KR101543984B1 - ONU and Method for trandsmitting and receiving VPN signal in coherent PON system - Google Patents

Abstract

In the present technology, disclosed are an optical network unit (ONU) and a method for transmitting and receiving a VPN signal in a coherent PON system. The disclosed ONU includes: a receiving unit which receives a downward signal from an optical line terminal (OLT) by using a local oscillator; a VPN signal generating unit which generates a first VPN signal by using the local oscillator; and a transmitting unit which transmits the first VPN signal.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical communication network unit and a VPN signal transmitting / receiving method in a coherent PON system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical network unit and a VPN signal transmitting / receiving method, and more particularly, to an optical network unit and a VPN signal transmitting / receiving method in a coherent PON system.

With the growth of smart devices and IoT technology, data traffic is expected to surge further in the future. Most of the increased data traffic is point-to-point traffic due to cloud computing, file sharing, and so on.

In addition, communication data between users in a general PON (Passive Optical Network) system widely used at present is transmitted through communication between an optical network unit (ONU) and an optical line terminal (OLT) do.

1 is a diagram illustrating a structure of a conventional optical network system.

Referring to FIG. 1, a plurality of optical network units 120, 130, and 140 are connected to one optical line terminal 110. A signal transmitted from the optical line terminal 110 to the optical communication network units 120, 130 and 140 is a downlink signal and a signal transmitted from the optical network units 120, 130 and 140 to the optical line terminal 110 is an uplink signal to be.

Such an optical network system can be used as a VPN (Virtual Private Network) system for providing communication services between specific optical network units. Therefore, the VPN signal may be transmitted directly to the optical network unit without having to pass through the optical line terminal 110.

However, in the conventional optical network system, all signals must be transmitted through the optical line terminal 110. Therefore, the VPN signal transmitted from the first optical network unit 120 and the destination is the second optical network unit 130 is also transmitted to the optical line terminal 110 and then to the second optical network unit 130 . That is, the optical line terminal 110 confirms that the destination of the VPN signal transmitted from the first optical network unit 120 is the second optical network unit 130, and transmits the VPN signal to the second optical network unit 130 do.

At this time, the optical line terminal 110 converts the VPN signal of the optical signal type transmitted from the first optical communication network unit 120 into the electric signal, and converts the converted electric signal back to the optical signal form (Optical-Electrical- Optical conversion) to the second optical network unit 130.

When a VPN signal is transmitted / received in an existing optical network system, an optical line terminal must pass through and a signal conversion process is required in the optical line terminal. Therefore, unnecessary bandwidth is wasted and an unnecessary signal conversion process is performed.

In addition, the optical line terminal must perform buffering, scheduling, and routing for processing the VPN signal, so that unnecessary load may occur in the optical line terminal.

It is necessary to study how to transmit and receive VPN signals more efficiently in optical network systems.

The present invention is to provide a method of transmitting and receiving an optical network unit and a VPN signal in a PON system.

In particular, the present invention is to provide a method of transmitting and receiving an optical network unit and a VPN signal in a coherent PON system.

According to an aspect of the present invention, there is provided a coherent PON system including an optical network unit (ONU), the optical line terminal OLT using a first local oscillator, A first optical network unit for receiving a downstream signal from the optical network unit and generating a VPN signal; A second optical network unit for receiving the VPN signal using a second local oscillator; And an upstream signal transmitted from the first and second optical network units is transmitted to the optical line terminal and the VPN signal transmitted from the first optical network unit is transmitted to the second optical network unit, And the second optical network unit provides a coherent PON system for receiving the VPN signal using a homodyne method.

According to another aspect of the present invention, there is provided an optical network unit (ONU) of a coherent PON system, which uses a local oscillator to receive a downlink signal from an optical line terminal (OLT) A receiving unit for receiving the data; A VPN signal generator for generating a first VPN signal using the local oscillator; And a transmitter for transmitting the first VPN signal.

