KR101860208B1 - Method and apparatus for controlling optical noise in optical communication system - Google Patents

Abstract

The present invention discloses a method and apparatus for suppressing optical noise in an optical communication system. A subscriber terminal for controlling optical noise in an optical communication system according to an embodiment of the present invention includes a receiver for receiving a first light source from an optical line terminal; A first coupler for separating the first light source into a second light source and a third light source, delivering the second light source to an amplifier, and delivering the third light source to a phase modulator; And a second light source that receives the third light source from the second light source and the phase modulator from the amplifier and that combines the second light source and the third light source to generate a fourth light source from which the first light noise is removed, Lt; / RTI > In addition, since the apparatus for suppressing noise in the optical communication system does not require a separate modulator / demodulator, it can be constructed with a simple low-cost structure and is not restricted by the modulation format upon signal modulation, There is an effect applicable to a network using various signal formats because it does not cause a waste of bandwidth or loss of signal band for coding.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for suppressing optical noise in an optical communication system,

The present invention relates to a method and apparatus for suppressing optical noise in an optical communication system.

Generally, in a passive optical network (PON) system, a laser diode (LD) has been used for each subscriber terminal in uplink communication.

However, when constructing a subscriber terminal using a laser diode, there is a disadvantage that the price burden increases in constructing a passive optical network.

In addition, when a subscriber terminal is constructed using a laser diode, wavelength division multiplexing (WDM) using different upstream wavelengths is required for each subscriber terminal, and a process of setting a wavelength separately for each subscriber terminal is required, There is a disadvantage that it is difficult to construct.

Accordingly, in a passive optical network system, a method of using a reflective semiconductor optical amplifier (RSOA) instead of a high-cost laser diode for each optical network unit (ONU) has been proposed in uplink communication.

When a passive optical network structure is constructed using a reflection type semiconductor amplifier, a subscriber terminal can be constructed at a low cost, a colorless subscriber terminal can be constructed, and a power margin can be secured even in long- And the signal can be directly modulated by the reflection type semiconductor amplifier, so that there is an advantage that simple modulation can be performed.

However, when a passive optical network structure is constructed using a reflection type semiconductor amplifier, scattering components in the direction opposite to the traveling direction of the light source due to the nonuniformity of the internal density of the optical fiber when passing through the optical fiber depend on the characteristics of the light source There are disadvantages that can exist.

Generally, the scattering component existing in the opposite direction is called Rayleigh Back Scattering Noise (RBS).

Rayleigh scattering noise is the noise that must occur when light passes through the fiber.

In the passive optical network using the reflection type semiconductor amplifier, the light transmitted / received between the optical line terminal and the subscriber terminal is reflected by the Rayleigh back scattering noise of the light source itself and the Rayleigh back scattering noise of the upstream signal directly modulated by the reflection type semiconductor amplifier .

The Rayleigh backscattering noise of the light source itself and the Rayleigh backscattering noise of the upstream signal directly modulated by the reflection type semiconductor amplifier are as follows. The larger the light source line width, the larger the light source input to the optical fiber, the longer the optical fiber length, Can be increased.

Therefore, the passive optical network system using the reflection type semiconductor amplifier includes the problem that the loss of the upstream signal is caused by the Rayleigh backscattering noise and the transmission performance is deteriorated due to the loss of the upstream signal.

Therefore, there is a demand for a technique for suppressing Rayleigh backscattering noise in a passive optical network using a reflection type semiconductor amplifier.

Korean Patent No. 10-1168761 "A method for generating a phase modulated signal, an apparatus for generating a phase modulated signal, and an optical network using the same, Korean Patent No. 10-1106789 "An apparatus and method for suppressing noise using a light source having a gain saturation effect, and an optical subscriber network having the same" Korean Patent No. 10-1448383 entitled "Optical communication system suppressing RB noise using RF tone"

Jae-Min Lee; Dae-Won Lee; Yong-Yuk Won; Soo-Jin Park; Sang-Kook Han, Reduction of Rayleigh Back-Scattering Noise Using RF Tone in RSOA Based Bidirectional Optical Link, Optical Fiber Communication / National Fiber Optic Engineers Conference, 2008.

SUMMARY OF THE INVENTION The present invention seeks to provide a method and apparatus for suppressing optical noise in an optical communication system.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for removing optical noise in a carrier wave by combining a light source directly modulated in an amplifier and having uplink data and a light source having a phase inversion of 180 degrees in a phase modulator.

The present invention is a method for detecting a light source using a first photodetector, detecting a light source using a second photodetector, subtracting a light source detected using the second photodetector from a light source detected using the first photodetector, A method and an apparatus for removing optical noise of an uplink signal.

A subscriber terminal for controlling optical noise in an optical communication system according to an embodiment of the present invention includes a receiver for receiving a first light source from an optical line terminal; A first coupler for separating the first light source into a second light source and a third light source, delivering the second light source to an amplifier, and delivering the third light source to a phase modulator; And a second light source that receives the third light source from the second light source and the phase modulator from the amplifier and that combines the second light source and the third light source to generate a fourth light source from which the first light noise is removed, Lt; / RTI >

An optical line terminal for controlling optical noise in an optical communication system according to an embodiment of the present invention includes a receiver for receiving a fourth light source from a subscriber terminal; A fifth light source that receives the fifth light source passed through the fourth light source and a power splitter, and a sixth light source that combines the fifth light source and a sixth light source including the uplink data and the second light noise, 1 photodetector; A second photodetector for detecting an eighth light source obtained by subtracting the sixth light source from the fifth light source after receiving the sixth light source among the fourth light sources; And a calculator for subtracting the eighth light source from the seventh light source to remove the second optical noise.

