Downstream signal synchronization method and system

Abstract

The present disclosure relates to a downstream signal synchronization method and system, and relates to the field of passive optical networks. The method is applicable to a wavelength division multiplexing passive optical network. Specifically, when an optical network unit (ONU) is in an operating state, it can detect whether a situation where the synchronization of the downstream signal is lost has occurred. The downstream signal includes a management path signal and a data path signal. When a situation occurs where the synchronization of the management path signal is lost and the data path signal is normally synchronized, the ONU switches from the operating state to a management path synchronization loss sub-state, monitors a first recovery time for the ONU to recover the synchronization of the management path signal in the management path synchronization loss sub-state. If the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization loss sub-state to the operating state. In this way, it is possible to avoid the problem that the ONU goes out of management due to the absence of a state transition method in the situation corresponding to the original state machine.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to a Chinese patent application bearing application number 202210498932.8, filed on May 9, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] TECHNICAL FIELD The embodiments of the present disclosure relate to the field of passive optical network technology, and more particularly to a downstream signal synchronization method and system. [Background technology]

[0003] High-speed passive optical network (PON) technology, which is widely deployed and applied in existing networks, mainly uses time-division multiplexed EPON (Ethernet Passive Optical Network) or GPON (Gigabit-Capable PON) systems, with the uplink and downlink operating on a single wavelength and transmitting via a mechanism that allocates transmission time for each. Wavelength Division Multiplexing Passive Optical Networks (WDM-PONs) use wavelength division multiplexing (WDM) technology, with the PON port of the central office optical line terminal (OLT) and the optical network unit (ONU) on the user side each monopolizing a pair of wavelength paths in a point-to-point manner. This allows for access to several times more users than conventional time division PONs, and primarily provides network connections for government and enterprise users, wireless bearers, etc. WDM-PONs can save core optical fiber resources, particularly in the 5G fronthaul field, and reduce the costs and difficulty of network implementation, maintenance, and operation.

[0004] In conventional PONs, the ONU registration and activation process involves states such as distance measurement and time slot allocation due to the characteristics of time division multiplexing, but these states are not required in WDM-PONs based on wavelength division multiplexing. Currently, in existing WDM-PON systems, the basic framework of the ONU registration and activation process remains the same as in conventional PONs. When the ONU startup state machine is in the operating state, the state machine specifies a state transition method only for situations where data path synchronization is lost.

[0005] It should be noted that the information disclosed in the above background section is merely intended to enhance understanding of the background of the present disclosure and may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] According to one aspect of the present disclosure, there is provided a downstream signal synchronization method applied to a wavelength division multiplexing passive optical network, the method comprising: The detection module When the optical network unit ONU is in an operational state, detecting whether a situation occurs in which a synchronization of a downstream signal is lost, and the downstream signal includes a management path signal and a data path signal; When a situation occurs in which the synchronization of the management path signal is lost and the data path signal is normally synchronized, the ONU switches from the working state to a management path synchronization loss sub-state; The first monitoring module Monitoring a first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization loss substate; If the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization loss sub-state to the operating state, thereby allowing the ONU to continue operating in the operating state.

[0007] In some embodiments, the method includes, after monitoring a first recovery time during which the ONU regains synchronization of the management path signal in the management path synchronization loss substate, The method further includes the ONU switching from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state when a situation occurs in which the data path signal synchronization is lost within the first predetermined time threshold.

[0008] In some embodiments, the method includes, after monitoring a first recovery time during which the ONU regains synchronization of the management path signal in the management path synchronization loss substate, The ONU further includes switching from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state if the first recovery time exceeds the first predetermined time threshold.

[0009] In some embodiments, the method further comprises: The second monitoring module monitoring a second recovery time of the management path signal and the data path signal of the ONU in the temporary LODS state; If the second recovery time does not exceed a second predetermined time threshold, returning the ONU to the operating state and continuing operation; The method further includes: if the second recovery time exceeds the second predetermined time threshold, the ONU enters an initial state of downstream signal synchronization.

[0010] In some embodiments, in the management path synchronization loss sub-state, the data path signals of the ONU are synchronized and operate normally.

