KR100759821B1 - Wavelength division multiplexing passive optical networksWDM-PONs and method of initializing wavelength in the same WDM-PONs - Google Patents

Abstract

The present invention provides a wavelength division multiplexing passive optical subscriber network capable of automatically initializing a wavelength of a tunable light source when a tunable laser is used for ONT, and a wavelength initialization method of the optical subscriber network. The optical subscriber network (WDM-PONs) is a wavelength division multiplexing passive optical network (WDM-PONs), which is a WDM-PONs Master Control for wavelength initialization in the physical layer. An optical line terminal (OLT) including a WPMC; An optical network terminus (ONT) including a tunable laser diode (TLD) and an optical subscriber network sub-control unit (WPSC) for initializing wavelengths in a physical layer; And an outdoor node (RN) relaying the base station transmitter and subscriber stations, and may initialize wavelengths of the TLD by exchanging wavelength initialization information between the WPMC and the WPSC.

Description

Wavelength division multiplexing passive optical networks (WDM-PONs) and method of initializing wavelength in the same WDM-PONs}

1 is a structural diagram of a WDM-PON including a WPMC and a WPSC according to an embodiment of the present invention.

2A to 2B are graphs showing wavelength tuning characteristics and sampling values according to wavelength control values.

3A to 3B are flowcharts illustrating a table configuration algorithm and an optimal value determination algorithm according to an embodiment of the present invention.

4 is a state flowchart illustrating a wavelength initialization function in a WPSC according to an embodiment of the present invention.

5 is a state flowchart showing a wavelength initialization function in a WPMC according to an embodiment of the present invention.

6 is a schematic diagram illustrating a message transmission process between a WPMC of an OLT and a WPSC of an ONT according to an embodiment of the present invention.

7A to 7B are frame structure diagrams of a WPCP for wavelength initialization of a WDM-PON according to an embodiment of the present invention.

<Description of main parts in the drawing>

100: OLT Physical Layer 101: OLT Transceiver

102: power monitoring unit

103,104,143,144: Interface

106: optical subscriber network main control unit (WPMC) 110,130: optical multiplexer and demultiplexer

120: optical fiber 140: OLT physical layer

141: transceiver of the ONT 142: wavelength control unit (WCE)

146: WPSC 210: Idle code (/ I /) area

220: structure alignment set (/ C /) area 230: information area

232: WID area 234: Frame type (FT) area

236: sub information area

The present invention relates to Wavelength Division Multiplexing Passive Optical networks (WDM-PONs), and particularly when a variable light source is mounted at an optical network terminal (ONT), automatically without user intervention. The present invention relates to a wavelength division multiplexing passive optical subscriber network capable of aligning or initializing the same, and a wavelength initialization method of the optical subscriber network.

Recently, Fiber To The Home (FTTH) technology, which connects fiber optics from the telephone company to the home, is being actively researched and developed around the world to provide voice, data, and broadcasting convergence services to subscribers.

The key to the development of the FTTH technology is the development of an optical signal transmission method that has to be economical due to the characteristics of the subscriber network and has excellent mass productivity. Optical subscriber network is largely divided into PON (Passive Optical Network) and AON (Active Optical Network). The PON method is being developed in various forms such as ATM-PON, B-PON, G-PON, and E-PON, and the AON method is being developed to connect a local network composed of Ethernet switches to an optical fiber.

WDM-based FTTH, that is, WDM-PONs can provide independent and large capacity communication service for each subscriber in such a way that communication between central base station and subscriber uses communication with each wavelength specified for each subscriber and excellent security. In addition, since the modulation and demodulation of the light source is performed only for one subscriber, it is possible to use a light source with a low modulation rate and a low bandwidth and a receiver with low bandwidth, which is different from the time division multiplexing (TDM) method.

However, in order to configure WDM-PONs, as many light sources as the number of subscribers belonging to one outdoor node (Remote Node: RN) are required. The production, installation, and management of these light sources by wavelengths are a great economic burden for both users and operators, which is a major obstacle to the commercialization of WDM-PONs. To overcome this problem, Planar Lightwave Circuit-External Cavity Laser (PLC-ECL) can be manufactured at low cost, and WDM-PONs can be controlled by electrical control signals from one light source of the same type. It has the characteristic to oscillate all wavelengths required for.

The wavelength assigned to the subscriber's ONT is determined by the pass wavelength of the connected aligned waveguide grating (AWG). Thus, the WDM-PONs system must support a set of initialization functions to align the wavelengths of the ONT's network connections. The initialization method of the wavelength tunable ONT light source may be classified into an optical layer initialization method and a frame layer initialization method proposed by the present invention according to an implementation form.

The initialization method in the optical layer is a method of determining the wavelength in the optical layer based on an optical signal transmitted from an optical line terminal (OLT). In this case, the OLT provides a seed light source for ONT light source locking or reflection, such as a Broadband Light Sourse (BLS). ONT provides an assigned wavelength using a locking or reflecting mechanism based on the seed light source received from the OLT. However, this approach has the limitation that the OLT must provide an additional seed light source and the ONT must accept a locked or reflective mechanism.

However, the above-described low-cost PLC-based tunable laser (PLC-ECL) does not use such a locking or reflection mechanism and uses an independent electric control signal, and thus it is difficult to apply the optical layer initialization method. Therefore, when a wavelength tunable laser such as PLC-ECL is separately used for ONT, an alignment method or an initialization method for the tunable light source must be newly provided.

Accordingly, a technical problem to be achieved by the present invention is to provide a wavelength division multiplexing passive optical subscriber network and a wavelength initialization method for the optical subscriber network that can automatically initialize the wavelength of the variable wavelength light source when the variable wavelength laser is used for ONT. To provide.

In order to achieve the above technical problem, the present invention, in the Wavelength Division Multiplexing Passive Optical Networks (WDM-PONs), the optical subscriber network main control unit for wavelength initialization in the physical layer (Physical layer) An optical line terminal (OLT) including a WDM-PONs Master Control (WPMC); An optical network terminus (ONT) including a tunable laser diode (TLD) and an optical subscriber network sub-control unit (WPSC) for initializing wavelengths in a physical layer; And a remote node (RN) for relaying the base station transmitting end and the subscriber end, the wavelength division multiplexing passive optical subscriber network capable of initializing the wavelength of the TLD by exchanging wavelength initialization information between the WPMC and the WPSC. To provide.

In the present invention, the WPSC varies the wavelength of the TLD while changing a Wavelength Control Index (WCI), and the WPMC receives the power of an optical signal corresponding to each of the WCI and the WCI, thereby providing an optimal WCI. Determine a value, and the WPSC may receive the optimal WCI value to initialize the wavelength of the TLD. Meanwhile, the wavelength initialization information may include the WCI, power of an optical signal, and an optimal WCI.

