CN113824506B

CN113824506B - Optical signal processing method, optical transceiver, controller and optical line terminal

Info

Publication number: CN113824506B
Application number: CN202010569549.8A
Authority: CN
Inventors: 林华枫; 李远谋; 曾小飞
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-06-20
Filing date: 2020-06-20
Publication date: 2023-01-06
Anticipated expiration: 2040-06-20
Also published as: CN113824506A; WO2021254225A1

Abstract

Embodiments of the present disclosure relate to an optical signal processing method, an optical transceiver, a controller, and an optical line terminal. The optical line terminal includes an optical transceiver and a controller. The optical transceiver includes a receiver, the receiver including: a light detector configured to receive an optical signal from an optical network unit; and an amplifier coupled with the light detector and configured to receive an indication signal from the controller for indicating an operating mode of the controller and to adjust a light processing parameter of the receiver for the light signal based on the indication signal. The controller includes: a first signal generator configured to generate the indication signal and provide the indication signal to the optical transceiver. According to the scheme of the embodiment of the disclosure, the stability and the accuracy of the optical receiving process of the optical line terminal side can be ensured. In addition, the design complexity of the optical transceiver, especially the amplifier, can be reduced, and the high integration of the optical line terminal is promoted.

Description

Optical signal processing method, optical transceiver, controller and optical line terminal

Technical Field

Embodiments of the present disclosure relate to the field of Optical communications, and more particularly, to processing of reception of Optical signals at an Optical Line Terminal (OLT).

Background

Currently, the mainstream Optical fiber access system is a Passive Optical Network (PON) system. The PON system includes an OLT at a central office side and an Optical Network Unit (ONU) at a terminal side. One OLT may receive Time Division Multiplexed (TDMA) optical signals, also referred to as upstream light, from a plurality of ONUs. Since the optical signals from each ONU may vary in both amplitude and length of time, it has been a research focus in the art to quickly adjust the optical processing parameters of the OLT for these optical signals in order to correctly process and identify these optical signals.

Generally, when an ONU is powered on, the ONU needs to interact with an OLT to complete registration and log on, and normal data transceiving can be performed after the registration and log on. However, in the process of registering online, since the OLT cannot predict when the ONU is powered on, that is, cannot predict the time when the upstream light arrives, the OLT may not adjust the optical processing parameters at an appropriate time, or even cannot start adjusting the optical processing parameters, so that the upstream light from the ONU cannot be correctly processed and identified, or even the upstream light cannot be registered online.

Disclosure of Invention

In general, embodiments of the present disclosure provide an improved optical reception processing scheme at an OLT.

According to a first aspect of embodiments of the present disclosure, there is provided an optical signal processing method implemented at an optical transceiver. The method comprises the following steps: the optical transceiver receives an optical signal from the optical network unit; the optical transceiver receives an indication signal from a controller, wherein the indication signal is used for indicating the working mode of the controller; and based on the indication signal, the optical transceiver adjusts an optical processing parameter of a receiver in the optical transceiver for the optical signal.

According to a second aspect of embodiments of the present disclosure, there is provided a method of optical signal processing implemented at a controller. The method comprises the following steps: a controller generates an indication signal, wherein the indication signal indicates the working mode of the controller; and the controller provides the indication signal to an optical transceiver to cause the optical transceiver to adjust an optical processing parameter of a receiver of the optical transceiver based on the indication signal.

According to a third aspect of the disclosed embodiments, an optical transceiver is provided. The optical transceiver includes: a receiver configured to receive an optical signal from an optical network unit; and an amplifier coupled with the receiver and configured to: receiving an indication signal from a controller, wherein the indication signal is used for indicating the working mode of the controller; and adjusting, based on the indication signal, an optical processing parameter of the receiver for the optical signal.

According to a fourth aspect of embodiments of the present disclosure, a controller is provided. The controller includes: a first signal generator configured to: generating an indication signal indicating an operating mode of the controller; and providing the indication signal to an optical transceiver to cause the optical transceiver to adjust an optical processing parameter of a receiver in the optical transceiver based on the indication signal.

