JP4909376B2 - Passive optical network system and wavelength allocation method - Google Patents

Description

  The present invention relates to a passive optical network system and a wavelength allocation method, and more particularly to a passive optical network system and a wavelength allocation method in which a plurality of subscriber connection devices share an optical transmission line and communicate by wavelength division multiplexing.

  PON (Passive Optical Network, Passive Optical Network, Passive Optical Network, Passive Optical Network) consists of OLT (Optical Line Termination, Optical Transmission Line Terminator, Optical Terminator) and multiple ONUs (Optical Network Unit) or ONT (Optical Network). Network Termination (hereinafter also referred to as an optical network unit). A signal from a terminal (PC or the like) connected to the ONU is optically multiplexed as an optical signal from the ONU via an optical fiber and an optical splitter to the OLT and sent to the OLT. After various signal processing, the OLT performs communication from one ONU terminal to another ONU terminal of the PON or NW terminal.

  Examples of the optical multiplexing scheme include TDM (Time Division Multiplexing), WDM (Wavelength Division Multiplexing), and CDM (Code Division Multiplexing). For example, ITU-T Recommendation G. The G-PON specified in 984.3 uses different wavelengths in upstream and downstream, and communication between the accommodation station (OLT) placed in the station and the network unit (ONU) placed in each user is performed for each ONU. In this method, signal communication is performed by time division (TDM) in which signal communication time is allocated (see, for example, Non-Patent Document 1).

On the other hand, in the WDM system, a plurality of waves having different wavelengths are multiplexed on the upstream signal and downstream signal between the OLT and the ONU, and each ONU communicates with the OLT by receiving and transmitting a specific wavelength. By performing communication by assigning individual wavelengths to each ONU from the OLT, it can be expected that the communication band is significantly improved. One implementation method of WDM-PON is to assign one wavelength to each ONU for each upstream and downstream, that is, the number of wavelengths used in one PON is twice the maximum number of connected ONUs.
Also, an example of initial setting of a path on the B-PON system is disclosed (for example, see Patent Document 1).

US Pat. No. 6,097,736

ITU-T Recommendation G. 984.3

In the WDM-PON, each ONU needs to use a specific wavelength in order to connect to the OLT and start communication. For example, in a WDM-PON in which a maximum of 32 ONUs can be connected, it is complicated for the installer to set other than the wavelengths used by the OLT and other ONUs when installing the ONU. Considering the ease of construction, rather than preparing 32 ONUs with different fixed wavelengths, ONUs having each wavelength variable function can be negotiated with the OLT automatically to determine the wavelength and be connected. desirable. However, in the initial state, since the ONU cannot know which wavelength should be used for connection, it is difficult for each ONU to negotiate with the OLT which wavelength should be used for communication. is there.
In view of the above points, the present invention provides a passive optical network system and a wavelength allocation method in which each ONU negotiates with the OLT at the time of initial setting and automatically obtains a wavelength that can be used by the ONU. For the purpose. It is another object of the present invention to provide a passive optical network system and a wavelength allocation method that make effective use of wavelength resources and that are easy to install.

  The above problem is solved by fixing one wavelength that can be used for negotiation of the assigned wavelength by default, and the newly connected ONU uses the negotiation wavelength first. For this purpose, the OLT includes 32 light sources having wavelengths λd1 to λd32 that can be used for downlink communication. On the other hand, the ONU has a wavelength tunable filter that can selectively receive one of 32 wavelengths λd1 to λd32 that can be used for downlink communication, and one of the 32 wavelengths λu1 to λu32 that can be used for uplink communication. A tunable light source capable of selectively emitting light. As soon as the ONU is connected, the tunable filter is switched so that a reception wavelength for negotiation (for example, λd32) can be selectively received. Subsequently, the ONU transmits a wavelength allocation negotiation message to the OLT using the transmission wavelength for negotiation (for example, λu32). As a response to the wavelength allocation negotiation message using λu32, the OLT selects a wavelength other than λd32 for downlink communication and a wavelength other than λu32 for uplink communication from the unused wavelengths, and transmits a wavelength use permission signal to the ONU. . However, when the 32nd ONU which is the last ONU is connected, λd32 is selected for downlink communication and λu32 is selected for uplink communication, and a wavelength use permission signal is transmitted to the ONU. In this way, the use wavelength can be negotiated between the OLT and the ONU, and the communication of the user signal can be started using the notified wavelength.

  Further, as another means for solving the above problem, the connected ONU sequentially switches the reception wavelength, detects the unused wavelength, and negotiates the wavelength using the unused wavelength. The problem can be solved. More specifically, the OLT emits only wavelengths that are in use for communication with ONUs that have already completed wavelength allocation, and extinguishes unused wavelengths. As soon as the ONU is connected, the wavelength tunable filters are sequentially switched to measure the presence or absence of reception power of 32 wavelengths that may be used in the downstream. A wavelength with zero reception power can be regarded as an unused wavelength. Subsequently, the ONU selects one wavelength from which reception power is zero. For example, if the selected wavelength is λu10, the ONU transmits a wavelength allocation negotiation message to the OLT using λu10, and receives the wavelength variable filter. Is set by itself so as to selectively receive a predetermined wavelength (for example, λd10) used as a pair with λu10. The OLT emits a light source corresponding to λd10 and transmits a response to the wavelength allocation negotiation message using λd10. In this way, it is possible to negotiate the wavelength to be used between the OLT and the ONU and decide to use the wavelength used for the negotiation as it is or to assign another wavelength.

The present invention includes, for example, an OLT, an optical fiber, an optical splitter, and a plurality of ONUs, and the ONU includes a wavelength control unit that variably controls a transmission wavelength and a reception wavelength.
The OLT is a transmission light source having a wavelength equal to the maximum number of ONUs that can be connected and having different wavelengths, a receiver that can simultaneously receive all signals having the same number of wavelengths as the number of ONUs, a table that manages the assigned wavelengths for each ONU, A control message transmission and reception unit for negotiating wavelength allocation with
One of the features of the ONU is that it includes a control message transmission / reception unit for negotiating wavelength assignment, and a unit for storing a wavelength to be set in the wavelength control unit based on a result of the negotiation based on the control message.

In addition, the present invention has, for example, a reset unit that initializes a control wavelength by the wavelength control unit in the ONU to a predetermined value.
In the present invention, for example, the ONU detects a presence / absence of a received signal for all wavelengths that can be used for downlink communication in a WDM-PON system, and a wavelength set in the wavelength control unit based on the result of the presence / absence of the received signal. One of the features is that it has a portion for storing.
In the OLT, for example, a part for detecting the presence / absence of a received signal for all wavelengths that can be used for uplink communication of the WDM-PON system, a result of the presence / absence of the received signal, and a predetermined downstream wavelength One feature is that a transmission control unit that stops transmission of a downstream wavelength signal corresponding to an upstream wavelength without a reception signal is provided based on the correspondence between the upstream wavelength and the upstream wavelength.

