KR102280120B1 - Multilevel passive optical network transceiver with multiple wavelength switching function and wavelength switching method thereof - Google Patents

Abstract

The present invention relates to a multilevel PON transmission and reception device with a multiple wavelength switching function, which can automatically detect wavelength switching at an optical input/output end before a MAC processing unit, thereby performing quick switching, and minimizing a clock restoration delay in accordance with a multilevel signal, and a wavelength switching method thereof. Instead of an expensive tunable filter having low yield and stability and high power consumption, arrayed waveguide grating (AWG) accurately distinguishing and outputting only an optically fixed wavelength, being cheap and small, and requiring no separate complicated environmental variable control is applied so that received light having a plurality of wavelengths is distinguished and output by wavelength. A wavelength-specific optical signal is received using a plurality of photodiodes. A wavelength selection and control unit automatically selects one of the received outputs of the plurality of photodiodes by selecting and identifying the wavelength selection information of received data. To reduce the clock restoring time for a multilevel optical signal, clock restoration is continuously performed for one of the plurality of wavelengths to create a reference clock. For other wavelengths, only a phase delay for the reference clock is adjusted, and the clock is restored. Therefore, the received wavelength can be automatically switched quickly and accurately without the wavelength-related control of the MAC processing unit, a clock restoration delay can be minimized, thereby reducing the cost of the transmission and reception device and driving power, and reliability can be increased, thereby activating the population of a multilevel multiwave PON method.

Description

Multilevel passive optical network transceiver with multiple wavelength switching function and wavelength switching method thereof

The present invention relates to a multi-level PON transceiver having a built-in multi-wavelength selective switching function and a method for converting the wavelength thereof, and to provide a stable multi-wavelength optical communication transceiver in an economical way, but automatically using the optical input/output terminal before the MAC processing unit The present invention relates to a multilevel PON transceiver having a built-in multi-wavelength selective switching function that detects switching and performs fast switching and minimizes clock recovery delay according to a multilevel signal, and a method of switching the wavelength thereof.

With the introduction of 5G mobile communication, the spread of high-quality services, and the spread of IoT (Internet of Things) equipment, the communication capacity required by the subscriber network is rapidly increasing. Accordingly, the bandwidth required for optical communication used in such subscriber networks and metro networks is also rapidly increasing.

Therefore, since it is difficult to support a desired bandwidth through optical communication using a single wavelength, the communication band of a single optical transmission path is extended by using multiple wavelengths.

Passive optical network (PON) technology, which is most widely used as a subscriber network technology in optical communication, is intended to construct a high-speed subscriber network, and is configured to handle simultaneous access of multiple subscribers through a time division method or a wavelength division method. Recently, both time division method and wavelength division method are used. EPON (Ethernet PON) according to IEEE (Institute of Electrical and Electronics Engineers) 802.3av/ah or ITUT (International Telecommunication Union-Telecommunication Standardization Sector) G.984/7/ GPON (Gigabit PON), NG-PON (Next-Generation PON), and NG-PON2 according to 8/9 are representative examples.

Looking at the configuration of this PON, basically one OLT (Optical Line Terminal) installed in the telephone company and ONT (Optical Network Terminal) or ONU (Optical Network Unit) of multiple subscribers are passive optical branching devices called Remote Nodes. It has a point-to-multipoint network structure (using an optical splitter).

In the basic configuration of the PON, as shown in FIG. 1 , the OLT 10 and the ONT 20 are connected through an optical line, and direct communication through the optical line is performed by the transceivers 11 and 21 .

In the case of a PON using multiple wavelengths, each transceiver device must be able to transmit optical signals with a plurality of supported wavelengths and receive optical signals with a plurality of supported wavelengths.

For example, as a wavelength for transmission, for example, λ0 is 1532.68 nm, λ1 is 1533.47 nm, λ2 is 1534.25 nm, and λ3 is 1535.04 nm as a wavelength for transmission, and λ4 is a wavelength for reception. 1596.34nm, λ5 is 1597.19nm, λ6 is 1598.04nm, λ7 is 15989.89nm, and so on.

In this case, the OLT should be able to simultaneously transmit and receive signals of multiple wavelengths using a plurality of laser diodes and a plurality of photodiodes, and in the case of the ONT, transmit at one selected wavelength among a plurality of wavelengths, and also select one of the plurality of wavelengths. It must be received on one wavelength. A tunable laser diode that can select a desired wavelength is applied to the laser diode of such a transceiver, and a tunable filter that can receive only an optical signal for a specified wavelength is applied, and only the optical signal passing through it is converted to a photodiode. will receive

In the case of such a tunable filter, a method of selecting a filtering wavelength by varying the temperature of the etalon material is used. However, since the etalon filtering wavelength control according to temperature is non-linear, it is difficult to control for accurate filtering wavelength selection, and the optical loss is large. , the power required for temperature control is also a relatively large problem. In particular, there is a problem in that temperature control is very difficult depending on external conditions such as an industrial temperature change range (-40 to 85°C) under conditions that satisfy a wavelength filter of 0.8 nm. In the case of NGPON2, in order to provide a stable 0.8nm wavelength filter range, additional circuit configuration such as temperature compensation and measurement of the wavelength change of the wavelength filter is essential, and it is very difficult to secure stability due to various feedback circuit configurations.

In particular, in the case of such a tunable filter, since the yield is extremely low, the price is very high, and it is not easy to obtain a stable supply, there is a serious problem in terms of cost and stability. Furthermore, such a conventional tunable filter has a long delay time required for physical temperature control and stabilization for wavelength conversion, and there is a performance limitation that requires a considerably long time in the resynchronization process between OLT-ONTs after such wavelength conversion.

In NG-PON2, classes are classified according to the time required for wavelength conversion, and Class 3 for general use requires conversion time to an arbitrary wavelength within 25ms to 1 second. In the case of a high class, a wavelength can be changed with a delay of several milliseconds or hundreds of microseconds, but for this purpose, a more expensive tunable filter is required, so there is a limitation of low economic efficiency.

Therefore, in a multi-wavelength PON configuration that requires a tunable transceiver such as NG-PON2, which is of recent interest, it takes a long time to disperse some ONTs to other wavelengths when the communication load for a specific wavelength increases. There is a problem in that communication becomes unstable.

2 shows a PON-Ethernet converter 100 of a small form factor (SFP) format connected to an Ethernet port of an ONT as a transceiver capable of multi-wavelength communication, and transmits an electrical signal to a plurality of wavelengths (eg, λ0 to λ3) A laser diode transmitter 110 that converts one of the optical signals, a photodiode receiver 120 that generates an electrical signal by receiving an optical signal received at one of a plurality of wavelengths (eg, λ4 to λ7), and transmit data thereto and a media access control (MAC) device 130 that provides and collects received data and converts it into an Ethernet protocol.

Here, the laser diode (LD) transmitter 110 includes a tunable laser diode 111 capable of generating an optical signal by selecting one of a plurality of wavelengths and a driver 112 driving the same, and a normal voltage The output wavelength can be selected by controlling the temperature. The tunable laser diode 111 and the driver 112 have the stability and reliability of the wavelength control technology through the laser wavelength characteristic according to the temperature and the TEC (Thermo-Electric-Cooler), and the cost thereof has also reached the stabilization stage. In the case of the 10Gbps class, the technology is at a stage where it is universal, and thus the obstacles to technology introduction have been resolved in terms of economic feasibility.

