Downlink signal synchronization method and system

Abstract

The present disclosure relates to a downlink signal synchronization method and system, and relates to the technical field of passive optical networks. The method is applied to a wavelength division multiplexing passive optical network. Specifically, whether a downlink signal synchronization loss occurs can be detected when an optical network unit (ONU) is in a running state. The downlink signal includes a management channel signal and a data channel signal. When the management channel signal synchronization loss occurs while the data channel signal is normally synchronized, the ONU switches from the running state to a management channel synchronization loss sub-state. A first recovery time for the ONU to recover the management channel signal synchronization in the management channel synchronization loss sub-state is monitored. If the first recovery time does not exceed a first preset time threshold, and the data channel signal is still normally synchronized, the ONU returns from the management channel synchronization loss sub-state to the running state. In this way, the problem of ONU disconnection caused by the absence of state migration mode in the original state machine under corresponding conditions can be avoided.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of passive optical networks, and in particular to a downlink signal synchronization method and system. Background Art

[0002] High-speed passive optical network (PON) technology, widely deployed in existing networks, primarily uses time-division multiplexing (TDM) EPON (Ethernet Passive Optical Network) or GPON (Gigabit-Capable PON) systems. Both upstream and downstream transmissions operate on a single wavelength, allocated transmission time. Wavelength division multiplexing (WDM-PON) employs wavelength division multiplexing (WDM) technology, where the PON port of the central office optical line terminal (OLT) and the optical network unit (ONU) on the user side each occupy a pair of wavelength channels in a point-to-point manner. This allows for several times the number of users compared to traditional TDM-PON. It primarily provides network connectivity for government and enterprise customers, wireless bearer services, and other applications. In particular, in the 5G fronthaul sector, the use of WDM-PON can conserve backbone fiber resources and reduce the cost and difficulty of network installation, maintenance, and operation.

[0003] Due to the characteristics of time-division multiplexing (TDM), the ONU registration and activation process in traditional PONs involves states such as ranging and time slot allocation. These states are not required in wavelength-division multiplexing-based WDM-PONs. The basic framework of the ONU registration and activation process in existing WDM-PON systems follows that of traditional PONs. When the ONU activation state machine is in operation, it only specifies state transitions for situations where data channel synchronization is lost. This approach is relatively simple and can potentially cause ONUs to become disconnected.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0005] In order to overcome the problems existing in the related art, the present disclosure provides a downlink signal synchronization method and system to at least solve the problem that the state machine only standardizes the state migration method for the case where the data channel loses synchronization. The method is relatively simple and may cause the ONU to be out of control.

[0006] According to one aspect of the present disclosure, a downlink signal synchronization method is provided, which is applied to a wavelength division multiplexing passive optical network. The method includes:

[0007] When the optical network unit ONU is in operation, detecting whether there is a loss of synchronization of the downlink signal; the downlink signal includes a management channel signal and a data channel signal;

[0008] When the management channel signal synchronization is lost and the data channel signal is normally synchronized, the ONU switches from the running state to the management channel synchronization loss sub-state;

[0009] Monitoring a first recovery time for the ONU to recover synchronization of the management channel signal in the management channel synchronization loss substate;

[0010] If the first recovery time does not exceed a first preset time threshold and the data channel signal is still synchronized normally, the ONU returns from the management channel synchronization loss substate to the running state, so that the ONU continues to work in the running state.

[0011] Optionally, the monitoring of the first recovery time for the ONU to recover the management channel signal synchronization in the management channel synchronization loss substate further includes:

[0012] If the data channel signal synchronization loss occurs within the first preset time threshold, the ONU switches from the management channel synchronization loss sub-state to the temporary data channel synchronization loss LODS state.

[0013] Optionally, the monitoring of the first recovery time for the ONU to recover the management channel signal synchronization in the management channel synchronization loss substate further includes:

[0014] If the first recovery time exceeds the first preset time threshold, the ONU is switched from the management channel synchronization loss sub-state to the temporary data channel synchronization loss LODS state.

