WO2013128489A1

WO2013128489A1 - Onu and control method

Info

Publication number: WO2013128489A1
Application number: PCT/JP2012/001381
Authority: WO
Inventors: 英哲井川
Original assignee: 三菱電機株式会社
Priority date: 2012-02-29
Filing date: 2012-02-29
Publication date: 2013-09-06

Abstract

This optical network unit (ONU) is provided with: a MAC section (6) which outputs a power-saving control signal (14) for causing an output destination to enter a power saving mode and a digital control signal (15) specifying at least one circuit block in an optical transceiver (5) as an output destination; and a logic control section (55) which outputs the power-saving control signal (14) from the MAC section (6) to the output destination specified by the digital control signal (15).

Description

ONU and control method

The present invention has a power saving function (low power consumption function) for an optical transmitter / receiver incorporated in an ONU (Optical Network Unit: subscriber-side terminating device) constituting a PON system (Passive Optical Network System) in an optical transmission system. The present invention relates to an ONU and a control method.

An ONU constituting the PON system includes an optical transceiver that converts an electrical signal into an optical signal and transmits the optical signal, receives the optical signal, and converts it into an electrical signal. The ONU has a function (power saving function) for stopping power consumption by stopping a part of the operation of the optical transceiver when not needed.
In this power saving function, a method of stopping a part of the operation of the optical transceiver when data is not transmitted is generally used. At this time, it is necessary to receive a control signal for stopping them from the host side in accordance with a circuit block (for example, a transmission circuit, a reception circuit, a transmission / reception circuit, etc.) that stops the operation in the optical transceiver.

As described above, in the power save function of the optical transceiver built in the conventional ONU, it is necessary to receive a control signal from the host for each type of power save (circuit block to be stopped). For this reason, when several power saving functions are implemented in the ONU, there is a problem that a plurality of control signals are required. In particular, in the case of optical transceivers compliant with standards such as SFP + (Small Form-Factor Pluggable Plus) and XFP (10 Gigabit Small Form-Factor Pluggable), the interface and pin assignment with the host side are determined, so power saving The control signal for realizing can be assigned only about 1 pin at most. Therefore, it is necessary to determine a power save mode to be mounted in advance, and there is a problem that it is difficult to dynamically switch the power save mode.

The present invention has been made to solve the above-described problems, and an object thereof is to provide an ONU capable of realizing a plurality of power save modes without using a plurality of control signals.

The ONU according to the present invention is a control signal for outputting a power saving control signal for causing the output destination to perform power saving, and a digital control signal for designating at least one of the circuit blocks in the optical transceiver as the output destination. An output unit and an output destination selection unit that outputs a power save control signal from the control signal output unit to an output destination specified by the digital control signal are provided.

According to the present invention, since it is configured as described above, the power save mode can be dynamically switched using an existing digital control line, so that a plurality of power save modes can be realized with one control signal. Therefore, low power consumption can be achieved.

It is a figure which shows the whole structure of the PON system which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of ONU which concerns on Embodiment 1 of this invention. It is a figure which shows the circuit structure of the optical transmitter-receiver which concerns on Embodiment 1 of this invention. It is a figure which shows another circuit structure of the optical transmitter-receiver which concerns on Embodiment 1 of this invention. The concept of the present invention and low power consumption are illustrated in time series. It is a sequence diagram which shows an example of the power save mode switching control (OLT initiative) by the PON system which concerns on Embodiment 1 of this invention. It is a sequence diagram which shows an example of the power save mode switching control (ONU initiative) by the PON system which concerns on Embodiment 1 of this invention. It is a figure which shows the circuit structure of the optical transmitter-receiver which concerns on Embodiment 2 of this invention. It is a figure which shows the circuit structure of the optical transmitter-receiver which concerns on Embodiment 3 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
1 is a diagram showing an overall configuration of a PON system according to Embodiment 1 of the present invention.
As shown in FIG. 1, the PON system includes an OLT 1 that is a station-side terminal device and a plurality of ONUs 2 (n units of ONUs # 1 to #n in FIG. 1) that are optical fibers. 3 and the star coupler 4.