The photodiode receiver 120 transmits only a selected wavelength among a plurality of wavelengths and filters the other wavelengths, and a tunable filter 121 for receiving an optical signal selectively transmitted through the tunable filter 121 is avalanche photo. The diode 122, a transimpedance amplifier 123 that amplifies while converting the current of the photodiode into a voltage, and the optical signal corresponding voltage amplified by the transimpedance amplifier 123 are compared with a reference voltage and converted into a digital corresponding voltage. and a limit amplifier 124 for amplifying.

Here, since the tunable filter 121 has to selectively transmit only one of a plurality of wavelengths selected in a similar band and block other wavelengths, high optical properties are required, so there is a problem of excessively high cost due to low yield, and optical properties based on temperature It consumes excessive power instantaneously by adjusting the temperature, and it is difficult to control and the stabilization time is long because it is necessary to filter the wavelength with a difference of 0.8 nm according to the temperature control. Furthermore, since the PON-Ethernet converter 100 is configured in a shape that supports SFP, miniaturization of the transmission/reception configuration is required. Since the existing etalon filter-based tunable filter 121 has relatively large parts, There is also a problem that it is not easy to deploy according to the SFP standard.

On the other hand, in this wavelength conversion process, the MAC device 130 that has received the wavelength conversion message provided from the OLT interprets the message, stops transmitting and receiving, and the tunable filter 121 and the tunable laser diode 111 for wavelength conversion. ), when the transmission/reception of the desired wavelength becomes possible, the synchronization procedure is performed while exchanging information with the OLT using the converted wavelength, so the physical wavelength conversion delay of the tunable elements for wavelength conversion There is also a problem in that the reliability of communication quality is lowered by the accumulation of the wavelength conversion delay in software that checks the wavelength conversion and controls the wavelength conversion.

In addition to the method using a plurality of wavelengths, there is a method using multi-level optical communication as another method for extending a communication band. Currently, most optical communication uses the NRZ (Non Return to Zero) modulation method that divides the optical signal strength into two stages, '1' or '0', but NRZ communication is used for ultra-wideband communication of 25, 50, and 100 gigabytes. In case of using it, there is a difficulty in development due to the bit conversion time in ultrasecond units at the femtosecond level. Due to this background, several studies have recently been conducted to apply a modulation method (eg, PAM (Pulse Amplitude Modulation) 4 or PAM 8, etc.) using a multi-level optical signal that can transmit multiple data through a single signal transmission. is in progress

When using such a multi-level optical signal, the transmitter laser diode has characteristic curves for the threshold current (Ith), the slope of the output according to the input current, and the saturation current (Isat), which are different for each manufacturer and individual product. In addition, as the temperature increases, the characteristic curve changes such as the threshold current increases and the slope decreases.

In the case of a photodiode that needs to receive the output of a laser diode having such a deviation through an optical path and classify it according to a level, the photocurrent output characteristic according to the received optical power is also different for each manufacturer and individual product. In particular, for high-speed signal reception of Gbps or higher, an avalanche photodiode (APD) with high efficiency and sensitivity and capable of high-speed operation is used. Since it operates in this way, it has different reception characteristics even with a slight process deviation.

Therefore, in the case of multi-level optical communication, the burden of accurate reception is greater than that of transmission. It is necessary to clearly distinguish multi-level signals (eg, 4 types for PAM4 and 8 types for PAM8) from the received optical signals. Correct data decoding is possible only by restoring the clock.

To this end, the multi-level optical receiver converts and amplifies (TIA) the photocurrent received by the avalanche photodiode (APD) into voltage, then accurately restores the clock from the signal (CDR: Clock Data Recovery), and then based on the recovered clock. It is necessary to decode the received multilevel signal to generate m-bit data.

Accordingly, there is a considerable delay for clock recovery until accurate reception data is recovered from the received optical signal.

This may not significantly affect the overall communication quality in the case of short-wavelength optical communication, but in the case of using multi-level optical signals and multi-wavelengths, a significant clock recovery delay occurs whenever the wavelength is changed. When combined with the accumulation of the wavelength conversion delay in software that controls the wavelength conversion by checking the wavelength conversion and the physical wavelength conversion delay of the tunable elements for conversion, the delay burden due to the wavelength conversion becomes excessive.

As described above, the tunable transceiver for multi-wavelength optical communication that supports multi-level for bandwidth extension has an excessively high cost, low reliability or system stability, and physical wavelength conversion delay of tunable devices and clock recovery according to the converted wavelength. Because the time delay is excessive, it is difficult to adequately distribute it despite the high demand due to the spread of 5G mobile communication.

Korean Patent Registration No. 10-2112785 [Title of the invention: Wavelength selection system and method for multi-wavelength passive optical network] Korean Patent Laid-Open Patent No. 10-2015-0068311 [Title of the invention: Optical transceiver of tunable ONU and transmission/reception method thereof] Korean Patent Registration No. 10-1541975 [Title of the invention: Optical communication receiver and chip used therein]

An object of the present invention to solve the above problems is to select and output only optically accurate wavelengths instead of a tunable filter. An inexpensive, compact, and no separate control is required for an Arrayed Waveguide Grating (AWG). applied so that the received light of a plurality of wavelengths is output separately for each wavelength, and an optical signal for each wavelength is received by a photodiode, and the wavelength selection control unit selects one of the outputs of the plurality of received photodiodes to select the wavelength selection information of the received data. In order to select and identify automatically, and to reduce the clock recovery time for multi-level optical signals, clock recovery is continuously performed on one wavelength among a plurality of wavelengths to generate a reference clock, and for other wavelengths, the reference clock is A multi-level PON transceiver with a built-in multi-wavelength selection switching function that automatically switches the reception wavelength and minimizes clock recovery delay without the control related to wavelength conversion of the MAC processing unit by adjusting only the phase delay so that the clock is restored, and its To provide a wavelength conversion method.

Another object of the present invention is to make the reception module and the clock data recovery unit of a wavelength performing clock recovery among multi-level optical signals always operate, and other wavelength-specific reception modules and decoders except for those corresponding to the selected wavelength, by shutting off the power. It is to provide a multilevel PON transceiver having a built-in multi-wavelength selective switching function to reduce power consumption and a method for converting the wavelength thereof.

Another object of the present invention is that the wavelength selection control unit selects a reception wavelength as well as performs wavelength conversion of a tunable laser diode according to the identification of wavelength selection information included in reception data, and the MAC processing unit re-synchronizes with the OLT Multi-level PON with built-in multi-wavelength selection switching function that minimizes delay due to wavelength conversion by performing wavelength conversion at the optical input/output terminal by itself even if the MAC processing unit does not perform control according to wavelength conversion by delivering a signal to perform It is to provide a transmitting and receiving device and a method for converting the wavelength thereof.

Another object of the present invention is to easily meet the SFP standard by applying an AWG that consumes excessive power and physically receives all of a plurality of wavelengths instead of a bulky temperature-controlled tunable filter, but is implemented in a small size on a glass substrate. To provide a multi-level PON transceiver with a built-in multi-wavelength selective switching function and a method for converting the wavelength of the device to reduce the device size of the light receiving part to enable device placement and reduce power consumption, thereby improving the design convenience for wiring and heat generation. .

