KR20170058297A - Registration method adjusting wavelength of optical network unit according to wavelength capability of optical transceiver of the optical network unit - Google Patents

Abstract

An OLT for efficiently using a plurality of wavelength channels and a registration method performed by an ONU can be provided. The OLT and the ONU can exchange displayed messages where wavelength output characteristics are displayed with each other. The ONU may include one among a fixed wavelength optical transceiver using only one wavelength, a variable wavelength optical transceiver for selecting and using one wavelength from a plurality of wavelengths, and a multi-wavelength optical transceiver for using at least one of the plurality of wavelengths at the same time. The OLT can identify the optical transceiver included in the ONU and determine a wavelength to be used by the ONU according to the characteristics of the identified optical transceiver. So, a plurality of wavelength channels can be efficiently used.

Description

TECHNICAL FIELD [0001] The present invention relates to a registration method for adjusting the wavelength of an ONU in accordance with a wavelength output characteristic of an optical transceiver of an optical network unit (ONU). BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical network unit

The present invention relates to a Passive Optical Network (PON).

A Passive Optical Network (PON) is classified as a Time Division Multiple Access (PON) that provides time division service and a WDM (Wavelength Division Multiplexing) PON that provides wavelength division services according to the transmission method. do. Current PONs use a point-to-multipoint link structure. The current PON uses a TDMA-PON scheme that transmits a signal using a broadcast scheme in a downward direction and transmits a signal in a TDMA scheme in an upward direction. Current PONs are classified into EPON (Ethernet PON) and GPON (Gigabit-capable PON) depending on which transmission protocol is used.

Since a plurality of ONUs (Optical Network Units) are connected to one OLT (Optical Line Terminal) in a point-to-multipoint manner, the OLT manages a plurality of connected ONUs. In particular, in an upward direction, the OLT must distribute the time for transmitting signals to a plurality of ONUs so that signals sent to the OLT by a plurality of ONUs do not collide with each other.

Recently, the IEEE 802.3 working group and the ITU-T Study Group 15 are performing standardization based on a TDM / WDM hybrid scheme that uses a mixture of TDM and WDM in order to support a transmission rate higher than that supported by the existing TDM-PON.

A next generation PON such as NG-EPON or TWDM-PON can use a plurality of WDM wavelength channels to transmit signals at a transmission speed of 40 Gb / s or higher. An ONU connected to such a TDM / WDM hybrid PON can communicate with the OLT using one or more wavelength channels and use the TDMA scheme.

In order to efficiently use a plurality of wavelength channels, the present invention proposes a registration method of an OLT and an ONU in which a target wavelength to be used by an ONU is set in consideration of a wavelength output characteristic of the ONU.

According to an embodiment of the present invention, there is provided a method of registering an optical network unit (ONU) performed by an optical line terminal (OLT), the optical network unit comprising: Transmitting a discovery gate message including wavelength information used in a passive optical network (PON) from a registration request message transmitted by the optical network unit corresponding to the discovery gate message, Determining a target wavelength to be used when the optical network unit transmits and receives a message to / from the optical line terminal, taking into consideration the wavelengths that can be supported by the optical network unit and the wavelengths used in the passive optical network A registration method including the steps of: A readable recording medium is provided.

According to one embodiment, the identifying step further comprises: from the registration request message, a registration method for identifying a type of optical transceiver included in the optical network unit or one or more wavelengths that the optical transceiver can output, There is provided a recording medium readable by a computer.

According to one embodiment, the determining step may include: when the optical transceiver variably selects one wavelength among a plurality of wavelengths that the optical network unit can support and transmits and receives the message, There is provided a computer-readable recording medium recording a registration method and a method for determining a wavelength used in a passive optical network and a wavelength included in a plurality of wavelengths that can be supported by the optical network unit.

According to one embodiment, the determining step may be configured such that, when the optical transceiver transmits and receives the message using a plurality of wavelengths simultaneously among a plurality of wavelengths that the optical network unit can support, There is provided a computer-readable recording medium recording a registration method and a method for determining the wavelengths used in the passive optical network and the wavelengths commonly included in a plurality of wavelengths that the optical network unit can support.

