JP5761415B1 - Subscriber side device registration method - Google Patents

Abstract

In registering a subscriber-side device by sweeping the transmission wavelength of a variable wavelength filter and the attenuation amount of a variable attenuator, the number of times of changing the attenuation amount of the variable attenuator is minimized, and a low-speed response is achieved. A method is provided that can be implemented with a variable attenuator. An optimum value of attenuation in a variable attenuator is acquired for a signal transmitted by any of a plurality of station side devices. After obtaining the optimum value, the transmission wavelength of the variable wavelength filter is changed and the discovery gate is received. [Selection] Figure 5

Description

  The present invention relates to a subscriber-side device registration method in a network composed of a receiving station having a plurality of station-side devices and one or a plurality of subscriber-side devices.

  A communication network that connects a building (station) owned by a communication carrier and a subscriber's home is called an access network. In response to the recent increase in communication capacity, optical access networks that enable transmission of an enormous amount of information by using optical communication are becoming mainstream in access networks.

  As one form of the optical access network, there is a passive optical network (PON: Passive Optical Network). The PON includes one station side device (OLT: Optical Line Terminal) provided in the station, a plurality of subscriber side devices (ONU: Optical Network Unit) provided in each subscriber's house, and an optical coupler. Is done. The OLT and ONU and the optical coupler are connected by an optical fiber.

  A single-core optical fiber is used for connection between the OLT and the optical coupler. This single-core optical fiber is branched by an optical coupler and shared by a plurality of ONUs. The optical coupler is an inexpensive passive element. Thus, PON is excellent in economic efficiency and easy to maintain. For this reason, the introduction of PON is progressing rapidly.

  In the PON, signals transmitted from each ONU to the OLT (hereinafter also referred to as upstream optical signals) are combined by an optical coupler and transmitted to the OLT. On the other hand, a signal sent from the OLT to each ONU (hereinafter also referred to as a downstream optical signal) is demultiplexed by an optical coupler and transmitted to each ONU. In order to prevent interference between the upstream optical signal and downstream optical signal, different wavelengths are assigned to the upstream optical signal and downstream optical signal, respectively.

  In PON, various multiplexing techniques are used. The multiplexing technology used in the PON includes time division multiplexing (TDM) technology in which a short interval on the time axis is assigned to each subscriber, wavelength division multiplexing (WDM) in which different wavelengths are assigned to each subscriber (WDM: Wave Division Division Multiplex). And code division multiplexing (CDM) technology that assigns different codes to each subscriber. Among these multiplexing techniques, TDM-PON using TDM is currently most widely used. In TDM-PON, TDMA (Time Division Multiple Access) is used. TDMA is a technique in which the OLT manages the transmission timing of each ONU so that upstream optical signals from different ONUs do not collide with each other.

Among the PON systems, those using the Ethernet (registered trademark) technology are referred to as Ethernet (registered trademark) -PON, and those using the Gigabit (1 × 10 ⁹ bits / sec) Ethernet (registered trademark) technology are used. -Called PON. GE-PON is standardized by IEEE 802.3ah.

  In the GE-PON system, in order to perform communication between the OLT and the ONU, it is necessary to register the ONU in the OLT. In the GE-PON system, since a plurality of ONUs are connected to one OLT, new ONU registration is performed without affecting the communication between other registered ONUs and the OLT. There is a need. For this reason, IEEE 802.3ah (hereinafter referred to as a standard) defines a procedure (hereinafter referred to as a discovery sequence) in which an unregistered ONU is detected and registered in the OLT.

  The OLT broadcasts discovery gates periodically. The discovery gate is transmitted to all ONUs regardless of whether or not the ONU is registered. Note that a period in which the OLT transmits a discovery gate is referred to as a discovery period. The ONU newly connected to the PON system receives the discovery gate periodically when the power is turned on and the signal can be received.

  When an unregistered ONU receives a discovery gate, it transmits a register request for requesting registration to the OLT. The register request includes a MAC address as an individual identification number of each ONU.

  On the other hand, in OLT, a discovery window is set. The OLT waits for receipt of a register request during the time this window is open.

