KR101951996B1 - Apparatus and method for compensating for dispersion property of optical fiber in optical transmission system - Google Patents

Abstract

The present invention discloses an apparatus and method for compensating dispersion characteristics of an optical fiber in an optical transmission system. An optical line terminal according to an embodiment of the present invention includes: a transmission unit for transmitting a first optical signal to a subscriber terminal through an optical fiber; A receiver for receiving a feedback signal related to a reception state of the first optical signal from a subscriber terminal; And a predistortion section for generating a nonlinearly modulated second optical signal based on the feedback signal.

Description

[0001] APPARATUS AND METHOD FOR COMPENSATING FOR OPTICAL TRANSMISSION SYSTEM [0002] BACKGROUND OF THE INVENTION [0003]

The present invention relates to an apparatus and method for compensating dispersion characteristics of an optical fiber in an optical communication system.

Optical communication technology has various advantages over electric communication in which electric signals are exchanged using copper wires.

First, since there is almost no interference by external electromagnetic waves, it is economical to transmit a distance of several tens to several hundred km without a repeater. Second, eavesdropping from outside is impossible. Third, optical fiber is a bundle of optical fibers bundled with cables, which can transmit and receive a large amount of information at the same time.

Therefore, optical communication technology has been widely used for a long distance high capacity transmission system due to advantages of optical fiber such as low loss, broadband, security and the like.

The optical transmission system may be composed of an optical transmitter, an optical fiber, and an optical receiver.

The electric signal at the optical transmitter is modulated into an optical signal and then transmitted to the receiver through the optical fiber.

The optical receiver serves to convert the transmitted optical signal into an electrical signal. However, due to the dispersion characteristics of the optical fiber, the signals modulated at the transmitting end are transmitted at different speeds according to the optical frequency while passing through the optical fiber, and the signal is distorted.

The wider the line width of the used optical carrier, the wider the signal bandwidth, and the longer the transmission distance, the more serious it becomes.

Signal distortion can cause nonlinear components. In the case of a digital signal such as an ASK (Amplitude Shift Keying) signal, since a signal is divided into 0 and 1 even if a nonlinear component occurs, there may be an advantage that the signal is stronger than a nonlinear component in comparison with an analog signal.

However, in order to accommodate the recent surging traffic, analog optical transmission technology such as OFDM (Orthogonal Frequency Division Multiplexing) signal has been mentioned.

In the case of a transmission scheme using a plurality of subcarriers, the nonlinear component of the original signal generated in the optical fiber has a direct influence on a signal having a different frequency, thereby including a problem of degrading transmission characteristics.

The signal processing algorithm for compensating the nonlinearity of the optical fiber has a problem in that the system complexity and cost increase.

Also, when a special optical fiber for compensating chromatic dispersion for compensating the nonlinearity of the optical fiber is used, the system cost increases.

In addition, when the signal frequency is selectively used to avoid the non-linear component of the optical fiber, the bandwidth efficiency is reduced.

Therefore, there is a need for a method for compensating for nonlinear components of the optical fiber without increasing system complexity, cost, and bandwidth efficiency.

Korean Patent Laid-Open No. 10-2015-0070334 entitled " Method and system for compensating chromatic dispersion and nonlinearity in a coherent optical communication system " Korean Patent Application No. 10-2006-0039986 "Spectrum Inversion Apparatus for Compensating for Distortion of Optical Signal and Method Thereof" Korean Patent Publication No. 10-2007-0097787 "Optical signal processing method and apparatus of optical communication system"

Xiang Liu; Effenberger. Frank, ONU-Dependent Dispersion Pre-compensation at OLT for high-speed wide-coverage PON, Global Communications Conference, 2015 IEEE

The present invention provides an apparatus and method for compensating dispersion characteristics of optical fibers in an optical communication system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for receiving a feedback signal related to a reception state of a first optical signal from a subscriber terminal.

SUMMARY OF THE INVENTION The present invention is directed to an apparatus and method for generating a nonlinearly modulated second optical signal based on a feedback signal associated with a reception state of a first optical signal.

The present invention provides an apparatus and method for generating a second optical signal that is nonlinearly modulated based on at least one of a degree of nonlinear modulation of a first optical signal, a distance between an optical line terminal and a subscriber terminal, and a bandwidth of the first optical signal I want to.