[0015] Optionally, the method further includes:

[0016] Monitoring a second recovery time of the ONU for the management channel signal and the data channel signal in the temporary LODS state;

[0017] If the second recovery time does not exceed a second preset time threshold, returning the ONU to the running state to continue working;

[0018] If the second recovery time exceeds the second preset time threshold, the ONU enters the initial state of the downlink signal synchronization.

[0019] Optionally, in the management channel synchronization loss sub-state, the data channel signal synchronization of the ONU operates normally.

[0020] According to one aspect of the present disclosure, a downlink signal synchronization system is provided, which is applied to a wavelength division multiplexing passive optical network. The system includes:

[0021] A detection module is used to detect whether a downlink signal synchronization loss occurs when the optical network unit ONU is in operation; the downlink signal includes a management channel signal and a data channel signal;

[0022] A first switching module is configured to switch the ONU from the running state to the management channel synchronization loss sub-state when the management channel signal synchronization is lost while the data channel signal is normally synchronized;

[0023] A first monitoring module is used to monitor a first recovery time for the ONU to recover the synchronization of the management channel signal in the management channel synchronization loss sub-state;

[0024] A first return module is configured to return the ONU from the management channel synchronization loss substate to the running state if the first recovery time does not exceed a first preset time threshold and the data channel signal is still synchronized normally, so that the ONU continues to operate in the running state.

[0025] Optionally, the system further includes:

[0026] The second switching module is configured to switch the ONU from the management channel synchronization loss substate to the temporary data channel synchronization loss LODS state if the data channel signal synchronization loss occurs within the first preset time threshold.

[0027] Optionally, the system further includes:

[0028] The second switching module is used to switch the ONU from the management channel synchronization loss sub-state to the temporary data channel synchronization loss LODS state if the first recovery time exceeds the first preset time threshold.

[0029] Optionally, the system further includes:

[0030] a second monitoring module, configured to monitor a second recovery time of the ONU for the management channel signal and the data channel signal in the temporary LODS state; if the second recovery time does not exceed a second preset time threshold, the ONU returns to the running state to continue working; if the second recovery time exceeds the second preset time threshold, the ONU enters an initial state of the downlink signal synchronization.

[0031] Optionally, in the management channel synchronization loss sub-state, the data channel signal of the ONU is normally working.

[0032] According to one aspect of the present disclosure, a computer readable storage medium is provided, which stores a computer program, and the computer program is executed by a processor to implement the downlink signal synchronization method of any one of the above.

[0033] In summary, the downlink signal synchronization method provided by the embodiments of the present disclosure is applied to a wavelength division multiplexing passive optical network, and can detect whether a downlink signal synchronization loss occurs when an optical network unit (ONU) is in a running state. The downlink signal includes a management channel signal and a data channel signal. When the management channel signal synchronization loss occurs and the data channel signal is normally synchronized, the ONU is switched from the running state to a management channel synchronization loss sub-state. A first recovery time of the ONU for recovering the management channel signal synchronization in the management channel synchronization loss sub-state is monitored. If the first recovery time does not exceed a first preset time threshold and the data channel signal is still normally synchronized, the ONU returns from the management channel synchronization loss sub-state to the running state, so that the ONU continues to normally work in the running state. In this way, the management channel synchronization loss sub-state is introduced in the running state, which makes up for the fact that the existing ONU registration activation state mechanism does not consider the management channel signal synchronization loss, and avoids the problem of ONU disconnection due to the absence of state migration mode in the original state machine.

[0034] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor based on these drawings.