A method for controlling a first optical noise in an optical communication system according to an embodiment of the present invention includes: a step of receiving a first light source from an optical line terminal; Separating the first light source into a second light source and a third light source; Transmitting the second light source to an amplifier; Transmitting the third light source to a phase modulator; Receiving the second light source from the amplifier; Receiving the third light source from the phase modulator; And generating a fourth light source from which the first optical noise is removed by combining the second light source and the third light source.

A method for controlling a second optical noise in an optical communication system according to an embodiment of the present invention includes: a step of receiving a fourth light source from a subscriber terminal; Detecting a seventh light source that is a sum of the fifth light source and a sixth light source including uplink data and second light noise after receiving the fifth light source passing through the fourth light source and the power splitter; Detecting an eighth light source in which the sixth light source is subtracted from the fifth light source after receiving the sixth light source among the fourth light sources; And removing the second optical noise by subtracting the eighth light source from the seventh light source.

Since the apparatus for suppressing noise in the optical communication system according to an embodiment of the present invention does not require a separate modulator / demodulator, it can be constructed with a simple low-cost structure, It does not cause a waste of bandwidth or a loss of signal band for coding, and thus is applicable to a network using various signal formats.

In addition, since the apparatus for suppressing noise in the optical communication system according to the embodiment of the present invention does not change the line width of the light source or the like, it does not have a complicated structure which is sensitive to temperature, vibration, It is possible to increase the design efficiency of the semiconductor device.

In addition, an apparatus for suppressing noise in an optical communication system according to an embodiment of the present invention is capable of removing optical noise that may occur in a structure in which two or more light sources are received by a single receiver.

1 shows a block diagram of a subscriber terminal according to an embodiment of the present invention.
2 shows a block diagram of an optical line terminal according to an embodiment of the present invention.
3 shows a block diagram of an optical communication system according to an embodiment of the present invention.
4 shows another block diagram of a subscriber terminal according to an embodiment of the present invention.
5 illustrates an operation procedure of a subscriber terminal according to an embodiment of the present invention.
6 shows another block diagram of an optical line terminal according to an embodiment of the present invention.
7 illustrates an operational procedure of an optical line terminal according to an embodiment of the present invention.

Hereinafter, various embodiments of the present document will be described with reference to the accompanying drawings.

It is to be understood that the embodiments and terminologies used herein are not intended to limit the invention to the particular embodiments described, but to include various modifications, equivalents, and / or alternatives of the embodiments.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The following terms are defined in consideration of functions in various embodiments and may vary depending on the intention of a user, an operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

In connection with the description of the drawings, like reference numerals may be used for similar components.

The singular expressions may include plural expressions unless the context clearly dictates otherwise.

In this document, the expressions "A or B" or "at least one of A and / or B" and the like may include all possible combinations of the items listed together.

Expressions such as " first, "" second," " first, "or" second, " But is not limited to those components.

When it is mentioned that some (e.g., first) component is "(functionally or communicatively) connected" or "connected" to another (second) component, May be connected directly to the component, or may be connected through another component (e.g., a third component).

As used herein, the term "configured to" is intended to encompass all types of information, including, but not limited to, " , "" Made to "," can do ", or" designed to ".

In some situations, the expression "a device configured to" may mean that the device can "do " with other devices or components.

For example, a processor configured (or configured) to perform the phrases "A, B, and C" may be implemented by executing one or more software programs stored in a memory device or a dedicated processor (e.g., an embedded processor) , And a general purpose processor (e.g., a CPU or an application processor) capable of performing the corresponding operations.

Also, the term 'or' implies an inclusive or 'inclusive' rather than an exclusive or 'exclusive'.

That is, unless expressly stated otherwise or clear from the context, the expression 'x uses a or b' means any of the natural inclusive permutations.

1 shows a block diagram of a subscriber terminal according to an embodiment of the present invention.

In particular, FIG. 1 illustrates components of the subscriber terminal 100.

Hereinafter, terms such as "part," "group," and the like are used to denote units for processing at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

1, a subscriber terminal 100 includes a communication unit 110, a storage unit 120, a coupler 130, an amplifier 140, a phase modulator 150, and a controller 160.

The communication unit 110 performs functions for transmitting and receiving signals through an optical communication channel.

The communication unit 110 performs a function of converting a baseband signal and a bit string according to a physical layer standard of the system.

For example, the communication unit 110 may generate complex symbols by encoding and modulating transmission bit streams during data transmission.

In addition, the communication unit 110 can recover the received bit stream by demodulating and decoding the baseband signal upon receiving the data.

For example, at the time of data transmission, the communication unit 110 can generate demodulation symbols by encoding and modulating a transmission bit stream.

Also, the communication unit 110 up-converts the baseband signal to an RF band signal, transmits the RF band signal through the antenna, and downconverts the RF band signal received through the antenna to a baseband signal.