A multi-level PON transceiver having a built-in multi-wavelength selection switching function according to an embodiment of the present invention includes an optical signal output unit that serializes transmission data and outputs a multi-level optical signal at a wavelength selected among a plurality of wavelengths, and a length for each wavelength Through an array type waveguide grating that divides and outputs a received optical signal by wavelength through an optical waveguide composed of An optical signal receiver configured to generate received data by converting an electric signal to an electric signal through ?, restoring a clock based on one of the electric signals for each wavelength, and decoding an electric signal of a selected wavelength through the restored clock; and the optical signal receiver. A MAC processing unit that receives received data from the optical signal output unit, outputs transmission data to the optical signal output unit, and synchronizes with OLT, and selects and identifies wavelength selection information from the received data generated by the optical signal receiving unit to determine the wavelength of the optical signal The receiving unit selectively decodes the electric signal corresponding to the wavelength to be converted from the electric signal for each wavelength and controls to generate received data, the optical signal output unit controls the optical signal output unit so that the output wavelength of the optical signal output unit becomes the converted wavelength, and the MAC processing unit and a wavelength selection control unit that provides an OLT synchronization request signal to the .

As an example, the optical signal receiver generates a reference clock by restoring a clock from an electrical signal of a preset reference wavelength among electrical signals for each wavelength, decodes the electrical signal of the reference wavelength using the reference clock, and parallelizes the received data a first decoder unit that generates , receives the reference clock generated by the first decoder unit, corrects only the phase delay, restores a clock corresponding to a specified wavelength, and uses the restored clock to generate a clock corresponding to the specified wavelength. A plurality of non-standard wavelength decoders that decode and parallelize an electrical signal to generate received data, and a decoder unit corresponding to the selected wavelength among the plurality of decoders transmit the received data generated by the decoder to the wavelength selection control unit, It may further include a selection decoding unit having a selection unit for outputting the received data of the decoder unit corresponding to the wavelength to be changed according to the control of the wavelength selection control unit.

As an example, the first decoder unit includes a clock data restoration unit for restoring a reference clock from an electrical signal received through a reference wavelength receiving module including an avalanche photodiode (APD) and a transimpedance amplifier (TIA). a decoder unit for restoring a multi-level signal included in an electrical signal received through the clock restored by the clock data restoration unit into data of a plurality of bits; It may include a parallelizer for generating received data by parallelizing the data restored by the decoder unit to the data length of the MAC processing unit.

As an example, the non-standard wavelength decoder unit is each configured for n-1 wavelengths out of n wavelengths used, and the non-standard wavelength decoder unit is composed of an avalanche photodiode and a transimpedance amplifier (TIA), so that Receives an electrical signal through a specified wavelength reception module that converts an optical signal into an electrical signal, receives the reference clock restored by the clock data recovery unit of the first decoder unit, and delays the phase of the reference clock according to the received electrical signal A phase delay unit for restoring a clock, a decoder unit for restoring a multi-level signal included in an electrical signal received through the clock restored by the phase delay unit into data of a plurality of bits, and the MAC processing unit for the data restored by the decoder unit It may include a parallelizer that generates received data by parallelizing it with a data length of .

Meanwhile, the reference wavelength reception module and the clock data recovery unit are always operated, and the selection unit may cut off power to the decoder unit and the reception module of the unselected wavelength under the control of the wavelength selection control unit.

As an example, the wavelength selection controller identifies only the 4-bit DWLCH ID field included in the PBSd (physical synchronization block downstream) field of the received data generated by the optical signal receiver to determine the downlink frame data wavelength identifier, and the downlink frame data wavelength is currently If it is different from the wavelength used, the PSBd analysis unit that selects the transmit/receive wavelength set according to the identified downlink frame data wavelength identifier after determining that the wavelength conversion is required state, and selects the receive wavelength corresponding to the transmit/receive wavelength set selected by the PSBd analysis unit a reception wavelength selection unit that generates a control signal for generating a control signal and provides it to the selection unit of the optical signal reception unit; and a control signal for selecting a transmission wavelength corresponding to the transmission/reception wavelength set selected by the PSBd analysis unit is generated and provided to the optical signal output unit and a synchronization signal providing unit that provides an OLT synchronization request signal to the MAC processing unit when the PSBd analysis unit determines that the wavelength conversion is required.

As an example, the MAC processing unit may be a single-wavelength PON MAC processing unit that does not have a wavelength conversion function for supporting multi-wavelength PON.

A wavelength conversion method of a multi-level PON transceiver with a built-in multi-wavelength selection switching function according to another embodiment of the present invention comprises an optical signal receiving unit, an optical signal transmitting unit, a MAC processing unit, and a wavelength selection control unit. As a wavelength conversion method, a multi-level optical signal of a plurality of wavelengths received through an arrayed waveguide grating that divides and outputs a received optical signal by wavelength through an optical waveguide composed of a length for each wavelength by an optical signal receiving unit is divided by wavelength; After converting the output multi-level optical signal for each wavelength into an electrical signal through the receiving module, the clock is restored based on one of the electrical signals for each wavelength, and the electrical signal of the selected wavelength is decoded through the restored clock to receive data. When the wavelength is changed by selectively identifying the wavelength selection information from the received data generated in the optical signal reception step and the wavelength selection control unit generated in the optical signal reception and reception step, electricity corresponding to the wavelength to be converted in the electrical signal for each wavelength of the optical signal reception unit A wavelength conversion step of selectively decoding a signal to generate received data, controlling the optical signal output unit so that the output wavelength of the optical signal output unit is a wavelength to be converted, and then providing an OLT synchronization request signal to the MAC processing unit; and performing synchronization with the OLT by the MAC processing unit receiving the OLT synchronization request signal provided by the selection control unit.

As an example, the optical signal receiving step includes a reference clock generation step of generating a reference clock by restoring a clock from an electrical signal having a preset reference wavelength among electrical signals for each wavelength, and using the reference clock when the wavelength used is the reference wavelength. Decoding an electrical signal converted from a multilevel optical signal received corresponding to a reference wavelength to generate received data, and if the wavelength used is not the reference wavelength, phase delaying the reference clock to restore the clock, Decoding an electrical signal converted from a multi-level optical signal received corresponding to the other selected wavelength through a clock to generate received data; and passing the received data generated according to the used wavelength to the wavelength selection control unit, The method may further include outputting the received data generated by using a wavelength to be changed under the control of the wavelength selection controller as a used wavelength.

As an example, the optical signal receiving step is a step of continuously maintaining the reference clock generation step and, when the used wavelength is changed, restoring the clock of a wavelength other than the used wavelength, and turning off the power of the components necessary for decoding and generating the received data. may include more.

A multi-level PON transceiver with a built-in multi-wavelength selection switching function and a wavelength conversion method according to an embodiment of the present invention accurately select only optically fixed wavelengths instead of expensive tunable filters with low yield and stability, high power consumption, and By applying an Arrayed Waveguide Grating (AWG) that is inexpensive, compact, and does not require separate control of complex environmental variables, it separates and outputs the received light of multiple wavelengths by wavelength, and separates the optical signal for each wavelength. In order to receive a photodiode and automatically select one of the received outputs of the plurality of photodiodes, the wavelength selection control unit selects and identifies the wavelength selection information of the received data, and also reduces the clock recovery time for a multi-level optical signal. A reference clock is generated by continuously performing clock recovery for one wavelength among a plurality of wavelengths, and in the case of other wavelengths, clock recovery is performed by adjusting only the phase delay of the reference clock, so that the MAC processing unit automatically restores the clock without any control related to wavelength conversion. It has the effect of enabling the spread of the multi-level multi-wavelength PON method by quickly and accurately converting the reception wavelength and minimizing the clock recovery delay to reduce the cost and driving power of the transceiver and increase reliability.