According to a fifth aspect of the embodiments of the present disclosure, there is provided an optical line terminal. The olt comprises an optical transceiver according to the third aspect and a controller according to the fourth aspect.

As will be understood from the following description of example embodiments, according to the technical solution presented herein, stability and accuracy of optical reception processing on the OLT side during ONU registration coming online can be ensured. In addition, the complexity of the optical reception process on the OLT side can be reduced, and the high integration of the OLT can be promoted.

It should be understood that the statements made in this summary are not intended to limit the critical or essential features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

The above and other features, advantages and aspects of various embodiments of the present disclosure will become more apparent by referring to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, like or similar reference characters designate like or similar elements, and wherein:

FIG. 1 illustrates a schematic diagram of an example communication system in which embodiments of the present disclosure may be implemented;

fig. 2 is a schematic diagram showing a light reception process at the OLT side according to the conventional scheme;

figure 3 shows a block schematic of an optical line terminal according to one embodiment of the present disclosure;

FIG. 4 shows a flow diagram of an optical signal processing method according to one embodiment of the present disclosure;

FIG. 5 shows a flow diagram of a method of adjusting a light processing parameter according to one embodiment of the present disclosure; and

fig. 6 shows a flow diagram of an optical signal processing method according to one embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure have been illustrated in the accompanying drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather are provided for a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the disclosure are for illustration purposes only and are not intended to limit the scope of the disclosure.

The terms "include" and variations thereof as used herein are inclusive and open-ended, i.e., "including but not limited to. The term "based on" is "based, at least in part, on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment". Relevant definitions for other terms will be given in the following description.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the listed terms.

The term "circuitry" as used herein refers to one or more of the following:

(a) Hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry); and

(b) A combination of hardware circuitry and software, such as (if applicable): (i) A combination of analog and/or digital hardware circuitry and software/firmware, and (ii) any portion of a hardware processor in combination with software (including a digital signal processor, software, and memory that work together to cause a device such as an Optical Line Terminal (OLT) or other computing device to perform various functions); and

(c) A hardware circuit and/or processor, such as a microprocessor or a portion of a microprocessor, that requires software (e.g., firmware) for operation, but may lack software when software is not required for operation.

The definition of circuit applies to all usage scenarios of this term in this application, including any claims. As another example, the term "circuitry" as used herein also covers an implementation of merely a hardware circuit or processor (or multiple processors), or a portion of a hardware circuit or processor, or software or firmware accompanying it. For example, the term "circuitry" would also cover a baseband integrated circuit or processor integrated circuit or a similar integrated circuit in an OLT or other computing device, as applicable to the particular claim element.

As used herein, the term "communication system" may be a PON-based communication system, such as a Gigabit-Capable Passive Optical Network (G-PON), a 10 Gigabit-Capable Passive Optical Network (XG-PON), a 10 Gigabit-Symmetric Passive Optical Network (XGS-PON), a 50 Gigabit-Capable Passive Optical Network (50G-PON), a 50 Gigabit-Capable Passive Optical Network, and so forth. The communication system may also be any wired or wireless communication system capable of implementing embodiments of the present disclosure. In view of the rapid development of communication technology, there will of course be future types of communication technology and systems with which the present invention may be combined. It should not be considered as limiting the scope of the disclosure to only the above-described systems.

Fig. 1 illustrates a schematic diagram of an example communication system 100 in which embodiments of the present disclosure may be implemented. As shown in fig. 1, the system 100 may be a PON system, which includes ONUs 111, 112, and 113 (which may also be referred to as an ONU 110 hereinafter for convenience) and an OLT 120. The ONUs 111, 112, and 113 may communicate with the OLT120 via an optical splitter 130. It should be understood that the number of ONUs 110 is not limited to the example shown in fig. 1, but may include a greater or lesser number, and the number of OLTs 120 is not limited to the example shown in fig. 1, but may include a greater number. Furthermore, their implementation is not limited to the specific examples described above, but may be implemented in any suitable manner.