The present invention includes, for example, an OLT, an optical fiber, an optical splitter, and a plurality of ONUs, and the ONU includes a wavelength control unit that variably controls a transmission wavelength and a reception wavelength.
The OLT is a transmission light source having a wavelength equal to the maximum number of ONUs that can be connected and having different wavelengths, a receiver that can simultaneously receive all signals having the same number of wavelengths as the number of ONUs, a table that manages the assigned wavelengths for each ONU, A control message transmission and reception unit for negotiating wavelength allocation with
At the initial startup time, the ONU transmits a control message to the OLT requesting assignment of a wavelength used for communication with the OLT using one of wavelengths usable in the WDM-PON system.
Subsequently, the OLT transmits a control message notifying the wavelength assigned to the communication with the ONU based on the received control message,
Furthermore, one of the features is that the ONU switches its transmission wavelength and reception wavelength based on the control message received from the OLT.

In the present invention, for example, at the time of initial startup, the ONU selects an upstream wavelength allocated to the last ONU to which the OLT can be connected, and transmits a control message requesting the wavelength allocation to the OLT. And
Subsequently, the OLT receives a control message for requesting assignment of a wavelength used for communication with the OLT using the upstream wavelength assigned to the last connectable ONU,
Subsequently, the OLT transmits a control message notifying the wavelength assigned to the communication with the ONU using the downstream wavelength assigned to the last connectable ONU,
Subsequently, the ONU receives a control message for assigning a wavelength from the OLT using a downstream wavelength assigned to the last connectable ONU,
Subsequently, one of the features is that the ONU switches its transmission wavelength and reception wavelength based on the control message received from the OLT in the wavelength control unit.
In the present invention, for example, the OLT detects the presence / absence of a reception signal for all wavelengths that can be used for uplink communication of the WDM-PON system, and determines the result of the presence / absence of the reception signal and a predetermined downlink. Based on the correspondence between the wavelength and the upstream wavelength, the transmission of the downstream wavelength corresponding to the upstream wavelength without the received signal is stopped,
The ONU detects the presence / absence of a received signal for all wavelengths that can be used for downlink communication at initial startup,
Subsequently, the ONU selects one wavelength from the wavelengths detected as having no received signal, and transmits a control message requesting assignment of a wavelength used for communication with the OLT to the OLT,
Subsequently, the OLT receives the control message and uses the downstream wavelength corresponding to the wavelength used in the control message from the ONU based on the correspondence between the downstream wavelength and the upstream wavelength determined in advance. Send a control message to notify the wavelength to be assigned to
Subsequently, the ONU performs the assignment of the wavelength from the OLT using the downstream wavelength corresponding to the wavelength used in the control message from the ONU based on the predetermined correspondence between the downstream wavelength and the upstream wavelength. Receive the message,
Subsequently, one of the features is that the ONU switches its transmission wavelength and reception wavelength based on the control message received from the OLT in the wavelength control unit.

According to the first solution of the present invention,
An optical termination device, an optical splitter, and a plurality of optical network units connected to the optical termination device via an optical fiber and the optical splitter, and the optical termination device and the optical network unit are wavelength division multiplexed. In a passive optical network system for communication,
The optical terminator is:
A plurality of first transmitters having light sources having different wavelengths from each other;
A plurality of first receivers for receiving signals of a plurality of wavelengths;
A wavelength management table for managing wavelength information allocated for communication with each optical network unit for each identifier of the optical network unit;
A first control unit that receives a control message for assigning a wavelength from the optical network unit, and assigns a wavelength for communication between the optical terminal unit and the optical network unit;
A transmission valid control unit for enabling each of the plurality of first transmitters to be output by enabling or disabling only the wavelength being communicated with the optical network unit;
Each of the optical network units is
A second receiver for receiving a signal of a set wavelength;
A second transmitter for transmitting a signal of a set wavelength;
A received power detector for detecting received power at the second receiver;
A second control unit for transmitting a control message for assigning a wavelength via the second transmitter;
A wavelength control unit that variably controls the transmission wavelength of the second transmitter and the reception wavelength of the second receiver;
The second control unit of the optical network unit is
The wavelength control unit sequentially switches the reception wavelength of the second receiver to the transmission wavelengths of the plurality of first transmitters of the optical termination device,
The reception power detection unit detects the reception power of the downlink signal from the optical termination device to the optical network unit for each wavelength, and determines the first downlink wavelength that is not used for other communication based on the reception power. Seeking
The wavelength control unit sets the reception wavelength of the second receiver to the first downstream wavelength, and sets the transmission wavelength of the second transmitter to a first upstream wavelength that is paired with the first downstream wavelength. And
Using the first upstream wavelength, a control message for requesting allocation of a wavelength used for communication with the optical termination device is transmitted to the optical termination device,
The optical terminator is:
When the control message is received, the first downstream wavelength and the first upstream wavelength are allocated to the communication with the optical network unit, or the second downstream wavelength that is not used for other communication with reference to the wavelength management table, and Assigning a second upstream wavelength to the communication with the optical network unit;
The transmission valid control unit enables the first transmitter corresponding to the first downstream wavelength or the second downstream wavelength,
The passive optical network system is provided in which the optical network unit and the optical termination device communicate with each other by the first downstream wavelength and the first upstream wavelength, or by the second downstream wavelength and the second upstream wavelength.

According to the second solution of the present invention,
An optical termination device, an optical splitter, and a plurality of optical network units connected to the optical termination device via an optical fiber and the optical splitter, and the optical termination device and the optical network unit are wavelength division multiplexed. A wavelength allocation method in a passive optical network system for communication,
Optical network unit
The reception wavelength of the receiver of the optical network unit is sequentially switched to each transmission wavelength of the plurality of transmitters of the optical termination device, and for each wavelength, the reception power of the downstream signal from the optical termination device to the optical network unit is detected,
Obtaining a first downstream wavelength that is not used for other communications based on the received power;
The reception wavelength of the receiver of the optical network unit is set to the obtained first downstream wavelength, and the transmission wavelength of the transmitter of the optical network unit is set to the first upstream wavelength paired with the first downstream wavelength;
Using the first upstream wavelength, a control message requesting assignment of a wavelength used for communication with the optical termination device is transmitted to the optical termination device,
The optical terminator is
When receiving the control message, the first downlink wavelength and the first uplink wavelength are assigned to the communication with the optical network unit, or the wavelength information assigned for the communication with each optical network unit for each identifier of the optical network unit. Referring to the wavelength management table for managing the second downstream wavelength and the second upstream wavelength that are not used for other communication, the communication with the optical network unit is assigned,
Enabling the transmitter of the optical termination device corresponding to the first downstream wavelength or the second downstream wavelength;
The wavelength allocation method is provided in which an optical network unit and an optical termination device communicate with each other by the first downstream wavelength and the first upstream wavelength, or by the second downstream wavelength and the second upstream wavelength.