In addition, the multi-level PON transceiver having a built-in multi-wavelength selection conversion function and the wavelength conversion method according to an embodiment of the present invention are such that the reception module and the clock data recovery unit of the wavelength performing the clock recovery among the multi-level optical signals are always operated. In addition, there is an effect of increasing energy efficiency by reducing power consumption by shutting off power except for the wavelength-specific reception module and decoder unit corresponding to the selected wavelength.

In addition, the multi-level PON transceiver having a built-in multi-wavelength selective conversion function and the wavelength conversion method according to an embodiment of the present invention selects a reception wavelength as the wavelength selection control unit identifies wavelength selection information included in reception data; In addition, by transmitting a signal to perform wavelength conversion of the tunable laser diode and to perform synchronization with OLT again to the MAC processing unit, even if the MAC processing unit does not perform control according to the wavelength conversion, the optical input/output terminal performs wavelength conversion and There is an effect of improving the communication quality and increasing the compatibility of the MAC processing unit by minimizing the delay due to the wavelength conversion by performing the clock recovery according to the corresponding clock.

Furthermore, the embodiment of the present invention consumes excessive power and physically receives all of a plurality of wavelengths instead of a bulky temperature control type tunable filter, but by applying an AWG implemented in a small size on a glass substrate, it is easy to meet the SFP standard. It has the effect of reducing the device size of the light receiving part to enable device placement and reducing power consumption, thereby improving the design convenience for wiring and heat generation.

1 is a configuration example of a typical passive optical network.
2 is a block diagram of a conventional transceiver for tunable optical communication.
3 is a block diagram of an exemplary optical communication transceiver in a parallel manner.
4 is a block diagram of a multi-level PON transceiver having a built-in multi-wavelength selection switching function according to an embodiment of the present invention.
5 is a block diagram of a selection decoding unit according to an embodiment of the present invention;
6 is a block diagram of a wavelength selection control unit according to an embodiment of the present invention;
7 is a configuration diagram of downlink frame data checked for wavelength selection in an embodiment of the present invention;
8 is a flowchart illustrating a multi-wavelength selection switching function of a PON transceiver according to an embodiment of the present invention.

It should be noted that the technical terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. In addition, the technical terms used in the present invention should be interpreted as meanings generally understood by those of ordinary skill in the art to which the present invention belongs, unless otherwise defined in particular in the present invention. It should not be construed as meaning or in an excessively reduced meaning. In addition, when the technical term used in the present invention is an incorrect technical term that does not accurately express the spirit of the present invention, it should be understood by being replaced with a technical term that can be correctly understood by those skilled in the art. In addition, general terms used in the present invention should be interpreted as defined in advance or according to the context before and after, and should not be interpreted in an excessively reduced meaning.

Also, as used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In the present invention, terms such as "consisting of" or "comprising" should not be construed as necessarily including all of the various elements or several steps described in the invention, and some of the elements or some steps may not be included. It should be construed that it may further include additional components or steps.

Also, terms including ordinal numbers such as first, second, etc. used in the present invention may be used to describe the elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numerals regardless of reference numerals, and redundant description thereof will be omitted.

In addition, in the description of the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, it should be noted that the accompanying drawings are only for easy understanding of the spirit of the present invention, and should not be construed as limiting the spirit of the present invention by the accompanying drawings. Furthermore, in the detailed description of the present invention, an ONT (Optical Line Terminal) refers to a subscriber terminal and is substantially the same as an ONU (Optical Network Unit).

In the case of a tunable optical communication transceiver using a conventional etalon-based temperature-controlled tunable filter, it is large in size, low in yield, takes considerable time for temperature control, and consumes a lot of power. It is a big obstacle to the commercialization of the highly anticipated NG-PON2.

Several studies have been conducted to solve this problem, and the representative method is to configure the filter, photodiode, and MAC in parallel according to the number of wavelengths used instead of using an expensive and large temperature-controlled tunable filter.

For example, when configuring a tunable laser diode and a tunable filter (simply referred to as 'tunable configuration'), the cost is 4 sets of laser diode transmitters, 4 sets of photodiode receivers using fixed filters, and 4 sets of MAC processing units. It incurs a higher cost than the one (referred to simply as 'parallel configuration').

3 shows an exemplary configuration diagram of a transceiver 200 for optical communication in a parallel manner.

The illustrated configuration is an optical communication transceiver 200 that uses four different wavelengths for transmission and reception, respectively, and supports a 10 Gbps transmission/reception band for each wavelength.

The illustrated optical communication transceiver 200 may be applied to at least one of OLT and ONT of a multi-wavelength passive optical network including OLT and ONT, and a plurality of laser diode transmitters each operating at one transmission wavelength among the used wavelengths. 220, a fixed filter unit 210 in which a fixed filter that selectively transmits light of a single wavelength is configured as many as the number of wavelengths used, and an optical signal received through each fixed filter of the fixed filter unit 210 into electrical signals, respectively It includes a plurality of photodiode receivers 230 for conversion, a plurality of laser diode transmitters 220 and a plurality of MAC processors 240 that are connected to each of a pair of photodiode receivers 230 to transmit and receive data.

Here, the laser diode transmitter 220 includes a laser diode for outputting light of a previously fixed wavelength and a driver for driving the same, and transmits an electrical signal corresponding to the transmission frame data provided through the connected MAC processing unit 240 to the corresponding wavelength. output as an optical signal of

The photodiode receiver 230 internally includes a photodiode (typically an avalanche photodiode), a transimpedance amplifier that converts and amplifies the current of the photodiode into a voltage, and an optical signal corresponding voltage amplified by the transimpedance amplifier as a reference. After comparing with the voltage, it includes a limit amplifier amplifying to a corresponding digital voltage, and provides a signal amplified to a digital corresponding voltage through the limit amplifier to the connected MAC processing unit 240 .

The fixed filter unit 210 basically includes a fixed filter that transmits only a set wavelength among a plurality of reception wavelengths according to the configuration of the photodiode receiving unit 230 . Furthermore, as shown, an optical configuration for transmitting optical signals simultaneously output by the plurality of laser diode transmitters 220 to a single optical path may be included.

In the illustrated example, λ0 is 1532.68 nm, λ1 is 1533.47 nm, λ2 is 1534.25 nm, and λ3 is 1535.04 nm as the wavelength for transmission, and as the wavelength for reception, λ4 is 1596.34 nm, λ5 is 1597.19 nm, λ6 is 1598.04nm, λ7 is 15989.89nm can be selectively used, and it may be composed of four pairs of laser diode transmitter and photodiode receiver, and four MAC processing units 240 connected to each of them in pairs.

However, if such a parallel configuration of 4 sets is applied, it is not easy to configure a transceiver according to the SFP standard to support PON communication as an interface method that is connected to the Ethernet communication unit as a plug-in, so the problem of using the QSFP+/QSFP28 form factor arises. There is a limit to greatly lowering compatibility.

That is, in order to meet the industry's need for a PON transceiver that can be detached from the standard interface of Ethernet equipment in accordance with the SFP standard, this parallel method is also difficult to be an alternative.