[0036] Figure 1 is an ONU registration activation process of a wavelength division multiplexing passive optical network system in the related art;

[0037] Figure 2 This is a flowchart of a downlink signal synchronization method provided by an embodiment of the present disclosure;

[0038] Figure 3 This is a flow chart of ONU synchronization recovery provided by an embodiment of the present disclosure;

[0039] Figure 4 This is a block diagram of a downlink signal synchronization system provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0040] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present disclosure will be more comprehensive and complete and will fully convey the concepts of the example 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, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or that other methods, components, devices, steps, etc. may be employed. In other cases, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0041] In addition, the accompanying drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale. Identical reference numerals in the figures denote identical or similar parts, and thus repetitive descriptions thereof will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities that do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0042] In a wavelength division multiplexing passive optical network (WDM-PON), user data channels and management client channels are separated in the transmission convergence layer (TC). User data is not processed by the TC layer, while management data is processed by the TC layer in a specific manner. Transcoded and transparent transmission modes are used. Therefore, in the ONU registration and activation process for a wavelength division multiplexing passive optical network (WDM-PON), the disclosed embodiments primarily include the following states: initial state, sequence number state, operating state, and temporary data channel synchronization loss state.

[0043] The initial state (01) can be when the ONU is powered on for the first time or restarted, the ONU enters the initial state (01), and when in the initial state (01), the ONU can perform the operation of turning on the receiver and turning off the transmitter. The initial state (01) can also include an unsynchronized sub-state (01.1) and a configuration template learning sub-state (01.2). The unsynchronized sub-state (01.1) can be the entrance of the initial state (01), which can be when the ONU attempts to synchronize on the PON wavelength channel. The configuration template learning sub-state (01.2) can be used for the ONU to obtain configuration template information through a downstream PLOAM message to determine whether the wavelength channel is available. Once it is determined that the downstream synchronization of the wavelength channel is successful, the ONU can enter the configuration template learning sub-state (01.2).

[0044] The sequence number state (O2-3) can be the ONU activated transmitter. The sequence number state (O2-3) can be used for the ONU to periodically send a specific PLOAM message to provide authentication information until the OLT CT confirms the allocation of the ONU-ID. When the time of the ONU in the sequence number state (O2-3) appears to be out of time, the ONU can return from the sequence number state (O2-3) to the initial state (01).

[0045] The running state (O5) can be used for the ONU to receive and send signals through the PON channel. In the embodiments of the present disclosure, the running state (O5) can also include a management channel synchronization loss sub-state (O5.1). Specifically, when the ONU in the running state (O5) appears to have normal data channel signal synchronization and lost management channel signal synchronization, the ONU enters the management channel synchronization loss sub-state (O5.1). After entering the management channel synchronization loss sub-state (O5.1), the ONU can start a timer TO1, which records the time of the ONU in the management channel synchronization loss sub-state (O5.1). If the ONU restores the management channel signal synchronization before TO1 expires, the ONU returns to the running state (O5). If TO1 expires, the ONU will stop data transmission and enter the temporary data channel synchronization loss state (O6).

[0046] The temporary data channel synchronization loss state (O6) can be entered after the running state (O5), i.e., when the ONU in the running state (O5) appears to have lost data channel signal synchronization or is in the management channel loss state (O5.1) for a timeout. The temporary data channel synchronization loss state (O6) can be referred to as the temporary LODS state.

[0047] Specifically, after the ONU is connected 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 channel, synchronizes with the data and management channels, collects configuration template information, and confirms basic parameters. Once the ONU determines the wavelength of the downstream channel, it tunes the transmitter and declares its existence and authenticates via a specific message. Once the OLT CT successfully authenticates the ONU, it will confirm via a specific message, at which point the ONU enters the operational state (O5). If an ONU in the operational state (O5) loses synchronization on the downstream data channel, the ONU will enter the temporary LODS state (O6). In the temporary LODS state (O6), it is possible to detect whether the time required to restore data channel signal synchronization and management channel signal synchronization is less than a preset threshold. If the required time is less than the preset threshold, that is, the ONU successfully restores data channel signal synchronization and management channel signal synchronization within the preset threshold, then the ONU can return to the running state (O5). If the required time is greater than the preset threshold, that is, the ONU cannot successfully restore data channel signal synchronization and management channel signal synchronization within the preset threshold, then the ONU can return to the unsynchronized sub-state (O1.1) in the initial state (O1) for reactivation. When the ONU in the running state (O5) loses management channel synchronization while the data channel is still receiving and sending normally, there is no corresponding state migration method in the relevant technology, which may cause the ONU to be disconnected from the management.

