WO2018179497A1 - Station-side device migration method, station-side device, station-side device transfer control method, and optical communication system - Google Patents

Abstract

A migration method for a station-side device for an optical communication system, said method including: a step for forming a station-side device so as to be capable of receiving in a reception unit an uplink signal having a wavelength included in a first wavelength band, and a step for forming a station-side device so as to be capable of using at least one wavelength included in a second wavelength band overlapping at least a portion of the first wavelength band to transmit a downlink signal, and capable of receiving an uplink signal by means of a reception unit, and capable of attenuating reflected return light of the downlink signal by means of a wavelength filter at a stage prior to the reception unit.

Description

Station side device migration method, station side device, station side device transmission control method, and optical communication system

The present invention relates to a station side device migration method, a station side device, a station side device transmission control method, and an optical communication system. This application claims priority based on Japanese Patent Application No. 2017-0666011 which is a Japanese patent application filed on March 29, 2017. All the descriptions described in the Japanese patent application are incorporated herein by reference.

The transmission capacity in optical communication has been dramatically increased. In recent years, optical communication having a transmission capacity of 100 Gbps has been proposed. For example, in 100 G-EPON (Ethernet (registered trademark) Passive Optical Network), four optical signals having different wavelengths are transmitted at a speed of 25.8 Gbps (hereinafter referred to as “25 Gbps”). Specifically, these four optical signals are multiplexed according to a wavelength division multiplexing (WDM) system. Wavelength multiplexed light is transmitted through an optical fiber.

For example, US Patent Application Publication No. 2016/0149643 (Patent Document 1) discloses an optical transceiver in which four optical devices each having a transmission rate of 10 Gbps are integrated. The optical transceiver multiplexes four optical signals having different wavelengths from each other, and equivalently realizes transmission speeds of 40 Gbps and 100 Gbps.

US Patent Application Publication No. 2016/0149643

According to an aspect of the present invention, there is provided a migration method for a station-side device for an optical communication system, wherein an uplink signal having a wavelength included in a first wavelength band for a first transmission rate is received by a reception unit of the station-side device. And configuring at least one of the first wavelength band and the second wavelength band included in the second wavelength band for a transmission rate different from the first transmission rate. The transmission unit of the station side device can transmit the downlink signal using one wavelength, the reception unit can receive the uplink signal, and the reflected return light of the downlink signal can be attenuated by the wavelength filter in front of the reception unit In this way, a step of configuring the station side device is provided.

A station apparatus according to an aspect of the present invention includes a receiving unit configured to be able to receive an uplink signal having a wavelength included in a first wavelength band for a first transmission rate, and a first wavelength band A transmitting unit configured to transmit a downlink signal using at least one wavelength included in the second wavelength band having a transmission rate different from the first transmission rate and overlapping at least part of the first transmission rate; A wavelength filter that is provided in the preceding stage and attenuates the reflected return light that returns to the reception unit of the downstream signal.

The station side apparatus transmission control method according to one aspect of the present invention includes a step of receiving an uplink signal having a wavelength included in the first wavelength band for the first transmission rate by the receiving unit of the station side apparatus; A downlink signal using at least one wavelength included in the second wavelength band for a transmission speed different from the first transmission speed and overlapping at least a part of the first wavelength band is transmitted by the transmitter of the station side device A step of transmitting, and a step of attenuating the reflected return light of the downstream signal by a wavelength filter provided in a preceding stage of the receiving unit.

An optical communication system according to an aspect of the present invention includes a first home-side device configured to transmit an uplink signal having a wavelength included in a first wavelength band for a first transmission rate, A second signal configured to receive a downlink signal having at least one wavelength included in a second wavelength band that overlaps at least a part of the first wavelength band and is different from the first transmission speed. A home side device, an optical communication line connected to the first home side device and the second home side device, and a station side device connected to the optical communication line. The station-side device includes a receiving unit configured to receive an upstream signal, a transmitting unit configured to transmit a downstream signal, and reflected return light that is provided upstream of the receiving unit and returns to the downstream signal receiving unit. And a wavelength filter for attenuating.

According to an aspect of the present invention, there is provided a migration method for a station-side device for an optical communication system, wherein an uplink signal having a wavelength included in a first wavelength band for a first transmission rate is received by a reception unit of the station-side device. The transmission unit of the station side device using the at least one wavelength included in the second wavelength band for a transmission rate different from the first transmission rate. Configuring the station side device so that the signal can be transmitted, the uplink signal can be received by the receiving unit, and the reflected return light of the downlink signal can be attenuated by the wavelength filter in the preceding stage of the receiving unit; Replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

A station side device migration method for an optical communication system according to an aspect of the present invention is a station side device migration method including an optical transceiver including a transmission unit, the method being for a first transmission rate. A step of configuring the station-side device so that an upstream signal having a wavelength included in the first wavelength band can be received by the receiving unit of the station-side device, and a second for a transmission rate different from the first transmission rate. The transmission unit can transmit the downlink signal using at least one wavelength included in the wavelength band of the signal, the reception unit can receive the uplink signal, and the reflected return light of the downlink signal is the wavelength at the preceding stage of the reception unit. Configuring the station side device so that it can be attenuated by the filter, and exchanging the optical transceiver to change the number of wavelengths used for the downlink signal.

According to an aspect of the present invention, there is provided a migration method for a station-side device for an optical communication system, wherein an uplink signal having a wavelength included in a first wavelength band for a first transmission rate is received by a reception unit of the station-side device. In the second wavelength band for the transmission speed different from the first transmission speed, overlapping with at least a part of the receivable wavelength band of the receiving unit. The transmitting unit of the station side device can transmit the downlink signal using at least one wavelength, the receiving unit can receive the uplink signal, and the reflected return light of the downlink signal is transmitted by the wavelength filter in the front stage of the receiving unit. Configuring the station-side device to be attenuated, and replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

A station side device migration method for an optical communication system according to an aspect of the present invention is a station side device migration method including an optical transceiver including a transmission unit, the method being for a first transmission rate. A step of configuring the station-side device so that an upstream signal having a wavelength included in the first wavelength band of the first side can be received by the receiving unit of the station-side device, and overlapping at least a part of the receivable wavelength band of the receiving unit, And the transmission unit can transmit the downlink signal using at least one wavelength included in the second wavelength band for the transmission rate different from the first transmission rate, and the reception unit can receive the uplink signal, In addition, the step of configuring the station side apparatus and the optical transceiver are exchanged so that the reflected return light of the downstream signal can be attenuated by the wavelength filter in the front stage of the receiving unit, and used for the downstream signal. And a step of changing the number of that wavelength.

FIG. 1 is a diagram illustrating a configuration example of an optical communication system according to an embodiment. FIG. 2 is a schematic diagram for explaining one example of wavelength arrangement of GE-PON, 10G-EPON, and 100G-EPON. FIG. 3 is a diagram illustrating a configuration example of a station-side apparatus capable of coexisting 10G-EPON and 100G-EPON. FIG. 4 is a schematic diagram for explaining reception of an uplink signal by the station side apparatus shown in FIG. FIG. 5 is a diagram showing another configuration example of the station side apparatus capable of coexisting 10G-EPON and 100G-EPON. FIG. 6 is a schematic diagram for explaining reception of an uplink signal by the station side device shown in FIG. FIG. 7 is a diagram showing one study example of a station side device for coexistence of GE-PON, 10G-EPON, and 100G-EPON. FIG. 8 is a diagram showing another examination example of a station side device for coexistence of GE-PON, 10G-EPON, 25G, 50G, and 100G-EPON. FIG. 9 is a diagram showing still another example of examination of a station side device for coexistence of GE-PON, 10G-EPON, 25G, 50G, and 100G-EPON. FIG. 10 is a diagram for explaining reception of an uplink signal by the station-side apparatus illustrated in FIGS. 7 to 9. FIG. 11 is a diagram illustrating a configuration for solving the problem of an increase in branch loss in the configuration illustrated in FIGS. 7 to 9. FIG. 12 is a diagram illustrating an example of the allocation of the wavelength of the uplink signal for each ODN in the configuration illustrated in FIG. FIG. 13 is a diagram for explaining problems in the configuration of the station-side device shown in FIG. FIG. 14 is a diagram showing the relationship between the wavelength and the RMS spectral width mask according to the upstream wavelength specification of 1000BASE-PX10, which is one of the standards of IEEE802.3. FIG. 15 is a schematic diagram for explaining the spectrum of an FP-LD (Fabry-Perot type semiconductor laser) light source for 1000BASE-PX10. FIG. 16 is a diagram showing the relationship between the wavelength and the RMS spectral width mask according to the 1000BASE-PX20 (20 km) upstream wavelength specification, which is one of the standards of IEEE 802.3. FIG. 17 is a schematic diagram for explaining the spectrum of a single longitudinal mode oscillation type DFB-LD. FIG. 18 is a diagram illustrating an example of an actual specification range of an uplink transmitter applied to GE-PON (1000BASE-PX10). FIG. 19 is a schematic diagram illustrating the characteristics of a wavelength filter for cutting reflected return light having a 100 G downstream wavelength. FIG. 20 is a diagram showing a schematic configuration of one example of a station-side apparatus according to an embodiment of the present invention. FIG. 21 is a diagram for explaining an example of the migration scenario of the station side device. FIG. 22 is a schematic diagram illustrating an example of a wavelength arrangement of the GE-PON upstream wavelength and the 100GE-EPON downstream reflected reflected light at the stage (Day 3) when 100G-EPON is mounted. FIG. 23 is a schematic configuration diagram of an optical communication system in a stage (Day 0) where GE-PON and 10G-EPON coexist. FIG. 24 is a schematic configuration diagram of an optical communication system in a stage (Day 1) in which GE-PON, 10G-EPON, and 25G-EPON coexist. FIG. 25 is a schematic configuration diagram of an optical communication system in a stage (Day 2) in which GE-PON, 10G-EPON, 25G-EPON, and 50G-EPON coexist. FIG. 26 is a schematic configuration diagram of an optical communication system configuration in a stage (Day 3) in which 10G-EPON, 25G-EPON, 50G-EPON, and 100G-EPON coexist. FIG. 27 is a diagram for explaining the overall configuration of the optical communication system according to the embodiment of the present invention. FIG. 28 is a schematic diagram for explaining another example of wavelength arrangement of GE-PON, 10G-EPON, and 100G-EPON. FIG. 29 is a diagram illustrating another example of the migration scenario of the station side device. FIG. 30 is a diagram showing a schematic configuration of another example of the station side apparatus according to the embodiment of the present invention.

