JP6900997B2 - Station-side device migration method, station-side device, station-side device transmission control method, and optical communication system - Google Patents

Description

The present invention relates to a migration method of a station-side device, a station-side device, a transmission control method of the station-side device, and an optical communication system. This application claims priority based on Japanese Patent Application No. 2017-066011, which is a Japanese patent application filed on March 29, 2017. All the contents of 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 100G-EPON (Ethernet Passive Optical Network), four optical signals having different wavelengths at a speed of 25.8 Gbps (hereinafter referred to as “25 Gbps”) are transmitted. Specifically, these four optical signals are multiplexed according to a wavelength division multiplexing (WDM) method. Wavelength division light is transmitted through an optical fiber.

For example, U.S. 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 to equivalently realize transmission speeds of 40 Gbps and 100 Gbps.

U.S. Patent Application Publication No. 2016/0149643

In the method of migrating a station-side device for an optical communication system according to one aspect of the present invention, an uplink signal having a wavelength included in a first wavelength band for a first transmission rate is received by a station-side device. At least one that overlaps at least a part of the first wavelength band and is included in the second wavelength band for a transmission rate different from the first transmission rate so that it can be received in. The transmitter of the station side device can transmit the downlink signal using one wavelength, 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 previous stage of the receiver. As described above, it is provided with a step of forming a station-side device.

The station-side device according to one aspect of the present invention includes a receiving unit configured to be able to receive an uplink signal having a wavelength included in the first wavelength band for the first transmission speed, and a first wavelength band. A transmitter and a receiver configured to be capable of transmitting a downlink signal using at least one wavelength that overlaps at least a part and is included in a second wavelength band for a transmission speed different from the first transmission speed. It is provided in the previous stage and includes a wavelength filter for attenuating the reflected return light returning to the receiving portion of the downlink signal.

The transmission control method of the station-side device 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 speed by the receiving unit of the station-side device. A downlink signal using at least one wavelength that overlaps at least a part of the first wavelength band and is included in the second wavelength band for a transmission speed different from the first transmission speed is transmitted by the transmission unit of the station side device. It includes a step of transmitting and a step of attenuating the reflected return light of the downlink signal by a wavelength filter provided in front of the receiving unit.

The optical communication system according to one 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, and a first home-side device. A second configured to be able to receive a downlink signal having at least one wavelength overlapping at least a part of one wavelength band and having at least one wavelength included in the second wavelength band for a transmission rate different from the first transmission rate. It includes 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 is provided in front of a receiving unit configured to receive an uplink signal, a transmitting unit configured to be able to transmit a downlink signal, and a receiving unit, and is a reflected return light returning to the receiving unit of the downlink signal. Includes a wavelength filter that attenuates the light.

The method for migrating a station-side device for an optical communication system according to one aspect of the present invention is to receive an uplink signal having a wavelength included in a first wavelength band for a first transmission rate in a receiver of the station-side device. The transmitter of the station-side device is downlinked using at least one wavelength included in the second wavelength band for a transmission rate different from the first transmission rate and the step of configuring the station-side device so that it can be received in. Steps to configure 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 previous stage of the receiving unit. It comprises a step of replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

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

In the method of migrating a station-side device for an optical communication system according to one aspect of the present invention, an uplink signal having a wavelength included in a first wavelength band for a first transmission rate is received by a station-side device. It overlaps with at least a part of the receivable wavelength band of the receiving unit and is included in the second wavelength band for the transmission speed different from the first transmission speed so that it can be received in. The transmitting unit of the station side device can transmit the downlink signal using at least one wavelength, the uplink signal can be received by the receiving unit, and the reflected return light of the downlink signal is transmitted by the wavelength filter in the previous stage of the receiving unit. It includes a step of constructing a station-side device so that it can be attenuated, and a step of replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

The method for migrating a station-side device for an optical communication system according to one aspect of the present invention is a method for migrating a station-side device including an optical transceiver including a transmitter, and the method is for a first transmission speed. The step of configuring the station side device overlaps with at least a part of the receivable wavelength band of the receiving part so that the uplink signal having the wavelength included in the first wavelength band of the above can be received by the receiving part of the station side device. Moreover, the transmitting unit can transmit 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 the receiving unit can receive the uplink signal. In addition, the number of wavelengths used for the downlink signal is changed by exchanging the optical transceiver with the step of configuring the station side device so that the reflected return light of the downlink signal can be attenuated by the wavelength filter in the previous stage of the receiver. With steps.

FIG. 1 is a diagram showing 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 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 device shown in FIG. FIG. 5 is a diagram showing another configuration example of a station-side device 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 an example of studying one station-side device for coexistence of GE-PON, 10G-EPON, and 100G-EPON. FIG. 8 is a diagram showing another study example of a station-side device for coexistence of GE-PON, 10G-EPON, and 25G, 50G, and 100G-EPON. FIG. 9 is a diagram showing still another study example of a station-side device for coexistence of GE-PON, 10G-EPON, and 25G, 50G, and 100G-EPON. FIG. 10 is a diagram for explaining reception of an uplink signal by the station-side device shown in FIGS. 7 to 9. FIG. 11 is a diagram showing a configuration for solving the problem of an increase in branch loss in the configurations shown in FIGS. 7 to 9. FIG. 12 is a diagram showing an example of wavelength allocation of the uplink signal for each ODN in the configuration shown in FIG. FIG. 13 is a diagram for explaining a problem in the configuration of the station-side device shown in FIG. FIG. 14 is a diagram showing the relationship between the wavelength and the mask of the RMS spectrum width according to the upstream wavelength specification of 1000BASE-PX10, which is one of the standards of IEEE802.3. FIG. 15 is a schematic diagram illustrating a 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 mask of the RMS spectrum width according to the 1000BASE-PX20 (20 km) uplink wavelength specification, which is one of the IEEE802.3 standards. FIG. 17 is a schematic diagram illustrating the spectrum of the single longitudinal mode oscillation type DFB-LD. FIG. 18 is a diagram showing 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 downlink wavelength of 100 G. FIG. 20 is a diagram showing a schematic configuration of one example of a station-side device according to an embodiment of the present invention. FIG. 21 is a diagram illustrating an example of a migration scenario of the station side device. FIG. 22 is a schematic diagram illustrating an example of wavelength arrangement between the upstream wavelength of GE-PON and the reflected return light of the downlink signal of 100GE-EPON at the stage (Day 3) when 100G-EPON is mounted. FIG. 23 is a schematic configuration diagram of an optical communication system at the stage (Day 0) where GE-PON and 10G-EPON coexist. FIG. 24 is a schematic configuration diagram of an optical communication system at the 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 at the 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 at the 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 the 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 device according to the embodiment of the present invention.

