JP5247482B2 - Main station side device, sub station side device, central station and optical communication system - Google Patents

Description

  The present invention relates to a station side device (OLT) in an optical communication system in which an optical fiber is shared among a plurality of subscribers, such as GE-PON (Gigabit Ethernet-Passive Optical Network) (Ethernet is a registered trademark / hereinafter abbreviated). : Optical Line Terminal) The present invention relates to a main station side device, a sub station side device, a central station, and an optical communication system that can use devices of a plurality of providers.

  With the rapid spread of broadband lines in recent years, there is an increasing expectation for FTTH (Fiber To The Home) in order to provide economical and stable high-speed communication. As one form of this FTTH service, a PON (Passive Optical Network) system in which one optical fiber is shared by a plurality of users is known.

This system includes an OLT installed in a central office, an ONU (Optical Network Unit) installed in a subscriber's house, a star coupler, and an optical fiber. There are several types of PON systems, for example, the GE-PON system described in Non-Patent Document 1 below.
In such a PON system, a single optical fiber connected to the OLT can efficiently accommodate a large number of subscribers. In order to take advantage of this advantage, a star coupler is actually often configured to branch a few times at the central office and then branch again near the subscriber's home.

IEEE 802.3-2005 (registered trademark)

  Since the conventional optical communication system is configured as described above, a telecommunications carrier having an optical fiber network may be obliged to lend (unbundle) the optical fiber to another telecommunications carrier due to laws and regulations. . In this case, conventionally, it is necessary to lend one of the branches in the central office to each downstream star coupler, or to share the OLT or lower and separate the operators by the upper switch.

  However, in the case of the former, even when the borrower's telecommunications carrier provides service to one subscriber, all of the number of branches (for example, four units) will be borrowed, and the borrowing cost will increase. There are challenges. In the latter case, since only one OLT can be installed on the PON system, each carrier cannot differentiate services that require changing the function of the OLT. Furthermore, there was a problem that the OLT could not be stopped or changed due to the circumstances of one telecommunications carrier, resulting in a management obstacle.

  The present invention has been made to solve the above-described problems, and allows a plurality of station side devices to be used, and different telecommunications carriers use their own station side devices to provide services. The main station side device, sub station side device, central station, and optical communication system can be rented out to a telecommunications carrier in units of one optical fiber, and can be easily managed with little influence on each other's services. For the purpose.

An optical communication system according to the present invention includes a plurality of lights provided to belong to any one of the first to n-th station-side devices and any one of the first to n-th station-side devices. Downstream optical signals of the same wavelength that are connected via a fiber optic between the line terminator, the first to nth station side devices and the plurality of optical line terminators, and transmitted from the first to nth station side devices Combining and distributing to a plurality of optical line terminators, combining upstream optical signals of the same wavelength transmitted from the plurality of optical line terminators and distributing to the first to n-th station side devices; The first station side device sets the uplink transmission time of the optical line termination device belonging to the local station side device and transmits it to the optical fiber, and sets the uplink transmission possible time of the other station side device set except the transmission time, the downlink transmission available time of another station side apparatus Set, the downstream optical signals to the downlink transmission time, excluding the downlink transmittable time set and transmitted via the optical fiber, the optical line terminal of the n-th uplink transmittable time set by the first station apparatus The upstream transmission time of the optical line termination device belonging to the local station side device is set based on the transmission time and transmitted to the optical fiber, and the downstream transmission time is determined based on the downstream transmission available time set by the first station side device. And the downstream optical signal is transmitted via the optical fiber at the downstream transmission time, and the plurality of optical line terminators are connected to the combining / distributing means and the first to n-th station side received via the optical fiber. The upstream optical signal is transmitted via the optical fiber at the upstream transmission time set by any of the devices.

  According to the present invention, a combination of a plurality of logical station-side devices and optical line terminators can be accommodated in one physical optical communication system, so that an optical fiber can be lent in one branch unit. . Therefore, a communication carrier that borrows an optical fiber can reduce the optical fiber borrowing cost. In addition, since the station side devices can be changed and stopped independently of each other, there is an effect that the management independence can be enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the PON system by Embodiment 1 of this invention. It is a block diagram which shows the detail of OLT and ONU by Embodiment 1 of this invention. It is a timing chart which shows the transmission process of OLT and ONU by Embodiment 1 of this invention. It is a block diagram which shows the detail of OLT and ONU by Embodiment 2 of this invention. It is a timing chart which shows the transmission process of OLT and ONU by Embodiment 2 of this invention. It is a block diagram which shows the detail of OLT and ONU by Embodiment 3 of this invention. It is a timing chart which shows the transmission process of OLT and ONU by Embodiment 3 of this invention. It is a block diagram which shows the detail of OLT and ONU by Embodiment 4 of this invention. It is a timing chart which shows the transmission process of OLT and ONU by Embodiment 4 of this invention. It is a block diagram which shows the PON system by Embodiment 5 of this invention. It is a block diagram which shows the detail of OLT and ONU by Embodiment 5 of this invention. It is a block diagram which shows the PON system by Embodiment 6 of this invention.

An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a PON system according to Embodiment 1 of the present invention. In the figure, this PON system (optical communication system) combines and distributes an optical fiber 2 and an optical fiber 2 to a central station 1. Subscriber homes 5 to 7 are connected through star couplers (combining and distributing means) 3 and 4.

  In the central office 1, for example, a main OLT (main station side device, first station side device) 11 installed by the communication carrier A is connected to the upper network 21 of the communication carrier A, and the communication carrier B The secondary OLT (secondary station side device, second station side device) 12 installed by is connected to the upper network 22 of the communication carrier B.

  Furthermore, an ONU (optical line termination unit) 31 belonging to the subordinate of the main OLT 11 is connected to the user terminal 41 at the subscriber home 5, and an ONU (optical line terminator) belonging to the subordinate of the main OLT 11 at the subscriber home 6. 32 is connected to the user terminal 42, and the ONU (optical line terminating unit) 33 belonging to the sub OLT 12 is connected to the user terminal 43 in the subscriber house 7.

  In FIG. 1, only three subscriber homes 5 to 7 are shown, but in reality, they may be connected to more subscriber homes and belong to the sub OLT 12. The subscriber's home may be connected not only to the subscriber home 7 but also to many more subscriber homes.

  FIG. 2 is a configuration diagram showing details of the OLT and ONU according to the first embodiment of the present invention. In the figure, details of the main OLT 11, the sub OLT 12, the ONU 31 belonging to the main OLT 11, and the ONU 33 belonging to the sub OLT 12 are shown. The configuration is shown.

  In the main OLT 11, the higher-order interface 11a adds the identification number (identifier) of the transmission destination ONU to the downstream frame input from the higher-level network, and also transmits the ONU of the transmission source added to the input upstream frame. Whether or not the identification number corresponds to the identification number of an ONU subordinate to the main OLT 11 is checked, and if it matches, the upstream frame is transferred to the upper network, and if it does not match, the upstream frame is discarded. The identification numbers of ONUs belonging to the main OLT 11 are those stored in advance in the higher-level interface 11a.

  The PON clock 11b generates time. The gate frame generator 11c is called a gate frame in which the upstream transmission time of an ONU belonging to the main OLT 11 is set based on the time generated from the PON clock 11b and the identification number of the transmission destination ONU is added. In addition to generating a control frame, the uplink transmittable time of the secondary OLT 12 is set excluding the set uplink transmission time, and a gate frame to which the identification number of the secondary OLT 12 of the transmission destination is added is generated.

  The combiner 11d combines the downstream frame and the gate frame. The optical transmitter 11e converts the downstream frame and gate frame of the electrical signal into an optical signal having a wavelength λ1 and transmits the optical signal.