[Problems to be solved by this disclosure]
When an optical communication system with a new transmission capacity is introduced, there is a possibility that wavelength arrangement becomes a problem between the optical communication system and an optical communication system with an existing transmission capacity. For example, standardization of the upstream wavelength and downstream wavelength of 100G-EPON is in progress. According to one proposal, the upstream wavelength and downstream wavelength of 100G-EPON can be included in the upstream wavelength band of GE-PON. Therefore, simply, GE-PON and 100G-EPON cannot coexist.

An object of the present disclosure is to enable coexistence of optical communications even when wavelength bands overlap between optical communications having different transmission capacities.
[Effects of the present disclosure]
Based on the above, even when wavelength bands overlap between optical communications having different transmission capacities, the optical communications can be made coexistent.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.

(1) According to one aspect of the present invention, a station side apparatus migration method for an optical communication system transmits an uplink signal having a wavelength included in a first wavelength band for a first transmission rate to a station side apparatus. And the step of configuring the station-side device so that it can be received by the receiver, and included in the second wavelength band that overlaps at least a part of the first wavelength band and has a transmission rate different from the first transmission rate The transmission unit of the station side device can transmit the downlink signal using the at least one wavelength that is transmitted, the reception unit can receive the uplink signal, and the reflected light of the downlink signal is the wavelength filter in the previous stage of the reception unit Configuring the station side device so as to be attenuated by.

According to the above, even when wavelength bands overlap between optical communications having different transmission capacities, the optical communications can be made coexistent.

(2) Preferably, the step of configuring the station-side device so that the transmission unit of the station-side device can transmit a downlink signal using at least one wavelength includes the transmission unit having one wavelength within the second wavelength band. The step of configuring the station side device so that the downlink signal can be transmitted using, and the configuration of the station side device so that the transmission unit can transmit the downlink signal using two or more wavelengths within the second wavelength band Steps.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(3) Preferably, in the migration method of the station side device, the transmission unit can multiplex all of a plurality of predetermined wavelengths in the second wavelength band and transmit the downstream signal, and the reception unit can transmit the upstream signal. And a step of configuring the station side device so that the reflected return light can be attenuated by the wavelength filter.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(4) Preferably, the method further includes the step of replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(5) Preferably, the station side device includes an optical transceiver including at least a transmission unit. The station side apparatus migration method further includes the step of changing the number of wavelengths used for the downlink signal by exchanging the optical transceiver.

According to the above, it is possible to easily increase the transmission capacity of optical communication using the second wavelength band.

(6) A station apparatus according to an aspect of the present invention includes a receiving unit configured to be able to receive an uplink signal having a wavelength included in a first wavelength band for a first transmission rate, A transmission unit configured to transmit a downlink signal using at least one wavelength included in a second wavelength band that overlaps at least a part of the wavelength band and is different from the first transmission rate; A wavelength filter that is provided upstream of the reception unit and attenuates reflected return light that returns to the reception unit of the downstream signal.

According to the above, even when wavelength bands overlap between optical communications having different transmission capacities, a station-side device capable of coexisting those optical communications can be realized.

(7) Preferably, the transmission unit is configured to transmit a downlink signal using one wavelength in the second wavelength band.

According to the above, even when wavelength bands overlap between optical communications having different transmission capacities, a station-side device capable of coexisting those optical communications can be realized.

(8) Preferably, the transmission unit is configured to transmit a downlink signal using two or more wavelengths within the second wavelength band.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(9) Preferably, the transmission unit is configured to be able to transmit a downlink signal by multiplexing all of a plurality of predetermined wavelengths in the second wavelength band.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(10) In the transmission control method for the station side apparatus according to the aspect of the present invention, the reception unit of the station side apparatus receives an uplink signal having a wavelength included in the first wavelength band for the first transmission rate. And a downlink signal using at least one wavelength included in the second wavelength band, which overlaps at least a part of the first wavelength band and is different from the first transmission speed, in the second wavelength band. A step of transmitting by the transmission unit, and a step of attenuating the reflected return light of the downstream signal by a wavelength filter provided in a preceding stage of the reception unit.

According to the above, even when wavelength bands overlap between optical communications having different transmission capacities, it is possible to realize transmission of optical signals in a state in which those optical communications can coexist.

(11) Preferably, the transmitting step includes a step in which the transmitting unit transmits a downlink signal using one wavelength within the second wavelength band.

According to the above, even when wavelength bands overlap between optical communications having different transmission capacities, it is possible to realize transmission of optical signals in a state in which those optical communications can coexist.

(12) Preferably, the transmitting step includes a step in which the transmitting unit transmits a downlink signal using a plurality of wavelengths within the second wavelength band.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(13) Preferably, the transmitting step includes a step in which the transmitting unit multiplexes all of a plurality of predetermined wavelengths in the second wavelength band and transmits a downlink signal.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(14) An optical communication system according to one aspect of the present invention is configured to transmit an uplink signal having a wavelength included in a first wavelength band for a first transmission rate. And a downlink signal having at least one wavelength included in the second wavelength band for a transmission speed different from the first transmission speed and overlapping at least a part of the first wavelength band. A second home-side device; an optical communication line connected to the first home-side device and the second home-side device; and a station-side device connected to the optical communication line. The station-side device includes a receiving unit configured to receive an upstream signal, a transmitting unit configured to transmit a downstream signal, and reflected return light that is provided upstream of the receiving unit and returns to the downstream signal receiving unit. And a wavelength filter for attenuating.

According to the above, even when wavelength bands overlap between optical communications having different transmission capacities, the optical communications can be made coexistent.

(15) Preferably, the transmission unit is configured to transmit a downlink signal using one wavelength within the second wavelength band.

According to the above, even when wavelength bands overlap between optical communications having different transmission capacities, the optical communications can be made coexistent.

(16) Preferably, the transmission unit is configured to transmit a downlink signal using two or more wavelengths within the second wavelength band.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(17) Preferably, the transmission unit is configured to be able to transmit a downlink signal by multiplexing all of a plurality of predetermined wavelengths in the second wavelength band.

Based on the above, even when the transmission capacity of optical communication using the second wavelength band increases, optical communication using the first wavelength band and optical communication using the second wavelength band can coexist. Can do.

(18) Preferably, the first home side apparatus includes a Fabry-Perot type semiconductor laser as a light source for transmitting an upstream signal.

According to the above, the reflected light can be weakened by the wavelength filter while reducing the attenuation of the upstream signal by the wavelength filter in the station side device.

(19) Preferably, the first home apparatus includes a single longitudinal mode distributed feedback semiconductor laser as a light source for transmitting an upstream signal.

According to the above, the reflected light can be weakened by the wavelength filter while reducing the attenuation of the upstream signal by the wavelength filter in the station side device.