According to another solution of the invention,
An optical termination device, an optical splitter, and a plurality of optical network units connected to the optical termination device via an optical fiber and the optical splitter, and the optical termination device and the optical network unit are wavelength division multiplexed. In a passive optical network system for communication,
The optical termination device and the optical network unit have a plurality of wavelengths for communication, a first wavelength of the plurality of wavelengths is predetermined as a wavelength for transmitting and receiving a control message, and the first The system to which a second wavelength for communicating with each optical network unit among the plurality of wavelengths including one wavelength is assigned,
The optical terminator is:
A plurality of first transmitters having light sources having different wavelengths from each other;
A plurality of first receivers for receiving signals of a plurality of wavelengths;
A wavelength management table for managing second wavelength information assigned for communication with each optical network unit for each identifier of the optical network unit;
A first controller for transmitting and receiving first and second control messages for assigning wavelengths to and from the optical network unit, and for assigning a second wavelength for communication with the optical network unit;
Each of the optical network units is
A second receiver for receiving a signal of a set wavelength;
A second transmitter for transmitting a signal having a set wavelength;
A second controller for transmitting and receiving first and second control messages for assigning wavelengths via the second transmitter and the second receiver;
A wavelength control unit that variably controls the transmission wavelength of the second transmitter and the reception wavelength of the second receiver to the first wavelength or the second wavelength;
The optical network unit sends a first control message for requesting allocation of a second wavelength used for communication between the optical termination device and the own optical network unit by the second transmitter preset to the first wavelength. To the device,
When receiving the first control message from the optical network unit, the optical termination device refers to the wavelength management table and assigns a second wavelength that is not assigned to other communication to the communication with the optical network unit, A second control message for notifying the allocated second wavelength information is transmitted to the optical network unit at a first wavelength;
The optical network unit receives the second control message by the second receiver set in advance to the first wavelength, and based on the second control message, the wavelength control unit transmits the transmission wavelength of the second transmitter. And the reception wavelength of the second receiver is set to the assigned second wavelength,
The passive optical network system is provided in which the optical network unit and the optical termination device communicate with each other by the second wavelength.
According to another solution of the invention,
An optical termination device, an optical splitter, and a plurality of optical network units connected to the optical termination device via an optical fiber and the optical splitter, and the optical termination device and the optical network unit are wavelength division multiplexed. In a passive optical network system for communication,
The optical termination device and the optical network unit have a plurality of wavelengths for communication, a first wavelength of the plurality of wavelengths is predetermined as a wavelength for transmitting and receiving a control message, and the first A wavelength allocation method for allocating a second wavelength for communicating with each optical network unit from among the plurality of wavelengths including one wavelength,
The optical network unit transmits a first control message requesting allocation of the second wavelength used for communication between the optical termination device and the own optical network unit to the optical termination device by a transmitter preset to the first wavelength,
When receiving the first control message from the optical network unit, the optical terminal device refers to the wavelength management table that manages the second wavelength information allocated for communication with each optical network unit, and assigns it to other communication. A second wavelength that is not assigned is assigned to communication with the optical network unit, and a second control message for notifying the assigned second wavelength information is transmitted to the optical network unit at the first wavelength;
The optical network unit receives the second control message by the receiver preset to the first wavelength, and based on the second control message, the second wavelength assigned to the transmission wavelength of the transmitter and the reception wavelength of the receiver is assigned. Set the wavelength to
The wavelength allocation method is provided in which an optical network unit and an optical termination device communicate with each other using the second wavelength.

  According to the present invention, it is possible to provide a passive optical network system and a wavelength allocation method in which each ONU negotiates with the OLT at the time of initial setting and the wavelength that can be used by the ONU is automatically acquired in the WDM PON system. Further, according to the present invention, it is possible to provide a passive optical network system and a wavelength allocation method that make effective use of wavelength resources and easy installation work.

The block diagram of an optical access network (PON). Explanatory drawing of wavelength allocation. The structural example of OLT in 1st Embodiment. 2 is a configuration example of an ONU in the first embodiment. 6 is a configuration example of an OLT connection management table. The structural example of a wavelength management table. FIG. 6 shows an example of the configuration of a user signal transfer frame, a wavelength request signal, and a wavelength assignment signal. The structural example of a wavelength confirmation signal and a control wavelength notification signal. The wavelength allocation sequence diagram in 1st Embodiment. Sequence diagram (1) at the time of ONU disconnection and connection in the first embodiment. Sequence diagram (2) when the ONU is disconnected and connected in the first embodiment. Transition example of wavelength management table (1). Transition example (2) of wavelength management table. The structural example of OLT in 2nd Embodiment. The structural example of ONU in 2nd Embodiment. The wavelength allocation sequence diagram in 2nd Embodiment.

1. First embodiment (system configuration)
FIG. 1 shows the configuration of an optical access network to which the present embodiment is applied.
The PON 10 includes an optical splitter 100, a trunk fiber 110, a plurality of branch fibers 120, an OLT 200, and an ONU (or ONT) 300. The PON 10 is connected to the PSTN / Internet 20 to transmit and receive data. For example, a telephone 400 and a personal computer 410 can be connected to the ONU 300. For example, 32 ONUs 300 can be connected to the OLT 200 via one trunk fiber 110, the optical splitter 100, and the branch fiber 120. FIG. 1 shows five ONUs, and the wavelengths used for communication with the OLT are different. In the illustrated example, the ONU 300-1 uses wavelengths λd1 and λu1, the ONU 300-2 uses λd2 and λu2, the ONU 300-4 uses λd4 and λu4, and the ONU 300-n uses λdn and λun. In this embodiment, λd is the wavelength of the downstream signal, and λu is the wavelength of the upstream signal. In the signal transmitted from the OLT 200 to the ONU 300 (downward), the signal addressed to each ONU 300 is wavelength-multiplexed and transmitted. The signal received by the ONU 300 is received within the ONU 300 by selecting the wavelength determined according to the present embodiment as to whether or not the signal is addressed to itself, and based on the destination of the signal, the telephone 400 and the personal computer 410 Sent to. In the direction from the ONU 300 to the OLT 200 (upward direction), signals transmitted from the ONU 300-1, ONU 300-2, ONU 300-3, ONU 300-4, and ONU 300-n are wavelength-multiplexed after passing through the optical splitter 100. The OLT 200 is reached.

FIG. 2 shows an example of wavelength arrangement in the present embodiment.
For example, in a WDM-PON that connects up to 32 ONUs, generally, the 1300 mn wavelength band and the 1500 wavelength band can be used for signal transmission. The 1300 nm wavelength band specifically uses 1260 nm to 1360 nm, and the 1500 nm wavelength band uses 1480 nm to 1580 nm. Recommended for 983.1. To accommodate 32 wavelengths in each band, the wavelength of the upstream signal (λu1 to λu32) is a value from 1270 nm to 1332 nm at intervals of 2 nm, and the wavelength of the downstream signal (λd1 to λd32) is also 1482 nm at intervals of 2 nm. Values from 1 to 1544 nm can be used.

FIG. 3 shows a configuration example of the OLT 200 of the present embodiment.
The OLT 200 includes, for example, a network IF 201, a packet buffer 202, a signal distribution unit 203, a connection management table 221, a PON frame generation unit 204, a driver 205, an E / O 206, a WDM filter 207, an O / O E208, amplifier 209, clock extraction unit 210, PON frame decomposition unit 211, signal multiplexing unit 216, packet buffer 217, network IF 218, CPU (first control unit) 223, memory 224, message A transmission buffer 222, a message reception buffer 223, and a wavelength management table 220 are included.