An object of the present invention is to provide an apparatus and method for receiving a modulated linear signal according to nonlinear characteristics of an optical fiber after passing through an optical fiber.

An apparatus and method for transmitting a second optical signal, which is nonlinearly modulated based on a feedback signal related to a reception state of a first optical signal, to a subscriber terminal.

An optical line terminal according to an embodiment of the present invention includes: a transmission unit for transmitting a first optical signal to a subscriber terminal through an optical fiber; A receiver for receiving a feedback signal related to a reception state of the first optical signal from a subscriber terminal; And a predistortion section for generating a nonlinearly modulated second optical signal based on the feedback signal.

A subscriber terminal according to an embodiment of the present invention includes a receiver for receiving a first optical signal from an optical line terminal through an optical fiber; And a transmission unit for transmitting a feedback signal related to a reception state of the first optical signal to the optical line terminal, wherein the feedback signal includes information indicating the degree of nonlinear modulation of the nonlinearly modulated first optical signal according to the nonlinear characteristic of the optical fiber.

A method of operating an optical line terminal according to an embodiment of the present invention includes transmitting a first optical signal to an optical line terminal through an optical fiber; Receiving a feedback signal associated with a first optical signal from a subscriber terminal; And generating a nonlinearly modulated second optical signal based on the feedback signal.

A method of operating a subscriber terminal according to an embodiment of the present invention includes receiving a first optical signal from an optical line terminal through an optical fiber; And transmitting a feedback signal associated with the first optical signal to the optical line terminal, wherein the feedback signal includes information indicative of the nonlinearity of the nonlinearly modulated first optical signal according to the nonlinear characteristics of the optical fiber.

In an optical communication system according to an embodiment of the present invention, an optical line terminal transmits a first optical signal to a subscriber terminal through an optical fiber, receives a feedback signal related to a reception state of a first optical signal from a subscriber terminal, Linearly modulated second optical signal and transmitting the second optical signal to the subscriber terminal, thereby compensating for the nonlinear characteristics of the optical fiber, thereby improving transmission performance by suppressing nonlinear components without additional components.

In addition, in the optical communication system according to the embodiment of the present invention, the optical line terminal has the effect of constructing the long-distance optical transmission system without increasing the system cost and reducing the bandwidth efficiency by suppressing nonlinear components without additional components.

1 shows a block diagram of an optical line terminal according to an embodiment of the present invention.
2 shows a block diagram of a subscriber 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.
FIG. 4 illustrates an operation procedure of an optical line 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.
FIG. 6 is a graph of output signals versus input signals in an optical communication system 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 an optical line terminal according to an embodiment of the present invention.

Specifically, FIG. 1 illustrates components of the optical line 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, the optical line terminal 100 includes a communication unit 110, a storage unit 120, a control unit 130, and a predistorter 132.

For example, the optical line terminal 100 may be a central base station device.

For example, the optical line terminal 100 may be a part of an optical network, and may be an optical line terminal of a service provider.

For example, the optical line terminal 100 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 110 performs functions for transmitting and receiving optical signals through the optical fiber.

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), WiGig (WiFi Gigabyte), cellular networks such as Long Term Evolution (LTE) .

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 includes a transmitting unit 112 and a receiving unit 114.

The transmission unit 112 may convert the electrical signal into an optical signal and transmit the optical signal to the subscriber terminal.

The transmitting unit 112 according to an embodiment of the present invention transmits the first optical signal to the subscriber terminal through the optical fiber.

For example, the first optical signal may be used as a test signal, after passing through the optical fiber, to test the nonlinear modulation result of the optical fiber.

The transmitter 112 according to an exemplary embodiment of the present invention may transmit a non-linearly modulated second optical signal to a subscriber terminal.

The receiving unit 114 receives the optical signal from the subscriber terminal through the optical fiber, and can convert the optical signal into an electrical signal.

The receiver 114 according to an embodiment of the present invention may receive a feedback signal related to the reception state of the first optical signal from the subscriber terminal.

For example, the reception state of the first optical signal may indicate a degree of nonlinear modulation according to the nonlinear characteristic of the optical fiber after the first optical signal passes through the optical fiber.