(20) According to one aspect of the present invention, a station side apparatus migration method for an optical communication system transmits an uplink signal having a wavelength included in a first wavelength band for a first transmission rate to a station side apparatus. And a step of configuring the station-side device so that it can be received by the receiver, and transmission by the station-side device using at least one wavelength included in the second wavelength band for a transmission rate different from the first transmission rate. The station side device is configured so that the transmission unit can transmit the downlink signal, the reception unit can receive the uplink signal, and the reflected return light of the downlink signal can be attenuated by the wavelength filter in the preceding stage of the reception unit And replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

Based on the above, it is possible to allow optical communications having different transmission capacities to coexist.
(21) A migration method for a station-side device for an optical communication system according to an aspect of the present invention is a migration method for a station-side device including an optical transceiver including a transmission unit, and the method includes the first transmission. A step of configuring the station-side device so that an upstream signal having a wavelength included in the first wavelength band for speed can be received by the receiving unit of the station-side device, and a transmission rate different from the first transmission rate. The transmission unit can transmit a downstream signal using at least one wavelength included in the second wavelength band of the first signal, the upstream signal can be received by the reception unit, and the reflected return light of the downstream signal is transmitted from the reception unit. It comprises the steps of configuring the station side device so that it can be attenuated by the preceding wavelength filter, and changing the number of wavelengths used for the downlink signal by exchanging the optical transceiver.

Based on the above, it is possible to allow optical communications having different transmission capacities to coexist.
(22) According to one aspect of the present invention, a station side apparatus migration method for an optical communication system transmits an uplink signal having a wavelength included in a first wavelength band for a first transmission rate to a station side apparatus. And a second wavelength band for a transmission rate that overlaps at least a part of the receivable wavelength band of the reception unit and that is different from the first transmission rate. The transmission unit of the station side device can transmit the downlink signal using at least one wavelength included in the signal, the uplink signal can be received by the reception unit, and the reflected return light of the downlink signal is transmitted to the upstream of the reception unit. Configuring the station-side device to be attenuated by the wavelength filter, and replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

Based on the above, it is possible to allow optical communications having different transmission capacities to coexist.
(23) A migration method for a station-side device for an optical communication system according to an aspect of the present invention is a migration method for a station-side device including an optical transceiver including a transmission unit, and the method includes a first transmission. Configuring the station-side device so that an uplink signal having a wavelength included in the first wavelength band for speed can be received by the receiving unit of the station-side device, and at least a part of the receivable wavelength band of the receiving unit The transmission unit can transmit a downlink signal using at least one wavelength included in the second wavelength band for a transmission rate different from the first transmission rate, and the reception unit can receive an uplink signal And the step of configuring the station side device so that the reflected return light of the downstream signal can be attenuated by the wavelength filter in the front stage of the receiving unit, and the optical transceiver And a step of changing the number of wavelengths needed.

Based on the above, it is possible to allow optical communications having different transmission capacities to coexist.
[Details of the embodiment of the present invention]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

In the following, “Gbps” may be simply expressed as “G” for simplification. For example, 1 Gbps, 10 Gbps, and 100 Gbps may be represented as “1G”, “10G”, and “100G”, respectively, in the following description.

FIG. 1 is a diagram illustrating a configuration example of an optical communication system according to an embodiment. In FIG. 1, a PON (Passive Optical Network) system 300 is an optical communication system according to an embodiment. The PON system 300 includes a station side device 301, a home side device 302, a PON line 303, and an optical splitter 304. The “station-side device” and “home-side device” can be realized by “OLT (Optical Line Terminal)” and “ONU (Optical Network Unit)”.

The station-side device 301 is installed in, for example, a communication company's office. The station side device 301 mounts a host substrate (not shown). Connected to the host substrate is an optical transceiver (not shown) that converts electrical signals and optical signals into each other.

The home device 302 is installed on the user side. Each of the plurality of home side devices 302 is connected to the station side device 301 via the PON line 303.

The PON line 303 is an optical communication line composed of an optical fiber. The PON line 303 includes a trunk optical fiber 305 and at least one branch optical fiber 306. The optical splitter 304 is connected to the trunk optical fiber 305 and the branch optical fiber 306. A plurality of home devices 302 can be connected to the PON line 303.

The optical signal transmitted from the station side device 301 passes through the PON line 303 and is branched to a plurality of home side devices 302 by the optical splitter 304. On the other hand, the optical signal transmitted from each home apparatus 302 is focused by the optical splitter 304 and sent to the station apparatus 301 through the PON line 303. The optical splitter 304 passively branches or multiplexes the signal from the input signal without requiring any external power supply.

As a high-speed PON system, a wavelength-multiplexed PON system in which a plurality of wavelengths are assigned to an upstream signal or a downstream signal and a plurality of wavelengths are wavelength-multiplexed to form an upstream signal or a downstream signal has been studied. For example, in a 100 Gbps class PON, it is possible to assign a wavelength of 25 Gbps to a signal having a transmission capacity of 25 Gbps per wavelength for upstream and downstream and multiplex them. As an introduction scenario of such a wavelength division multiplexing PON system, a gradual expansion (upgrade) of transmission capacity can be considered.

For example, a scenario is assumed in which 25G-EPON or 50G-EPON is introduced prior to the introduction of 100GE-PON. In the drawings described below, “Day 1”, “Day 2”, “Day 3”, and the like are notations at the stage of expansion of transmission capacity. The name indicating the stage of expansion of the transmission capacity is not particularly limited. For example, the term “generation” may be used to indicate a stage such as “first generation” or “second generation”. In the following description, “migration” means system migration for expansion of transmission capacity. Furthermore, since a system with a small transmission capacity is already popular, a system with a small transmission capacity and a system with a large transmission capacity may coexist. In the following, an embodiment in which GE-PON, 10G-EPON and 100G-EPON coexist will be described.

FIG. 2 is a schematic diagram for explaining one example of wavelength arrangement of GE-PON, 10G-EPON, and 100G-EPON. As shown in FIG. 2, in GE-PON, the wavelength band assigned to the upstream (US) is 1260-1360 nm (1290-1330 nm in the Reduced specification), and the wavelength band assigned to the downstream (DS) is 1480-1500 nm. In 10G-EPON, the wavelength band assigned to the upstream is 1260-1280 nm, and the wavelength band assigned to the downstream is 1575-1580 nm.

Standardization is in progress for wavelengths used in 100G-EPON. In one proposal, for the uplink, four wavelengths λt1 to λt4 used for 25 Gbps transmission are arranged in the wavelength band of 1285 to 1310 nm. On the downstream side, four wavelengths λr1 to λr4 each used for 25 Gbps transmission are arranged in the wavelength band of 1335 to 1360 nm. Therefore, according to the wavelength arrangement shown in FIG. 2, the downstream wavelength band of 100G-EPON overlaps at least a part (the longer wavelength side) of the upstream wavelength band of GE-PON.

The upstream wavelength band and downstream wavelength band of 100G-EPON do not overlap either the upstream wavelength band or downstream wavelength band of 10G-EPON. Therefore, 10G-EPON and 100G-EPON can coexist.

* Expansion from 25G-EPON to 50G-EPON and 100G-EPON can be realized by increasing the number of wavelengths. Therefore, in the drawings described below, a configuration for mounting 25G-EPON corresponding to a system in the previous stage of 100GE-PON is shown unless it is particularly necessary to distinguish.

FIG. 3 is a diagram showing a configuration example of a station-side device capable of coexisting 10G-EPON and 100G-EPON. FIG. 4 is a schematic diagram for explaining reception of an uplink signal by the station side apparatus shown in FIG. With reference to FIGS. 3 and 4, the station side device 301 includes an optical transceiver 141 and an electric processing LSI 43.

The optical transceiver 141 supports lanes of 10 Gbps × 1 and 25 Gbps × 1. The optical transceiver 141 includes an optical wavelength demultiplexer (MUX / DMUX) 42, an electrical processing LSI 43, optical transmitters 51 and 56, and optical receivers 61 and 66.

The optical wavelength demultiplexer 42 is connected to the PON line 303. The optical wavelength multiplexer / demultiplexer 42 is mounted on the optical transceiver 141 in order to transmit a plurality of optical signals having different wavelengths on the PON line 303. Specifically, the optical wavelength demultiplexer 42 multiplexes the optical signal having the wavelength λt0 and the optical signal having the wavelength λt1 and outputs the wavelength multiplexed signal to the PON line 303. On the other hand, the optical wavelength demultiplexer 42 receives the wavelength multiplexed signal from the PON line 303 and separates the wavelength multiplexed signal into two optical signals (wavelengths λr0 and λr1).