In the present invention, the OLT includes a power monitoring entity (PME) for observing the optical power of the received optical signal and transmitting to the WPMC, the ONT is the optimal WCI delivered to the WPSC from the WPMC It may include a wavelength control unit (Wavelength Control Entity (WCE)) for receiving and converting the wavelength control signal to the WPSC.

In the present invention, the WPMC may use an optimal value algorithm to determine the optimal WCI value, the optimal value algorithm comprising: a table construction algorithm for preparing values of parameters including the WCI and measured optical power; And an optimum value determination algorithm for determining an optimum control value using the values created through the table configuration algorithm.

The parameters of the table configuration algorithm may include: a monitoring power (MP) corresponding to each of the WCI, the WCI, a number corresponding to each of the WCIs (Number: N), and a partition number to which the WCI belongs; PN), and the partition length (PL), wherein the determination parameters of the optimum value determination algorithm include an optimal control value (I _opt ), an optimal length (OL), an optimal partition (OP), and a number (N). ) And optimal number (ON).

In the present invention, the ONT receives an Advertising (AD) message from the WPMC by using the first time clocks after the WPSC is powered on or reset of the WPSC of the ONT, and receives the WCI. The initial value may be set, and an optical signal having a wavelength corresponding thereto may be transmitted to the WPMC while the WCI is changed, and an optimal WCI may be received from the OLT to perform a wavelength initialization function.

An inter-frame guard time (IFGT) corresponding to an interval between periodic transmissions of the changed optical signal in the step of transmitting the first time clocks to the WPMC; An optical stabilization guard time (OSGT) corresponding to the time required for the optical stabilization time of the changed optical signal; A clock lock time (CLT) corresponding to a time for restoring a clock of the received optical signal in the OLT; And a stabilization and clock lock guard time (SCGT) corresponding to the change of the WCI and the sum of the optical signal clock recovery time.

In the present invention, the OLT, after the WPMC is powered on or reset, the WPMC transmits an AD message to the WPSC using second time clocks, and receives an optical signal including the WCI from the WPSC. And an optimal value algorithm including a table configuration algorithm for preparing values of parameters including the WCI and measured optical power, and an optimal value determination algorithm for determining an optimal control value using the values generated through the table configuration algorithm. Determine an optimal WCI, and transmit the optimal WCI to the WPSC to perform a wavelength initialization function.

The second time clocks may include a search loop time (SLT) corresponding to a time required for monitoring the reception power for the entire variable band; Acknowledgment Time (ACKT) corresponding to the time to wait to receive an acknowledgment (ACK) message including the optimal WCI from the WPSC after determining an optimal WCI; And a Message Interval Time (MIT) corresponding to a transmission interval of the AD message.

In the present invention, the frame structure of the WDM-PONs Control Protocol (WPC-PONs Control Protocol (WPCP)) for the wavelength initialization of the optical subscriber network is an idle code (Idle Code: / C /) region, configuration ordered set (Configuration Ordered) Set: / C /) area and Information area, and the structure alignment set area may be used to perform the wavelength initialization function.

The WPMC may extract a frame encapsulated into the structure alignment set from the binary code received from the optical transceiver, or may encapsulate and insert the frame into the structure alignment set. Meanwhile, the information area may have a wavelength identification (WID) area, a frame type (FT) area indicating a message type, and may have different shapes according to the FT, and may store sub information (Sub) for storing specific values of fields. -information) region, and the FT may include four frame types defined in the WPSC direction in the WPMC and two frame types defined in the WPSC in the WPMC.

The four frame types include a SET type for setting the wavelength control value of the ONT, a GET type for reporting the current wavelength control value to the WPMC, and a control range and control between remote nodes. An AD type for setting a width to the WPSC, and a STOP type for causing the ONT to stop the wavelength initialization function and maintain the current control value to maintain the link state, the two frames The type is a report type for reporting the WCI on the currently transmitted optical signal to the WPMC and a recognition for reporting a control value to the WPMC after controlling a wavelength when receiving a set command from the WPMC. ACK) type.

In another aspect, the present invention, in order to achieve the above technical problem, in the optical signal transmission method of the WDM-PONs, the wavelength of the TLD of the WDM-PONs including a Tunable Laser Diode (TLD) in the ONT Provided is a wavelength initialization method of a wavelength division multiplexing passive optical subscriber network.

In the present invention, the wavelength initialization method comprises: a table construction algorithm for preparing values of parameters including the WCI and measured optical power; And an optimal value determination algorithm for determining an optimal control value using the values created through the table configuration algorithm.

The parameters of the table configuration algorithm may include: a monitoring power (MP) corresponding to each of the WCI, the WCI, a number corresponding to each of the WCIs (Number: N), and a partition number to which the WCI belongs; PN), and a Partition Length (PL), wherein the table configuration algorithm comprises: setting an initial value to the parameters; The OLT receiving an optical signal including the WCI from the ONT; Comparing the MP of the optical signal with a sum of a System Power Margin (SPM) and a Receiver Sensitivity (RS) of the receiver; Increasing the 1 to N when the MP is greater than or equal to the SPM + RS and comparing the WCI with the sum of the Before WCI (BWCI) and the control width (Δ) of the WCI; And writing the parameter to the table according to the comparison result.

In the step of creating the table, if the WCI is equal to BWCI + Δ in the comparing step, the value is increased to 1 in the PL, and the WCI, MP, N, PN, and PL are written in the table, and the WCI is used in the comparing step. Is not equal to BWCI + Δ, the value is increased to 1 in the PN, the PL value is written in the partition length description parts corresponding to PN-1 in the table, the value is stored in PL, and then the WCI, MP, N, PN and PL can be written in the table.

In the step of comparing the MP and SPM + RS, if the MP is smaller than the SPM + RS, the process returns to the step of receiving the optical signal, and the process returns to the step of receiving the optical signal even after the table creation step. The algorithm may be terminated when a Search Loop Time_out (SLT_out) signal or an algorithm termination signal is received at. Meanwhile, the initial values of the parameters may be set to 0 for BWCI, N, and PL, and 1 for PN.

The optimal value determination algorithm includes an optimal control value (I _opt ), an optimal length (OL), an optimal partition (OP), a number (N), and an optimal number (ON) as decision parameters, and an initial value in the decision parameters. A setting step of setting; A comparison step of reading the WCI, MP, PN and PL data written in the table and comparing the OL with the PL; Changing the values of the determination parameters in accordance with the comparison result; A checking step of checking whether the table is at the end; And an input step of inputting a WCI value corresponding to the ON to the I _opt when the table is at the end of the table.