The PON system 100 shown in fig. 1 includes downstream transmission and upstream transmission. Downstream transmission refers to data transmission (also referred to herein as optical signal transmission) from the OLT120 to the ONUs 110, and upstream transmission refers to data transmission from the ONUs 110 to the OLT 120. Generally, downlink transmission is to transmit data in a broadcast manner. At OLT120, the downstream data stream is encapsulated into an ethernet packet and is appended with a corresponding Identifier (ID), with

ONUs

111, 112 and 113 being associated with different IDs. At the splitter 130, the downstream data stream will be broadcast to each branch in three groups of signals, so all

ONUs

111, 112 and 113 will receive the same data. After receiving the data transmitted from the OLT120, the

ONUs

111, 112, and 113 determine whether to process or discard the data stream based on the ID. For example, data streams with an ID associated therewith are processed, while data streams with an ID not associated therewith are discarded, and vice versa. It should be noted here that the number of groups into which the downstream data stream is divided may be associated with the number of corresponding ONUs. The number of sets is not limited to the specific example numbers described above, but may be a greater or lesser number.

The uplink transmission is to transmit optical signals in a TDMA manner. For example, after the

ONUs

111, 112, and 113 successfully register on line, the OLT120 may allocate a specific bandwidth, i.e., a time slot allocated during data transmission, to the

ONUs

111, 112, and 113 according to configuration information such as a data traffic type, so as to perform data transmission. The

ONUs

111, 112 and 113 transmit data when the time slots to which the ONUs belong arrive, and send the data in sequence, so that uplink data collision is avoided. The respective optical signals transmitted by the

ONUs

111, 112, and 113 in the time slot to which the ONUs belong are aggregated by the optical splitter 130 to form a time-division multiplexed optical signal, and the optical signal is transmitted to the OLT 120.

Since the traffic type of each ONU 110 and the distance from the OLT120 will typically differ, the optical signals from each ONU 110 also differ in amplitude and length of time. Therefore, how to recover the optical signal of each ONU 110 from the received optical signal at the OLT120 is always a research hotspot receiving much attention.

In general, OLT120 may include two modes of operation: a windowing mode and a data transceiving mode. In the windowing mode, the OLT120 may allocate a specific time slot for an ONU to be on-line to receive an optical signal from the ONU and perform a ranging process, thereby completing registration on-line. The OLT120 may switch to a windowing mode every predetermined time in order to discover a new ONU to be brought online and to include it in the PON system. After the ONU registration is completed, the OLT120 may enter a data transceiving mode to perform normal data transceiving.

As shown in fig. 1, the OLT120 may include an optical transceiver 121 and a controller 122. The optical transceiver 121 may include a transmitter 141 and a receiver 142. It should be understood that OLT120 and optical transceiver 121 may also include other additional modules and are not limited to the examples herein. The transmitter 141 is configured to convert transmission data to be transmitted to the ONU 110 from the controller 122 into a downlink optical signal, and provide the downlink optical signal to the ONU 110 via the optical splitter 130. The receiver 142 is configured to receive the upstream optical signal from the ONU 110 and convert the upstream optical signal into an electrical signal, which is then provided to the controller 122.

However, in the windowing mode, since the controller cannot predict the time of upstream light arrival of the ONU, it is generally not possible in conventional schemes to reset the receiver at the appropriate time. This is explained in detail below with reference to fig. 2.

Fig. 2 shows a schematic diagram of an optical reception process at the OLT200 side according to the conventional scheme. As shown in fig. 2, OLT200 may comprise a receiver 210 and a controller 220 of an optical transceiver. For the sake of brevity, the transmitter of the optical transceiver is not shown here. The receiver 210 may include a photo-detector 201, a Trans-Impedance Amplifier (TIA) 202, and a Limiting Amplifier (LA) 203. The optical signal from the ONU 110 may be converted into a current signal by the optical detector 201, which may be converted into a voltage signal by the TIA 202 and amplified. The amplified voltage signal may be converted into a standard digital level signal by LA 203, which is output to the controller 220 as a reception data output RX of the optical transceiver 310.