  The wavelength demultiplexing filter 11f enables input / output of optical signals of wavelength λ1 and wavelength λ from the two optical fiber sides, respectively, and optical signals of wavelength λ1 and wavelength λ respectively input from the two optical fiber sides. Multiplexing enables output to one optical fiber side, enables separation of optical signals of wavelength λ1 and wavelength λ input from one optical fiber side, and enables output to two optical fiber sides It is what.

  The optical receiver 11g converts the upstream frame of the received optical signal having the wavelength λ into an electrical signal. The distributor 11h distributes the upstream frame to the higher-order interface 11a and the gate frame generator 11c.

  In the secondary OLT 12, the higher-order interface 12a adds the identification number of the transmission destination ONU to the downlink frame input from the higher-level network, and the identification number of the transmission source ONU added to the input uplink frame. Whether the ID corresponds to the identification number of an ONU belonging to the sub OLT 12 is checked, and if it matches, the upstream frame is transferred to the upper network, and if it does not match, the upstream frame is discarded. Note that the identification numbers of the ONUs belonging to the sub OLT 12 are those stored in advance in the higher-level interface 12a.

  The PON clock 12b generates time synchronized with the PON clock 11b. The gate frame decoding generator 12c checks whether the transmission destination identification number added to the gate frame output from the optical receiver 12j, which will be described later, corresponds to the identification number of the sub-OLT 12, and if it matches, Based on the frame uplink transmittable time and the time generated from the PON clock 12b, the uplink transmission time of the ONU belonging to the sub OLT 12 is set, and the gate frame to which the identification number of the transmission destination ONU is added Is to be generated.

  The combiner 12d combines the downstream frame and the gate frame. The optical transmitter 12e converts the downstream frame and gate frame of the electrical signal into an optical signal having a wavelength λ2 and transmits the optical signal.

  The wavelength demultiplexing filter 12f enables input / output of optical signals of wavelength λ2 and wavelength λ from the two optical fiber sides, respectively, and optical signals of wavelength λ2 and wavelength λ input from the two optical fiber sides, respectively. Multiplexing enables output to one optical fiber side, enables separation of optical signals of wavelength λ2 and wavelength λ input from one optical fiber side, and enables output to two optical fiber sides It is what.

  The optical receiver 12g converts the upstream frame of the received optical signal having the wavelength λ into an electrical signal. The distributor 12h distributes the upstream frame to the higher-order interface 12a and the gate frame decoding generator 12c. The wavelength demultiplexing filter 12i can input only the optical signal having the wavelength λ1 among the input optical signals. The optical receiver 12j converts the received gate frame of the optical signal having the wavelength λ1 into an electrical signal and outputs it to the gate frame decoding generator 12c.

  In the ONU 31, the wavelength demultiplexing filter 31a enables input / output of optical signals having wavelengths λ1 and λ from the two optical fiber sides, respectively, and allows the wavelength λ1 and wavelength λ respectively input from the two optical fibers. Multiplexing optical signals enables output to one optical fiber side, separates optical signals of wavelength λ1 and wavelength λ input from one optical fiber side, and outputs to two optical fiber sides Is made possible.

  The optical receiver 31b converts the downstream frame and gate frame of the received optical signal having the wavelength λ1 into an electrical signal. The distributor 31c distributes the downstream frame and the gate frame. The user-side interface 31d checks whether the transmission destination ONU identification number added to the input downlink frame corresponds to the identification number of the ONU, and if it matches, forwards the downlink frame to the user terminal. In this case, the downstream frame is discarded, and the identification number of the ONU is added to the upstream frame input from the user terminal.

  The PON clock 31e generates time synchronized with the PON clocks 11b and 12b. The gate frame decoder 31f checks whether or not the transmission destination identification number added to the gate frame distributed from the distributor 31c corresponds to the identification number of the ONU. A read timing signal is output based on the time generated from the PON clock 31e.

  The upstream queue 31g stores upstream frames from the user-side interface 31d, and reads the stored upstream frames in accordance with the read timing signal output from the gate frame decoder 31f. The optical transmitter 31h converts the upstream frame of the electrical signal into an optical signal having a wavelength λ and transmits it.

  In the ONU 33, the wavelength demultiplexing filter 33a enables input / output of optical signals of wavelength λ2 and wavelength λ from the two optical fibers, respectively, and allows input of wavelengths λ2 and λ respectively input from the two optical fibers. Multiplexing optical signals enables output to one optical fiber side, separates optical signals of wavelength λ2 and wavelength λ input from one optical fiber side, and outputs to two optical fiber sides Is made possible.

  The optical receiver 33b converts the downstream frame and gate frame of the received optical signal having the wavelength λ2 into an electrical signal. The distributor 33c distributes the downstream frame and the gate frame. The user-side interface 33d checks whether the transmission destination ONU identification number added to the input downlink frame corresponds to the identification number of the ONU, and if it matches, forwards the downlink frame to the user terminal. In this case, the downstream frame is discarded, and the identification number of the ONU is added to the upstream frame input from the user terminal.

  The PON clock 33e generates time synchronized with the PON clocks 11b, 12b, 31e. The gate frame decoder 33f checks whether the identification number of the transmission destination added to the gate frame distributed from the distributor 33c corresponds to the identification number of the ONU, and if it matches, the uplink transmission time of the gate frame The read timing signal is output based on the time generated from the PON clock 33e.

  The upstream queue 33g stores upstream frames from the user-side interface 33d and reads the stored upstream frames in accordance with the read timing signal output from the gate frame decoder 33f. The optical transmitter 33h converts the upstream frame of the electrical signal into an optical signal having a wavelength λ and transmits it.

Next, the operation will be described.
In FIG. 1, it is assumed that the data flow from the central office 1 to the subscriber houses 5 to 7 is down, and the data flow from the subscriber homes 5 to 7 is the upstream.

  As the flow of the downlink data, the downstream frame input from the upper network 21 in the central office 1 is converted into a downstream optical signal having the wavelength λ1 by the main OLT 11, and the downstream frame input from the upper network 22 is converted to the wavelength by the sub OLT 12. The optical signal is converted into a downstream optical signal of λ2 and transmitted to the subscriber houses 5 to 7 via the optical fiber 2 and the star couplers 3 and 4, respectively.

  As an upstream data flow, an upstream frame input from the user terminal 41 in the subscriber home 5 is converted into an upstream optical signal having a wavelength λ by the ONU 31, and an upstream frame input from the user terminal 42 in the subscriber home 6 is used. Is converted into an upstream optical signal of wavelength λ by the ONU 32, and further, an upstream frame input from the user terminal 43 in the subscriber's house 7 is converted into an upstream optical signal of wavelength λ by the ONU 33, and the optical fiber 2 and the star coupler 4 are respectively converted. , 3 to the central office 1.

  Thus, in the PON system according to the first embodiment, downstream optical signals having different wavelengths λ1 and λ2 are transmitted from the main OLT 11 and the sub OLT 12, and upstream optical signals having the same wavelength λ are transmitted from the ONUs 31 to 33. It is what is done.

  Here, in downstream and upstream communications, the wavelengths λ1 and λ2 of the downstream optical signal are different from the wavelength λ of the upstream optical signal, so even if the single optical fiber 2 is provided between the star couplers 3 and 4. Bidirectional communication can be performed without interference. Also in downstream communication, the wavelengths of downstream optical signals are λ1 and λ2, which are different from each other. Therefore, communication is performed without interference even if the star couplers 3 and 4 are a single optical fiber 2. be able to.

  However, in the upstream communication, the wavelength of the upstream optical signal is λ and is the same. Therefore, as will be described later, by setting the transmission time of the upstream optical signal from each ONU, the star couplers 3 and 4 Even if there is a single optical fiber 2 between them, communication is performed without interference.