[0048] Figure 1 This is the ONU registration and activation process of the wavelength division multiplexing passive optical network in the related technology, such as Figure 1As shown, 01. When the downstream signal of an ONU in the unsynchronized substate (O1.1) recovers synchronization (DSYNC), that is, both the data channel signal and the management channel signal recover synchronization, the ONU enters the configuration template learning substate (O1.2); 02. When the data channel loss of synchronization (LODS) or the downstream wavelength channel (DWLCH) is mismatched, the ONU in the configuration template learning substate (O1.2) enters the unsynchronized substate (O1.1); 03. When the downstream wavelength channel (DWLCH) of an ONU in the initial state (O1) can operate normally, the ONU enters the sequence number state (O2-3); 04. When the ONU in the sequence number state (O2-3) is executing the ONU-ID allocation, the ONU enters the running state (O5); 05. When the data channel loss of synchronization (LODS) occurs, the ONU in the running state (O5) , enters the temporary LODS state (O6); 06. For the ONU in the temporary LODS state (O6), the downstream signal is restored to synchronization (DSYNC), that is, the data channel signal and the management channel signal are restored to synchronization, and enters the temporary LODS state (O6); 07. For the ONU in the sequence number state (O2-3), if any of the following situations occurs: data channel synchronization loss, stay time in the sequence number state (O2-3) times out, or ONU-ID request is released, it enters the unsynchronized sub-state (O1.1); 08. For the ONU in the running state (O5), if the ONU-ID request is released, it enters the unsynchronized sub-state (O1.1); 09. For the ONU in the temporary LODS state (O6), if the stay time in the temporary LODS state (O6) times out, it enters the unsynchronized sub-state (O1.1).

[0049] Figure 2 This is a flowchart of a downlink signal synchronization method provided by an embodiment of the present disclosure, which is applied to a wavelength division multiplexing passive optical network, such as Figure 2 As shown, the method may include:

[0050] Step S101: When the optical network unit (ONU) is in operation, detect whether a downlink signal synchronization loss occurs; the downlink signal includes a management channel signal and a data channel signal.

[0051] In the embodiment of the present disclosure, the optical network unit ONU may go through the ONU registration and activation process until it reaches the operating state. In the operating state, it is necessary to synchronize the downlink signal. During the synchronization process, the management channel signal synchronization may be lost, the data channel signal synchronization may be lost, or both the management channel signal and the data channel signal may be lost. Therefore, by detecting whether the downlink signal synchronization is lost, the problem of signal synchronization loss can be solved in time to avoid the problem of ONU disconnection due to signal synchronization loss.

[0052] Step S102: When the management channel signal synchronization is lost and the data channel signal is normally synchronized, the ONU switches from the running state to the management channel synchronization loss sub-state.

[0053] In the embodiment of the present disclosure, since the ONU is currently in the running state, when the management channel signal synchronization is lost while the data channel signal is synchronized normally, the ONU can enter the management channel synchronization loss sub-state from the running state. The management channel synchronization loss sub-state can be referred to as the MLODS sub-state. In the MLODS sub-state, the data channel synchronization of the ONU is normal, that is, user data can be sent and received normally and will not be affected by the MLODS sub-state.

[0054] Step S103: monitoring a first recovery time for the ONU to recover synchronization of the management channel signal in the management channel synchronization loss sub-state.

[0055] In the embodiment of the present disclosure, when the ONU is in the MLODS sub-state, the time for restoring the synchronization of the management channel signal can be recorded to obtain a first recovery time, and the first recovery time can be monitored in real time to see if it exceeds a first preset time threshold. The first recovery time can be the time for recording the ONU in the MLODS sub-state, and the first time threshold can be pre-set according to actual conditions, and is used to limit the time the ONU stays in the MLODS sub-state to try to restore the synchronization of the management channel, thereby avoiding the problem of the management channel synchronization being lost for too long, causing the ONU to be out of control in the MLODS sub-state. It should be noted that in the MLODS sub-state, the ONU only fails to synchronize the management channel signal, while the data channel signal synchronization is normal. Therefore, in the MLODS sub-state, the data channel can still operate normally, that is, user data transmission and reception can still operate normally.