According to another aspect of the present invention, there is provided a method of transmitting a VPN signal in a coherent PON system, the method comprising: receiving a downlink signal from an optical line terminal using a local oscillator; ; Generating a first VPN signal using the local oscillator; And transmitting the VPN signal to an optical communication network unit.

According to another aspect of the present invention, there is provided a method of receiving a VPN signal in a coherent PON system, the method comprising: receiving a downlink signal from an optical line terminal using a local oscillator; ; And receiving the VPN signal transmitted from the optical network unit using the local oscillator, wherein the step of receiving the VPN signal provides a VPN signal receiving method of receiving the VPN signal using a homodyne method .

According to the present invention, the load of the optical line terminal is reduced and the traffic transmitted to the core network can be minimized.

Further, by using a local oscillator for signal reception without employing a separate local oscillator for generating the VPN signal, no additional cost is incurred, and the bandwidth utilization efficiency can be improved by separately using the upstream signal and the VPN signal.

1 is a diagram illustrating a structure of a conventional optical network system.
2 is a view for explaining a coherent PON system according to an embodiment of the present invention.
3 is a view for explaining an optical network unit according to an embodiment of the present invention.
4 is a diagram for explaining a coherent PON system according to a specific embodiment of the present invention.
5 is a diagram for explaining the receiving unit of the optical network unit according to the embodiment of the present invention in more detail.
6 is a diagram for explaining a VPN signal transmission method of a coherent PON system according to an embodiment of the present invention.
7 is a view for explaining a VPN signal receiving method of a coherent PON system according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The present invention proposes a method for transmitting and receiving a VPN (Virtual Private Network) signal in a coherent PON (Passive Optical Network) system and an optical communication network unit for transmitting and receiving a VPN signal.

The present invention generates a VPN signal using a local oscillator for signal reception included in an optical network unit (ONU) of a coherent PON system, and the optical network unit receives a VPN signal using a local oscillator . Generally, the upstream signal is generated through a separate laser diode that exhibits different frequency characteristics from the local oscillator. As a result, the frequency of the VPN signal is different from the frequency of the upstream signal.

The VPN signal can be directly transmitted to the optical network unit without passing through the optical line terminal by filtering or reflecting the signal using different frequency characteristics of the VPN signal and the upstream signal. Accordingly, the load of the optical line terminal (OLT) decreases and the traffic transmitted to the core network can be minimized.

Further, by using a local oscillator for signal reception without employing a separate local oscillator for generating the VPN signal, no additional cost is incurred, and the bandwidth utilization efficiency can be improved by separately using the upstream signal and the VPN signal.

In the following, a case where two optical network units are used will be described as an embodiment, but two or more optical network units may be employed according to the embodiment.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a view for explaining a coherent PON system according to an embodiment of the present invention.

2, the coherent PON system according to an embodiment of the present invention includes a first optical network unit 110, a second optical network unit 120, and a path controller 130.

The optical network unit of the coherent PON system includes a photo diode and a local oscillator for signal reception and a laser diode for signal transmission. The present invention utilizes a local oscillator employed in an optical network unit for VPN signal generation. A laser diode for signal transmission can be used for upstream signal transmission.

The first optical network unit 110 receives the downlink signal from the optical line terminal 140 using the first local oscillator. Then, the first local oscillator is used to generate the VPN signal. The VPN signal is transmitted to the second optical network unit 120. The first local oscillator is used for downlink signal reception and can be used for VPN signal generation at the same time.

The second optical network unit 120 receives the VPN signal using the second local oscillator. At this time, the second optical network unit 120 receives the VPN signal using a homodyne method. As described above, the optical network unit of the coherent PON system includes a local oscillator that generates the same oscillation frequency, so that the second optical network unit 120 can receive the VPN signal using the homodyne method.

The path control unit 130 transmits the uplink signals transmitted from the first and second optical network units 110 and 120 to the optical line terminal 140 and the VPN signal transmitted from the first optical network unit 110 To be transmitted to the second optical network unit (120).

The path controller 130 may pass or reflect a signal according to a frequency characteristic of a signal, and may pass or reflect a signal of a predetermined frequency using a fiber Bragg grating (FBG).