[0011] According to one aspect of the present disclosure, there is provided a downstream signal synchronization system applied to a wavelength division multiplexing passive optical network, the system comprising: a detection module, which is used to detect whether a synchronization loss situation occurs in downstream signals when the optical network unit ONU is in operation, the downstream signals including a management path signal and a data path signal; a first switching module, which is used to switch the ONU from the working state to a management path synchronization loss sub-state when the synchronization of the management path signal is lost and the data path signal is normally synchronized; a first monitoring module, used for monitoring a first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization loss substate; a first return module for returning the ONU from the management path synchronization loss sub-state to the operating state if the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, so that the ONU continues to operate in the operating state.

[0012] In some embodiments, the system comprises: When a situation occurs in which the data path signal synchronization is lost within the first predetermined time threshold, the ONU further includes a second switching module used to switch from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state.

[0013] In some embodiments, the system comprises: The ONU further includes a second switching module used for switching from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state when the first recovery time exceeds the first predetermined time threshold.

[0014] In some embodiments, the system comprises: The ONU further includes a second monitoring module used to monitor a second recovery time for the ONU to recover the management path signal and the data path signal in the temporary LODS state, and if the second recovery time does not exceed a second predetermined time threshold, the ONU returns to the operating state and continues operating, and if the second recovery time exceeds the second predetermined time threshold, the ONU enters the initial state of the downstream signal synchronization.

[0015] In some embodiments, in the management path synchronization lost sub-state, the data path signals of the ONU are synchronized and operate normally.

[0016] According to one aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored therein, the computer program being capable of realizing the downlink signal synchronization method described in any one of the above claims when executed by a processor.

[0017] It should be noted that the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the present disclosure. [Brief explanation of the drawings]

[0018] The drawings herein are incorporated into the specification and constitute a part of this specification, illustrate embodiments consistent with the present disclosure, and are used together with the specification to interpret the principles of the present disclosure. Obviously, the drawings in the following description are merely some embodiments of the present disclosure, and those skilled in the art can obtain other drawings based on these drawings without creative efforts. [Figure 1] FIG. 1 is an ONU registration activation process of a wavelength division multiplexing passive optical network system in the related art. [Figure 2] FIG. 2 is a step flowchart of a downstream signal synchronization method according to some embodiments of the present disclosure. [Figure 3] FIG. 3 is a flowchart of ONU synchronization recovery according to some embodiments of the present disclosure. [Figure 4] FIG. 4 is a block diagram of a downstream signal synchronization system according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] Exemplary embodiments will now be described more completely with reference to the accompanying drawings. However, exemplary embodiments may be embodied in many forms and should not be construed as limited to the examples set forth herein. Rather, providing these embodiments will make the present disclosure more thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of the embodiments of the present disclosure. However, as will be understood by those skilled in the art, the technical solutions of the present disclosure may be implemented by omitting one or more of the specific details, or by using other methods, components, devices, steps, etc. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring aspects of the present disclosure.

[0020] It should be noted that the drawings are merely schematic diagrams of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings indicate the same or similar parts, and therefore, redundant description will be omitted. Some block diagrams shown in the drawings are functional entities that do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in the form of software, in one or more hardware modules or integrated circuits, or in different networks and / or processor and / or microcontroller devices.

[0021] In a wavelength division multiplexing passive optical network (WDM-PON), a user data path and a management client path (management TC data path) are separated in the transmission pooling layer and pass through the transmission pooling layer (TC), where user data is not processed by the TC layer, and management data is processed by the TC layer in a specific manner, and the transmission manner is divided into two modes: transcoded transmission and transparent transmission. Therefore, in the ONU registration and activation process of a wavelength division multiplexing passive optical network (WDM-PON), the embodiment of the present disclosure mainly includes an initial state, a serial number state, an operation state, and an intermittent data path synchronization loss state.

[0022] In the initial state (O1), the ONU enters the initial state (O1) when it is first powered on or rebooted. During the initial state (O1), the ONU can turn on its receiver and turn off its transmitter. The initial state (O1) may further include an off-sync substate (O1.1) and a profile learning substate (O1.2). The off-sync substate (O1.1) may be an entry of the initial state (O1) and may be entered when the ONU attempts to synchronize with a PON wavelength path. The profile learning substate (O1.2) may be used by the ONU to determine whether a wavelength path is available by obtaining profile information via a downstream PLOAM message. If it is determined that downstream synchronization of the wavelength path is successful, the ONU can enter the profile learning substate (O1.2).