In data communication in this PON system, in the downstream direction, the OLT 1 continuously transmits data to all the ONUs 2, and each ONU 2 selects and receives only the data addressed to itself. On the other hand, in the upstream direction, the ONU 2 intermittently transmits data (burst transmission) to the OLT 1 during communication. Data from each ONU 2 is transmitted by time division multiplexing (TDM) in accordance with the communication schedule set by the OLT 1.

Next, the configuration of the ONU 2 will be described with reference to FIG.
The ONU 2 includes an optical transceiver 5 and a MAC unit (Media Access Control Large Scale Integration: MAC LSI) 6 as shown in FIG.

The optical transceiver 5 converts the electrical signal from the MAC unit 6 into an optical signal and transmits it to the OLT 1, receives the optical signal from the OLT 1, converts it into an electrical signal, and outputs it to the MAC unit 6. The detailed configuration of the optical transceiver 5 will be described later.

The MAC unit 6 performs data transmission / reception with the user side terminal (UNI side) as a user side interface and also performs data transmission / reception with the optical transceiver 5. The MAC unit 6 also has a function of performing transmission timing control of the transmission circuit unit 52 in the optical transceiver 5 based on the communication schedule by the OLT 1.
Further, the MAC unit 6 also has a function of power saving a part of the optical transceiver 5 based on a communication schedule by the OLT 1. At this time, the MAC unit (control signal output unit) 6 includes a control signal (power save control signal 14) for causing the output destination to perform power saving, and a circuit block in the optical transceiver 5 as an output destination of the control signal. The control signal (digital control signal 15) for designating or switching the power save mode is output to the optical transceiver 5. For the output of the digital control signal 15, a digital control line normally prepared for DDM (Digital Diagnostics Monitoring) or the like is used.

Next, the configuration of the optical transceiver 5 will be described with reference to FIG.
As shown in FIG. 3, the optical transceiver 5 includes a card edge connector 51, a transmission circuit unit 52, an optical module 53, a reception circuit unit 54, and a logic control unit (output destination selection unit) 55.

The card edge connector 51 connects between each circuit block in the optical transceiver 5 and the MAC unit 6, and various data (transmission main signal 11, burst control signal 12, reception main signal 13, power save control signal 14 and The digital control signal 15) is transmitted and received. Here, the transmission main signal 11 and the burst control signal 12 output from the MAC unit 6 are output to the LD driver 521 of the transmission circuit unit 52. In addition, the reception main signal 13 output from the reception circuit unit 54 is output to the MAC unit 6. The power save control signal 14 and the digital control signal 15 output from the MAC unit 6 are output to the logic control unit 55. The digital control signal 15 is also output to the transmission circuit unit 52 and the reception circuit unit 54 via the logic control unit 55.

The transmission circuit unit 52 converts the electrical signal (transmission main signal 11) into an optical signal using the optical module 53 at the transmission timing specified by the burst control signal 12 output from the MAC unit 6 via the card edge connector 51. The data is converted and transmitted to the OLT 1. The transmission circuit unit 52 includes an LD (Laser Diode) driver 521 having a laser driving unit 522. The laser drive unit 522 drives the light emitting element 532 of the optical module 53.

The optical module 53 converts the electrical signal (transmission main signal 11) from the MAC unit 6 into an optical signal and transmits it to the OLT 1 under the control of the transmission circuit unit 52. The optical module 53 also has a function of receiving an optical signal from the OLT 1, converting it into an electrical signal, and outputting it to the receiving circuit unit 54. This optical module 53 is driven by a WDM (Wavelength Division Multiplex) filter 531 that multiplexes and demultiplexes optical signals of transmission wavelength / reception wavelength and a laser drive unit 522 to convert an electric signal (transmission main signal 11) into an optical signal. And a light receiving element 533 for converting an optical signal into an electric signal.