The frequency characteristic of the laser diode for signal transmission differs from the frequency characteristic of the local oscillator. As a result, the frequency of the upstream signal and the frequency of the VPN signal are different from each other. Therefore, the path controller 130 can control the VPN signal to be transmitted to the second optical network unit by passing the upstream signal transmitted to the optical line terminal 140 and reflecting the VPN signal.

As a result, according to the present invention, the load of the optical line terminal 140 decreases and the traffic transmitted to the core network can be minimized. Further, by using a local oscillator for signal reception without employing a separate local oscillator for generating the VPN signal, no additional cost is incurred, and the bandwidth utilization efficiency can be improved by separately using the upstream signal and the VPN signal.

3 is a view for explaining an optical network unit according to an embodiment of the present invention.

3, the optical network unit 300 according to an exemplary embodiment of the present invention includes a receiving unit 310, a VPN signal generating unit 320, and a transmitting unit 330.

The receiving unit 310 receives a downlink signal from the optical line terminal using a local oscillator. The VPN signal generator 320 generates a first VPN signal using a local oscillator. The transmitting unit 330 transmits the first VPN signal.

The receiving unit 310 may receive the second VPN signal using a local oscillator. For example, the first VPN signal may be a VPN signal transmitted by the first optical network unit 110 of FIG. 1 to the second optical network unit 120, and the second VPN signal may be a VPN signal transmitted by the second optical network unit 120 of FIG. May be a VPN signal to be transmitted to the first optical network unit 110.

The second VPN signal may be generated through a local oscillator oscillating at the same frequency as that of the local oscillator of the optical network unit 300 and the receiving unit 310 may receive the second VPN signal using the homodyne method. The optical line terminal generates and transmits a downlink signal using a frequency different from the oscillation frequency of the local oscillator, and the receiver 310 can receive a downlink signal using a heterodyne scheme.

Meanwhile, the optical network unit 300 according to an exemplary embodiment of the present invention may further include an uplink signal generator for generating an uplink signal. The uplink signal generator may include a laser diode, which is different from a laser diode used as a local oscillator, An up signal can be generated using a diode.

4 is a diagram for explaining a coherent PON system according to a specific embodiment of the present invention.

4, the coherent PON system according to the present invention includes a first optical network unit 410, a second optical network unit 420, a path controller 430, and an optical line terminal 440 do.

Since the configuration of the second optical network unit 420 is the same as that of the first optical network unit 410, the first optical network unit 410 will be described in detail below.

More specifically, the first optical network unit 410 includes a receiving unit 411, a local oscillator 413, a modulator 415, a laser diode 417, and an optical circulator 419. The path control unit 430 includes an optical circulator 431, an FBG 433, an optical isolator 435, and a coupler 437. The optical line terminal 440 includes a laser diode 441 and a modulator 443.

The FBG 433 passes the VPN signal and the upstream signal is reflected, and the optical circulator 431 provides the upstream signal and the VPN signal to the FBG 433. The optical isolator 435 for transmitting signals only in one direction receives and outputs the VPN signal passed from the FBG. The coupler 437 couples a plurality of circuits.

Meanwhile, according to the embodiment, the FBG can pass the upstream signal and reflect the VPN signal, and accordingly, the optical circulator, the optical isolator, and the coupler can be configured.

(1) Downward signal

The optical line terminal 440 modulates the downlink signal to the modulator 443 and transmits the downlink signal to the first optical network unit 410. At this time, the downlink signal is transmitted to the frequency f1 of the laser diode 441. The receiving unit 411 of the first optical communication network unit 410 receives the downstream signal having passed through the optical circulator 431 by using the local oscillator 413 and the frequency f1 of the laser diode 441, Since the frequency f2 of the signal 413 is different, the downlink signal is detected using the heterodyne method.