  FIG. 2 shows a detailed configuration of only the main OLT 11, the sub OLT 12, the ONU 31 belonging to the subordinate of the main OLT 11, and the ONU 33 belonging to the subordinate OLT 12, but the main OLT 11 and the sub OLT 12 have In addition, although there are ONUs belonging to the subordinate, they are omitted.

  The main OLT 11 has a PON clock 11b, the sub OLT 12 has a PON clock 12b, the ONU 31 has a PON clock 31e, and the ONU 33 has a PON clock 33e. The main OLT 11 is connected to the sub OLT 12 and each ONU. The time is set at the same time, and it is always synchronized while connected.

  Further, each OLT and each ONU is set with a unique identification number. Since the specific method of exchange at the time of connection varies depending on the standard, it will not be mentioned. In the following description, it is assumed that the time synchronization and the identification number have been set.

Hereinafter, referring to FIG. 2, the flow of the downstream optical signal from the main OLT 11 and the sub OLT 12 to each ONU will be described.
In the main OLT 11, an identification number of a transmission destination ONU (for example, ONUs 31 and 32 (ONU 32 is not shown)) is added to the downstream frame input from the upper network 21 on the right side to the upper interface 11a. This is converted into an optical signal of wavelength λ1 by the optical transmitter 11e through the combiner 11d and transmitted to the optical fiber 2 through the wavelength demultiplexing filter 11f.

  Similarly, in the secondary OLT 12, the identification number of the transmission destination ONU (for example, ONUs 33 and 34 (ONU 34 is not shown)) is added to the downstream frame input from the upper network 22 on the right side to the upper interface 12a. . This is converted into an optical signal of wavelength λ2 by the optical transmitter 12e through the combiner 12d and transmitted to the optical fiber 2 through the wavelength demultiplexing filter 12f.

  The downstream optical signal having the wavelength λ1 transmitted from the main OLT 11 and the downstream optical signal having the wavelength λ2 transmitted from the sub OLT 12 are combined by the star coupler 3 and transmitted by one optical fiber 2, and further, An optical signal distributed by the coupler 4 and combined with a downstream optical signal having a wavelength λ1 and a downstream optical signal having a wavelength λ2 is transmitted to all OLTs.

  For example, taking the ONU 31 as an example, the wavelength demultiplexing filter 31a separates and inputs only the downstream optical signal having the wavelength λ1 from the downstream optical signals having the wavelengths λ1 and λ2. The input downstream optical signal having the wavelength λ1 is converted into an electric signal by the optical receiver 31b and input to the user side interface 31d via the distributor 31c.

In the user side interface 31d, the identification number of the transmission destination ONU added to the input downlink frame is compared with the identification number of the own ONU, and if they match, the downlink frame is transferred to the user terminal 41 side. Discard if they do not match.
Similarly, the ONU 32 compares the identification number of the transmission destination ONU added to the downlink frame with the identification number of the own ONU, and accepts the downlink frame.

  Similarly, in the ONU 33, the wavelength demultiplexing filter 33a separates and inputs only the downstream optical signal having the wavelength λ2 from the received downstream optical signals having the wavelengths λ1 and λ2. The input downstream optical signal having the wavelength λ2 is converted into an electric signal by the optical receiver 33b and input to the user side interface 33d via the distributor 33c.

In the user side interface 33d, the identification number of the transmission destination ONU added to the input downlink frame is compared with the identification number of the own ONU, and if they match, the downlink frame is transferred to the user terminal 43 side. Discard if they do not match.
Similarly, the ONU 34 compares the identification number of the transmission destination ONU added to the downlink frame with the identification number of the own ONU, and accepts the downlink frame.
In this way, the downstream optical signal is transmitted from the main OLT 11 and the sub OLT 12 to a plurality or one desired ONU belonging to the subordinate.

Next, referring to FIG. 2, the flow of the upstream optical signal from each ONU to the main OLT 11 and the sub OLT 12 will be described.
As described above, if upstream optical signals are transmitted simultaneously from a plurality of ONUs, the signals are collided and mixed by the star coupler 4 and cannot be distinguished on the OLT side.

Therefore, the gate frame generator 11c in the main OLT 11 uses the time of the PON clock 11b to calculate the transmittable times shifted from each other so that the optical signals from the respective ONUs do not collide.
First, the gate frame generator 11c individually sets transmission times at which upstream optical signals can be transmitted to ONUs (ONUs 31 and 32) belonging to its own OLT (main OLT 11), and adds the identification numbers of the ONUs 31 and 32. Generated gate frame.

  FIG. 3 is a timing chart showing OLT and ONU transmission processing according to the first embodiment of the present invention. As shown in FIG. 3A, a gate frame at the transmission time to the ONUs 31 and 32 is generated.

  Next, the gate frame generator 11c sets the transmission time that can be assigned to the other OLT (secondary OLT 12) as the transmission time, and generates a gate frame to which the identification number of the second OLT 12 is added.

  As shown in FIG. 3 (2), this transmission possible time is set to a time excluding the transmission time to the ONUs 31 and 32 set as described above, and is later turned on by the gate frame generator 12c in the secondary OLT 12. , 34 can be set as a transmission time at which the upstream optical signal can be transmitted. The gate frame generated by the gate frame generator 11c is converted into an optical signal having a wavelength λ1 and transmitted by the optical transmitter 11e, distributed by the star coupler 4 and transmitted to all ONUs, but also distributed to the secondary OLT 12 Is done.

  In the sub OLT 12, only the optical signal having the wavelength λ1 is input by the wavelength demultiplexing filter 12i, converted into an electrical signal by the optical receiver 12j, and input to the gate frame decoding generator 12c. As shown in FIG. 3 (3), the gate frame decoding generator 12 c transmits the upstream optical signal to the ONUs (ONUs 33 and 34) belonging to its own OLT (secondary OLT 12) within the range of transmission time by the gate frame. A transmission time that can be transmitted is individually set, and a gate frame to which the identification numbers of the ONUs 33 and 34 are added is generated. The gate frame generated by the gate frame generator 12c is converted into an optical signal having a wavelength λ2 by the optical transmitter 12e and transmitted, distributed by the star coupler 4, and transmitted to all ONUs.

  In the ONUs 31 and 32, for example, when the ONU 31 is taken as an example, only the downstream optical signal having the wavelength λ1 is input to the wavelength demultiplexing filter 31a, converted into an electrical signal by the optical receiver 31b, and converted through the distributor 31c. The gate frame is output to the gate frame decoder 31f. The gate frame decoder 31f decodes the received gate frame and stores a transmission time corresponding to the identification number of the own ONU (ONU 31) added to the gate frame.

Further, the upstream frame input from the left user terminal (user terminal 41) to the ONU 31 is added with the identification number of the ONU 31 to identify the transmission source, and is temporarily stored in the upstream queue 31g. The gate frame decoder 31f outputs a read timing signal to the upstream queue 31g when the stored transmission time is reached, and the upstream frame read from the upstream queue 31g is converted into an optical signal of wavelength λ by the optical transmitter 31h. Sent.
Similarly, the ONU 32 transmits an upstream frame as an optical signal having a wavelength λ at a transmission time corresponding to the identification number of the ONU 32.
An upstream frame transmitted from the ONUs 31 and 32 is shown in FIG.

  In the ONUs 33 and 34, for example, taking the ONU 33 as an example, in the wavelength demultiplexing filter 33a, only the downstream optical signal of wavelength λ2 is input, converted into an electrical signal by the optical receiver 33b, and converted through the distributor 33c. The gate frame is output to the gate frame decoder 33f. The gate frame decoder 33f decodes the received gate frame and stores the transmission time corresponding to the identification number of the own ONU (ONU 33) added to the gate frame.