The comparing step includes a first comparing step of comparing the OL and the PL; A second comparing step of determining whether the OL is equal to the PL when the OL is less than or equal to the PL; And a third comparison step of comparing the OP and the PN in the same case. If the OP and the PN are different in the third comparison step, the process enters a change step. Increases, skips the change step and enters the check step, and immediately enters the change step in another case in the second compare step, and if the OL is greater than the PL in the first compare step, Increases 1 and skips the change step and enters the check step, where N + [PN / 2] for ON, PL for OL, N + PL for N, and PN for OP Each can be stored. Where [] represents the mathematical symbol of truncation.

On the other hand, if it is not the end of the table in the inspection step may enter the comparison step. In addition, the initial values of the determination parameters may be set to I _opt , OL and OP and 0 and N and ON to 1.

The method of claim 1, wherein the ONT is further configured to receive an advertising (AD) message from the WPMC by using the first time clocks after the WPSC is powered on or reset; Setting the WCI to an initial value; Transmitting an optical signal having a wavelength corresponding to the WCI to the WPMC while changing the WCI; And receiving an optimal WCI from the OLT.

The transmitting of the WPMC may periodically transmit an optical signal having a wavelength corresponding to the WCI to the WPMC before proceeding to the optimal WCI receiving step.

An inter-frame guard time (IFGT) corresponding to an interval between periodic transmissions of an optical signal having a wavelength corresponding to the WCI in the step of transmitting the first time clocks to the WPMC; An optical stabilization guard time (OSGT) corresponding to the time required for the optical stabilization time of the changed optical signal; A clock lock time (CLT) corresponding to a time for restoring a clock of the received optical signal in the OLT; And a stabilization and clock lock guard time (SCGT) corresponding to the change of the WCI and the sum of the optical signal clock recovery time.

The change in the WCI increases with a predetermined interval between the set minimum value and the maximum value, and may stop when the optimal WCI is received. When the WPSC receives the optimal WCI value, the WPSC transmits an acknowledgment (ACK) message including the optimal WCI value to the WPMC, terminates the wavelength initialization function, and then uses the optical power corresponding to the optimal WCI. If the signal transmission is performed but an error occurs in the optical signal transmission, it may proceed to the AD message receiving step of the wavelength initialization function again.

In the present invention, the OLT comprises the steps of: after the WPMC is powered on or reset, the WPMC transmits an AD message to the WPSC using second time clocks; Receiving an optical signal including the WCI from the WPSC; Optimal using an optimal value algorithm including a table configuration algorithm for preparing values of parameters including the WCI and measured optical power and an optimal value determination algorithm for determining an optimal control value using the values created through the table configuration algorithm. Determining a WCI; Transmitting the optimal WCI to the WPSC; and may perform a wavelength initialization function.

In the AD message transmitting step, before the WCI receiving step proceeds, the AD message is periodically transmitted to the WPSC, and the AD message includes Wavelength Identification (WID) assigned to each port, minimum and maximum values of WCI, and It may include information on the constant control width Δ between the WCI values.

The second time clocks may include: a search loop time (SLT) corresponding to a time required for monitoring reception power for the entire variable band; Acknowledgment Time (ACKT) corresponding to the time to wait to receive an acknowledgment (ACK) message including the optimal WCI from the WPSC after determining an optimal WCI; And a Message Interval Time (MIT) corresponding to a transmission interval of the AD message.

After determining the optimal WCI, if the WPMC receives the acknowledgment (ACK) message including the optimal WCI during the ACKT time, the wavelength initialization function is terminated and the optical signal having the optical power corresponding to the optimal WCI is transmitted. Although the function is performed, if an error occurs in the reception of the optical signal, the process proceeds to the step of transmitting the AD message of the initial wavelength and the function again. If the acknowledgment (ACK) message is not received, the process may be performed.

The WDM-PONs of the present invention include WPMC and WPSC as physical layers, and can automatically arrange or initialize wavelengths of the tunable light sources included in the ONT to their own wavelengths without user intervention. This can significantly increase the availability of the network and also significantly reduce the costs associated with the use of conventional variable wavelength remote monitoring or control devices.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention; In the following drawings, each component is exaggerated or schematically represented for convenience and clarity of description, and parts irrelevant to the description are omitted. Like numbers refer to like elements in the figures. On the other hand, the terms used are used only for the purpose of illustrating the present invention and are not used to limit the scope of the invention described in the meaning or claims.

1 is a structural diagram of a WDM-PONs including a WDM-PONs Master Control (WPMC) and a WDM-PONs Slave Controller (WPSC) according to an embodiment of the present invention. It shows the structure of the WDM-PON link where the physical layers of the WDM-PONs are connected point-to-point.

Referring to FIG. 1, WDM-PONs basically include a base station transmitting end (OLT), an outdoor node (Remote Node: RN), and a subscriber end (ONT). The WDM-PONs of the present invention include a Tunable Laser Diode (TLD) with ONT, and the physical layers (100,140) of the OLT and ONT of the WDM-PONs are the physical coding sublayers of 1000Base-X optical fibers. It may be configured similarly to the physical layer of Ethernet including Sublayer (PCS), Physical Media Attachment (PMA), and Physical Medium Dependent (PMD).

In the present invention, for the sake of simplicity, a transmission function defined in IEEE 802.3, which is a standard protocol for a medium access control (MAC) layer and a physical layer defined by the Institute of Electrical and Electronic Engineers (IEEE) Includes PCS and Serialization and Deserialization (Serdes), Clock Recovery and Code Synchronization, including Receive, Synchronization, and 8B / 10B Encoding / Decoding. PMA function is omitted.

The physical layer 100 of the OLT includes an optical subscriber network main controller 106 (WDM-PONs Master Control (WPMC)) and a transceiver (101, Transceiver: TR). The transceiver 101 is connected to the optical multiplexing and demultiplexing unit 110. Each WPMC 106 and the transceiver 101 are distinguished according to the wavelength, so '-Wn' is added for convenience. The WPMC 106 can extract a 32-bit frame that is encapsulated from a binary code received from the transceiver 101 into a configuration ordered set (/ C /) defined in IEEE 802.3. In addition, the frame may be encapsulated in / C / and transmitted to the optical subscriber network sub-control unit 141 (WDM-PONs Slave Control: WPSC) of the corresponding ONT through the interface 103.

Meanwhile, the transceiver 102 includes a power monitoring entity (PME) for observing the optical power of the received optical signal. The PME 102 transmits the received optical power through the interface 104 to the WPMC ( Report). Here, the PME 102 may include a power detector and a digital / analog converter for converting the input optical signal strength into analog values.

OLT's single-mode light sources (not shown) send out unique N wavelengths for each of the N ONTs in each downlink signal, and the transceiver 102 array is connected to a pin-photodiode (PIN-PD) or Avalanche Photodiodes (APD) may be configured to receive uplink signals λ _j and j = 1 to N of different wavelengths from ONT. The optical multiplexing and demultiplexing unit 110 in the OLT multiplexes the outputs of the N single mode light sources, and transmits the downlink signal to the optical fiber 120, and the optical multiplexing and demultiplexing unit 130 of the RN is inputted downward. Demultiplex the signal and pass it to the corresponding ONT. Meanwhile, the optical multiplexing and demultiplexing units 110 and 130 of the OLT and RN perform a reverse function with respect to an uplink signal oscillating from the ONT.