The receiving circuit unit 54 converts the electric signal (current signal) from the optical module 53 into a voltage signal and adjusts it to an appropriate amplitude. The electrical signal (received main signal 13) converted and adjusted by the receiving circuit unit 54 is output to the MAC unit 6 via the card edge connector 51.

The logic control unit 55 outputs the power save control signal 14 output from the MAC unit 6 via the card edge connector 51 to a predetermined circuit block of the optical transceiver 5. The logic control unit 55 performs a logical operation based on the digital control signal 15 output from the MAC unit 6 via the card edge connector 51, and outputs the power save control signal 14 to each output destination (each circuit block). Controls ON / OFF. For example, a device such as a microcontroller is used as the logic control unit 55.

Next, the power save control signal 14 used when the MAC unit 6 performs power save will be described.
The power save control signal 14 is input from the MAC unit 6 to the logic control unit 55 via the card edge connector 51, and is output as a plurality of output signals for each power save mode (= circuit block) to be executed. Here, as shown in FIG. 3, the output signals are divided into a Tx power save control signal 141, a laser shutdown control signal 142, and an Rx power save control signal 143. Although three types of control signals 141 to 143 are shown in FIG. 3, control signals for turning off the power and functions of other circuit blocks may be provided. Which of these control signals is output and the combination of the output signals are based on a power save mode preset by the digital control signal 15.

The Tx power save control signal 141 is a control signal for turning off the entire power of the transmission circuit unit 52 via a device such as the switch 523, for example.
The laser shutdown control signal 142 is a control signal for shutting down only the laser driving unit 522 in the transmission circuit unit 52. Since the laser driving unit 522 is a part of the transmission circuit unit 52, it can respond faster than Tx power saving.
The Rx power save control signal 143 is a control signal for turning off the power of the entire receiving circuit unit 54 via a device such as the switch 541, for example.

The power save control signals 141 to 143 for controlling these power save modes can be turned on / off or logically inverted by the digital control signal 15 input to the logic control unit 55.
That is, the MAC unit 6 selects the most effective power save mode (power save mode with a large response time and low power consumption effect) based on the communication schedule by the OLT 1, and the corresponding output destination (optical transceiver) 5 is generated and is output to the logic control unit 55 together with the power save control signal 14 or before the power save control signal 14 (control signal output step). Then, the logic control unit 55 sets an output destination, that is, a power save mode based on the digital control signal 15 from the MAC unit 6, and outputs the power save control signal 14 to the output destination (output destination selection step).
As a result, it is possible to dynamically transition to a plurality of power save modes (Tx power save, Rx power save, laser shutdown, or a combination thereof) only by assigning one power save control signal 14.

Note that when performing relatively high-speed power saving for controlling the laser driving unit 522, power saving may be performed for each data transmission using the burst control signal 12.
Further, as shown in FIG. 4, in conjunction with the power saving of the receiving circuit unit 54, the power for the TIA (Transimpedance Amplifier) in the light receiving element 533 is saved using the switch 534 and the Rx power saving control signal 143b. You may do it.

Next, the relationship between the traffic volume and the power saving effect in the ONU 2 configured as described above will be described with reference to FIG. FIG. 5A is a graph showing changes in traffic, and FIG. 5B is a graph showing changes in power consumption at that time.
As shown in section A of FIG. 5A, when the communication request is low and the traffic is low, the MAC unit 6 performs the Tx power save and the Rx power save (Tx + Rx power save) with the largest low power consumption effect and the long response time. Apply.

On the other hand, when the traffic increases moderately as in the section B of FIG. 5A, the MAC unit 6 uses the digital control signal 15 at the timing of the code D (the timing before communication in the section B). The logic control unit 55 is switched to Tx power saving. Thereby, although the power saving effect (low power consumption effect) is reduced, the response time is shorter than the Tx + Rx power saving, so that the power saving is possible.