  The network IF 201 receives a signal from the PSTN / Internet 20. This signal is temporarily stored in the packet buffer 202. The signal distribution unit 203 reads the label attached to the packet signal, reads the corresponding ONU number (ONU-ID or PON-ID) in the connection management table 221, and reads the PON frame generation units 204-1 to 204-n. The packet signal is transferred to the corresponding block in the.

  When the maximum number of ONUs that can be connected is n, the OLT 200 includes n PON frame generation units 204, drivers 205, and E / Os 206 (these are referred to as first transmitters). The PON frame generation unit 204 generates an electrical transmission signal by adding the overhead of the PON section. The driver 205 drives the E / O 206 with current to convert an electric signal into an optical signal, and transmits the signal to the OLT 200 via the WDM filter 207 and the fiber 110.

  On the other hand, when the maximum number of ONUs that can be connected in the OLT 200 is n, the O / E 208, the amplifier 209, the clock extraction unit 210, and the PON frame decomposition unit 211 (these are referred to as first receivers) are provided. Yes. A signal received from the OLT 200 via the WDM filter 207 and separated for each wavelength is converted into an electric signal by the O / E 208. Further, the signal is amplified by the amplifier 209 and retimed by the clock extraction unit 210. The overhead is separated by the PON frame decomposition unit 211, and a signal is output from the network IF 218 to the network side via the signal multiplexing unit 216 and the packet buffer 217.

  Note that the OLT 200 can include, for example, the same number of first transmitters and first receivers as the maximum number of ONUs that can be connected to the OLT 200. In this embodiment, one downstream wavelength and one upstream wavelength are allocated to one ONU 300, but a plurality of downstream wavelengths and upstream wavelengths may be allocated to one ONU. In this case, the ONU 300 includes a plurality of second transmitters and a plurality of second receivers, and the OLT 200 can include a plurality of first transmitters and first receivers that are larger than the number of connected ONUs. .

  The CPU 223 and the memory 224 execute monitoring control of each part in the OLT 200 as a pair. Further, the CPU 223 performs a setting for associating the label of the packet in the connection management table 221 with the number of the destination ONU according to an instruction from the host. The CPU 223 uses the message transmission buffer 222 and the message reception buffer 223 to exchange wavelength assignment messages with each of the ONUs 300-1 to 300-n, and registers the assigned wavelength for each ONU in the wavelength management table 220.

FIG. 5 shows a configuration example of the connection management table 221.
The connection management table 221 includes an entry that stores the serial number of the ONU 300, an entry that stores a connection label, and an entry that stores an ONU-ID. Prior to the activation of the ONU 300, for example, a value of a connection label corresponding to each serial number is set by an instruction from the CPU 223. As the connection label, for example, a value of VLAN (Virtual Local Area Network) -ID can be used. For example, the value of VLAN-ID 1 is set for the value of “A0000001” as the serial number of the ONU. Thereafter, when the ONU 300 is activated, the ONU serial number and the ONU-ID are automatically associated with each other. The CPU 223 sets the corresponding ONU-ID for each ONU serial number. For example, 1 is set as the ONU-ID value for the value “A0000001” as the serial number.

  As described above, the signal distribution unit 203 reads the connection label (for example, VLAN-ID) given to the packet signal, reads the corresponding ONU number with reference to the connection management table 221, and then generates the PON frame generation unit. The packet signal is transferred to the corresponding block in 204-1 to 204-n. The PON frame generation units 204-1 to 204-1 correspond to ONT-IDs 1 to n, for example. For example, a packet signal assigned 1 as the VLAN-ID value is distributed toward the PON frame generation unit 204-1 corresponding to the ONU-ID value 1.

FIG. 6 shows a configuration example of the wavelength management table 220.
The wavelength management table 220 includes an ONU-ID entry, a serial number entry, a downstream wavelength entry, and an upstream wavelength entry, and each value is registered. When the ONU 300 is unregistered or not connected, the serial number entry is set to, for example, unregistered. The downstream wavelength entry and the upstream wavelength entry are set to unused values. In addition, the values of λd32 and λu32 are set in the downstream wavelength entry and the upstream wavelength entry in the row of ONU # 32. However, until ONU # 32 is registered, the upstream wavelength and downstream wavelength of ONU # 32 are common applications. Each time the ONU 300 is connected, the OLT 200 acquires the serial number of the ONU 300 by a wavelength request signal (details will be described later) from the ONU 300. The OLT 200 searches the unregistered ONU-ID and unused wavelength with reference to the wavelength management table 220, determines the ONU-ID and wavelength used for allocation, and assigns the assigned ONU in the wavelength management table 220. -Set the acquired serial number in the ID line.

FIG. 4 shows a configuration example of the ONU 300 according to the present embodiment.
The ONU 300 includes, for example, a WDM filter 301, a wavelength tunable filter 302, an O / E 303, an AGC (Automatic Gain Control) 304, a clock extraction unit 305, a PON frame termination unit 306, a user IF 307, and a PON frame generation. Unit 311, driver 312, wavelength tunable laser 313, CPU (second control unit) 323, memory 324, wavelength management memory 322, reception wavelength control unit 321, transmission wavelength control unit 320, and timer 325 A message reception buffer 308 and a message transmission buffer 310.

For example, the wavelength tunable filter 302, the O / E 303, the AGC 304, the clock extraction unit 305, and the PON frame termination unit 306 are referred to as a second receiver. The PON frame generation unit 311, the driver 312, and the wavelength tunable laser 313 are referred to as a second transmitter.
The optical signal received from the branch line fiber 120 is wavelength-separated by the WDM filter 301 and selectively passes through one of the downstream wavelengths λd1 to λd32 by the wavelength tunable filter 302. The optical signal is converted into an electric signal by the E / O 302, and the AGC 304 performs control so that the amplitude value becomes constant. In addition, the clock extraction unit 305 performs retiming, the PON frame termination unit 306 separates the overhead of the PON section, and the user signal is sent to the user IF 307 and output.

  The signal input from the user IF 307 is assembled by adding the overhead of the PON section in the PON frame generation unit 311. The assembled signal is converted into an optical signal having a wavelength set by the transmission wavelength control unit 320 by driving the wavelength tunable laser 313 with a driver 312, and transmitted to the branch fiber 120 through the WDM filter 301. .

  The CPU 323 and the memory 324 perform monitoring control of each block in the ONU 300 as a pair. For example, the CPU 323 resets the wavelengths previously determined in the wavelength management memory 322, for example, the downstream wavelength λd32 and the upstream wavelength λu32, as initial values immediately after the ONU is activated or immediately after the ONU is connected to the fiber. The reception wavelength control unit 321 sets the wavelength of the wavelength tunable filter 302 based on the value stored in the wavelength management memory 322. The transmission wavelength control unit 320 sets the wavelength of the wavelength tunable laser 313 based on the value stored in the wavelength management memory 322. Further, the CPU 323 exchanges the wavelength assignment message with the OLT 200 using the message reception buffer 308 and the message transmission buffer 310 while referring to the timer 325, and sets its own assigned wavelength in the wavelength management memory 322.

(Signal format)
7 and 8 show signal formats in the present embodiment.
FIG. 7A shows a configuration example of the format of the user signal transfer frame after the ONU is activated in the present embodiment.
The user signal 1003 includes, for example, a frame synchronization pattern 2001, a PLOAM (Physical Layer Operation Administration and Maintenance) area 2001, an OMCI (ONT Management and Control Interface) area 2002, and a frame payload 2003.