[0023] The serial number state (O2-3) may be an ONU-initiated transmitter. The serial number state (O2-3) may be used by the ONU to periodically transmit specific PLOAM (physical layer operations, administration and maintenance) messages to provide authentication information until the OLTCT confirms the assignment of the ONU-ID. When the time the ONU spends in the serial number state (O2-3) times out, the ONU can return from the serial number state (O2-3) to the initial state (O1).

[0024] The operating state (O5) may be used by an ONU to transmit and receive signals through a PON path. In some embodiments of the present disclosure, the operating state (O5) may further include a loss of downstream synchronization in the management TC data path (MLODS) substate (which may also be referred to as O5.1 or O5.3). Specifically, when an ONU in the operating state (O5) experiences a situation where the synchronization of the data path signal is normal but the synchronization of the management path signal is lost, the ONU can enter the loss of downstream synchronization in the management TC data path substate (O5.3). After entering the management path synchronization lost substate (O5.3), the ONU can start timer TO1 (which may also be called TOM), which records the time the ONU is in the management path synchronization lost substate (O5.3). If the ONU regains synchronization of the management path signal before TO1 times out, the ONU returns to the operating state (O5); if TO1 times out, the ONU stops data transmission and enters the temporary data path synchronization lost state (IntermittentLODS state, O6).

[0025] The temporary data path synchronization loss state (O6) may be entered after the operating state (O5), i.e., when an ONU in the operating state (O5) loses synchronization of the data path signal or the time in the management path synchronization loss state (O5.3) times out, and the temporary data path synchronization loss state (O6) may be abbreviated as the temporary LODS state.

[0026] Specifically, after an ONU is accessed and powered on, it enters the initial state (O1) and begins ONU activation. That is, the ONU tunes its receiver, searches for the wavelength of the downstream path, synchronizes with the data and management paths, collects profile information, and performs operations such as verifying basic parameters. After the ONU determines the wavelength of the downstream path, the ONU tunes its transmitter and declares its presence via a specific message for authentication. After the OLTCT successfully authenticates the ONU, it confirms via a specific message, and the ONU enters the operating state (O5). If an ONU in the operating state (O5) loses downstream synchronization of the data path, the ONU temporarily enters the LODS state (O6). In the temporary LODS state (O6), it can detect whether the time required to restore synchronization of the data path signal and the management path signal is less than a preset threshold. If the required time is less than the preset threshold, i.e., if the ONU successfully restores synchronization of the data path signal and the management path signal within the preset threshold, the ONU can return to the operating state (O5). If the required time is greater than the preset threshold, i.e., if the ONU does not successfully restore synchronization of the data path signal and the management path signal within the preset threshold, the ONU can return to the asynchronous substate (O1.1) of the initial state (O1) and restart. If an ONU in the operating state (O5) loses synchronization of the management path but the data path is still transmitting and receiving normally, the ONU may fall out of management because there is no corresponding state transition method in the related art.

[0027] Figure 1 shows the ONU registration and activation process for a wavelength division multiplexing passive optical network (WDM) in the related art. As shown in Figure 1, 01, an ONU in the asynchronous substate (O1.1) enters the profile learning substate (O1.2) when the downstream signal regains synchronization (DSYNC), i.e., both the data path signal and the management path signal regain synchronization. 02, an ONU in the profile learning substate (O1.2) enters the asynchronous substate (O1.1) when data path synchronization is lost (LODS) or the downstream wavelength path (DWLCH) is incompatible. 03, an ONU in the initial state (O1) enters the serial number state (O2-3) when the downstream wavelength path (DWLCH) can operate normally. 04, an ONU in the serial number state (O2-3) enters the operational state (O5) when an ONU-ID assignment is performed. 05. An ONU in the operating state (O5) enters the temporary LODS state (O6) when a loss of downstream synchronization (LODS) occurs. 06. An ONU in the temporary LODS state (O6) enters the temporary LODS state (O6) when the downstream signal regains synchronization (DSYNC), i.e., both the data path signal and the management path signal regain synchronization. 07. An ONU in the serial number state (O2-3) enters the asynchronous substate (O1.1) when a loss of data path synchronization occurs, the serial number state (O2-3) residence time expires, or the ONU-ID request is released. 08. An ONU in the operating state (O5) enters the asynchronous substate (O1.1) when the ONU-ID request is released. 09. An ONU in the temporary LODS state (O6) enters the asynchronous substate (O1.1) when the residence time in the temporary LODS state (O6) expires.