On the other hand, when it is desired to extend the bandwidth using a multi-level optical signal as well as such multi-wavelength PON communication, each receiving unit 230 has an avalanche photodiode and a transimpedance amplifier ( TIA), a clock data recovery unit (CDR:Clock Data Recovery) for recovering the clock and data from the converted electrical signal, and a multi-level electrical signal through the clock recovered from the clock data recovery unit to decode the data (PAM4 is 2 bits) , PAM8 is 3 bits, etc.), the decoder must be configured.

Furthermore, since a plurality of transceivers and MAC processing units are configured in parallel and power consumption is severe, the power of the transceiver and MAC processing units of unused wavelengths must be cut off. Therefore, in the case of the illustrated parallel configuration, the wavelength is changed every time the wavelength is changed. There is a delay for recovering the clock after the changed wavelength is stabilized.

In particular, in the case of a multi-level optical signal, since it consists of a plurality of symbols (for example, '00', '01', '10', '11' in the case of PAM4), the circuit configuration for clock recovery is complicated and difficult, and such clock recovery performance is the most become an important factor. Therefore, a very long delay occurs in a stable CDR for a multilevel optical signal.

As a result, the multi-wavelength PON transceiver using multi-level optical signals has problems such as unstable yield, high cost, excessive volume, high power consumption, and excessive delay.

The present invention utilizes a tunable laser-based optical transmitter with a relatively stable supply and secured performance as it is, but instead of a temperature-controlled tunable filter using a conventional etalon, which caused various problems, it transmits optical signals for each wavelength without separate control. It utilizes an optical receiver using an optically separable Arrayed Waveguide Grating (AWG), and allows the optical input/output terminals (transmitter and receiver) at the front of the MAC processing unit to automatically switch wavelengths. Through the conversion, communication performance and stability can be improved. Furthermore, since the MAC processing unit does not perform the function for multi-wavelength selection switching, the PON-Ethernet MAC processing unit without such a function can be used as it is, which has the effect of greatly improving compatibility and design convenience.

In addition, it is possible to reduce the delay due to wavelength conversion by greatly improving the clock recovery speed according to wavelength conversion while extending the bandwidth using multi-level optical signals.

4 is a block diagram of a multi-level PON transceiver 300 having a built-in multi-wavelength selection switching function according to an embodiment of the present invention.

As shown, the configuration is concise as an optimal level configuration that excludes repetitive or overlapped configurations, unlike the parallel method, so there is no problem in placement in a limited space according to the SFP standard, and there is no high-power part, so heat dissipation However, the burden on wiring can also be greatly reduced.

The PON transceiver 300 according to the illustrated exemplary embodiment is installed in the ONT 20 and operates as a PON-Ethernet conversion device that performs conversion between PON communication and Ethernet communication. It is detachably coupled to the standard interface and supports Ethernet equipment to perform long-distance high-speed communication in the PON method.

As shown, it may include a terminal optical configuration such as a selective reflector or a reflector for matching the optical path with the transmitter and the receiver by separating the transmitted and received light, which may be configured in various ways and means other than the illustrated configuration.

The illustrated configuration according to the embodiment of the present invention is largely composed of an optical signal output unit 301 , an optical signal receiving unit 302 , and a wavelength selection control unit 360 , and an optical input/output terminal and a MAC processing unit that converts a PON communication format and an Ethernet format. (390).

Looking at this configuration in more detail, the illustrated embodiment converts transmission data into multi-levels (for example, in the case of PAM4, converts data in a 32-bit word state into a 2-bit serial signal, and then generates a corresponding driving voltage, etc.) An optical signal output unit 301 for outputting a multi-level optical signal at a wavelength selected from among the wavelengths of , and an array type waveguide grating (AWG) 330 for outputting a received optical signal by dividing it by wavelength through an optical waveguide configured with a length for each wavelength ), the received multi-level optical signal of a plurality of wavelengths is output separately for each wavelength, the output multi-level optical signal for each wavelength is converted into an electrical signal through the receiving module 340, and then one of the electrical signals for each wavelength is used as a reference The optical signal receiver 302 restores a clock to , and generates received data by decoding an electrical signal of a selected wavelength through the restored clock, and receives the received data from the optical signal receiver 302 and receives the optical signal output unit The MAC processing unit 390 that outputs the transmission data to 301 and performs synchronization with the OLT, and the optical signal reception unit 302 selectively identify wavelength selection information from the reception data generated by the optical signal reception unit 302, and when the wavelength is changed, the optical signal reception unit ( The optical signal output unit 302 selectively decodes the electrical signal corresponding to the wavelength to be converted from the electrical signal for each wavelength to generate received data, and the optical signal output unit so that the output wavelength of the optical signal output unit 301 becomes the converted wavelength. and a wavelength selection control unit 360 that controls the 301 and provides an OLT synchronization request signal to the MAC processing unit 390 .

In the illustrated embodiment, λ0 is 1532.68 nm, λ1 is 1533.47 nm, λ2 is 1534.25 nm, λ3 is 1535.04 nm as a wavelength for transmission, and as a wavelength for reception, λ4 is 1596.34 nm, λ5 is 1597.19 nm, λ6 can selectively use 1598.04 nm, λ7 can selectively use 15989.89 nm, and multilevel can transmit 2-bit information at a time through symbols of '00', '01', '10', and '11' using PAM4. .

On the other hand, since the transmission and reception wavelengths are configured and used as a limited set of wavelengths instead of using each arbitrarily, wavelength set information to be converted can be known by checking the identification information of the wavelength to be used next through the downlink frame data.

For example, wavelength set 1 is [transmission λ0 (1532.68 nm), reception λ4 (1596.34 nm)], set 2 is [transmission λ1 (1533.47 nm), reception λ5 (1597.19 nm)], and set 3 is [transmission λ2 (1534.25 nm)) , reception λ6 (1598.04 nm)], set 4 may be set to [transmission λ3 (1535.04 nm), reception λ7 (15989.89 nm)].

Furthermore, the array type waveguide grating (AWG) 330 used in the embodiment of the present invention is a physical configuration of an optical waveguide on a silica substrate. The optical signals passing through the optical waveguide can be distinguished and output with relatively high efficiency, and the size is very small as it is implemented through a semiconductor process. Therefore, when the arrayed waveguide grating (AWG) 330 is applied, the arrangement convenience within the limited SFP standard is higher and reliability and performance can be improved compared to the conventional fixed filter array or the temperature-controlled tunable filter.

The illustrated optical signal receiver 302 includes an arrayed waveguide grating (AWG) 330 that divides and outputs a received optical signal by wavelength through an optical waveguide having a length for each wavelength on a glass substrate, and an arrayed waveguide grating ( It includes a receiving module 340 that converts a multi-level optical signal that is divided and output for each wavelength through 330 into an electrical signal, and the receiving module 340 includes an avalanche photodiode and a transimpedance amplifier (TIA) provided for each wavelength. can do.

Furthermore, the optical signal receiving unit 302 includes a selective decoding unit 350 that restores a clock based on one of the electrical signals for each wavelength and then decodes the electrical signal of the selected wavelength through the recovered clock to generate received data. do.

5 shows the configuration of the selection decoding unit 350 according to an embodiment of the present invention.