[Issues to be resolved by this disclosure]
When introducing a new transmission capacity optical communication system, the arrangement of wavelengths between the optical communication system and the existing transmission capacity optical communication system may become a problem. For example, standardization of up wavelength and down wavelength of 100G-EPON is in progress. According to one proposal, the upstream and downstream wavelengths 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.
[Effect of this disclosure]
According to the above, even when the wavelength bands overlap between optical communications having different transmission capacities, those optical communications can coexist.

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

(1) In the method for migrating a station-side device for an optical communication system according to one aspect of the present invention, an uplink signal having a wavelength included in a first wavelength band for a first transmission rate is used as a station-side device. The step of configuring the station-side device and the second wavelength band for a transmission speed that overlaps at least a part of the first wavelength band and is different from the first transmission speed so that the reception unit can receive the signal. The transmitting unit of the station side device can transmit the downlink signal using at least one wavelength, the uplink signal can be received by the receiving unit, and the reflected return light of the downlink signal is the wavelength filter in the previous stage of the receiving unit. It is provided with a step of configuring a station-side device so that it can be attenuated by.

According to the above, even when the wavelength bands overlap between optical communications having different transmission capacities, those optical communications can coexist.

(2) Preferably, in 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, the transmission unit has one wavelength in the second wavelength band. And the step of configuring the station side device so that the downlink signal can be transmitted using the above, and configuring the station side device so that the transmitting unit can transmit the downlink signal using two or more wavelengths in the second wavelength band. Including steps.

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

(3) Preferably, in the migration method of the station side device, the transmitting unit can multiplex all of a plurality of predetermined wavelengths in the second wavelength band to transmit the downlink signal, and the receiving unit can transmit the uplink signal. The station-side device is further provided so that the reflected light can be received and the reflected return light can be attenuated by the wavelength filter.

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

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

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

(5) Preferably, the station side device includes an optical transceiver including at least a transmitter. The station-side device migration method further comprises the step of replacing the optical transceiver to change the number of wavelengths used in the downlink signal.

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

(6) The station-side device according to one aspect of the present invention includes a receiving unit configured to be able to receive an uplink signal having a wavelength included in the first wavelength band for the first transmission speed, and a first unit. A transmission unit configured to transmit a downlink signal using at least one wavelength that overlaps at least a part of the wavelength band and is included in the second wavelength band for a transmission speed different from the first transmission speed. It is provided in front of the receiving unit and includes a wavelength filter that attenuates the reflected return light returning to the receiving unit of the downlink signal.

According to the above, even when the wavelength bands overlap between optical communications having different transmission capacities, it is possible to realize a station-side device capable of coexisting those optical communications.

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

According to the above, even when the wavelength bands overlap between optical communications having different transmission capacities, it is possible to realize a station-side device capable of coexisting those optical communications.

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

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

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

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

(10) The transmission control method of the station-side device according to one aspect of the present invention receives an uplink signal having a wavelength included in the first wavelength band for the first transmission speed by the receiving unit of the station-side device. A downlink signal using at least one wavelength that overlaps at least a part of the first wavelength band and is included in the second wavelength band for a transmission speed different from the first transmission speed is transmitted to the station side device. It includes a step of transmitting by a transmitting unit and a step of attenuating the reflected return light of a downlink signal by a wavelength filter provided in front of the receiving unit.

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

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

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

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

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

(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.

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

(14) The optical communication system according to one aspect of the present invention is a first home-side device configured to transmit an uplink signal having a wavelength included in the first wavelength band for the first transmission rate. And, it is configured to be able to receive a downlink signal having at least one wavelength overlapping the first wavelength band and having at least one wavelength included in the second wavelength band for a transmission speed different from the first transmission speed. It includes 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 is provided in front of a receiving unit configured to receive an uplink signal, a transmitting unit configured to be able to transmit a downlink signal, and a receiving unit, and is a reflected return light returning to the receiving unit of the downlink signal. Includes a wavelength filter that attenuates the light.

According to the above, even when the wavelength bands overlap between optical communications having different transmission capacities, those optical communications can coexist.

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

According to the above, even when the wavelength bands overlap between optical communications having different transmission capacities, those optical communications can coexist.

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

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

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

According to the above, even when the transmission capacity of the optical communication using the second wavelength band increases, the optical communication using the first wavelength band and the optical communication using the second wavelength band can coexist. Can be done.

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

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

(19) Preferably, the first home-side device includes a single longitudinal mode distribution feedback type semiconductor laser as a light source for transmitting an uplink signal.

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

(20) In the migration method of the station-side device for the optical communication system according to one aspect of the present invention, the station-side device has an uplink signal having a wavelength included in the first wavelength band for the first transmission rate. Transmission of 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 and the step of configuring the station-side device so that it can be received by the receiving unit of The station side device is configured so that the unit can transmit the downlink signal, the receiver can receive the uplink signal, and the reflected return light of the downlink signal can be attenuated by the wavelength filter in the previous stage of the receiver. It comprises a step and a step of replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

According to the above, optical communication having different transmission capacities can coexist.
(21) The method for migrating a station-side device for an optical communication system according to one aspect of the present invention is a method for migrating a station-side device including an optical transceiver including a transmission unit, and the method is a first transmission. Because of the steps to configure the station side device and the transmission speed different from the first transmission speed so that the uplink signal having the wavelength included in the first wavelength band for speed can be received by the receiving part of the station side device. The transmitter can transmit a downlink signal using at least one wavelength included in the second wavelength band of the above, the uplink can be received by the receiver, and the reflected return light of the downlink is the reflected return light of the receiver. It includes a step of configuring a station-side device so that it can be attenuated by a wavelength filter in the previous stage, and a step of exchanging an optical transceiver to change the number of wavelengths used for a downlink signal.

