WO2009122577A1

WO2009122577A1 - Optical communication system, master station, and slave station

Info

Publication number: WO2009122577A1
Application number: PCT/JP2008/056596
Authority: WO
Inventors: 聡吉間; 巨生鈴木
Original assignee: 三菱電機株式会社
Priority date: 2008-04-02
Filing date: 2008-04-02
Publication date: 2009-10-08

Abstract

An optical communication system comprises a single master station (10), a plurality of slave stations (30) housed in the master station (10), and a remote node (20) which divides a wavelength division multiplex transmitted optical signal from the master station to each slave station and combines optical signals transmitted from each slave station to the master station, using the AWG. The master station (10) generates, for each slave station (30), a plurality of optical signals having different wavelengths determined in advance based on the FSR of the AWG which are to be transmitted toward one and the same slave station (30), as downstream signals to be transmitted to each slave station (30).

Description

Optical communication system, master station device and slave station device

The present invention relates to an optical communication system for simultaneously transmitting optical signals of a plurality of wavelengths by wavelength division multiplexing.

There is a wavelength division multiplexing passive optical network as one of optical networks for realizing optical communication. In this wavelength division multiplexing passive optical network, one master station device (OLT: Optical Line Terminal) and a plurality of slave station devices (ONU: Optical Network Unit) are connected via an optical fiber transmission line, an optical power splitter, etc. This is a system that performs bidirectional communication so that the wavelength band of the downlink signal transmitted from the master station device to each slave station device and the uplink signal transmitted from each slave station device to the master station device do not overlap (for example, the following patent document) 1).

Further, in the following Non-Patent Document 1, in a wavelength division multiplexing passive optical network, in order to realize single-core bidirectional communication, an arrayed waveguide grating is connected to a remote node installed between a master station device and each slave station device. Using AWG (Arrayed Waveguide Grating), a method has been proposed in which light of two wavelengths separated by the wavelength period (FSR: Free Spectral Range) of this arrayed waveguide grating is allocated for transmission of downstream and upstream signals. Yes.

In this way, in the wavelength division multiplexing passive optical network, the wavelength (band) of the uplink signal and the downlink signal is exclusively assigned to each slave station device, and therefore, the bandwidth is time-divided into a plurality of slave station devices. Unlike passive optical networks that use the assigned TDMA (Time Division Multiple Access) method, the bandwidth of upstream and downstream signals is not limited even when the number of users increases.

JP 2006-197489 A

In the wavelength division multiplexing passive optical network described in Non-Patent Document 1, an arrayed waveguide grating is used as a remote node, and a smaller number of slave station devices than the number of output ports of the arrayed waveguide grating and one parent station device are used. Perform bidirectional communication. However, in this method, only one wavelength can be assigned to each slave station device for transmission of the downlink signal, so when a plurality of different types of downlink signals are transmitted simultaneously, the bandwidth allocated to each signal is limited. There was a problem of being.

For example, when downlink signals with different modulation methods and bands such as data communication, voice communication, and video distribution are transmitted in the same wavelength band, crosstalk is likely to occur between the signals, and band limitation is imposed on each signal. . In particular, data communication is performed in response to a downlink signal request, whereas video distribution has a large amount of data and has a smaller allowable delay time than data communication. For this reason, it is desirable to always secure a band for video distribution as the band of the downstream signal. For reference, in the optical access network adopting the TDMA system, the 1550 nm band is defined in the standardization standard (IEEE 802.3-2005) as a band for video distribution.

The present invention has been made in view of the above, and an optical communication system capable of simultaneously transmitting downlink signals of two or more wavelengths from a master station apparatus to one slave station apparatus by applying a wavelength division multiplexing system, An object is to obtain a master station device and a slave station device constituting the same.

In order to solve the above-described problems and achieve the object, an optical communication system according to the present invention uses a single master station device, a plurality of slave station devices accommodated in the master station device, and an AWG. A remote node that demultiplexes the optical signal transmitted from the master station device to each of the slave station devices and multiplexes the optical signal transmitted from each of the slave station devices to the master station device. The master station device has a wavelength determined in advance based on the FSR of the AWG as a downlink signal to be transmitted to each of the slave station devices, and different wavelengths transmitted to the same slave station device. The plurality of optical signals are generated for each slave station device.

