KR20170077414A - System and method of reducting optical beating interference noise by using delay line based optical filtering - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a technique for reducing optical beating interference (OBI) occurring in multiple connection uplink transmission in an optical communication system based on intensity modulation / direct detection (IM / DD) An optical beating interference noise reduction system according to an exemplary embodiment of the present invention includes a plurality of optical communication network units sharing an OFDM-based optical network, the size of an optical carrier corresponding to a remaining optical communication network unit excluding a specific optical communication network unit, And a communication controller for performing a multiple access uplink transmission using an optical carrier corresponding to the plurality of optical communication network units.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a system and a method for reducing optical beating interference noise through optical delay based on delay line based optical filtering,

TECHNICAL FIELD The present invention relates to a technique for reducing optical beating interference (OBI) occurring in multiple connection uplink transmission in an optical communication system based on intensity modulation / direct detection (IM / DD) .

In most conventional optical transmission systems, the transmission side modulates an output light wave of a laser with an electrical signal to transmit an intensity-modulated signal, irradiates the optical signal received from the reception side directly to the photodiode, Is referred to as an intensity modulation / direct detection (IM / DD) method.

1 is a view for explaining the occurrence of optical beating interference (OBI) in a multiple access uplink transmission based on an intensity modulation / direct detection scheme.

The system 100 illustrated in FIG. 1 illustrates a multiple access uplink transmission system in an optical subscriber network based on orthogonal frequency division multiplexing (OFDM). The light in the laser is not perfectly monochromatic, but is generated randomly around the reference wavelength. That is, the light sources have line widths. Even though the light sources generated in the two optical network units (ONUs) sharing the same central wavelength use different lasers having the same reference wavelength, Phase and frequency. Also, even in the case of source seeding for injecting a light source from an optical line terminal (OLT) using the same laser, the distance between an optical network unit (ONU) Due to the difference, the delay occurs due to the optical path difference. As a result, the light sources modulated by the ONU (optical network unit) are merged and the upstream light sources have different phases. Therefore, at the time of upstream transmission of multiple connections sharing the same central wavelength channel, different light sources transmitted from each optical network unit (ONU) are simultaneously received by an optical line terminal (OLT).

Optical signals transmitted from various optical network units (ONUs) are detected by photo-current detection by square-law detection from a photodetector (PD), and optical carriers The beating noise component of the signal is included.

It appears in the form of a convolution in proportion to the line width of the optical carrier. This OBI makes it impossible to detect an uplink multiple access signal in a system based on orthogonal frequency division multiplexing (OFDM) or subcarrier multiplexing (SCM).

Korean Patent Registration No. 10-0621217 Korean Patent Publication No. 10-0723878

Is to reduce the optical beating interference (OBI) by suppressing the optical carriers of other uplink transmission signals except for one optical carrier.

(OFDMA-PON) or a SCC-PON (SubCarrier Multiplexing-Passive Optical Network) in a system structure of an intensity modulation / direct detection scheme.

The present invention is to provide a technique that utilizes a wide bandwidth in comparison with a method using a wavelength separation technique.

And to provide scalability to WDM by enabling the implementation of colorless optical network units (SONETs) based on source seeding.

Unlike Optical Time Division Multiplex (OTDM), it does not require complicated scheduling, and it reduces system complexity by using a simple passive element compared to a mux.

Unlike polarization division multiplexing (PDM), it provides scalability to the number of optical network units (ONUs).

(OFDMA-PON), which is a potential candidate of a next-generation optical access network, without significantly increasing system complexity by reducing optical beating interference (OBI) will be.

An optical beating interference noise reduction system according to an embodiment is characterized in that a size of an optical carrier corresponding to an optical communication network unit excluding a specific optical communication network unit among a plurality of optical communication network units sharing an OFDM- And a communication controller for performing multiple access uplink transmission using optical carriers corresponding to the plurality of optical communication network units.

The optical carrier processing unit according to an embodiment adjusts a size of an optical carrier corresponding to the remaining optical communication network unit to a value smaller than a threshold value by using an optical interferometer.