According to one embodiment, the transmitting step includes a registration method of transmitting the discovery gate message indicating the type of optical network unit that the optical line terminal can support, and a computer-readable recording medium recording the above-described method do.

According to one embodiment, the determining step comprises: a registration method for broadcasting the registration message in which the target wavelength is indicated, for transferring the target wavelength to the optical network unit; and a computer-readable recording medium recording the above- Is provided.

According to one embodiment, there is provided a method of transmitting a gateway message to an optical network unit, the method comprising: transmitting a gate message to the optical network unit to determine whether the optical transceiver of the optical network unit has activated a wavelength according to the target wavelength; There is provided a registration method and a computer readable recording medium recording the above-described method, further comprising the step of determining whether the optical transceiver is activated according to the target wavelength, using a transmitted Registration Acknowledgment Message .

According to an embodiment of the present invention, there is provided an optical line terminal comprising: an optical transceiver in communication with an optical line terminal (OLT) and a processor, the optical transceiver comprising: And the processor transmits a registration request message including information of the plurality of wavelengths to the optical line terminal in response to the discovery gate message transmitted by the optical line terminal, The target wavelength is selected in consideration of a wavelength used in a passive optical network (PON) to which the plurality of wavelengths and the optical line terminal are connected, using the registration message transmitted in response to the registration request message An optical network unit (ONU) is provided.

According to an embodiment of the present invention, there is provided an optical line terminal including: an optical transceiver communicating with an optical line terminal (OLT); and a processor, the optical transceiver communicating with the optical line terminal using a plurality of wavelengths at the same time, The processor transmits a registration request message including information on all wavelengths available to the optical transceiver to the optical line terminal in response to the discovery message transmitted by the optical line terminal, Considering a wavelength used in a passive optical network (PON) in which all the wavelengths available to the optical transceiver and the optical line terminal are connected, using the registration message transmitted in response to the request message, Optical Network Units (ONUs) are provided for selecting wavelengths.

In the process of registering the OLT and the ONU, since the target wavelength to be used by the ONU is set in consideration of the wavelength output characteristics of the ONU, a plurality of wavelength channels can be efficiently used.

1 is an exemplary diagram of a passive optical network in which a fiber line terminal according to an embodiment of the present invention is connected to different types of optical network units.
2 is a view for explaining a message transmitted and received by an OLT and an ONU in the process of registering an ONU with an OLT according to an embodiment of the present invention.
3 is a conceptual diagram illustrating a structure of a multi-wavelength optical transceiver of an ONU according to an embodiment of the present invention.
4 is a conceptual diagram illustrating a structure of a multi-wavelength optical transceiver of an ONU according to another embodiment of the present invention.
5 is a flowchart illustrating an operation performed by an OLT according to an exemplary embodiment of the present invention.
6 is a flowchart illustrating an operation performed by an ONU according to an exemplary embodiment of the present invention.

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

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

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

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

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

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

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

1 is a block diagram illustrating an optical line terminal (OLT) 120 according to an embodiment of the present invention. The optical line terminal 120 is connected to optical network units (ONU) 141, 142, Is an exemplary diagram of a passive optical network (PON).

Different kinds of ONUs 141, 142, and 143 can access the PON 110 through one OLT 120. [ The ONUs 141, 142, and 143 may be connected to the OLT 120 using an optical splitter 130. The device connected to the PON 110 may transmit signals upward and downward using at least one of a plurality of predetermined wavelengths. The OLT 120 and the ONUs 141, 142, and 143 may be connected through an optical cable. The OLT 120 and the ONUs 141, 142, and 143 may include an optical transceiver that performs conversion between an optical signal and an electrical signal. The target wavelength means the wavelength used by the optical transceiver.