The optical transmitter 56 (Tx0) receives an electrical signal from the electrical processing LSI 43 and converts the electrical signal into an optical signal having a wavelength λt0. The optical transmitter 51 (Tx1) receives an electrical signal from the electrical processing LSI 43 and converts the electrical signal into an optical signal having a wavelength λt1. The optical signal with wavelength λt0 is a 10G downstream signal, and the optical signal with wavelength λt1 is a 25G downstream signal.

The optical receiver 66 (Rx0) receives the optical signal having the wavelength λr0 from the PON line 303 through the optical wavelength demultiplexer 42 and converts the optical signal into an electrical signal. The optical receiving unit 66 outputs the electrical signal to the electrical processing LSI 43. The optical receiver 61 (Rx1) receives the optical signal having the wavelength λr1 from the PON line 303 through the optical wavelength demultiplexer 42 and converts the optical signal into an electrical signal. The optical receiver 61 outputs the electrical signal to the electrical processing LSI 43. The optical signal with wavelength λr0 is a 10G downstream signal, and the optical signal with wavelength λr1 is a 25G downstream signal.

The electrical processing LSI 43 performs various processes on the electrical signal output from the optical transceiver 141. On the other hand, the electrical processing LSI 43 generates an electrical signal to be input to the optical transceiver 141. The electrical processing LSI 43 can support multilane distribution control.

In one embodiment, the electrical processing LSI 43 can realize 100 Gbps transmission by four lanes of 25 Gbps. By changing the number of lanes, the electrical processing LSI 43 can support transmission speeds of 25 Gbps, 50 Gbps, and 100 Gbps.

As shown in FIG. 4, the optical signal having the wavelength λr0 and the optical signal having the wavelength λr1 coexist in the PON line 303 by the wavelength division multiplexing (WDM) method. The optical signal with wavelength λr0 and the optical signal with wavelength λr1 can be separated in the station side device 301 by the optical wavelength demultiplexer 42 (see FIG. 3). Therefore, these optical signals can overlap in time.

FIG. 5 is a diagram showing another configuration example of the station side apparatus capable of coexisting 10G-EPON and 100G-EPON. FIG. 6 is a schematic diagram for explaining reception of an uplink signal by the station side device shown in FIG. Referring to FIG. 5, optical transceiver 141A is different from optical transceiver 141 shown in FIG. 3 in that optical receiver 141A includes optical receivers 61A (Rx0 & Rx1) instead of optical receivers 61 and 66. The optical receiver 61A can be realized by a dual rate optical receiver circuit. Various known configurations can be applied to the configuration of the optical receiver 61A.

As shown in FIG. 6, the optical signal having the wavelength λr0 and the optical signal having the wavelength λr1 coexist in the PON line 303 by time division multiplexing (TDM). The optical receiver 61A receives the optical signal with the wavelength λr0 and the optical signal with the wavelength λr1 that are time-division multiplexed. The optical receiver 61A separates the received signal into a 10G upstream signal and a 25G upstream signal.

As shown in FIG. 3 and FIG. 5, 10G-EPON and 100G-EPON can coexist by WDM regarding downstream. Further, 10G-EPON and 100G-EPON can coexist in WDM or TDM with respect to uplink. However, as shown in FIG. 2, the upstream wavelength band of 100GE-PON and the downstream wavelength band overlap with the upstream wavelength band of GE-PON. For this reason, it is necessary to examine the configuration of the station side device in which GE-PON and 100G-EPON can coexist.

FIG. 7 is a diagram showing one study example of a station side device for coexistence of GE-PON, 10G-EPON, and 100G-EPON. The optical transmission / reception unit 131 includes an optical transmission unit 21, an optical reception unit 31, and an optical wavelength multiplexer / demultiplexer 44 in addition to the elements shown in FIG. 3. The optical transmission / reception unit 131 may be realized by a combination of a 10G / 25G optical transceiver and a 1G optical transceiver, or may be realized by a single optical transceiver.

The optical wavelength demultiplexer 42 and the optical wavelength demultiplexer 44 are connected to the optical fiber transmission line 310 via an optical splitter 307 (1 × 2 optical splitter). The optical fiber transmission line 310 is connected to ODNs (Optical Distribution Network) 311 to 314 through an optical splitter 308 (4 × 1 optical splitter).

The optical transmission unit 21 (Tx0 ′) receives the 1G downstream signal from the electrical processing LSI 43 and transmits the downstream signal as an optical signal having the wavelength λt0 ′. The optical receiver 31 (Rx0 ′) receives an upstream signal from a home device (not shown) via the optical fiber transmission line 310 and the optical splitter 308. The optical signal having the wavelength λt0 ′ is a 1G downstream signal. Accordingly, the receivable wavelength band of the optical receiver 31 includes the upstream (US) band (1260 nm-1360 nm) of GE-PON. Since 25G, 50G, and 100G wavelengths are included in a wide range of upstream wavelength bands of GE-PON, the optical transceiver 131 is configured with a 1G optical transceiver and a 25G / 50G / 100G optical transceiver. The optical splitter 307 is an essential component.

FIG. 8 is a diagram showing another examination example of a station side device for coexistence of GE-PON, 10G-EPON, 25G, 50G, and 100G-EPON. 8, the optical transceiver 131 includes an optical transmitter 21, an optical receiver 31, and an optical wavelength demultiplexer 44 in addition to the configuration shown in FIG. The following description will not be repeated for elements common to the elements shown in FIG.

FIG. 9 is a diagram showing still another examination example of a station side device for coexistence of GE-PON, 10G-EPON, 25G, 50G, and 100G-EPON. In FIG. 9, the optical transmission / reception unit 131 includes an optical reception unit 31 </ b> A instead of the optical reception unit 31. The optical receiver 31A is an optical receiver that supports dual rates (1G, 10G). In the configuration shown in FIG. 9, the 10G downstream signal (wavelength λt0) from the optical transmitter 56 is sent to the optical wavelength demultiplexer 44. Further, the optical receiver 66 is omitted.

FIG. 10 is a diagram for explaining the reception of the uplink signal by the station side apparatus shown in FIGS. As shown in FIG. 10, in the first example, a 1G upstream signal (wavelength λr0 '), a 10G upstream signal (wavelength λr0), and a 25G upstream signal (wavelength λr1) are time-division multiplexed. The electrical processing LSI 43 collectively manages the transmission timing of the upstream signal from each home device. Specifically, the electrical processing LSI 43 gives an upstream signal transmission permission to each home-side apparatus.

Since the 10G upstream wavelength band and the 100G upstream wavelength band are different, as shown in the second example of FIG. 10, the 10G upstream signal and the 25G upstream signal may coexist by WDM. However, according to the wavelength arrangement shown in FIG. 2, the 1G upstream wavelength band includes a 10G upstream wavelength band and a 100G upstream wavelength band. Accordingly, the optical wavelength demultiplexer 44 shown in FIGS. 7 to 9 cannot separate the 1G upstream signal from the 10G upstream signal or the 100G upstream signal. The optical receiver 31 is configured to be able to receive light in the 1G upstream wavelength range. Since the 1G upstream wavelength band includes the 10G upstream wavelength band and the 100G upstream wavelength band, the optical receiver 31 receives not only the 1G upstream signal but also the 10G upstream signal and the 100G upstream signal. Since the reception electrical band of the optical receiver 31 is about 1 GHz, the optical receiver 31 can correctly reproduce the 1G upstream signal, but cannot correctly reproduce the 10G upstream signal and the 100G upstream signal. Therefore, the electrical processing LSI 43 can recognize only the 1G upstream signal among the signals transmitted from the optical receiver 31.

On the other hand, according to the configuration shown in FIGS. 7 to 9, it is considered that a branching loss of about 3 dB occurs in the optical splitter 307. In order to cancel this branch loss, it is necessary to increase the power of the optical transmitter 21 and to increase the sensitivity of the optical receiver 31.

FIG. 11 is a diagram showing a configuration for solving the problem of an increase in branch loss in the configuration shown in FIGS. In the configuration shown in FIG. 11, the optical wavelength demultiplexer 42 and the optical wavelength demultiplexer 44 of the station side device 301 are connected to an optical splitter 309 (4 × 2 splitter) on the ODN. Accordingly, the optical splitters 307 and 308 shown in FIG. 9 are integrated into the optical splitter 309. As in the case of the optical splitter 307, when the optical transmission / reception unit 131 includes a 1G optical transceiver and a 25G / 50G / 100G optical transceiver, the optical splitter 309 is an essential component. .

It is known that the branching loss due to the optical splitter 309 is about the same as the branching loss (for example, about 6 to 7 dB) of the optical splitter 308 shown in FIG. According to the configuration shown in FIG. 11, since the optical splitter 307 does not exist, no branching loss due to the optical splitter 307 occurs.

