JP2008092194A - Light wavelength assignment method and optical communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress effectively deterioration of line quality caused by the transmission loss in each receiving side device, with the respect to a light wavelength assignment method and an optical communications system. <P>SOLUTION: In the light wavelength assignment method for assigning received wave length of two or more reception side devices in an optical communications system using a wavelength division multiplex transmission method, the longest wavelength is transmitted to each reception side device from a transmitting side device among wavelengths of light used by communications between a transmitting side device and each reception side device. The transmission loss of the longest wavelength is measured in each reception side device, and the result is notified to the transmitting side device. Based on the notice of the transmission loss from each reception side device, the transmitting side device is constituted so as to assign a wavelength in order from a receiving side device of the largest transmission loss and from the longest received wave length. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical wavelength allocation method and an optical communication system, and in particular, an optical wavelength allocation method for allocating a reception wavelength to a receiving apparatus when performing optical communication using a wavelength division multiplexing transmission system, and such an optical wavelength allocation method. TECHNICAL FIELD

  When performing optical communication using an optical transmission line composed of an optical fiber, the transmission capacity cannot be increased at that rate simply because the transmission frequency is high. Therefore, by using a wavelength division multiplexing (WDM) transmission method, for example, light between a transmission side device such as an OSU (Optical Subscriber Unit) and a reception side device such as a plurality of ONUs (Optical Network Unit). The transmission path can be used effectively. In this case, for each ONU, for example, a reception wavelength is fixedly assigned according to the ID of each ONU. When information is transmitted from the OSU to a plurality of ONUs via the optical coupler, each ONU captures information on the reception wavelength assigned to each ONU.

The optical demultiplexer only has to demultiplex only the downstream signal by synthesizing the upstream optical signal from each slave station to the master station by the optical coupler and sending it to the master station through the optical path separator. A wavelength multiplexing PON (Passive Optical Network) system that minimizes the number is proposed in Patent Document 1, for example.
Japanese Patent Laying-Open No. 2005-12278

  Conventionally, when information is transmitted from an OSU to each ONU via an optical coupler, the distance of the optical fiber from the optical coupler to each ONU is different, so even if the characteristics of each ONU itself are substantially the same, due to transmission loss The degradation of the line quality differs for each ONU. Also, due to the characteristics of the optical fiber, the attenuation of the transmission waveform tends to increase as the transmission wavelength is shorter. Even if the distance of the optical fiber from the optical coupler to the ONU is the same, the ONU line to which a shorter reception wavelength is assigned. The deterioration in quality is greater than the deterioration in line quality of an ONU to which a longer reception wavelength is assigned. For this reason, there is a problem that it is difficult to suppress deterioration of the line quality due to transmission loss in each ONU.

  Therefore, an object of the present invention is to provide an optical wavelength allocation method and an optical communication system that can effectively suppress degradation of channel quality due to transmission loss in each receiving-side apparatus.

  The above problem is an optical wavelength allocation method for allocating reception wavelengths of a plurality of reception side devices in an optical communication system using a wavelength division multiplexing transmission system, and is used in communication between a transmission side device and each reception side device. Measuring the longest wavelength among the wavelengths of light transmitted from the transmitting device to each receiving device, measuring the transmission loss of the longest wavelength in each receiving device, and measuring from each receiving device. Informing the transmission side device of the transmission loss, and in the transmission side device, assigning from the longest reception wavelength in order from the reception side device with the largest transmission loss based on the transmission loss notification from each reception side device The method can be achieved by an optical wavelength assignment method characterized in that

  An object of the present invention is an optical communication system using a wavelength division multiplex transmission system, comprising: a transmission side device; and a plurality of reception side devices capable of communicating with the transmission side device via an optical transmission line. The apparatus includes transmission means for transmitting the longest wavelength of light used in communication with each receiving apparatus to each receiving apparatus, and each receiving apparatus transmits a transmission loss of the longest wavelength. Measuring means for measuring the transmission loss, and a notification means for notifying the transmission side device of the measured transmission loss, the transmission side device is based on the transmission loss notification from each reception side device, the largest transmission loss of This can be achieved by an optical communication system characterized by further comprising wavelength allocation means for allocating from the longest reception wavelength in order from the reception side device.

  ADVANTAGE OF THE INVENTION According to this invention, the optical wavelength allocation method and optical communication system which can suppress effectively deterioration of the channel quality by the transmission loss in each receiving side apparatus are realizable.