1, the ONU 141 may include a wavelength fixed optical transceiver for transmitting and receiving an output wavelength to a wavelength channel included in a wavelength band designated by the upstream wavelength band of the PON 110. [ The OLT 120 can determine the wavelengths to be used by the ONUs 141, 142 and 143 in consideration of the fixed wavelengths used by the ONUs 141. [

According to one embodiment of the present invention, a wavelength fixed optical transceiver may include a fixed wavelength optical transmitter and an optical receiver capable of transmitting the output wavelength to a specific wavelength channel. The optical receiver may include a fixed filter capable of receiving only a specific wavelength channel. The transmission wavelength channel and the reception wavelength channel of the fixed wavelength optical transceiver may be included in the wavelength band where the chromatic dispersion value according to the wavelength of the single mode optical fiber is near 0. [ The transmission wavelength channel and the reception wavelength channel can be included in the wavelength band where the loss of the single mode optical fiber is within 0.3 dB / km. The transmitting wavelength channel and the receiving wavelength channel may be included in the same wavelength band, or may be included in different wavelength bands.

1, the ONU 142 is a wavelength tunable wavelength tunable optical transmission / reception unit capable of transmitting / receiving an output wavelength through a wavelength channel allocated by the OLT 120 among wavelength channels included in a wavelength band designated by the upstream wavelength band of the PON 110 And may include a wavelength tunable optical transceiver. That is, the wavelength used by the wavelength tunable optical transceiver of the ONU 142 can be adjusted by the OLT 120. The OLT 120 can determine the wavelength of the ONU 142 in consideration of the wavelength allocation state of the ONUs 141 and 143. The OLT 120 can select the wavelength of the ONU 142 as one of the wavelength channels included in the wavelength band designated by the upstream wavelength band.

The wavelength tunable optical transceiver of the ONU 142 can variably select the output wavelength channel and the reception wavelength channel out of the wavelength channels within the predetermined wavelength band. The wavelength tunable optical transceiver may include a wavelength tunable optical transmitter and a wavelength tunable optical receiver. The output wavelength channel and the reception wavelength channel of the wavelength tunable optical transceiver can be selected within a wavelength band in which the chromatic dispersion value according to the wavelength of the single mode optical fiber is near zero. Alternatively, the output wavelength channel and the receive wavelength channel of the tunable optical transceiver may be selected from two or more wavelength channels within a wavelength band where the loss of the single mode optical fiber is within 0.3 dB / km. The output wavelength channel and the reception wavelength channel may be selected in the same wavelength band, or may be selected in different wavelength bands. The tunable optical transmitter and the tunable optical receiver can select the wavelength channel using a thermooptic effect, an electrooptic effect, or a mechanical optic effect.

1, the ONU 143 includes a plurality of wavelength channels included in a wavelength band designated by the upstream wavelength band of the PON 110 and capable of transmitting and receiving output wavelengths through two or more wavelength channels, And may include a multi-wavelength optical transceiver. That is, the OLT 120 can select at least two wavelengths of the ONU 143 among the wavelength channels included in the wavelength band designated by the upstream wavelength band. For two or more wavelength channels determined by the OLT 120, the ONU 143 can simultaneously transmit and receive a plurality of messages through two or more determined wavelengths.

In other words, the OLT 120 may be configured such that each of the ONUs 141, 142, and 143 transmits (i) an optical transceiver that transmits and receives a message using a fixed wavelength, (ii) Or (iii) an optical transceiver that transmits and receives a message using a plurality of wavelengths at a wavelength that the ONU can support. The OLT 120 can determine the wavelength to be used by each of the ONUs 141, 142, and 143 using the detected result. The above-described operation can be performed in the process of each ONU 141, 142, 143 joining the PON 110 via the OLT 120.

2 is a diagram for explaining a message transmitted and received by the OLT 210 and the ONU 220 in the process of registering the ONU 220 in the OLT 210 according to an embodiment of the present invention. The OLT 210 and the ONU 220 can perform the operation of FIG. 2 in an ONU registration (Discovery Handshake Message Exchange) step. The OLT 210 and the ONU 220 may exchange wavelength capability information of each other.