  In WDM-PON, communication after ONU activation is performed in a one-to-one connection, so that the signal can be applied with a traditional frame structure with a period of 125 microseconds. The frame synchronization pattern 2001 is used for frame synchronization. The PLOAM area 2001 is an area used for physical layer monitoring and control. 983.1. The OMCI area 2002 is an area where the internal control information of the ONU can be monitored and controlled. 983.2. A frame payload 2003 is an area for transmitting a user signal, and can map a user signal such as an Ethernet (registered trademark) signal or an ATM signal.

FIG. 7B shows a configuration example of the wavelength request signal 1000 in the present embodiment.
Since the plurality of ONUs 300 share the wavelength assignment wavelength λu32 before the ONU is activated, the wavelength request signal is preferably a burst signal in order to reduce the probability of signal collision from the plurality of ONUs 300.

  The wavelength request signal 1000 includes, for example, a burst synchronization pattern 2100, a transmission source ONU-ID 2101, a message ID (MSG-ID) 2102, a request uplink wavelength 2103, a request downlink wavelength 2104, an ONU serial number 2105, a reserved area 2106, and a CRC 2107. Including.

  The burst synchronization pattern 2100 is a sufficiently long pattern that allows the OLT 200 to achieve burst synchronization, and can be several tens to several thousand bits long depending on the performance of the receiver. When the ONU 300 is initially connected, a broadcast code is entered in the transmission source ONU-ID 2101. In the case of restarting the ONU 300, the past ONU-ID can be entered here to prompt the OLT 200 to assign the same wavelength as the past. MSG-ID 2102 is a type code indicating that this signal is a wavelength request signal. In the present embodiment, specific values are not required for the requested upstream wavelength 2103 and the requested downstream wavelength 2104. A dummy code may be inserted, or any other wavelength may be inserted.

  The ONU serial number 2105 is a number inherent to the ONU 300 and is an ITU-T recommendation G.264. 983.1 is an 8-byte code. This information is used by the OLT 200 to manage the wavelength assignment of the ONU 300. The reserved area 2106 sets the signal length to the ITU-T recommendation G.264. 983.1 Recommendation This is a free area for adjusting the length of the default PLOAM message, and can be used for future expansion. A CRC (Cyclic Redundancy Check) 2107 is assigned for the OLT 200 to check whether there is an error in the message content, and the OLT 200 does not use a message with an error.

FIG. 7C shows a configuration example of the wavelength assignment signal 1001 in this embodiment.
The wavelength allocation signal 1001 is used in the downstream direction. However, in the PON, the downstream signal takes the form of a broadcast from one OLT 200 to all ONUs 300, so the normal signal described with reference to FIG. Format can be used. For example, necessary information may be transmitted in the form of a message in the PLOAM area 2001 in FIG.

  When the wavelength allocation signal 1001 is configured using a PLOAM message, for example, it includes a transmission destination ONU-ID 2201, MSG-ID 2202, allocated uplink wavelength 2203, allocated downlink wavelength 2204, ONU serial number 2205, reserved area 2206, and CRC 2207.

  The assigned ONU-ID is entered in the transmission destination ONU-ID 2101. MSG-ID 2102 contains a type code indicating that this signal is a wavelength assignment signal. The allocated upstream wavelength 2203 and the allocated downstream wavelength 2204 are encoded with wavelengths allocated by the OLT 200. The ONU serial number 2105 is a number unique to the ONU 300. This information is used for checking whether the ONU 300 is a message addressed to itself. The reserved area 2106 sets the signal length to the ITU-T recommendation G.264. 983.1 Recommendation This is a free area for adjusting the length of the default PLOAM message, and can be used for future expansion. The CRC 2107 is assigned in order for the ONU 300 to check whether there is an error in the message content, and the ONU 300 does not use a message with an error.

FIG. 8A shows a configuration example of the wavelength confirmation signal 1002 in this embodiment.
Although the wavelength confirmation signal 1002 is in the upstream direction, since wavelength allocation is performed at this stage, the signal can be transmitted using the PLOAM message in the normal signal format described in FIG. When the wavelength confirmation signal is configured using the PLOAM message, for example, the transmission source ONU-ID 2301, MSG-ID 2302, the assigned uplink wavelength 2303, the assigned downlink wavelength 2304, the ONU serial number 2305, the reserved area 2106, and the CRC 2107 are included. MSG-ID 2302 is a code indicating that this signal is a wavelength confirmation signal. With this signal, it is possible to notify the OLT 200 that the ONU 300 can complete the wavelength setting and start communication of the user signal. Others are the same as described above.

FIG. 8B shows a configuration example of the control wavelength notification signal 1004 in the present embodiment.
When the control wavelength notification signal 1004 is configured using a PLOAM message, for example, it includes a transmission destination ONU-ID 2401, MSG-ID 2402, control uplink wavelength 2403, control downlink wavelength 2404, reserved area 2405, and CRC 2406. The transmission destination ONU-ID 2401 is a broadcast code. MSG-ID 2402 is a code indicating that this signal is a control wavelength notification signal. This signal can be used by the OLT 200 for notifying which wavelength is used as a control wavelength to the ONU 300 immediately after startup using λd32.

(Operation)
FIG. 9 shows a sequence diagram of the operation of the present embodiment.
This figure shows an operation example when the ONT 300-1 (ONU # 1), 300-2 (ONU # 2), and 300-32 (ONU # 32) are connected to the OLT 200 in order. However, ONU # 3 to ONU # 31 are omitted in this figure. The order may be an appropriate order.

  First, the wavelength allocation operation of the ONU 300-1 connected first will be described. The ONU 300-1 sets its own transmission wavelength to the management wavelength (first wavelength) λu32 based on a prior agreement immediately after power-on, and then transmits a wavelength assignment request signal (first control message) 1000-1. For example, the reception wavelength control unit 321 of the ONU 300-1 sets the wavelength of the wavelength variable filter 302 to the reception wavelength λd32 stored in the wavelength management memory 322. Also, the reception wavelength control unit 321 of the ONU 300-1 sets the wavelength of the wavelength tunable laser 313 to the transmission wavelength λu 32 stored in the wavelength management memory 322. For example, the CPU 323 generates the wavelength assignment request signal 1000-1 shown in FIG. 7B and transmits it to the OLT 200 with the wavelength λu32 by the wavelength variable laser 313 via the message transmission buffer 310.

  On the other hand, the OLT 200 constantly monitors the control signal received using the wavelength λu32 and receives the wavelength assignment request signal 1001-1 from the ONU 300. The MSG-ID 2102 can identify that the received control signal is a wavelength assignment request signal. The OLT 200 (for example, the CPU 223) refers to the wavelength management table 220, and from the entry whose serial number is not registered, the downstream wavelength information λd1 and the upstream wavelength information λu1 (upstream, The second wavelength is assigned in the downstream direction. Further, the OLT 200 (for example, the CPU 223) generates a control signal (wavelength assignment notification, second control message) 1001-1 for assigning the wavelength information λd1 and λu1, and the PON corresponding to the message transmission buffer 222 and the management wavelength λd32. It transmits to ONU300-1 with wavelength (lambda) d32 via the frame production | generation part 204-1.