The feedback signal according to an embodiment of the present invention includes information indicating the degree of nonlinear modulation of the nonlinearly modulated first optical signal according to the nonlinear characteristic of the optical fiber.

The storage unit 120 stores data such as a basic program, an application program, and setting information for operating the optical line 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 provides the stored data at the request of the controller 130.

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

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

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

At least one instruction set stored in the storage unit 120 may be executed by the control unit 130. [

The storage unit 120 provides the stored data at the request of the controller 130.

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

The control unit 130 can control the overall operation of the optical line terminal 100.

The control unit 130 may control the operations of the communication unit 110 and the storage unit 120. [

The control unit 130 may include a processor, a central processing unit, an application processor, or a communication processor.

For example, the control unit 130 may perform operations and data processing relating to control and / or communication of at least one other component of the optical line terminal 100. [

For example, the control unit 130 may control a plurality of hardware or software components connected to the control unit 130 by driving an operating system or an application program, and may perform various data processing and calculations.

For example, the control unit 130 may be implemented as a system on chip (SOC). The control unit 130 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 130 may transmit and receive optical signals through the communication unit 110 according to an embodiment of the present invention.

The controller 130 according to an embodiment of the present invention can write and read data to and from the storage unit 120.

To this end, the control unit 130 may include at least one processor or a microprocessor, or may be part of the processor.

In particular, the control unit 130 may control various operations of the optical line terminal 100 that transmits or receives optical signals according to various embodiments described below.

The controller 130 according to an embodiment of the present invention may control the transmitter 112 to transmit the first optical signal to the subscriber terminal through the optical fiber.

The control unit 130 according to an embodiment of the present invention can receive the feedback signal related to the reception state of the first optical signal from the subscriber terminal by controlling the reception unit 114. [

The controller 130 according to an exemplary embodiment of the present invention includes a predistorter 132.

The controller 130 according to an exemplary embodiment of the present invention may generate a nonlinearly modulated second optical signal based on the feedback signal.

The controller 130 according to an embodiment of the present invention can generate the second optical signal by non-linearly modulating the light source based on the feedback signal.

The feedback signal according to an embodiment of the present invention may include information indicating the degree of modulation of the nonlinearly modulated first optical signal according to the nonlinear characteristic of the optical fiber.

The predistortion unit according to an embodiment of the present invention may include a nonlinearly modulated second optical signal based on at least one of the degree of nonlinear modulation of the first optical signal, the distance between the optical line terminal and the subscriber terminal, and the bandwidth of the first optical signal. Lt; / RTI >

The control unit 130 according to an embodiment of the present invention may control the transmission unit 112 to transmit the non-linearly modulated second optical signal to the subscriber terminal.

The second optical signal according to an embodiment of the present invention may be modulated into a linear signal according to nonlinear characteristics of the optical fiber after passing through the optical fiber.

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

In particular, FIG. 2 illustrates the components of the subscriber 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.

Referring to FIG. 2, the subscriber terminal 200 includes a communication unit 210 and a storage unit 220.

The communication unit 210 performs functions for transmitting and receiving signals through an optical communication channel.

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 may generate complex symbols by encoding and modulating a transmission bit stream during data transmission.

Also, the communication unit 210 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 210 can generate demodulation symbols by encoding and modulating a transmission 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), and the like.

Also, different frequency bands may include extreme shortwave and mm wavebands.

The communication unit 210 may receive a time slot through a downlink frame to receive uplink communication from the optical line terminal.

For example, the communication unit 210 may receive the serial number from the optical line terminal, transmit the serial number requested to the optical line terminal, and then receive the identifier from the optical line terminal and then register with the optical line terminal .

The communication unit 210 includes a transmitting unit 212 and a receiving unit 214.

The transmitting unit 212 can convert an electric signal into an optical signal, and transmit the converted optical signal to the optical line terminal.

For example, when the transmitter 212 transmits a signal to the optical line terminal, the transmitted signal may be referred to as an upstream signal.

For example, when the transmitter 212 transmits a signal to the optical line terminal, the transmitter 212 allocates an uplink communication time slot from the optical line terminal and transmits a signal to the optical line terminal during the allocated time slot can do.