Referring to FIG. 2, the ONU 220 is an ONU connected to the PON, and is assumed to be offline. The OLT 210 may broadcast a Discovery Gate MPCP message 230 so that the unregistered ONU 220 can transmit the registration request message 240 to the OLT 210. [ The discovery gate message 230 may include a Destination Address (DA) field indicating an address of an ONU to be received. The OLT 210 broadcasts the discovery gate message 230 so that a predetermined address value indicating that the message is broadcasted may be written to the recipient address field instead of the MAC address of the specific ONU 220 .

The discovery gate message 230 may include a source address (SA) field in which the MAC address of the OLT 210 is input. The discovery gate message 230 may include information about a discovery window or a quiet window that is a slot through which the ONU 220 transmits the registration request message 240 to a discovery information field, . As information on the discovery window, the discovery gate message 230 may include a starting time field of the discovery window and a length of the discovery window field.

The discovery gate message 230 may include information on a wavelength used in a PON connected to the OLT 210. More specifically, the discovery gate message 230 may include information on a wavelength channel supported by the OLT 210. [ Information on the wavelength channels supported by the OLT 210 may be included in the Discovery Information field.

The ONU 220 can use the recipient address field of the received discovery gate message 230 to know that the discovery gate message 230 has been broadcast. Since the OLT 210 broadcasts the Discovery Gate message 230, all ONUs connected to the OLT 210 may receive the Discovery Gate message 230. The ONU previously registered in the OLT 210 receives the discovery gate message 230 but may not transmit the registration request message 240 in response to the discovery gate message 230. Since the ONU 220 is not registered in the OLT 210, it can transmit the registration request message 240.

2, the ONU 220 transmits a registration request message (RESISTER_REQ Message) 240 from an assigned grant time to an arbitrary random number so that the OLT 210 receives the registration request message 240 in the discovery window. Lt; RTI ID = 0.0 > of < / RTI > The registration request message 240 may include a pending grant value, discovery information, a laser on time, and a laser off time.

Referring to FIG. 2, the registration request message 240 may include information on a wavelength channel supported by the ONU 220. More specifically, the information on the wavelength channel includes information on the type of optical transceiver (fixed wavelength optical transceiver, wavelength tunable optical transceiver, multi-wavelength optical transceiver) mounted on the ONU 220 and wavelength channels output by the optical transceiver . Information on the wavelength channel may be included in the Discovery Information field of the registration request message 240. [

The OLT 210 receiving the registration request message 240 can transmit a registration message 250 including the MAC address of the ONU 220 to the ONU 220. The registration message 250 may include an LLID value to be used by the ONU 220, a target laser on / off time. The registration message 250 may include wavelength channel information used in the PON system and information on a wavelength channel to be used by the ONU 220. [ The information on the wavelength channel to be used by the ONU 220 may be included in the wavelength channel map indicating the wavelength channel used in the PON system.

The ONU 220 may change the parameters of the optical transceiver included in the ONU 220 based on the registration message 250. [ That is, the ONU 220 can set the parameters of the optical transceiver so that the optical transceiver operates according to the information on the wavelength channel included in the registration message 220. [

2, the OLT 210 can unicast a gate message 260 to the ONU 220 in order to check whether the ONU 220 is normally activated. In other words, OLT 210 may send gate message 260 to ONU 220 to determine if ONU 220 operates in accordance with registration message 250.

The ONU 220 may transmit a registration acknowledgment message 270 to the OLT 210 in response to the gate message 260. The OLT 210 may use the registration confirmation message 270 to determine whether the ONU 220 operates in accordance with the registration message 250. If it is determined that the ONU 220 operates according to the registration message 250, the registration process of the OLT 210 and the ONU 220 may be terminated. Thereafter, the OLT 210 and the ONU 220 can transmit and receive a message using the set wavelength channel.