According to the above, optical communication having different transmission capacities can coexist.
(22) In the method for migrating a station-side device for an optical communication system according to one aspect of the present invention, an uplink signal having a wavelength included in a first wavelength band for a first transmission rate is used as a station-side device. A second wavelength band for a transmission rate that overlaps at least a portion of the receivable wavelength band of the receiver and is different from the first transmission rate, so that it can be received by the receiver. The transmitting unit of the station-side device can transmit a downlink signal using at least one wavelength included in the above, the uplink signal can be received by the receiving unit, and the reflected return light of the downlink signal is in front of the receiving unit. It includes a step of constructing a station-side device so that it can be attenuated by a wavelength filter, and a step of replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength.

According to the above, optical communication having different transmission capacities can coexist.
(23) The method for migrating a station-side device for an optical communication system according to one aspect of the present invention is a method for migrating a station-side device including an optical transceiver including a transmission unit, and the method is a first transmission. A step of configuring the station side device and at least a part of the receivable wavelength band of the receiving part so that an uplink signal having a wavelength included in the first wavelength band for speed can be received by the receiving part of the station side device. The transmitting unit can transmit a downlink signal using at least one wavelength included in the second wavelength band for a transmission speed different from that of the first transmission speed, and the receiving unit can receive an uplink signal. The number of wavelengths used for the downlink signal by exchanging the optical transceiver with the step of configuring the station side device so that the reflected return light of the downlink signal can be attenuated by the wavelength filter in the previous stage of the receiver. Provide with steps to change.

According to the above, optical communication having different transmission capacities can coexist.
[Details of Embodiments of the present invention]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

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

FIG. 1 is a diagram showing a configuration example of an optical communication system according to an embodiment. In FIG. 1, the 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 the "home side device" can be realized by "OLT (Optical Line Thermal)" and "ONU (Optical Network Unit)".

The station-side device 301 is installed, for example, in the station building of a telecommunications carrier. The station-side device 301 mounts a host board (not shown). An optical transceiver (not shown) that mutually converts an electric signal and an optical signal is connected to the host board.

The home-side 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 line optical fiber 305 and at least one branch line optical fiber 306. The optical splitter 304 is connected to the trunk line optical fiber 305 and the branch line optical fiber 306. A plurality of home-side 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 the plurality of home side devices 302 by the optical splitter 304. On the other hand, the optical signal transmitted from each home-side device 302 is focused by the optical splitter 304 and sent to the station-side device 301 through the PON line 303. The optical splitter 304 passively splits or multiplexes a signal from an input signal without the need for external power supply.

As a high-speed PON system, a wavelength division multiplexing PON system in which a plurality of wavelengths are assigned to an uplink signal or a downlink signal and a plurality of wavelengths are wavelength-multiplexed to form an uplink signal or a downlink signal is being studied. For example, in a 100 Gbps class PON, four wavelengths of signals having a transmission capacity of 25 Gbps per wavelength can be assigned to each of the uplink and the downlink, and these can be wavelength-multiplexed. As an introduction scenario of such a wavelength division multiplexing PON system, a stepwise expansion (upgrade) of the transmission capacity can be considered.

For example, a scenario in which 25G-EPON or 50G-EPON is introduced prior to the introduction of 100GE-PON is assumed. In the drawings described below, "Day 1", "Day 2", "Day 3" and the like are notations of the stage of expansion of the 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 the stage, such as "first generation" or "second generation". Further, in the following description, "migration" means a system migration for expanding the transmission capacity. Further, since a system having a small transmission capacity has already become widespread, a system having a small transmission capacity and a system having a large transmission capacity may coexist. Hereinafter, embodiments 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 uplink (US) is 1260 to 1360 nm (1290-1330 nm in the Reduced specification), and the wavelength band assigned to the downlink (DS) is. It is 1480-1500 nm. In 10G-EPON, the wavelength band assigned to the uplink is 1260-1280 nm, and the wavelength band assigned to the downlink is 1575-1580 nm.

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

The up and down wavelength bands of 100G-EPON do not overlap with either the up or down wavelength bands of 10G-EPON. Therefore, 10G-EPON and 100G-EPON can coexist.

By increasing the number of wavelengths, expansion from 25G-EPON to 50G-EPON and 100G-EPON can be realized. Therefore, in the drawings described below, unless otherwise specified, a configuration for mounting 25G-EPON, which corresponds to a system in the previous stage of 100GE-PON, is shown.

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 device shown in FIG. With reference to FIGS. 3 and 4, the station-side device 301 includes an optical transceiver 141 and an electrical processing LSI 43.

The optical transceiver 141 supports 10 Gbps x 1 and 25 Gbps x 1 lanes. The optical transceiver 141 includes an optical wavelength division multiplexing (MUX / DMUX) 42, an electric processing LSI 43, optical transmission units 51 and 56, and optical reception units 61 and 66.

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

The optical transmission unit 56 (Tx0) receives an electric signal from the electric processing LSI 43 and converts the electric signal into an optical signal having a wavelength of λt0. The optical transmission unit 51 (Tx1) receives an electric signal from the electric processing LSI 43 and converts the electric signal into an optical signal having a wavelength of λt1. The optical signal having a wavelength of λt0 is a 10G downlink signal, and the optical signal having a wavelength λt1 is a 25G downlink signal.

The optical receiving unit 66 (Rx0) receives an optical signal having a wavelength of λr0 from the PON line 303 through the optical wavelength multiplexing separator 42, and converts the optical signal into an electric signal. The optical receiving unit 66 outputs the electric signal to the electric processing LSI 43. The optical receiving unit 61 (Rx1) receives an optical signal having a wavelength of λr1 from the PON line 303 through the optical wavelength multiplexing separator 42, and converts the optical signal into an electric signal. The optical receiving unit 61 outputs the electric signal to the electric processing LSI 43. The optical signal having a wavelength of λr0 is a 10G downlink signal, and the optical signal having a wavelength λr1 is a 25G downlink signal.