On the other hand, when the traffic becomes higher than the code B as in the section C of FIG. 5A, the MAC unit 6 performs the digital control signal at the timing of the code E (timing before communication in the section C). 15 switches the logic control unit 55 to laser shutdown. As a result, the power saving effect (lower power consumption) is further reduced, but since the response time is shorter than the Tx power saving, the power saving can be performed.
Since the relationship between the response time and the power save mode is an example, the circuit block and function to be turned off can be freely changed depending on the balance between the response time and the low power consumption effect.

Here, an example of power save mode switching control by the PON system is shown. FIG. 6 is a sequence diagram in the case of switching the power save mode led by the OLT 1. In the initial state, the ONU 2 is assumed to have a power save mode of Tx power save mode (Tx Sleep) and a non-power save state (not a power save state).

In the power save mode switching control (OLT1 led) by the PON system, as shown in FIG. 6, first, when the OLT1 transmits a GATE signal to the ONU2, the ONU2 receives the data buffer storage amount (buffer storage) of its own station. Not only the amount but also information such as frame number monitoring and link state change may be notified to OLT 1 to request the first uplink data transmission (steps ST601 and 602).

Next, the OLT 1 determines the buffer accumulation amount based on a threshold value stored in the OLT 1. If the buffer storage amount is “Large”, power saving is not performed. If the buffer storage amount is “Medium”, communication is permitted in the Tx power save mode (Tx Sleep). Is “small” and only when there is no downlink transmission data to the target ONU 2 in the OLT 1, a request to switch to the Tx + Rx power save mode (Tx + Rx Sleep) is made to the target ONU 2 (step ST603). In the following, an example will be described in which the OLT 1 requests the ONU 2 to switch to the Tx + Rx power save mode (Tx + Rx Sleep).

Next, the ONU 2 that has received the switching request from the OLT 1 uses the MAC digital control signal 15 to switch the power saving mode from the Tx power saving mode to the Tx + Rx power saving mode. Then, the first uplink data transmission (switch notification) is performed (step ST604). At this time, the ONU 2 is not yet in the power saving state.

Next, when the OLT 1 receives data (switch notification) from the ONU 2, it registers the power save mode. When the OLT 1 sends the GATE signal again, the ONU 2 buffer accumulation amount notified after the switching notification from the ONU 2 is continuously below the threshold (accumulation amount “small”), and there is downlink transmission data to the target ONU 2 If not, OLT 1 permits communication in the power save state of the power save mode (Tx + Rx power save mode) switched to ONU 2 (steps ST605 to 607).

Next, ONU 2 transmits data to OLT 1 in the power saving state (step ST608). At this time, ONU2 also sleeps on the Rx side (reception circuit unit 54 side), so that the link with OLT1 (Link) does not break, so even if there is no transmission data, Wake up periodically and exist in OLT1. Is notified (step ST609). If the OLT 1 determines that the buffer accumulation amount notified after the switching notification from the ONU 2 is “medium”, it makes a request for switching to the Tx power save mode to the target ONU 2, and the ONU 2 performs the first uplink data. The above sequence is repeated from communication (switch notification) (step ST604).

Next, FIG. 7 shows an example of a sequence for switching the power save mode led by ONU2. The difference from the OLT1 initiative sequence is that the threshold determination is performed in the ONU2.

In the power save mode switching control (ONU2 initiative) by the PON system, as shown in FIG. 7, first, the ONU2 determines the stored data buffer storage amount in the ONU2 with respect to the GATE signal transmitted by the OLT1. Then, the power save mode is determined in the same manner as described above. In the following description, the buffer accumulation amount is “small” and the ONU 2 determines the power saving mode of the local station as Tx + Rx power saving mode (Tx + Rx Sleep). Then, a request for permission to change the power save mode is sent to the OLT 1 (steps ST701 and 702). At this time, the ONU 2 has not yet changed the power save mode.