As described above, the OLT 210 can transmit information on the wavelength channels supported by the OLT 210 to the ONU 220 using the discovery gate message 230. On the contrary, the ONU 220 can transmit the information on the wavelength channel supported by the ONU 220 to the OLT 210 using the registration request message 240. That is, the OLT 210 and the ONU 220 may exchange information on usable wavelength channels. The wavelength channel to be used by the OLT 210 and the ONU 220 to transmit and receive messages may be determined based on the exchanged information. Accordingly, a plurality of ONUs having different wavelength output characteristics can be connected to one OLT 210. [ That is, the PON can accommodate a plurality of ONUs having different wavelength output characteristics.

3 is a conceptual diagram illustrating a structure of a multi-wavelength optical transceiver of an ONU according to an embodiment of the present invention.

The multi-wavelength optical transceiver of the ONU according to an exemplary embodiment may select two or more wavelength channels from a plurality of wavelength channels included in a predetermined wavelength band. A multi-wavelength optical transceiver may utilize two or more selected wavelength channels as an output wavelength channel and a received wavelength channel.

A multi-wavelength optical transceiver may include a multi-wavelength optical transmitter and a multi-wavelength optical receiver. The output wavelength channel and the receive wavelength channel of the multi-wavelength optical transceiver can be selected from two or more wavelength bands whose chromatic dispersion values along the wavelength of the single mode optical fiber are near 0 or in a wavelength band within 0.3 dB / km of loss of the single mode optical fiber . The output wavelength channel and the reception wavelength channel may be selected in the same wavelength band, or may be selected in different wavelength bands. The number of wavelength channels used by each of the multi-wavelength optical transmitter and the multi-wavelength optical receiver may be different from each other.

Referring to FIG. 3, the multi-wavelength optical transceiver may include two or more fixed wavelength optical transmitters 330 and two or more fixed wavelength optical receivers 350. The fixed wavelength optical transmitter 330 and the fixed wavelength optical receiver 350 may be devices that are integrated using array technology. A plurality of optical signals output by the two or more fixed wavelength optical transmitters 330 may be multiplexed by the multiplexing unit 320. The optical signal received through the optical fiber may be demultiplexed by the demultiplexing unit 340 and then transmitted to the two or more fixed wavelength optical receivers 350. The multiplexing unit 320 and the demultiplexing unit 340 may be implemented using an AWG (Arrayed Waveguide Grating) or a thin film filter.

The wavelength division multiplexing unit 310 may output the multiplexed optical signal through the optical fiber. The wavelength division multiplexing unit 310 may output the optical signal received through the optical fiber to the demultiplexing unit 340.

An ONU including a multi-wavelength optical transceiver may activate or deactivate two or more fixed wavelength optical transmitters 330 according to the registration message transmitted by the OLT. That is, the ONU may activate the fixed wavelength optical transmitters 330 corresponding to the plurality of wavelength channels designated through the registration message and deactivate the remaining fixed optical wavelength transmitters 330.

4 is a conceptual diagram illustrating a structure of a multi-wavelength optical transceiver of an ONU according to another embodiment of the present invention.

Referring to FIG. 4, a multi-wavelength optical transmitter of a multi-wavelength optical transceiver may include one or more fixed wavelength optical transmitters 430 and one or more wavelength tunable transmitters 440. The multi-wavelength optical receiver of the multi-wavelength optical transceiver may include one or more fixed wavelength optical receivers 460.

Referring to FIG. 4, the fixed wavelength optical receiver 480 may be coupled to the variable filter 470 to receive optical signals of a plurality of wavelengths. The tunable filter 470 may change the wavelength of the optical signal to the wavelength of the fixed wavelength optical receiver 480. The fixed wavelength optical receiver 480 can receive optical signals of different wavelengths by receiving optical signals whose wavelengths have been changed by the variable filter 470.

The fixed wavelength optical transmitter 430 and the fixed wavelength optical receiver 460 may be devices that are integrated using array technology. The tunable optical transmitter 440 and tunable filter 470 may utilize thermooptical effects, electrooptic effects, or mechanical optic effects.