[0056] Step S104: If the first recovery time does not exceed a first preset time threshold and the data channel signal is still synchronized normally, the ONU returns from the management channel synchronization loss substate to the running state, so that the ONU continues to work in the running state.

[0057] In an embodiment of the present disclosure, if the first recovery time does not exceed the first preset time threshold, that is, the management channel signal recovers synchronization within the first preset time threshold, and the data channel signal is still synchronized normally, the ONU can be returned from the MLODS sub-state to the running state, so that the ONU can continue to work normally in the running state and perform normal sending and receiving operations on the downlink signal.

[0058] In summary, the downlink signal synchronization method provided by the embodiment of the present application is applied to a wavelength division multiplexing passive optical network, and can detect whether downlink signal synchronization loss occurs when an optical network unit (ONU) is in a running state. The downlink signal includes a management channel signal and a data channel signal. When the management channel signal synchronization loss occurs and the data channel signal is normally synchronized, the ONU switches from the running state to a management channel synchronization loss (MLODS) substate, monitors a first recovery time of the ONU in the MLODS substate for recovering the management channel signal synchronization, and returns to the running state from the MLODS substate if the first recovery time does not exceed a first preset time threshold and the data channel signal is still normally synchronized, so that the ONU continues to normally work in the running state. In this way, the MLODS substate is introduced in the running state, the situation of the management channel signal synchronization loss is considered in the existing ONU registration activation state mechanism, and the problem of ONU disconnection caused by the absence of state migration mode in the original state machine is avoided.

[0059] Optionally, after the first recovery time of the ONU in the MLODS substate for recovering the management channel signal synchronization is monitored, the method further includes:

[0060] If the data channel signal synchronization loss occurs within the first preset time threshold, the ONU switches from the MLODS substate to a temporary data channel synchronization loss (LODS) state.

[0061] In the embodiment of the present disclosure, the ONU can be in the MLODS substate, and the data channel signal synchronization loss occurs, that is, the data channel signal synchronization loss occurs within the first preset time threshold. Since the data channel signal synchronization and the management channel signal synchronization of the ONU are both lost, the ONU can directly switch to the temporary LODS state to attempt to recover the downlink signal synchronization.

[0062] Optionally, after the first recovery time of the ONU in the MLODS substate for recovering the management channel signal synchronization is monitored, the method further includes:

[0063] If the first recovery time exceeds the first preset time threshold, the ONU switches from the MLODS substate to the temporary LODS state.

[0064] In an embodiment of the present disclosure, the first recovery time for restoring the management channel signal synchronization may exceed a first preset time threshold, that is, if the management channel signal synchronization cannot be restored within the first preset time threshold, the ONU may be returned from the MLODS sub-state to the temporary LODS state, so that the ONU attempts to restore the downstream signal synchronization in the temporary LODS state.

[0065] Optionally, the downlink signal synchronization method in the embodiment of the present disclosure further includes:

[0066] Monitor the second recovery time of the management channel signal and the data channel signal of the ONU in the temporary LODS state; if the second recovery time does not exceed the second preset time threshold, return the ONU to the running state to continue working; if the second recovery time exceeds the second preset time threshold, the ONU enters the initial state of the downlink signal synchronization.

[0067] In the disclosed embodiment, for an ONU in a temporary LODS state, the time it takes for the ONU to restore a management channel signal and a data channel signal can be recorded to obtain a second recovery time, and the second recovery time can be detected to determine whether the second recovery time exceeds a second preset time threshold. The second recovery time can be the time the ONU is in the temporary LODS state, and the second preset time threshold can be used to limit the time the ONU stays in the LODS state. The specific value can be set according to actual conditions.