FIG. 12 is a diagram showing an example of the allocation of the wavelength of the uplink signal for each ODN in the configuration shown in FIG. As shown in FIG. 12, since time-division multiplexed uplink signals are transmitted, it is possible to reduce the influence of overlapping between the 1G upstream wavelength band, the 10G upstream wavelength band, and the 100G upstream wavelength band.

FIG. 13 is a diagram for explaining a problem in the configuration of the station-side device shown in FIG. As shown in FIG. 13, for example, reflected return light of a 100G downstream signal is generated. The wavelength of the reflected return light is included in the wavelength band of the 1G upstream signal. Since the downstream signal is continuous light, the reflected return light of the downstream signal necessarily becomes an interference wave.

IEEE 802.3 stipulates that the level of reflected return light (Optical return loss of ODN) of GE-PON and 10G-EPON is 20 dB min. If a 100G-EPON downstream signal (4 wavelengths) of up to +10 dBm per wave is attenuated by 26 dB due to the loss of the branching splitter (6 dB in the round trip) + 20 dB of reflection at the ODN, the reflected return light of 4 wavelengths of -16 dBm is reflected. Return to the station side device 301. The reflected return light passes through the optical wavelength demultiplexer 44 and enters the optical receiver 31A.

A receiver for receiving an upstream signal of GE-PON needs to normally receive light of about -30 dBm. The optical receiver 31A must satisfy this specification. Considering the high sensitivity of the optical receiving unit 31A as described above, the reflected return light is converted into a wavelength filter so that the intensity of the reflected return light of the 100G downstream signal is sufficiently reduced before being input to the optical receiving unit 31A. It is necessary to attenuate with.

For example, a filter for attenuating a 100 G downstream signal by about 30 dB is disposed in the front stage of the optical receiver 31 A or the front stage of the optical wavelength demultiplexer 44. With this filter, the input of the reflected return light of the 100G downstream signal to the 1G receiver (optical receiver 31A) is −46 dBm (= −16−30) per wave, and the total of the 4 waves is −40 dBm. The attenuated reflected return light is sufficiently smaller than the 1G upstream signal received by the optical receiver 31A.

However, the upstream wavelength of GE-PON (1260-1360 nm) and the downstream wavelength of 100G-EPON (there are four wavelengths at 1335-1360 nm) are in the same wavelength region. Although the reflected return light of the 100 G downstream signal can be attenuated by the wavelength filter, there is a problem that the reflected return light and the 1 G upstream signal cannot be separated by the optical wavelength demultiplexer 44.

IEEE 802.3, which is a standard related to GE-PON, assumes that a multi-longitudinal mode oscillation type optical transmitter such as FP-LD (Fabry-Perot type semiconductor laser) is used for an upstream transmitter. In the case of a multi-longitudinal mode oscillation type optical transmitter, the RMS (root mean square) spectral width has a great influence on transmission characteristics. For this reason, the multi-longitudinal mode oscillation type optical transmitter is required to have a narrower RMS spectral width as the oscillation wavelength of the transmitter becomes farther from the zero dispersion wavelength (about 1310 nm) of the optical fiber.

FIG. 14 is a diagram showing the relationship between the wavelength and the RMS spectral width mask according to the upstream wavelength specification of 1000BASE-PX10, which is one of the standards of IEEE802.3. FIG. 15 is a schematic diagram for explaining the spectrum of an FP-LD (Fabry-Perot type semiconductor laser) light source for 1000BASE-PX10.

FP-LD is generally used for multi-longitudinal mode oscillation type optical transmitters. Generally, the RMS spectrum width of the FP-LD of the multi-longitudinal mode oscillation type optical transmitter is about 1.5 to 3 nm. In general, the temperature change of the center wavelength is large in the FP-LD. In the example shown in FIG. 15, the temperature change of the center wavelength of the FP-LD is about 40 nm. Therefore, the upstream transmitter using the FP-LD light source can satisfy the mask specification of 1000BASE-PX10 shown in FIG.

FIG. 16 is a diagram showing the relationship between the wavelength and the RMS spectral width mask according to the 1000BASE-PX20 (20 km) upstream wavelength specification, which is one of the standards of IEEE 802.3. As shown in FIG. 16, in 1000BASE-PX20, the width of the allowable RMS spectrum is smaller than that in 1000BASE-PX10. In FP-LD, it is difficult to satisfy the mask specification of 1000BASE-PX20. In order to satisfy the mask specification of 1000BASE-PX20, an upstream transmitter using a single longitudinal mode oscillation type DFB-LD (distributed feedback semiconductor laser) element is generally used.

FIG. 17 is a schematic diagram for explaining the spectrum of a single longitudinal mode oscillation type DFB-LD. As shown in FIG. 17, the single longitudinal mode oscillation type DFB-LD has the characteristics that the RMS spectral width is smaller than that of the FP-LD and the temperature change of the center wavelength is small. For example, in the example shown in FIG. 17, the temperature change of the center wavelength of the DFB-LD is about 7 nm. With the DFB-LD, it is possible to achieve an upstream wavelength in a band of 1290 nm to 1330 nm, which is sufficiently narrow with respect to the specification of 1260 nm to 1360 nm in IEEE.

When FP-LD is used as the light source of the GE-PON upstream transmitter, the upstream wavelength specification is defined as a wavelength band of 1260-1360 nm. Since the wavelength band of the 100G downstream signal overlaps a part of the wavelength band of the 1G upstream signal (long wavelength side band), the 1G upstream signal and the reflected return light of the 100G downstream signal are separated by the optical wavelength demultiplexer. Is difficult. On the other hand, when DFB-LD is used as the light source of the GE-PON upstream transmitter, the upstream wavelength is defined and operated in a band slightly narrower than the band of FP-LD, such as 1290-1330 nm. There are many cases. When the DFB-LD is used as the light source of the GE-PON upstream transmitter and the wavelength of the 100 G downstream signal is arranged at 1335 nm or more, the 1 G upstream wavelength band is shorter than the 100 G downstream wavelength band. Although located on the side, unlike the case of FP-LD, it is far from the band of the 100G downstream wavelength. Therefore, the reflected return light of the 100G downstream signal and the 1G upstream signal can be separated by the optical wavelength demultiplexer. On the other hand, when FP-LD is used as the light source of the GE-PON upstream transmitter, the upstream wavelength specification is defined within the wavelength band of 1260-1360 nm. When FP-LD is used as the light source of the upstream transmitter, it is considered difficult to separate the reflected return light having the wavelength of 100G-EPON downstream by the wavelength demultiplexer.

FIG. 18 is a diagram showing an example of an actual specification range of an uplink transmitter applied to GE-PON (1000BASE-PX10). In order to satisfy the transmission wavelength mask defined by IEEE 802.3, the specification range of the center wavelength is 1260-1360 nm. On the other hand, the specification range of the center wavelength of the actual optical transceiver is defined to be, for example, 1270 nm or more and 1350 nm or less in consideration of the RMS spectrum width of the FP-LD.

The RMS spectrum width of FP-LD is generally about 2 nm to 3 nm. When the center wavelength is 1350 nm and the RMS spectral width is 3 nm, 68% of the optical output power falls within the range of 1347-1353 nm, and 95% of the optical output power falls within the range of 1343-1356 nm.

FIG. 19 is a schematic diagram illustrating the characteristics of a wavelength filter for cutting reflected return light having a 100 G downstream wavelength. FIG. 20 is a diagram showing a schematic configuration of one example of a station-side apparatus according to an embodiment of the present invention. Referring to FIG. 19 and FIG. 20, the station side device 301 includes optical transceivers 151A and 151B. The optical transceiver 151A is an optical transceiver for 25G / 50G / 100G-EPON, and includes an optical wavelength multiplexer / demultiplexer 42, an optical transmitter 51 (Tx1), and an optical receiver 61 (Rx1). The optical transceiver 151B is an optical transceiver for 1G and 10G, and includes an optical wavelength demultiplexer 44, an optical transmitter 21 (Tx0 '), and an optical receiver 31A (Rx0). The following description will not be repeated for the same elements as those shown in FIG.

A wavelength filter 71 for attenuating reflected return light having a wavelength of 100 G downstream is disposed in front of the optical wavelength demultiplexer 44. The wavelength filter 71 has a characteristic of attenuating light having an upstream wavelength of 1353 nm or less and light having a downstream wavelength of 1490 nm to 1580 nm while attenuating light having an upstream wavelength of 1357 nm or more and 1360 nm or less. Thus, the wavelength filter 71 receives the reflected return light of one wavelength (λt1) of the 100G downstream signal while receiving the upstream signal of the GE-PON with a slight filter loss (for example, about 0.5 dB) even in the worst case. Can be cut.