The physical layer 140 of the ONT includes the WPSC 146 and the transceivers 141 and TR. Also, '-Wn' is added to distinguish the wavelength. The WPSC 146 may extract or encapsulate a frame from the binary code input from the transceiver 141 in the same manner as the WPMC 106 described above. When encapsulating the frame, the WPSC 146 may use the interface 143. The frame can be delivered to the WPMC 106 by delivering it to the optical module. The WPSC 146 converts a wavelength control index (WCI) from the WPMC 106 into a wavelength control signal, such as a heat current, a phase section current, a thermoelectric cooler. Wavelength control unit 142 (WCE) for converting into a control signal, such as TEC), the wavelength control signal converted in the WCE 142 may be transmitted to the WPSC 146 through the 144 interface 144 have. The WCE 142 may include a thermal current controller, a phase domain current controller, a TEC, and the like for converting the digital value WCI into an analog signal.

2A to 2B are graphs showing wavelength tuning characteristics and sampling values according to a wavelength control value WCI of a general wavelength variable light source TLD.

FIG. 2A is a graph showing wavelength tuning characteristics of a WLD of a TLD mounted on an Nth ONT (ONTn), where WCI is a physical value varying the wavelength of the TLD, such as thermal current (mA) and phase-domain current (mA). , TEC temperature) and the like and can be used according to the wavelength tuning characteristics thereof. Here, B shows an ideal wavelength tuning curve, C shows an ONTn wavelength tuning curve, and D shows a power transfer function curve of an arrayed waveguide grating (AWG). Here, CP shows a channel spacing interval. In the graph, the vertical axis represents wavelength and the horizontal axis represents WCI.

As can be seen from the graph, it is very difficult to realistically map the relationship between the WCI and the oscillating wavelength to an ideal shape such as B. Further, when WCI is i, if the wavelength of the light source k is W _{i , k} , it is impossible to keep W _{i , k} constant for all i. However, since the present invention is designed to overcome the above two limitations and to perform wavelength initialization through automatic wavelength alignment, the wavelength characteristic curve of ONT applicable to the present invention does not need to be the same as ONTn.

On the other hand, the wavelength-variable light source generally exhibits a mode hopping phenomenon due to mode spacing. A region represents a mode hopping region. In the region A where such mode hopping occurs, the side mode suppression ratio (SMSR) of the oscillation wavelength is very low (about -20 dB or less), and thus an area where communication is not possible appears. For this reason, the WCI observed in the WPSC 146 of the ONT does not appear at regular intervals Δi.

2B is a graph showing the oscillation wavelength transmitted from the ONTn filtered in the AWG, and shows the reception power P _rcv input to the ONTn through the AWG corresponding to the WCI.

Referring to the graph, the E region corresponding to the mode hopping region is an incommunicable region, and the other F and F1 regions are communicable regions. On the other hand, in view of OLT, even in a communicable area, a finally receivable area and a corresponding WCI are determined depending on the transceiver sensitivity (RS) and the system power margin (SPM) of the transceiver. . The dotted line RS [OLT] represents the reception sensitivity of the OLT, and the SPM [3dB] of the straight line represents the system power margin with a margin of 3dB. Accordingly, the final communicable area is an area where mode hopping does not occur among areas satisfying the RS and SPM of the OLT and appears discontinuously with respect to the WCI.

Figure 2c is a graph showing the appearance of the oscillation wavelength of the light source having the mode hopping characteristics to the WCI via the AWG.

Referring to the graph, the vertical axis represents the monitoring power (MP) of the OLT. In consideration of the RS and SPM of the OLT as described above, the WCI is increased (or decreased) at a predetermined interval (Δi) while communicating with the monitored power. The possible WCI is shown. As can be seen from the graph, since the WCI cannot be reported to the WPSC in the region filtered by the AWG and the communication impossible region, the WCI is not mapped to the MP, and thus the sampling value can be observed only in the communicable region.

Among the observed sampling values, the optimum control value I _opt for uplink communication satisfies the following three conditions in consideration of the SPM and system aging.

Condition 1: Should be 3 dB higher than RS.

Condition 2: It satisfies condition 1 and belongs to the longest area among the communicable areas.

Condition 3: Satisfy condition 1 and 2 and correspond to the center value of communication area.

In the above conditions, condition 1 considers the SPM, and conditions 2 and 3 consider the stable and continuous aspects of communication. In the case of the graph of FIG. 2C, since the G region is narrower than the H region, the H region satisfies condition 2, and the WCI centered on the H region should be selected as an optimal control value I _opt . Hereinafter, an algorithm for determining an optimal control value will be described with reference to FIGS. 3A to 3B.

3A to 3C are flowcharts illustrating a table configuration algorithm and an optimal value determination algorithm for determining an optimal control value according to an embodiment of the present invention.

3A is a flow chart showing a table construction algorithm for writing each parameter into a table to determine an optimal control value. To simplify the explanation of the algorithm, Write data (), Write date_length (), and Clear () are used to create a table, namely WCI & MP Mapping Table (WMMT). Write data () writes the values corresponding to the variables in parentheses to the table, and Write date_length () writes the partition length in the Partition Length (PL) area. Clear () initializes the WMMT.

As the main variable, Receive Number which shows WCI and Received Power that are observed in response to each WCI and WCI reported through the frame, and the arrival number of the frame in WPSC. Or a number (Number: N), a partition number (PN) to which the WCI belongs, and a partition length (PL), and a constant Δi representing a control width and a system power margin. Use SPM.

Referring to FIG. 3A, the functions of the table configuration algorithm will be described. First, variables are initialized (S100). As an initialization value, Before WCI (BWCI), N, and PL are set to 0, and the PN is set to 1. After initializing the variables, wait for WCI and MP in the WPMC (S110). When the WCI and the MP through the PME are received through the report message of the WDM-PONs Control Protocol (WPCP) (S200), the MP is compared with the SPM + RS (S120). The comparison of MP and SPM + RS reflects condition 1 above.

If MP is less than SPM + RS, wait for the next WCI (S110), if MP is greater than or equal to SPM + RS, increase 1 to N (S130), and compare WCI with BWCI + Δi (S140).

If WCI and BWCI + Δi are the same, 1 is increased to PL (S150), and write data () is called to write values stored in N, PN, WCI, MP, and PL to WMMT (S170). If WCI and BWCI + Δi are different, the PL values of the same partition area are rewritten as the last PL value of the same partition (S160), and the write data () is called to store the N, PN, WCI, MP, and PL stored in the WMMT. Create a value (S170).