[0068] In the embodiment of the present disclosure, if the second recovery time does not exceed the second preset time threshold, that is, within the second preset time threshold, the synchronization of the management channel signal and the data channel signal of the ONU is successfully restored, then the ONU can return from the temporary LODS state to the running state and continue normal operation. If the second recovery time exceeds the second preset time threshold, that is, within the second preset time threshold, the synchronization of the management channel signal and the data channel signal of the ONU cannot be restored, then the ONU can directly enter the initial state of downlink signal synchronization.

[0069] For example, Figure 3 This is a flow chart of ONU synchronization recovery provided by an embodiment of the present disclosure, such as Figure 3As shown in FIG11 , 11. If the ONU in the running state (O5) loses synchronization of the management channel while the data channel works normally, it enters the MLODS sub-state (O5.1) and tries to restore synchronization within a certain period of time. At this time, user data transmission and reception are still normal and will not be affected. 12. If the ONU in the MLODS sub-state (O5.1) successfully restores synchronization of the management channel signal and the synchronization of the data channel signal still works normally, it returns to the running state (O5). 13. If the ONU in the MLODS sub-state (O5.1) restores synchronization of the management channel signal, it returns to the running state (O5). If the ONU in the running state (O5) loses data channel synchronization and cannot send and receive normal user data, it directly enters the temporary LODS state (O6) to restore data channel synchronization; 15. If the ONU in the temporary LODS state (O6) successfully restores the synchronization of the data channel and the management channel, it returns to the running state (O5).

[0070] Table 1

[0071]

[0072] For example, Table 1 characterizes the events that can be used for state migration in the embodiment of the present disclosure. If the ONU is in the running state O5, the management channel signal synchronization loss occurs, the first preset time threshold is turned on, and the state is switched to the MLODS sub-state, while the management channel synchronization loss state O5.1 and the LODS state O6 are not applicable to the MLODS sub-state; in the management channel synchronization loss state O5.1, the management channel synchronization recovery (MDSYNC) occurs, the first preset time threshold can be stopped, and the state is switched to the running state O5, while the running state O5 and the LODS state O6 are not applicable to MDSYNC; in the management channel synchronization loss state O5.1, LODS occurs, that is, the data channel signal synchronization is lost, the second preset time threshold can be turned on, and the state is switched to the LODS state O6, and in the management channel synchronization loss state O5 .1, LODS appears, the second preset time threshold can be turned on and the state O6 can be switched to LODS. LODS state O6 is not applicable to LODS; restoring downlink synchronization (DSYNC) is not applicable to running state O5 and management channel synchronization loss state O5.1. In LODS state O6, DSYNC appears, the second preset time threshold can be stopped and the state O5 can be switched to running state O5; in management channel synchronization loss state O5.1, the first preset time threshold times out, the second preset time threshold can be turned on and the state O6 can be switched to LODS. The timeout of the first preset time threshold is not applicable to running state O5 and LODS state O6; in LODS state O6, the second preset time threshold times out, the ONU-ID value can be discarded and the state O1.1 can be switched to unsynchronized state O1.1 (i.e., reactivated).

[0073] Figure 4 This is a downlink signal synchronization system provided by an embodiment of the present disclosure, such as Figure 4 As shown, the system 30 may include:

[0074] The detection module 301 is used to detect whether the downlink signal synchronization is lost when the optical network unit ONU is in operation; the downlink signal includes a management channel signal and a data channel signal;

[0075] A first switching module 302 is configured to switch the ONU from the running state to the management channel synchronization loss sub-state when the management channel signal synchronization is lost while the data channel signal is normally synchronized;

[0076] A first monitoring module 303 is configured to monitor a first recovery time for the ONU to recover synchronization of the management channel signal in the management channel synchronization loss sub-state;

[0077] The first return module 304 is configured to return the ONU from the management channel synchronization loss substate to the running state if the first recovery time does not exceed a first preset time threshold and the data channel signal is still synchronized normally, so that the ONU continues to operate in the running state.