Further, the upstream frame input to the ONU 33 from the user terminal (user terminal 43) on the left side is added with the identification number of the ONU 33 to identify the transmission source, and is temporarily stored in the upstream queue 33g. The gate frame decoder 33f outputs a read timing signal to the upstream queue 33g when the stored transmission time is reached, and the upstream frame read from the upstream queue 33g is converted into an optical signal of wavelength λ by the optical transmitter 33h. Sent.
Similarly, the ONU 34 transmits an upstream frame as an optical signal having a wavelength λ at a transmission time corresponding to the identification number of the ONU 34.
An upstream frame transmitted from the ONUs 33 and 34 is shown in FIG.

The optical signals transmitted from the ONUs 31 to 34 are distributed to the main OLT 11 and the sub OLT 12 via the optical fiber 2 and the star couplers 3 and 4.
At this time, the ONUs 31 and 32 transmit at the transmission time set by the gate frame generator 11c of the main OLT 11, and the ONUs 33 and 34 at the transmittable time excluding the transmission time set by the gate frame generator 11c of the main OLT 11. Therefore, the transmission is performed at the transmission time set by the gate frame decoding generator 12c of the secondary OLT 12. Therefore, the upstream optical signal can be communicated without the upstream optical signal colliding on one optical fiber 2.

  In the wavelength demultiplexing filter 11f in the main OLT 11, only the optical signal of wavelength λ received from the optical fiber 2 is input, and in the optical receiver 11g, the upstream frame of the received optical signal of wavelength λ is converted into an electrical signal. . In the upper interface 11a, it is determined whether the identification number of the ONU added to the upstream frame input via the distributor 11h corresponds to the identification number of the ONU belonging to the own OLT (main OLT 11). The upstream frame is transferred to the upper network 21, and discarded if not equivalent.

  In the gate frame generator 11c, when an upstream frame input via the distributor 11h is received within a transmission time set in advance in the gate frame generator 11c, the upstream frame is transmitted to the upper network 21. You may make it forward.

  In the wavelength demultiplexing filter 12f in the sub OLT 12, only the optical signal having the wavelength λ received from the optical fiber 2 is input, and the optical receiver 12g converts the upstream frame of the received optical signal having the wavelength λ into an electrical signal. . The upper interface 12a determines whether the identification number of the ONU added to the upstream frame input via the distributor 12h corresponds to the identification number of the ONU belonging to the own OLT (secondary OLT 12). The upstream frame is transferred to the upper network 22 and, if not, discarded.

In the gate frame decryption generator 12c, when the upstream frame input via the distributor 12h is received within the transmission time set in advance in the gate frame decryption generator 12c, the upstream frame is converted into the upper network. You may make it forward to 22.
In this way, an upstream optical signal is transmitted from each ONU to a desired main OLT 11 and sub OLT 12 that control the own ONU.

  As described above, according to the first embodiment, in the PON system including one or more ONUs belonging to the main OLT 11, the sub OLT 12 is provided in addition to the main OLT 11, and one or more units belonging to the sub OLT 12 are also subordinate. Since, for example, when the main OLT 11 is installed by the communication carrier A and the secondary OLT 12 is installed by the communication carrier B, the communication operator A to the communication operator A can be accommodated in one PON system. The optical fiber can be lent to B in one branch unit. Therefore, there is an effect that the communication carrier B that borrows the optical fiber can reduce the optical fiber borrowing cost.

  In this case, the secondary OLT 12 installed by the communication carrier B is completely independent of the main OLT 11 installed by the communication carrier A with respect to the downlink signal, and the transmission possible time set in the main OLT 11 with respect to the uplink signal as well. Since the transmission time of the ONU belonging to the subordinate can be set freely, the control of the main OLT 11 and the sub OLT 12 can be changed independently of each other. There is an effect of increasing independence.

  Furthermore, even if the secondary OLT 12 stops without permission from the main OLT 11, there is no effect on the main OLT 11 side. Therefore, the secondary OLT 12 can be stopped independently from the main OLT 11 and communicated. There exists an effect which can raise the independence of the management of the provider B.

  Further, as long as the signal from the main OLT 11 to the sub OLT 12 is negotiated, the downstream signal has a different wavelength and is independent, and the upstream signal also has only the designation of time, so that the communication carrier A and the communication carrier B Even if the communication method and the transmission speed are different, there is an effect that they can be mixed.

  Further, if the communication carrier A installs the secondary OLT 12, there is an effect that a plurality of services (such as different transmission speeds) can be provided on one PON system.

  Further, since the downstream optical signals transmitted from the main OLT 11 and the secondary OLT 12 have different wavelengths, the transmission time of the downstream optical signals transmitted from the main OLT 11 and the secondary OLT 12 is not set for the downstream optical signals. However, it is possible to avoid reception failure due to signal collision.

  Furthermore, by transmitting the uplink transmittable time from the main OLT 11 to the sub OLT 12 via the optical fiber 2 as an optical signal, it is possible to transmit each transmittable time without adding a configuration such as an electric signal line. There is.

  Further, the ONU or OLT of the transmission destination and the transmission source is represented by an identification number, and the ONU or OLT determines only the transmission information addressed to the own device by determining whether the transmission information is addressed to the own device by collating the identification number. There is an effect that can be reliably received.

Embodiment 2. FIG.
FIG. 4 is a block diagram showing details of the OLT and ONU according to the second embodiment of the present invention. In the figure, the gate frame decoding generator 12k is a function of the gate frame decoding generator 12c shown in the first embodiment. In addition, if a gate frame is not output from the optical receiver 12j even after a predetermined time set in advance, it is determined that the main OLT 11 is out of order, and an upstream transmission possible time is set instead of the main OLT 11. Is.
Since other configurations are the same as those in the first embodiment, a duplicate description is omitted.

Next, the operation will be described.
In the second embodiment, the secondary OLT 12 can detect the failure of the main OLT 11, and when the failure is detected, the upstream OLT 12 can set the transmission time of the upstream transmission of the secondary OLT 11.
When the main OLT 11 breaks down or when the main OLT 11 is intentionally stopped due to the circumstances of the communication carrier A, a downstream optical signal having the wavelength λ1 is not transmitted from the main OLT 11. Therefore, the downstream optical signal having the wavelength λ1 from the main OLT 11 is not received by the optical receiver 12j of the sub OLT 12 as well.

  The gate frame decoding generator 12k determines that the main OLT 11 is out of order when no gate frame is output from the optical receiver 12j even after a predetermined time has passed, and can perform uplink transmission on behalf of the main OLT 11 Set the time.

FIG. 5 is a timing chart showing transmission processing of the OLT and ONU according to the second embodiment of the present invention. When it is determined that the main OLT 11 is in failure, the gate frame decoding generator 12k of the sub OLT 12 As shown in 1), the transmission time at which the upstream optical signal can be transmitted to the ONUs (ONUs 33 and 34) belonging to the own OLT (sub-OLT 12), assuming that all times are the upstream transmission possible time of the secondary OLT 12 Are individually set, and a gate frame to which the identification numbers of the ONUs 33 and 34 are added is generated.
The following operation is the same as that in the first embodiment, and the ONUs 33 and 34 transmit the upstream optical signal based on the received transmission time as shown in FIG.

  Further, when the main OLT 11 is restored and the gate frame is output to the gate frame decoding generator 12k through the optical receiver 12j of the sub OLT 12, it is determined that the main OLT 11 has been restored, and the sub OLT 12 The setting proxy is stopped, and the transmission time of the upstream optical signal is set based on the upstream transmission available time from the main OLT 11.

  As described above, according to the second embodiment, when a failure of the main OLT 11 is detected in the secondary OLT 12, the uplink transmission available time is set instead of the main OLT 11, and therefore, even if the main OLT 11 is stopped, the sub OLT 12 or lower Thus, the main OLT 11 and the secondary OLT 12 can perform setting change and stop due to a failure independently of each other, and further, the management independence can be improved.