[0028] FIG. 2 is a step flowchart of a downstream signal synchronization method according to an embodiment of the present disclosure, which is applied to a wavelength division multiplexing passive optical network. As shown in FIG. 2, the method may include steps S101 to S104.

[0029] In step S101, when the optical network unit ONU is in an operational state, it detects whether a situation occurs in which the synchronization of the downstream signal is lost, and the downstream signal includes a management path (managementTC data path) signal and a data path (datapath) signal.

[0030] In some embodiments of the present disclosure, the optical network unit ONU enters an operating state during the ONU registration activation process. When in the operating state, the optical network unit ONU needs to synchronize its downstream signal. During the synchronization process, the management path signal may lose synchronization, the data path signal may lose synchronization, or both the management path signal and the data path signal may lose synchronization. Therefore, by detecting whether the downstream signal has lost synchronization, the problem of signal synchronization loss can be resolved in a timely manner and the problem of the ONU falling out of management due to signal synchronization loss can be avoided.

[0031] In step S102, if a situation occurs in which the synchronization of the management path signal is lost and the data path signal is normally synchronized, the ONU switches from the working state to a management path synchronization lost sub-state.

[0032] In some embodiments of the present disclosure, if a situation occurs in which the ONU is currently in an operating state and the management path signal synchronization is lost, but the data path signal is normally synchronized, the ONU can enter a management path synchronization lost sub-state from the operating state, which can also be abbreviated as an MLODS sub-state. In the MLODS sub-state, the ONU's data path synchronization is normal, that is, user data can be transmitted and received normally and is not affected by the MLODS sub-state.

[0033] In step S103, in the management path synchronization loss substate, the ONU monitors a first recovery time for recovering synchronization of the management path signal.

[0034] In some embodiments of the present disclosure, when an ONU is in the MLODS substate, the time required to restore synchronization of the management path signal can be recorded, a first recovery time can be obtained, and real-time monitoring can be performed to determine whether the first recovery time exceeds a first predetermined time threshold. The first recovery time can record the time the ONU is in the MLODS substate, and the first predetermined time threshold can be preset according to actual conditions to limit the time the ONU remains in the MLODS substate while attempting to restore synchronization of the management path. This can avoid the problem of the ONU remaining in the management path synchronization loss state for too long, causing the ONU to fall out of management in the MLODS substate. Note that in the MLODS substate, the ONU only loses synchronization of the management path signal, but the synchronization of the data path signal is normal. Therefore, the data path can still operate normally in the MLODS substate, i.e., user data transmission and reception can still operate normally.

[0035] In some embodiments, the ONU turns on a first timer (such as the TOM in the above-described embodiments), where the duration of the first timer is set to a first predetermined time threshold. The ONU determines whether the first timer has timed out when synchronization of the management path signal is restored, thereby determining whether the first recovery time for the ONU to restore synchronization of the management path signal in the management path synchronization lost substate exceeds the first predetermined time threshold.

[0036] In step S104, if the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization loss sub-state to the working state, so that the ONU continues to operate in the working state.

[0037] In some embodiments of the present disclosure, if the first recovery time does not exceed the first predetermined time threshold, i.e., if the management path signal recovers synchronization within the first predetermined time threshold and the data path signal is still synchronized normally, the ONU can be returned from the MLODS sub-state to the operating state, so that the ONU can continue to operate normally in the operating state and perform normal transmission and reception operations for downstream signals.

[0038] As described above, the downstream signal synchronization method provided by the embodiments of the present disclosure is applicable to a wavelength division multiplexing passive optical network, and when an optical network unit (ONU) is in an operational state, it can detect whether a downstream signal synchronization loss occurs. The downstream signal includes a management path signal and a data path signal. When a situation occurs in which the management path signal synchronization is lost but the data path signal is normally synchronized, the ONU switches from the operational state to a management path synchronization lost substate, and monitors a first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization lost substate. If the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization lost substate to an operational state, so that the ONU continues to operate normally in the operational state. In this way, the introduction of a substate in which only the management path synchronization is lost into the operational state compensates for the fact that the conventional ONU registration activation state mechanism does not consider a situation in which the management path signal synchronization is lost, and avoids the problem of the ONU falling out of management due to the lack of a state transition method corresponding to the situation in the original state machine.