The electric processing LSI 43 performs various processing on the electric 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 electroprocessing LSI 43 can support multi-lane distribution control.

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

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

FIG. 5 is a diagram showing another configuration example of a station-side device 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. With reference to FIG. 5, the optical transceiver 141A differs from the optical transceiver 141 shown in FIG. 3 in that it includes an optical receiver 61A (Rx0 & Rx1) instead of the 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, an optical signal having a wavelength of λr0 and an optical signal having a wavelength of λr1 coexist in a PON line 303 by time division multiplexing (TDM). The optical receiving unit 61A receives a time-division-multiplexed optical signal having a wavelength λr0 and an optical signal having a wavelength λr1. The optical receiving unit 61A separates the received signal into a 10G uplink signal and a 25G uplink signal.

As shown in FIGS. 3 and 5, 10G-EPON and 100G-EPON can coexist by WDM in terms of downlink. Further, 10G-EPON and 100G-EPON can coexist by WDM or TDM in terms of uplink. However, as shown in FIG. 2, the upstream wavelength band and the downlink wavelength band of 100GE-PON overlap with the upstream wavelength band of GE-PON. Therefore, it is necessary to study the configuration of the station-side device in which GE-PON and 100G-EPON can coexist.

FIG. 7 is a diagram showing an example of studying one station-side device for coexistence of GE-PON, 10G-EPON, and 100G-EPON. In addition to the elements shown in FIG. 3, the optical transmission / reception unit 131 includes an optical transmission unit 21, an optical reception unit 31, and an optical wavelength division multiplexing separator 44. 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 division multiplexing separator 42 and the optical wavelength division multiplexing separator 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 an ODN (Optical Distribution Network) 31 to 314 via an optical splitter 308 (4 × 1 optical splitter).

The optical transmission unit 21 (Tx0') receives a downlink signal for 1G from the electric processing LSI 43, and transmits the downlink signal as an optical signal having a wavelength of λt0'. The optical receiving unit 31 (Rx0') receives an uplink signal from a home-side 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 downlink signal. Therefore, the receivable wavelength band of the optical receiving unit 31 includes the uplink (US) band (1260 nm-1360 nm) of the GE-PON. Since wavelengths of 25G, 50G, and 100G are included in the wide uplink wavelength band of GE-PON, when the optical transmission / reception unit 131 is composed of an optical transceiver for 1G and an optical transceiver for 25G / 50G / 100G. The optical splitter 307 is an indispensable component.

FIG. 8 is a diagram showing another study example of a station-side device for coexistence of GE-PON, 10G-EPON, and 25G, 50G, and 100G-EPON. In FIG. 8, in addition to the configuration shown in FIG. 3, the optical transmission / reception unit 131 includes an optical transmission unit 21, an optical reception unit 31, and an optical wavelength division multiplexing separator 44. The following description will not be repeated for the elements common to the elements shown in FIG. 7.

FIG. 9 is a diagram showing still another study example of a station-side device for coexistence of GE-PON, 10G-EPON, and 25G, 50G, and 100G-EPON. In FIG. 9, the optical transmission / reception unit 131 includes an optical reception unit 31A 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, a 10G downlink signal (wavelength λt0) from the optical transmission unit 56 is sent to the optical wavelength division multiplexing separator 44. Further, the optical receiver 66 is omitted.

FIG. 10 is a diagram for explaining reception of an uplink signal by the station-side device shown in FIGS. 7 to 9. As shown in FIG. 10, in the first example, the 1G uplink signal (wavelength λr0'), the 10G uplink signal (wavelength λr0), and the 25G uplink signal (wavelength λr1) are time-division-multiplexed. The electrical processing LSI 43 collectively manages the transmission timing of the uplink signal from each home-side device. Specifically, the electric processing LSI 43 gives each home-side device permission to transmit an uplink signal.

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

On the other hand, according to the configurations shown in FIGS. 7 to 9, it is considered that a branch loss of about 3 dB occurs in the optical splitter 307. In order to offset this branch loss, it is necessary to increase the power of the optical transmitting unit 21 and the sensitivity of the optical receiving unit 31.

FIG. 11 is a diagram showing a configuration for solving the problem of an increase in branch loss in the configurations shown in FIGS. 7 to 9. In the configuration shown in FIG. 11, the optical wavelength division multiplexing separator 42 and the optical wavelength division multiplexing separator 44 of the station side device 301 are connected to the optical splitter 309 (4 × 2 splitter) on the ODN. Therefore, the optical splitters 307 and 308 shown in FIG. 9 are integrated into the optical splitter 309. Similar to the optical splitter 307, when the optical transceiver 131 is composed of an optical transceiver for 1G and an optical transceiver for 25G / 50G / 100G, the optical splitter 309 is an indispensable component. ..

It is known that the branch loss due to the optical splitter 309 is similar to the branch 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, the branch loss due to the optical splitter 307 does not occur.

FIG. 12 is a diagram showing an example of wavelength allocation of the uplink signal for each ODN in the configuration shown in FIG. As shown in FIG. 12, since the time-division-multiplexed uplink signal is transmitted, the influence of the overlap between the 1G uplink wavelength band, the 10G uplink wavelength band, and the 100G uplink wavelength band can be reduced.

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 downlink signal is generated. The wavelength of this reflected return light is included in the wavelength band of the 1G uplink signal. Since the downlink signal is continuous light, the reflected return light of the downlink signal inevitably becomes an interfering wave.

In IEEE802.3, the level of optical return loss of ODN of GE-PON and 10G-EPON is defined as 20 dB min. Assuming that a maximum of + 10 dBm of 100 G-EPON downlink signal (4 wavelengths) per wave is attenuated by 26 dB due to the loss of the branch splitter (6 dB for round trip) + 20 dB of reflection at ODN, the reflected return light of 4 wavelengths of -16 dBm is generated. , Return to the station side device 301. This reflected return light passes through the wavelength division multiplexing separator 44 and enters the light receiving unit 31A.