The transmitter 212 according to an embodiment of the present invention may transmit a feedback signal related to the reception state of the first optical signal to the optical line terminal.

The feedback signal according to an embodiment of the present invention may include information indicating the degree of nonlinear modulation of the nonlinearly modulated first optical signal according to the nonlinear characteristic according to the nonlinear characteristic of the optical fiber.

The receiving unit 214 according to an embodiment of the present invention can receive the non-linearly modulated second optical signal from the optical line terminal.

The storage unit 220 stores data such as a basic program, an application program, and setting information for operating the subscriber 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 230.

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

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

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

At least one instruction set stored in the storage unit 220 may be executed by the control unit 230. [

The storage unit 220 provides the stored data at the request of the controller 230.

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

The control unit 230 may control operations of the communication unit 210 and the storage unit 220. [

The control unit 230 may include a processor, a central processing unit, an application processor, or a communication processor.

For example, the control unit 230 may perform an operation or data processing related to control and / or communication of at least one other component of the subscriber terminal 200. For example,

For example, the control unit 230 may control a plurality of hardware or software components connected to the control unit 230 by driving an operating system or an application program, and may perform various data processing and calculations.

For example, the controller 230 may be implemented as a system on chip (SOC). The control unit 230 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 230 controls the overall operation of the subscriber terminal 200. The control unit 230 may control overall operations of the communication unit 210 and the storage unit 220. [

For example, the control unit 230 transmits and receives optical signals through the communication unit 210. [ Also, the controller 230 writes data to the storage unit 220 and reads the data.

To this end, the control unit 230 may include at least one processor or a microprocessor, or may be part of a processor.

The control unit 230 according to an embodiment of the present invention can receive the first optical signal from the optical line terminal through the optical fiber by controlling the receiving unit 114. [

The control unit 230 according to an embodiment of the present invention may control the transmission unit 112 to transmit a feedback signal related to the reception state of the first optical signal to the optical line terminal.

The feedback signal according to an embodiment of the present invention may include information indicating the degree of nonlinear modulation of the nonlinearly modulated first optical signal according to the nonlinear characteristic of the optical fiber.

The controller 230 according to an embodiment of the present invention can receive the second optical signal that is nonlinearly modulated from the optical line terminal by controlling the receiver 114. [

The nonlinearly modulated second optical signal according to an embodiment of the present invention is characterized in that the optical signal is modulated based on at least one of the degree of nonlinear modulation of the first optical signal, the distance between the optical line terminal and the subscriber terminal, Can be generated by the terminal.

The nonlinearly modulated second optical signal according to an embodiment of the present invention may be modulated into a linear signal according to nonlinear characteristics of the optical fiber after passing through the optical fiber.

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

3 illustrates an optical communication system in which an optical line terminal transmits and receives an optical signal to and from a subscriber terminal through an optical fiber.

3, the optical line terminal 100 modulates an electric signal into an optical signal and transmits the optical signal to the subscriber terminal 200 through the optical fiber 300. The optical line terminal 100 transmits the optical fiber 300 And receives the optical signal from the subscriber terminal 200 and modulates the optical signal into an electrical signal.

 The subscriber terminal 200 receives an optical signal through the optical fiber 300, and then modulates the optical signal into an electrical signal.

The optical fiber 300 modulates a signal characteristic of an optical signal passing through the optical fiber 300 according to dispersion characteristics of the optical fiber.

For example, when the optical line terminal 100 transmits an optical signal having a linear characteristic through the optical fiber 300, the optical signal having a linear characteristic can be modulated into a nonlinear optical signal.

The optical signal passing through the optical fiber 300 is transmitted at different speeds depending on the optical frequency and can be distorted.

The wider the signal bandwidth, the longer the transmission distance, and the greater the signal distortion, the wider the line width of the optical carrier used to transmit the optical signal.

The signal distortion characteristics of the optical fiber 300 can produce a non-linear component of the optical signal passing through the optical fiber 300.

A subscriber terminal 200 according to an embodiment of the present invention modulates an optical signal having passed through an optical fiber 300 into an electrical signal and then generates a feedback signal related to the electrical signal and outputs the generated feedback signal to the optical line terminal 100).