4, optical signals output by the fixed wavelength optical transmitter 430 and the wavelength tunable optical transmitter 440 at the same time can be multiplexed by the multiplexer 420. The multiplexed optical signal can be output to the optical fiber by the wavelength division multiplexing unit 410. The ONU including the multi-wavelength optical transceiver can selectively activate the fixed wavelength optical transmitter 430 or the wavelength tunable optical transmitter 440 in accordance with the registration message.

Referring to FIG. 4, the ONU may include fixed wavelength optical transmitters 430 for each of wavelengths .lamda.U1 through .lamda.Ui. The wavelength tunable optical transmitter 440 can generate an optical signal using any one of the wavelengths? Uj to? Un. If the ONU has a wavelength designated by the OLT among wavelengths? U1 to? Ui, the ONU can activate the fixed wavelength optical transmitter 430 corresponding to the wavelength designated by the OLT. If the ONU has a wavelength designated by the OLT among the wavelengths? Uj to? Un, the ONU can change the wavelength of the wavelength variable optical transmitter 440 according to the wavelength designated by the OLT.

The wavelength division multiplexing unit 410 may output the optical signal received through the optical fiber to the demultiplexing unit 450. The demultiplexer 450 demultiplexes the optical signals and then distributes the demultiplexed optical signals to the plurality of fixed wavelength optical receivers 460 according to wavelengths. Referring to FIG. 4, the ONU may include fixed wavelength optical receivers 460 for wavelengths? D1 to? Di, respectively. The demultiplexer 450 can distribute the optical signals having the wavelengths? D1 to? Di to the fixed wavelength optical receiver 460 according to the wavelengths.

Referring to FIG. 4, the wavelength of the optical signal demultiplexed by the demultiplexer 450 may be wavelengths? Dj to? Dk in addition to wavelengths? D1 to? Di. The demultiplexer 450 can output the optical signals having the wavelengths? Dj to? Dk, which are not supported by the fixed wavelength optical receiver 460, to the variable filter 470. The variable filter 470 can change the optical signals of the wavelengths? Dj to? Dk, which are not supported by the fixed wavelength optical receiver 460, to the optical signals of the wavelength? Dk that can be received by the fixed wavelength optical receiver 480. The fixed wavelength optical receiver 480 can receive the optical signal of the changed wavelength? Dk.

5 is a flowchart illustrating an operation performed by an OLT according to an exemplary embodiment of the present invention.

Referring to FIG. 5, in step 510, the OLT according to an embodiment may transmit a discovery gate message including information on a wavelength used in a PON to which an OLT is connected, to an ONU. The discovery gate message may indicate the type of ONU that the OLT can support or the information of the wavelength channel that the OLT can support in the discovery information field. The discovery gate message may include information about the discovery window.

In the discovery window, the OLT can wait for the registration request message of the ONU without sending a message. Referring to FIG. 5, in step 520, the OLT according to an exemplary embodiment may receive a registration request message of an ONU. If the OLT receives the registration request message of the ONU, in step 530, the OLT according to one embodiment can identify the wavelength that the ONU can support from the registration request message. From the registration request message, the OLT can identify the type of optical transceiver included in the ONU or one or more wavelengths that the optical transceiver can output.

Referring to FIG. 5, in step 540, the OLT according to an exemplary embodiment may determine a target wavelength to be used when an ONU transmits and receives a message to / from the OLT, taking into consideration the wavelengths that the ONU can support and the wavelengths used in the PON . That is, the target wavelength can be determined from the wavelengths that the ONU can support and the wavelengths commonly included in the wavelengths used in the PON. The OLT can determine the target wavelength considering the type of ONU.

That is, the target wavelength can be determined for the ONU equipped with the wavelength tunable optical transceiver within the wavelength variable range of the wavelength variable optical transceiver that the ONU transmits to the OLT through the registration request message. The OLT can determine the target wavelength to be one of the wavelengths used in the PON and the wavelength included in the plurality of wavelengths that the ONU can support.