Next, the OLT 1 that has received the notification confirms whether there is downlink transmission data to the target ONU 2, and if there is no data, permits the change of the power save mode (step ST703). If permitted, as in the above case, first, the power save mode is switched in the first communication, and uplink data transmission (switch notification) is performed to the OLT 1 (step ST704).

Next, the ONU 2 makes a determination again when the next GATE signal is received. If the buffer accumulation amount is “small”, the ONU 2 communicates with the OLT 1 in the power saving state of the switched power saving mode (Tx power saving + Rx power saving mode). (Steps ST705 to 708). At this time, the ONU 2 also sleeps on the Rx side, so that the link with the OLT 1 is not broken, so that a wake is periodically made even if there is no transmission data, and the existence is notified to the OLT 1 (step ST 709). . If the buffer accumulation amount is “medium” at the time of determination again, the ONU 2 notifies the OLT 1 of permission to change to the Tx power save mode (step ST702), and performs the same mode switching control.

As described above, according to the first embodiment, at least one of the power saving control signal 14 that causes the output destination to perform power saving and the circuit block in the optical transceiver 5 is designated as the output destination. The MAC unit 6 that outputs the digital control signal 15 to be output and the logic control unit 55 that outputs the power save control signal 14 from the MAC unit 6 to the output destination specified by the digital control signal 15 are provided. Since the power save mode can be dynamically switched using an existing digital control line, a plurality of power save modes can be realized by one power save control signal 14, and power consumption can be reduced.
Further, the MAC unit 6 generates the digital control signal 15 based on the communication schedule set by the OLT 1, outputs the digital control signal 15 before communication with the OLT 1, and outputs the output destination to the logic control unit 55. Since it is configured to perform the setting, it is possible to dynamically switch to the optimum power save mode before communication with the OLT 1, and it is possible to reduce the power consumption more efficiently.

Embodiment 2. FIG.
In the first embodiment, as shown in FIG. 3, the transmission circuit unit 52, the reception circuit unit 54, and the logic control unit 55 are configured independently. On the other hand, a device in which the transmission circuit unit 52, the reception circuit unit 54, and the logic control unit 55 are integrated may be used, which will be described in detail below with reference to the drawings.
FIG. 8 is a diagram showing a circuit configuration of the optical transceiver 5 according to Embodiment 2 of the present invention. The optical transceiver 5 according to the second embodiment shown in FIG. 8 includes a transmission circuit unit 52, a reception circuit unit 54, and a logic control unit 55 of the optical transceiver 5 according to the first embodiment shown in FIG. The integrated device 56 is replaced. Other configurations are the same, and the same reference numerals are given and description thereof is omitted.

The transmission / reception integrated device 56 has a power save function in advance in addition to the functions of the transmission circuit unit 52, the reception circuit unit 54, and the logic control unit 55. Therefore, as shown in FIG. 3, it is not necessary to configure discrete devices such as the

switches

523 and 541 between the power source and the device, and the function can be stopped inside the device.
The transmission / reception integrated device 56 includes a power save mode table 561 that can dynamically change the power save mode by a digital control signal 15 b output from the MAC unit 6 via the card edge connector 51. . Then, a power save mode is set according to the digital control signal 15b, and the power save is performed by the power save control signal 14b output from the MAC unit 6 via the card edge connector 51. An example of power save mode setting control is the same as in the first embodiment.

As described above, according to the second embodiment, the transmission circuit unit 52, the reception circuit unit 54, and the logic control unit 55 are integrally configured so as to use the power save mode implemented in the device. As compared with the first embodiment, high-speed power save control can be expected.