The optical line terminal 100 according to an embodiment of the present invention can determine the dispersion characteristic of the optical fiber 300 based on the feedback signal.

The optical line terminal 100 according to an embodiment of the present invention can modulate an electric signal into an optical signal in consideration of dispersion characteristics of the optical fiber 300. [

For example, modulating an optical signal before the optical line terminal 100 passes through the optical fiber 300 may be referred to as predistortion modulation.

For example, the signal distortion due to the dispersion characteristics of the optical fiber 300 can be increased based on the transmission distance of the optical signal.

FIG. 4 illustrates an operation procedure of an optical line terminal according to an embodiment of the present invention.

4 is a diagram illustrating an example in which the optical line terminal transmits a first optical signal to a subscriber terminal through an optical fiber and then receives a feedback signal related to a reception state of the first optical signal from the subscriber terminal, Thereby generating a nonlinearly modulated second optical signal.

Referring to FIG. 4, in step 401, the optical line terminal transmits a first optical signal through an optical fiber.

The optical line terminal according to an embodiment of the present invention can transmit the first optical signal to the subscriber terminal through the optical fiber.

For example, the first optical signal may be a testing signal for the optical line terminal to verify the nonlinear modulation characteristics of the optical fiber.

In step 403, the optical line terminal can receive a feedback signal related to the reception state of the first optical signal.

The optical line terminal according to an embodiment of the present invention can receive a feedback signal related to the reception state of the first optical signal from the subscriber terminal.

For example, the reception state of the first optical signal may indicate the degree of nonlinear modulation of the first optical signal transmitted through the optical fiber.

For example, after passing through the optical fiber, the characteristics of the signal indicative of the ratio of the input to the output of the first optical signal can be non-linearly modulated.

According to another embodiment, the optical line terminal can receive a feedback signal from a subscriber terminal according to a wireless communication standard. For example, wireless communication standards may include Bluetooth low energy, Wi-Fi, WiGig, cellular networks (e.g., LTE), and the like.

In step 405, the optical line terminal generates a nonlinearly modulated second optical signal.

The optical line terminal according to an embodiment of the present invention can generate a nonlinearly modulated second optical signal based on a feedback signal.

The optical line terminal according to an embodiment of the present invention performs nonlinear modulation before transmitting a second optical signal based on a feedback signal related to the reception state of the first optical signal at the subscriber terminal, So that an optical signal can be generated.

The optical line terminal according to an exemplary embodiment of the present invention may include a second optical signal that is nonlinearly modulated based on at least one of a nonlinearity of the first optical signal, a distance between the optical line terminal and the subscriber terminal, Lt; / RTI >

In step 407, the optical line terminal transmits the second optical signal through the optical fiber.

The optical line terminal according to an embodiment of the present invention can transmit a nonlinearly modulated second optical signal.

The nonlinearly modulated second optical signal according to an embodiment of the present invention may be modulated into a linear signal according to nonlinear characteristics of the optical fiber after passing through the optical fiber.

For example, after passing through the optical fiber, the second optical signal can be modulated into a linear signal according to nonlinear modulation characteristics of the optical fiber. For example, the nonlinear modulation characteristic of an optical fiber may be a dispersion characteristic of the optical fiber.

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

5 is a block diagram of a subscriber terminal that receives a first optical signal from an optical line terminal through an optical fiber, transmits a feedback signal related to a reception state of the first optical signal to the optical line terminal, 2 < / RTI > optical signal.

Referring to FIG. 5, in step 501, a subscriber terminal receives a first optical signal through an optical fiber.

A subscriber terminal according to an embodiment of the present invention can receive a first optical signal from an optical line terminal through an optical fiber.

For example, the first optical signal may be a testing signal for the optical line terminal to confirm the nonlinear modulation characteristics of the optical fiber.

In step 503, the subscriber terminal transmits a feedback signal related to the reception state of the first optical signal.

A subscriber terminal according to an embodiment of the present invention can transmit a feedback signal related to the reception state of the first optical signal from the optical line terminal.

For example, the reception state of the first optical signal may indicate the degree of nonlinear modulation of the first optical signal transmitted through the optical fiber.

For example, after the first optical signal passes through the optical fiber, the characteristic of the signal indicative of the ratio of the input to the output of the first optical signal may be non-linearly modulated.

