplexing filter 26 of the subscriber side device, it is easy to specify the station side device.

In the present embodiment, two station-side devices and 3
An optical subscriber system of a passive double star system was constructed with two subscriber side devices, but N (natural number) station side devices and M (natural number) subscriber side devices were connected to two M: N star couplers. It is also possible to adopt a configuration in which connection is made via

[0024]

As described above, according to the present invention, when multiplexing and transmitting a data signal from a subscriber unit to a plurality of central units, the overhead information indicating the signal insertion position is added and the station information is added. The side device recognizes the signal insertion position based on this overhead information and drops the signal addressed to its own station, so the number of components can be reduced compared to the conventional system, and the system can be constructed at low cost. Can be.

When transmitting a signal from the optical line terminal to each subscriber side device, an optical transmitter for outputting a wavelength signal unique to each optical line side device is used, and these wavelength signals are separated by the subscriber side device. Since the reception is performed after the reception, it is easy to specify the optical line terminal.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical subscriber system according to one embodiment of the present invention.

FIG. 2 is a data structure diagram of signal burst data according to the present embodiment.

FIG. 3 is a block diagram of a conventional optical subscriber system.

FIG. 4 is another block diagram of a conventional optical subscriber system.

[Explanation of symbols]

11, 12, 201, 301, 302 Station-side device 13, 14, 15, 202-204, 303-305
Subscriber-side devices 16, 17 Star couplers 18, 22, 205-208, 306-309 Optical transmitters 19, 23, 27, 28, 209-212, 310-3
DESCRIPTION OF SYMBOLS 13 Optical receiving part 20, 24 Signal drop part 21, 25 Overhead detecting part 26, 314, 315 Wavelength multiplexing / demultiplexing filter 30 Multiplexing part 31 Overhead signal generating part 32-41 Optical transmission path 101-108 Service signal

Claims (3)

(57) [Claims] 1. M (natural number) optical network units, N (natural number) optical network units, and a multiplexed optical signal output from the optical network unit, which are input to the subscriber side. A first M: N star coupler for distributing and outputting to a device, and a second M: N star coupler for receiving a multiplexed optical signal output from the subscriber side device and distributing and outputting the multiplexed optical signal to the station side device. An optical subscriber system having a configuration in which the subscriber unit replies to an optical signal from the optical line terminal, a plurality of replies sent to the optical line unit to at least one optical line unit. Information multiplexing means for multiplexing a data signal and overhead information indicating to which station side equipment the data signal is to be returned, and reply signal transmitting means for transmitting the multiplexed signal to the second star coupler The station-side device An optical receiver for receiving a response signal distributed and output from the second star coupler, overhead detecting means for detecting overhead information from the received response signal, and data addressed to the own station based on the overhead information. An optical subscriber system, comprising: data extraction means for extracting a signal. 2. The optical subscriber system according to claim 1, wherein said overhead information is data insertion position information at the time of multiplexing. 3. The optical subscriber system according to claim 1, further comprising: generating an optical signal having a wavelength specific to the local station in the optical line terminal, and generating the first M: N star signal. An optical transmitter for transmitting an optical signal to at least one wavelength in the multiplexed optical signal output from the first M: N star coupler; An optical subscriber system comprising: a separating / extracting unit; and an optical receiving unit that receives an optical signal having an extracted wavelength.