The optical carrier processing unit according to an exemplary embodiment may use at least one optical interferometer among a delay line, a ring modulator, and a Mach-Zehnder modulator, Adjust the size of the carrier below the threshold.

The optical carrier processing unit may adjust at least one of a generation period, a depth, and a width of a hole in a light output spectrum so that a size of an optical carrier corresponding to a remaining optical communication network unit excluding the specific optical communication network unit is set to a threshold Or less.

The plurality of optical network units according to an embodiment share the same central wavelength.

The optical carrier corresponding to the specific optical network unit according to an exemplary embodiment is utilized as a reference carrier in a receiving terminal, and the receiving terminal detects the multiple access uplink data using the reference carrier.

According to an embodiment of the present invention, there is provided an optical beating interference noise reduction system including a receiver for receiving an optical carrier adjustment command, and a controller for adjusting a size of an optical carrier through a optical interferometer to a threshold value or less in response to the optical carrier adjustment command , The data modulated by the optical carrier adjusted to be equal to or less than the threshold value is transmitted to the receiving terminal together with the data modulated by the optical carrier equal to or larger than the threshold value and the receiving terminal transmits the modulated data Lt; / RTI >

The controller controls the size of the optical carrier to be less than or equal to a threshold value by using at least one optical interferometer among a delay line, a ring modulator, and a Mach-Zehnder modulator.

A method of operating an optical beating interference noise reduction system according to an exemplary embodiment of the present invention is a method of reducing the size of an optical carrier corresponding to an optical communication network unit excluding a specific optical communication network unit among a plurality of optical communication network units sharing an OFDM- And performing a multiple access uplink transmission using an optical carrier corresponding to the plurality of optical network units.

The step of controlling the threshold value according to an exemplary embodiment may be performed by using at least one optical interferometer among a delay line, a ring modulator, and a Mach-Zehnder modulator, Lt; RTI ID = 0.0 > a < / RTI > threshold value.

According to an exemplary embodiment of the present invention, the step of controlling the threshold value may include adjusting at least one of an occurrence period, a depth, and a width of a hole in a light output spectrum, thereby adjusting the optical carrier corresponding to the remaining optical network unit excluding the specific optical network unit And adjusting the size to a threshold value or less.

The optical carrier corresponding to the specific optical network unit according to an exemplary embodiment is utilized as a reference carrier in a receiving terminal, and the receiving terminal detects the multiple access uplink data using the reference carrier.

According to embodiments, the size of the optical beating interference (OBI) can be reduced by suppressing the optical carrier of another uplink transmission signal except for one optical carrier.

(OFDMA-PON) or a SCC-PON (SubCarrier Multiplexing-Passive Optical Network) in a system structure of an intensity modulation / direct detection scheme.

It provides a technology with high bandwidth utilization efficiency compared with the method using wavelength separation technique.

It provides scalability to WDM by enabling the implementation of colorless ONUs based on source seeding.

Unlike Optical Time Division Multiplex (OTDM), there is no need for complicated scheduling, and system complexity can be reduced by using a simple passive element compared to a mux.

Unlike polarization division multiplexing (PDM), it can provide scalability to the number of optical network units (ONUs).

By reducing optical beating interference (OBI), OFDMA-PON (Orthogonal Frequency Division Multiple Access-Passive Optical Network), which is a potential candidate of next-generation optical network, can be accommodated without significantly increasing system complexity.

1 is a view for explaining the occurrence of optical beating interference (OBI) in a multiple access uplink transmission based on an intensity modulation / direct detection scheme.
2 is a diagram illustrating an optical beating interference noise reduction system according to an embodiment.
3 is a diagram illustrating a specific embodiment of a light beating interference noise reduction system according to an embodiment.
4A is a diagram illustrating a delay line based optical interference simulation setup.
4B is a view for explaining an output according to the delay of FIG. 4A.
4C is a diagram for explaining optical carrier suppression for an uplink transmission signal of OFDMA (Orthogonal Frequency Division Multiple Access) using a delay line.
5 is a diagram illustrating a light beating interference noise reduction system according to another embodiment.
6 is a view for explaining a method of operating the optical beating interference noise reduction system according to an embodiment.