For example, the communication unit 110 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter (ADC)

In addition, the communication unit 110 may include different communication modules for processing signals of different frequency bands.

For example, different communication standards may include Bluetooth low energy (BLE), Wireless Fidelity (Wi-Fi), WiFig Gigabyte (WiGig), cellular networks (eg Long Term Evolution) have.

Also, different frequency bands may include super high frequency (SHF) (e.g., 2.5 GHz, 5 GHz) and millimeter wave (e.g., 60 GHz) bands.

The communication unit 110 may receive a time slot through a downlink frame to receive uplink communication from the optical line terminal.

For example, the communication unit 110 can be registered in the optical line terminal after receiving the serial number from the optical line terminal, transmitting the serial number requested to the optical line terminal, receiving the identifier from the optical line terminal .

The communication unit 110 includes a transmitter 111 and a receiver 112.

The transmitter 111 can convert an electric signal into an optical signal and transmit the converted optical signal to the optical line terminal.

For example, the optical line terminal may be an optical line terminal (OLT). The optical signal may also be referred to as a light source.

For example, when the transmitter 111 transmits a signal to the optical line terminal, the transmitted signal may be referred to as an upstream signal.

For example, when the transmitter 111 transmits a signal to the optical line terminal, the transmitter 111 is allocated an uplink communication time slot from the optical line terminal and can transmit a signal to the optical line terminal during the allocated time slot .

For example, the signal transmitted by the transmitter 111 may include data. For example, data may be referred to as a source.

The transmitter 111 according to an embodiment of the present invention can transmit the fourth light source from which the first optical noise is removed to the optical line terminal.

For example, the first optical noise refers to Rayleigh Back Scattering (RBS) noise associated with a carrier for transmitting a light source.

For example, the fourth light source refers to a light source that has passed through the first coupler, the second coupler, the phase modulator, and the amplifier at the subscriber terminal 100.

For example, the fourth light source may include data after passing through an amplifier.

The receiver 112 receives the optical signal transmitted from the optical line terminal, converts the received optical signal into an electrical signal, and amplifies the converted electrical signal.

For example, the receiver 112 may include a photodiode that receives the light source, converts the received light source to an electrical signal, and an amplifier that amplifies the converted signal.

A receiver 112 according to an embodiment of the present invention may receive a first light source from an optical line terminal.

For example, the first light source may be an optical signal transmitted from the light source of the optical line terminal.

For example, the first light source may be referred to as a seed.

The storage unit 120 stores data such as a basic program, an application program, and setting information for operating the subscriber terminal 100.

In particular, storage 120 may store at least one set of instructions (e.g., applications) for managing files in accordance with various embodiments.

The storage unit 120 may provide the stored data at the request of the controller 160. [

The storage unit 120 may include volatile and / or non-volatile memory.

The storage unit 120 may store instructions or data related to at least one other component of the subscriber terminal 100. [

The storage unit 120 is included in the subscriber terminal 100 and may be referred to as an 'internal storage' or an 'internal storage'.

The storage unit 120 may store data to be included in the first light source.

The coupler 130 may perform a function of evenly distributing the input power. For example, the coupler 130 may be at least one of a hybrid coupler, a 3 dB coupler, and a branch line coupler.

The coupler 130 may be configured as a multistage coupler in a lattice form in order to increase the bandwidth.

The coupler 130 is used for a path separator and a voltage divider of a balanced amplifier, and can be used as a combiner as it is a complete symmetrical structure.

The coupler 130 may divide the input power by extracting a part of the input power or extracting the input power more than a threshold value.

The coupler 130 includes a first coupler 131 and a second coupler 132.

The first coupler 131 according to an embodiment of the present invention may separate the first light source received from the optical line terminal into the second light source and the third light source.

The first coupler 131 according to an embodiment of the present invention may transmit the second light source of the second light source and the third light source, which are obtained by dividing the first light source, to the amplifier 140.

The first coupler 131 according to an embodiment of the present invention may transmit the third light source to the phase modulator 150.

The second coupler 132 according to an embodiment of the present invention may receive the second light source from the amplifier 140.

For example, the second light source from the amplifier 140 may include uplink data.

The second coupler 132 according to an embodiment of the present invention may receive the third light source from the phase modulator 150.

For example, the third light source from the phase modulator 150 may be a light source whose phase is inverted by 180 degrees.

The second coupler 132 according to an embodiment of the present invention combines the second light source from the amplifier 140 and the third light source from the phase modulator 150 to generate a fourth light source from which the first light noise is removed Can be generated.

The coupler 130 according to an embodiment of the present invention can divide or combine the light source received from the optical line terminal.

The amplifier 140 may include a reflective semiconductor optical amplifier (RSOA).

The reflection type semiconductor amplifier included in the amplifier 140 may support a passive optical network implementation based on a wave division multiplexing scheme.

The subscriber terminal 100 according to an embodiment of the present invention may directly modulate the second light source to include uplink data in the second light source.

For example, the second light source may be transmitted to the amplifier 140 when the subscriber terminal 100 divides the first light source received from the optical line terminal into a first coupler.

The phase modulator 150 may be referred to as an optical phase shifter or an optical phase shifter (OPS).

The phase modulator 150 may change the phase of a light wave (e.g., a light source).

For example, the phase modulator 150 is a device for changing the phase of light. The phase modulator 150 can change the phase of the light source by changing the refractive index through an electric signal applied from the outside of the device.