  An optical fiber used for optical communication has a characteristic that the longer the transmission wavelength, the less the attenuation even if the transmission distance is longer. Therefore, the present invention makes effective use of the characteristics of this optical fiber.

  Specifically, the longest wavelength among the wavelengths of light used between the transmission side device and the plurality of reception side devices is transmitted from the transmission side device to each reception side device. Each receiving side device calculates the transmission loss of the received wavelength and notifies the transmitting side device. Based on the notification from each receiving side device, the transmitting side device assigns from the longest receiving wavelength in order from the receiving side device with the largest transmission loss. That is, a long reception wavelength is assigned to a reception-side device with a large transmission loss, and a short reception wavelength is assigned to a reception-side device with a small transmission loss.

  As a result, it is possible to effectively suppress deterioration of the line quality due to transmission loss in each receiving-side apparatus. Also, by performing the reassignment of the reception wavelength according to the increase / decrease of the receiving side device, the line quality can be optimized regardless of the increase / decrease of the receiving side device.

  Embodiments of an optical wavelength assignment method and an optical communication system according to the present invention will be described below with reference to the drawings.

  1 and 2 are block diagrams for explaining the operation of an embodiment of the optical communication system of the present invention. This embodiment of the optical communication system uses an embodiment of the optical wavelength assignment method of the present invention. In this embodiment, for convenience of explanation, it is assumed that the present invention is applied to a WDM-PON system.

  As shown in FIGS. 1 and 2, the WDM-PON system 1 includes an OSU 2 that constitutes a transmission-side device, an optical coupler 3, and a plurality of ONUs 4-1 to 4-n that constitute a reception-side device. Here, n is an integer of 2 or more. The OSU 2 and the optical coupler 3 are connected by an optical fiber cable 11, and the optical coupler 3 and the ONUs 4-1 to 4-n are connected by corresponding optical fiber cables 12-1 to 12-n. The lengths of the optical fiber cables 12-1 to 12-n differ depending on the physical arrangement of the ONUs 4-1 to 4-n and are not all the same length. Further, the number of wires (or the number of optical fibers) of each of the optical fiber cables 11, 12-1 to 12-n can be arbitrarily set according to the type of information to be transmitted.

  For example, if the transmission speed of the optical transmission line between the OSU 2 and the ONUs 4-1 to 4-n is 1 Gbps and n = 32, each ONU 4-1 to 4-32 can obtain a transmission speed of 30 Mbps or more. .

  First, as shown in FIG. 1, the longest wavelength λ1 among the wavelengths of light used in communication between the OSU 2 and each of the ONUs 4-1 to 4-n is changed from the OSU 2 through the optical coupler 3 to each ONU 4- 1 to 4-n.

  Also, as shown in FIG. 1, the ONUs 4-1 to 4-n obtain the transmission losses 11 to ln of the received wavelength λ1 and notify the OSU 2 of them. Here, for convenience of explanation, it is assumed that the transmission losses l1 to ln satisfy the relationship of l1> l2>. For convenience of explanation, FIG. 1 shows a case where the ONUs 4-1 to 4-n are arranged in the order of the subscript numbers, but the relative positional relationship of the ONUs 4-1 to 4-n is that shown in FIG. Needless to say, it is not limited to.

  Based on the notification of the transmission losses 11 to ln from the ONUs 4-1 to 4-n, the OSU 2 assigns from the longest reception wavelength λ1 in order from the ONU 4-1 having the largest transmission loss 11 as shown in FIG. That is, a long reception wavelength is assigned to an ONU having a large transmission loss, and a short reception wavelength is assigned to an ONU having a small transmission loss. As a result, the reception wavelengths λ1 to λn are assigned to the ONUs 4-1 to 4-n, respectively. The reception wavelengths λ1 to λn satisfy the relationship of λ1> λ2>.

  As a result, it is possible to effectively suppress deterioration in line quality due to transmission loss in each of the ONUs 4-1 to 4-n. Also, by reassigning the received wavelength according to the increase / decrease of the ONU, the line quality can be optimized regardless of the increase / decrease of the ONU.

  If there are two or more ONUs having the same transmission loss, the received wavelengths can be assigned to the ONUs having the same transmission loss in any order. For example, the arbitrary order may be determined in advance or may be determined according to the ID of each ONU.