[0039] In some embodiments, the method further includes, after monitoring a first recovery time for the ONU to regain synchronization of the management path signal in the management path synchronization loss (MLODS) substate, if a situation occurs in which synchronization of the data path signal is lost within the first predetermined time threshold, the ONU switches from the management path synchronization loss (MLODS) substate to a temporary data path synchronization loss (LODS) state.

[0040] In some embodiments of the present disclosure, when an ONU is in the MLODS substate, it may be that a situation occurs in which the synchronization of the data path signal is lost, that is, a situation in which the synchronization of the data path signal is lost within a first predetermined time threshold. Since the synchronization of both the data path signal and the management path signal of the ONU is lost, the ONU can directly switch to the temporary LODS state and attempt to restore synchronization of the downstream signal.

[0041] In some embodiments, the method further includes, after monitoring a first recovery time for the ONU to regain synchronization of the management path signal in the management path synchronization loss (MLODS) substate, if the first recovery time exceeds the first predetermined time threshold, the ONU switches from the management path synchronization loss (MLODS) substate to a temporary data path synchronization loss (LODS) state.

[0042] In some embodiments of the present disclosure, the first recovery time for recovering synchronization of the management path signal may exceed a first predetermined time threshold, i.e., the management path signal synchronization may not be recovered within the first predetermined time threshold, and the ONU may be returned from the MLODS sub-state to the temporary LODS state, so that the ONU can attempt to recover synchronization of the downstream signal in the temporary LODS state.

[0043] In some embodiments, the above-mentioned downstream signal synchronization method in the embodiments of the present disclosure further includes the steps of: monitoring a second recovery time of the management path signal and the data path signal of the ONU in the temporary LODS state; if the second recovery time does not exceed a second predetermined time threshold, the ONU returning to the operating state and continuing operation; and if the second recovery time exceeds the second predetermined time threshold, the ONU entering the initial state of the downstream signal synchronization.

[0044] In some embodiments of the present disclosure, for an ONU in a temporary LODS state, the time required for the ONU to recover the management path signal and the data path signal may be recorded, a second recovery time may be obtained, the second recovery time may be detected, and whether the second recovery time exceeds a second predetermined time threshold may be determined, where the second recovery time may be the time the ONU is in the temporary LODS state, and the second predetermined time threshold may be the time for restricting the ONU from staying in the LODS state, and the specific value may be specifically set according to actual circumstances.

[0045] In some embodiments, the ONU turns on a second timer (TOL), where the duration of the second timer is set to a second predetermined time threshold, and the ONU determines whether a second recovery time for the ONU to recover the management path signal and the data path signal in the temporary LODS state exceeds a second predetermined time threshold by determining whether the second timer times out when the management path signal and the data path signal are recovered.

[0046] In some embodiments of the present disclosure, if the second recovery time does not exceed the second predetermined time threshold, i.e., if the ONU's management path signal synchronization and data path signal synchronization are both restored to normal within the second predetermined time threshold, the ONU can return from the temporary LODS state to an operating state and continue normal operation.If the second recovery time exceeds the second predetermined time threshold, i.e., if the ONU's management path signal synchronization and data path signal synchronization cannot be restored within the second predetermined time threshold, the ONU can directly enter the initial state of downstream signal synchronization.

[0047] 3 is a flowchart of ONU synchronization recovery provided by an embodiment of the present disclosure. As shown in FIG. 3, 11, when an ONU in the operation state (O5) loses synchronization on the management path but the data path is operating normally, it enters the MLODS substate (O5.3) and attempts to recover synchronization within a certain period of time. During this time, user data transmission and reception is still normal and unaffected. 12, when an ONU in the MLODS substate (O5.3) successfully recovers synchronization on the management path and the data path signal is still operating normally, it returns to the operation state (O5). 13, when an ONU in the MLODS substate (O5.3) loses synchronization on the management path beyond a second predetermined time threshold or loses synchronization on the data path within the second predetermined time threshold, it enters the temporary LODS state (O6) to recover synchronization on the data path. 14. If an ONU in the working state (O5) loses synchronization of the data path, it cannot guarantee normal transmission and reception of user data at this time, so it will enter the temporary LODS state (O6) to recover synchronization of the data path. 15. If the ONU in the temporary LODS state (O6) successfully recovers synchronization of the data path and synchronization of the management path, it will return to the working state (O5).