In the case of the wavelength filter 71 having the above pass band, the reflected light of the signal having the wavelengths λt2, λt3, and λt4 among the 100G downstream signals cannot be cut by the wavelength filter 71. Therefore, in this embodiment, with the migration of the station-side device 301, the wavelength filter is replaced, and the reflected return light of the signal having the wavelengths λt2, λt3, and λt4 is cut. As the steps progress from Day 0 to Day 3, the number of wavelengths used for the 100G downlink signal increases, so the wavelength band of the 100G downlink signal widens and more overlaps with the wavelength band of the 1G uplink signal. In this embodiment, the wavelength filter 71 is replaced with a wavelength filter capable of attenuating the reflected return light of the 100 G downstream signal in such a case.

FIG. 21 is a diagram for explaining an example of the migration scenario of the station side device. 20 and 21, GE-PON (1000BASE-PX10), GE-PON (1000BASE-PX20), and 10G-EPON are mounted in the Day 0 stage. That is, GE-PON and 10G-EPON coexist. At this stage, it is not necessary to provide a wavelength filter for cutting the reflected return light of the 100G downstream signal in the station side device.

At the stage of Day 1, 25G-EPON is mounted, and GE-PON, 10G-EPON and 25G-EPON coexist. 50G-EPON and 100G-EPON have not been installed or are not in operation. At this stage, in order to cut the reflected return light of the 25G downstream signal, the upstream wavelength light of 1353 nm or less and the downstream wavelength light of 1490 nm to 1580 nm are passed, while the upstream wavelength light of 1357 nm to 1360 nm is attenuated. The wavelength filter to be provided is provided on the reception side of the 1G upstream signal of the station side device (the front stage of the optical wavelength demultiplexer 44).

At the stage of Day 2, 50G-EPON is mounted, and GE-PON, 10G-EPON, 25G-EPON and 50G-EPON coexist. 100G-EPON has not been installed or is in a suspended state. In the scenario shown in FIG. 21, at the stage of Day 2, the home device conforming to GE-PON (1000BASE-PX10) is upgraded to a home device for 10G-EPON.

The wavelength arrangement of downstream signals in 50G-EPON is 1359 ± 1 nm and 1349 ± 1 nm. In order to cut the reflected return light of the downstream signals of 25G-EPON and 50G-EPON, the wavelength filter used in the Day 1 stage is replaced with a wavelength filter having a shorter cutoff wavelength. Specifically, a wavelength filter 71 that passes light having an upstream wavelength of 1330 nm or less and light having a downstream wavelength of 1490 nm to 1580 nm while attenuating light having an upstream wavelength of 1335 nm to 1360 nm is a 1G upstream signal of the station side device. Are provided on the receiving side (the front stage of the optical wavelength demultiplexer 44). In the Day2 stage, the transmitter of the station side device 301 uses the more wavelengths (wavelengths λd1 and λd2 shown in FIG. 21) included in the 100G-EPON downstream wavelength band as compared to the Day1 stage. Send. In this embodiment, the wavelength filter used in the Day 1 stage is not only the reflected return light of the 25 G downstream signal (downstream signal of the wavelength λd1) in the Day1 stage, but also the added downstream signal (downstream of the wavelength λd2). In order to attenuate the reflected return light of the signal), it is replaced with a wavelength filter having a shorter cutoff wavelength.

At the stage of Day 3, 100G-EPON is mounted, and GE-PON, 10G-EPON, 25G-EPON, 50G-EPON and 100G-EPON coexist. The wavelength arrangement of downstream signals in 100G-EPON is 1359 ± 1 nm, 1349 ± 1 nm, 1344 ± 1 nm, and 1339 ± 1 nm. In order to cut the reflected return light of the downstream signals of 25G-EPON, 50G-EPON and 100G-EPON, the light of the upstream wavelength of 1330 nm or less and the light of the downstream wavelength of 1490 nm to 1580 nm are passed, while 1335 nm or more and 1360 nm or less The wavelength filter 71 for attenuating the upstream wavelength light is provided on the receiving side of the 1G upstream signal of the station side device (the front stage of the optical wavelength demultiplexer 44).

FIG. 22 is a schematic diagram illustrating an example of the wavelength arrangement of the GE-PON upstream wavelength and the 100GE-EPON downstream return reflected light at the stage where the 100G-EPON is mounted (Day 3). As a premise, it is assumed that the home device of GE-PON conforms to 1000BASE-PX20. That is, this home-side apparatus has a single longitudinal mode oscillation type DFB-LD element as a light source for transmitting an upstream signal. Even when the temperature change of the center wavelength is taken into consideration, the upstream wavelength of the GE-PON can be sufficiently separated from the wavelength of the reflected return light of the downstream signal of 100 G-EPON to the short wavelength side. Therefore, it is possible to use a wavelength filter that transmits light having a wavelength of 1330 nm or less and attenuates light having a wavelength of 1335 nm or more. The wavelength filter can not only pass the upstream signal of the GE-PON with a small loss, but can cut the reflected return light of the downstream signal of the 100 G-EPON.

FIG. 23 is a schematic configuration diagram of an optical communication system at a stage (Day 0) where GE-PON and 10G-EPON coexist. An optical transceiver 151, electrical processing LSIs 2A and 2B, and an upstream bandwidth allocation control LSI 3 are mounted on the host substrate 1A. The optical transceiver 151 can support both 1 Gbps (wavelength λ 0 ′) and 10 Gbps (wavelength λ 0) transmission capacities.

The electric processing LSI 2A supports one lane (10 Gbps × 1) of 10 Gbps. The electrical processing LSI 2A receives a 10G upstream signal from the optical transceiver 151 and outputs a 10G downstream signal to the optical transceiver 151.

The electric processing LSI 2B supports one lane of 1 Gbps (1 Gbps × 1). The electrical processing LSI 2B receives the 1G upstream signal from the optical transceiver 151 and outputs the 1G downstream signal to the optical transceiver 151.

Each of the electrical processing LSIs 2A and 2B is configured to be able to communicate with the outside of the host substrate 1A. The uplink bandwidth allocation control LSI 3 executes control for allocating the bandwidth of the uplink signal transmitted by each of the plurality of home side devices 302.

FIG. 24 is a schematic configuration diagram of an optical communication system at a stage (Day 1) in which GE-PON, 10G-EPON, and 25G-EPON coexist. In the Day 1 stage, the home side apparatus 302 corresponding to 25 Gbps is introduced into the optical communication system. The host substrate 1A may be replaced with a host substrate 1B. On the host substrate 1B, an optical transceiver 161, electrical processing LSIs 2, 2A, 2B, and an upstream bandwidth allocation control LSI 3 are mounted.

The optical transceiver 161 can support 1 Gbps (wavelength λ0 ′), 10 Gbps (wavelength λ0), and 25 Gbps (wavelength λ1). A plurality of optical transceivers supporting a single wavelength or a plurality of wavelengths may be employed in place of the optical transceiver 161.

The electric processing LSI 2 supports 4 lanes of 25 Gbps (25 Gbps × 4). The electrical processing LSI 2 receives a 25 G upstream signal from the optical transceiver 141 and transmits a 25 G downstream signal to the optical transceiver 141.

FIG. 25 is a schematic configuration diagram of an optical communication system at a stage (Day 2) in which GE-PON, 10G-EPON, 25G-EPON and 50G-EPON coexist. A home side device 302 corresponding to 50 Gbps is introduced into the optical communication system. In the Day 2 stage, the optical transceiver 161 (see FIG. 24) is replaced with the optical transceiver 171. The optical transceiver 171 is an optical transceiver of 1 Gbps (wavelength λ0 ′), 10 Gbps (wavelength λ0), and 25 Gbps × 2 wavelengths (wavelengths λ1 and λ2). A plurality of optical transceivers supporting a single wavelength or a plurality of wavelengths may be employed instead of the optical transceiver 171.

FIG. 26 is a schematic configuration diagram of an optical communication system configuration in a stage (Day 3) in which 10G-EPON, 25G-EPON, 50G-EPON and 100G-EPON coexist. In the Day 3 stage, the optical transceiver 171 (see FIG. 25) is replaced with the optical transceiver 181. The optical transceiver 181 is an optical transceiver of 1 Gbps (wavelength λ0 ′), 10 Gbps (wavelength λ0), and 25 Gbps × 4 wavelengths (wavelengths λ1, λ2, λ3, λ4). A plurality of optical transceivers supporting a single wavelength or a plurality of wavelengths may be employed instead of the optical transceiver 181.