For example, the electrical signal may be a DC current or a DC voltage.

The phase modulator 150 according to an exemplary embodiment of the present invention can invert the phase of the third light source 180 degrees by using a direct current (DC).

For example, if the phase of the third light source is 90 degrees, the phase modulator 150 may change the phase of the third light source to 270 degrees.

The control unit 160 may control operations performed by the communication unit 110, the storage unit 120, the coupler 130, the amplifier 140, and the phase modulator 150.

The control unit 160 may include a processor, a central processing unit, an application processor, or a communication processor.

For example, the control unit 160 may perform operations and data processing relating to control and / or communication of at least one other component of the subscriber terminal 100.

For example, the control unit 160 may control a plurality of hardware or software components connected to the controller 160 by driving an operating system or an application program, and may perform various data processing and calculations.

For example, the controller 160 may be implemented as a system on chip (SOC). The control unit 160 may load and process commands or data received from at least one of the other components (e.g., non-volatile memory) into the volatile memory and store the resulting data in the non-volatile memory.

For example, the control unit 160 controls the first coupler 131 to divide the first light source into the second light source and the third light source, to transmit the second light source to the amplifier 140, To a modulator (150).

For example, the control unit 160 controls the second coupler 132 to combine the second light source from the amplifier 140 and the third light source from the phase modulator 150 to generate the fourth optical noise- A light source can be generated.

For example, the controller 160 may control the amplifier 140 to directly modulate the second light source to include uplink data in the second light source.

For example, the control unit 160 may apply a direct current to the phase modulator 150 to invert the phase of the third light source by 180 degrees.

For example, the controller 160 controls the communication unit 110 to communicate with the optical line terminal through an optical communication channel.

For example, the control unit 160 may control the subscriber terminal 100 to perform the procedure shown in FIG.

2 shows a block diagram of an optical line terminal according to an embodiment of the present invention.

Specifically, FIG. 2 illustrates the components of the optical line terminal 200.

Hereinafter, terms such as "part," "group," and the like are used to denote units for processing at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

2, the optical line terminal 200 includes a communication unit 210, a storage unit 220, a photodetector 230, and a control unit 240.

For example, the optical line terminal 200 may be a central base station device.

For example, the optical line terminal 200 may be part of an optical network, and may be an optical line terminal of a service provider.

For example, the optical line terminal 200 is a multi-service device for connecting an optical network terminal to another system, and includes a service interface and protocol processing (SIPP) device, a cable television (CATV) Device, a transmitting device, and a network management device.

The communication unit 210 performs a function of converting a baseband signal and a bit string according to a physical layer standard of the system.

For example, the communication unit 210 generates complex symbols by encoding and modulating transmission bit streams during data transmission.

In addition, the communication unit 210 demodulates and decodes the baseband signal upon receiving the data, and restores the received bit stream.

For example, at the time of data transmission, the communication unit 210 generates complex symbols by encoding and modulating transmission bit streams.

Also, upon receiving the data, the communication unit 210 demodulates and decodes the baseband signal to recover the received bit stream.

In addition, the communication unit 210 up-converts the baseband signal to an RF band signal, transmits the RF band signal through the antenna, and downconverts the RF band signal received through the antenna to a baseband signal.

For example, the communication unit 210 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

In addition, the communication unit 210 may include different communication modules for processing signals of different frequency bands.

For example, different communication standards may include Bluetooth low energy, Wi-Fi, WiGig, cellular networks (e.g., LTE, etc.).

Also, different frequency bands may include extreme short wave (e.g., 2.5 GHz, 5 GHz) band, mm wave (e.g., 60 GHz) band.

For example, the communication unit 210 may include a distributor. For example, the distributor may connect the optical line terminal 200 with a plurality of subscriber terminals.

The distributor can distribute a signal transmitted from the optical line terminal 200 to a plurality of subscriber terminals. For example, a splitter refers to a device capable of switching on an optical line basis without optical-to-optical conversion in a fiber-optic network.

The exchange between the large capacity systems is mainly performed, and the circuit exchange can be performed irrespective of the digital frame format of the input signal.

The optical path can be reset by using the bypass transfer function or the network restoration function even when the service is impossible due to the failure between adjacent nodes.

In the following description, the transmission and reception performed through the optical communication channel or the wireless channel are used to mean that the processing as described above is performed by the communication unit 210.

The communication unit 210 may allocate a time slot to each subscriber station using a downlink frame to support uplink communication of a plurality of subscriber stations.

For example, the communication unit 210 can request a serial number from each subscriber terminal and receive the requested serial number.

For example, the serial number may be received in a PLOAM (serial physical layer operations) message.

For example, the DL frame may include a synchronization signal field, a frame counter field, a downlink physical synchronization field including a passive optical network-identity (PON-ID) field for identifying the optical line terminal, and a payload.

The communication unit 210 includes a transmitter 211 and a receiver 212.

The transmitter 211 according to an embodiment of the present invention may transmit a first light source including a second light source that is transmitted to an amplifier of a subscriber terminal and a third light source that is transmitted to a phase modulator of a subscriber terminal to a subscriber terminal.

For example, the second light source and the third light source may include the same amount of power.

For example, the first light source may be divided into a second light source and a third light source by a coupler of a subscriber terminal.