It is to be understood that the specific structural or functional descriptions of embodiments of the present invention disclosed herein are presented for the purpose of describing embodiments only in accordance with the concepts of the present invention, May be embodied in various forms and are not limited to the embodiments described herein.

Embodiments in accordance with the concepts of the present invention are capable of various modifications and may take various forms, so that the embodiments are illustrated in the drawings and described in detail herein. However, it is not intended to limit the embodiments according to the concepts of the present invention to the specific disclosure forms, but includes changes, equivalents, or alternatives falling within the spirit and scope of the present invention.

The terms first, second, or the like may be used to describe various elements, but the elements should not be limited by the terms. The terms may be named for the purpose of distinguishing one element from another, for example without departing from the scope of the right according to the concept of the present invention, the first element being referred to as the second element, Similarly, the second component may also be referred to as the first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Expressions that describe the relationship between components, for example, "between" and "immediately" or "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises ", or" having ", and the like, are used to specify one or more of the features, numbers, steps, operations, elements, But do not preclude the presence or addition of steps, operations, elements, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the patent application is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

2 is a diagram illustrating an optical beating interference noise reduction system 200 according to an embodiment.

According to embodiments, the size of the optical beating interference (OBI) can be reduced by suppressing the optical carrier of another uplink transmission signal except for one optical carrier. Further, by reducing optical beating interference (OBI) without significantly increasing system complexity, it is possible to accommodate OFDMA-PON (Orthogonal Frequency Division Multiple Access-Passive Optical Network), which is a potential candidate of the next generation optical access network have.

To this end, the optical beating interference noise reduction system 200 according to an exemplary embodiment may include an optical carrier processing unit 210 and a communication control unit 220.

First, the optical carrier processing unit 210 adjusts the size of the optical carrier corresponding to the remaining optical communication network units except the specific optical communication network unit among the plurality of optical communication network units sharing the OFDM-based optical network unit to a threshold value or less . For example, the optical carrier processing unit 210 can adjust the size of the optical carrier for the remaining optical communication network units, except for one optical communication network unit among a plurality of optical communication network units sharing the same central wavelength.

The present invention is a technique for reducing the size of a beating component between optical carriers by suppressing the optical carriers of other uplink transmission signals except for one optical carrier, and the optical carriers that are not suppressed can act as reference carriers when performing optical detection at the receiving end . That is, the optical carrier for one optical communication network unit among the plurality of optical communication network units is not adjusted in size, and can be used as a reference when detecting data in the receiving end.

Next, the communication control unit 220 can perform multiple connection uplink transmission using optical carriers corresponding to a plurality of optical communication network units.

That is, the communication control unit 220 combines the data of at least one optical communication network unit whose optical carrier size is not adjusted and the data of the remaining optical communication network unit whose optical carrier size is adjusted to be less than or equal to a threshold value, The modulation scheme can be applied to the receiving end.

The optical carrier processing unit 210 can adjust the size of the optical carrier corresponding to the remaining optical communication network unit to a value smaller than a threshold value by using an optical interferometer. The optical interferometer is a device that divides the light from the same light source into two or more optical paths in an appropriate way and overlaps them to observe the interference fringes. It is used for precise comparison of wavelengths, lengths and distances, comparison of optical distances . For example, the optical carrier processing unit 210 may use at least one optical interferometer, such as a delay line, a ring modulator, and a Mach-Zehnder modulator, to transmit an optical carrier corresponding to the remaining optical communication network units except the specific optical communication network unit Can be adjusted below the threshold value.

In particular, the optical carrier processing unit 210 adjusts at least one of a generation period, a depth, and a width of a hole with respect to a light output spectrum through a delay line to adjust a size of an optical carrier corresponding to a remaining optical communication network unit except for the specific optical communication network unit Can be adjusted below the threshold value.