  The OLT recognizes the ONU MAC address by receiving the register request. The OLT sends a register to the ONU having the recognized MAC address. The register includes a link number (LLID) in the PON system.

  Further, following the transmission of the register, the OLT notifies the transmission band and the transmission timing, and sends a gate permitting the transmission of the upstream optical signal to the ONU.

  The ONU that has received the gate transmits a register ACK (ACK) to the OLT. When the OLT receives the register ACK, the ONU registration is completed. That is, the discovery sequence ends.

  After the ONU is registered, normal communication between the OLT and the ONU is performed.

  By the way, a PON system using both TDM and WDM (hereinafter also referred to as TWDM-PON) has been proposed. In TWDM-PON, for example, a receiving station has a plurality of OLTs.

  In TWDM-PON, a different transmission wavelength is assigned to each OLT. Each OLT transmits a downstream optical signal having the assigned wavelength. On the other hand, the ONU transmits the upstream optical signal at the transmission wavelength and transmission timing notified by the downstream optical signal from the OLT. Each ONU is assigned a different transmission timing. In TWDM-PON, the ONUs to be managed are distributed and managed by a plurality of OLTs, and the service band provided to the subscriber can be increased by reducing the ONUs managed by one OLT.

  Here, in TWDM-PON, an ONU may be registered in one of a plurality of OLTs. As already described, in the TWDM-PON, the ONU performs communication at a wavelength corresponding to the OLT, and therefore it is preferable that the wavelength that can be transmitted and received is variable.

  Therefore, in TWDM-PON, there is a configuration in which a variable wavelength filter (T-FL) is provided in the ONU (see, for example, Patent Document 1).

  In this configuration, the unregistered ONU sweeps the transmission wavelength of the variable wavelength filter and waits for the discovery gate.

  When an unregistered ONU receives a downstream optical signal, it measures its optical power. When the measured optical power is smaller than a certain value, the transmission wavelength of the variable wavelength filter is changed and a different transmission wavelength is set.

  If the measured optical power is greater than or equal to a certain value, the unregistered ONU determines whether the downstream optical signal is a discovery gate. If the discovery gate is detected, a discovery sequence is performed through the above-described processes. On the other hand, if no discovery gate is detected, it waits for a certain time. If the discovery gate is not received during this fixed time (that is, a timeout occurs), the transmission wavelength of the variable wavelength filter is changed again, and a different transmission wavelength is set.

  In TWDM-PON, an optical transmitter is caused to emit light with higher light intensity, and communication with an ONU located at a location more than a conventional transmission distance is enabled. However, if the light is emitted with a higher light intensity, the light intensity input to the ONU located at a short distance is too high, and the receiver may break down. For this reason, a technique has been reported in which a variable optical attenuator (VOA) is inserted in front of a receiver so that a downstream optical signal is input with an optimal optical intensity corresponding to the transmission distance (for example, a patent). Reference 2).

JP 2011-004270 A JP 2012-019264 A

  When the above-described discovery sequence is performed on the configuration described in Patent Document 2, since the ONU does not know the timing, wavelength, and light intensity of the discovery gate, the center wavelength sweep of the T-FL and the attenuation of the VOA A volume sweep is required. The discovery gate can be received only after the center wavelength of the T-FL is set to the wavelength of the discovery gate and the attenuation amount of the VOA is adjusted to an optimum value.

  As a T-FL and VOA sweeping method for this purpose, the T-FL is fixed at the wavelength 1, and the attenuation amount of the VOA is gradually decreased from the maximum so that the light intensity in the power monitor falls within the dynamic range of the receiver. A method of adjusting to the above can be considered. In this case, if the light intensity is not detected by the power monitor even after the sweep of the VOA is completed, it is determined that a downstream signal with that wavelength is not transmitted, and the shift is made to the next wavelength. In addition, if the discovery gate is not received even after waiting for a fixed time in a state where the downstream signal is detected and the light intensity is further optimized, it is determined that the discovery gate is not transmitted at that wavelength, Shift to the next wavelength. In this case, after the wavelength shift, the attenuation amount of the VOA is gradually decreased again from the maximum.