The optical communication system according to the present invention uses an arrayed waveguide grating (AWC) as a remote node, and the master station device transmits a plurality of optical signals at wavelengths considering the wavelength period of the arrayed waveguide grating to each slave station device. Since the signal is transmitted, even if the number of users (slave station devices) increases, both the upstream and downstream signals are not subject to bandwidth limitations, and a wider bandwidth is available compared to the prior art. There exists an effect that it can allocate with respect to a station apparatus.

In addition, since only the downstream signal that should be received by the connected slave station device flows through the transmission path between each slave station device and the remote node, each slave station device has a wavelength that it should receive. There is no need to provide a wavelength selection filter for extracting only the first signal, and the cost of the slave station apparatus can be reduced.

FIG. 1 is a diagram illustrating a configuration example of the optical communication system according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of a transmission processing unit included in the master station device. FIG. 3 is a diagram illustrating a configuration example of a reception processing unit included in the master station device. FIG. 4 is a diagram illustrating an example of a wavelength arrangement of an optical signal used in the optical communication system according to the first embodiment. FIG. 5 is a diagram illustrating a configuration example of the optical communication system according to the second embodiment.

Explanation of symbols

10 Master station equipment (OLT)
11, 31 Transmission processing unit (Tx)
12, 32-1, 32-2 Reception processing unit (Rx)
13, 33 Multiplexing / demultiplexing unit 20 Remote node (RN)
21 Arrayed waveguide grating (AWG)
30, 30a Slave unit (ONU)
34, 122 Demultiplexing unit 35 Optical power splitter 36-1, 36-2 Band pass filter 111 ₁ to 111 _2n Optical signal generation unit 112 Multiplexing unit 121 ₁ to 121 _n Optical detection unit

Hereinafter, embodiments of an optical communication system according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of an optical communication system according to the present invention. This optical communication system is composed of a master station device (OLT) 10, a remote node (RN) 20, and a plurality of slave station devices (ONU) 30 accommodated in the master station device 10, and the master station device 10 and each slave device. Each of the station devices 30 is connected to the remote node 20 via a single optical fiber. Each slave station device 30 has the same configuration. Further, in the following description, when a specific slave station device is described, the slave station devices # 1, # 2,.

As shown in FIG. 1, the master station device 10 includes a transmission processing unit (Tx) 11, a reception processing unit (Rx) 12, and a multiplexing / demultiplexing unit 13.

The transmission processing unit 11 modulates a plurality of lights having different wavelengths allocated for downlink data transmission with different electrical signals, and generates a plurality of downlink optical signals. The reception processing unit 12 demultiplexes a plurality of wavelength-division multiplexed upstream optical signals that are input signals, and demodulates the separated optical signals as different electrical signals. The multiplexing / demultiplexing unit 13 separates the downstream optical signal and the upstream optical signal. The multiplexing / demultiplexing unit 13 can be realized by using, for example, a wavelength division multiplexing (WDM) filter.

The remote node 20 is composed of an arrayed waveguide grating (AWG) 21. When the arrayed waveguide grating 21 receives the optical signal transmitted from the master station apparatus 10 by wavelength division multiplexing, each optical signal is demultiplexed. Are output (demultiplexed) to the corresponding slave station device 30. When receiving optical signals from each slave station device 30, they are multiplexed (combined) and output to the master station device 10.

The slave station device 30 includes a transmission processing unit (Tx) 31, reception processing units (Rx) 32-1 and 32-2, a multiplexing / demultiplexing unit 33, and a demultiplexing unit 34.