FIG. 27 is a diagram for explaining the overall configuration of the optical communication system according to the embodiment of the present invention. A home apparatus is connected to each of the ODNs 311 to 314 via an optical splitter. In FIG. 27, ODN 311 representatively shows home devices 302a, 302b, 302c, and 302d connected via an optical splitter 315 (4 × 1 optical splitter).

The home-side device 302a is a home-side device compliant with GE-PON (1000BASE-PX10), and includes a WDM filter 81a, an optical transmission unit 82a, and an optical reception unit 83a. The WDM filter 81a is a filter for separating a GE-PON upstream signal (wavelength of 1260-1360 nm) and a GE-PON downstream signal (wavelength of 1480-1500 nm).

The optical transmitter 82a includes a semiconductor laser (LD) 84a as a light source. The semiconductor laser 84a is an FP-LD. The optical receiver 83a includes a photodiode (PD) 86a as a light receiving element.

The home device 302b is a home device compliant with GE-PON (1000BASE-PX20), and includes a WDM filter 81b, an optical transmitter 82b, and an optical receiver 83b. Similar to the WDM filter 81a, the WDM filter 81b is a filter for separating the GE-PON upstream signal (wavelength of 1260-1360 nm) and the GE-PON downstream signal (wavelength of 1480-1500 nm).

The optical transmitter 82b includes a semiconductor laser 84b and an isolator 85b. The semiconductor laser 84b is a DFB-LD. The optical receiver 83b includes a photodiode 86b.

The home side device 302c is a home side device compliant with 10G-EPON, and includes a WDM filter 81c, an optical transmission unit 82c, and an optical reception unit 83c. The WDM filter 81c is a filter for separating a 10G-EPON upstream signal (wavelength of 1260-1280 nm) and a 10G-EPON downstream signal (wavelength of 1575-1580 nm).

The optical transmitter 82c includes a semiconductor laser 84c and an isolator 85c. The semiconductor laser 84c is a DFB-LD. The light receiving unit 83c includes a photodiode 86c.

The home side device 302d is a home side device compliant with 25G-EPON, and includes a WDM filter 81d, an optical transmission unit 82d, and an optical reception unit 83d. The WDM filter 81d is a filter for separating a 25G-EPON upstream signal (wavelength of 1287 to 1290 nm) and a 25G-EPON downstream signal (wavelength of 1357 to 1360 nm).

The optical transmitter 82d includes a semiconductor laser 84d and an isolator 85d. The semiconductor laser 84d is a DFB-LD. The optical receiver 83d includes a photodiode 86d.

Uplink signals transmitted from each of the home side devices 302 a to 302 d are reflected by the ODN 311. The reflected return light of the upstream signal (attenuated by 20 dB or more) is input to each of the home side devices 302a, 302b, 302c, and 302d. Further, a downlink signal (attenuated by 15 dB to 29 dB in the ODN) having a transmission rate different from the transmission rate of the home device is input to each home device as interference light.

On the receiving side of the home side apparatus 302a, the WDM filter 81a can cut the reflected return light from the ODN 311 of the 25G downstream signal and the 25G upstream signal. On the transmission side of the home side apparatus 302a, reflected return light from the ODN 311 of the 25G downstream signal and the 25G upstream signal is incident. Generally, the FP-LD transmitter has high resistance to reflected return light. Due to the reflection return light resistance of the semiconductor laser 84a, the influence of the return light to the semiconductor laser 84a can be reduced without an isolator.

On the receiving side of each of the home side devices 302b and 302c, the WDM filter (WDM filters 81b and 81c) can cut the 25G downstream signal and the reflected return light from the ODN 311 of the 25G upstream signal. On the transmitting side of each of the home side devices 302b and 302c, the isolator (85b and 85c) can cut the reflected return light from the ODN 311 of the 25G downstream signal and the 25G upstream signal.

A 1G downlink signal and a 10G downlink signal are input to the home device 302d. These downstream signals are cut by the WDM filter 81d. Therefore, the influence of the 1G downlink signal and the 10G downlink signal can be avoided on both the reception side and the transmission side of the home side apparatus 302d.

The reflected return light from each ODN 311 of the 1G upstream signal and the 10G upstream signal is input to the home-side apparatus 302d. On the receiving side of the home side apparatus 302d, the reflected return light can be cut by the WDM filter 81d. On the transmitting side of the home device 302d, the reflected return light can be cut by the isolator 85d. Therefore, the influence of the reflected return light from the ODN 311 of the 1G upstream signal and the 10G upstream signal can be avoided on both the reception side and the transmission side of the home side apparatus 302d.

The station side device 301 includes optical transceivers 151A and 151B. The optical transceiver 151 </ b> A includes optical transmitters 51 and 56 and an optical receiver 61. The optical transmitter 51 includes a semiconductor laser 51a and an isolator 51b. The optical transmitter 56 includes a semiconductor laser 56a and an isolator 56b. The optical receiver 61 includes a photodiode 61a.

The optical transceiver 151B includes an optical transmitter 21 and an optical receiver 32. The optical transmitter 21 includes a semiconductor laser 21a and an isolator 21b. The optical receiver 32 includes a photodiode 32a. The optical receiver 32 is an optical receiver that supports dual rates (1G, 10G). That is, the receivable wavelength band of the optical receiver 31A includes the 1G upstream wavelength band (1260 nm-1360 nm). This wavelength band includes a 10G upstream wavelength band and a 100G upstream wavelength band.

DFB-LD is used for all of the semiconductor lasers 51a, 56a, and 21a that are light sources. For each of the optical transmitters 51, 56, and 21, the reflected light of the upstream signal and the downstream signal from the station side device 301 is reflected to the semiconductor laser (51 a, 56 a, 21 a) by the isolator (51 b, 56 b, 21 b). Input can be prevented.

The optical wavelength demultiplexer 42 passes only the 25G upstream signal out of the input optical signal and the input reflected return light to the optical receiver 61. Further, uplink signals from the home side devices 302a to 302d are time-division multiplexed. Therefore, the reception of the 25G upstream signal by the optical receiver 61 can be prevented from being affected by the upstream signal of other transmission rates and the reflected return light.

A wavelength filter 71 is provided in the preceding stage of the optical wavelength demultiplexer 44. The reflected light of the 25G downstream signal is cut by the wavelength filter 71. The optical wavelength demultiplexer 44 passes only the upstream optical signal out of the upstream optical signal, the 1G downstream reflected reflected light, and the 10G downstream reflected reflected light input from the ODN side, to the optical receiver 32. Further, uplink signals from the home side devices 302a to 302d are time-division multiplexed. Therefore, the reception of the 1G upstream signal and the 10G upstream signal by the optical receiver 32 can be prevented from being affected by the reflected return light of the 25G upstream signal and the downstream signal from the station side device 301.

The embodiment of the present invention is not limited to be realized only in the case of the wavelength arrangement shown in FIG. FIG. 28 is a schematic diagram for explaining another example of wavelength arrangement of GE-PON, 10G-EPON, and 100G-EPON. For 100 GE-PON upstream, three wavelengths (λr2, λr3, λr4) for transmission of 25 Gbps are arranged in the wavelength band of 1285-1310 nm, and one wavelength is the same wavelength as the upstream wavelength band of 10G-EPON. Arranged in a belt. In this respect, the wavelength arrangement shown in FIG. 28 is different from the wavelength arrangement shown in FIG. However, the embodiment of the present invention can also be applied to the case of the wavelength arrangement shown in FIG.

Also, the migration scenario of the station side device is not limited as shown in FIG. FIG. 29 is a diagram illustrating another example of the migration scenario of the station side device. Referring to FIG. 29, 10G-EPON is not introduced in Day 0. In this respect, the scenario shown in FIG. 29 is different from the scenario shown in FIG.

In the case of the scenario shown in FIG. 29, the station side device can implement the function of the 10G optical transceiver on the 25G / 50G / 100G optical transceiver side. FIG. 30 is a diagram showing a schematic configuration of another example of the station side apparatus according to the embodiment of the present invention. As shown in FIG. 30, the optical transceiver 131 includes an optical transceiver 151C and an optical transceiver 151D. The optical transceiver 151C is a 25G / 50G / 100G optical transceiver, and includes an optical wavelength multiplexer / demultiplexer 42, an optical transmitter 51, an optical transmitter 56, and an optical receiver 61. The optical transceiver 151D is a 1G optical transceiver, and includes an optical wavelength demultiplexer 44, an optical transmitter 21, and an optical receiver 31.

In the optical transceiver 151A, an optical transmitter 56 for transmitting a 10G downstream signal (wavelength λt0) and an optical transmitter 51 for transmitting a 25G downstream signal (wavelength λt0) are coupled to the optical wavelength demultiplexer 42. The The optical receiver 61 can receive an uplink signal at a dual rate of 25 Gbps and 10 Gbps.