  However, in this method, since the number of times of changing the attenuation amount of the VOA is increased, in the case of the VOA having a low-speed response, the time until the minimum light intensity is set becomes a problem. On the other hand, since a VOA with high-speed response is expensive, there is a problem of cost when considering application to an optical access network.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is a subscriber-side device registration method, which minimizes the number of times of changing the attenuation amount of a VOA and has a low-speed response. It is intended to provide a T-FL and VOA sweeping method that can be implemented with other VOAs.

In order to achieve the above-described object, a subscriber-side device registration method of the present invention includes a receiving station having a plurality of station-side devices, a variable attenuator, a variable wavelength filter, a light intensity detector, and an attenuation / transmission amount. A plurality of subscriber devices connected to the station side device via an optical transmission line, each of the plurality of station side devices being connected to the subscriber device; It transmits the optical signal, the plurality of subscriber units, relative to the central terminal, a network for transmitting upstream optical signals at different transmission timings, a method of registering an unregistered subscriber device, unregistered The following steps are performed in the attenuation / transmission wavelength control unit of the subscriber unit .

First, in the first process, the attenuation of the variable attenuator is maximized. Next, in a second process performed after the first process, the transmission wavelength of the variable wavelength filter is set to one of the transmission wavelengths of the plurality of station-side devices. Next, in a third process performed after the second process, the attenuation of the variable attenuator is reduced. Next, in a fourth process performed after the third process, it is determined whether or not the light intensity is detected by the light intensity detector.
If the light intensity is not detected as a result of the determination in the fourth process, it is determined in the fifth process whether or not the attenuation amount of the variable attenuator is minimum. If the light intensity is detected as a result of the determination in the fourth process, the attenuation amount of the variable attenuator is received in the subsequent stage based on the detection result in the light intensity detector in the sixth process. Set to the optimum value within the dynamic range of the instrument.
Next, in a seventh process performed after the sixth process, reception of the discovery gate is awaited. Next, in the eighth process performed after the seventh process, it is determined whether or not the discovery gate is received.
If the discovery gate is received as a result of the determination in the eighth step, the transmission wavelength of the variable wavelength filter and the attenuation amount of the variable attenuator are fixed in the ninth step. If the result of determination in the eighth step is that a discovery gate has not been received, it is determined in the tenth step whether or not a standby time has elapsed.
If the standby time has passed as a result of the determination in the tenth process, the transmission wavelength of the variable wavelength filter is changed to another wavelength in the eleventh process. Next, in the twelfth process performed after the eleventh process, it is determined whether or not the input light intensity is detected.
Here, when the attenuation amount is the minimum as a result of the determination in the fifth process, the first process is performed. When the attenuation amount is not the minimum as the result of the determination in the fifth process, the third process is performed. Do the process.
If the waiting time has not elapsed as a result of the determination in the tenth process, the seventh process is performed. If the input light intensity is detected as a result of the determination in the twelfth process, Step 7 is performed, and if not detected, the eleventh step is performed.

  According to the subscriber side apparatus registration method of the present invention, it is possible to reduce the time until the discovery gate is received as compared with the conventional registration method without using a costly and fast response VOA.

It is a schematic diagram of TWDM-PON. It is a schematic diagram of ONU. It is a figure which shows a discovery sequence. It is a processing flowchart for demonstrating the 1st registration method. It is a schematic diagram which shows the image of operation | movement of a 1st registration method. It is a schematic diagram which shows the image of operation | movement of the conventional registration method. It is a processing flowchart for demonstrating the 2nd registration method. It is a schematic diagram which shows the image of operation | movement of the 2nd registration method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the shape, size, and arrangement relationship of each component are merely schematically shown to the extent that the present invention can be understood. In the following, a preferred configuration example of the present invention will be described. However, the material and numerical conditions of each component are merely preferred examples. Therefore, the present invention is not limited to the following embodiments, and many changes or modifications that can achieve the effects of the present invention can be made without departing from the scope of the configuration of the present invention.

(TWDM-PON)
The subscriber side device registration method according to the present invention is used in TWDM-PON. First, the configuration of the TWDM-PON will be described with reference to FIG. FIG. 1 is a schematic diagram of a TWDM-PON.