In the case of an ONU equipped with a multi-wavelength optical transceiver capable of transmitting and receiving an output wavelength to two or more wavelength channels, the target wavelength channel is selected from among wavelengths output from the far wavelength optical transceiver, which is transmitted to the OLT through the registration request message, The target wavelength may be determined to be one or two or more. In the case where the optical transceiver of the ONU is a multi-wavelength optical transceiver that transmits and receives a message using a plurality of wavelengths simultaneously among a plurality of wavelengths that the ONU can support, the OLT can transmit one or more target wavelengths, wavelengths used in the PON, Can be determined among wavelengths commonly included in a plurality of wavelengths.

As described above, the OLT can determine the target wavelength of the ONU in consideration of the wavelength capability of the ONU. That is, for different ONUs, the target wavelength may be determined differently for different wavelength output characteristics of the ONUs. Therefore, several kinds of ONUs having different wavelength output characteristics can coexist in the PON.

The OLT may broadcast a registration message in which the target wavelength is indicated, in order to deliver the determined target wavelength to the ONU. The OLT can display the target wavelength in the Assigned wavelength channel map field of the registration message.

Referring to FIG. 5, in step 550, an OLT according to an embodiment may transmit a gate message to an ONU to determine whether the optical transceiver of the ONU has activated the wavelength according to the target wavelength. The gate message may include an Assigned wavelength channel field.

The ONU can transmit a Registration Acknowledgment Message in response to the Gate message. The registration confirmation message may display the assigned wavelength channel field value of the gate message in the Echo of assigned wavelength channel field.

At step 560, if the OLT receives a registration confirmation message, at step 570, the optical transceiver of the ONU may determine whether it is activated according to the target wavelength. The OLT can compare the value of the assigned wavelength channel field of the gate message with the value of the echo-assigned wavelength channel field of the registration confirmation message. When the value of the assigned wavelength channel field differs from the value of the echo-assigned wavelength channel field of the registration confirmation message, the OLT can determine that the optical transceiver is not activated according to the target wavelength. If the optical transceiver is not activated according to the target wavelength, the OLT may return to step 510 and send a discovery message to the ONU.

If the value of the assigned wavelength channel field and the value of the echo-assigned wavelength channel field of the registration confirmation message are the same, the OLT can determine that the optical transceiver is activated according to the target wavelength. If it is determined that the optical transceiver is activated according to the target wavelength, the registration process of the OLT and the ONU can be completed. Thereafter, the OLT and the ONU can transmit and receive a message using the target wavelength.

After the registration process is completed, the OLT can assign a new wavelength channel as a target wavelength to the ONU based on the wavelength output characteristic information of the ONU (i.e., information on the wavelength channel supported by the ONU). That is, the target wavelength used by the ONU can be changed in the process of transmitting and receiving a message. The target wavelength may be changed to efficiently provide functions such as load balancing, power saving, or protection of the PON. The number of target wavelengths may be two or more depending on the wavelength output characteristics of the ONU.

6 is a flowchart illustrating an operation performed by an ONU according to an exemplary embodiment of the present invention. The ONU may include a fixed wavelength optical transceiver, a wavelength tunable optical transceiver, or a multiwavelength optical transceiver. The ONU can transmit the type of optical transceiver or the wavelength supported by the optical transceiver to the OLT. The OLT can determine one or more target wavelengths to be used by the ONU based on the type of optical transceiver of the ONU or the wavelength supported by the optical transceiver.

Referring to FIG. 6, in step 610, an ONU according to one embodiment may receive a discovery gate message from an OLT. Upon receiving the discovery gate message, in step 620, the ONU according to one embodiment can identify the type of ONU that the OLT can support based on the discovery gate message. Alternatively, the ONU can identify wavelengths that the OLT can support, based on the discovery gate message. Further, the ONU can identify a discovery window, which is a time period during which a registration request message can be transmitted, based on the discovery gate message. The discovery gate message may be generated according to the Multi-Point Control Protocol (MPCP).