Embodiment 3 FIG.
FIG. 6 is a block diagram showing the details of the OLT and ONU according to the third embodiment of the present invention. In the figure, the gate frame decoding generator 12l has the function of the gate frame decoding generator 12c shown in the first embodiment. In addition, if a gate frame is not output from the optical receiver 12j even after a predetermined time has passed, it is determined that the main OLT 11 has failed, and the sub OLT 12 and the sub OLT 13 are connected in place of the main OLT 11. This is for setting the transmission possible time.

  When the gate frame decoding generator 12l determines that the failure of the main OLT 11, it sets the upstream transmission time of the ONU belonging to the sub OLT 12 based on the time generated from the PON clock 11b, Generates a gate frame to which the identification number of the ONU of the transmission destination is added, sets the uplink transmittable time of the secondary OLT 13 excluding the set uplink transmission time, and adds the identification number of the transmission destination secondary OLT 13 The generated gate frame is generated. The optical transmitter 12m converts the gate frame to which the identification number of the sub-OLT 13 of the electrical signal is added into an optical signal having the wavelength λ1 and transmits the optical signal.

  In FIG. 6, the sub-OLT (third station side device) 13, the higher-order side interface 13a, the PON clock 13b, the gate frame decoding generator 13c, the combiner 13d, the optical transmitter 13e, the wavelength demultiplexing filter 13f, and the optical receiver 13g, the divider 13h, the wavelength multiplexing / demultiplexing filter 13i, and the optical receiver 13j are the same as those in the sub-OLT 12 described in the second embodiment, but the gate frame decoding generator 13c in FIG. If the gate frame is not output from the optical receiver 13j even after the set predetermined time, it is determined that the main OLT 11 and the sub OLT 12 are out of order, and the uplink transmittable time is set instead of the main OLT 11 and the sub OLT 12 To do. The optical transmitter 13e converts the downstream frame of the electrical signal into an optical signal having a wavelength λ3 and transmits the optical signal.

In FIG. 6, the wavelength multiplexing / demultiplexing filter 35a, the optical receiver 35b, the distributor 35c, the user-side interface 35d, the PON clock 35e, the gate frame decoder 35f, the upstream queue 35g, and the optical transmitter 35h are arranged in the ONU 35. 6 is the same as the configuration in the ONU 31 and ONU 33 described in the first embodiment, but the wavelength demultiplexing filter 12f in FIG. 6 receives optical signals of wavelengths λ3 and λ from the two optical fibers. Enables output, multiplexes optical signals of wavelength λ3 and wavelength λ respectively input from two optical fiber sides, enables output to one optical fiber side, and inputs from one optical fiber side The optical signals having the wavelengths λ3 and λ are separated and output to the two optical fibers is possible.
Since other configurations are the same as those in the first embodiment, a duplicate description is omitted.

Next, the operation will be described.
In the third embodiment, in the configuration described in the first embodiment, the OLT has three configurations (main OLT 11, sub OLT 12, and sub OLT 13), and, as described in the second embodiment, In the secondary OLT 12, the failure detection of the main OLT 11 is enabled, and when the failure is detected, the upstream OLT 12 and the secondary OLT 13 are set to be capable of uplink transmission instead of the main OLT 11, and the secondary OLT 13 Failure detection is enabled, and when a failure is detected, the upstream OLT 13 and the secondary OLT 12 can be set in place of the primary OLT 11 and the secondary OLT 12.

FIG. 7 is a timing chart showing OLT and ONU transmission processing according to Embodiment 3 of the present invention.
In FIG. 6, in addition to the operation of the first embodiment, the gate frame generator 11c sets a transmission time that can be assigned to another OLT (secondary OLT 13) as a transmission available time, and adds an identification number of the second OLT 13 Generated gate frame.
As shown in FIG. 7 (1), this transmittable time is set to a time excluding the transmit time to the ONUs 31 and 32 and the transmittable time to the secondary OLT 12.

In the sub OLT 13, only the optical signal having the wavelength λ1 is input by the wavelength demultiplexing filter 13i, converted into an electrical signal by the optical receiver 13j, and input to the gate frame decoding generator 13c. As shown in FIG. 7 (2), the gate frame decoding generator 13c can transmit an upstream optical signal to an ONU (ONU 35) belonging to its own OLT (secondary OLT 13) within a range of transmission time by the gate frame. A transmission frame is set, and a gate frame to which the ONU 35 identification number is added is generated.
The gate frame generated by the gate frame generator 13c is converted into an optical signal having a wavelength λ3 by the optical transmitter 13e and transmitted, distributed by the star coupler 4, and transmitted to all ONUs.

  In the ONU 35, only the downstream optical signal having the wavelength λ3 is input by the wavelength demultiplexing filter 35a, converted into an electrical signal by the optical receiver 35b, and the converted gate frame is output to the gate frame decoder 35f via the distributor 35c. To do. The gate frame decoder 35f decodes the received gate frame and stores a transmission time corresponding to the identification number of the own ONU (ONU 35) added to the gate frame.

Further, the upstream frame input to the ONU 35 from the left user terminal is added with the identification number of the ONU 35 for identifying the transmission source, and is temporarily stored in the upstream queue 35g.
The gate frame decoder 35f outputs a read timing signal to the upstream queue 35g when the stored transmission time is reached, and the upstream frame read from the upstream queue 35g is converted into an optical signal of wavelength λ by the optical transmitter 35h. Sent.
An upstream frame transmitted from the ONU 35 is shown in FIG.

Optical signals transmitted from the ONUs 31 to 35 are distributed to the main OLT 11, the sub OLT 12 and the sub OLT 13 via the optical fiber 2 and the star couplers 3 and 4.
In the wavelength demultiplexing filter 13f in the sub OLT 13, only the optical signal having the wavelength λ received from the optical fiber 2 is input, and in the optical receiver 13g, the upstream frame of the received optical signal having the wavelength λ is converted into an electrical signal. . In the higher-order interface 13a, it is determined whether the identification number of the ONU added to the upstream frame input via the distributor 13h corresponds to the identification number of the ONU belonging to the own OLT (secondary OLT 13). The upstream frame is transferred to the higher level network, and discarded if it does not correspond.
In this way, an upstream optical signal is transmitted from each ONU to a desired sub-OLT 13 that controls the own ONU.

  When the main OLT 11 breaks down or when the main OLT 11 is intentionally stopped due to the circumstances of the communication carrier A, a downstream optical signal having the wavelength λ1 is not transmitted from the main OLT 11. Therefore, the downstream optical signal having the wavelength λ1 from the main OLT 11 is not received by the optical receiver 12j of the sub OLT 12 as well.

The gate frame decoding generator 12l determines that the main OLT 11 is out of order when no gate frame is output from the optical receiver 12j even after a predetermined time, and can perform uplink transmission on behalf of the main OLT 11. Set the time.
When it is determined that the main OLT 11 is in failure, the gate frame decoding generator 12l of the secondary OLT 12 regards all times as upstream transmission possible times of the secondary OLT 12, and selects ONUs belonging to its own OLT (secondary OLT 12). The transmission time at which the upstream optical signal can be transmitted is individually set for the ONUs 33 and 34), and a gate frame to which the identification numbers of the ONUs 33 and 34 are added is generated.

  Further, as shown in FIG. 7 (4), the gate frame decoding generator 12l of the secondary OLT 12 sets the upstream transmission available time of the secondary OLT 13 except for the upstream transmission times of the ONUs 33 and 34 set as described above, and transmits the transmission. A gate frame to which the identification number of the previous secondary OLT 13 is added is generated. The optical transmitter 12m converts the gate frame to which the identification number of the sub-OLT 13 of the electrical signal is added into an optical signal having the wavelength λ1 and transmits the optical signal.