  The TWDM-PON 10 includes a plurality of OLTs 200, a plurality of ONUs 400, and a plurality of optical couplers 300. The plurality of OLTs 200 are connected to one optical coupler 300 via an optical fiber via a transceiver (TRx) 210, respectively. Each of the plurality of ONUs 400 is connected to the optical coupler 300 via an optical fiber. The optical couplers 300 are also connected by optical fibers.

  In the TWDM-PON 10, different transmission wavelengths are assigned to the respective OLTs 200. Each OLT 200 transmits a downstream optical signal having the assigned wavelength. On the other hand, the ONU 400 transmits the upstream optical signal at the transmission wavelength and transmission timing notified from the OLT 200 by the downstream optical signal. Each ONU 400 is assigned a different transmission timing.

  The plurality of OLTs 200 are provided in the accommodating station 100 and are connected to a higher level network by a switching element (L2SW) 120.

  The switching element 120 sets a communication path between the upper network and each OLT 200. Based on the transmission plan notified from the OLT control unit 110, the switching element 120 distributes and transmits the downlink data signal to each OLT 200 and transmits the uplink data signal transmitted from each OLT 200 to the upper network. In addition, the OLT control unit 110 is notified of information such as the destination and traffic of the downlink data signal transmitted from the host network.

  The OLT control unit 110 included in the accommodating station 100 manages the ONU 400 (PON link information) that has established the PON link. The OLT control unit 110 stores the PON link information in a storage unit (not shown) such as a RAM (Random Access Memory) so that it can be read and rewritten. Then, the OLT control unit 110 creates a transmission plan based on information such as destination and traffic received from the switching element 120 and PON link information. The OLT control unit 110 notifies the transmission plan to the switching element 120 and each OLT 200.

  Further, the OLT control unit 110 generates a wavelength setting signal that notifies each OLT of the wavelength of the downstream optical signal. The wavelength setting signal is sent to the OLT 200. As already described, in the TWDM-PON 10, communication is performed between the OLT 200 and the ONU 400 at a specific wavelength. Therefore, the OLT control unit 110 causes each OLT 200 to set downstream optical signals having different wavelengths.

  Further, the OLT control unit 110 determines the OLT 200 that performs the discovery sequence based on the transmission plan.

  In performing the subscriber-side device registration method according to the present invention, any suitable conventionally known OLT 200 can be used.

(ONU)
With reference to FIG. 2, an ONU according to an embodiment of the present invention will be described. FIG. 2 is a schematic diagram of an ONU.

  The ONU 400 includes a WDM (Wavelength Division Multiplex) filter 410, a wavelength tunable transmitter (wavelength tunable Tx) 420, an ONU MAC (Media Access Control) 430, a UNI (User network Interface) 440, a variable attenuator (VO) 450, a variable attenuator (VO), and a variable attenuator (VO) 450. A filter (T-FL) 460, a receiver (Rx) 470, and a VOA / T-FL control unit 480 are provided.

  The WDM filter 410 multiplexes and demultiplexes the upstream transmission wavelength band and the downstream transmission wavelength band, and transmits the optical signal (upstream signal) in the upstream transmission wavelength band received from the wavelength variable Tx 420 toward the OLT. The optical signal (downstream signal) in the downstream transmission wavelength band received from the OLT is sent to the VOA 450.

  The wavelength variable Tx 420 generates an uplink signal with a wavelength corresponding to the transmission destination OLT, and sends it to the WDM filter 410. The wavelength of this upstream signal is instructed from the ONU MAC 430.

  The ONU MAC 430 has an MPCP (Multipoint Control Protocol) function for executing control for establishing communication with the OLT. The ONU MAC 430 performs reception determination of the discovery gate in the discovery sequence.

  The UNI 440 is an interface for connection with a user terminal, and for example, an Ethernet (registered trademark) PHY or the like is mounted thereon.

  The VOA 450 attenuates the input light intensity and outputs the light intensity. The attenuation amount of the light intensity can be changed. This VOA is inserted immediately after the WDM filter 410 in order to prevent failure of a subsequent device due to input of light with high light intensity.