  The ONU 300-1 sets its own reception wavelength to λd32 as described above, and receives the control signal 1001-1. The ONU 300-1 sets its own transmission wavelength to λu1 and the reception wavelength to λd1 based on the content of the received control signal 1001-1. For example, the CPU 323 of the ONU 300-1 stores the upstream wavelength information λu1 and the downstream wavelength information λd1 included in the received control signal in the wavelength management memory 322. Further, the reception wavelength control unit 321 sets the wavelength of the wavelength tunable filter 302 to the wavelength λd1 stored in the wavelength management memory 322. Also, the reception wavelength control unit 321 sets the wavelength of the wavelength tunable laser 313 to the wavelength λu1 stored in the wavelength management memory 322.

  Subsequently, the ONU 300-1 notifies the OLT 200 by the control signal (wavelength confirmation signal) 1002-1 that its own wavelength setting has been completed. For example, the CPU 323 of the ONU 300-1 generates the wavelength confirmation signal 1002-1 shown in FIG. 7C and transmits it to the OLT 200 by the wavelength tunable laser 313 via the message transmission buffer 310. Here, the transmission wavelength of the wavelength tunable laser 313 is set to λu1, and the wavelength confirmation signal 1002-1 is transmitted at the wavelength λu1.

  The OLT 200 receives the wavelength confirmation signal 1002-1 from the ONU 300-1. Here, the signal is received by the O / E 208-1 corresponding to the wavelength λu1. The CPU 223 registers the serial number of the ONU 300-1 in the wavelength management table 220 corresponding to the assigned wavelength (FIG. 12 (b)). As the serial number, the serial number included in the received wavelength confirmation signal and wavelength request signal can be used. In addition, the CPU 223 registers the ONU-ID in the connection management table 221. For example, the connection management table 221 is referred to based on the serial number of the ONU 300-1, and the assigned ONU-ID is registered corresponding to the corresponding serial number. Here, since the ONU-ID is “1” as registered in the wavelength management table 220, the ONU-ID corresponds to the serial number “A000 0001” of the ONU 300-1 as in the example of FIG. “1” is registered. The ONU-ID can be assigned at an appropriate timing.

  The OLT 200 (signal distribution unit 203) reads the corresponding ONU-ID in the connection management table 221 based on the label attached to the packet (user signal) received from the PSTN / Internet 20, for example, and responds to the ONU-ID. The user signal is distributed to the PON frame generation unit 204-1. The ONU-ID corresponds to the wavelength as shown in the wavelength management table, and the user signal 1003-1 is transmitted to the ONU 300-1 at the downstream wavelength λd1 assigned to the ONU 300-1. On the other hand, the ONU 300-1 transmits the user signal 1003-1 using the wavelength λu1, thereby establishing bidirectional communication.

Next, the wavelength allocation operation of the connected ONU 300-2 will be described.
Similar to the ONU 300-1, the ONU 300-2 transmits its wavelength assignment request signal 1000-2 after setting its own transmission wavelength to λu32 based on a prior agreement immediately after power-on. On the other hand, the OLT 200 constantly monitors the control signal received using the wavelength λu32, and after receiving the wavelength assignment request signal 1001-2, refers to the wavelength management table 220, and here for the # 2 from the unregistered entry For example, the downstream wavelength λd2 and the upstream wavelength λu2, which are the youngest numbers at this time, are assigned, and the control signal 1001-2 is transmitted.

  The ONU 300-2 has its reception wavelength set to λd32 and receives the control signal 1001-2. The ONU 300-2 sets its transmission wavelength to λu2 and the reception wavelength to λd2 based on the content of the received control signal 1001-2. Subsequently, the ONU 300-2 notifies the OLT 200 by the control signal 1002-2 that its own wavelength setting has been completed.

  Similar to the above, the OLT 200 registers the serial number of the ONU 300-2 in the wavelength management table 220 and registers the ONU-ID in the connection management table 221. FIG. 12C shows an example of the wavelength management table 220 in which the serial number of the ONU 300-2 is registered.

  The OLT 200 distributes the user signal provided with the connection label of the ONU 300-2 according to the corresponding ONU-ID with reference to the connection table 221. Here, it is distributed to the PON frame generator 204-2 and transmitted using the wavelength λd2. On the other hand, the ONU 300-2 transmits a user signal using the wavelength λu2, thereby establishing bidirectional communication between the OLT 200 and the ONU 300-2.

  Thereafter, wavelength setting for other ONUs connected to the OLT 200 is performed in the same manner, and the ONU 300-32 assigns wavelengths using the management wavelengths λu32 and λd32, and the same λu32 and λd32 are assigned for communication. End. FIG. 13A shows an example of a wavelength management table when all communicable wavelengths are assigned. Here, the wavelengths λd32 and λu32 are used for communication with the ONU 300-32 having the serial number “A000 0020”, but can also be used as management wavelengths.

FIG. 10 is a sequence diagram (1) when the ONU is disconnected and connected.
The operation when one ONU 300 is disconnected and another ONU 300 is connected will be described with reference to FIG. In this example, the ONU 300-1 and the ONU 300-2 are connected to and communicated with the OLT 200 (1003-1, 1003-2), and the ONU 300-32 is not connected.

  For example, when the ONU 300-2 is disconnected, the OLT 200 detects the disconnection of the ONU 300-2 because the signal reception of λu2 is interrupted. The OLT 200 changes the column of the wavelength λu2 (that is, the ONU-ID is “2”) in the wavelength management table 220 to an unregistered entry. For example, the serial number corresponding to the wavelength λu2 is deleted and unregistered. Also, the connection management table 221 is referred to based on the deleted serial number, and the corresponding ONU-ID is deleted from the connection management table 221. For example, the wavelength management table is in the state shown in FIG.

  Thereafter, when an ONU 300-2 'having another serial number is connected, the ONU 300-2' transmits its wavelength assignment request signal 1000-2 after setting its own transmission wavelength to λu32 as described above. On the other hand, the OLT 200 constantly monitors the control signal received using the wavelength λu32, and after receiving the wavelength assignment request signal 1001-2, refers to the wavelength management table 220 and sets the smallest number at this time from the unregistered entry. The downstream wavelength λd2 and the upstream wavelength λu2 are assigned as the wavelengths for # 2, and the control signal 1001-2 is transmitted. Thereafter, bidirectional communication between the ONU 300-2 'and the OLT 200 is established using λd2 and λu2 in the same sequence as in FIG.

FIG. 11 is a sequence diagram (2) when the ONU is disconnected and connected.
Next, another operation when one ONU is disconnected and another ONU is connected will be described with reference to FIG. In this example, all ONUs from ONU 300-1 to ONU 300-32 are connected and communication is being performed. The contents of the wavelength management table 220 at this time are shown in FIG.

  When the ONU 300-2 is disconnected, the OLT 200 detects that the signal reception of λu2 has been interrupted, so it detects the disconnection of the ONU 300-2 and changes the ONU # 2 column of the wavelength management table 220 to an unregistered entry as described above. To do. In this example, since the management wavelength λd32 is used together with the communication of the ONU 300-32, the wavelengths λd2 and λu2 may be set as the management wavelengths. The contents of the wavelength management table 220 at this time are shown in FIG. Also, the connection management table 221 is referred to based on the deleted serial number, and the corresponding ONU-ID is deleted from the connection management table 221.