The last PL value description part algorithm first increases 1 to PN (S152), and rewrites the PL values of the same partition area as the last PL value through a for loop (S154). Thereafter, 1 is stored in the PL (S156). This last PL value description part algorithm is executed when the WCI of another partition area is input, that is, when the mode hopping area appears and the next WCI value is larger than BWCI + Δi. On the other hand, the last PL value corresponds to the number of WCIs in the same partition area, and finally the last PL value description part algorithm reflects condition 2.

When the writing of one variable value is completed, the next WCI value is waited again (S110), and the WMMT is continuously created. Meanwhile, when the Search Loop Timeout (SLT_out) signal defined in the WPCP is received or the algorithm termination signal is input, the table configuration algorithm is terminated.

FIG. 3B is a table showing WMMTs created with the table corresponding to the graph shown in FIG. 2C, and shows a table before Clear () is executed. The PN values of the WCIs corresponding to the G region are 1, and the PN value corresponding to the H region is 2. In addition, the number of WCI belonging to each partition area is represented by PL value.

FIG. 3C illustrates an optimal value determination algorithm for determining an optimal control value based on the WMMT of FIG. 3B.

Determination parameters include an optimal control value (I _opt ), an optimal length (OL), an optimal partition (OP), a number (N :), and an optimal number (ON). The values are set to 0 for I _opt , OL and OP and 1 for N and ON. Meanwhile, () Read () and Read_data () are defined and used. () Read () reads the data values of the variables in the preceding parentheses corresponding to the numbers in the parentheses, and Read_data () reads the variable values in the parentheses. Read and return the corresponding WCI value.

Referring to FIG. 3C, the function of the optimum value determination algorithm will be described. First, initial values are set for each variable (S300). Next, data is read from the WMMT (S310), and OL is compared with the PL (S320). If OL is greater than PL, increase 1 to N (S370). If OL is less than or equal to PL, it is again compared whether OL is equal to PL (S330).

If OL is not equal to PL, N + [PL / 2] is set to ON, PL is set to OL, N + PL is set to N, and PN is set to OP (S350). Here, the symbol of [] is a mathematical symbol indicating rounding off or a maximum integer. On the other hand, if OL is equal to PL again OP and PN is compared (S340).

If OP and PN are not the same, N + [PL / 2] is turned ON again, PL is substituted for OL, N + PL is substituted for N, and PN is substituted for OP (S350). If OP and PN are the same, 1 is increased to N (S370).

After the substitution step S350 or the N increment step S370, it is determined whether there is the next data, that is, the end of the table END_of_DB (S360). If it is not the end of the table to continue reading the next data (S310), the algorithm proceeds. If it is the end of the table, the WCI value corresponding to ON is returned and stored in I _opt (S380), and the algorithm ends.

Through the above optimal value determination algorithm, it can be seen that the optimal control value of the WCI is determined to be 12377, which is the center value of the H region. On the other hand, the optimum value determination algorithm reflects condition 3.

The present invention includes the WPMC in the OLT and the WPSC in the ONT in order to transmit the unique wavelengths assigned to the ONT in the WDM-PONs including the wavelength variable light source with the ONT, and the aforementioned table configuration algorithm and the optimum value determination algorithm. By using, it is possible to determine I _opt , which is an optimal control value for the wavelength of the wavelength variable light source of the ONT.

4 is a state flowchart illustrating a wavelength initialization function in a WPSC according to an embodiment of the present invention.

The WPSC defines four times to perform the wavelength initialization function. First, Inter-Frame Guard Time (IFGT) means the interval between WPSC transmission messages. The smaller IFGT can reduce the time required for wavelength alignment, but the message overflow due to the delay of OLT message processing. It can cause an overflow. IFGT starts after transmitting a message in the initial state (S410, Init), the timeout (IFGT_out) signal means the start of the process for the next message transmission.

Optical Stabilization Guard Time (OSGT) refers to the time required for optical stabilization according to the change of ONT wavelength control value, and Clock Lock Time (CLT) is required to restore the received clock in OLT. It means time. Therefore, the stabilization and clock_lock guard time (SCGT) plus two protection times means a time interval from when the control value is changed to when the message is inserted. The SCGT starts in a tuning state (S420, Tuning) for converting the wavelength control value, and the timeout (SCGT_out) signal indicates the start of message transmission.

Referring to FIG. 4, the wavelength initialization function in the WPSC is described. When a system initialization is required, the WPSC secures control synchronization with the WPMC after a power-on or reset signal is first applied to the WPSC. In order to enter the start weight state (S400, Start_Wait). In the starting weight state (S400), the WPSC transitions to the initial state (S410, Init) upon receiving an advertising (AD) message from the WPMC. In the initial state (S410), the WPSC sets the WCI to the initial control value (i _o ), enters the transmission state (S420, Sending) by the SCGT_out signal, and sends a report message including the control value (i) information. Send to OLT. Here, the initial control value i _o is a value between the control minimum value i _min and the control maximum value i _max .

증가시키고 SCGT를 초기화하고, SCGT_out 신호에 따라 제어값(i) 정보를 포함하는 리포트 메시지를 OLT로 전송하는 전송상태(S420)로 재진입하고, WPMC로부터 AWG 파장과 일치하는 광신호를 생성하는 제어값, 즉 최적 제어값(I_opt)을 포함하는 셋(SET) 메시지를 수신할때까지 반복하여 상기 과정을 실시한다. 최적 제어값(I_opt)을 수신하면 WPSC는 인식상태(S450,Ack)상태를 거쳐 정상적인 통신진행상태(S460,Running)에서 데이터 송/수신 서비스를 시작한다. 인식상태(S450)에서는 수신한 최적 제어값(I_opt)을 포함한 인식(ACK) 메시지를 OLT로 송신한다.Upon entering the standby state (S440, Wait), the IFGT is initialized. When the IFGT_out signal is generated, the state transitions to the tuning state (S420, Tuning). In tuning state S420, the control value is adjusted by the control width Δi.

A control value for increasing and initializing the SCGT, re-entering the report message including the control value (i) information according to the SCGT_out signal to the transmission state (S420) for transmitting to the OLT, and generating an optical signal matching the AWG wavelength from the WPMC. That is, the process is repeated until the SET message including the optimal control value I _opt is received. Upon receiving the optimum control value I _opt , the WPSC starts the data transmission / reception service in the normal communication progress state (S460, Running) through the recognition state (S450, Ack) state. In the recognition state S450, an acknowledgment (ACK) message including the received optimal control value I _opt is transmitted to the OLT.

On the other hand, if the control value (i) in the tuning state (S420) exceeds the control maximum value (i _max ), and initializes again to the initial control value (i _o ), if an error occurs in the communication progress state (S460), Return to the initial start weight state (S400) and perform the initialization function again.