  The T-FL 460 is a wavelength filter that transmits light having a predetermined transmission wavelength, and the transmission wavelength can be changed. This T-FL 460 is inserted in the subsequent stage of the VOA 450.

  The Rx 470 is inserted after the T-FL 460 and sends a signal received via the VOA 450 and the T-FL 460 to the user terminal via the ONU MAC 430 and the UNI 440.

  The output of the T-FL 460 is branched into two, one being sent to the Rx 470 and the other being sent to the VOA / T-FL control unit 480. Here, the ratio of the signal strength sent to the Rx 470 and the signal strength sent to the VOA / T-FL control unit 480 is 10: 1.

  The VOA / T-FL control unit 480 includes a power monitor 482 as a light intensity detector, a current-voltage (IV) converter 484, a log amplifier 486, an analog-to-digital converter (ADC) 488, and a control. A circuit 490 is provided.

  The power monitor 482 measures the input light intensity that is the output of the T-FL 460 and outputs the result as a current signal. The IV converter 484 converts the current signal output from the power monitor 482 into a voltage signal. This voltage signal is amplified to an appropriate voltage level by the log amplifier 486, converted to a digital signal by the ADC 488, and sent to the control circuit 490.

  The control circuit 490 adjusts the attenuation amount of the VOA 450 according to the signal indicating the input light intensity. The control circuit 490 controls the wavelength of the T-FL 460. The change of the attenuation amount of the VOA 450 and the change of the transmission wavelength of the T-FL 460 are performed by an instruction of the control circuit 490. The control circuit 490 is connected to the ONU MAC 430 and can receive the discovery gate reception determination result and other control signal information from the ONU MAC 430. This control circuit 490 can be realized using a microcomputer or the like.

  A method of changing the attenuation amount of the VOA 450 and changing the transmission wavelength of the T-FL 460 in the control circuit 490 will be described later.

(Discovery sequence)
A discovery sequence used in the present invention will be described with reference to FIG. FIG. 3 is a diagram showing a discovery sequence defined in IEEE 802.3av.

  First, the OLT multicasts a discovery gate to all ONUs. The discovery gate includes a transmission timing of a signal (Register_REQ) indicating a registration request for an unregistered ONU.

  The unregistered ONU that has received the discovery gate transmits Register_REQ to the OLT according to the instruction of the discovery gate. An already registered ONU ignores this discovery gate.

  After transmitting the discovery gate, the OLT temporarily stops receiving the uplink data signal and receives register_REQ. This time for stopping the uplink data signal is called a discovery window. The OLT transmits an individual ID (LLID: Logical Link ID) to the ONU that has transmitted Register_REQ during this discovery window using a Register signal. Thereafter, an ACK reply Gate is transmitted to the ONU that transmitted the Register signal.

  The ONU that has received the Register signal sets the assigned LLID in itself and transmits Register_ACK to the OLT according to the instruction of Gate.

  When the OLT receives Register_ACK, the discovery sequence is completed.

  This discovery sequence is periodically performed, and the presence or absence of unregistered ONUs is constantly monitored.

(First registration method)
Here, in TWDM-PON, it is assumed that one of a plurality of OLTs performs a discovery sequence. In this case, each ONU needs to set the VOA and T-FL so that the signal of the wavelength and light intensity from the OLT that performs the discovery sequence can be received. In the first registration method, first, the attenuation amount of the VOA 450 is swept to obtain the optimum value of the attenuation amount, and after obtaining the optimum value, the transmission wavelength of the T-FL 460 is swept to perform the discovery gate. Receive. Thereafter, the discovery sequence and normal communication are performed using the attenuation amount and transmission wavelength received by the discovery gate.

  Details of the first registration method will be described with reference to FIG. FIG. 4 is a processing flowchart for explaining the first registration method. This process is performed by the control circuit 490 of the ONU.

  First, in S1, the attenuation amount of the VOA 450 is set to the maximum.

  Next, in S2, the transmission wavelength of the T-FL is changed to one of a plurality of transmission wavelengths of the OLT.