Conventionally, in order to solve the problem that the controller 220 cannot predict the arrival time of the upstream light, the LA 203 is designed to output the detection signal SD to the controller 220 when the optical detector 201 detects the optical signal, so that the controller 220 can be made aware that the receiver 210 has received the optical signal. Upon receiving the detection signal SD, the controller 220 may send a RESET signal RESET to the receiver 210 for resetting the receiver 210. However, to reduce the design difficulty of the TIA 202, in some cases, the TIA 202 may be designed to operate based on a reset signal. In still other cases, LA 203 may also be designed to operate based on the RESET signal RESET. In the data transceiving mode, the controller 220 may determine a specific arrival time of the ONU upstream light according to Dynamic Bandwidth Allocation (DBA) information, and may further output a RESET signal RESET at an appropriate time, so that the TIAs 202 and the LA 203 may normally operate based on the RESET signal RESET. However, in the windowing mode, the controller 220 cannot predict the arrival time of the ONU upstream light, and thus cannot provide the RESET signal RESET. This will cause the TIA 202 and the LA 203 to fail to operate normally, and the detection signal SD cannot be provided to the controller 220. In the absence of the detection signal SD, the controller 220 cannot output the RESET signal RESET, resulting in occurrence of a dead cycle.

In view of the room for improvement in the known solutions, embodiments of the present disclosure propose an improved light reception processing scheme. In general, according to the solution proposed herein, the optical transceiver is informed of the operating mode of the controller, so that the optical transceiver can adjust the optical processing parameters of the receiver in time based on the operating mode, thereby ensuring the processing of the optical signal. For ease of understanding, various example embodiments of the present disclosure are described in detail below in conjunction with fig. 3-6.

Fig. 3 shows a schematic block diagram of an OLT 300 according to one embodiment of the present disclosure. The OLT 300 may be implemented as, or as part of, the OLT120 of fig. 1. It should be understood that OLT 300 may include other additional components not shown or omit some of the components shown therein, which are not limited in any way by the embodiments of the present disclosure.

As shown in fig. 3, OLT 300 includes an optical transceiver 310 and a controller 320. The optical transceiver 310 may be implemented as or as part of the optical transceiver 121 of fig. 1. The controller 320 may be implemented as, or as part of, the controller 122 of fig. 1. For convenience, the following description will be made in conjunction with the example system shown in fig. 1. It should be understood that embodiments of the present disclosure may be utilized in other suitable environments or systems either currently known or later developed in the future.

As shown in fig. 3, the optical transceiver 310 may include a receiver 311. The optical transceiver 310 may include other additional components not shown, which are not intended to be limiting in any way by the disclosed embodiments. The receiver 311 may be implemented as, or as part of, the receiver 142 of fig. 1. The receiver 311 may include a photodetector 331 and an amplifier 332. It should be understood that the receiver 311 may include other additional components not shown or omit some components shown therein, which the disclosed embodiments do not limit in any way.

The optical detector 331 is configured to receive the optical signal from the ONU 110. In some embodiments, the optical detector 331 may further convert the received optical signal into a current signal and provide the current signal to an amplifier 332 coupled to the optical detector 331. The amplifier 332 is configured to receive an indication signal MODE from the controller 320, wherein the indication signal MODE is used for indicating an operation MODE of the controller 320. In this manner, the amplifier 332 is informed of the operating mode of the controller 320 in real time, thereby adjusting its operation appropriately.

The operation mode of the controller 320 may be a windowing mode or a data transceiving mode. In the context of the present disclosure, "windowing mode" means that the controller 320 allocates a specific time slot for ONUs to be brought online in order to receive optical signals from the ONUs and perform ranging processing, thereby completing registration of the ONUs to be brought online. The "data transceiving mode" refers to that the controller 320 allocates a specific bandwidth to the ONU that has been registered on line according to the system configuration, so as to perform data transmission. Of course, the disclosed embodiments are not so limited and the controller 320 may also include other existing or future-developed modes of operation.