[0078] In summary, the downlink signal synchronization system provided by the embodiments of the present invention is applied to a wavelength division multiplexing passive optical network. When an optical network unit (ONU) is in the operating state, it can detect whether downlink signal synchronization has been lost. The downlink signal includes a management channel signal and a data channel signal. When the management channel signal synchronization is lost while the data channel signal is normally synchronized, the ONU switches from the operating state to a management channel synchronization loss sub-state. The system monitors the first recovery time for the ONU to restore management channel signal synchronization in the management channel synchronization loss sub-state. If the first recovery time does not exceed a first preset time threshold and the data channel signal is still normally synchronized, the ONU returns from the management channel synchronization loss sub-state to the operating state, allowing the ONU to continue normal operation in the operating state. Thus, by introducing a sub-state for only management channel synchronization loss in the operating state, the existing ONU registration and activation state mechanism fails to consider the situation of management channel signal synchronization loss, thus avoiding the problem of ONU disconnection caused by the lack of a corresponding state transition method in the original state machine.

[0079] Optionally, the system 30 further includes:

[0080] The second switching module is configured to switch the ONU from the management channel synchronization loss substate to the temporary data channel synchronization loss LODS state if the data channel signal synchronization loss occurs within the first preset time threshold.

[0081] Optionally, the system 30 further includes:

[0082] The second switching module is configured to switch the ONU from the management channel synchronization loss sub-state to the temporary data channel synchronization loss LODS state if the first recovery time exceeds the first preset time threshold.

[0083] Optionally, the system 30 further includes:

[0084] The second monitoring module is used to monitor the second recovery time of the ONU for the management channel signal and the data channel signal in the temporary LODS state; if the second recovery time does not exceed the second preset time threshold, the ONU is returned to the running state to continue working; if the second recovery time exceeds the second preset time threshold, the ONU enters the initial state of the downlink signal synchronization.

[0085] Optionally, in the management channel synchronization loss sub-state, the data channel signal synchronization of the ONU operates normally. The specific details of each module in the above downlink signal synchronization system have been described in detail in the corresponding downlink signal synchronization method, so they are not repeated here.

[0086] It should be noted that although several modules or units of the device for action execution are mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of the present disclosure, the features and functions of two or more modules or units described above can be concretized in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided into multiple modules or units to be concretized.

[0087] Furthermore, although the steps of the method of the present disclosure are described in a particular order in the accompanying drawings, this does not require or imply that the steps must be performed in this particular order, or that all steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

[0088] In an exemplary embodiment of the present disclosure, an electronic device capable of implementing the above method is also provided.

[0089] Those skilled in the art will appreciate that various aspects of the present disclosure may be implemented as systems, methods, or program products. Therefore, various aspects of the present disclosure may be implemented in the following forms: a complete hardware implementation, a complete software implementation (including firmware, microcode, etc.), or a combination of hardware and software implementations, which may be collectively referred to herein as "circuits," "modules," or "systems."

[0090] Through the description of the above embodiments, it is easy for those skilled in the art to understand that the example embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solution according to the embodiments of the present disclosure can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which can be a personal computer, a server, a terminal device, or a network device, etc.) to execute the method according to the embodiments of the present disclosure.

[0091] In exemplary embodiments of the present disclosure, a computer-readable storage medium is also provided, on which is stored a program product capable of implementing the aforementioned methods of this specification. In some possible implementations, various aspects of the present disclosure may also be implemented in the form of a program product comprising program code. When the program product is executed on a terminal device, the program code is configured to cause the terminal device to execute the steps described in the "Exemplary Methods" section of this specification according to various exemplary embodiments of the present disclosure.

[0092] According to an embodiment of the present disclosure, a program product for implementing the above-mentioned method can be a portable compact disc read-only memory (CD-ROM) and include program code, and can be run on a terminal device, such as a personal computer. However, the program product of the present disclosure is not limited thereto. In this document, a readable storage medium can be any tangible medium containing or storing a program, which can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0093] The program product may be implemented in 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, device, or component, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, 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 thereof.

[0094] A computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium that can transmit, propagate, or transfer a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0095] The program code embodied on the readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0096] The program code for performing the operations of the present disclosure may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, and the like, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a stand-alone 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 cases involving 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., via the Internet using an Internet service provider).