  Next, in S3, the attenuation amount of the VOA 450 is decreased. That is, the output intensity of the VOA 450 is increased. The amount of change in the attenuation amount of the VOA 450 is determined by the relationship (attenuation characteristic) between the applied voltage of the VOA 450 and the attenuation amount.

  After reducing the attenuation amount of the VOA 450, in S4, it is determined whether or not the light intensity of the input light is detected from the output of the power monitor 482.

  If the light intensity is not detected as a result of the determination in S4 (No), it is determined in S5 whether or not the attenuation amount of the VOA 450 is minimum. As a result of the determination in S5, if the attenuation is not minimum (No), the attenuation of the VOA 450 is decreased again in S3, and the determination in S4 is performed.

  The process of S3 to S5 is repeated until the input light intensity is detected at the wavelength set in S2, and the attenuation amount of the VOA 450 is decreased. As a result of repeating the steps S3 to S5, when the attenuation amount of the VOA 450 is minimized in the determination in S5 (Yes), the step S1 is performed again. That is, after setting the attenuation amount of the VOA 450 to the maximum, the transmission wavelength of the T-FL 460 is changed to another wavelength, and the processes of S3 to S5 are performed.

  When the OLT that performs transmission at the wavelength set in S2 is in the sleep state, the attenuation amount of the VOA 450 may be minimized in the determination in S5. On the other hand, when the OLT that performs transmission at the wavelength set in S2 is in an active state and performs communication, the OLT transmits a downstream optical signal addressed to another ONU at the wavelength set in S2. . Therefore, the intensity of the downstream optical signal from the OLT can be detected in S4 by repeating the steps S3 to S5 and adjusting the attenuation amount of the VOA 450.

  If the light intensity is detected as a result of the determination in S4 (Yes), the process of S6 is subsequently performed. In the process of S6, based on the detection result of the power monitor 482, the attenuation amount of the VOA 450 is set to an optimum value within the dynamic range of the subsequent receiver.

  Thereafter, in S7, the reception of the discovery gate is awaited. In S8, it is determined whether or not the discovery gate has been received.

  If the result of determination in S8 is that a discovery gate has been received (Yes), after fixing the T-FL460 wavelength and VOA 450 attenuation in S9, the same discovery sequence as before is performed to complete the registration process. To do.

  If the result of determination in S8 is that a discovery gate has not been received (No), it is determined in S10 whether or not a standby time has elapsed. This standby time is set according to the discovery period and the like.

  As a result of the determination in S10, if the standby time has not elapsed (No), S7, S8, and S10 are performed again. S7, S8 and S10 are repeated until the standby time has elapsed.

  As a result of the determination in S10, if the standby time has elapsed (Yes), it is possible that the OLT that performs transmission at the wavelength set in S2 transmits but does not perform the discovery sequence.

  In this case, after changing the transmission wavelength of the T-FL 460 to another wavelength in S11, it is determined whether or not the input light intensity is detected in S12. S11 and S12 are performed in the same manner as S2 and S4 described above. If the input light intensity is detected in S12 (Yes), S7 is performed, and if not detected (No), S11 is performed.

  The effect of the first registration method will be described with reference to FIGS. FIG. 5 is a schematic diagram showing an image of the operation of this registration method. FIG. 6 is a schematic diagram showing an image of the operation of the conventional registration method.

  As shown in FIG. 5, in this registration method, first, the process of S1 to S6 is performed at the wavelength 1, and after determining the VOA attenuation, the process of S7 to S12 is performed. In S7 to S12, only the transmission wavelength of the T-FL is changed while the attenuation amount of the VOA is fixed. As a result, the number of changes in the attenuation amount of the VOA can be suppressed.

  On the other hand, in the conventional method shown in FIG. 6, the attenuation amount of the VOA is changed for each wavelength until the discovery gate is received.

  As described above, according to the first registration method, it is possible to reduce the time until the discovery gate is received as compared with the conventional registration method without using a costly and fast response VOA.

(Second registration method)
The second registration method will be described with reference to FIGS. FIG. 7 is a processing flowchart for explaining the second registration method. This process is performed by the control circuit 490 of the ONU. FIG. 8 is a schematic diagram showing an image of the operation of the second registration method.