The receiver 212 according to an embodiment of the present invention may receive the fourth light source from which the first optical noise is removed from the subscriber terminal.

For example, the first optical noise may refer to Rayleigh Back Scattering (RBS) noise associated with a carrier for transmitting a light source.

The storage unit 220 stores data such as a basic program, an application program, and setting information for operating the optical line terminal 200.

In particular, storage 220 may store at least one set of instructions (e.g., applications) for managing files in accordance with various embodiments. The storage unit 220 provides the stored data at the request of the controller 260.

The storage unit 220 may include volatile and / or non-volatile memory.

The storage unit 220 may store commands or data related to at least one other component of the optical line terminal 200.

The storage unit 220 stores data such as a basic program, an application program, and setting information for operating the optical line terminal 200.

In particular, storage 220 may store at least one set of instructions (e.g., applications) for managing files in accordance with various embodiments.

At least one instruction set stored in the storage unit 220 may be executed by the control unit 260.

The storage unit 220 provides the stored data at the request of the control unit 260. [

The storage unit 220 is included in the optical line terminal 200 and may be referred to as an 'internal storage' or an 'internal storage'.

The photodetector 230 includes a first photodetector 231 and a second photodetector 232.

The photodetector 230 may convert a light source transmitted from a plurality of subscriber terminals into an electric signal.

For example, the photodetector 230 may be referred to as a photodiode, a photodiode, or the like.

For example, the photodetector 230 may detect data of a fourth light source received from the subscriber terminal.

The first photodetector according to an embodiment of the present invention receives a fifth light source that has passed through a fourth light source and a power splitter, and then outputs a fifth light source, a fifth light source, It is possible to detect the seventh light source that combines the six light sources.

For example, the power splitter may be an optical power splitter or a 3 dB coupler.

The second photodetector according to an embodiment of the present invention may detect an eighth light source obtained by subtracting the sixth light source from the fifth light source after receiving the sixth light source among the fourth light sources.

For example, the photodetector 230 may be referred to as a differential photodetector.

For example, the photodetector 230 can differentially detect the light source received from the subscriber terminal using the first photodetector 231 and the second photodetector 232.

The control unit 240 may control the operations of the communication unit 210, the storage unit 220, and the optical detector 230.

A processor, a central processing unit, an application processor, or a communications processor.

For example, the control unit 260 may perform operations and data processing relating to control and / or communication of at least one other component of the optical line terminal 200. [

For example, the control unit 260 may control a plurality of hardware or software components connected to the control unit 260 by driving an operating system or an application program, and may perform various data processing and calculations.

For example, the control unit 260 may be implemented as a system on chip (SOC). The control unit 260 may load and process the command or data received from at least one of the other components (e.g., non-volatile memory) into the volatile memory and store the resultant data in the nonvolatile memory.

The control unit 260 controls the overall operation of the optical line terminal 200. The control unit 260 may control the overall operations of the communication unit 220 and the storage unit 240.

For example, the control unit 260 transmits and receives optical signals through the communication unit 210. Further, the control unit 260 records and reads data in the storage unit 220. [

To this end, the control unit 260 may include at least one processor or a microprocessor, or may be part of the processor.

In particular, the control unit 260 can control various operations of the optical line terminal 200 that transmits or receives optical signals according to various embodiments described below.

The control unit 260 according to an embodiment of the present invention can receive the light source from the subscriber terminal by controlling the receiver 212. [

The controller 260 controls the first photodetector 231 to receive the fifth light source that has passed through the fourth light source and the power distributor and then outputs the fifth light source and the uplink data and the second And the sixth light source including the optical noise may be combined to detect the seventh light source.

The controller 260 controls the second photodetector 232 to receive the sixth light source among the fourth light sources and then detect the eighth light source that is subtracted from the fifth light source to the sixth light source can do.

The controller 260 according to an embodiment of the present invention may control the calculator 241 to remove the second optical noise by subtracting the eighth light source from the seventh light source.

For example, the operator 241 may be referred to as an electrical subtractor.

For example, the operator 241 may perform an operation of subtracting a specific signal from a specific signal.

For example, the control unit 240 can control the optical line terminal 200 to perform the procedure shown in FIG. 7 and the like below.

3 shows a block diagram of an optical communication system according to an embodiment of the present invention.

3 shows the configurations of the subscriber terminal and the optical line terminal among the components of the optical communication system.

3, the optical line terminal 200 includes a light source supply unit 310, a power distributor 320, a photodetector 230, and a first circulator 330-1.

The subscriber terminal 100 includes a second circulator 330-2, a third circulator 330-3, a first coupler 131, a second coupler 132, and an amplifier 140.

The optical line terminal 200 can transmit the first light source to the subscriber terminal 100 through the light source supply unit 310. [

For example, the first light source is emitted from the light source supply unit 310, input to the first port of the first circulator 330-1 through the power distributor 320, and then output to the second port, (100).

The second circulator 330-2 and the third circulator 330-3 can support the flow of light in the circuit.

For example, when a signal is input to the second circulator 330-2 through the second port of the second circulator 330-2, the signal is output to the third port of the second circulator 330-2 , And when a signal is input to the first port of the second circulator 330-2, the signal can be output to the second port of the second circulator 330-2.

For example, the third circulator 330-3 can transmit a signal in the same manner as the second circulator.