In some embodiments, the amplifier 332 may receive the indication signal from the controller 320 via the first input-output terminal of the optical transceiver 310. In some embodiments, the first input-output terminal may be one or more pins. Of course, other forms of first input-output terminals are also possible. In some embodiments, the first input-output terminal may be dedicated to indicating reception of the signal MODE, as shown in fig. 3. In this way, accurate reception of the indication signal MODE is facilitated.

In some alternative embodiments, the first input-output terminal may be a terminal that is multiplexed with other signals. For example, the indication signal MODE may multiplex one terminal with the RESET signal RESET. As another example, the indication signal MODE may be multiplexed with a rate selection signal (not shown in the figure) by one terminal. It should be noted here that the embodiments of the present disclosure are not limited thereto, and the indication signal MODE may be multiplexed with any other suitable signal or signals by one terminal. Through the multiplexing of the terminal, the change of the hardware structure of the optical transceiver can be reduced, and the cost is reduced.

The amplifier 332 is further configured to adjust an optical processing parameter of the receiver 311 for the optical signal based on the indication signal MODE. In some embodiments, the amplifier 332 may determine an operating MODE of the controller 320 based on the indication signal MODE and adjust the light processing parameters for the light signal based on the operating MODE. In some embodiments, the characteristics of the indication signal MODE are used to indicate the operating MODE of the controller 320. For example, the characteristic indicating signal MODE may be the amplitude, frequency, phase, etc. of the signal. It is to be understood that the above examples of features are merely illustrative and not restrictive, and that other suitable features are possible.

In some embodiments, when the indication signal MODE is at a first level, the amplifier 332 may determine that the operation MODE of the controller 122 is the windowing MODE, and when the indication signal MODE is at a second level different from the first level, the amplifier 332 may determine that the operation MODE of the controller 122 is the data transceiving MODE. For example, the first level and the second level may differ in at least one of amplitude, frequency, and phase.

In some embodiments, the first level and the second level have different amplitude values. For convenience of description, the amplitude value that the first level has will be hereinafter referred to as "first amplitude value", and the amplitude value that the second level has will be hereinafter referred to as "second amplitude value". The first amplitude value may be greater than or less than the second amplitude value.

Alternatively or additionally, in some embodiments, the first level and the second level have different durations. For convenience of description, the duration that the first level has will be hereinafter referred to as "first duration", and the duration that the second level has will be hereinafter referred to as "second duration". The first duration may be greater than or less than the second duration. It should be understood that the above-described embodiments are merely examples, and the disclosed embodiments are not limited thereto, as any other suitable manner is possible.

If the indication signal MODE indicates that the operation MODE of the controller 320 is the windowing MODE, the amplifier 332 may adjust the light processing parameters in a variety of ways. For example, in some embodiments, the amplifier 332 may adjust the optical processing parameters by adjusting a gain parameter. Alternatively or additionally, the amplifier 332 may also adjust the bias voltage. As another example, in some instances, coupling capacitor bias voltages may be adjusted, dc bias removed, and so forth. Note that these adjustment means may be used alone or in combination.

By way of example, amplifier 332 may be implemented to include a pre-amplifier and a post-amplifier. The pre-amplifier may comprise, for example, a TIA and the post-amplifier may comprise, for example, a LA. In these embodiments, the amplifier 332 may adjust the gain parameter and bias voltage of the preamplifier according to the intensity of the current signal output by the optical detector 331. In this way, the dc decision voltage can be quickly adjusted and an appropriate gain selected, generating an amplified voltage signal. In turn, the amplifier 332 may adjust the coupling capacitor voltage of the post-amplifier and cancel the dc offset. Thus, the amplified voltage signal can be converted into a standard digital level signal as the reception data output RX of the optical transceiver 310. For example only, the standard digital level Signal may conform to various standard digital level formats such as Current Mode Logic (CML), positive Emitter Coupled Logic (PECL), low Voltage Differential Signaling (LVDS). It is to be understood that this is by way of example only and is not limiting. The standard digital level signal may conform to any other standard digital level format known in the art or determined in the future.