  The second registration method is different from the first registration method in that when the input light intensity is detected in S12 (Yes), S7 is performed after the VOA attenuation amount is adjusted to the optimum value in S13. Since the other processes are the same as those of the first registration method, a duplicate description is omitted.

  The light intensity received by the ONU may differ depending on the wavelength due to a difference in loss due to the wavelength when transmitting an optical signal from the OLT to the ONU. In this case, the optimum attenuation value set at a certain wavelength is not necessarily optimum at another wavelength. Therefore, in this second registration method, after the transmission wavelength is changed and the light intensity is detected in S11 and S12, the attenuation amount of the VOA is set to the optimum value at that wavelength.

  According to the second registration method, even when the received light intensity has wavelength dependency, the attenuation amount of the VOA can be set to an optimum value without significantly increasing the processing time.

10 TWDM-PON
100 accommodation station 110 OLT control unit 200 station side device (OLT)
210 Transceiver (TRx)
300 Optical coupler 400 Subscriber side equipment (ONU)
410 WDM filter 420 Tunable wavelength transmitter (tunable wavelength Tx)
430 ONU MAC
440 UNI
450 Variable Attenuator (VOA)
460 Variable wavelength filter (T-FL)
470 Receiver (Rx)
480 VOA / T-FL control unit 482 power monitor 484 current-voltage (IV) converter 486 log amplifier 488 analog-digital converter (ADC)
490 Control circuit

Claims (2)

A containment station having a plurality of station side devices;
A variable attenuator, a variable wavelength filter, a light intensity detector, and an attenuation amount / transmission wavelength control unit, including a plurality of subscriber devices connected to the station side device via an optical transmission line. ,
The plurality of station side devices transmit downstream optical signals having different wavelengths to the subscriber device,
The plurality of subscriber devices is a method of registering unregistered subscriber devices in a network that transmits upstream optical signals at different transmission timings to the station side device,
Performed by the attenuation / transmission wavelength control unit of the unregistered subscriber device,
A first step of maximizing the attenuation of the variable attenuator;
A second step performed after the first step to set the transmission wavelength of the variable wavelength filter to any of the transmission wavelengths of the plurality of station side devices;
A third step performed after the second step to reduce the attenuation of the variable attenuator;
A fourth step performed after the third step to determine whether or not the light intensity is detected by the light intensity detector;
As a result of the determination in the fourth process, a fifth process is performed when the light attenuation is not detected, and it is determined whether or not the amount of attenuation of the variable attenuator is minimum;
Based on the detection result of the light intensity detector, which is performed when the light intensity is detected as a result of the determination in the fourth process, the attenuation amount of the variable attenuator is changed to the dynamic range of the subsequent receiver. A sixth process of setting the optimal value of
A seventh step of waiting for reception of a discovery gate, which is performed after the sixth step;
An eighth step of determining whether or not a discovery gate is received, which is performed after the seventh step;
A ninth step of fixing the transmission wavelength of the variable wavelength filter and the attenuation amount of the variable attenuator, which is performed when a discovery gate is received as a result of the determination in the eighth step;
As a result of the determination in the eighth step, a tenth step for determining whether or not a standby time has elapsed, which is performed when a discovery gate has not been received,
As a result of the determination in the tenth process, an eleventh process is performed when the standby time has elapsed, and the transmission wavelength of the variable wavelength filter is changed to another wavelength;
A twelfth step for determining whether or not the input light intensity is detected, which is performed after the eleventh step,
As a result of the determination in the fifth process, when the attenuation is minimum, the first process is performed,
As a result of the determination in the fifth process, when the attenuation is not minimum, the third process is performed,
As a result of the determination in the tenth process, when the standby time has not elapsed, the seventh process is performed,
If the input light intensity is detected as a result of the determination in the twelfth step, the seventh step is performed; if not, the eleventh step is performed. Registration method. When the input light intensity is detected in the twelfth process, the attenuation amount of the variable attenuator is adjusted to the optimum value at the transmission wavelength after being changed in the eleventh process, and then the seventh The subscriber side apparatus registration method according to claim 1 , wherein the process is performed.

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