The transmission processing unit 31 (upstream signal generating means) converts the input upstream electrical signal into an upstream optical signal having a wavelength assigned in advance. The reception processing units 32-1 and 32-2 (reception processing means) individually execute predetermined reception processing on each downstream optical signal output from the demultiplexing unit 34, and convert it into a downstream electrical signal. The multiplexing / demultiplexing unit 33 separates the downlink signal and the uplink signal. The downlink signal obtained by executing this separation process is a signal in which a plurality of downlink optical signals are multiplexed. The demultiplexing unit 34 performs demultiplexing processing on the downlink signal received from the multiplexing / demultiplexing unit 33, and each of the obtained downlink optical signals corresponds to a corresponding reception processing unit (reception processing unit 32-1 or 32). -2). In the present embodiment, the demultiplexing unit 34 is realized using a WDM filter.

FIG. 2 is a diagram illustrating a configuration example of the transmission processing unit 11 included in the master station device 10. This transmission processing unit 11 includes optical signal generation units 111 ₁ to 111 _2n (optical signal generation unit) and multiplexing unit 112 (multiplexing unit) corresponding to the number of downlink channels that can be used in the system (2n in the present embodiment). Each optical signal generation unit generates light having a wavelength of λ ₁ to λ _2n and modulates the generated light with the input downstream electrical signal to generate a plurality of downstream optical signals having different wavelengths. To do. The multiplexer 112 multiplexes (combines) the downlink optical signals generated by the optical signal generators and outputs the multiplexed signals as downlink signals.

FIG. 3 is a diagram illustrating a configuration example of the reception processing unit 12 included in the master station device 10. This reception processing unit 12 includes photodetectors 121 ₁ to 121 _n and demultiplexing units 122 corresponding to the number of uplink channels that can be used in the system (n in the present embodiment), and each of the photodetecting units includes demultiplexing units. The upstream optical signal received from 122 is converted into an upstream electrical signal. The demultiplexing unit 122 receives an uplink signal, which is a signal obtained by multiplexing the uplink optical signal, from the multiplexing / demultiplexing unit 13, demultiplexes, and outputs each uplink optical signal to the corresponding photodetector.

Here, the wavelength of each optical signal handled in the optical communication system of the present embodiment will be described. FIG. 4 is a diagram illustrating an example of the wavelength arrangement of an optical signal used in the optical communication system according to the present embodiment. Specifically, one upstream optical signal is transmitted to each slave station device 30 in the downstream direction. An example in which two optical signals are allocated is shown.

When the wavelength interval at each port of the arrayed waveguide grating 21 shown in FIG. 1 is Δλ and the wavelength period (FSR: Free Spectral Range) is n × Δλ, in this embodiment, the wavelength λ is the wavelength for the downstream signal. the 2n-number of wavelengths from ₁ up to a wavelength lambda _2n (light), assigning the n-number of wavelengths from the wavelength lambda _{2n + 1} as a wavelength for an upstream signal to the wavelength lambda _3n (light). It is assumed that the wavelength λ ₁ is located on the shortest wavelength side. This utilizes the characteristics of the arrayed waveguide grating, and utilizes the fact that signals having wavelengths separated by an integral multiple of the FSR are output from the same port.

In the optical communication system according to the present embodiment to which the above-described wavelength arrangement is applied, when performing triple play, for example, a data signal and an audio signal for each slave station apparatus are allocated from wavelength λ ₁ to wavelength λ _n , and wavelength λ Video signals for each slave station device are assigned from _{n + 1} to wavelength λ _2n . Thereby, it is possible to realize a system in which a band for video distribution is always ensured and a band for video signals is not limited. In the example shown in FIG. 4, a data signal and an audio signal are transmitted from the remote node 20 to the slave station (ONU) # 1 using light having a wavelength of λ ₁ , and the wavelength is λ _{n + 1.} The video signal is transmitted using the light of the light. At this time, the upstream signal from the slave station apparatus # 1 is transmitted using light having a wavelength of λ _{2n + 1} .

Note that the number of wavelengths of the downlink signal (light) assigned to each slave station device is not limited to two wavelengths, and if the wavelength band of the arrayed waveguide grating 21 permits, the number of wavelengths is three or more (array guides for a certain wavelength). A plurality of light beams having wavelengths separated by an integral multiple of the FSR of the waveguide grating 21 may be assigned. Further, the wavelength arrangement is not limited to that shown in FIG. For example, the wavelength arrangement of the downlink signal and the uplink signal may be switched so that the uplink signal is arranged on the short wavelength side and the downlink signal is arranged on the long wavelength side.