The shown selective decoding unit 350 is connected to the receiving module 340 for converting a multi-level optical signal into an electrical signal for each wavelength, and the wavelength-specific decoders 351 to 354 configured in the selective decoding unit 350 are wavelength-specific. Each of the star receiving modules 341 to 344 is connected.

Here, a decoder unit connected to a preset reference wavelength (eg, λ4, reception channel No. 1) among the electric signals for each wavelength is used as the first decoder unit 351 to distinguish it from the other decoder units 352 to 354 .

The illustrated first decoder unit 351 (set to correspond to channel 1 in the illustrated example) restores a clock from an electrical signal to generate a reference clock, and decodes the electrical signal of the reference wavelength using the reference clock. After parallelization, the received data is generated, and the decoder units 352 to 354 corresponding to wavelengths other than the first decoder unit 351 receive the reference clock generated by the first decoder unit 351 and receive only the phase delay. A clock corresponding to a specified wavelength is restored by correction, and a specified wavelength using the recovered clock (eg, λ5 for the second decoder unit 352, λ6 for the third decoder unit 353, and λ6 for the fourth decoder unit 354) After decoding an electrical signal corresponding to λ7) (2 bits because it is PAM4 in the embodiment of the present invention), the received data is generated by parallelizing it with a word size (eg, 32 bits) used by the MAC processing unit 390 .

Furthermore, the illustrated selection unit 355 transmits the received data generated by the decoder unit corresponding to the selected wavelength (currently used or used wavelength) among the plurality of decoder units 351 to 354 to the wavelength selection control unit 360, The received data of the decoder unit corresponding to the wavelength to be changed according to the control of the wavelength selection control unit 360 is output to the MAC processing unit 390 .

The illustrated first decoder unit 351 receives a multi-level optical signal of a wavelength designated as a reference wavelength (λ4 in the illustrated example) among wavelength-specific reception modules composed of an avalanche photodiode (APD) and a transimpedance amplifier (TIA). Receives an electrical signal through the reference wavelength receiving module 341.

The first decoder unit 351 includes a clock data recovery unit 351a that recovers a reference clock from the received electrical signal, and a multilevel included in the electrical signal received through the clock data recovery unit 351a using the reference clock recovered from the clock data recovery unit 351a. The decoder unit (in the illustrated example, the PAM4 decoder unit, 351b, which restores the signal to data of multiple bits) restores the signal to data of multiple bits, and the data restored by the decoder unit 351b is the data length of the MAC processing unit 390 (for example, 32-bit word) and a parallelizer 351c for generating received data.

The non-standard wavelength decoder units 352 to 354 are respectively configured for n-1 wavelengths out of n used wavelengths (3 out of 4 wavelengths in the illustrated example), and the non-standard wavelength decoder units 352 to 354 are respectively configured. is composed of an avalanche photodiode (APD) and a transimpedance amplifier (TIA) to convert an optical signal of a specified wavelength other than the reference wavelength into an electrical signal (342 to 344, respectively λ5 to λ7 are designated) A phase delay unit for receiving an electrical signal through the receiver, receiving the reference clock restored by the clock data recovery unit 351a of the first decoder unit 351 and delaying the phase of the reference clock according to the received electrical signal to restore the clock (352a, 353a, 354a), and the phase delay unit (352a, 353a, 354a), a decoder unit for restoring the multi-level signal included in the electrical signal received through the recovered clock to data of a plurality of bits, and in the decoder unit and a paralleler for generating received data by parallelizing the restored data with the data length of the MAC processing unit.

On the other hand, in order to reduce power consumption, the selection unit 355 reduces power consumption of unnecessary components through a signal P for shutting off the power of the reception module and the decoder unit related to the wavelength not selected by the wavelength selection control unit 360 .

However, the clock data restoration unit 351a of the corresponding first decoder unit 351 and the reference wavelength receiving module 341 connected thereto always operate to maintain a state in which the reference clock is restored. Therefore, in order to reduce power consumption, even if the power of the receiving modules 342 to 344 or the decoders 351 to 354 for the wavelength not selected by the selection unit 355 is cut off, the clock data of the first decoder unit 351 is restored. The unit 351a and the reference wavelength receiving module 341 always operate regardless of this.

This means that the clock and data recovery unit 351a always provides the reference clock for the reference wavelength even when the selected wavelength is changed to a wavelength other than the reference wavelength, and the multi-wavelength optical signal received from substantially the same OLT is Since the clocks of downlink frame data received in multiple wavelengths because they are synchronized to the same OLT clock are substantially the same with only a slight phase delay for each wavelength, if the reference clock for the reference wavelength is accurately synchronized and restored, it is For clock recovery, only the phase needs to be slightly adjusted using the corresponding reference clock.

Accordingly, although the clock data recovery unit 351a is present in the first decoder unit 351 as shown in the illustrated configuration, the non-standard wavelength decoder units 352 to 354 have phase delay units 352a and 353a instead of the clock data recovery units. , 354a) is provided.

In the phase delay units 352a, 353a, and 354a, a plurality of delay elements for delaying a phase are configured in series, and a restored clock may be selected from the outputs of the delay elements, and it is sufficient to check the phase delay only once. That is, since the OLT transmits an optical signal for each wavelength using its own clock, the phase delay of other wavelengths with respect to the reference wavelength has a fixed value. Accordingly, the non-reference wavelength decoders 352 to 354 delay the reference clock provided by the clock data recovery unit 351a through each of the phase delay units 352a, 353a, and 354a to restore the correct synchronization clock at each wavelength. Since the phase delay value for each star can be fixed, and from then on, when the wavelength is changed, it is enough to apply its own phase delay fixed to the reference clock, so a delay for clock recovery is hardly generated.

On the other hand, since the plurality of wavelengths used have slightly different phase delays by 0.8 nm intervals, it is preferable to select the wavelength with the least phase delay (relatively faster in phase compared to other wavelengths) as the reference wavelength. , the phase of the clock obtained from the optical signal received with a different wavelength has a slight delay compared to the reference clock obtained from the optical signal received with the reference wavelength, so the clock is restored through the phase delay units 352a, 353a, 354a. can do.

For example, the phase delay units 352a, 353a, and 354a obtain a reference clock delayed through a plurality of series-connected phase delay elements, respectively restore data for a predetermined period based on this, and then integrate the restored data to obtain the largest The clock used for the restored data from which the value is obtained can be determined as the restored clock. If the output of the phase delay element providing the restored clock is determined, the process of determining the phase delay element is omitted from the next step and the output of the determined phase delay element is used. You can use it as is.

Accordingly, the selective decoding unit 355 can quickly change the used wavelength even when the selected wavelength is changed by the wavelength selection controller 360 , and accordingly, the wavelength conversion element delay or clock synchronization delay for the changed wavelength is also almost generated. I never do that.

The illustrated optical signal output unit 301 converts a temperature according to an applied control voltage to vary an output wavelength (TEC), and a driving power for optical output to the tunable laser diode 310 and the tunable laser diode 310 . Receives the parallel transmission data output by the driver 320 and the MAC processing unit 390 and converts it into a serial signal (m bits for generating a multi-level optical signal, 2 bits in the case of PAM4) to the driver 320 It includes a serializer 370 to provide.

The illustrated tunable laser diode 310 is a diode generating a laser optical signal in a predetermined wavelength range, and a temperature control means for receiving a signal instructing wavelength conversion and varying the temperature through an appropriate voltage to determine the output wavelength of the diode and a preparation signal providing means for providing a preparation completion signal indicating that the change of the wavelength is completed to the MAC processing unit when the target temperature is reached.