The receiver for receiving the uplink signal of GE-PON needs to normally receive light of about -30 dBm. The optical receiver 31A must meet this specification. Considering the high sensitivity of the light receiving unit 31A as described above, the reflected return light is wavelength-filtered so that the intensity of the reflected return light of the 100G downlink signal becomes sufficiently small before being input to the light receiving unit 31A. It is necessary to attenuate with.

For example, a filter that attenuates a 100G downlink signal by about 30 dB is arranged in the front stage of the optical receiver 31A or the front stage of the optical wavelength division multiplexing separator 44. With this filter, the input of the reflected return light of the 100G downlink signal to the 1G receiver (optical receiver 31A) is -46 dBm (= -16-30) per wave, and the total of the four waves is -40 dBm. The attenuated reflected return light is sufficiently smaller than the 1G uplink signal received by the light receiving unit 31A.

However, the up wavelength of GE-PON (1260-1360 nm) and the down wavelength of 100G-EPON (4 wavelengths exist at 1335-1360 nm) are in the same wavelength region. Although it is possible to attenuate the reflected return light of the 100G downlink signal by the wavelength filter, there is a problem that the reflected return light and the 1G uplink signal cannot be separated by the wavelength division multiplexing separator 44.

IEEE802.3, which is a standard for GE-PON, assumes that a multi-longitudinal mode oscillation type optical transmitter such as FP-LD (Fabry-Perot type semiconductor laser) is used as an uplink transmitter. In the case of a multi-longitudinal mode oscillation type optical transmitter, the RMS (root mean square) spectrum width has a large influence on the transmission characteristics. Therefore, in the multi-longitudinal mode oscillation type optical transmitter, the RMS spectrum width is required to be narrower as the oscillation wavelength of the transmitter deviates 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 mask of the RMS spectrum width according to the upstream wavelength specification of 1000BASE-PX10, which is one of the standards of IEEE802.3. FIG. 15 is a schematic diagram illustrating a spectrum of an FP-LD (Fabry-Perot type semiconductor laser) light source for 1000BASE-PX10.

FP-LD is generally used for the multi-longitudinal mode oscillation type optical transmitter. 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. Generally, in FP-LD, the temperature change of the center wavelength is large. In the example shown in FIG. 15, the temperature change of the center wavelength of the FP-LD is about 40 nm. Therefore, the uplink 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 mask of the RMS spectrum width according to the 1000BASE-PX20 (20 km) uplink wavelength specification, which is one of the IEEE802.3 standards. As shown in FIG. 16, in 1000BASE-PX20, the width of the allowable RMS spectrum is smaller than that in 1000BASE-PX10. With FP-LD, it is difficult to satisfy the mask specification of 1000BASE-PX20. In order to satisfy the mask specification of 1000BASE-PX20, an uplink transmitter using a single longitudinal mode oscillation type DFB-LD (distributed feedback type semiconductor laser) element is generally used.

FIG. 17 is a schematic diagram illustrating the spectrum of the single longitudinal mode oscillation type DFB-LD. As shown in FIG. 17, the single longitudinal mode oscillation type DFB-LD has a feature that the RMS spectrum width is smaller and the temperature change of the center wavelength is smaller than that of the FP-LD. For example, in the example shown in FIG. 17, the temperature change of the center wavelength of the DFB-LD is about 7 nm. The DFB-LD can achieve an upstream wavelength in the band 1290 nm-1330 nm, which is sufficiently narrower than the IEEE 1260 nm-1360 nm specification.

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

FIG. 18 is a diagram showing an example of an actual specification range of an uplink transmitter applied to GE-PON (1000BASE-PX10). The specification range of the center wavelength for satisfying the transmission wavelength mask defined by IEEE802.3 is 1260 to 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-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 downlink wavelength of 100 G. FIG. 20 is a diagram showing a schematic configuration of one example of a station-side device according to an embodiment of the present invention. With reference to FIGS. 19 and 20, station side device 301 includes optical transceivers 151A, 151B. The optical transceiver 151A is an optical transceiver for 25G / 50G / 100G-EPON, and includes an optical wavelength division multiplexing separator 42, an optical transmission unit 51 (Tx1), and an optical reception unit 61 (Rx1). The optical transceiver 151B is an optical transceiver for 1G and 10G, and includes an optical wavelength division multiplexing separator 44, an optical transmission unit 21 (Tx0'), and an optical reception unit 31A (Rx0). The following description will not be repeated for the same elements as those shown in FIG.

A wavelength filter 71 for attenuating the reflected return light having a downlink wavelength of 100 G is arranged in front of the optical wavelength division multiplexing separator 44. The wavelength filter 71 has a characteristic of attenuating light having an upstream wavelength of 1357 nm or more and 1360 nm or less while passing light having an upstream wavelength of 1353 nm or less and light having a downlink wavelength of 1490 nm to 1580 nm. As a result, the wavelength filter 71 receives the reflected return light of one wavelength (λt1) of the 100G downlink signal while receiving the uplink signal of 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-mentioned pass band, the reflected return light of the signal having the wavelengths λt2, λt3 and λt4 among the 100G downlink signals cannot be cut by the wavelength filter 71. Therefore, in this embodiment, the wavelength filter is replaced with the migration of the station-side device 301 to cut the reflected return light of the signal having the wavelengths λt2, λt3, and λt4. As the stage progresses from Day 0 to Day 3, the number of wavelengths used for the 100G downlink signal increases, so that the wavelength band of the 100G downlink signal expands 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 100G downlink signal in such a case.

FIG. 21 is a diagram illustrating an example of a migration scenario of the station side device. With reference to FIGS. 20 and 21, GE-PON (1000BASE-PX10), GE-PON (1000BASE-PX20), and 10G-EPON are implemented at the Day0 stage. That is, GE-PON and 10G-EPON coexist. At this stage, it is not necessary to provide the station side device with a wavelength filter for cutting the reflected return light of the 100G downlink signal.