5 is a state flowchart showing a wavelength initialization function in a WPMC according to an embodiment of the present invention.

The WPMC defines three times to perform the wavelength initialization function. First, the search loop time (SLT) refers to the time required for monitoring the reception power of the entire variable band. SLT starts after receiving the first report message from the ONT in the OLT and is used as a trigger signal to enter the monitoring state (S510). The acknowledgment time (ACKnowledge Timer: ACKT) starts after determining the optimum control value (I _opt ) and transmitting a SET message containing the optimum control value (I _opt ) to the ONT. Used as a trigger signal. The Message Interval Time (MIT) represents the transmission interval of the advertisement (AD) message.

Referring to FIG. 5, the wavelength initialization function in the WPMC is described. The WPMC enters an initial state S500 and Init by a power-on or reset signal. In the initial state (S510), the WPMC initializes the SLT and periodically transmits an AD message to the WPSC according to the MIT. The advertisement message includes information about a wavelength identification (WID) assigned to each port, a control maximum (MAX) and a minimum (MIN), and a control width (STEP) for controlling the variable light source.

When the WPMC receives the REPORT message including the WCI from the WPSC, the WPMC transitions to the monitoring state (S510). In the monitoring state (S510), the received message from the WPSC is monitored, transitions to the searching state (S520, Searching) according to the SLT_out signal, and in the searching state (S520), the optimum control value using the optimal value determination algorithm presented above. Determine (I _opt ). When the next optimal control value (I _opt ) is determined, a transition to the setting state (S530, Setting) is performed, and a SET message including the optimal control value (I _opt ) is transmitted to the WPSC.

After initializing the ACKT in the setting state (S530) and receiving an acknowledgment (ACK) message including the optimal control value (I _opt ) from the WPSC before the ACKT_out signal, the communication proceeds to the communication progress state (S540, Running) and the data transmission / reception service Proceed with normal communication. If the ACKT_out signal is generated in the setting state (S530) or a communication error occurs in the communication progress state (S540), it returns to the initial state (S500) and performs the initialization function again.

6 is a schematic diagram illustrating a message transmission process between a WPMC of an OLT and a WPSC of an ONT according to an embodiment of the present invention.

Referring to FIG. 6, a message transmission process between the time bases of WPMC and WPSC and both time bases is shown on both sides. When the initialization function is started, the WPMC is initially configured with AD (AD), which consists of WID assigned to each port, MAX, MIN and STEP for control of the variable light source. Send a message to WPSC in MIT cycle. The highest and lowest values include the ONT-specific motion prediction range, and the wavelength search within the motion prediction range is expected to effectively reduce the wavelength initialization delay time.

After powering on, ONT's WPSC waits for an AD message from the OLT in standby. The WPSC receives the advertisement message, waits for the SCGT, automatically aligns the wavelengths based on the control range and control width included in the advertisement message, and sends the control value (WCI) to the OLT via a REPORT message. . At this time, ONT automatically calculates the next control value and continuously sends a report message to the OLT.

After receiving the first report message, the WPMC stops sending AD messages and initializes the SLT. During the SLT, the OLT creates a table using the table composition algorithm through the report message and the received optical power observed by the optical power monitor (PME), and determines the optimal control value from the optimal value determination algorithm after the SLT_out signal. The control value is transferred to the ONT via the SET message.

ONT fixes the wavelength according to the optimum value obtained from the SET message, and finishes the initialization process of wavelength automatic alignment by notifying the OLT in ACKT_out through an acknowledgment (ACK) message containing the optimal control value.

7A to 7B are frame structure diagrams of a WPCP for wavelength initialization of a WDM-PON according to an embodiment of the present invention.

Referring to FIG. 7A, the WPCP frame includes an idle code (/ I /) area 210, a structure alignment set (/ C /) area 220, and an information area 230. The frame is in / I / region 210 and the OLT's Optical Transmitter Stabilization Time (OTST), ONT's Optical Receiver Stabilization Time (ORST), and Receiv Clock Lock Time: RCLT), and includes the / C / region 220 as a discriminator to distinguish the frames in the PCS layer transmission and reception function. The configuration method of / C / follows the PCS layer standard of 1000Base-X of IEEE802.3 as described above.

All codes transmit / I / of IEEE802.3 from the start of transmission until insertion of / C /, and / I / is used for reproducing the receive clock of the receiver and synchronizing codes.

FIG. 7B shows the information area 730 of FIG. 7A in detail. The WID region 232 represents a wavelength allocated to the corresponding WPMC and WPSC and is defined as a total of 6 bits in consideration of the extension of the WDM-PON. The frame type (FT) area 234 indicates the type of message and allocates 3 bits so that the frame type (FT) may be divided into eight. Finally, the sub_information area 236 is composed of 21 bits and takes a different form according to the frame type.

Tables 1 and 2 below show details of the field values of the sub information section 236 of FIG. 7B.

TABLE 1

All four frame types are defined and used in the WPMC direction. The SET type transmitted from the WPMC means setting the ONT wavelength control value to the wavelength control value in the sub information. The GET type means reporting the current wavelength control value to the WPMC. The AD type means that the WPMC sets the control range (MIN ~ MAX) and the control width (STEP) to the WPSC. This message is used at the beginning of wavelength alignment. The STOP type is a message that causes ONT to immediately stop automatic wavelength alignment and maintain the link state by maintaining the current control value. Two frame types are defined in both WPSC and WPMC directions. First, the REPORT type is a message type for reporting the WCI for the currently transmitted optical signal to the WPMC. The WPSC sends the WCI of the currently transmitted optical signal to the OLT in a REPORT message. When the ACK receives the SET command from the WPMC, the ACK is used to report the control value to the WPMC after controlling the wavelength accordingly.

TABLE 2

Table 2 shows an example of information included in each frame type and the number of allocated bits.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD_ROM, magnetic tape, floppy disks, and optical data storage, and may also include those implemented in the form of carrier waves (e.g., transmission over the Internet). . The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

So far, the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. will be. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described in detail above, the WDM-PONs of the present invention include WPMCs in OLT and WPSCs in ONT in a WDM-PONs including a variable wavelength light source, and use a table configuration algorithm and an optimal value determination algorithm. By automatically aligning the light sources to their assigned wavelengths, the automatic wavelength initialization of WDM-PONs can be performed.

In addition, the present invention is very easy to install, operate, and manage the ONT device because wavelength alignment is automatically performed without user intervention, and the automatic alignment function automatically adapts to changes in line characteristics with temperature and time, thereby improving network availability. Can increase significantly.

Furthermore, the variable wavelength remote monitoring / control function using the WPMC, WPSC and AWG according to the present invention can significantly reduce the network construction cost by replacing the function of the conventional expensive wavelength locker, In this way, the manufacturing efficiency can be improved by easing the restriction on the fixed correspondence between the control value and the output light wavelength.