[0048] [Table 1]

[0049] For example, Table 1 shows events that can be used for state transitions in an embodiment of the present disclosure. When an ONU is in the operating state O5 and a situation in which the synchronization of the management path signal is lost occurs, the first predetermined time threshold is turned on and the ONU switches to the MLODS substate, and the management path synchronization lost state O5.3 and the LODS state O6 do not apply to the MLODS substate. When a management path synchronization recovery (MDSYNC) occurs in the management path synchronization lost state O5.3, the first predetermined time threshold can be turned on and the ONU can switch to the operating state O5, and the operating state O5 and the LODS state O6 do not apply to MDSYNC. When an LODS occurs in the management path synchronization lost state O5.3, that is, a situation in which the synchronization of the data path signal is lost occurs, the second predetermined time threshold can be turned on and the ONU can switch to the LODS state O6, and the LODS state O6 does not apply to LODS. Downstream synchronization recovery (DSYNC) does not apply to the operating state O5 or the management path synchronization loss state O5.3. In the LODS state O6, when DSYNC occurs, the second predetermined time threshold is deactivated and a switch to the operating state O5 can be made. In the management path synchronization loss state O5.3, when the first predetermined time threshold expires, the second predetermined time threshold is activated and a switch to the LODS state O6 can be made. The first predetermined time threshold expires and does not apply to the operating state O5 or the LODS state O6. In the LODS state O6, when the second predetermined time threshold expires, the ONU-ID value is discarded and a switch to the asynchronous state O1.1 (i.e., restart) can be made.

[0050] FIG. 4 is a downstream signal synchronization system according to an embodiment of the present disclosure. As shown in FIG. 4, the system 30 may include a detection module 301, a first switching module 302, a first monitoring module 303, and a first return module 304.

[0051] The detection module 301 is used to detect whether a situation occurs in which the downstream signal loses synchronization when the optical network unit ONU is in operation, and the downstream signal includes a management path signal and a data path signal.

[0052] The first switching module 302 is used to switch the ONU from the working state to a management path synchronization loss sub-state when a situation occurs in which the management path signal synchronization is lost and the data path signal is normally synchronized.

[0053] The first monitoring module 303 is used to monitor a first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization loss substate.

[0054] The first return module 304 returns the ONU from the management path synchronization loss sub-state to the working state if the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, so that the ONU continues to operate in the working state.

[0055] As described above, the downstream signal synchronization system provided by the embodiment of the present invention is applicable to a wavelength division multiplexing passive optical network, and when an optical network unit (ONU) is in an operational state, it can detect whether a downstream signal synchronization loss occurs. The downstream signal includes a management path signal and a data path signal. When a situation occurs in which the management path signal synchronization is lost but the data path signal is normally synchronized, the ONU switches from the operational state to a management path synchronization lost substate, monitors a first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization lost substate, and if the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization lost substate to an operational state, so that the ONU continues to operate normally in the operational state. In this way, the introduction of a substate in which only the management path synchronization is lost into the operational state compensates for the fact that the conventional ONU registration activation state mechanism does not consider a situation in which the management path signal synchronization is lost, and avoids the problem of the ONU falling out of management due to the lack of a state transition method corresponding to the situation in the original state machine.

[0056] In some embodiments, the system 30 further includes a second switching module used to switch the ONU from the management path synchronization loss sub-state to a temporary data path synchronization loss (LODS) state when a situation occurs in which the data path signal synchronization is lost within the first predetermined time threshold.

[0057] In some embodiments, the system 30 further includes a second switching module used to switch the ONU from the management path synchronization loss sub-state to a temporary data path synchronization loss (LODS) state if the first recovery time exceeds the first predetermined time threshold.

[0058] In some embodiments, the system 30 further includes a second monitoring module used to monitor a second recovery time of the management path signal and the data path signal of the ONU in the temporary LODS state, and if the second recovery time does not exceed a second predetermined time threshold, the ONU returns to the operating state and continues operation, and if the second recovery time exceeds the second predetermined time threshold, the ONU enters the initial state of downstream signal synchronization.

[0059] In some embodiments, in the management path synchronization loss sub-state, the data path signal of the ONU is synchronized and operates normally. The specific details of each module in the downstream signal synchronization system are described in detail in the corresponding downstream signal synchronization method, and therefore will not be described here.