Next, an operation when the master station device 10 transmits a downlink signal to each slave station device 30 in the optical communication system having the above configuration will be described with reference to FIGS.

When a plurality of downlink data (downlink electrical signals) to each slave station device 30 is input to the transmission processing unit 11 (see FIG. 2) of the master station device 10, each downlink electrical signal is input to the corresponding optical signal generation unit. Then, each optical signal generation unit generates a downstream optical signal having a wavelength assigned to itself based on the input downstream electrical signal. Incidentally, as shown in FIG. 4, for the slave station apparatus # 1, the wavelength _λ1 and this and FSR only wavelengths distant lambda _{n + 1} of the downstream optical signal is an optical signal generating unit 111 ₁ and 111 n ₊ Generated in ₁ . Similarly, for the slave station device #n, the

optical signal generators

111 _n and 111 _2n generate the downstream optical signal having the wavelength λ _n and the wavelength λ _2n that is separated from the wavelength λ _{n by the} FSR. The multiplexing unit 112 receives downstream optical signals generated in each optical signal generation unit, wavelength-division multiplexes them, and generates a signal (downstream signal) in which each downstream optical signal is multiplexed.

The downlink signal generated by the transmission processing unit 11 is transmitted to the remote node 20 via the multiplexing / demultiplexing unit 13, and the arrayed waveguide grating 21 of the remote node 20 demultiplexes the input downlink signal and outputs each downlink signal. The optical signal is output to a port (optical fiber) to which the corresponding slave station device 30 is connected. Specifically, as shown in FIG. 4, and outputs the downstream signal wavelength lambda _{n + 1} at a distance downstream signal and this and FSR fraction of the wavelength lambda ₁ from port connected to the slave station apparatuses # 1 . Similarly, downstream signals of wavelengths λ ₂ and λ _{n + 2} are transmitted from the port connected to slave station apparatus # 2, and downstream signals of wavelengths λ _n and λ _2n are transmitted from the port connected to slave station apparatus #n. ,Output.

In each slave station device 30, the signal received from the remote node 20 is first passed to the multiplexing / demultiplexing unit 33, and the multiplexing / demultiplexing unit 33 extracts the downlink signal and outputs it to the demultiplexing unit 34. The demultiplexing unit 34 distributes a plurality of (two in the present embodiment) downstream optical signals that are signals received from the multiplexing / demultiplexing unit 33 to the corresponding reception processing units 32-1 or 32-2. . Each reception processing unit executes predetermined reception processing including processing for converting the received downstream optical signal into an electrical signal.

The operation when each slave station device 30 transmits uplink data to the master station device 10 will be described. The transmission processing unit 31 of each slave station device 30 receives an upstream optical signal having a wavelength separated by FSR (= n × Δλ) from the longest wavelength among the plurality of downstream optical signals allocated to the local station device. It is generated and transmitted to the remote node 20 via the multiplexing / demultiplexing unit 33. For example, in the slave station device # 1, the transmission processing unit 31 generates an upstream optical signal with a wavelength λ _{2n + 1 that} is separated from the downstream optical signal with λ _{n + 1} by FSR. Similarly, the slave station device # 2 generates an upstream optical signal of λ _{2n + 2} , and the slave station device #n generates an upstream optical signal of λ _3n .

In the remote node 20, the upstream optical signal received from each slave station device 30 is input to the arrayed waveguide grating 21. As described above, each upstream optical signal has a wavelength separated from the downstream optical signal by FSR, and therefore each upstream optical signal is output to a port (optical fiber) to which the master station device 10 is connected. As a result, a signal obtained by multiplexing a plurality of upstream optical signals is output to the master station device 10.

In the master station device 10, when an upstream signal in which a plurality of upstream optical signals are multiplexed is received from the remote node 20, the upstream signal is passed to the reception processing unit 12 via the multiplexing / demultiplexing unit 13, and the reception processing unit 12. In (see FIG. 3), first, the demultiplexing unit 122 demultiplexes and distributes each upstream optical signal to the corresponding optical detection unit. Each optical detection unit converts the received upstream optical signal into an upstream electrical signal and outputs it.