  FIG. 3 is a timing chart for explaining the operation of this embodiment. As shown in FIG. 3, when the OSU 2 transmits the wavelength λ1 to each of the ONUs 4-1 to 4-n, the ONUs 4-1 to 4-n determine the transmission losses l1 to ln of the received wavelength λ1 and notify the OSU2.

  FIG. 4 is a diagram for explaining transmission loss measurement processing (or transmission loss calculation processing) of each ONU 4-1 to 4-n. In FIG. 4, step ST1 converts the reception level of the light of wavelength λ1 received from OSU2 into a corresponding voltage level by the optical / electrical converter. In step ST2, the voltage level obtained from the optical / electrical converter is converted into a corresponding digital value by an analog / digital (A / D) converter. In step ST3, the transmission loss calculation unit calculates the transmission loss by comparing the digital value obtained from the A / D conversion unit with a known reference value. This reference value is a digital value obtained when the optical output level of the OSU 2 known in advance is passed through the optical / electrical converter and the A / D converter. Note that the transmission loss measurement processing of each ONU 4-1 to 4-n is not limited to the one shown in FIG. 4, and can be measured by any method. For example, when the ONU has an automatic gain control unit including an amplification unit that amplifies the reception level of received light to a predetermined level, an increase from the ideal value of the gain of the amplification unit controlled by the automatic gain control unit The transmission loss can also be measured (or calculated) based on the above.

  Returning to the description of FIG. 3, the OSU 2 gives an instruction to receive the longest reception wavelength λ1 to the ONU 4-1 having the largest transmission loss 11 based on the notification of the transmission losses 11 to 1 -n from the ONUs 4-1 to 4 -n. When the reception response to the transmission and reception instruction returns from the ONU 4-1, the allocation of the longest reception wavelength λ 1 to the ONU 4-1 is completed. Similarly, when a reception instruction of the shortest reception wavelength λn is sent to the ONU 4-n having the smallest transmission loss ln and a reception response to the reception instruction returns from the ONU 4-n, this shortest reception wavelength for the ONU 4-n The assignment of λn ends. In this way, a long reception wavelength is assigned to an ONU with a large transmission loss, a short reception wavelength is assigned to an ONU with a small transmission loss, and as a result, the reception wavelengths λ1 to λ1 are assigned to the ONUs 4-1 to 4-n, respectively. λn is assigned.

In addition, this invention also includes the invention attached to the following.
(Supplementary note 1) An optical wavelength assignment method for assigning reception wavelengths of a plurality of reception-side apparatuses in an optical communication system using a wavelength division multiplexing transmission system,
Transmitting the longest wavelength among the wavelengths of light used in communication between the transmission-side device and each reception-side device from the transmission-side device to each reception-side device;
Measuring the transmission loss of the longest wavelength at each receiving device;
Notifying the transmitting device of transmission loss measured from each receiving device;
And a step of allocating from the longest receiving wavelength in order from the receiving device with the largest transmission loss based on the transmission loss notification from each receiving device in the transmitting device. Method.
(Supplementary Note 2) The number of the plurality of receiving side devices is n, n is an integer of 2 or more,
The transmission loss of the longest wavelength λ1 measured in the measuring step is l1 to ln, l1>l2>...> ln,
The assigning step assigns the received wavelengths λ1 to λn in the order of the receiving side devices having transmission losses 11 to ln, and λ1>λ2>. Method.
(Supplementary note 3) The optical wavelength allocation method according to supplementary note 1 or 2, wherein the assigning step assigns reception wavelengths in an arbitrary order to two or more reception-side devices having the same transmission loss.
(Additional remark 4) The said arbitrary order is a predetermined order or the order determined according to ID of each receiving side apparatus, The optical wavelength allocation method of Additional remark 3 characterized by the above-mentioned.
(Supplementary note 5) The optical communication system is a WDM-PON system, the transmission side device is an OSU, and each reception side device is an ONU. Optical wavelength allocation method.
(Supplementary note 6) An optical communication system using a wavelength division multiplexing transmission system,
A transmitting device;
A plurality of receiving side devices capable of communicating with the transmitting side device via an optical transmission line;
The transmission side device includes transmission means for transmitting the longest wavelength among the wavelengths of light used in communication with each reception side device to each reception side device,
Each receiving side device includes a measuring unit that measures the transmission loss of the longest wavelength, and a notification unit that notifies the transmitting side device of the measured transmission loss,
The transmission side device further comprises wavelength allocation means for allocating from the longest reception wavelength in order from the reception side device having the largest transmission loss based on the transmission loss notification from each reception side device. Optical communication system.
(Supplementary note 7) The number of the plurality of receiving side devices is n, n is an integer of 2 or more,
The transmission loss of the longest wavelength λ1 measured by the measuring means of each receiving device is 11 to ln, l1>l2>...> ln,
The wavelength allocating means of the transmission side apparatus allocates reception wavelengths λ1 to λn in the order of the reception side apparatuses of transmission losses 11 to ln, and λ1>λ2>. 6. The optical communication system according to 6.
(Supplementary note 8) The wavelength assignment means of the transmission side device assigns reception wavelengths in any order to two or more reception side devices having the same transmission loss. Optical communication system.
(Supplementary note 9) The optical communication system according to supplementary note 8, wherein the arbitrary order is a predetermined order or an order determined according to an ID of each receiving-side apparatus.
(Supplementary note 10) The optical communication system according to any one of supplementary notes 6 to 9, wherein the transmission side device is an OSU, and each reception side device is an ONU and constitutes a WDM-PON system.
(Supplementary Note 11) A transmission-side apparatus that performs optical communication with a plurality of reception-side apparatuses using a wavelength division multiplex transmission method,
Transmitting means for transmitting the longest wavelength among the wavelengths of light used in communication between the transmitting device and each receiving device to each receiving device;
Based on the notification of transmission loss from each receiving-side device for the longest transmitted wavelength, the wavelength allocation means for assigning from the longest receiving wavelength in order from the receiving device with the largest transmission loss, Sender device.
(Additional remark 12) It is the receiving side apparatus which performs optical communication with a transmitting side apparatus using a wavelength division multiplexing transmission system,
Receiving means for receiving the longest wavelength among the wavelengths of light used in communication between the receiving apparatus and the transmitting apparatus;
Measuring means for measuring the transmission loss of the longest wavelength;
A receiving-side apparatus comprising: a notification unit that notifies the transmitting-side apparatus of the measured transmission loss.