In the secondary OLT 13, since the gate frame is input as usual in the gate frame decoding generator 13c, the gate frame decoding generator 13c generates the gate frame for the ONU 35 as usual as shown in FIG. 7 (5). .
Hereinafter, as shown in FIG. 7 (6), the ONU 35 transmits the upstream optical signal based on the received transmission time.

  Further, when the sub OLT 12 fails or when the sub OLT 12 is intentionally stopped due to the circumstances of the carrier B, the downstream optical signal having the wavelength λ1 is not transmitted from the sub OLT 12. Therefore, the optical receiver 13j of the secondary OLT 13 does not receive the downstream optical signal having the wavelength λ1 from the main OLT 11 and the secondary OLT 12.

  When the gate frame is not output from the optical receiver 13j even after a predetermined time set in advance, the gate frame decoding generator 13c determines that the main OLT 11 and the sub OLT 12 are faulty, and the main OLT 11 and the sub OLT 12 Instead of this, the uplink transmittable time is set.

When it is determined that the primary OLT 11 and the secondary OLT 12 are faulty, as shown in FIG. 7 (7), the gate frame decoding generator 13c of the secondary OLT 13 regards all times as being the uplink transmittable time of the secondary OLT 13. Thus, a transmission time at which the upstream optical signal can be transmitted is set for the ONUs 35 belonging to the sub-OLT 13 and a gate frame to which the identification number of the ONU 35 is added is generated.
Hereinafter, as shown in FIG. 7 (8), the ONU 35 transmits the upstream optical signal based on the received transmission time.

  Further, when the main OLT 11 is restored and a gate frame is output to the gate frame decoding generator 12k through the optical receiver 12j of the sub OLT 12, it is determined that the main OLT 11 has been restored, and the sub OLT 12 The transmission time of the upstream optical signal is set based on the transmittable time.

  Further, when the gate frame is output to the gate frame decryption generator 13c through the optical receiver 13j of the secondary OLT 13, it is determined that the primary OLT 11 has been restored, and the secondary OLT 13 stops the setting of the upstream transmission available time, The transmission time of the upstream optical signal is set based on the upstream transmission possible time from the main OLT 11.

  As described above, according to the third embodiment, in the PON system including one or more ONUs belonging to the main OLT 11, the sub OLTs 12 and 13 are provided in addition to the main OLT 11 and are also subordinate to the sub OLTs 12 and 13. Since one or more ONUs can be provided and these can be accommodated in one PON system, for example, the main OLT 11 is installed by the communication carrier A, the sub OLT 12 is installed by the communication carrier B, and the sub OLT 13 is set by the communication carrier. When C is installed, it is possible to lend optical fibers from the communication carrier A to the communication carrier B and lend optical fibers from the communication carrier A to the communication carrier C in one branch unit. Therefore, there is an effect that the communication carriers B and C that borrow an optical fiber can reduce the optical fiber borrowing cost.

  In addition, since three or more OLTs can be connected on one PON system and the control of the main OLT 11 and the sub OLTs 12 and 13 can be changed independently of each other, the management of the carriers A, B, and C can be performed. There is an effect of increasing independence.

  Further, the main OLT 11 and the sub OLTs 12 and 13 can perform setting change and stop due to a failure independently of each other, and further, the management independence can be enhanced.

Embodiment 4 FIG.
FIG. 8 is a block diagram showing details of the OLT and ONU according to the fourth embodiment of the present invention. In FIG. 8, the downstream queue 11i in the main OLT 11 stores downstream frames from the higher-order interface 11a, and a gate frame generator In response to the read timing signal output from 11j, the accumulated downstream frames are read.

  In addition to the function of the gate frame generator 11c described in the first embodiment, the gate frame generator 11j sets the downlink transmittable time of the secondary OLT 12, and adds the identification number of the transmission destination secondary OLT 12 A gate frame is generated. Further, the gate frame generator 11j temporarily stores the set downlink transmission available time, and sends the readout timing signal to the downlink queue 11i so that the downlink frame is read out at the downlink transmission time excluding the set downlink transmission available time. Output.

  In the secondary OLT 12, the downstream queue 12n stores downstream frames from the higher-order interface 12a, and reads the stored downstream frames in accordance with a readout timing signal output from the gate frame decoding generator 12o.

  In addition to the function of the gate frame decryption generator 12c shown in the first embodiment, the gate frame decryption generator 12o has a transmission destination identification number added to the gate frame output from the optical receiver 12j. If it matches the identification number of the OLT 12, and if they match, the downlink transmittable time of the gate frame is temporarily stored, and the read timing signal is downloaded so that the downlink frame is read at the set downlink transmittable time. The data is output to the queue 12n.

  The optical transmitter 12p converts the downstream frame and gate frame of the electrical signal into an optical signal having a wavelength λ1 and transmits the optical signal. The wavelength demultiplexing filter 12q enables input / output of optical signals of wavelength λ1 and wavelength λ from the two optical fiber sides, respectively, and optical signals of wavelength λ1 and wavelength λ input from the two optical fiber sides, respectively. Multiplexing enables output to one optical fiber side, enables separation of optical signals of wavelength λ1 and wavelength λ input from one optical fiber side, and enables output to two optical fiber sides It is what.

In the ONU 33, the wavelength demultiplexing filter 33i enables input and output of optical signals of wavelength λ1 and wavelength λ from the two optical fibers, respectively, and allows input of wavelengths λ1 and λ respectively input from the two optical fibers. Multiplexing optical signals enables output to one optical fiber side, separates optical signals of wavelength λ1 and wavelength λ input from one optical fiber side, and outputs to two optical fiber sides Is made possible.
Since other configurations are the same as those in the first embodiment, a duplicate description is omitted.

Next, the operation will be described.
In the fourth embodiment, in the configuration described in the first embodiment, the wavelength of the downstream optical signal from the main OLT 11 and the sub OLT 12 is set to λ1 = λ2.
Here, in the upstream communication, the wavelength of the upstream optical signal is λ, which is the same. Therefore, by setting the transmission time of the upstream optical signal from each ONU as described above, the star coupler 3, The communication between the four optical fibers 2 is performed without interference even in the case of the single optical fiber 2, but in the downstream communication, the wavelength of the downstream optical signal is λ1 and is the same. By setting the transmission time of the downstream optical signal from the OLT 11 and the sub OLT 12, even if the single optical fiber 2 is used between the star couplers 3 and 4, communication is performed without interference.

FIG. 9 is a timing chart showing OLT and ONU transmission processing according to Embodiment 4 of the present invention.
In FIG. 8, downstream frames from the higher-order interface 11a are stored in the downstream queue 11i in the main OLT 11. As shown in FIG. 9A, the gate frame generator 11j sets the downlink transmittable time of the secondary OLT 12, and generates a gate frame to which the identification number of the transmission destination secondary OLT 12 is added. Further, as shown in FIG. 9 (2), the gate frame generator 11j temporarily stores the set downlink transmittable time, and reads the downlink frame at the downlink transmit time excluding the set downlink transmittable time. In addition, the read timing signal is output to the downstream queue 11i. Note that the gate frame generator 11j can independently set the downlink transmission time within the downlink transmission available time range other than the downlink transmission available time set in the sub-OLT 12.

  The downlink queue 11i reads the accumulated downlink frame in accordance with the read timing signal output from the gate frame generator 11j. The gate frame generated by the gate frame generator 11j and the downlink frame read from the downlink queue 11i are converted into an optical signal having the wavelength λ1 and transmitted by the optical transmitter 11e, distributed by the star coupler 4 and all the ONUs. Is also distributed to the secondary OLT 12.