According to another embodiment, the optical line terminal can receive a feedback signal from a subscriber terminal according to a wireless communication standard. For example, wireless communication standards may include Bluetooth low energy, Wi-Fi, WiGig, cellular networks (e.g., LTE), and the like.

In step 505, the subscriber terminal receives the second optical signal through the optical fiber.

A subscriber terminal according to an embodiment of the present invention can receive a linearly modulated second optical signal through an optical fiber.

The nonlinearly modulated second optical signal in the optical line terminal according to an embodiment of the present invention may be modulated into a linear signal according to nonlinear characteristics of the optical fiber after passing through the optical fiber.

For example, after passing through the optical fiber, the second optical signal can be modulated into a linear signal according to nonlinear modulation characteristics of the optical fiber.

The optical line terminal according to an embodiment of the present invention can generate a nonlinearly modulated second optical signal based on a feedback signal.

For example, the second optical signal is nonlinearly modulated and nonlinearly modulated by the optical line terminal before transmitting the second optical signal based on the feedback signal related to the reception state of the first optical signal at the subscriber terminal Lt; / RTI >

The nonlinearly modulated second optical signal according to an embodiment of the present invention is characterized in that the optical signal is modulated based on at least one of the degree of nonlinear modulation of the first optical signal, the distance between the optical line terminal and the subscriber terminal, May be generated by the terminal, passed through the optical fiber, and then modulated into a linear signal according to the nonlinear characteristics of the optical fiber.

FIG. 6 is a graph of output signals versus input signals in an optical communication system according to an embodiment of the present invention.

Specifically, FIG. 6 illustrates a graph illustrating a characteristic that an input signal of an optical line terminal is modulated and output nonlinearly after passing through an optical fiber.

Referring to FIG. 6, the abscissa of the graph represents the input (transmission) of the optical signal, and the ordinate of the graph represents the output (reception) of the optical signal.

For example, a graph represents a signal output from an optical fiber in comparison with a signal input to the optical fiber.

For example, the graph may indicate the dispersion characteristics of the optical fiber.

The graph 601 shows the modulation state of the first optical signal after passing through the optical fiber. The first optical signal transmitted by the optical line terminal may be a linear signal.

After the first optical signal passes through the optical fiber, the ratio of the output to the input can be nonlinearly modulated.

The graph 601 may represent nonlinear characteristics of the optical fiber.

Graph 603 represents the modulation state of the second optical signal before passing through the optical fiber. In the graph 603, the second optical signal represents the state of the signal modulated based on the feedback signal associated with the modulation state of the first optical signal before the optical line terminal transmits the optical signal.

The graph 603 represents a ratio of input to output of an optical signal obtained by modulating the optical signal before referring to the linearly modulated first optical signal showing optical modulation characteristics of the optical fiber terminal.

The graph 605 shows a linear signal after passing through the optical fiber, in which the second optical signal is modulated according to the modulation characteristic of the optical fiber.

The graph 605 indicates that the second optical signal generated by referring to the feedback signal related to the nonlinearly modulated first optical signal by the optical line terminal is modulated into a linear signal after passing through the optical fiber.

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: optical line terminal
110:
120:
130:
132: Predistortion portion
200: subscriber terminal
210:
220:
230:

Claims (16)