[0060] It should be noted that although the above detailed description refers to several modules or units of a device for performing actions, such division is not required. In fact, according to embodiments of the present disclosure, features and functions of two or more of the modules or units described above may be embodied in one module or unit. Conversely, features and functions of one of the modules or units described above may be further divided and embodied in multiple modules or units.

[0061] Furthermore, although the steps of the methods in this disclosure are described in a particular order in the figures, this does not require or imply that the steps must be performed in that particular order, or that all of the steps shown must be performed, to achieve desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into a single step, and / or a single step may be broken down into multiple steps, etc.

[0062] In an exemplary embodiment of the present disclosure, an electronic device capable of implementing the above method is further provided.

[0063] As will be understood by those skilled in the art, each aspect of the present disclosure may be realized as a system, a method, or a program product. Accordingly, each aspect of the present disclosure may be realized in the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, microcode, etc.), or an embodiment combining hardware and software aspects, which may be collectively referred to herein as a "circuit," "module," or "system."

[0064] From the description of the above embodiments, those skilled in the art can easily understand that the exemplary embodiments described herein may be realized by software, or by a combination of software and necessary hardware. Therefore, the technical solutions according to the embodiments of the present disclosure may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (which may be a CD-ROM, a U-disk, a portable hard disk, etc.) or a network, and includes several instructions that cause a computing device (which may be a personal computer, a server, a terminal device, a network device, etc.) to perform the method according to the embodiments of the present disclosure.

[0065] In an exemplary embodiment of the present disclosure, a computer-readable storage medium is further provided having stored thereon a program product capable of implementing the above-described methods of the present disclosure. In some possible embodiments, each aspect of the present disclosure may be implemented in the form of a program product including program code, which, when executed on a terminal device, causes the terminal device to perform steps according to various exemplary embodiments of the present disclosure described in the "Exemplary Method" section above of the present disclosure.

[0066] A program product for implementing the above method according to an embodiment of the present disclosure may be implemented on a portable compact disc read-only memory (CD-ROM), containing program code, and capable of being executed on an end device such as a personal computer. However, the program product of the present disclosure is not limited thereto, and in this specification, a readable storage medium may be any tangible medium that contains or stores a program for use by or in combination with an instruction execution system, apparatus, or device.

[0067] The program product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (non-exhaustive list) of readable storage media include an electrical connection having one or more conductors, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0068] A computer-readable signal medium may include a propagated data signal, in baseband or as part of a carrier, having readable program code carried therein. Such a propagated data signal may take various forms, including, but not limited to, an electromagnetic signal, an optical signal, or any suitable combination of the above. A readable signal medium may be any readable medium other than a readable storage medium, which can transmit, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0069] The program code contained in the readable medium may be transmitted over any suitable medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above.

[0070] Program code for performing the operations of the present disclosure can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, etc., and further including conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may execute entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., connected via the Internet using an Internet Service Provider).

[0071] It should be noted that the above drawings are merely schematic illustrations of the processes included in the method according to the exemplary embodiments of the present disclosure, and are not intended to be limiting. For ease of understanding, the processes shown in the drawings do not indicate or limit the time order of these processes. It is also readily understood that these processes may be performed, for example, synchronously or asynchronously by multiple modules.

[0072] Other embodiments of the present disclosure will be readily apparent to those skilled in the art after considering the specification and practicing the invention(s) invented herein. This application is intended to cover any modifications, uses, or adaptations of the present disclosure, which modifications, uses, or adaptations follow the general principles of the present disclosure and include common general knowledge or ordinary technical means in the art that are not invented in the present disclosure. The specification and examples are exemplary only, with the true scope and spirit of the present disclosure being indicated by the following claims.

Claims

1. A downstream signal synchronization method applied to a wavelength division multiplexing passive optical network, comprising: The detection module detects whether a situation occurs in which a synchronization of a downstream signal is lost when the optical network unit ONU is in an operational state, and the downstream signal includes a management path signal and a data path signal; When a situation occurs in which the synchronization of the management path signal is lost and the data path signal is normally synchronized, the ONU switches from the working state to a management path synchronization loss sub-state; a first monitoring module monitoring a first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization loss substate; If the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, the ONU returns from the management path synchronization loss sub-state to the operating state, thereby allowing the ONU to continue operating in the operating state.