The first coupler 131 may divide the first light source transmitted from the optical line terminal 200 into a second light source and a third light source.

The first coupler 131 transmits the second light source to the amplifier 140 and transmits the third light source to the phase modulator 150.

The amplifier 140 may directly modulate the second light source and include the uplink data in the second light source.

The amplifier 140 may transmit the second light source including the uplink data to the second coupler 132.

The phase modulator 150 may invert the phase of the third light source by 180 degrees. For example, the phase modulator 150 may change the phase of the third light source from 90 degrees to 270 degrees.

For example, the phase modulator 150 inverts the phase of the light source transmitted from the first coupler 180 degrees as an optical phase modulating device.

The phase modulator 150 may transmit a third light source whose phase is inverted 180 degrees to the second coupler 132.

The second coupler 132 according to an embodiment of the present invention combines the second light source transmitted from the amplifier 140 and the third light source transmitted from the phase modulator 150, A light source can be output.

The optical line terminal 200 according to an embodiment of the present invention can receive the fourth light source.

The first circulator 330-1 according to an embodiment of the present invention can transmit the fourth light source to the optical detector 230. [

The photodetector 230 may receive the fourth light source from the first circulator 330-1 and the fifth light source from the power splitter 320. [

The photodetector 230 includes a first photodetector 231 and a second photodetector 232.

The first photodetector 231 according to an embodiment of the present invention receives the fifth light source from the power splitter 320 and outputs the sum of the sixth light source and the fifth light source received by the second photodetector 232 The seventh light source can be detected.

The second photodetector 232 according to an embodiment of the present invention receives the fourth light source from the first circulator 330-1 as the sixth light source and then outputs the fifth light source It is possible to detect an eighth light source which is a result of subtracting the sixth light source from the light source.

The operator according to an embodiment of the present invention can remove the second optical noise by subtracting the eighth light source from the seventh light source.

4 shows another block diagram of a subscriber terminal according to an embodiment of the present invention.

Specifically, FIG. 4 illustrates components of a subscriber terminal according to an embodiment of the present invention in more detail.

Referring to FIG. 4, the subscriber terminal 100 includes two circulators, a first coupler 131, a second coupler 132, and an amplifier 140.

The subscriber terminal 100 receives the first light source from the optical line terminal.

The circulator included in the subscriber terminal 100 supports the flow of the light source on the circuit.

When the subscriber terminal 100 receives the first light source from the optical line terminal, the first light source is transmitted to the first coupler 131 through the circulator.

The first coupler 131 may divide the first light source into the second light source and the third light source.

The first coupler 131 transmits the second light source to the amplifier 140. The circulator transfers the second light source transmitted from the first coupler 131 to the amplifier 140 but does not transmit the second light source to the second coupler.

The first coupler 131 transmits the third light source to the phase modulator 150.

The second light source passing through the first point 401 does not include uplink data.

The phase modulator 150 inverts the phase of the third light source by 180 degrees.

The third light source passing through the third point 405 does not include uplink data and is 180 degrees out of phase with the phase of the second light source 180 degrees.

The amplifier 140 directly modulates the received second light source to include the uplink data in the second light source.

The amplifier 140 transmits the directly modulated second light source to the circulator, and the circulator transfers the second light source to the second coupler 132.

And the second light source passing through the second point 403 includes the uplink data.

The second coupler 132 receives a third light source whose phase is inverted 180 degrees from the phase modulator 150 and receives a second light source including the uplink data from the amplifier 140.

The second coupler 132 couples the second light source from the amplifier 140 and the third light source from the phase modulator 150 so that the first optical noise present in the second light source and the third light source is removed from the fourth And outputs a light source.

The subscriber terminal 100 transmits the fourth light source to the optical line terminal.

The fourth light source passing through the fourth point 407 is removed from the first light noise, and includes the uplink data and the second light noise.

5 illustrates an operation procedure of a subscriber terminal according to an embodiment of the present invention.

Specifically, FIG. 5 illustrates an operation of a subscriber terminal to remove a first optical noise using a first coupler, a second coupler, and a phase modulator.

5, in step 501, the subscriber terminal receives the first light source from the optical line terminal.

For example, the first light source may be a resource for the subscriber terminal to transmit uplink data to the optical line terminal.

In step 503, the subscriber terminal separates the first light source into the second light source and the third light source, transfers the second light source to the amplifier, and transmits the third light source to the phase modulator.

The subscriber terminal can divide the first light source into the second light source and the third light source using the first coupler.

The first coupler may deliver the second light source to the amplifier and the third light source to the phase modulator.

In step 505, the subscriber terminal receives the second light source from the amplifier and receives the third light source from the phase modulator.

The subscriber terminal receives the second light source from the amplifier through the second coupler, and receives the third light source from the phase modulator.

The second light source transmitted from the amplifier may include the uplink data and the optical noise by directly modulating the second light source by the amplifier.

The third light source transmitted from the phase modulator can exhibit a phase difference of 180 degrees with the second light source by inverting the phase of the third light source by 180 degrees.

In step 507, the subscriber terminal can generate the fourth light source from which the first optical noise is removed by combining the second light source and the third light source.

The subscriber terminal may combine the second light source and the third light source using a second coupler.