The MAC processing unit 390 may start synchronization for the OLT after receiving the ready signal provided by the tunable laser diode 310 .

As described above, since the optical signal receiving unit 302 hardly generates a delay for wavelength conversion, only the wavelength conversion for the tunable laser diode 310 is performed, and the synchronization procedure using the OLT and the changed wavelength can be performed immediately. Communication delay due to wavelength conversion can be minimized. In particular, since wavelength conversion is performed based on the electrical selection method, it can satisfy the wavelength conversion request time of several microseconds (Class A) required by NG-PON2.

The wavelength selection control unit 360 according to the embodiment of the present invention identifies only the 4-bit DWLCH ID field included in the physical synchronization block downstream (PBSd) field of the reception data generated by the optical signal reception unit 302 to identify the downlink frame data wavelength identifier. After determining whether to switch the transmission/reception wavelength set by identifying the wavelengths used by the optical signal receiving unit 302 and the optical signal outputting unit 301 accordingly, the OLT synchronization request signal is transmitted to the MAC processing unit 390 to transmit the wavelength Manage the transition process.

The embodiment of the wavelength selection control unit 360 is the same as the configuration of FIG. 6 . Such a configuration is merely divided into functional blocks for convenience of description, and actual implementation may be variously changed.

As shown in FIG. 6 , the wavelength selection control unit 360 interprets the PBSd field of the received data to determine the downlink frame data wavelength identifier, and if the downlink frame data wavelength is different from the currently used wavelength, it is determined that the wavelength conversion is required. A PSBd analysis unit 361 that selects a transmission/reception wavelength set according to the identified downlink frame data wavelength identifier, and a control signal for selecting a reception wavelength corresponding to the transmission/reception wavelength set selected by the PSBd analysis unit 361 The reception wavelength selection unit 362 provided to the selection unit 350 of the signal reception unit 302 and the PSBd analysis unit 361 generate a control signal for selecting the transmission wavelength corresponding to the transmission/reception wavelength set selected by the optical signal. The transmission wavelength selection unit 363 provided to the output unit 301 and the synchronization signal providing unit 364 providing the OLT synchronization request signal to the MAC processing unit 390 when the PSBd analysis unit 361 determines that the wavelength conversion is required. ) is included.

The illustrated PSBd analysis unit 361 identifies the wavelength information used in the received downlink frame data, and the downlink frame data according to the embodiment of the present invention has the same configuration as in FIG. 7 .

The illustrated configuration of FIG. 7 shows the downlink frame data configuration of ITUT-G.989.3. As shown, one downlink frame data includes a PSBd (Physical Synchronization Block, downstream) field corresponding to a header and a physical frame payload field. The PSBd consists of 8 bytes of synchronization data (Psync), 8 bytes of sequence number information (SFC: SuperFrame Counter structure), and 8 bytes of operation control information (OC: Operation Control structure).

Among these configurations, if you look at the structure of the operation control information, a 51-byte PON OC Body field is included, and if you look inside it, an 8-bit PIT (PON-ID Type) field and a 32-bit PON-ID field are included, and the PON In the -ID field, there is a 4-bit DWLCH ID (Downstream WaveLength CHannel IDentification) field.

Since the corresponding DWLCH ID field includes wavelength channel identifier information used by downlink data as in its expression, the PSBd interpreter 361 calculates from the 37th bit to the 40th bit among the last 8 bytes (OC structure) constituting the 24 bytes of PSBd data. You only need to extract and check the 4 bit values up to the second bit.

Meanwhile, since the wavelength selection control unit 360 performs all the wavelength conversion operations at the front end of the MAC processing unit 390 as described above, the MAC processing unit 390 does not actually need to perform any wavelength conversion operations. In particular, since the process of re-synchronizing with the OLT after converting the wavelength is the same as the process of registering to the OLT through the initial synchronization process in the single-wavelength PON, the MAC processing unit 390 in the transceiver according to the embodiment of the present invention performs the multi-wavelength MAC processing for single-wavelength PON that does not have a wavelength conversion function for PON support is also acceptable. Through this, even if the MAC processing unit 390 uses the existing short-wavelength PON configuration as it is or is redesigned, the design can be carried out through the existing IP, so that the compatibility is high (that is, the use of an inexpensive and verified MAC) and design convenience can be increased. do.

8 is a flowchart illustrating a multi-wavelength selection switching function of a PON transceiver according to an embodiment of the present invention.

As shown, when the PON transceiver of the present invention connects to the OLT for the first time, the wavelength selection control unit selects a preset reference wavelength set to determine the wavelengths of the optical signal output unit and the optical signal reception unit, and the OLT synchronization request signal to the MAC processing unit provides

From this point on, the reference wavelength clock is restored for the multilevel optical signal, which continuously provides the reference clock.

After receiving the OLT synchronization request signal, the MAC processing unit performs a synchronization process (initialization process) using the OLT and an optical signal of a currently set wavelength.

Thereafter, the wavelength selection control unit receives the received data generated from the selected signal among the optical signals received by the optical signal receiving unit through the arrayed waveguide grating, identifies the DWLCH ID field included in the PSBd field of the received data, and includes the downlink Check whether the wavelength of the frame data is changed, and when the wavelength is changed, control to select the receiving module and the decoder corresponding to the changed wavelength among the wavelength-specific reception module and the wavelength-specific decoder unit provided in the optical signal receiving unit (receive wavelength selection signal transmission); After controlling the optical signal output unit (transmitting the transmission wavelength selection signal) so that the output wavelength of the optical signal output unit is the wavelength to be converted, the OLT synchronization request signal is provided to the MAC processing unit.

The optical signal reception step includes a reference clock generation step of generating a reference clock by restoring a clock from an electrical signal of a preset reference wavelength among the electrical signals for each wavelength, and a reference clock corresponding to the reference wavelength through the reference clock when the wavelength used is the reference wavelength. Decoding the electrical signal converted from the received multi-level optical signal to generate received data, and if the wavelength used is not the reference wavelength, phase delay the reference clock to restore the clock, and respond to the selected wavelength through the restored clock Decoding the electrical signal converted from the received multi-level optical signal to generate received data, and transmitting the received data generated according to the wavelength used to the wavelength selection control unit, and selecting the wavelength to be changed according to the control of the wavelength selection control unit It may include outputting the received data generated using the wavelength to be used.