2. The method comprises: After monitoring a first recovery time during which the ONU regains synchronization of the management path signal in the management path synchronization loss substate, 2. The downstream signal synchronization method of claim 1, further comprising: if a situation occurs in which synchronization of the data path signal is lost within the first predetermined time threshold, the ONU switches from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state.

3. The method comprises: After monitoring a first recovery time during which the ONU regains synchronization of the management path signal in the management path synchronization loss substate, 2. The downstream signal synchronization method of claim 1, further comprising: if the first recovery time exceeds the first predetermined time threshold, the ONU switches from the management path synchronization loss sub-state to a temporary data path synchronization loss (LODS) state.

4. The method comprises: a second monitoring module monitoring a second recovery time of the management path signal and the data path signal of the ONU in the temporary LODS state; 4. The downstream signal synchronization method according to claim 2, further comprising: if the second recovery time does not exceed a second predetermined time threshold, the ONU returns to the operating state and continues operation.

5. The method comprises: The downstream synchronization method of claim 4 , further comprising: if the second recovery time exceeds the second predetermined time threshold, the ONU enters an initial state of the downstream synchronization.

6. The downstream signal synchronization method according to claim 1 , wherein in the management path synchronization loss substate, the data path signal of the ONU is synchronized and operates normally.

7. Monitoring a first recovery time for the ONU to regain synchronization of the management path signal in the management path synchronization loss substate includes: the ONU turns on a first timer, the duration of the first timer being set to the first predetermined time threshold; The downstream signal synchronization method of claim 1, further comprising: the ONU determining whether the first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization loss sub-state exceeds the first predetermined time threshold by determining whether the first timer has timed out when synchronization of the management path signal is recovered.

8. monitoring a second recovery time during which the ONU recovers the management path signal and the data path signal in the temporary LODS state; the ONU turns on a second timer, the duration of the second timer being set to the second predetermined time threshold; The downstream signal synchronization method of claim 4, further comprising: the ONU determining whether a second recovery time for the ONU to recover the management path signal and the data path signal in the temporary LODS state exceeds the second predetermined time threshold by determining whether the second timer has timed out when the management path signal and the data path signal are recovered.

9. A downstream signal synchronization system applied to a wavelength division multiplexing passive optical network, comprising: a detection module, used to detect whether a situation occurs in which a downstream signal loses synchronization when the optical network unit ONU is in operation, the downstream signal including a management path signal and a data path signal; a first switching module, used to switch the ONU from the working state to a management path synchronization loss sub-state when a situation occurs in which the synchronization of the management path signal is lost and the data path signal is normally synchronized; a first monitoring module for monitoring a first recovery time for the ONU to recover synchronization of the management path signal in the management path synchronization loss substate; a first return module for returning the ONU from the management path synchronization loss sub-state to the operating state if the first recovery time does not exceed a first predetermined time threshold and the data path signal is still normally synchronized, thereby allowing the ONU to continue operating in the operating state.

10. The system comprises:

10. The downstream signal synchronization system of claim 9, wherein the ONU further includes a second switching module used to switch from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state when a situation occurs in which synchronization of the data path signal is lost within the first predetermined time threshold.

11. The system comprises:

10. The downstream signal synchronization system of claim 9, wherein the ONU further includes a second switching module used to switch from the management path synchronization loss sub-state to a temporary data path synchronization loss LODS state when the first recovery time exceeds the first predetermined time threshold.

12. The system comprises:

12. The downstream signal synchronization system of claim 10 or 11, further comprising a second monitoring module used to monitor a second recovery time for the ONU to recover the management path signal and the data path signal in the temporary LODS state, and if the second recovery time does not exceed a second predetermined time threshold, the ONU returns to the operating state and continues operation, and if the second recovery time exceeds the second predetermined time threshold, the ONU enters an initial state of the downstream signal synchronization.

13. 10. The downstream signal synchronization system according to claim 9, wherein in the management path synchronization loss substate, the data path signal of the ONU is synchronized and operates normally.

14. A downstream signal synchronization device, a processor; a memory coupled to said processor and adapted to store instructions, said instructions, when executed by said processor, causing said processor to perform the method of claim 1.

15. A computer-readable storage medium on which a computer program is stored, 10. A computer-readable storage medium, wherein the computer program, when executed by a processor, implements the downstream signal synchronization method according to claim 1.

16. A computer program comprising instructions, 10. A computer program product comprising instructions which, when executed by a processor, cause the processor to perform the method of claim 1.

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