At the Day 1 stage, 25G-EPON is implemented, and GE-PON, 10G-EPON and 25G-EPON coexist. 50G-EPON and 100G-EPON have not been introduced or are inactive. At this stage, in order to cut the reflected return light of the 25G downlink signal, light having an uplink wavelength of 1353 nm or less and light having a downlink wavelength of 1490 nm to 1580 nm are passed, while light having an uplink wavelength of 1357 nm or more and 1360 nm or less is attenuated. A wavelength filter to be used is provided on the receiving side of the 1G uplink signal of the station side device (previous stage of the optical wavelength multiplexing separator 44).

At the Day 2 stage, 50G-EPON is implemented, and GE-PON, 10G-EPON, 25G-EPON and 50G-EPON coexist. 100G-EPON has not been introduced or is inactive. In the scenario shown in FIG. 21, the GE-PON (1000BASE-PX10) compliant home-side device is upgraded to the 10G-EPON home-side device at the Day 2 stage.

The wavelength arrangement of the downlink signal at 50G-EPON is 1359 ± 1 nm and 1349 ± 1 nm. In order to cut the reflected return light of the 25G-EPON and 50G-EPON downlink signals, the wavelength filter used in the Day 1 step is replaced with a wavelength filter having a shorter cutoff wavelength. Specifically, the wavelength filter 71 that attenuates the light having an uplink wavelength of 1335 nm or more and 1360 nm or less while passing the light having an uplink wavelength of 1330 nm or less and the light having a downlink wavelength of 1490 nm to 1580 nm is a 1G uplink signal of the station side device. It is provided on the receiving side (previous stage of the optical wavelength division multiplexing separator 44). In the Day 2 stage, the transmitter of the station side device 301 uses more wavelengths (wavelengths λd1 and λd2 shown in FIG. 21) included in the downlink wavelength band of 100G-EPON as compared with the Day 1 stage. To send. In this embodiment, the wavelength filter used in the stage of Day 1 is not only the reflected return light of the 25G downlink signal (downlink of wavelength λd1) in the stage of Day 1, but also the additional downlink signal (downlink of wavelength λd2). Replace with a wavelength filter with a shorter cutoff wavelength to attenuate the reflected return light of the signal).

At the stage of Day 3, 100G-EPON is implemented, and GE-PON, 10G-EPON, 25G-EPON, 50G-EPON and 100G-EPON coexist. The wavelength arrangement of the downlink signal at 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 downlink signals of 25G-EPON, 50G-EPON and 100G-EPON, while passing light with an uplink wavelength of 1330 nm or less and light with a downlink wavelength of 1490 nm to 1580 nm, it is 1335 nm or more and 1360 nm or less. A wavelength filter 71 for attenuating the light of the upstream wavelength of the above is provided on the receiving side of the 1G upstream signal of the station side device (previous stage of the optical wavelength multiplexing separator 44).

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

FIG. 23 is a schematic configuration diagram of an optical communication system at the stage (Day 0) where GE-PON and 10G-EPON coexist. The optical transceiver 151, the electric processing LSIs 2A and 2B, and the uplink band allocation control LSI 3 are mounted on the host board 1A. The optical transceiver 151 can support both 1 Gbps (wavelength λ0') and 10 Gbps (wavelength λ0) transmission capacities.

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

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

Each of the electric processing LSIs 2A and 2B is configured to be able to communicate with the outside of the host board 1A. Upstream band allocation control The 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 the stage (Day 1) in which GE-PON, 10G-EPON and 25G-EPON coexist. At the stage of Day 1, the home-side device 302 corresponding to 25 Gbps is introduced into the optical communication system. The host board 1A may be replaced with the host board 1B. The optical transceiver 161, the electric processing LSIs 2, 2A, and 2B, and the uplink band allocation control LSI 3 are mounted on the host board 1B.

The optical transceiver 161 can support 1 Gbps (wavelength λ0'), 10 Gbps (wavelength λ0) and 25 Gbps (wavelength λ1). Multiple optical transceivers that support a single or multiple wavelengths may be used in place of the optical transceiver 161.

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

FIG. 25 is a schematic configuration diagram of an optical communication system at the stage (Day 2) in which GE-PON, 10G-EPON, 25G-EPON and 50G-EPON coexist. The home-side device 302 corresponding to 50 Gbps is introduced into the optical communication system. At the Day 2 stage, the optical transceiver 161 (see FIG. 24) is replaced with an 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 (wavelength λ1, λ2). Multiple optical transceivers that support a single or multiple wavelengths may be used in place of the optical transceiver 171.

FIG. 26 is a schematic configuration diagram of an optical communication system configuration at the stage (Day 3) in which 10G-EPON, 25G-EPON, 50G-EPON and 100G-EPON coexist. At the Day 3 stage, the optical transceiver 171 (see FIG. 25) is replaced with an 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 (wavelength λ1, λ2, λ3, λ4). Multiple optical transceivers that support a single or multiple wavelengths may be used in place 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-side device is connected to each of the ODNs 31 to 314 via an optical splitter. In FIG. 27, home-side devices 302a, 302b, 302c, and 302d connected to ODN311 via an optical splitter 315 (4 × 1 optical splitter) are typically shown.

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 the GE-PON uplink signal (wavelength of 1260-1360 nm) and the GE-PON downlink signal (wavelength of 1480-1500 nm).

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

The home-side device 302b is a home-side device compliant with GE-PON (1000BASE-PX20), and includes a WDM filter 81b, an optical transmission unit 82b, and an optical reception unit 83b. Like the WDM filter 81a, the WDM filter 81b is a filter for separating the GE-PON uplink signal (wavelength of 1260-1360 nm) and the GE-PON downlink 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 an uplink signal of 10G-EPON (wavelength of 1260-1280 nm) and a downlink signal of 10G-EPON (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 optical receiver 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 the upstream signal of 25G-EPON (wavelength of 1287-1290 nm) and the downlink signal of 25G-EPON (wavelength of 1357-1360 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.