As described above, the optical communication system according to the present embodiment includes a remote node that performs demultiplexing and multiplexing of an optical signal using an arrayed waveguide grating between a master station device and a plurality of slave station devices. The master station device transmits downlink data to the slave station device using light having a certain wavelength and light having a wavelength separated from this light by an integral multiple of the wavelength period (FSR) of the arrayed waveguide grating. did. Thereby, two or more downstream signals can be simultaneously transmitted to one slave station device. Further, since only the downstream optical signal to be received by the connected slave station device is output to the transmission path (optical fiber) between the remote node and each slave station device, each slave station device A wavelength selection filter for extracting the downstream optical signal is not necessary, and the cost of the slave station apparatus can be reduced.

In the above description, the case where the downlink signal is two waves has been described. However, when the number of wavelengths of the downlink signal is three or more, the demultiplexing unit 34 of the slave station device 30 is set according to the number of wavelengths. The WDM filter used in the system is expanded, and the downlink signal wavelengths are cut out in order from the long wavelength side or the short wavelength side, so that all the multiplexed downlink signal wavelengths are received by different reception processing units (reception processing units corresponding to the respective wavelengths). ).

Embodiment 2. FIG.
Next, the optical communication system according to the second embodiment will be described. In the first embodiment described above, the configuration in the case where the demultiplexing unit 34 of the slave station device 30 is realized by a WDM filter has been described. However, the configuration can be realized without using a WDM filter. Therefore, in the present embodiment, an example in the case where the WDM filter is not used will be described.

FIG. 5 is a diagram illustrating a configuration example of the optical communication system according to the second embodiment. In the optical communication system according to the present embodiment, the configurations of the master station device and the remote node are the same as those of the optical communication system according to the first embodiment described above, but only the configuration of the slave station device is different. Therefore, in the present embodiment, only the slave station device 30a that is different from the first embodiment will be described. In addition, the same code | symbol is attached | subjected about the same part as the subunit | mobile_unit apparatus 30 shown in Embodiment 1, and description is abbreviate | omitted.

As shown in FIG. 5, the slave station device 30a includes a transmission processing unit 31, reception processing units 32-1 and 32-2, which have a common configuration with the slave station device 30 shown in the first embodiment. In addition to the demultiplexing unit 33, an optical power splitter 35 and bandpass filters 36-1 and 36-2 are provided.

When the optical power splitter 35 receives an optical signal in which a plurality of downstream optical signals are multiplexed from the multiplexing / demultiplexing unit 33, the optical power splitter 35 distributes them to the corresponding bandpass filter 36-1 or 36-2.

For the bandpass filters 36-1 and 36-2, the wavelength of the optical signal to be transmitted is set in advance. For example, if the bandpass filters 36-1 and 36-2 are included in the slave station device # 1, the wavelength lambda ₁ signal to the reception processing section 32-1, distributes as wavelength lambda _{n + 1} signal is supplied to a reception processing section 32-2.

In order to expand the expandability of the system, variable bandpass filters that can change the transmission wavelength band may be used as the bandpass filters 36-1 and 36-2. Further, when the number of wavelengths of the downlink signal is three or more, an optical power splitter that can divide the signal by the number of downlink signals in the slave station device 30a according to the number of wavelengths, and an downlink optical signal of a specific wavelength As a configuration including a plurality of band-pass filters that pass only the light, all multiplexed downlink signal wavelengths are distributed to different reception processing units (reception processing units corresponding to the respective wavelengths).

Thus, in this embodiment, the optical power splitter and the plurality of bandpass filters are used as a configuration for distributing a plurality of downstream optical signals to the reception processing unit in the slave station apparatus. Thereby, the same effect as the optical communication system shown in Embodiment 1 can be acquired.

As described above, the optical communication system according to the present invention is useful for an optical communication system to which the wavelength division multiplexing system is applied, and in particular, can transmit optical signals having a plurality of wavelengths simultaneously to one slave station device. Suitable for realizing the system.