Claims (37)

In Wavelength Division Multiplexing Passive Optical Networks (WDM-PONs), An optical line terminal (OLT) including an optical subscriber network main control unit (WDM-PONs Master Control (WPMC)) for wavelength initialization in a physical layer; An optical network terminus (ONT) including a tunable laser diode (TLD) and an optical subscriber network sub-control unit (WPSC) for initializing wavelengths in a physical layer; And An outdoor node (RN) for relaying the base station transmitting end and the subscriber end; And a wavelength division multiplexing passive optical subscriber network capable of initializing wavelengths of the TLD by exchanging wavelength initialization information between the WPMC and the WPSC. According to claim 1, The WPSC varies the wavelength of the TLD while changing a Wavelength Control Index (WCI), and the WPMC receives the power of an optical signal corresponding to each of the WCI and the WCI to determine an optimal WCI. To, And the wavelength initialization information includes the WCI, power of an optical signal, and an optimal WCI. The method of claim 2, The OLT includes a power monitoring entity (PME) for observing the optical power of the received optical signal and transmitting the optical power to the WPMC. The ONT includes a wavelength division multiplexing passive optical subscriber network for receiving an optimal WCI transmitted from the WPMC to the WPSC, converting it into a wavelength control signal, and transmitting the wavelength control signal to the WPSC. . The method of claim 2, And the optical signal corresponding to each of the WCIs is filtered through an arrayed waveguide grating (AWG). The method of claim 2, And the WPMC uses an optimal value algorithm to determine the optimal WCI value. The method of claim 5, The optimal value algorithm is A table construction algorithm for preparing values of parameters including the WCI and measured optical power; And And an optimum value determination algorithm for determining an optimum control value using the values created through the table configuration algorithm. The method of claim 6, The parameters of the table configuration algorithm may include: a monitoring power (MP) corresponding to each of the WCI, the WCI, a number corresponding to each of the WCIs (Number: N), and a partition number to which the WCI belongs; PN), and the partition length (PL) of the wavelength division multiplexing passive optical subscriber network. The method of claim 7, wherein The optimal value determination algorithm, A wavelength division multiplexing passive optical subscriber network comprising an optimal control value (I _opt ), an optimal length (OL), an optimal partition (OP), a number (N), and an optimal number (ON) as decision parameters. The method of claim 2, The ONT is configured to use the first time clocks after the WPSC is powered on or reset. Receiving an Advertisement (AD) message from the WPMC, setting the WCI to an initial value, transmitting an optical signal having a wavelength corresponding to the WCI to the WPMC while changing the WCI, and obtaining an optimal WCI from the OLT. A wavelength division multiplexing passive optical subscriber network comprising: receiving and performing a wavelength initialization function. The method of claim 9, The first time clocks, An inter-frame guard time (IFGT) corresponding to an interval between periodic transmissions of an optical signal having a wavelength corresponding to the WCI in the step of transmitting to the WPMC; An optical stabilization guard time (OSGT) corresponding to the time required for the optical stabilization time of the changed optical signal; A clock lock time (CLT) corresponding to a time for restoring a clock of the received optical signal in the OLT; And Stabilization and Clock Lock Guard Time (SCGT) corresponding to the sum of the change in the WCI and the optical signal clock recovery time (SCGT); and the wavelength division multiplexing passive optical subscriber network. The method of claim 2, The OLT is configured to use the second time clocks after the WPMC is powered on or reset. A table configuration algorithm for sending an AD message to the WPSC, receiving an optical signal including the WCI from the WPSC, and writing values of parameters including the WCI and measured optical power; A wavelength division multiplexing passive type is used to determine an optimal WCI using an optimal value algorithm including an optimal value determination algorithm for determining an optimal control value, and transmits the optimal WCI to the WPSC to perform a wavelength initialization function. Optical subscriber network. The method of claim 11, wherein The second time clocks, A Search Loop Time (SLT) corresponding to the time required to monitor the received power for the entire variable band; Acknowledgment Time (ACKT) corresponding to the time to wait to receive an acknowledgment (ACK) message including the optimal WCI from the WPSC after determining an optimal WCI; And And a Message Interval Time (MIT) corresponding to the transmission interval of the AD message. The method of claim 2, The frame structure of the WDM-PONs Control Protocol (WPCP) for initializing the wavelength of the optical subscriber network includes an idle code (/ C /) region and a configuration ordered set (/ C /). ) Area and information area, And the structure alignment set region is used to perform the wavelength initialization function. The method of claim 13, The WPMC extracts a frame that is encapsulated into the structure alignment set from a binary code received from an optical transceiver, or encapsulates and inserts the frame into the structure alignment set. Multiplexed Passive Optical Subscriber Network. The method of claim 13, The information region has a wavelength identification (WID) region, a frame type (FT) region indicating a message type, and sub-information for storing a specific value of a field having a different form according to the FT. Wavelength division multiplexing passive optical subscriber network comprising a) region. The method of claim 15, And the FT includes four frame types defined in the WPMC direction in the WPSC direction and two frame types defined in the WPSC in the WPSC direction. The method of claim 16, The four frame types include a SET type that sets the wavelength control value of the ONT, a GET type that reports the current wavelength control value to the WPMC, secures control synchronization between remote nodes, and controls the control range and the WCI. An AD type for setting the control width Δi at predetermined intervals between the values in the WPSC, and a STOP for causing the ONT to stop the wavelength initialization function and maintain the current control value to maintain the link state. ) Type, The two frame types report the WCI on the currently transmitted optical signal to the WPMC, and when receiving a set command from the WPMC, reports a control value to the WPMC after controlling a wavelength. A wavelength division multiplexing passive optical subscriber network comprising an ACK type. The optical signal transmission method of claim 1, wherein the wavelength division multiplexing passive optical networks (WDM-PONs), And a wavelength division multiplexing passive optical subscriber network for initializing the wavelength of the TLD. The method of claim 18, The OLT includes a power monitoring entity (PME) for observing the power of the received optical signal and transmitting the power to the WPMC, and the ONT receives the optimal WCI transmitted from the WPMC to the WPSC and transmits the wavelength control signal. A wavelength control unit (WCE) for converting The WPSC varies the wavelength of the TLD while changing a Wavelength Control Index (WCI), the WPMC receives the power of the optical signal corresponding to the WCI and each WCI, and determines an optimal WCI value. And the wavelength initialization information comprises the WCI, power of an optical signal, and an optimal WCI. The method of claim 19, The wavelength initialization method, A table construction algorithm for preparing values of parameters including the WCI and measured optical power; And And an optimum value determination algorithm for determining an optimum control value using the values created by the table configuration algorithm. The method of claim 20, The parameters of the table configuration algorithm may include: a monitoring power (MP) corresponding to each of the WCI, the WCI, a number corresponding to each of the WCIs (Number: N), and a partition number to which the WCI belongs; PN), and the partition length (PL), The table configuration algorithm, Setting an initial value to the parameters; The OLT receiving an optical signal including the WCI from the ONT; Comparing the MP of the optical signal with a sum of a System Power Margin (SPM) and a Receiver Sensitivity (RS) of the receiver; If the MP is greater than or equal to the SPM + RS, the sum of the control width Δi of the predetermined interval between the WCI (Before WCI: BWCI) and the WCI values, which is increased by 1 to the N and immediately before the WCI is received. Comparing with; And And writing the parameters in the table according to the comparison result. The wavelength initialization method of a wavelength division multiplexing passive optical subscriber network comprising: a. The method of claim 21, Creating the table If the WCI is equal to BWCI + Δ in the comparing step, increase the PL to 1, and write the WCI, MP, N, PN and PL to the table, If the WCI is not equal to BWCI + Δ in the comparison step, increase the value of 1 in the PN, write the PL value in the partition length description parts corresponding to PN-1 in the table, and store 1 in the PL. And WCI, MP, N, PN, and PL are written in the table. The method of claim 21, If the MP is smaller than the SPM + RS, return to the step of receiving the optical signal, Returning to the step of receiving the optical signal after the preparation step, The table configuration algorithm terminates when a Search Loop Time_out (SLT_out) signal or an algorithm termination signal is received in the receiving step. The method of claim 21, The initial value of the parameters BWCI, N, PL is set to 0, the PN is set to 1, characterized in that the wavelength division multiplexing passive optical subscriber network. The method of claim 21, The optimal value determination algorithm, Determination parameters include optimal control value (I _opt ), optimal length (OL), optimal partition (OP), number (N) and optimal number (ON), A setting step of setting an initial value to the determination parameters; A comparison step of reading the WCI, MP, PN and PL data written in the table and comparing the OL with the PL; A changing step of changing a value of the determination parameters in accordance with a result of the comparing step; A checking step of checking whether the table is at the end; And And an input step of inputting the WCI corresponding to the ON into the I _opt when the table is at the end of the table in the inspection step. The method of claim 25, The comparing step A first comparing step of comparing the OL and the PL; A second comparing step of determining whether the OL is equal to the PL when the OL is less than or equal to the PL; And A third comparison step of comparing the OP and the PN in the same case; If OP and PN are different in the third comparison step, enter into the change step, and if OP and PN are the same, increase 1 to N, skip the change step, and enter the inspection step, If it is different from the second comparison step, the process directly enters the change step, If the OL is greater than the PL in the first comparison step, increase the 1 to N, skip the change step and enter the inspection step, In the changing step, N + [PN / 2] in the ON, PL in the OL, N + PL in the N, and PN in the OP, respectively, wherein [] represents a mathematical symbol of truncation Wavelength initialization method of wavelength division multiplexing passive optical subscriber network. The method of claim 26, If the end of the table in the inspection step, the wavelength division multiplexing passive optical subscriber network, characterized in that entering into the comparison step. The method of claim 26, The initial values of the determination parameters are I _opt , OL and OP are 0 and N and ON are set to 1, the wavelength initializing method of the wavelength division multiplexing passive optical subscriber network. The method of claim 19, The ONT is configured to use the first time clocks after the WPSC is powered on or reset. Receiving an advertising (AD) message from the WPMC; Setting the WCI to an initial value; Transmitting an optical signal having a wavelength corresponding to the WCI to the WPMC while changing the WCI; And Receiving a WCI from the OLT; and performing a wavelength initialization function through the wavelength division multiplexing passive optical subscriber network. The method of claim 29, The step of transmitting to the WPMC is, before proceeding to the optimal WCI receiving step, And periodically transmitting an optical signal having a wavelength corresponding to the WCI to the WPMC. The method of claim 29, The first time clocks, An Inter-Frame Guard Time (IFGT) corresponding to the interval between periodic transmissions of the changed optical signal in the step of transmitting to the WPMC; An optical stabilization guard time (OSGT) corresponding to the time required for the optical stabilization time of the changed optical signal; A clock lock time (CLT) corresponding to a time for restoring a clock of the received optical signal in the OLT; And Stabilization and Clock Lock Guard Time (SCGT) corresponding to the sum of the change of the WCI and the optical signal clock recovery time (SCGT); Wavelength initialization of the wavelength division multiplexing passive optical subscriber network Way. The method of claim 29, The change in the WCI increases with a predetermined interval between the set minimum value and the maximum value, and stops when the optimum WCI is received, characterized in that the wavelength division multiplexing passive optical subscriber network initialization method. The method of claim 29, When the WPSC receives the optimal WCI value, the WPSC sends an acknowledgment (ACK) message including the optimal WCI value to the WPMC and terminates the wavelength initialization function. The optical signal transmission is performed with the optical power corresponding to the optimal WCI, but if an error occurs in the optical signal transmission, the wavelength division multiplexing passive optical subscriber network of the wavelength division multiplexing, characterized in that the process proceeds again. Wavelength initialization method. The method of claim 19, The OLT is configured to use the second time clocks after the WPMC is powered on or reset. Sending an AD message to the WPSC; Receiving an optical signal including the WCI from the WPSC; Optimal using an optimal value algorithm including a table configuration algorithm for preparing values of parameters including the WCI and measured optical power and an optimal value determination algorithm for determining an optimal control value using the values created through the table configuration algorithm. Determining a WCI; Transmitting the optimal WCI to the WPSC; and performing a wavelength initialization function over the wavelength division multiplexing passive optical subscriber network. The method of claim 34, wherein In the AD message transmitting step, before the WCI receiving step proceeds, the AD message is periodically transmitted to the WPSC. The AD message includes wavelength identification (WID) assigned to each port, the minimum and maximum values of the WCI, and information on the control width Δi at a predetermined interval between the WCI values. Wavelength initialization method of passive optical subscriber network. The method of claim 34, wherein The second time clocks, A Search Loop Time (SLT) corresponding to the time required to monitor the received power for the entire variable band; Acknowledgment Time (ACKT) corresponding to the time to wait to receive an acknowledgment (ACK) message including the optimal WCI from the WPSC after determining an optimal WCI; And And a Message Interval Time (MIT) corresponding to the transmission interval of the AD message. The method of claim 36, wherein After the optimal WCI determination step, When the WPMC receives an acknowledgment (ACK) message including the optimal WCI from the WPSC during the ACKT time, the WPMC terminates the wavelength initialization function and performs a transmission function for an optical signal having an optical power corresponding to the optimal WCI. If an error occurs in the transmission of the optical signal, the process proceeds to the step of transmitting the AD message of the initial wavelength and function again If the acknowledgment (ACK) message is not received, the wavelength division multiplexing passive optical subscriber network, characterized in that the step of transmitting to the AD message transmission method.

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