  While the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope of the present invention.

It is a block diagram explaining operation | movement of one Example of the optical communication system of this invention. It is a block diagram explaining operation | movement of an Example. It is a timing chart explaining operation | movement of an Example. It is a figure explaining the transmission loss measurement process of ONU.

Explanation of symbols

1 WDM-PON system 2 OSU
3 Optical couplers 4-1 to 4-n ONU
11, 12-1 to 12-n optical fiber cable

Claims (5)

An optical wavelength allocation method for allocating reception wavelengths of a plurality of reception side devices in an optical communication system using a wavelength division multiplexing transmission system,
Transmitting the longest wavelength among the wavelengths of light used in communication between the transmission-side device and each reception-side device from the transmission-side device to each reception-side device;
Measuring the transmission loss of the longest wavelength at each receiving device;
Notifying the transmitting device of transmission loss measured from each receiving device;
And a step of allocating from the longest receiving wavelength in order from the receiving device with the largest transmission loss based on the transmission loss notification from each receiving device in the transmitting device. Method. The number of the plurality of receiving side devices is n, where n is an integer of 2 or more,
The transmission loss of the longest wavelength λ1 measured in the measuring step is l1 to ln, l1>l2>...> ln,
2. The optical wavelength according to claim 1, wherein the assigning step assigns reception wavelengths λ <b> 1 to λn in the order of receiving devices having transmission losses 11 to ln, and λ <b>1> λ <b>2>. Assignment method. An optical communication system using a wavelength division multiplexing transmission system,
A transmitting device;
A plurality of receiving side devices capable of communicating with the transmitting side device via an optical transmission line;
The transmission side device includes transmission means for transmitting the longest wavelength among the wavelengths of light used in communication with each reception side device to each reception side device,
Each receiving side device includes a measuring unit that measures the transmission loss of the longest wavelength, and a notification unit that notifies the transmitting side device of the measured transmission loss,
The transmission side device further comprises wavelength allocation means for allocating from the longest reception wavelength in order from the reception side device having the largest transmission loss based on the transmission loss notification from each reception side device. Optical communication system.   4. The optical communication system according to claim 3, wherein the wavelength allocation means of the transmission side apparatus allocates reception wavelengths in an arbitrary order to two or more reception side apparatuses having the same transmission loss.   5. The optical communication system according to claim 3, wherein the transmitting side device is an OSU, and each receiving side device is an ONU, and constitutes a WDM-PON system.

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