When the subscriber terminal combines the second light source and the third light source, the subscriber terminal can remove the first optical noise by a phase difference of 180 degrees between the second light source and the third light source.

Also, in the above description, it is described that the subscriber terminal generates the fourth light source, but the second coupler may be configured to output the combined light source after coupling the second light source and the third light source.

6 shows another block diagram of an optical line terminal according to an embodiment of the present invention.

Specifically, FIG. 6 illustrates components of an optical line terminal according to an exemplary embodiment of the present invention in more detail.

6, the optical line terminal 200 includes a light source supply unit 310, a power distributor 320, a circulator, and a photodetector 230.

The optical line terminal 200 transmits the first light source to the subscriber terminal through the light source supply unit 310. [

The optical line terminal 200 receives the fourth light source from which the first optical noise is removed from the subscriber terminal and includes the uplink data.

The optical line terminal 200 transmits the fourth light source received from the subscriber terminal to the photodetector 230 through the circulator.

The photodetector 230 includes a first photodetector 231 and a second photodetector 232.

The first photodetector 231 receives the fifth light source through the power splitter 320.

And the fifth light source may be detected at the first point 601. [

The second photodetector 232 receives the sixth light source including the uplink data and the second optical noise from the circulator.

And the sixth light source may be detected at the second point 603.

The first photodetector 231 detects the seventh light source as a result of summing the fifth light source and the sixth light source.

And the seventh light source may be detected at the third point 605. [

The seventh light source detected by the first photodetector 231 is related to the following equation (1).

[Equation 1]

According to Equation (1), E _LO represents the light source passing through the power splitter 320, E _S represents the uplink data included in the fourth light source through direct modulation in the amplifier, and E _RBS represents the optical noise.

The second photodetector 231 detects the eighth light source as a result of subtracting the sixth light source from the fifth light source.

And the eighth light source can be detected at the fourth point 607. [

The eighth light source detected by the second photodetector 232 is related to the following equation (2).

&Quot; (2) "

According to Equation (2), E _LO represents the light source passing through the power splitter 320, E _S represents the uplink data included in the fourth light source through direct modulation in the amplifier, and E _RBS represents the optical noise.

The optical line terminal 200 subtracts the eighth light source from the seventh light source through the computing unit, thereby removing the second optical noise.

The light source from which the second optical noise is removed through the calculator is related to the following equation (3).

&Quot; (3) "

According to Equation (3), E _LO represents the light source passing through the power splitter 320, E _S represents the uplink data included in the fourth light source through direct modulation in the amplifier, and E _RBS represents the optical noise.

)은 제거되었다. 다만, 파워 분배기(320)에 대한 광 잡음(

)은 존재하나, 상술한 설명에서 제1 광 잡음이 제거된 제4 광원을 수신할 경우, 광 회선 단말(200)은 제1 광 잡음 및 제2 광 잡음이 모두 제거된 상향링크 데이터를 수신할 수 있다.According to Equation (3), the second optical noise

) Were removed. However, the optical noise of the power splitter 320

However, in the above description, when receiving the fourth light source from which the first optical noise is removed, the optical line terminal 200 receives the uplink data from which both the first optical noise and the second optical noise have been removed .

7 illustrates an operational procedure of an optical line terminal according to an embodiment of the present invention.

Specifically, FIG. 7 illustrates an operation procedure for the optical line terminal to remove the second optical noise.

Referring to FIG. 7, in step 701, the optical line terminal receives a fourth light source from the subscriber terminal.

The optical line terminal can receive the fourth light source that includes the uplink data and the first optical noise is removed from the subscriber terminal.

In step 703, the optical line terminal receives the fourth light source and the fifth light source through the photodetector, and then detects the seventh light source, which is the sum of the fifth light source and the sixth light source, through the first photodetector.

For example, the photodetector includes a first photodetector and a second photodetector.

Here, the sixth light source refers to a fourth light source that is detected by the second photodetector.

The seventh light source is related to a value obtained by summing a value corresponding to the fifth light source and a value corresponding to the sixth light source, and then squaring the value.

In step 705, the optical line terminal receives the sixth light source through the second photodetector, and detects an eighth light source obtained by subtracting the sixth light source from the fifth light source.

The eighth light source is related to a value obtained by subtracting a value corresponding to the sixth light source from a value corresponding to the fifth light source and then squaring the value.

For example, the optical line terminal can differentially detect a light source from a subscriber terminal using a first photodetector and a second photodetector in a photodetector.

In step 707, the optical line terminal subtracts the eighth light source from the seventh light source to remove the second optical noise.

The optical line terminal can remove the second optical noise by performing an operation of subtracting a value corresponding to the eighth light source from a value corresponding to the seventh light source by using an arithmetic unit.

For example, the second optical noise may be generated when the subscriber terminal performs direct modulation by an amplifier.

Methods according to the claims or the embodiments described in the specification may be implemented in hardware, software, or a combination of hardware and software.

Such software may be stored on a computer readable storage medium. The computer-readable storage medium includes at least one program (software module), at least one program that when executed by the at least one processor in an electronic device includes instructions that cause the electronic device to perform the method of the present invention .

Such software may be in the form of non-volatile storage such as volatile or read only memory (ROM), or in the form of random access memory (RAM), memory chips, For example, in the form of a memory such as an integrated circuit or in the form of a compact disc-ROM (CD-ROM), a digital versatile disc (DVDs), a magnetic disc, tape, or the like. < / RTI >

The storage and storage media are embodiments of machine-readable storage means suitable for storing programs or programs, including instructions that, when executed, implement the embodiments.