Claims

A single master station device,
A plurality of slave station devices accommodated in the master station device;
Remote using AWG to demultiplex an optical signal wavelength-division-multiplexed and transmitted from the master station device to the slave station devices and to combine optical signals transmitted from the slave station devices to the master station device Nodes,
With
The master station device has a wavelength determined in advance based on the FSR of the AWG as a downlink signal to be transmitted to each slave station device, and a plurality of different wavelengths transmitted to the same slave station device. An optical communication system, wherein the optical signal is generated for each slave station device.
2. The optical communication system according to claim 1, wherein a plurality of optical signals having different wavelengths transmitted toward the same slave station device are a plurality of optical signals having wavelengths separated by an integral multiple of the FSR. .
The slave station device has an optical signal having the longest wavelength or an optical signal having the shortest wavelength among a plurality of optical signals transmitted from the master station device to the own device as an upstream signal to be transmitted to the master station device. The optical communication system according to claim 1, wherein an optical signal having a wavelength determined in advance based on the reference signal and the FSR is generated.
The slave station device, when the reference signal is the optical signal having the longest wavelength, generates an optical signal having a wavelength separated from the optical signal having the longest wavelength by the FSR to the long wavelength side as the upstream signal, Further, when the reference signal is the optical signal having the shortest wavelength, an optical signal having a wavelength separated from the optical signal having the shortest wavelength by the FSR to the short wavelength side is generated as the upstream signal. The optical communication system according to claim 3.
Remote using a plurality of slave station apparatuses and demultiplexing optical signals transmitted by wavelength division multiplexing toward the plurality of slave station apparatuses and combining optical signals transmitted from the respective slave station apparatuses. A master station device that constitutes an optical communication system together with a node,
An optical signal generating means for generating, for each of the slave station devices, a plurality of optical signals having wavelengths that are determined in advance based on the FSR of the AWG and transmitted to the same slave station device; ,
Multiplexing means for multiplexing each optical signal generated by the optical signal generating means;
A master station device comprising:
6. The master station apparatus according to claim 5, wherein a plurality of optical signals having different wavelengths transmitted to the same slave station apparatus are a plurality of optical signals having wavelengths separated by an integral multiple of the FSR. .
A master station device, and a remote node that uses AWG to demultiplex an optical signal transmitted from the master station device by wavelength division multiplexing and multiplex an optical signal transmitted to the master station device. A slave station device constituting an optical communication system,
The optical signal having the longest wavelength or the optical signal having the shortest wavelength among a plurality of optical signals that are signals transmitted from the master station device through wavelength division multiplexing and received via the remote node is used as a reference signal, and the reference signal and Uplink signal generation means for generating an optical signal having a wavelength determined in advance based on the FSR of the AWG as an uplink signal to be transmitted to the master station device,
A slave station device comprising:
When the reference signal is the optical signal having the longest wavelength, the upstream signal generating means generates an optical signal having a wavelength separated from the optical signal having the longest wavelength by the FSR to the long wavelength side as the upstream signal. Further, when the reference signal is the optical signal having the shortest wavelength, an optical signal having a wavelength separated from the optical signal having the shortest wavelength by the FSR to the short wavelength side is generated as the upstream signal. The slave station apparatus according to claim 7.
further,
Demultiplexing means for performing demultiplexing processing using a wavelength division multiplexing filter on a plurality of optical signals having different wavelengths, which are signals that are wavelength division multiplexed transmitted from the master station device and received via the remote node; ,
Receiving processing means for individually executing a predetermined receiving process on each optical signal after being demultiplexed by the demultiplexing means;
The slave station apparatus according to claim 7 or 8, further comprising:
further,
A demultiplexing process using an optical power splitter and a plurality of bandpass filters for a plurality of optical signals having different wavelengths, which are signals transmitted from the master station device and received via the remote node. Wave means,
Receiving processing means for individually executing a predetermined receiving process on each optical signal after being demultiplexed by the demultiplexing means;
The slave station apparatus according to claim 7 or 8, further comprising: