WO2017070835A1

WO2017070835A1 - Wavelength locking method, network device and wdm pon system

Info

Publication number: WO2017070835A1
Application number: PCT/CN2015/092933
Authority: WO
Inventors: 徐之光; 周敏; 林华枫
Original assignee: 华为技术有限公司
Priority date: 2015-10-27
Filing date: 2015-10-27
Publication date: 2017-05-04

Abstract

Provided are a wavelength locking method, a network device and a WDM PON system. The method comprises: a first OLT receiving and acquiring pulse optical signals of all wavelengths scanned and transmitted by a first ONU one by one and supported by a WDM PON system, and optical powers thereof; and from the optical powers of the pulse optical signals of all wavelengths, determining a wavelength corresponding to the maximum optical power and transmitted by the first ONU to be a target wavelength of the first ONU so as to enable the first ONU to communicate with the first OLT according to the target wavelength.

Description

Wavelength locking method, network device and WDM PON system

Technical field

The embodiments of the present invention relate to the field of network device technologies, and in particular, to a wavelength locking method, a network device, and a WDM PON system.

Background technique

As the amount of communication information increases, the demand for bandwidth is increasing. The fiber access network, especially the Wavelength Division Multiplexing (WDM) Passive Optical Network (PON). The system has become the main force of information transmission. The WDM-PON system uses an Arrayed Waveguide Grating (AWG) to implement wavelength division multiplexing. In the WDM-PON system, there is an AWG at the transmitting end and the receiving end respectively, and the multiplexed ports of the two AWGs are connected by optical fibers, an optical network unit (ONU) and an optical line terminal (Optical Line Terminal, OLT for short). ) respectively connected to the branching port of the AWG, and the ONU and the OLT respectively form a communication link through a specific wavelength. The AWG is used as the wavelength routing of the WDM-PON system. Multiple sets of wavelength links are aggregated and transmitted on one trunk fiber. On the side of the splitter port of the AWG, each wavelength is separately connected to the respective optical modules.

Because the colorless WDM-PON optical module system has a single wavelength, tunable and reusable wavelength, the colorless WDM-PON optical module system has a higher storage cost than the colored optical module system with fixed wavelength and many models. Small, more widely used. At present, when a colorless WDM-PON optical module system is used, since the AWG channel parameters connected to it are unknown, when a new ONU is online, it is necessary to adjust the wavelength of the continuous optical signal scanned and transmitted by the new ONU until the new ONU is ON. The wavelength of the transmitted continuous optical signal is exactly the same as the wavelength of the corresponding AWG channel.

However, in the above-mentioned wavelength locking method provided by the prior art, since the newly-online ONU transmits a continuous optical signal during the wavelength adjustment process, it will crosstalk the communication link originally in the normal communication state, resulting in the original online communication chain. The communication interruption of the road affects the communication quality of the WDM-PON system.

Summary of the invention

The embodiment of the invention provides a wavelength locking method, a network device and a WDM PON system, so as to solve the communication link of the continuous optical signal transmitted by the new ONU in the wavelength adjustment process in the existing WDM PON system to the communication state originally in the normal communication state. The crosstalk problem generated improves the communication quality of the WDM-PON system.

The first aspect provides a wavelength locking method, which is applied in a WDM PON system of a wavelength division multiplexing passive optical network, where the WDM PON includes: at least two ONUs and at least two OLTs, and the first ONU is newly launched. An ONU, the second ONU is an ONU, the first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link. Methods include:

The first OLT receives pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one; wherein the duty ratios of the pulse optical signals of all wavelengths are the first duty Comparing, the first duty ratio is determined according to an error correction capability of the second communication link;

Obtaining, by the first OLT, optical power of the pulsed optical signals of all wavelengths according to the pulsed optical signals of all wavelengths;

Determining, by the optical power of the pulsed optical signals of all the wavelengths, a wavelength emitted by the first ONU corresponding to the maximum optical power is a target wavelength of the first ONU, so that the first ONU is based on the target wavelength The first OLT communicates.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the first duty ratio is determined according to an error correction capability of the second communications link, and specifically includes:

When the first ONU scans and transmits a pulsed optical signal of any duty ratio to the first OLT one by one, the second OLT detects the pulsed optical signal on the second communication link;

If the second OLT determines that the error of the pulsed optical signal to the second communication link can be corrected by the RS (255, 239) encoding of the FEC of the second communication link, and the error rate is less than The error rate specified by the WDM PON system, the value of the duty ratio adopted by the first ONU at this time is set to the value of the first duty ratio;

The ratio of the any one of the duty ratios is less than or equal to (255-239) / (255 - (255 - 239)), and is greater than or equal to the first threshold, the first threshold is according to the first OLT Detection performance and power resolution accuracy are determined.

In conjunction with the first possible implementation of the first aspect, in a second possible implementation manner of the first aspect, the method further includes:

The first OLT receives and acquires pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one and their corresponding optical powers;

According to the detection performance and power resolution accuracy of the first OLT, among the optical powers of all the received pulsed optical signals that the first OLT can detect and can distinguish, the pulse optical signals corresponding to the maximum optical power are selected. The null ratio is the first threshold.

With reference to any one of the possible implementations of the first to the second possible implementations of the first aspect, in the third possible implementation manner of the first aspect, when the second communication link adopts an RS of FEC ( When 255, 239) is encoded, the value of the first duty ratio is 3/255-3, or 4/255-4.

The second aspect provides a wavelength locking method, which is applied to a wavelength division multiplexing passive optical network WDM PON, where the WDM PON includes: at least two ONUs and at least two OLTs, and the first ONU is a new ONU The second ONU is connected to the ONU, the first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link. include:

The first ONU scans and transmits the pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT one by one; wherein the duty ratios of the pulsed optical signals of all wavelengths are the first duty ratio, Determining a first duty cycle according to an error correction capability of the second communication link;

The first ONU adjusts its own wavelength to the target wavelength according to the target wavelength determined by the first OLT, wherein the target wavelength is the first scanning and transmitting by the first OLT according to the first ONU. Determining the optical power of a pulsed optical signal of all wavelengths of a duty cycle;

The first ONU communicates with the first OLT according to the target wavelength.

With reference to the second aspect, in a first possible implementation manner of the second aspect, when the second communications link uses the RS (255, 239) encoding of the FEC, the ratio of the first duty ratio is less than or equal to (255-239) / (255-(255-239)).

With reference to the second aspect, in a second possible implementation manner of the second aspect, the ratio of the first duty ratio is greater than or equal to a first threshold, where the first threshold is based on detection performance and power of the first OLT Resolution accuracy is determined.

With reference to the second possible implementation of the second aspect, in a third possible implementation manner of the second aspect, the method further includes:

The first ONU scans and transmits the pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT one by one, so that the first OLT is detected according to the first OLT. Performance and power resolution accuracy, in the optical power of all the received pulsed light signals that the first OLT is capable of detecting and capable of distinguishing, the duty ratio of the pulsed optical signal corresponding to the maximum optical power is selected as a first threshold;

The first ONU receives the first threshold determined by the first OLT.

With reference to any one of the first to third possible implementation manners of the second aspect, in the fourth possible implementation manner of the second aspect, when the second communication link adopts an FEC RS ( When 255, 239) is encoded, the value of the first duty ratio is 3/255-3, or 4/255-4.

The third aspect provides a network device, where the network device is located at a central office side of a WDM PON of a wavelength division multiplexing passive optical network, where the WDM PON includes: at least two ONUs and at least two OLTs, and the first ONU is new On the ONU, the second ONU is the ONU, the first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link. The network device is the first OLT, and includes:

a first transceiver, configured to receive pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one; wherein a duty ratio of the pulse optical signals of all wavelengths is first a duty ratio, the first duty ratio being determined according to an error correction capability of the second communication link;

An acquiring unit, configured to obtain optical powers of the pulsed optical signals of all the wavelengths according to the pulsed optical signals of all the wavelengths;

a processor, configured to determine, in an optical power of the pulsed optical signals of all the wavelengths, a wavelength emitted by the first ONU corresponding to the maximum optical power as a target wavelength of the first ONU, so that the first ONU is configured according to the The target wavelength is in communication with the first OLT.

With reference to the third aspect, in a first possible implementation manner of the third aspect, when the second communications link uses the RS (255, 239) encoding of the FEC, the ratio of the first duty ratio is less than or equal to (255-239) / (255-(255-239)).

With reference to the third aspect, in a second possible implementation manner of the third aspect, the ratio of the first duty ratio is greater than or equal to a first threshold, and the first threshold is determined according to detection performance and power of the network device The accuracy is determined.

With reference to the second possible implementation manner of the third aspect, in a third possible implementation manner of the third aspect, the first transceiver is further configured to receive and acquire, by the first ONU, scanning and transmitting one by one The pulsed optical signals of all wavelengths supported by the WDM PON system and their corresponding optical powers;

The acquiring unit is further configured to: according to the detection performance and the power resolution precision of the network device, select, according to the optical power of all the received pulse optical signals that the acquiring unit can detect and can distinguish, the maximum optical power is selected. The duty cycle value of the pulsed optical signal is a first threshold.

With reference to any one of the first to third possible implementation manners of the third aspect, in a fourth possible implementation manner of the third aspect, when the second communication link adopts an FEC RS ( When 255, 239) is encoded, the value of the first duty ratio is 3/255-3, or 4/255-4.

The fourth aspect provides a network device, where the network device is located at a terminal side of a WDM PON of a wavelength division multiplexing passive optical network, where the WDM PON includes: at least two ONUs and at least two OLTs, and the first ONU is newly launched. An ONU, the second ONU is an ONU, the first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link. The network device is the first ONU, including:

a second transceiver, configured to scan and transmit pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT one by one; wherein a duty ratio of the pulse optical signals of all wavelengths is first a ratio of the first duty ratio determined according to an error correction capability of the second communication link;

a wavelength adjustment unit, configured to adjust a self wavelength to the target wavelength according to the target wavelength determined by the first OLT, wherein the target wavelength is that the first OLT scans and transmits one by one according to the first ONU The optical power of the pulsed optical signals of all wavelengths of the first duty cycle is determined;

The second transceiver is further configured to communicate with the first OLT according to the target wavelength.

With reference to the fourth aspect, in a first possible implementation manner of the fourth aspect, when the second communications link uses the RS (255, 239) encoding of the FEC, the ratio of the first duty ratio is less than or equal to (255-239) / (255-(255-239)).

With reference to the fourth aspect, in a second possible implementation manner of the fourth aspect, the ratio of the first duty ratio is greater than or equal to a first threshold, and the first threshold is based on detection performance and power of the first OLT Resolution accuracy is determined.

In conjunction with the second possible implementation of the fourth aspect, in a third possible implementation manner of the fourth aspect, the second transceiver is further configured to scan and transmit the pulses of all wavelengths supported by the WDM PON system one by one. And transmitting, by the first OLT, the first OLT, according to the detection performance and power resolution precision of the first OLT, all the light that receives the pulsed light signal that can be detected and can be resolved by the first OLT In the power, the duty ratio of the pulsed optical signal corresponding to the maximum optical power is selected as a first threshold for receiving the first threshold determined by the first OLT.

With reference to any one of the first to third possible implementation manners of the fourth aspect, in a fourth possible implementation manner of the fourth aspect, when the second communication link adopts an FEC RS ( When 255, 239) is encoded, the value of the first duty ratio is 3/255-3, or 4/255-4.

The fifth aspect provides a WDM-PON system, where the WDM PON system includes: at least two ONUs and at least two OLTs, the first ONU is a new ONU, the second ONU is an ONU, and the first ONU is The first OLT is connected by a first communication link, and the second ONU is connected to the second ONU by a second communication link, where the first OLT is in any possible implementation manner of the third aspect. The network device, the first ONU is the network device described in any one of the possible implementation manners of the fourth aspect.

The wavelength locking method, the network device, and the WDM PON system provided by the embodiment of the present invention are connected between the new ONU and the first OLT through the first communication link, and the second ONU is connected between the ONU and the second ONU. a pulsed optical signal of all wavelengths supported by the WDM PON system scanned and transmitted one by one by the new ONU ONU. The duty ratio of the pulsed optical signals of all wavelengths is the first duty ratio, and the first duty ratio is based on The error correction capability of the second communication link determines that the first OLT determines, according to the received optical power of the pulsed optical signals of all wavelengths, that the wavelength of the new uplink ONU corresponding to the maximum optical power is the target of the new ONU The wavelength enables the new on-line ONU to communicate with the first OLT according to the target wavelength, which solves the problem that the newly-online ONU emits a continuous optical signal in the process of wavelength adjustment in the existing wavelength locking method to the original normal communication state. The crosstalk problem generated by the communication link improves the communication quality of the WDM-PON system.

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are some embodiments of the present invention. One of ordinary skill in the art can also obtain other drawings based on these drawings without paying for inventive labor.

1 is a schematic structural view of a WDM-PON system;

2 is a schematic flowchart of Embodiment 1 of a wavelength locking method according to an embodiment of the present disclosure;

FIG. 3 is a schematic flowchart diagram of Embodiment 2 of a wavelength locking method according to an embodiment of the present disclosure;

4 is a schematic flowchart of Embodiment 3 of a wavelength locking method according to an embodiment of the present disclosure;

FIG. 5 is a schematic flowchart diagram of Embodiment 4 of a wavelength locking method according to an embodiment of the present disclosure;

FIG. 6 is a schematic flowchart of Embodiment 1 of a network device according to an embodiment of the present disclosure;

FIG. 7 is a schematic flowchart of Embodiment 2 of a network device according to an embodiment of the present disclosure;

FIG. 8 is a schematic structural diagram of Embodiment 1 of a WDM-PON system according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. It is a partial embodiment of the invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

With the rapid increase in the amount of mobile communication information, users have higher and higher demand for bandwidth. The traditional copper bandwidth access system can no longer meet the user's demand for bandwidth. At the same time, the fiber-optic communication technology with huge bandwidth capacity is becoming more and more mature. The fiber access network, especially the Wavelength Division Multiplexing (WDM) PON system, has become the main force for transmitting communication information.

FIG. 1 is a schematic structural view of a WDM-PON system. The WDM-PON system uses an Arrayed Waveguide Grating (AWG) to implement wavelength division multiplexing. For ease of analysis, the present invention is described by taking a WDM-PON system including two ONUs, two OLTs, and two AWGs as an example.

As shown in FIG. 1 , the first ONU 11 and the second ONU 12 are connected to the split port of the first AWG 13 , and the first OLT 14 and the second OLT 15 are connected to the split port of the second AWG 16 , and the first AWG 13 is connected. It is connected to the multiplex port of the second AWG 16 via an optical fiber 17. It is assumed that the first ONU 11 is a new uplink ONU, the second ONU 12 is an online ONU, the first ONU 11 is connected to the first OLT 14 through a first communication link, and the second ONU 12 is passed between the second ONU 12 and the second OLT 15. The second communication link is connected, and a first communication link is formed between the first ONU 11 and the first OLT 14 by the first wavelength λ1, and the second ONU 12 and the second OLT 15 form a second communication by the second wavelength λ2. The link, the first AWG 13 and the second AWG 16 serve as wavelength routing for the WDM-PON system, and both sets of wavelength links are concentrated on one backbone fiber 17 for transmission, while the first AWG 13 and the second AWG 16 are On the port side, each wavelength is separately connected to the respective optical module.

For example, in FIG. 1, the signal transmitted by the first ONU 11 passes through a routing channel between the first ONU 11 and the first AWG 13, an optical fiber 17 between the first AWG 13 and the second AWG 16, and a second The routing channel between the AWG 16 and the first OLT 14 is transmitted to the first OLT 14.

FIG. 2 is a schematic flowchart diagram of Embodiment 1 of a wavelength locking method according to an embodiment of the present invention. The wavelength locking method provided by the embodiment of the present invention is described by using the central office side OLT as a main body. As shown in FIG. 2, the wavelength locking method provided in Embodiment 1 of the present invention is applied to the WDM PON system shown in FIG. 1. As shown in FIG. 2, the wavelength locking method includes:

Step 201: The first OLT 14 receives the pulsed optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU 11 one by one.

The duty ratio of the pulsed optical signals of all wavelengths is the first duty ratio, and the first duty ratio is determined according to the error correction capability of the second communication link.

In the case where the duty ratio of the pulsed optical signal is determined, the first ONU 11 located on the terminal side of the WDM PON system scans and transmits the pulsed optical signals of all wavelengths supported by the WDM PON system one by one in a certain order, and is located in the WDM PON system. The first OLT 14 on the central office side sequentially receives the pulsed optical signals of all the above wavelengths.

Step 202: The first OLT 14 obtains the optical power of the pulsed optical signals of all wavelengths according to the pulsed optical signals of all wavelengths.

The first OLT 14 is capable of detecting and receiving the pulsed light signals of all the above wavelengths, and knows the optical power of the pulsed light signals of all wavelengths according to the optical power detectors disposed in the first OLT 14.

Step 203: In the optical power of the pulsed optical signals of all wavelengths, determine that the wavelength of the first ONU 11 corresponding to the maximum optical power is the target wavelength of the first ONU 11, so that the first ONU 11 is based on the target wavelength and the first OLT. 14 communicate.

In the case where the pulsed optical signal scanned and transmitted by the first ONU 11 is of the same duty ratio, if the wavelength of the pulsed optical signal emitted by the first ONU 11 is the same as the routing channel wavelength of the first AWG 13, and the routing path of the second AWG 16 When the wavelengths are consistent, the pulsed optical signal transmitted by the first ONU 11 loses less energy in the first communication link, and the first OLT 14 can receive the power of most of the pulsed optical signals. At this time, the first OLT 14 receives the same. The power of the pulsed optical signal is substantially equal to the power of the pulsed optical signal scanned and transmitted by the first ONU 11; if the wavelength of the pulsed optical signal emitted by the first ONU 11 is the same as the routing channel wavelength of the first AWG 13, the second AWG 16 If the routing channel wavelengths are inconsistent, then the routing channel of the first AWG 13 and the routing channel of the second AWG 16 will mask most of the pulsed optical signals. For the pulsed optical signals of the same power, at this time, the first OLT 14 receives the signals. The power of the pulsed light signal is small.

Since the duty ratios of the pulse optical signals of all the wavelengths received by the first OLT 14 are determined, the optical powers of the pulse optical signals of all the wavelengths scanned and transmitted by the first ONU 11 are equal, if the first When the optical power of the pulsed optical signal corresponding to a certain wavelength received by the OLT 14 is the largest, it can be considered that the communication quality of the first communication link is the best when the first ONU 11 and the first OLT 14 are routed at the wavelength. Therefore, the wavelength of the first ONU 11 corresponding to the optical power of the pulsed optical signal received by the first OLT 14 is determined to be the target wavelength of the first ONU 11, so that the first ONU 11 and the first OLT 14 pass the The target wavelength is communicated.

According to the wavelength locking method provided by the first embodiment of the present invention, the first OLT receives and acquires pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one and their corresponding optical powers, and from all the above wavelengths In the optical power of the pulsed optical signal, the wavelength of the first ONU corresponding to the maximum optical power is selected as the target wavelength of the first ONU, so that the first ONU communicates with the first OLT according to the target wavelength, due to the pulse of all the above wavelengths. The duty ratio of the optical signal is the first duty ratio, and the first duty ratio is determined according to the error correction capability of the second communication link. Therefore, using the wavelength locking method provided by the embodiment of the present invention, the first When the ONU is newly online, crosstalk will not be generated to the adjacent second communication link, which solves the problem that the continuous optical signal transmitted by the new ONU in the wavelength adjustment process will be in the normal communication state in the existing wavelength locking method. The crosstalk problem generated by the communication link improves the communication quality of the WDM-PON system.

Further, in the wavelength locking method provided in the first embodiment, the first duty ratio is determined according to the error correction capability of the second communication link, and specifically includes:

When the first ONU 11 scans and transmits a pulsed optical signal of any duty ratio to the first OLT 14, the second OLT 15 detects the pulsed optical signal on the second communication link; and if the second OLT 15 Determining that the error of the pulsed optical signal to the second communication link can be corrected by the RS (255, 239) encoding of the FEC of the second communication link, and the error rate is less than the error rate specified by the WDM PON system, The value of the duty ratio employed by an ONU 11 at this time is set to the value of the first duty ratio.

The ratio of any one of the above-mentioned duty ratios is less than or equal to (255-239)/(255-(255-239)), and is greater than or equal to a first threshold, which is based on the detection performance of the first OLT 14. And power resolution accuracy is determined.

Specifically, it is assumed that the first communication link between the first ONU 11 (the newly-online ONU) and the first OLT 14 and the second between the second ONU 12 (the ONU that has been on the line) and the second OLT 15 The communication links are all encoded by FEC's RS (255, 239). Then, the method for determining the first duty cycle is summarized as follows:

First, since the first communication link and the second communication link both use the RS (255, 239) encoding of the FEC, that is, the FEC algorithm can accommodate a maximum of (255-239) bytes of errors, so The upper limit of the duty ratio of the pulsed light signal is set to (255 - 239) / (255 - (255 - 239)).

In the embodiment of the present invention, the principle of the FEC algorithm is summarized as follows: in the second communication link of normal communication, the second ONU 12 sends a certain redundant error correction code to the data to be sent, and communicates with the normal communication. The second OLT 15 performs error detection on the data according to the received redundant error correction code. If an error is found, the second OLT 15 corrects the data to ensure that the second communication link that is in the normal communication state transmits data. Correctness.

Secondly, the first ONU 11 starts from the minimum duty ratio, that is, firstly scans and emits a pulsed optical signal of a certain wavelength with a 1:0 duty ratio of 1/255-1, specifically, 1 The byte is high, indicating "1", and the remaining 254 bytes are low, indicating "0", that is, the duty ratio of 1 and 0 is 1:254. If the first OLT 14 is capable of detecting the pulsed optical signal of the above-mentioned certain wavelength emitted by the first ONU 11, it is considered that 1/255-1 is the lower limit of the duty ratio of the pulsed optical signal; otherwise, the first ONU 11 is sequentially scanned. And transmitting a high-low level duty ratio of the pulsed optical signal of a certain wavelength until the first OLT 14 can detect the pulsed optical signal emitted by the first ONU 11. Assuming that the condition that satisfies the first OLT 14 detection performance and power resolution accuracy is the first threshold, then it may be determined that the first threshold is the lower limit of the duty ratio of the pulsed optical signal that the first ONU 11 is to scan and emit.

Optionally, the first threshold may be determined by a difference between a maximum optical power and a second large optical power of optical powers of all the pulsed optical signals received by the first OLT 14. At this time, the first OLT 14 must be able to detect and detect the maximum optical power and the second large optical power.

In practical applications, the greater the duty ratio of the pulsed optical signal scanned and transmitted by the first ONU 11, the easier the first OLT 14 receives the pulsed optical signal transmitted by the first ONU 11, and therefore, the easier the first ONU 11 Determining the wavelength of the first communication link between the first ONU 11 and the first OLT 14, but if the duty cycle of the pulsed optical signal scanned and transmitted by the first ONU 11 is larger, it is in the WDM-PON system The greater the crosstalk caused by the second communication link in the normal communication state, the crosstalk may not be corrected by the RS (255, 239) encoding of the FEC on the second communication link. Therefore, the duty ratio of the pulsed optical signal is too large or too small, and it is required to satisfy a certain condition, that is, greater than or equal to the lower limit of the duty ratio of the pulsed optical signal, and less than or equal to the above pulse. The upper limit of the duty cycle of the impulse signal.

Again, the first ONU 11 first scans and transmits the pulsed light of all wavelengths supported by the WDM PON system one by one with the upper limit (255-239) / (255-(255-239)) of the duty ratio determined above as the duty ratio. Signaling to the first OLT 14, when the second OLT 15 detects that the second communication link between the second ONU 12 and the second OLT 15 is crosstalked, detecting the error correction capability of the FEC, determining that the first ONU 11 is given The crosstalk caused by the pulsed optical signal transmitted by the OLT 14 to the second communication link causes the error rate to be within the error range specified by the WDM PON system. If yes, it is determined that (255-239)/(255-(255-239)) is the first duty ratio to be determined, otherwise, (255-239-n)/(255-(255-239-n) (where n is an integer greater than or equal to 1 and less than 16) is the duty ratio of the pulsed optical signal described above, and the error correction capability of the FEC on the second communication link is detected again until the first ONU 11 gives the first OLT 14 The crosstalk caused by the transmitted pulsed optical signal to the second communication link, and the resulting error rate is within the error range specified by the WDM PON system to determine the optimal duty cycle of the pulsed optical signal, which is optimal. The duty cycle is the first duty cycle.

The determination of the optimum duty cycle of the pulsed optical signal described above is also related to the isolation between the AWG channels. The isolation between the AWG channels is used to measure the AWG's ability to isolate the optical signals of each channel.

For example, when the first AWG 13 and the second AWG 16 have a channel isolation of 25 dB, for a pulsed optical signal with a modulation rate of 10 G Bit/s and a sequence period of 204 ns, the pulse width is used in one cycle. It can be 1 byte wide (eg, 0.8 ns), 2 byte width (1.6 ns), 3 byte width (2.4 ns), and 4 byte width (3.2 ns). Therefore, the duty ratio of the pulsed optical signal can be 1/255, 2/255-2, 3/255-3, and 4/255-4.

When the first AWG 13 and the second AWG 16 have a channel isolation of 20 dB, the same is true for a pulsed optical signal with a modulation rate of 10 G Bit/s and a sequence period of 204 ns, because the isolation between the AWG channels is reduced by 5 dB. In one cycle, the pulse width used is up to 3 bytes wide (2.4 ns), when the pulse width is 1 byte width (for example, 0.8 ns), 2 bytes width (1.6 ns), and 3 The duty cycle of the pulsed optical signal can be 1/255, 2/255-2, and 3/255-3 at a byte width (2.4 ns).

The wavelength locking method provided by the embodiment of the invention determines the optimal lower limit and upper limit of the duty ratio of the pulsed optical signal scanned and transmitted by the first ONU, and determines the optimal pulse optical signal in the lower limit and the upper limit range. The space ratio makes it easier to determine the target wavelength of the first ONU on the premise that the error correction capability of the FEC on the second communication link meets the requirements.

FIG. 3 is a schematic flowchart diagram of Embodiment 2 of a wavelength locking method according to an embodiment of the present invention. The second embodiment of the present invention further illustrates the wavelength locking method based on the first embodiment. Embodiment 2 of the present invention will be described in conjunction with the WDM PON system shown in FIG. 1. As shown in FIG. 3, the wavelength locking method provided by the second embodiment of the present invention further includes:

Step 301: The first OLT 14 receives and acquires pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU 11 one by one and their corresponding optical powers.

Since the value of the first duty ratio that satisfies the requirements may be multiple, the first ONU 11 may scan and transmit the pulsed optical signals of all wavelengths supported by the WDM PON system one by one at different duty ratios respectively, correspondingly, The first OLT 14 receives the pulsed optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU 11 respectively under different duty cycles to obtain the pulsed optical signals of each wavelength and their corresponding optical powers.

Step 302: Select, according to the detection performance and power resolution accuracy of the first OLT 14, the pulse optical signal corresponding to the maximum optical power among the optical powers of all the received pulsed optical signals that the first OLT 14 can detect and can resolve. The duty cycle value is the first threshold.

The first threshold is related not only to the detection performance and power resolution accuracy of the first OLT 14, but also to the length of the first communication link between the first ONU 11 and the first OLT 14. Specifically, for the first communication link of the same distance and the pulsed optical signal of the same duty ratio, in all the received pulsed optical signals detected and identifiable by the first OLT 14, if the optical power is larger, indicating that The better the detection performance and power resolution accuracy of an OLT 14, but for the same first OLT 14 and the same duty cycle pulsed optical signal, if the first ONU 11 and the first OLT 14 are in the first communication link The distance is long, and the energy consumption of the pulsed optical signal during transmission is large. Therefore, the specific value of the first threshold may be set according to the distance between the first ONU and the first OLT, and the detection performance and power resolution accuracy of the first OLT. This is limited.

The wavelength locking method provided by the second embodiment of the present invention determines the size of the first threshold according to the detection performance and the power resolution accuracy of the first OLT, and causes the duty ratio of the pulsed optical signal emitted by the first ONU to be greater than the first threshold. It is ensured that the first OLT receives and acquires the pulsed optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one and their corresponding optical powers.

Further, in the wavelength locking method provided by the first embodiment and the second embodiment of the present invention, when the second communication link is encoded by the FEC RS (255, 239), the value of the first duty ratio is 3/255. -3, Or 4/255-4.

The pulsed optical signal can be determined through multiple experiments according to the detection performance and power resolution accuracy of the first OLT 14 and the error correction capability of the RS (255, 239) encoding of the FEC used by both the first communication link and the second communication link. The optimal duty cycle is 3/255-3, or 4/255-4, that is, the value of the first duty cycle is 3/255-3, or 4/255-4.

In the wavelength locking method provided by the second embodiment of the present invention, when the value of the first duty ratio is 3/255-3 or 4/255-4, the first OLT can not only easily detect the WDM scanned and transmitted by the first ONU. The error rate of the pulsed optical signal of all wavelengths supported by the PON system and the error of the RS (255,239) code of the FEC used on the second communication link is within the error range specified by the WDM PON system.

FIG. 4 is a schematic flowchart diagram of Embodiment 3 of a wavelength locking method according to an embodiment of the present invention. The wavelength locking method provided in the third embodiment of the present invention is described by using the terminal side ONU as a main body. As shown in FIG. 4, the wavelength locking method provided in the embodiment of the present invention is applied to the WDM PON system shown in FIG. 1. As shown in FIG. 4, the wavelength locking method includes:

Step 401: The first ONU 11 scans and transmits the pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT 14 one by one.

The duty ratio of the pulsed optical signals of all wavelengths is a first duty ratio, and the first duty ratio is determined according to an error correction capability of the second communication link.

After determining that the duty ratio of the pulsed optical signal is the first duty ratio, the first ONU 11 located on the terminal side of the WDM PON system scans and transmits the pulsed light of all wavelengths supported by the WDM PON system one by one in a certain order. The signal is sent to the first OLT 14.

Step 402: The first ONU 11 adjusts its own wavelength to the target wavelength according to the target wavelength determined by the first OLT 14.

The target wavelength is determined by the optical power of the pulse optical signals of all wavelengths of the first duty ratio scanned and transmitted by the first ONU 11 according to the first ONU 11.

Specifically, after the first OLT 14 acquires pulse optical signals of all wavelengths of the first duty ratio scanned and transmitted by the first ONU 11 one by one, determining the maximum optical power from the optical powers of the pulse optical signals of all wavelengths. The wavelength emitted by the first ONU 11 is taken as the target wavelength of the first ONU 11.

Step 403: The first ONU 11 communicates with the first OLT 14 according to the target wavelength.

The first ONU 11 can communicate with the first OLT 14 by the target wavelength. When the first ONU 11 is in normal communication with the corresponding first OLT 14, the first ONU 11 can implement communication with the first OLT 14 by a continuous wave signal having a wavelength of the target wavelength and carrying data information to be transmitted.

In the wavelength locking method provided by the third embodiment of the present invention, the pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU are respectively sent to the first OLT, and the first ONU may be according to the first The target wavelength determined by the OLT adjusts the wavelength of the self to the target wavelength, thereby enabling the first ONU to communicate with the first OLT through the target wavelength, since the duty ratios of the pulsed optical signals of all the wavelengths are the first duty ratio And the first duty ratio is determined according to the error correction capability of the second communication link. Therefore, by using the wavelength locking method provided by the third embodiment of the present invention, the first ONU does not go to the adjacent second when the new ONU is newly online. The communication link generates crosstalk, which solves the crosstalk problem caused by the continuous optical signal transmitted by the new ONU in the wavelength adjustment process to the communication link originally in the normal communication state in the existing wavelength locking method, and improves the WDM-PON system. Communication quality.

Further, in the wavelength locking method provided in the foregoing embodiment, when the second communication link uses the RS (255, 239) encoding of the FEC, the ratio of the first duty ratio is less than or equal to (255-239)/(255). -(255-239)).

Due to the RS (255, 239) encoding of FEC, that is, the FEC algorithm can accommodate up to (255-239) bytes of error, the ratio of the first duty cycle must be less than or equal to the upper limit of error correction. That is, the ratio of the first duty ratio is less than or equal to (255-239) / (255 - (255 - 239)).

The ratio of the first duty ratio is greater than or equal to a first threshold, the first threshold being determined according to the detection performance and power resolution accuracy of the first OLT.

FIG. 5 is a schematic flowchart diagram of Embodiment 4 of a wavelength locking method according to an embodiment of the present invention. The fourth embodiment of the present invention further illustrates the wavelength locking method based on the third embodiment. Embodiment 4 of the present invention will be described in conjunction with the WDM PON system shown in FIG. 1. As shown in FIG. 5, the wavelength locking method provided by the embodiment of the present invention further includes:

Step 501: The first ONU 11 scans and transmits the pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT 14 one by one, so that the first OLT 14 is based on the detection performance and power resolution accuracy of the first OLT 14 at the first OLT. The optical power of all the pulsed optical signals that can be detected and can be resolved, the duty value of the pulsed optical signal corresponding to the maximum optical power is selected as a first threshold;

The first OLT 14 takes the duty value of the pulsed optical signal corresponding to the maximum optical power of all received pulsed light signals that it can detect and can resolve as the first threshold. The first threshold reflects the detection performance and power resolution accuracy of the first OLT 14.

Step 502: The first ONU 11 receives the first threshold determined by the first OLT 14.

After receiving the first threshold determined by the first OLT 14, the first ONU 11 determines the first duty ratio in conjunction with the error correction capability of the RS (255, 239) encoding of the FEC on the second communication link.

Further, in the wavelength locking method provided by the fourth embodiment and the fifth embodiment of the present invention, when the second communication link is encoded by the FEC RS (255, 239), the value of the first duty ratio is 3/255. -3, or 4/255-4.

FIG. 6 is a schematic flowchart of Embodiment 1 of a network device according to an embodiment of the present disclosure. The network device provided in the first embodiment of the present invention is located on the central office side of the WDM PON. The embodiment of the present invention is described by taking the WDM PON system shown in FIG. 1 as an example. As shown in FIG. 6, the network device provided by the embodiment of the present invention is a first OLT 14, and the network device includes:

The first transceiver 601 is configured to receive pulsed optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU 11 one by one.

The obtaining unit 602 is configured to obtain optical power of the pulsed optical signals of all wavelengths according to the pulsed optical signals of all wavelengths;

The processor 603 is configured to determine, in the optical power of the pulsed optical signals of all wavelengths, that the wavelength of the first ONU corresponding to the maximum optical power is the target wavelength of the first ONU 11, so that the first ONU 11 is based on the target wavelength. The first OLT 14 communicates.

Further, in the network device provided in the foregoing Embodiment 1, when the second communication link adopts the RS (255, 239) encoding of the FEC, the ratio of the first duty ratio is less than or equal to (255-239)/(255) - (255-239)), and the ratio of the first duty ratio is greater than or equal to a first threshold, the first threshold being determined according to the detection performance and power resolution accuracy of the network device.

Optionally, in the network device provided in the foregoing embodiment, the first transceiver 601 is further configured to receive and acquire pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU 11 and corresponding to each other. Optical power

The obtaining unit 602 is further configured to obtain, according to the detection performance and power resolution accuracy of the network device, Among the optical powers of all the received pulsed light signals that can be detected and can be resolved, the duty ratio of the pulsed optical signals corresponding to the maximum optical power is selected as a first threshold.

Optionally, in the network device provided by the foregoing embodiment, when the second communication link uses the RS (255, 239) encoding of the FEC, the value of the first duty ratio is 3/255-3, Or 4/255-4.

The network device provided in this embodiment may be used to implement the technical solution of the embodiment of the wavelength locking method shown in FIG. 2 and FIG. 3, and the implementation principle and technical effects are similar, and details are not described herein again.

FIG. 7 is a schematic flowchart of Embodiment 2 of a network device according to an embodiment of the present disclosure. The network device provided in the second embodiment of the present invention is located on the terminal side of the WDM PON. The embodiment of the present invention is described by taking the WDM PON system shown in FIG. 1 as an example. As shown in FIG. 7, the network device provided by the embodiment of the present invention is a first ONU 11, and the network device includes:

a second transceiver 701, for scanning and transmitting pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT 14;

The duty ratio of the pulsed optical signals of all wavelengths is a first duty ratio, and the first duty ratio is determined according to an error correction capability of the second communication link;

The wavelength adjustment unit 702 is configured to adjust the self wavelength to the target wavelength according to the target wavelength determined by the first OLT 14.

Wherein, the target wavelength is determined by the optical power of the pulse optical signals of all wavelengths of the first duty ratio scanned and transmitted by the first ONU 11 according to the first ONU 11;

The second transceiver 701 is further configured to communicate with the first OLT 14 according to the target wavelength.

Further, in the network device provided in the foregoing Embodiment 2, when the second communication link adopts the RS (255, 239) encoding of the FEC, the ratio of the first duty ratio is less than or equal to (255-239). ) / (255-(255-239)). The ratio of the first duty ratio is greater than or equal to a first threshold, the first threshold being determined according to the detection performance and power resolution accuracy of the first OLT.

Optionally, in the network device provided by the foregoing embodiment, the second transceiver 701 is further configured to scan and transmit the pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT 14 one by one, so that the first OLT 14 is configured according to the first OLT 14 The detection performance and the power resolution accuracy of the first OLT 14 are selected from the optical power of all the received pulsed light signals that the first OLT 14 can detect and can discriminate, and the duty value of the pulsed optical signal corresponding to the maximum optical power is selected. The first threshold is used to receive the first threshold determined by the first OLT 14.

Optionally, in the network device provided by the foregoing embodiment, when the second communication link adopts FEC When the RS (255, 239) is encoded, the value of the first duty ratio is 3/255-3, or 4/255-4.

The network device provided in this embodiment may be used to implement the technical solution of the embodiment of the wavelength locking method shown in FIG. 4 and FIG. 5 , and the implementation principle and technical effects are similar, and details are not described herein again.

FIG. 8 is a schematic structural diagram of Embodiment 1 of a WDM-PON system according to an embodiment of the present invention. As shown in FIG. 8, the WDM-PON system provided in Embodiment 1 of the present invention includes: at least two ONUs and at least two OLTs. The embodiments of the present invention are described by taking two examples as examples. The first ONU 81 is a new ONU, the second ONU 82 is an ONU, and the first ONU 81 is connected to the first OLT 84 through a first communication link, and between the second ONU 82 and the second OLT 85. Connected via a second communication link.

Specifically, the WDM-PON system also includes two identical AWGs (eg, a first AWG 83 and a second AWG 86). A first communication link connection is established between the first ONU 81 and the first OLT 84 via the first AWG 83 and the second AWG 86. The first ONU 81 is connected to the branching port of the first AWG 83, the first OLT 84 is connected to the branching port of the second AWG 86, and the combining port of the first AWG 83 and the second AWG 86 is connected by the optical fiber 87.

The second OLT 85 is configured to: when determining that the error of the pulsed optical signal to the second communication link can be corrected by the RS (255, 239) encoding of the FEC of the second communication link, and the error rate is less than the WDM PON system specification At the bit error rate, the value of the duty ratio employed by the first ONU 81 at this time is set to the value of the first duty ratio.

The first ONU 81 adopts the network device provided in the embodiment shown in FIG. 6, and can be used to implement the technical solution of the embodiment of the wavelength locking method shown in FIG. 2 and FIG. 3. The first OLT 84 adopts the network provided by the embodiment shown in FIG. The device can be used to implement the technical solution of the wavelength locking method embodiment shown in FIG. 4 and FIG. 5 . The specific structure, implementation principle and technical effects of the first ONU 81 and the first OLT 84 can be implemented as shown in FIG. 6 and FIG. 7 . The network devices provided in the example are not described here.

Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that Modifications may be made to the technical solutions described in the foregoing embodiments, or some or all of the technical features may be equivalently replaced. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

A wavelength locking method, the method is applied in a WDM PON system of a wavelength division multiplexing passive optical network, where the WDM PON comprises: at least two ONUs and at least two OLTs, the first ONU is a new ONU, and the second The ONU is an online ONU, the first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link, wherein the Methods include:

The first OLT receives pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one; wherein the duty ratios of the pulse optical signals of all wavelengths are the first duty Comparing, the first duty ratio is determined according to an error correction capability of the second communication link;

Obtaining, by the first OLT, optical power of the pulsed optical signals of all wavelengths according to the pulsed optical signals of all wavelengths;

Determining, by the optical power of the pulsed optical signals of all the wavelengths, a wavelength emitted by the first ONU corresponding to the maximum optical power is a target wavelength of the first ONU, so that the first ONU is based on the target wavelength The first OLT communicates.
The wavelength locking method according to claim 1, wherein the first duty ratio is determined according to an error correction capability of the second communication link, and specifically includes:

When the first ONU scans and transmits a pulsed optical signal of any duty ratio to the first OLT one by one, the second OLT detects the pulsed optical signal on the second communication link;

If the second OLT determines that the error of the pulsed optical signal to the second communication link can be encoded by the Reed-Solomon RS (255, 239) of the forward error correction FEC of the second communication link Corrected, and the error rate is less than the error rate specified by the WDM PON system, and the value of the duty ratio adopted by the first ONU at this time is set to the value of the first duty ratio;

The ratio of the any one of the duty ratios is less than or equal to (255-239) / (255 - (255 - 239)), and is greater than or equal to the first threshold, the first threshold is according to the first OLT Detection performance and power resolution accuracy are determined.
The wavelength locking method according to claim 2, wherein the method further comprises:

The first OLT receives and acquires pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one and their corresponding optical powers;

Selecting a maximum optical power among optical powers of all received pulsed optical signals that the first OLT can detect and can distinguish according to the detection performance and power resolution accuracy of the first OLT The duty ratio of the corresponding pulsed optical signal is a first threshold.
The wavelength locking method according to any one of claims 1 to 3, wherein when said second communication link is encoded by Reed-Solomon RS (255, 239) of forward error correction FEC, The value of the first duty cycle is 3/255-3, or 4/255-4.
A wavelength locking method, the method is applied in a wavelength division multiplexing passive optical network (WDM PON), the WDM PON includes: at least two ONUs and at least two OLTs, the first ONU is a new uplink ONU, and the second ONU The first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link, wherein the method is include:

The first ONU scans and transmits the pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT one by one; wherein the duty ratios of the pulsed optical signals of all wavelengths are the first duty ratio, Determining a first duty cycle according to an error correction capability of the second communication link;

The first ONU adjusts its own wavelength to the target wavelength according to the target wavelength determined by the first OLT, wherein the target wavelength is the first scanning and transmitting by the first OLT according to the first ONU. Determining the optical power of a pulsed optical signal of all wavelengths of a duty cycle;

The first ONU communicates with the first OLT according to the target wavelength.
The wavelength locking method according to claim 5, wherein said first duty ratio is when said second communication link is encoded by Reed-Solomon RS (255, 239) of forward error correction FEC The ratio is less than or equal to (255-239) / (255 - (255 - 239)).
The wavelength locking method according to claim 5, wherein the ratio of the first duty ratio is greater than or equal to a first threshold, and the first threshold is determined according to a detection performance and a power resolution accuracy of the first OLT .
The wavelength locking method according to claim 7, wherein the method further comprises:

The first ONU scans and transmits the pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT one by one, so that the first OLT is based on the detection performance and power resolution precision of the first OLT. The optical power of all the received pulsed optical signals that the first OLT is capable of detecting and capable of distinguishing, the duty ratio of the pulsed optical signal corresponding to the selected maximum optical power is a first threshold;

The first ONU receives the first threshold determined by the first OLT.
A wavelength locking method according to any one of claims 5-8, wherein when said When the second communication link is encoded by Reed-Solomon RS (255, 239) of forward error correction FEC, the value of the first duty ratio is 3/255-3, or 4/255-4.
A network device, the network device is located at a central office side of a WDM PON of a wavelength division multiplexing passive optical network, where the WDM PON includes: at least two ONUs and at least two OLTs, and the first ONU is a new ONU, The second ONU is connected to the ONU, and the first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link. The network device is the first OLT, and includes:

a first transceiver, configured to receive pulse optical signals of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one; wherein a duty ratio of the pulse optical signals of all wavelengths is first a duty ratio, the first duty ratio being determined according to an error correction capability of the second communication link;

An acquiring unit, configured to obtain optical powers of the pulsed optical signals of all the wavelengths according to the pulsed optical signals of all the wavelengths;

a processor, configured to determine, in an optical power of the pulsed optical signals of all the wavelengths, a wavelength emitted by the first ONU corresponding to the maximum optical power as a target wavelength of the first ONU, so that the first ONU is configured according to the The target wavelength is in communication with the first OLT.
The network device according to claim 10, wherein when said second communication link is encoded by Reed-Solomon RS (255, 239) of forward error correction FEC, said first duty cycle The ratio is less than or equal to (255-239) / (255 - (255 - 239)).
The network device according to claim 10, wherein the ratio of the first duty ratio is greater than or equal to a first threshold, and the first threshold is determined according to a detection performance and a power resolution accuracy of the network device.
The network device according to claim 12, wherein the first transceiver is further configured to receive and acquire pulse light of all wavelengths supported by the WDM PON system scanned and transmitted by the first ONU one by one. Signal and its corresponding optical power;

The acquiring unit is further configured to: according to the detection performance and the power resolution precision of the network device, select, according to the optical power of all the received pulse optical signals that the acquiring unit can detect and can distinguish, the maximum optical power is selected. The duty cycle value of the pulsed optical signal is a first threshold.
The network device according to any one of claims 10-13, wherein when the second communication link is encoded by Reed-Solomon RS (255, 239) of forward error correction FEC, The value of the first duty cycle is 3/255-3, or 4/255-4.
A network device, the network device is located at a terminal side of a WDM PON of a wavelength division multiplexing passive optical network, where the WDM PON includes: at least two ONUs and at least two OLTs, the first ONU is a new ONU, and the second The ONU is an online ONU, the first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link, wherein the The network device is the first ONU, including:

a second transceiver, configured to scan and transmit pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT one by one; wherein a duty ratio of the pulse optical signals of all wavelengths is first a ratio of the first duty ratio determined according to an error correction capability of the second communication link;

a wavelength adjustment unit, configured to adjust a self wavelength to the target wavelength according to the target wavelength determined by the first OLT, wherein the target wavelength is that the first OLT scans and transmits one by one according to the first ONU The optical power of the pulsed optical signals of all wavelengths of the first duty cycle is determined;

The second transceiver is further configured to communicate with the first OLT according to the target wavelength.
The network device according to claim 15, wherein when said second communication link is encoded by Reed-Solomon RS (255, 239) of forward error correction FEC, said first duty cycle The ratio is less than or equal to (255-239) / (255 - (255 - 239)).
The network device according to claim 15, wherein the ratio of the first duty ratio is greater than or equal to a first threshold, and the first threshold is determined according to a detection performance and a power resolution accuracy of the first OLT.
The network device according to claim 17, wherein the second transceiver is further configured to scan and transmit pulsed optical signals of all wavelengths supported by the WDM PON system to the first OLT one by one, so that The first OLT selects a pulse corresponding to the maximum optical power among the optical powers of all the received pulsed optical signals that the first OLT can detect and can distinguish according to the detection performance and the power resolution accuracy of the first OLT. The duty ratio of the optical signal is a first threshold for receiving the first threshold determined by the first OLT.
The network device according to any one of claims 15 to 18, wherein when said second communication link is encoded by Reed-Solomon RS (255, 239) of forward error correction FEC, said The value of a duty cycle is 3/255-3, or 4/255-4.
A wavelength division multiplexing passive optical network WDM PON system, the WDM PON system includes: at least two ONUs and at least two OLTs, the first ONU is a new uplink ONU, and the second ONU The first ONU is connected to the first OLT through a first communication link, and the second ONU is connected to the second OLT through a second communication link, wherein the An OLT is the network device of any one of claims 10 to 14, the first ONU being the network device of any one of claims 15-19.