Embodiment 3 FIG.
In the first embodiment, as shown in FIG. 3, a configuration is shown in which the logic control unit 55 can freely control Tx power save, Rx power save, laser shutdown, and a combination thereof. On the other hand, when there are only two types of power save modes to be implemented (for example, Tx power save and Tx + Rx power save), the logic control unit 55 may be configured more simply, and will be described in detail below with reference to the drawings.
FIG. 9 is a diagram showing a circuit configuration of the optical transceiver 5 according to Embodiment 3 of the present invention. The optical transceiver 5 according to the third embodiment shown in FIG. 9 is obtained by replacing the logic control unit 55 of the optical transceiver 5 according to the first embodiment shown in FIG. 3 with a switch (output destination selection unit) 57. . Other configurations are the same, and the same reference numerals are given and description thereof is omitted.

The switch 57 is a switch that can be switched ON / OFF according to a digital control signal 15 c output from the MAC unit 6 via the card edge connector 51.
Here, when only the Tx power save is performed by controlling only the switch 523, the digital control signal 15c for setting the switch 57 to the OFF (open) state is output, and the power save is performed by the power save control signal 14c. Let On the other hand, when Tx + Rx power saving is to be performed by controlling the switch 523 and the switch 541, the digital control signal 15c for setting the switch 57 to the ON (short circuit) state is output, and the power saving is performed by the power saving control signal 14c. Let

As described above, according to the third embodiment, when there are two types of power save modes to be implemented, the output destination of the power save control signal 14c is changed according to the digital control signal 15c instead of the logic control unit 55. Since the switchable switch 57 is provided, the hardware configuration can be made simpler and less expensive than the first embodiment.

In the present invention, within the scope of the invention, any combination of the embodiments, any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

Since the ONU according to the present invention can dynamically switch the power save mode using an existing digital control line, a plurality of power save modes can be realized with one control signal, and the power consumption can be reduced. Therefore, it is suitable for use in an ONU having a power saving function (low power consumption function) for a built-in optical transceiver.

1 OLT, 2 ONU, 3 optical fiber, 4 star coupler, 5 optical transceiver, 6 MAC unit (control signal output unit), 11 transmission main signal, 12 burst control signal, 13 reception main signal, 14, 14b, 14c power Save control signal, 15, 15b, 15c, digital control signal, 51 card edge connector, 52 transmission circuit unit, 53 optical module, 54 reception circuit unit, 55 logic control unit (output destination selection unit), 56 transmission / reception integrated device, 57 Switch (output destination selection unit), 141 Tx power save control signal, 142 laser shutdown control signal, 143, 143b Rx power save control signal, 521 LD driver, 522 laser drive unit, 523 switch, 531 WDM filter, 532 light emitting element, 533 light receiving element, 34 switch, 541 switch, 561 power save mode table.

Claims

In the ONU that performs power saving of the built-in optical transceiver,
A power save control signal that causes the output destination to perform the power save, and a control signal output unit that outputs a digital control signal designating at least one of the circuit blocks in the optical transceiver as the output destination;
An ONU comprising: an output destination selection unit that outputs the power save control signal from the control signal output unit to an output destination designated by the digital control signal.
The ONU according to claim 1, wherein the control signal output unit generates and outputs the digital control signal based on a communication schedule set by an opposing OLT.
The control signal output unit, based on the communication schedule, outputs the digital control signal and causes the output destination selection unit to set an output destination before communication with the OLT. 2. ONU according to 2.
The ONU according to claim 1, wherein the circuit block in the optical transceiver and the output destination selection unit are integrally formed.
The ONU according to claim 1, wherein the output destination selection unit is a logic control unit that performs a logical operation based on the digital control signal and sets an output destination of the power save control signal.
The ONU according to claim 1, wherein the output destination selection unit is a switch that switches an output destination of the power save control signal in accordance with the digital control signal.
In the control method by the ONU that performs power saving of the built-in optical transceiver,
The control signal output unit outputs a power save control signal that causes the output destination to execute the power save, and a digital control signal that designates at least one of the circuit blocks in the optical transceiver as the output destination. A control signal output step;
An output destination selection unit comprising: an output destination selection step of outputting the power save control signal from the control signal output unit to an output destination designated by the digital control signal.