In the wavelength demultiplexing filter 12i in the sub OLT 12, only the optical signal of the wavelength λ1 is input, converted into an electrical signal by the optical receiver 12j, and input to the gate frame decoding generator 12o. Further, the downstream queue 12n stores downstream frames from the higher-order interface 12a.
As shown in FIG. 9 (3), the gate frame decoding generator 12o outputs a read timing signal to the downlink queue 12n so that the downlink frame is read at the downlink transmission time within the range of the downlink transmission available time by the gate frame. To do. Note that the gate frame decoding generator 12o can independently set the downlink transmission time as long as it is within the downlink transmission available time range set in the sub-OLT 12.

  The downstream queue 12n reads the stored downstream frame in accordance with the readout timing signal output from the gate frame decoding generator 12o. Downstream optical signals of wavelength λ1 from the main OLT 11 and the sub OLT 12 are combined by the optical fiber 2 and the star couplers 3 and 4, branched, and distributed to all ONUs.

At this time, since the transmission time is divided, the downstream optical signal having the wavelength λ1 from the main OLT 11 and the sub OLT 12 does not collide on the optical fiber 2.
The wavelength demultiplexing filter 33i in the ONU 33 enables the input of an optical signal having the wavelength λ1 instead of the wavelength λ2. Further, as shown in FIG. 9, the output of the gate frame at the upstream transmission time from the gate frame decoding generator 12o to the ONUs 33 and 34 may be output after waiting for the downstream transmission possible time. Communication can be performed without interfering with the downstream frame or downstream gate frame from the main OLT 11.

  As described above, according to the fourth embodiment, in addition to the effects of the first embodiment, the main OLT 11 has its own downlink if it is within the downlink transmittable time range other than the downlink transmittable time set in the sub OLT 12. The transmission time can be set, and the secondary OLT 12 can independently set the downlink transmission time as long as it is within the downlink transmittable time range set by the main OLT 11, and the main OLT 11 and the sub OLT 12 are independent of each other. The setting can be changed, and further, the management independence can be enhanced.

  In addition, since it is not necessary to use the special wavelength λ2, it is possible to share parts between the device of the communication carrier A and the device of the communication carrier B, and the effect of reducing the cost of the sub-OTT 12 and the ONU 33 is achieved. There is.

  Furthermore, this embodiment is applicable to a PON system capable of detecting a failure of the main OLT 11 and the sub OLT 12 as shown in the second embodiment and the third embodiment, or in which three or more OLTs are connected. A configuration in which the wavelength of the downstream optical signal 4 is the same may be applied, and in that case, there is an effect obtained by adding the effects of both the embodiments.

Embodiment 5 FIG.
FIG. 10 is a block diagram showing a PON system according to the fifth embodiment of the present invention. In the figure, this PON system is transmitted upstream from the main OLT 11 to the sub OLT 12 in addition to the PON system shown in the first embodiment. An electric signal line (electric signal line) 51 for transmitting a possible time by an electric signal is provided, and the optical fiber 2 from the star coupler 4 to the sub OLT 12 is deleted.

FIG. 11 is a block diagram showing details of the OLT and ONU according to the fifth embodiment of the present invention. In the figure, the gate frame generator 11k in the main OLT 11 uses the electric signal line to indicate the upstream transmission possible time of the secondary OLT 12 by an electric signal. 51 is transmitted. Further, the gate frame decoding generator 12q in the secondary OLT 12 receives the uplink transmittable time from the electric signal line 51.
In FIG. 11, the optical fiber 2 from the star coupler 4 to the secondary OLT 12, the wavelength demultiplexing filter 12i in the secondary OLT 12, and the optical receiver 12j shown in FIG. 2 are omitted.
Since other configurations are the same as those in the first embodiment, a duplicate description is omitted.

Next, the operation will be described.
In the fifth embodiment, in the configuration described in the first embodiment, the uplink transmission possible time of the secondary OLT 12 generated by the gate frame generator 11k in the main OLT 11 is transmitted to the electric signal line 51 by an electric signal. is there.

As described in the fourth embodiment, in addition to the uplink transmittable time, the downlink transmittable time may be transmitted to the electrical signal line 51 by an electrical signal. In this case, the uplink transmittable time and the downlink transmission are possible. In addition to the possible time, an identifier that can identify whether it is an uplink transmittable time or a downlink transmittable time may be added.
In addition, as described in the third embodiment, when three or more OLTs are provided and the uplink transmittable time and downlink transmittable time are transmitted to a plurality of secondary OLTs using electrical signals, the secondary OLT can be identified. A simple identification number may be added.

  As described above, according to the fifth embodiment, by transmitting the uplink transmittable time or the downlink transmittable time by the electric signal from the main OLT 11 to the sub OLT via the electric signal line 51, it is generally expensive wavelength multiplexing. There is an effect that the production cost of the sub-OTT 12 can be reduced without adding the configuration of the separation filter 12i, the optical receiver 12j, and the like.

  In addition, the configuration in which the uplink transmittable time or the downlink transmittable time is transmitted from the main OLT 11 to the sub OLT via the electric signal line 51 by the electric signal in the fifth embodiment is described in the second embodiment and the third embodiment. Applied to a PON system capable of detecting a failure of the main OLT 11 and the secondary OLT 12, and the secondary OLT may detect a failure without reception by an electric signal and act as a substitute for the main OLT 11 and the secondary OLT 12. In this case, there is an effect obtained by adding the effects of both the embodiments.

Embodiment 6 FIG.
FIG. 12 is a block diagram showing a PON system according to Embodiment 6 of the present invention. In the figure, this PON system is a communication business in which the main OLT 11 and the sub OLT 12 in the central office 1 are connected via a switch (switching means) 61. Is connected to the upper network 21 of the user A.

Further, in the PON system according to the sixth embodiment, as shown in the fourth embodiment, a downstream optical signal is transmitted from the main OLT 11 and the sub OLT 12 with the wavelength λ1 having the same wavelength. Further, as shown in the second embodiment, the secondary OLT 12 is provided with functions for detecting the failure of the main OLT 11 and setting proxy for the uplink transmittable time and downlink transmittable time. Further, both the main OLT 11 and the sub OLT 12 have ONUs 31 and 32 belonging to the same subordinate.
Other configurations are the same as those in the first embodiment, and thus redundant description is omitted.

Next, the operation will be described.
The sixth embodiment has ONUs 31 and 32 to which both the main OLT 11 and the sub OLT 12 belong, the failure detection function of the main OLT 11 in the sub OLT 12 shown in the second embodiment, the uplink transmittable time, and the downlink transmittable By applying the time setting proxy function, the main OLT 11 is used for the regular system and the secondary OLT 12 is used for the standby system.

In the sixth embodiment, only the telecommunications carrier A operates the PON system, and the telecommunications carrier A installs both the main OLT 11 and the sub OLT 12.
Normally, the switch 61 is connected to the main OLT 11 side, and the upper network 21 of the communication carrier A and the main OLT 11 are connected.

The operations of the main OLT 11 and the sub OLT 12 are the same as those in the fourth embodiment, but the main OLT 11 notifies the sub OLT 12 that there is no transmittable time for both the uplink transmittable time and the downlink transmittable time. Further, it is set that both the main OLT 11 and the sub OLT 12 belong to the same ONUs 31 and 32.
With this configuration, each of the ONUs 31 and 32 communicates with the main OLT 11 during normal operation, and the sub OLT 12 performs an operation of only monitoring the downstream optical signal.

  The secondary OLT 12 uses the fact that the downstream optical signal from the main OLT 11 does not receive the transmission possible time “no transmission time” for the secondary OLT 12 even when the predetermined time has been set in advance. At this time, the switch 61 is connected to the secondary OLT 12 side, and the upper network 21 of the communication carrier A and the secondary OLT 12 are connected. Further, according to the operation described in the second embodiment, the secondary OLT 12 performs time allocation of the uplink transmittable time and the downlink transmittable time for all times.