The ring modulator is a resonator using a ring resonator in which a light having a specific wavelength is resonated in a ring-shaped optical waveguide, and the size of the optical carrier is changed It can be adjusted below the threshold value. The Mach-Zehnder modulator is an interferometer used in various fields such as telecommunication, medical diagnosis, and spectroscopy. It can adjust the optical carrier size below the threshold by using optical path difference of light traveling through two paths. have.

FIG. 3 is a diagram illustrating a specific embodiment of a light beating interference noise reduction system 300 according to an embodiment.

Using the optical beating interference noise mitigation system 300, the effect of optical beating interference in the OFDMA-PON uplink transmission can be mitigated. For reference, the SCM-based system can also reduce the optical beating interference noise with the same operation principle as in FIG.

The optical beating interference noise reduction system 300 can reduce the size of the beating component between the optical carriers by suppressing the optical carriers of the other uplink transmission signals except for one optical carrier.

For example, the optical beating interference noise reduction system 300 may adjust the optical carrier for the optical network unit 320 to a threshold value or less without adjusting the optical carrier for the optical network unit 310. Each of the optical carriers thus generated can be used to modulate data, such as 311 and 321. In the case of an optical carrier adjusted to a size smaller than a threshold value, since the reference gain can not be satisfied, Or can be ignored. On the contrary, in the case of the optical carrier adjusted to a magnitude equal to or greater than the threshold value even if it is not adjusted or adjusted, since the reference gain is satisfied, it can be detected and demodulated by the receiving end 330. For this purpose, at the receiving end 330, it can be utilized as a reference carrier for optical detection at the receiving end 330 for an optical carrier not adjusted to a threshold value or less, i.e., not restrained.

3, the receiver 330 is an optical line terminal (OLT). However, the present invention is not limited to this, and may be interpreted as various entities receiving signals from the optical network units 310 and 320.

4A is a diagram illustrating a delay line based optical interference simulation setup.

As shown in FIG. 4A, the frequency of 193.1 Khz generated from the light source of CW Laser 1 can be divided into two signals through a power splitter. At this time, the separated first signal can be coupled through the X Coupler without any adjustment, and the separated second signal can be coupled via the delay line 401. [ The delay line 401 according to one embodiment can be interpreted as a passive element having a time delay of 3 ns.

4B is a view for explaining an output according to the delay of FIG. 4A.

In order to suppress the optical carrier of the upstream transmission signal in the passive optical network, an effect can be obtained by causing optical interference using a delay line as a passive element.

Reference numeral 410 denotes an output having a band of 0.025 ns, reference numeral 420 denotes an output having a band of 0.05 ns, and reference numeral 430 denotes an output having a band of 0.01 ns. Each output differs in at least one of the generation period, the depth, and the width of the holes, and can be variously used depending on the system characteristics.

By adjusting the delay, the present invention can control the generation period and the depth and width of the spectral hole as a hole, or deep, in the light output spectrum. Such an output optical interference spectrum utilizes optical enhancement / destructive interference, and it is possible to utilize various optical interferometers as well as delay lines.

4C is a diagram for explaining the suppression of the optical carrier 442 for an uplink transmission signal of OFDMA (Orthogonal Frequency Division Multiple Access) using a delay line.

The light output spectrum 441 represents a hole in the frequency band of 192.92Thz. Therefore, the optical carrier 442 at a position corresponding to the hole of the light output spectrum 441 can be suppressed to a size smaller than the threshold value.

In the present invention, it is determined whether or not the optical carrier is adjusted to be equal to or less than a threshold value, whether or not the optical carrier is adjusted to a threshold value or less, or not to be adjusted. In addition, the size adjustment of the optical carrier can be performed by appropriately adjusting the position between the optical output spectrum 441 and the optical carrier 442 in consideration of the determination result.

For example, in the present invention, an optical interference spectrum can be generated, and this spectrum can determine the gain / loss profile of the optical power according to the wavelength (frequency). The optical carrier 442 of the optical signal modulated at the spectral hole position corresponding to the frequency band of 192.92Th experiences a large loss in terms of optical power and the signal has a large gain compared with it.