  Here, the OLT 200 notifies the ONU 300 using the control wavelength notification signal 1004 shown in FIG. 24 that the current control wavelength (management wavelength) has been changed to λd2 and λu2 by the wavelength λd32. The OLT 200 may transmit the control wavelength notification signal 1004 a plurality of times.

  Thereafter, when an ONU 300-2 ′ having another serial number (serial number “A000 0040”) is connected, the ONU 300-2 ′ sets its own reception wavelength to a predetermined wavelength λd32 and then notifies the control wavelength. The signal 1004 is read to detect that the current control wavelength is changed to λd2 and λu2. The ONU 300-2 'transmits its wavelength assignment request signal 1000-2 in the same manner as described above after setting its own transmission wavelength to λu2. Here, the signal is transmitted at the wavelength λu2.

On the other hand, the OLT 200 constantly monitors the control signal received using the wavelength λu2, receives the wavelength assignment request signal 1001-2, refers to the wavelength management table 220, and starts from the unregistered entry with the smallest number at this time. The downstream wavelength λd2 and the upstream wavelength λu2 are assigned as the wavelengths for # 2, and the control signal 1001-2 is transmitted.
Thereafter, bidirectional communication is established by the same sequence as in FIG. Then, the content of the wavelength management table in which the wavelength is assigned to the ONU 300-2 ′ is the content shown in FIG.

2. Second embodiment (system configuration)
FIG. 14 shows a configuration example of the OLT 200 of the present embodiment.
3 differs from the configuration of FIG. 3 in that, for example, a transmission valid control unit 225 connected to the wavelength management table 220 is further provided, and the wavelength that is not registered for use in the wavelength management table 220 is not activated by the driver 205. The point is that the wavelength is not emitted. For example, a downstream wavelength driver whose serial number is not registered in the wavelength management table 220 is invalidated. Therefore, the ONU 300 can monitor the presence / absence of a signal for each downstream wavelength and know which wavelength is unused.

FIG. 15 shows a configuration example of the ONU 300 according to the present embodiment.
One difference from the configuration of FIG. 4 is that the reception power detection unit 326 is connected to the O / E 303. The CPU 323 controls the wavelength variable filter 302 via the reception wavelength control unit 321 by sequentially changing the downstream wavelength in the wavelength management memory from λd1 to λd32 at regular intervals, for example, with reference to the timer 325. In O / E, the wavelengths from λd1 to λd32 are photoelectrically converted in sequence, so that the CPU 323 can know which downstream wavelength is unused by monitoring the output of the reception power detector 326. For example, a wavelength with zero or almost zero reception power is unused.

  Another difference from the configuration of FIG. 4 is that a part of the output of the wavelength tunable laser 313 is connected to the wavelength monitoring unit 314, and the output of the wavelength monitoring unit 314 is connected to the transmission valid control unit 315 to enable the driver 312. It is a point to control. If the transmission wavelength deviates from the set wavelength due to a failure of the wavelength tunable laser 313 or the transmission wavelength control unit 320, there is a possibility of adversely affecting the upstream signal of other ONUs 300, so this failure needs to be avoided. The wavelength monitoring unit 314 monitors whether the value of the upstream wavelength in the wavelength management memory 322 and the transmission wavelength of the wavelength tunable laser 313 are not more than a predetermined range, for example. The wavelength monitoring unit 314 stops the operation of the driver 312 by the transmission effective control unit 315 when detecting the disconnection. By this operation, the upstream signal stops, and the OLT 200 that detects the stop of the upstream wavelength tries again the wavelength allocation of the ONU 300, but the ONU 300 that has a fault in wavelength control cannot perform the wavelength allocation operation at the correct wavelength, This ONU is determined to be a failure. The other configurations of the network configuration, the OLT 200, and the ONU 300 are the same as those in the first embodiment.

FIG. 16 shows an operation sequence diagram in the second embodiment.
Here, the OLT detects the presence / absence of a received signal for all wavelengths that can be used for uplink communication in the WDM-PON system, and responds to the result of the presence / absence of the received signal and the correspondence between a predetermined downstream wavelength and upstream wavelength. Based on this, the transmission of the downstream wavelength signal corresponding to the upstream wavelength with no received signal is stopped. Therefore, in the initial state where no ONU is connected, no signal is output for all downstream wavelengths. When the ONU 300-1 is connected, the ONU 300-1 detects the presence / absence of reception signals for all wavelengths that can be used for downlink communication at the time of initial startup. Here, it is detected that all wavelengths of λd1 to λd32 are unused. The ONU 300-1 selects, for example, λu1 and sets a control message (wavelength allocation request) 1000-1 for requesting λu1 and λd1 paired therewith as a wavelength allocation used for communication with the OLT 200 in the format of FIG. 7B. And transmit at wavelength λu1.

  The OLT 200 receives the control message 1000-1 at the wavelength λu1, and activates the driver 205 of λd1 corresponding to λu1 by the transmission validity control unit 225. The OLT 200 generates a control message (wavelength assignment request signal) 1001-1 for notifying wavelengths assigned to communication with the ONU 300-1 in λu1 and λd1 in the format of FIG. 7C, and transmits it using λd1. Note that the OLT 200 may assign wavelengths (for example, λu2 and λd2) different from the wavelengths λu1 and λd1 with reference to the wavelength management table 220.

  The ONU 300-1 sets its own reception wavelength to λd1 paired with λu1, and receives the control signal 1001-1. The ONU 300-1 confirms that its transmission wavelength is λu1 and the reception wavelength is λd1 based on the content of the received control signal 1001-1, and resets it. Further, the ONU 300-1 notifies the OLT 200 by the control signal (wavelength confirmation, control message) 1002-1 that its own wavelength setting has been completed.

  The OLT 200 stores, for example, the ONU serial number included in the control signal 1002-1 corresponding to the wavelengths λd1 and λu1 of the wavelength management table 220. The OLT 200 registers the ONU-ID in the connection management table. The OLT 200 transmits the user signal of the address registered as ONU # 1 in the connection table 221 by using the wavelength λd1, while the ONU 300-1 transmits the user signal by using the wavelength λu1 so as to be bidirectional. Communication is established.

  When assigning wavelengths different from the wavelengths λu1 and λd1 (for example, λu2 and λd2), similar to the first embodiment, the OLT 200 receives the control message and refers to the wavelength management table to The second downstream wavelength λd2 and the second upstream wavelength λu2 that are not used for communication with the ONU 300 are assigned to the communication with the ONU 300. Further, the OLT 200 transmits a second control message for notifying the allocated second downlink wavelength information and second uplink wavelength information to the ONU 300 using the first downlink wavelength λd1. The ONU 300 receives the second control message by the second receiver set to the first downstream wavelength, and sets the transmission wavelength of the second transmitter to the second upstream wavelength by the wavelength controller based on the second control message. And the reception wavelength of the second receiver is set to the second downstream wavelength. The ONU 300 and the OLT 200 communicate using the second downstream wavelength and the second upstream wavelength.