[0097] Furthermore, the figures above are merely illustrative of the processes included in the methods according to exemplary embodiments of the present disclosure and are not intended to be limiting. It is readily understood that the processes illustrated in the figures above do not indicate or limit the temporal order of these processes. Furthermore, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0098] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow from the general principles of the present disclosure and include common knowledge or customary techniques in the art not invented herein. The specification and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the claims.

Claims

1. A downlink signal synchronization method, characterized in that: Applied to a wavelength division multiplexing passive optical network, the method comprises: When the optical network unit ONU is in operation, detecting whether there is a loss of synchronization of the downlink signal; the downlink signal includes a management channel signal and a data channel signal; When the management channel signal synchronization is lost and the data channel signal is normally synchronized, the ONU switches from the running state to the management channel synchronization loss sub-state; Monitoring a first recovery time for the ONU to recover synchronization of the management channel signal in the management channel synchronization loss substate; If the first recovery time does not exceed a first preset time threshold and the data channel signal is still synchronized normally, the ONU returns from the management channel synchronization loss substate to the running state, so that the ONU continues to work in the running state.

2. The method according to claim 1, characterized in that The monitoring of the ONU after a first recovery time for recovering the management channel signal synchronization in the management channel synchronization loss sub-state further includes: If the data channel signal synchronization loss occurs within the first preset time threshold, the ONU switches from the management channel synchronization loss sub-state to the temporary data channel synchronization loss LODS state.

3. The method according to claim 1, characterized in that The monitoring of the ONU after a first recovery time for recovering the management channel signal synchronization in the management channel synchronization loss sub-state further includes: If the first recovery time exceeds the first preset time threshold, the ONU is switched from the management channel synchronization loss sub-state to the temporary data channel synchronization loss LODS state.

4. The method according to claim 2 or 3, characterized in that The method further comprises: Monitoring a second recovery time of the ONU for the management channel signal and the data channel signal in the temporary LODS state; If the second recovery time does not exceed a second preset time threshold, returning the ONU to the running state to continue working; If the second recovery time exceeds the second preset time threshold, the ONU enters the initial state of the downlink signal synchronization.

5. The method according to claim 1, wherein In the management channel synchronization loss sub-state, the data channel signal synchronization of the ONU operates normally.

6. A downlink signal synchronization system, characterized in that: Applied to a wavelength division multiplexing passive optical network, the system includes: A detection module is used to detect whether a downlink signal synchronization loss occurs when the optical network unit ONU is in operation; the downlink signal includes a management channel signal and a data channel signal; A first switching module is configured to switch the ONU from the running state to the management channel synchronization loss sub-state when the management channel signal synchronization is lost while the data channel signal is normally synchronized; A first monitoring module is used to monitor a first recovery time for the ONU to recover the synchronization of the management channel signal in the management channel synchronization loss sub-state; A first return module is configured to return the ONU from the management channel synchronization loss substate to the running state if the first recovery time does not exceed a first preset time threshold and the data channel signal is still synchronized normally, so that the ONU continues to operate in the running state.

7. The system according to claim 6, characterized in that The system further comprises: The second switching module is configured to switch the ONU from the management channel synchronization loss substate to the temporary data channel synchronization loss LODS state if the data channel signal synchronization loss occurs within the first preset time threshold.

8. The system according to claim 6, wherein: The system further comprises: The second switching module is configured to switch the ONU from the management channel synchronization loss sub-state to the temporary data channel synchronization loss LODS state if the first recovery time exceeds the first preset time threshold.

9. The system according to claim 7 or 8, characterized in that The system further comprises: The second monitoring module is used to monitor the second recovery time of the ONU for the management channel signal and the data channel signal in the temporary LODS state; if the second recovery time does not exceed the second preset time threshold, the ONU is returned to the running state to continue working; if the second recovery time exceeds the second preset time threshold, the ONU enters the initial state of the downlink signal synchronization.

10. The system according to claim 6, wherein: In the management channel synchronization loss sub-state, the data channel signal synchronization of the ONU operates normally.

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