Such a configuration of the present invention may be implemented through an optical device, an electronic device, and physical means such as a circuit board and an integrated circuit chip, many of which may be configured inside a programmable chip. Those of ordinary skill in the art to which the present invention pertains may modify and modify the above-described contents without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

10: OLT 20: ONT
300: PON transceiver 301: optical signal output unit
302: optical signal receiver 310: tunable laser diode
320: driving unit 330: arrayed waveguide grating
340: receiving module 350: selection decoding unit
360: wavelength selection control unit 370: serializer
390: MAC processing unit

Claims (10)

an optical signal output unit for serializing transmission data and outputting a multilevel optical signal at a wavelength selected from among a plurality of wavelengths through a tunable laser diode controlled according to a control signal for selecting a transmission wavelength;
Through an array-type waveguide grating that divides and outputs a received optical signal by wavelength through an optical waveguide composed of a length for each wavelength, a multilevel optical signal of a plurality of received wavelengths is divided and output for each wavelength, and a multilevel optical signal for each wavelength output is converted into an electrical signal through the reception module, and the clock is restored based on one of the electrical signals for each wavelength according to the control signal for selecting the reception wavelength, and the electrical signal of the selected wavelength is decoded and received through the recovered clock. an optical signal receiver for generating data;
a MAC processing unit for single-wavelength PON that receives received data from the optical signal receiving unit, outputs transmission data to the optical signal output unit, and synchronizes with the OLT, but does not have a wavelength selection function;
After selecting and identifying wavelength selection information by checking information contained in a specific field of the received data generated by the optical signal receiver, when the wavelength is changed, the optical signal receiver selects an electrical signal corresponding to the wavelength to be converted from the electrical signal for each wavelength provides a control signal for selecting a reception wavelength so as to generate reception data by decoding, and provides a control signal to the optical signal output unit such that the output wavelength of the optical signal output unit is a wavelength to be converted, and an OLT synchronization request signal to the MAC processing unit It includes a wavelength selection control unit that provides
The optical signal receiving unit
A first decoder unit for generating a reference clock by restoring a clock from an electrical signal of a preset reference wavelength among electrical signals for each wavelength, decoding the electrical signal of the reference wavelength using the reference clock, and parallelizing the electrical signal to generate received data Wow;
Receives the reference clock generated by the first decoder unit, corrects only the phase delay, restores a clock corresponding to a specified wavelength, decodes an electrical signal corresponding to the specified wavelength using the recovered clock, and parallelizes the reception a plurality of non-reference wavelength decoder units for generating data;
A selection of transmitting the received data generated by the decoder unit corresponding to the selected wavelength among the plurality of decoder units to the wavelength selection control unit, and outputting the received data of the decoder unit corresponding to the wavelength to be changed according to the control signal of the wavelength selection control unit A multi-level PON transceiver with a built-in multi-wavelength selection switching function, characterized in that it further comprises a selective decoding unit having a unit.
delete The method according to claim 1, wherein the first decoder unit
a clock data recovery unit configured to recover a reference clock from an electrical signal received through a reference wavelength reception module including an avalanche photodiode and a transimpedance amplifier (TIA);
a decoder unit for restoring a multi-level signal included in an electrical signal received through the clock restored by the clock data restoration unit into data of a plurality of bits;
and a parallel unit for generating received data by parallelizing the data restored by the decoder unit to the data length of the MAC processing unit.
The method according to claim 3, wherein the non-standard wavelength decoder unit is configured for n-1 wavelengths among n wavelengths used, respectively,
The wavelength decoder unit other than the above reference
The avalanche photodiode and transimpedance amplifier (TIA) receive an electrical signal through a specified wavelength receiving module that converts an optical signal of a specified wavelength other than the reference wavelength into an electrical signal, and the clock data recovery unit of the first decoder unit a phase delay unit for receiving the reference clock restored from the , and delaying the phase of the reference clock according to the received electrical signal to restore the clock;
a decoder unit for restoring a multi-level signal included in an electrical signal received through the clock restored by the phase delay unit into data of a plurality of bits;
and a parallel unit for generating received data by parallelizing the data restored by the decoder unit to the data length of the MAC processing unit.
4. The method according to claim 3, wherein the reference wavelength receiving module and the clock data recovery unit are always operated, and the selection unit cuts off power to the decoder unit and the receiving module of the unselected wavelength according to the control of the wavelength selection control unit. Multi-level PON transceiver with built-in multi-wavelength selection switching function.
The method according to claim 1, The wavelength selection control unit
The downlink frame data wavelength identifier is identified by identifying only the 4-bit DWLCH ID field included in the physical synchronization block downstream (PBSd) field of the received data generated by the optical signal receiver. If the downlink frame data wavelength is different from the currently used wavelength, the wavelength a PSBd analysis unit that selects a transmit/receive wavelength set according to the identified downlink frame data wavelength identifier after determining that the switch is required;
a reception wavelength selection unit that generates a control signal for selecting a reception wavelength corresponding to the transmission/reception wavelength set selected by the PSBd analysis unit and provides the control signal to the selection unit of the optical signal reception unit;
a transmission wavelength selection unit that generates a control signal for selecting a transmission wavelength corresponding to the transmission/reception wavelength set selected by the PSBd analysis unit and provides the control signal to the optical signal output unit;
A multi-level PON transceiver with a built-in multi-wavelength selection switching function, characterized in that it includes a synchronization signal providing unit that provides an OLT synchronization request signal to the MAC processing unit when the PSBd analysis unit determines that the wavelength conversion is required.
delete A wavelength conversion method of a multi-level PON transceiver device comprising an optical signal receiving unit, an optical signal output unit, a single-wavelength PON MAC processing unit without a wavelength selection function, and a wavelength selection control unit, comprising:
The optical signal receiver divides and outputs the multilevel optical signal of a plurality of wavelengths received through the array type waveguide grating that divides the received optical signal by wavelength and outputs it by wavelength through the optical waveguide composed of the length for each wavelength, and outputs the multi-level optical signal for each wavelength. After converting the level optical signal into an electrical signal through the reception module, the clock is restored based on one of the electrical signals for each wavelength according to the control signal of the wavelength selection control unit for selecting the reception wavelength, and selected through the restored clock an optical signal reception step of decoding an electrical signal of a wavelength to generate reception data;
An optical signal output step of outputting an optical signal at a selected wavelength among a plurality of wavelengths through a tunable laser diode controlled according to a control signal of the wavelength selection controller for selecting a transmission wavelength after the optical signal output unit serializes transmission data Wow;
When the wavelength is changed by selectively identifying wavelength selection information from the received data generated in the optical signal reception step, the wavelength selection control unit selectively decodes the electrical signal corresponding to the wavelength to be converted from the wavelength-specific electrical signal of the optical signal reception unit to receive data a wavelength conversion step of providing an OLT synchronization request signal to the MAC processing unit after providing a control signal to generate a control signal, providing a control signal to the optical signal output unit so that the output wavelength of the optical signal output unit becomes a wavelength to be converted;
and performing synchronization with the OLT by the MAC processing unit receiving the OLT synchronization request signal provided by the wavelength selection control unit,
The optical signal receiving step is
a reference clock generation step of generating a reference clock by restoring a clock from an electrical signal having a preset reference wavelength among the electrical signals for each wavelength;
generating reception data by decoding an electrical signal converted from a multilevel optical signal received corresponding to the reference wavelength through the reference clock when the wavelength used is the reference wavelength;
When the wavelength used is not the reference wavelength, the clock is restored by phase delaying the reference clock, and the electrical signal converted from the multi-level optical signal received corresponding to the selected wavelength different from the reference wavelength is decoded through the recovered clock. generating received data;
The method further comprising the step of transmitting the received data generated according to the used wavelength to the wavelength selection control unit, and outputting the received data generated by using the wavelength to be changed according to the control signal of the wavelength selection control unit as the use wavelength Wavelength switching method of multi-level PON transceiver with built-in multi-wavelength selective switching function.
delete The method according to claim 8, wherein the optical signal receiving step continuously maintains the reference clock generation step, and when the used wavelength is changed, a component necessary for recovering a clock of a wavelength other than the used wavelength, decoding, and generating received data. Wavelength conversion method of a multi-level PON transceiver with a built-in multi-wavelength selective conversion function, further comprising the step of turning off the power.

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