A transmission unit for transmitting a first optical signal, which is a linear signal for confirming nonlinear modulation characteristics of the optical fiber, to a subscriber terminal through an optical fiber;
A receiver for receiving a feedback signal related to a reception state of the first optical signal from the subscriber terminal; And
And a pre-distortion section for generating a non-linearly modulated second optical signal based on the feedback signal,
Wherein the feedback signal includes information indicating a degree of nonlinear modulation of the first optical signal nonlinearly modulated in accordance with a nonlinear characteristic of the optical fiber and a nonlinear modulation ratio of the first optical signal,
Wherein the pre-distortion section is nonlinear with a ratio opposite to the nonlinear modulation ratio on the basis of the linear signal, and the non-linearly modulated second optical signal corresponding to the non- Generating
Optical line terminal.
delete The method according to claim 1,
The pre-distortion unit generates the nonlinearly modulated second optical signal based on at least one of a distance between the optical line terminal and the subscriber terminal and a bandwidth of the first optical signal
Optical line terminal.
The method according to claim 1,
The transmission unit transmits the non-linearly modulated second optical signal to the subscriber terminal
Optical line terminal.
The method according to claim 1,
The nonlinearly modulated second optical signal is modulated into a linear signal according to the nonlinear characteristic of the optical fiber after passing through the optical fiber
Optical line terminal.
A receiver for receiving a first optical signal, which is a linear signal for confirming nonlinear modulation characteristics of the optical fiber from an optical line terminal through an optical fiber; And
And a transmission unit for transmitting a feedback signal related to a reception state of the first optical signal to the optical line terminal,
Wherein the feedback signal includes information indicating a degree of nonlinear modulation of the first optical signal that is nonlinearly modulated according to a nonlinear characteristic of the optical fiber and a nonlinear modulation ratio of the first optical signal,
The optical line terminal generates the non-linearly modulated second optical signal so as to be non-linear with respect to the linear signal and in a ratio opposite to the non-linear modulation ratio, and corresponds to the non-linearity degree
Subscriber terminal.
The method according to claim 6,
Wherein the receiving unit receives the second optical signal modulated nonlinearly from the optical line terminal
Subscriber terminal.
8. The method of claim 7,
Wherein the nonlinearly modulated second optical signal is generated by the optical line terminal based on at least one of a distance between the optical line terminal and the subscriber terminal and a bandwidth of the first optical signal,
After passing through the optical fiber, is modulated into a linear signal according to the nonlinear characteristic of the optical fiber
Subscriber terminal.
Transmitting a first optical signal, which is a linear signal for confirming nonlinear modulation characteristics of the optical fiber, to a subscriber terminal through an optical fiber;
Receiving a feedback signal associated with the first optical signal from the subscriber terminal; And
Generating a non-linearly modulated second optical signal based on the feedback signal,
Wherein the feedback signal includes information indicative of a nonlinear modulation degree of the first optical signal that is nonlinearly modulated according to a nonlinear characteristic of the optical fiber and a nonlinear modulation ratio of the first optical signal based on the linear signal,
The step of generating the non-linearly modulated second optical signal includes:
Linearly modulating the second optical signal to produce a non-linearly modulated second optical signal that is non-linear and opposite to the non-linear modulation ratio and corresponds to the non-linearity degree
A method of operating an optical line terminal.
delete 10. The method of claim 9,
Wherein the step of generating the nonlinearly modulated second optical signal comprises:
And generating the nonlinearly modulated second optical signal based on at least one of a distance between the optical line terminal and the subscriber terminal and a bandwidth of the first optical signal
A method of operating an optical line terminal.
10. The method of claim 9,
And transmitting the non-linearly modulated second optical signal to the subscriber terminal
A method of operating an optical line terminal.
10. The method of claim 9,
The nonlinearly modulated second optical signal is modulated into a linear signal according to the nonlinear characteristic of the optical fiber after passing through the optical fiber
A method of operating an optical line terminal.
Receiving a first optical signal that is a linear signal for confirming nonlinear modulation characteristics of the optical fiber from an optical line terminal through an optical fiber; And
And transmitting a feedback signal related to the first optical signal to the optical line terminal,
Wherein the feedback signal includes information indicating a degree of nonlinear modulation of the first optical signal that is nonlinearly modulated according to a nonlinear characteristic of the optical fiber and a nonlinear modulation ratio of the first optical signal,
The optical line terminal generates the non-linearly modulated second optical signal so as to be non-linear with respect to the linear signal and in a ratio opposite to the non-linear modulation ratio, and corresponds to the non-linearity degree
A method of operating a subscriber terminal.
15. The method of claim 14,
Further comprising the step of receiving a non-linearly modulated second optical signal from the optical line terminal
A method of operating a subscriber terminal.
16. The method of claim 15,
Wherein the nonlinearly modulated second optical signal is generated by the optical line terminal based on at least one of a distance between the optical line terminal and the subscriber terminal and a bandwidth of the first optical signal,
After passing through the optical fiber, is modulated into a linear signal according to the nonlinear characteristic of the optical fiber
A method of operating a subscriber terminal.

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