As a result, the power of the optical carrier is suppressed, and the upstream transmission signal received by the optical line terminal (OLT) only survives the optical carrier transmitted from the optical network unit (ONU). By reducing the size of the upstream optical carriers from the optical network units (ONUs), the beating component between the optical carriers of different upstream transmission signals, that is, optical beating interference (OBI) ) Can be greatly reduced.

As a result, the present invention reduces the influence due to optical beating interference (OBI) to a level similar to that of the entire system noise floor, thereby enabling detection of a signal transmitted upstream from a receiver. The OFDMA-PON (Orthogonal Frequency Division Multiple Access-Passive Optical Network) system within a single wavelength can be implemented.

FIG. 5 is a diagram illustrating a light beating interference noise reduction system 500 according to another embodiment.

In particular, the optical beating interference noise reduction system 500 according to an embodiment may be implemented at the output terminal of each optical network unit (ONU).

The optical beating interference noise reduction system 500 may include a reception unit 510 and a control unit 520.

Receiving unit 510 may receive an optical carrier adjustment command.

The size of the optical carrier for an optical network unit (ONU) other than one optical network unit (ONU) among a plurality of optical network units (ONUs) is adjusted to be less than a threshold value .

To this end, the system may determine whether to adjust the size of the optical carrier for an optical network unit (ONU), and may provide the optical carrier adjustment command to the receiver 510 in accordance with the determination result.

Next, in response to the optical carrier adjustment command, the control unit 520 can adjust the size of the optical carrier through the optical interferometer to a threshold value or less. For example, the control unit 520 may adjust the size of the optical carrier to a threshold or less by using at least one optical interferometer among a delay line, a ring modulator, and a Mach-Zehnder modulator.

As a result, the data modulated by the optical carrier adjusted to the threshold value or less is transmitted to the receiving end together with the data modulated by the optical carrier above the threshold value, and the receiving end demodulates the modulated data based on the optical carrier of the threshold value or more .

6 is a view for explaining a method of operating the optical beating interference noise reduction system according to an embodiment.

The method of operation of the optical beating interference noise reduction system according to an exemplary embodiment adjusts the size of the optical carrier to a threshold value or less (Step 601).

More specifically, an operation method of the optical beating interference noise reduction system is a method of reducing the size of an optical carrier corresponding to a remaining optical network unit except a specific optical network unit among a plurality of optical network units sharing an OFDM- Value. In particular, the operation method of the optical beating interference noise reduction system can reduce the size of the remaining optical carriers excluding one specific optical communication network unit to a threshold value or less. Thereby, only the optical signal from the optical network unit whose optical carrier size is not adjusted can be detected at the receiving end.

In one example, according to the method of operation, at least one optical interferometer may be used, such as a delay line, a ring modulator, or a Mach-Zehnder modulator, to adjust to a threshold value or less. That is, the size of the optical carrier corresponding to the remaining optical communication network units excluding the specific optical communication network unit can be adjusted to a threshold or less by using the optical interferometer.

In particular, according to the operating method of the present invention, at least one of the generation period, the depth, and the width of the hole is adjusted in the optical output spectrum so that the size of the optical carrier corresponding to the remaining optical network unit excluding the specific optical network unit is less than or equal to a threshold value .

Next, an operation method of the optical beating interference noise reduction system according to an embodiment can perform multiple connection uplink transmission by a plurality of optical communication network units using all of the scaled or unadjusted optical carriers 602).

An optical carrier corresponding to a particular optical network unit, i. E., An unscaled optical carrier, can be utilized as a reference carrier at the receiving end. Therefore, the receiving end can detect the data transmitted over the multiple access using the reference carrier.

As a result, by using the present invention, it is possible to reduce optical beating interference (OBI) by suppressing optical carriers of other uplink transmission signals except for one optical carrier.