The OLT 200 detects the disconnection with the ONU 300 when the first upstream wavelength or the second upstream wavelength assigned to the ONU 300 is not received by the first receiver for a predetermined time. When the disconnection is detected, the transmission valid control unit invalidates the first transmitter of the first or second downstream wavelength that is paired with the first or second upstream wavelength.
In the second embodiment, since λu32 is not shared by default as in the first embodiment, the possibility of an uplink signal collision is smaller and suitable for efficient startup.

  The present invention can be used for, for example, an access network using an optical technology and an optical access system using a PON system.

10 PON
20 PSTN / Internet 100 Optical splitter 110 Main fiber 120 Branch fiber 200 OLT
300 ONU
400 Telephone 410 Personal computer 203 Signal distribution 205 Driver 206 E / O
207 WDM filter 208 O / E
220 Wavelength management table 221 Connection management table 223 CPU
224 memory 301 WDM filter 302 tunable filter 303 O / E
312 Driver 313 Wavelength tunable laser 320 Transmission wavelength control unit 321 Reception wavelength control unit 322 Wavelength management memory 323 CPU
324 Memory 325 Timer 225 Transmission effective control unit 326 Reception power detection unit 314 Wavelength monitoring unit 315 Transmission effective control unit

Claims (4)

An optical termination device, an optical splitter, and a plurality of optical network units connected to the optical termination device via an optical fiber and the optical splitter, and the optical termination device and the optical network unit are wavelength division multiplexed. In a passive optical network system for communication,
The optical terminator is:
A plurality of first transmitters having light sources having different wavelengths from each other;
A plurality of first receivers for receiving signals of a plurality of wavelengths;
A wavelength management table for managing wavelength information allocated for communication with each optical network unit for each identifier of the optical network unit;
A first control unit that receives a control message for assigning a wavelength from the optical network unit, and assigns a wavelength for communication between the optical terminal unit and the optical network unit;
A transmission valid control unit for enabling each of the plurality of first transmitters to be output by enabling or disabling only the wavelength being communicated with the optical network unit;
Each of the optical network units is
A second receiver for receiving a signal of a set wavelength;
A second transmitter for transmitting a signal of a set wavelength;
A received power detector for detecting received power at the second receiver;
A second control unit for transmitting a control message for assigning a wavelength via the second transmitter;
A wavelength control unit that variably controls the transmission wavelength of the second transmitter and the reception wavelength of the second receiver;
The second control unit of a plurality of the optical network units to which a wavelength used for communication is not assigned ,
The wavelength control unit sequentially switches the reception wavelength of the second receiver to the transmission wavelengths of the plurality of first transmitters of the optical termination device,
The reception power detection unit detects the reception power of the downlink signal from the optical termination device to the optical network unit for each wavelength, and one wavelength is not used for other communication based on the reception power . Select the first downstream wavelength,
The wavelength control unit sets the reception wavelength of the second receiver to the first downstream wavelength, and sets the transmission wavelength of the second transmitter to a first upstream wavelength that is paired with the first downstream wavelength. And
Using the first upstream wavelength, a first control message storing a first downstream wavelength and an identifier of the first upstream wavelength requesting allocation for use in communication with the optical termination device is transmitted to the optical termination device. ,
The first control unit of the optical termination device includes:
Wherein when receiving the first control message, the first downstream wavelength and a first upstream wavelength, young properly refers to the wavelength management table, a second downstream wavelength and the second upstream wavelength not used for other communication was determined assign for communication with the optical network unit in the order of arrival of said first control message,
By the effective transmission control unit, the first enable transmitter, second the optical network control messages that stores the assignment downstream wavelength and assigned assigned upstream wavelength assigned corresponding to the first downlink wave length To the unit,
The second control unit of the optical network unit confirms that the assigned downlink wavelength can be used, sets the reception wavelength of the second receiver to the assigned downlink wavelength, and transmits the transmission wavelength of the second transmitter. Is set to the assigned uplink wavelength that is paired with the assigned downlink wavelength, and the assigned uplink wavelength is used to transmit the third control message for confirming that the assigned downlink wavelength and the assigned uplink wavelength are valid. ,
The passive optical network system in which the optical network unit and the optical termination device communicate with each other using the assigned downstream wavelength and the assigned upstream wavelength .   The passive optical network system according to claim 1,
  The optical network unit that is not assigned even if a wavelength is requested due to competition between a plurality of the optical network units, detects again the reception power of the downlink signal to the optical network unit, and based on the received power, Select one wavelength that is different from the previously selected wavelength from the wavelengths not used for communication, until the wavelength is assigned from the optical termination device,
  Sequentially switching the reception wavelength of the second receiver; detecting received power to select one first downlink wavelength; setting the first downlink wavelength and the first uplink wavelength; The passive optical network system that repeats transmitting a first control message to the optical termination device.   The passive optical network system according to claim 2,
  A wavelength monitoring unit for monitoring an output wavelength range of the second transmitter;
  A transmission effective control unit for stopping the output of the second transmitter when the monitoring result of the output wavelength range deviates more than a predetermined range;
A passive optical network system that detects a failure of the optical network unit with the optical termination device. An optical termination device, an optical splitter, and a plurality of optical network units connected to the optical termination device via an optical fiber and the optical splitter, and the optical termination device and the optical network unit are wavelength division multiplexed. A wavelength allocation method in a passive optical network system for communication,
Multiple optical network units that are not assigned wavelengths for communication
The reception wavelength of the receiver of the optical network unit is sequentially switched to each transmission wavelength of the plurality of transmitters of the optical termination device, and for each wavelength, the reception power of the downstream signal from the optical termination device to the optical network unit is detected,
Select one first downstream wavelength from wavelengths not used for other communications based on the received power,
The reception wavelength of the receiver of the optical network unit is set to the obtained first downstream wavelength, and the transmission wavelength of the transmitter of the optical network unit is set to the first upstream wavelength paired with the first downstream wavelength;
Using the first upstream wavelength, a first control message storing an identifier of the first downstream wavelength and the first upstream wavelength requesting allocation for use in communication with the optical termination device is transmitted to the optical termination device,
The optical terminator is
When receiving the first control message, the first downstream wavelength and a first upstream wave length, or a wavelength of managing wavelength information assigned for communication with the optical network units for each identifier of the optical network units by referring to the management table to determine the assign in the order of arrival of said first control message a second downstream wavelength and the second upstream wavelength not used for other communications to communicate with the optical network unit,
Send Enable transmitter optical terminal device corresponding to the first downlink wave length, the second control message containing the allocation downstream wavelength and assigned assigned upstream wavelength assigned to the optical network unit,
The optical network unit confirms that the assigned downlink wavelength can be used, sets the reception wavelength of the receiver of the optical network unit to the assigned downlink wavelength, and sets the transmission wavelength of the transmitter of the optical network unit to the assigned downlink wavelength. A third control message for confirming that the assigned downlink wavelength and the assigned uplink wavelength are valid using the assigned uplink wavelength,
The wavelength allocation method in which an optical network unit and an optical termination device communicate with each other by the allocated downstream wavelength and the allocated upstream wavelength , or by the second downstream wavelength and the second upstream wavelength.

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