The uplink signals transmitted from each of the home-side devices 302a to 302d are reflected by the ODN311. The reflected return light (attenuated by 20 dB or more) of the uplink signal 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 ODN) having a transmission speed different from the transmission speed of the home-side device is input to each home-side device as interfering light.

On the receiving side of the home-side device 302a, the WDM filter 81a can cut the reflected return light from the ODN311 of the 25G downlink signal and the 25G uplink signal. On the transmitting side of the home-side device 302a, the reflected return light from the ODN311 of the 25G downlink signal and the 25G uplink signal is incident. Generally, the reflected return light resistance of the FP-LD transmitter is strong. Due to the reflected return light resistance of the semiconductor laser 84a, the influence of the return light on the semiconductor laser 84a can be reduced even 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 reflected return light from the ODN311 of the 25G downlink signal and the 25G uplink signal. On the transmitting side of each of the home-side devices 302b and 302c, the isolators (85b and 85c) can cut the reflected return light from the ODN311 of the 25G downlink signal and the 25G uplink signal.

A 1G downlink signal and a 10G downlink signal are input to the home-side device 302d. These downlink signals are cut by the WDM filter 81d. Therefore, it is possible to avoid the influence of the 1G downlink signal and the 10G downlink signal on both the receiving side and the transmitting side of the home-side device 302d.

The reflected return light from each ODN311 of the 1G uplink signal and the 10G uplink signal is input to the home side device 302d. On the receiving side of the home-side device 302d, the reflected return light can be cut by the WDM filter 81d. On the transmitting side of the home-side device 302d, the reflected return light can be cut by the isolator 85d. Therefore, it is possible to avoid the influence of the reflected return light from the ODN311 of the 1G uplink signal and the 10G uplink signal on both the receiving side and the transmitting side of the home-side device 302d.

The station side device 301 includes optical transceivers 151A and 151B. The optical transceiver 151A includes optical transmission units 51 and 56 and optical reception units 61. The optical transmission unit 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 transmitting unit 21 and an optical receiving unit 32. The optical transmission unit 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 light receiving unit 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 as the light source. For each of the optical transmitters 51, 56, 21, the isolators (51b, 56b, 21b) transmit the reflected return light of the uplink signal and the downlink signal from the station side device 301 to the semiconductor laser (51a, 56a, 21a). It is possible to prevent input.

The optical wavelength division multiplexing separator 42 passes only the 25G uplink signal out of the input optical signal and the input reflected return light to the optical receiving unit 61. Further, the uplink signals from the home-side devices 302a to 302d are time-division-multiplexed. Therefore, it is possible to prevent the reception of the 25G uplink signal by the optical receiving unit 61 from being affected by the uplink signal of another transmission speed and the reflected return light.

A wavelength filter 71 is provided in front of the optical wavelength division multiplexing separator 44. The wavelength filter 71 cuts the reflected return light of the 25G downlink signal. The optical wavelength multiplexing separator 44 passes only the uplink light signal through the optical receiver 32 among the uplink light signal, the reflected return light of the 1G downlink signal, and the reflected return light of the 10G downlink signal input from the ODN side. Further, the uplink signals from the home-side devices 302a to 302d are time-division-multiplexed. Therefore, it is possible to prevent the reception of the 1G uplink signal and the 10G uplink signal by the optical receiving unit 32 from being affected by the 25G uplink signal and the reflected return light of the downlink signal from the station side device 301.

Embodiments of the present invention are not limited to being feasible only in the case of the wavelength arrangement shown in FIG. FIG. 28 is a schematic diagram for explaining another example of the wavelength arrangement of GE-PON, 10G-EPON, and 100G-EPON. For the uplink of 100GE-PON, 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 uplink wavelength band of 10G-EPON. Placed on a band. In this respect, the wavelength arrangement shown in FIG. 28 is different from the wavelength arrangement shown in FIG. However, embodiments of the present invention can also be applied in the case of the wavelength arrangement shown in FIG. 28.

Further, 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. With reference to FIG. 29, 10G-EPON has not been introduced in Day 0. In this respect, the scenario shown in FIG. 29 differs 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 device according to the embodiment of the present invention. As shown in FIG. 30, the optical transmission / reception unit 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 division multiplexing separator 42, an optical transmission unit 51, an optical transmission unit 56, and an optical reception unit 61. The optical transceiver 151D is a 1G optical transceiver, and includes an optical wavelength division multiplexing separator 44, an optical transmission unit 21, and an optical reception unit 31.

In the optical transceiver 151A, an optical transmission unit 56 for transmitting a 10G downlink signal (wavelength λt0) and an optical transmission unit 51 for transmitting a 25G downlink signal (wavelength λt0) are coupled to an optical wavelength division multiplexing separator 42. To. The optical receiving unit 61 can receive an uplink signal at a dual rate of 25 Gbps and 10 Gbps.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims rather than the above-described embodiment, and is intended to include meaning 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 band 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 fiber multiplexing separator, 71 wavelength filter, 81a, 81b, 81c, 81d WDM filter, 131 optical transmitter / receiver, 141, 141A, 151, 151A, 151B, 151C, 151D, 161, 171, 181 optical transceiver, 300 PON system, 301 station side device, 302, 302a, 302b, 302c, 302d home side device, 303 PON line, 304, 307, 308, 309, 315 optical splitter, 305 trunk optical fiber, 306 branch optical Fiber, 310 fiber optic transmission line.