Since the same ONUs 31 and 32 as the main OLT 11 are registered in the secondary OLT 12, the ONUs 31 and 32 are changed from the path of the main OLT 11, the switch 61 and the higher level network 21 to the path of the secondary OLT 12, the switch 61 and the higher level network 21. Thus, communication can be continued.
With the above operation, redundancy for the failure of the main OLT 11 can be realized.

As described above, according to the sixth embodiment, when the failure of the main OLT 11 is detected in the secondary OLT 12, the uplink transmission time and the downlink transmission time are set instead of the main OLT 11, and therefore the main OLT 11 is stopped. The operation can be continued, and a plurality of OLTs can be provided, and each OLT can independently change the setting and stop due to a failure, thereby improving the management independence.
Needless to say, the various configurations shown in the first to fifth embodiments can be applied to the configuration shown in the sixth embodiment.

  1 central office, 2 optical fibers, 3, 4 star coupler (combining and distributing means), 5-7 subscriber premises, 11 main OLT (main station side device, first station side device), 11a, 12a, 13a upper side Interface, 11b, 12b, 13b, 31e, 33e, 35e PON clock, 11c, 11j, 11k Gate frame generator, 11d, 12d, 13d, 13e Synthesizer, 11e, 12e, 12m, 12p, 13e, 13g, 31h, 33h, 35h optical transmitter, 11f, 12f, 12i, 12q, 13f, 13i, 31a, 33a, 33i, 35a wavelength demultiplexing filter, 11g, 12j, 12g, 13j, 31b, 33b, 35b optical receiver, 11h, 12h, 13h, 31c, 33c, 35c distributor, 11i, 12n downstream queue, 12 secondary OLT ( Station side device, second station side device), 12c, 12k, 12l, 12o, 12q, 13c gate frame decoding generator, 13 sub OLT (third station side device), 21, 22 upper network, 31-35 ONU (Optical line terminator), 31d, 33d, 35d User side interface, 31f, 33f, 35f Gate frame decoder, 31g, 33g, 35g Up queue, 41-43 User terminal, 51 Electric signal line (electric signal line) 61 switch (switching means).

Claims (10)

The substation-side devices are connected to different higher-level networks, and information input from the connected higher-level networks is transmitted as a downstream optical signal to a plurality of optical line termination devices via optical fibers, and the plurality of optical In the main station side device that receives the upstream optical signal of the same wavelength via the optical fiber from the line terminator and outputs the received information to the connected upper network,
Set the uplink transmission time of the optical line terminating device belonging to the main station side device and transmit it to the optical fiber, and set the uplink transmittable time of the substation side device excluding the set uplink transmission time. , Receiving the upstream optical signal from the optical line termination device belonging to the master station side device, and outputting the received information to the upper network to be connected ,
A main station side device, wherein a downlink transmittable time of the sub station side device is set, and a downlink optical signal is transmitted via an optical fiber at a downlink transmission time excluding the set downlink transmittable time . Each of the main station side devices is connected to different upper networks, and information input from the connected upper network is transmitted to the optical line terminator as a downstream optical signal via an optical fiber, and from the optical line terminator. In the sub-station side device that receives the upstream optical signal of the same wavelength via the optical fiber and outputs the received information to the connected upper network,
Based on the uplink transmittable time set by the main station side device, the uplink transmission time of the optical line termination device belonging to the sub station side device is set and transmitted to the optical fiber, and the sub station side device Accept upstream optical signals from subordinate optical line terminators and output the accepted information to the upper network to be connected ,
A sub-station apparatus, wherein a downlink transmission time is set based on a downlink transmission available time set by the main station-side apparatus, and a downlink optical signal is transmitted via an optical fiber at the downlink transmission time . Each is connected to a different higher level network, transmits downstream optical signals of the same wavelength to a plurality of optical line terminators via an optical fiber, and upstream light of the same wavelength from the plurality of optical line terminators via an optical fiber. 1st to n-th (n is an arbitrary natural number greater than or equal to 2) station-side devices that receive signals,
The first station side device is:
Set the upstream transmission time of the optical line termination device belonging to the local station side device and transmit it to the optical fiber and set the upstream transmission possible time of the other station side device excluding the set upstream transmission time, Receiving an upstream optical signal from an optical line termination device belonging to the local station side device, and outputting the received information to a higher-level network to be connected;
Set the downlink transmittable time of the other station side device, and transmit the downstream optical signal via the optical fiber at the downlink transmission time excluding the set downlink transmittable time,
The n th station side device is:
Based on the upstream transmission possible time set by the first station side device, the upstream transmission time of the optical line termination device belonging to the local station side device is set and transmitted to the optical fiber, and the local station device Receiving the upstream optical signal from the optical line termination device belonging to the subordinate, and outputting the received information to the upper network to be connected ,
A central station characterized in that a downlink transmission time is set based on a downlink transmittable time set by the first station side device and a downlink optical signal is transmitted via an optical fiber at the downlink transmission time . The first station side device
4. The central station according to claim 3, wherein the upstream transmission possible time or the downstream transmission possible time is transmitted by an optical signal to the other station side apparatus via an optical fiber. The first station side device
4. The central station according to claim 3, wherein the upstream transmission available time or the downstream transmission available time is transmitted by an electrical signal to the other station side device via the electrical signal line. The second station side device
When the uplink transmission available time is not received from the first station side device, it is determined that the first station side device is out of order, and is assigned to the second station side device instead of the first station side device. Set the uplink transmittable time and downlink transmittable time ,
On the other hand, the central station according to any one of claims 3 to 5 , wherein the upstream transmission time of the optical line termination device belonging to the first station side device is not set . 1st to n-th (n is an arbitrary natural number of 2 or more) station-side devices;
A plurality of optical line termination devices provided so as to belong to any one of the first to n-th station-side devices;
Connected via optical fiber between the first to nth station side devices and the plurality of optical line terminators, and combines the downstream optical signals of the same wavelength transmitted from the first to nth station side devices. And distributing to the plurality of optical line terminators to synthesize upstream optical signals having the same wavelength transmitted from the plurality of optical line terminators and distribute to the first to n-th station side devices. And
The first station side device is:
Set the upstream transmission time of the optical line termination device belonging to the local station side device and transmit it to the optical fiber and set the upstream transmission possible time of the other station side device except for the upstream transmission time set above,
Set the downlink transmittable time of the other station side device, and transmit the downstream optical signal via the optical fiber at the downlink transmission time excluding the set downlink transmittable time,
The n th station side device is:
Based on the possible upstream transmission time set by the first station side device, set the upstream transmission time of the optical line termination device belonging to the local station side device, and transmit to the optical fiber,
Based on the downlink transmittable time set by the first station side device, the downlink transmission time is set and the downlink optical signal is transmitted via the optical fiber at the downlink transmission time,
The plurality of optical line terminators are
An upstream optical signal is transmitted via the optical fiber at an upstream transmission time set by any one of the first to n-th station-side devices received via the combining / distributing means and the optical fiber. An optical communication system. The first station side device
8. The optical communication system according to claim 7 , wherein an uplink transmission available time and a downlink transmission available time are transmitted as optical signals to the other station side device via the optical fiber and the combining / distributing means. The first station side device
Optical communication system of claim 7, wherein the transmitting the electrical signals and uplink transmittable time and downlink transmission available time to another station apparatus via an electric signal line. The second station side device
When the uplink transmission available time is not received from the first station side device, it is determined that the first station side device is out of order, and is assigned to the second station side device instead of the first station side device. Set the uplink transmittable time and downlink transmittable time ,
On the other hand, the optical communication system according to any one of claims 7 to 9 in which the uplink transmission time of the optical line terminal belonging under the first station apparatus is characterized in that it does not set.

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