(2) VPN signal

The first optical network unit 410 generates a VPN signal using the local oscillator 413 and the VPN signal modulated by the modulator 415 is transmitted through the optical circulator 431. The VPN signal is transmitted to the optical line terminal 440, but is reflected by the path control unit 430 to the second optical network unit 420.

The optical circulator 431 of the path controller 430 moves the VPN signal transmitted in the direction opposite to the downstream signal to the path where the FBG 433 is located. The FBG 433 passes the VPN signal having the frequency f2 of the local oscillator 413 and the VPN signal is input to the optical isolator 435. [

As a result, the VPN signal is not transmitted to the optical line terminal 440 and can be transmitted to the second optical network unit 420. Since the oscillation frequency of the local oscillator of the second optical network unit 42 is equal to the frequency f2 of the local oscillator 413, the second optical network unit 420 detects the VPN signal using the homodyne method.

(3) Upward signal

The first optical network unit 410 generates an upstream signal and transmits it to the optical line terminal 440 at the frequency f3 of the laser diode 417. [ The upstream signal is provided to the FBG 433 through the optical circulator 431 of the path controller 430. The FBG 433 reflects the upstream signal having the frequency f3 of the laser diode 417 and eventually the upstream signal can be transmitted to the optical line terminal 440. [

5 is a diagram for explaining the receiving unit 411 of the optical network unit according to the embodiment of the present invention in more detail.

5, the receiving unit 411 includes a 90-degree hybrid coupler 510 and a plurality of photodiodes 511 to 514. The 90- The 90-degree hybrid 510 receives a downstream signal and a VPN signal as a reception signal as a coupler and receives an oscillation signal of the local oscillator 413 together.

The photodiodes 511 to 514 detect the downstream signal and the VPN signal using the output signal of the 90 degree hybrid coupler 510. [

6 is a diagram for explaining a VPN signal transmission method of a coherent PON system according to an embodiment of the present invention.

The optical network unit according to the present invention uses a local oscillator to receive a downstream signal from the optical line terminal (S610), and generates a VPN signal using a local oscillator (S620). The optical network unit transmits the generated VPN signal to another optical network unit (S630).

In this case, the optical network unit may receive a downlink signal using a heterodyne scheme, and the local oscillator may be a laser diode. The frequency of the VPN signal corresponds to the oscillation frequency of the local oscillator. Also, the optical communication network unit can generate an uplink signal using a laser diode having a frequency characteristic different from that of a laser diode used as a local oscillator.

7 is a view for explaining a VPN signal receiving method of a coherent PON system according to an embodiment of the present invention.

The optical network unit according to the present invention receives a downstream signal from the optical line terminal using a local oscillator (S710), and receives the VPN signal transmitted from another optical communication network unit using a local oscillator (S720). The frequency of the VPN signal is the same as the frequency of the local oscillator, and thus the optical network unit can receive the VPN signal using the homodyne method.

The above-described technical features may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (13)

In a coherent PON system including optical network units (ONUs)
A first optical network unit for receiving a downstream signal from the optical line terminal (OLT) and generating a VPN signal using the first local oscillator;
A second optical network unit for receiving the VPN signal using a second local oscillator; And
Wherein an upstream signal transmitted from the first and second optical network units is transmitted to the optical line terminal and the VPN signal transmitted from the first optical network unit is transmitted to the second optical network unit And a path control unit
The second optical network unit may be configured to receive the VPN signal using a homodyne scheme
Coherent PON system.
The method according to claim 1,
And the oscillation frequencies of the first local oscillator and the second local oscillator are the same
Coherent PON system.
The method according to claim 1,
The first optical network unit
A method for receiving the downlink signal using a heterodyne scheme
Coherent PON system.
The method according to claim 1,
The path control unit
A fiber Bragg grating (FBG) is used to pass or reflect a signal of a predetermined frequency
Coherent PON system.
The method according to claim 1,
The path control unit
An FBG that passes the VPN signal and reflects the upstream signal;
An optical circulator for providing the uplink signal and the VPN signal to the FBG; And
An optical isolator receiving the VPN signal passed from the FBG,
And a coherent PON system.

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