Claims (23)

A migration method for station-side equipment for optical communication systems.
A step of configuring the station-side device so that an uplink 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 that overlaps at least a portion of the first wavelength band and is included in the second wavelength band for a transmission rate different from the first transmission rate. The station-side device so that a downlink 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 a wavelength filter in the previous stage of the receiving unit. A method of migrating station-side equipment, including steps to configure. The step of configuring the station-side device so that the transmitter of the station-side device can transmit the downlink signal using at least one wavelength is a step.
A step of configuring the station-side device so that the transmitter can transmit the downlink signal using one wavelength in the second wavelength band.
The station-side device according to claim 1, further comprising a step of configuring the station-side device so that the transmission unit can transmit the downlink signal using two or more wavelengths within the second wavelength band. Migration method. The transmitting unit can multiplex all of a plurality of predetermined wavelengths in the second wavelength band to transmit the downlink signal, the receiving unit can receive the uplink signal, and the above-mentioned The method for migrating a station-side device according to claim 1 or 2, further comprising a step of forming the station-side device so that the reflected return light can be attenuated by the wavelength filter. The method for migrating a station-side device 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. The station-side device includes an optical transceiver that includes at least the transmitter.
The method for migrating a station-side device according to any one of claims 1 to 4, further comprising a step of exchanging the optical transceiver to change the number of wavelengths used for the downlink signal. A receiver configured to be able to receive an uplink signal having a wavelength included in the first wavelength band for the first transmission rate, and a receiver.
A configuration capable of transmitting a downlink signal using at least one wavelength that overlaps at least a part of the first wavelength band and is included in the second wavelength band for a transmission speed different from the first transmission speed. With the transmitter
A station-side device provided in front of the receiving unit and provided with a wavelength filter for attenuating the reflected return light of the downlink signal returning to the receiving unit. The station-side device according to claim 6, wherein the transmission unit is configured to be capable of transmitting the downlink signal using one wavelength in the second wavelength band. The station-side device according to claim 6 or 7, wherein the transmission unit is configured to be capable of transmitting the downlink signal using two or more wavelengths within the second wavelength band. Any one of claims 6 to 8, wherein the transmission unit is configured to multiplex all of a plurality of predetermined wavelengths in the second wavelength band so that the downlink signal can be transmitted. Station-side device as described in the section. A step of receiving an uplink signal having a wavelength included in the first wavelength band for the first transmission speed by the receiving unit of the station side device, and
A downlink signal using at least one wavelength that overlaps at least a part of the first wavelength band and is included in the second wavelength band for a transmission speed different from the first transmission speed is transmitted to the station side device. Steps to be transmitted by the transmitter and
A transmission control method for a station-side device, comprising a step of attenuating the reflected return light of the downlink signal by a wavelength filter provided in front of the receiving unit. The transmission control method for a station-side device according to claim 10, wherein the transmission step includes a step in which the transmission unit transmits the downlink signal using one wavelength in the second wavelength band. The transmission control of the station-side device according to claim 10 or 11, wherein the transmission step includes a step in which the transmission unit transmits the downlink signal using a plurality of wavelengths in the second wavelength band. Method. Any of claims 10 to 12, wherein 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 the downlink signal. The transmission control method for the station-side device according to item 1. A first home-side device configured to transmit an uplink signal having a wavelength included in the first wavelength band for the first transmission rate.
A downlink signal having at least one wavelength overlapping the first wavelength band and having at least one wavelength included in the second wavelength band for a transmission speed different from the first transmission speed is configured to be receivable. The second home-side device and
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 is provided, and the station-side device is
A receiver configured to receive the uplink signal and
A transmitter configured to transmit the downlink signal and
An optical communication system including a wavelength filter provided in front of the receiving unit and attenuating the reflected return light of the downlink signal returning to the receiving unit. The optical communication system according to claim 14, wherein the transmission unit is configured to be capable of transmitting the downlink signal using one wavelength in the second wavelength band. The optical communication system according to claim 14 or 15, wherein the transmission unit is configured to be capable of transmitting the downlink signal using two or more wavelengths within the second wavelength band. Any one of claims 14 to 16, wherein the transmission unit is configured to multiplex all of a plurality of predetermined wavelengths in the second wavelength band so that the downlink signal can be transmitted. The optical communication system according to the section. The optical communication system according to any one of claims 14 to 17, wherein the first home-side device includes a Fabry-Perot type semiconductor laser as a light source for transmitting the uplink signal. The optical communication system according to any one of claims 14 to 17, wherein the first home-side device includes a single longitudinal mode distribution feedback type semiconductor laser as a light source for transmitting the uplink signal. .. A migration method for station-side equipment for optical communication systems.
A step of configuring the station-side device so that an uplink 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 the second wavelength band for a transmission speed different from the first transmission speed, and the reception unit can transmit the uplink signal. A step of configuring the station-side device so that the signal can be received and the reflected return light of the downlink signal can be attenuated by the wavelength filter in the previous stage of the receiving unit.
A method of migrating station-side equipment, comprising replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength. A method of migrating a station-side device for an optical communication system, wherein the station-side device includes an optical transceiver including a transmitter.
A step of configuring the station-side device so that an uplink 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 transmitting unit can transmit 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 the receiving unit can receive the uplink signal. And the step of configuring the station-side device so that the reflected return light of the downlink signal can be attenuated by the wavelength filter in the previous stage of the receiving unit.
A method of migrating a station-side device comprising replacing the optical transceiver and changing the number of wavelengths used in the downlink signal. A migration method for station-side equipment for optical communication systems.
A step of configuring the station-side device so that an uplink 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 by the station-side device using at least one wavelength that overlaps at least a portion of the receivable wavelength band of the receiver and is included in the second wavelength band for a transmission rate different from the first transmission rate. The station so that the unit can transmit a downlink signal, the receiver unit can receive the uplink signal, and the reflected return light of the downlink signal can be attenuated by the wavelength filter in the previous stage of the receiver unit. The steps that make up the side device and
A method of migrating station-side equipment, comprising replacing the wavelength filter with a wavelength filter having a shorter cutoff wavelength. A method of migrating a station-side device for an optical communication system, wherein the station-side device includes an optical transceiver including a transmitter.
A step of configuring the station-side device so that an uplink 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 uses at least one wavelength that overlaps at least a part of the receivable wavelength band of the receiver and is 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 receiver can receive the uplink signal and the reflected return light of the downlink signal can be attenuated by the wavelength filter in the previous stage of the receiver. Steps to do and
A method of migrating a station-side device comprising replacing the optical transceiver and changing the number of wavelengths used in the downlink signal.

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