It should be considered that the embodiment disclosed this time is illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

1A, 1B Host board, 2, 2A, 2B, 43 Electrical processing LSI, 3 Uplink bandwidth allocation control LSI, 21, 51, 56, 82a, 82b, 82c, 82d Optical transmitter, 21a, 51a, 56a, 84a, 84b , 84c, 84d semiconductor lasers, 21b, 51b, 56b, 85b, 85c, 85d isolators, 31, 31A, 32, 61, 61A, 66, 83a, 83b, 83c, 83d, optical receivers 32a, 61a, 86b, 86c, 86d photodiode, 42, 44 optical wavelength demultiplexer, 71 wavelength filter, 81a, 81b, 81c, 81d WDM filter, 131 optical transceiver, 141, 141A, 151, 151A, 151B, 151C, 151D, 161, 171, 181 Optical transceiver, 300 PON system 301 station side device, 302,302a, 302b, 302c, 302d network unit, 303 PON line, 304,307,308,309,315 optical splitter, 305 trunk optical fiber, 306 branch optical fiber 310 optical fiber transmission line.

Claims (23)

1. A station side device migration method for an optical communication system, comprising:
   Configuring the station side device such that an upstream signal having a wavelength included in the first wavelength band for the first transmission rate can be received by the receiving unit of the station side device;
   The transmitter of the station side device uses at least one wavelength included in a second wavelength band for a transmission speed different from the first transmission speed and overlapping at least a part of the first wavelength band. The station-side device so that it can transmit a downlink signal, can receive the uplink signal by the receiving unit, and can attenuate the reflected return light of the downlink signal by a wavelength filter in the preceding stage of the receiving unit The station side apparatus migration method comprising the steps of:
2. The step of configuring the station side device so that the transmitting unit of the station side device can transmit the downlink signal using the at least one wavelength,
   Configuring the station-side device so that the transmission unit can transmit the downlink signal using one wavelength within the second wavelength band; and
   The station side apparatus according to claim 1, further comprising a step of configuring the station side apparatus so that the transmission unit can transmit the downlink signal using two or more wavelengths within the second wavelength band. Migration method.
3. The transmitter is capable of transmitting all of the plurality of predetermined wavelengths within the second wavelength band to transmit the downlink signal, the receiver is capable of receiving the uplink signal, and The station side apparatus migration method according to claim 1, further comprising a step of configuring the station side apparatus so that reflected return light can be attenuated by the wavelength filter.
4. The station side apparatus migration method according to any one of claims 1 to 3, further comprising a step of replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.
5. The station side device includes an optical transceiver including at least the transmission unit,
   The station side apparatus migration method according to any one of claims 1 to 4, further comprising a step of changing the number of wavelengths used for the downlink signal by exchanging the optical transceiver.
6. A receiver configured to be able to receive an upstream signal having a wavelength included in the first wavelength band for the first transmission rate;
   A configuration in which a downlink signal can be transmitted using at least one wavelength included in a second wavelength band that overlaps at least a part of the first wavelength band and has a transmission speed different from the first transmission speed. The transmitted part,
   A station-side device, comprising: a wavelength filter that is provided in a preceding stage of the receiving unit and attenuates reflected return light returning to the receiving unit of the downlink signal.
7. The station-side device according to claim 6, wherein the transmission unit is configured to be able to transmit the downlink signal using one wavelength within the second wavelength band.
8. The station-side device according to claim 6 or 7, wherein the transmission unit is configured to be able to transmit the downlink signal using two or more wavelengths within the second wavelength band.
9. The transmission unit according to any one of claims 6 to 8, wherein the transmission unit is configured to be capable of transmitting the downlink signal by multiplexing all of a plurality of predetermined wavelengths in the second wavelength band. The station side apparatus as described in a term.
10. Receiving an upstream signal having a wavelength included in the first wavelength band for the first transmission rate by the receiving unit of the station side device;
    A downlink signal using at least one wavelength included in a second wavelength band that overlaps at least a part of the first wavelength band and is different from the first transmission speed is transmitted to the station side device. Transmitting by the transmitting unit;
    And a step of attenuating the reflected return light of the downstream signal by a wavelength filter provided in a preceding stage of the receiving unit.
11. 11. The transmission control method for a station-side device according to claim 10, wherein the transmitting step includes a step in which the transmitting unit transmits the downlink signal using one wavelength within the second wavelength band.
12. The transmission control of the station side device according to claim 10 or 11, wherein the transmitting step includes a step in which the transmitting unit transmits the downlink signal using a plurality of wavelengths within the second wavelength band. Method.
13. The transmission step includes a step in which the transmission unit multiplexes all of a plurality of predefined wavelengths in the second wavelength band and transmits the downlink signal. The station side apparatus transmission control method according to claim 1.
14. A first premises device configured to transmit an upstream signal having a wavelength included in a first wavelength band for a first transmission rate;
    A downlink signal having at least one wavelength included in a second wavelength band that overlaps at least a part of the first wavelength band and is different from the first transmission speed is configured to be received. A second home device;
    An optical communication line connected to the first home-side device and the second home-side device;
    A station side device connected to the optical communication line, the station side device,
    A receiving unit configured to receive the uplink signal;
    A transmission unit configured to transmit the downlink signal;
    An optical communication system, comprising: a wavelength filter that is provided in a preceding stage of the receiving unit and attenuates reflected return light of the downlink signal that returns to the receiving unit.
15. The optical communication system according to claim 14, wherein the transmission unit is configured to be able to transmit the downlink signal using one wavelength within the second wavelength band.
16. The optical communication system according to claim 14 or 15, wherein the transmission unit is configured to be able to transmit the downlink signal using two or more wavelengths within the second wavelength band.
17. The transmission unit according to any one of claims 14 to 16, wherein the transmission unit is configured to be capable of transmitting the downlink signal by multiplexing all of a plurality of predetermined wavelengths in the second wavelength band. The optical communication system according to item.
18. The optical communication system according to any one of claims 14 to 17, wherein the first home device includes a Fabry-Perot semiconductor laser as a light source for transmitting the uplink signal.
19. The optical communication system according to any one of claims 14 to 17, wherein the first home device includes a single longitudinal mode distributed feedback semiconductor laser as a light source for transmitting the uplink signal. .
20. A station side device migration method for an optical communication system, comprising:
    Configuring the station side device such that an upstream signal having a wavelength included in the first wavelength band for the first transmission rate can be received by the receiving unit of the station side device;
    The transmission unit of the station side device can transmit a downlink signal using at least one wavelength included in a second wavelength band for a transmission rate different from the first transmission rate, and the reception unit can transmit the uplink signal Configuring the station-side device so that a signal can be received, and the reflected return light of the downlink signal can be attenuated by a wavelength filter in the front stage of the receiving unit;
    Replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.
21. A station side device migration method for an optical communication system, wherein the station side device includes an optical transceiver including a transmitter,
    Configuring the station side device such that an upstream signal having a wavelength included in the first wavelength band for the first transmission rate can be received by the receiving unit of the station side device;
    The transmission unit can transmit a downlink signal using at least one wavelength included in a second wavelength band for a transmission rate different from the first transmission rate, and the reception unit can receive the uplink signal And configuring the station side device so that the reflected return light of the downlink signal can be attenuated by the wavelength filter in the front stage of the receiving unit, and
    And exchanging the optical transceiver to change the number of wavelengths used for the downlink signal.
22. A station side device migration method for an optical communication system, comprising:
    Configuring the station side device such that an upstream signal having a wavelength included in the first wavelength band for the first transmission rate can be received by the receiving unit of the station side device;
    Transmission of the station side device using at least one wavelength that overlaps at least a part of the receivable wavelength band of the receiving unit and is included in a second wavelength band for a transmission speed different from the first transmission speed The station can transmit a downlink signal, the reception unit can receive the uplink signal, and the reflected return light of the downlink signal can be attenuated by a wavelength filter in front of the reception unit. Configuring a side device;
    Replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.
23. A station side device migration method for an optical communication system, wherein the station side device includes an optical transceiver including a transmitter,
    Configuring the station side device such that an upstream signal having a wavelength included in the first wavelength band for the first transmission rate can be received by the receiving unit of the station side device;
    The transmission unit transmits a downlink signal using at least one wavelength that overlaps at least a part of the receivable wavelength band of the reception unit and is included in a second wavelength band for a transmission rate different from the first transmission rate. The station-side device is configured such that the uplink signal can be received by the receiver, and the reflected return light of the downlink signal can be attenuated by the wavelength filter in the preceding stage of the receiver And steps to
    And exchanging the optical transceiver to change the number of wavelengths used for the downlink signal.

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