Referring to FIG. 6, in step 630, an ONU according to an exemplary embodiment may transmit a registration request message to the OLT. The ONU can indicate the type of optical transceiver or the wavelength supported by the optical transceiver in the registration request message. The ONU can send a registration request message to the OLT after a certain delay time has elapsed since the discovery window was started. The registration request message may be generated according to the MPCP.

The OLT having received the registration request message can identify the type of the optical transceiver included in the ONU or the wavelength supported by the optical transceiver based on the registration request message. The OLT can determine the target wavelength to be used by the ONU, taking into consideration the type of optical transceiver of the ONU or the wavelength supported by the optical transceiver. The OLT can transmit a registration message to the ONU including the result of determining the target wavelength. The registration message may be generated according to the MPCP. The registration message may include an LLID or the like to be assigned to the ONU.

Referring to FIG. 6, in step 640, an ONU according to an exemplary embodiment may wait for an OLT registration message. Upon receiving the registration message of the OLT, in step 650, the ONU according to one embodiment may activate the optical transceiver according to the target wavelength indicated in the registration message. For example, if the optical transceiver includes a plurality of fixed wavelength optical transmitters, the ONU may selectively activate a fixed wavelength optical transmitter corresponding to the target wavelength. As another example, if the optical transceiver includes a wavelength tunable optical transmitter, the ONU can adjust the wavelength of the tunable optical transmitter such that the wavelength tunable optical transmitter generates an optical signal according to the target wavelength. The ONU can activate the optical transceiver according to the wavelength band and the number of the target wavelength.

Referring to FIG. 6, in step 660, an ONU according to one embodiment may wait for a gate message of the OLT. Upon receiving the Gate message transmitted by the OLT, in step 670, the ONU according to one embodiment may transmit a registration confirmation message to the OLT. The ONU may generate a registration confirmation message in response to the gate message. The generated registration confirmation message may include the result of the ONU activating the optical transceiver. That is, the registration confirmation message may include information on the wavelength used by the ONU.

Upon receiving the registration confirmation message, the OLT can identify the result of activating the optical transceiver from the ONU from the registration confirmation message. That is, the OLT can determine, based on the registration confirmation message, whether the ONU has activated the optical transceiver according to the target wavelength included in the registration message. If the ONU activates the optical transceiver according to the target wavelength included in the registration message, all registration methods of the ONU can be completed. Thereafter, the OLT and the ONU can transmit and receive a message using the target wavelength.

By performing the registration method according to one embodiment, the OLT and the ONU can register different optical transceivers or ONUs supporting different wavelengths as one OLT. That is, the OLT can support different ONUs at the same time. Furthermore, the OLT can set different wavelength bands or numbers of target wavelengths to be used by the ONUs according to the wavelength output characteristics of the ONUs. Therefore, the OLT and the ONU can use the wavelength band more efficiently.

The components described in the embodiments may be implemented by a programmable logic device such as one or more DSP (Digital Signal Processor), a processor, a controller, an application specific integrated circuit (ASIC), and a field programmable gate array Logic Element, other electronic devices, and combinations thereof. ≪ RTI ID = 0.0 > At least some of the functions or processes described in the embodiments may be implemented by software, and the software may be recorded in a recording medium. The components, functions and processes described in the embodiments may be implemented by a combination of hardware and software.

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

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

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

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

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

110: PON
120: OLT
130: Optical splitter
141, 142, 143: ONU

Claims (1)

A method of registering an optical network unit (ONU) performed by an optical line terminal (OLT)
Transmitting, to the optical network unit, a discovery gate message including wavelength information used in a passive optical network (PON) connected to the optical line terminal;
Identifying a wavelength that the optical network unit can support from a registration request message transmitted by the optical network unit corresponding to the discovery gate message; And
Determining a target wavelength to be used when the optical network unit transmits / receives a message to / from the optical line terminal, considering wavelengths that the optical network unit can support and wavelengths used in the passive optical network
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