In addition, it enables uplink transmission in OFDMA-PON (Orthogonal Frequency Division Multiple Access-Passive Optical Network) or SCM-PON (SubCarrier Multiplexing-Passive Optical Network) within the system structure of the intensity modulation / direct detection system, Wavelength separation is a technique that utilizes high bandwidth efficiency. In addition, it enables the implementation of a colorless optical network unit (SONET) based on source seeding to provide scalability to WDM, and unlike Optical Time Division Multiplex (OTDM) No scheduling is required and system complexity can be reduced by using simple passive elements compared to muxes.

On the other hand, according to the present invention, unlike the polarization division multiplexing (PDM), the number of optical network units (ONU) can be extended and the optical beating interference noise (OBI, optical (OFDMA) -PON (Orthogonal Frequency Division Multiple Access-Passive Optical Network), which is a potential candidate of the next generation optical access network, without significantly increasing system complexity.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA) , A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (12)

An optical carrier processing unit for adjusting a size of an optical carrier corresponding to the remaining optical communication network units except a specific optical communication network unit from a plurality of optical communication network units sharing an OFDM-based optical network under a threshold value; And
A communication controller for performing multiple access uplink transmission using optical carriers corresponding to the plurality of optical communication network units;
/ RTI > A system for reducing optical beating interference noise comprising: The method according to claim 1,
The optical carrier processing unit includes:
And adjusting the size of the optical carrier corresponding to the remaining optical communication network unit to be less than or equal to a threshold value by using an optical interferometer. 3. The method of claim 2,
The optical carrier processing unit includes:
A light modulator that adjusts a size of an optical carrier corresponding to a remaining optical network unit excluding the specific optical network unit to a value smaller than a threshold value using at least one optical interferometer among a delay line, a ring modulator, and a Mach-Zehnder modulator, Beading interference noise reduction system. The method according to claim 1,
The optical carrier processing unit includes:
Adjusting a size of an optical carrier corresponding to a remaining optical network unit excluding the specific optical network unit to a value less than a threshold by adjusting at least one of a generation period, a depth, and a width of a hole in the optical output spectrum. The method according to claim 1,
Wherein the plurality of optical network units share the same central wavelength. The method according to claim 1,
Wherein the optical carrier corresponding to the specific optical communication network unit is utilized as a reference carrier in a receiving end and the receiving end detects the multiple access uplink data using the reference carrier. A receiver for receiving an optical carrier adjustment command;
In response to the optical carrier adjustment command, controls the magnitude of the optical carrier through the optical interferometer to be less than or equal to a threshold value,
Lt; / RTI >
The data modulated by the optical carrier adjusted to be equal to or less than the threshold value is transmitted to the receiving end together with the data modulated by the optical carrier equal to or more than the threshold value and the receiving end transmits the modulated data Demodulating optical beating interference noise reduction system. 8. The method of claim 7,
Wherein,
Wherein the size of the optical carrier is adjusted to be less than or equal to a threshold value by using at least one optical interferometer among a delay line, a ring modulator, and a Mach-Zehnder modulator. A method of operating an optical beating interference noise reduction system,
Adjusting a size of an optical carrier corresponding to an optical communication network unit other than a specific optical communication network unit among a plurality of optical network units sharing an OFDM-based optical network unit to a threshold value or less; And
Performing a multiple access uplink transmission using an optical carrier corresponding to the plurality of optical network units
/ RTI > A method of operating a light beating interference noise mitigation system. 10. The method of claim 9,
The step of adjusting to a value below the threshold value,
Adjusting a size of an optical carrier corresponding to a remaining optical network unit excluding the specific optical network unit by using at least one optical interferometer among a delay line, a ring modulator, and a Mach-Zehnder modulator,
/ RTI > A method of operating a light beating interference noise mitigation system. 10. The method of claim 9,
The step of adjusting to a value below the threshold value,
Adjusting at least one of a generation period, a depth, and a width of a hole in a light output spectrum to adjust a size of an optical carrier corresponding to a remaining optical network unit excluding the specific optical network unit to be less than a threshold value
/ RTI > A method of operating a light beating interference noise mitigation system. 10. The method of claim 9,
Wherein the optical carrier corresponding to the specific optical communication network unit is utilized as a reference carrier in a receiving end and the receiving end detects the multiple access uplink data using the reference carrier.

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