Embodiments provide a program including code for implementing an apparatus or method as claimed in any one of the claims herein, and a machine-readable storage medium storing such a program.

Furthermore, such programs may be electronically delivered by any medium, such as a communication signal carried over a wired or wireless connection, and the embodiments suitably include equivalents.

In the above-described specific embodiments, elements included in the invention have been expressed singular or plural in accordance with the specific embodiments shown.

It should be understood, however, that the singular or plural representations are selected appropriately for the sake of convenience of description and that the above-described embodiments are not limited to the singular or plural constituent elements, , And may be composed of a plurality of elements even if they are represented by a single number.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims, as well as the appended claims.

100:
110:
111: Transmitter
112: receiver
120:
130: Coupler
131: first coupler
132: second coupler
140: amplifier
150: phase modulator
160:
200: optical line terminal
210:
220:
230: Photodetector
231: a first photodetector
232: second photodetector
240:
241: Operator

Claims (15)

A receiver for receiving the first light source from the optical line terminal;
A first coupler for separating the first light source into a second light source and a third light source, delivering the second light source to an amplifier, and delivering the third light source to a phase modulator; And
A second coupler that receives the third light source from the second light source and the phase modulator from the amplifier and generates a fourth light source from which the first light noise is removed by coupling the second light source and the third light source, Lt; / RTI >
The phase modulator inverts the phase of the transmitted third light source by 180 degrees using a DC voltage,
Wherein the inverted third light source does not include uplink data and has a phase difference of 180 degrees with respect to the phase of the second light source
A subscriber terminal for controlling optical noise in an optical communication system.
The method according to claim 1,
Wherein the amplifier directly modulates the second light source to include the uplink data in the second light source
A subscriber terminal for controlling optical noise in an optical communication system.
delete The method according to claim 1,
And a transmitter for transmitting the fourth light source to the optical line terminal
A subscriber terminal for controlling optical noise in an optical communication system.
The method according to claim 1,
The first optical noise is a Rayleigh Back Scattering (RBS) noise associated with a carrier for transmitting a light source
A subscriber terminal for controlling optical noise in an optical communication system.
The method according to claim 1,
The optical line terminal receives a fourth light source from a subscriber terminal, receives a fifth light source that has passed through the fourth light source and a power splitter, and then transmits the fifth light source and the uplink data and the second Detecting a seventh light source including a sixth light source including light noise, detecting an eighth light source obtained by subtracting the sixth light source from the fifth light source after receiving the sixth light source among the fourth light sources, And the eighth light source is subtracted from the seventh light source to remove the second optical noise
A subscriber terminal for controlling optical noise in an optical communication system.
The method according to claim 6,
The fourth light source may be configured such that the first optical noise is removed from the subscriber terminal,
The first optical noise is a Rayleigh Back Scattering (RBS) noise associated with a carrier for transmitting a light source
A subscriber terminal for controlling optical noise in an optical communication system.
The method according to claim 6,
The second optical noise is a Rayleigh backscattering noise associated with the uplink data
A subscriber terminal for controlling optical noise in an optical communication system.
The method according to claim 6,
The optical line terminal transmits a first light source including a second light source that is transmitted to the amplifier of the subscriber terminal and a third light source that is transmitted to the phase modulator of the subscriber terminal to the subscriber terminal
A subscriber terminal for controlling optical noise in an optical communication system.
Receiving a first light source from an optical line terminal;
Separating the first light source into a second light source and a third light source;
Transmitting the second light source to an amplifier;
Transmitting the third light source to a phase modulator;
Receiving the second light source from the amplifier;
Receiving the third light source from the phase modulator; And
And generating a fourth light source from which the first optical noise is removed by combining the second light source and the third light source,
And the third light source is received from the phase modulator,
And inverting the phase of the transmitted third light source by 180 degrees using the DC voltage in the phase modulator,
Wherein the inverted third light source does not include uplink data and has a phase difference of 180 degrees with respect to the phase of the second light source
A method for controlling optical noise in an optical communication system.
11. The method of claim 10,
And directly modulating the second light source to include the uplink data in the second light source
A method for controlling optical noise in an optical communication system.
delete 11. The method of claim 10,
And transmitting the fourth light source to the optical line terminal
A method for controlling optical noise in an optical communication system.
11. The method of claim 10,
The first optical noise may be a Rayleigh Back Scattering (RBS) noise associated with a carrier for transmitting uplink data
A method for controlling optical noise in an optical communication system.
11. The method of claim 10,
Receiving, at the optical line terminal, a fourth light source from a subscriber terminal;
The optical line terminal receives a fifth light source that has passed through the fourth light source and a power splitter, and a sixth light source that includes the fifth light source and a sixth light source including uplink data and second optical noise. 7 a process of detecting a light source;
Detecting, at the optical line terminal, an eighth light source obtained by subtracting the sixth light source from the fifth light source after receiving the sixth light source among the fourth light sources; And
Further comprising the step of, in the optical line terminal, removing the second optical noise by subtracting the eighth light source from the seventh light source
A method for controlling optical noise in an optical communication system.

Images