It should be noted here that the configuration of the amplifier 332 is not limited to the above example, but may be implemented in any other suitable manner. Accordingly, the operation of adjusting the light processing parameters is not limited to the above example, and any other suitable operation is possible.

By adjusting the optical processing parameters based on the indication signal, the optical signal of the ONU can be correctly processed even in the windowing mode. Therefore, the occurrence of the dead cycle is avoided, and the registration of the ONU is ensured to be realized. In addition, since the optical transceiver can know the current operating mode in time, the design complexity of the optical transceiver, particularly the amplifier, can be reduced. And then can reduce the size of optical transceiver, be convenient for the high integration of OLT.

In some alternative embodiments, if the indication signal MODE indicates that the operation MODE of the controller 320 is the windowing MODE, the amplifier 332 may directly RESET the receiver 311 without the RESET signal RESET from the controller 320. In some embodiments, the amplifier 332 may autonomously generate a reset signal to directly reset the receiver 311. Of course, any other suitable manner for directly resetting the receiver 311 may be used. Resetting the receiver 311 refers to adjusting the optical processing parameters of the receiver 311 to predetermined values. In some embodiments, the predetermined value may be predetermined. In other embodiments, the predetermined value may be dynamically determined as desired. The embodiments of the present disclosure are not limited in any way with respect to the specific implementation of the reset. In this way, adjustments to the light processing parameters can be made more easily and quickly.

In some embodiments, after the adjustment of the optical processing parameters, the amplifier 332 may provide the converted standard digital level signal as the received data output RX to the controller 320 for further processing. Additionally or alternatively, the amplifier 332 may also output a detection signal SD to the controller 320 for indicating that the optical transceiver 310 has received an optical signal. Further, the amplifier 332 may receive a RESET signal RESET from the controller 320, which is generated based on the detection signal SD and is used to instruct to RESET the receiver 311. In this way, the receiver 311 may be subsequently brought into normal operation.

In some embodiments, if the indication signal MODE indicates that the operation MODE of the controller 320 is the data transceiving MODE, the amplifier 332 may RESET the receiver 311 based on the RESET signal RESET from the controller 320. In this way, the receiver 311 can process the optical signal from the ONU 110 for data transmission.

Referring also to fig. 3, the controller 320 may include a first signal generator 321. The first signal generator 321 is configured to generate the indication signal MODE. In some embodiments, the first signal generator 321 may determine whether the operation MODE of the controller 320 is the windowing MODE or the data transceiving MODE, and generate the indication signal MODE to indicate the operation MODE. For example, in some embodiments, if the operation MODE of the controller 320 is switched from the data transceiving MODE to the windowing MODE, the first signal generator 321 may generate the indication signal MODE to indicate that the operation MODE is the windowing MODE. If the operation MODE of the controller 320 is switched from the windowing MODE to the data transceiving MODE, an indication signal MODE is generated to indicate that the operation MODE is the data transceiving MODE. In this way, the generation of the indication signal MODE can be conveniently realized.

In some embodiments, the first signal generator 321 may indicate the operation MODE of the controller 320 by indicating a characteristic of the signal MODE. For example, the characteristic indicating signal MODE may be the amplitude, frequency, phase, etc. of the signal. It should be understood that the above examples of features are merely illustrative and not restrictive, and that other suitable features are possible.

In some embodiments, if it is determined that the operation MODE of the controller 320 is the windowing MODE, the first signal generator 321 may generate the indication signal MODE having a first level to indicate the windowing MODE. If it is determined that the operation MODE of the controller 320 is the data transceiving MODE, the first signal generator 321 may generate the indication signal MODE having a second level different from the first level to indicate the data transceiving MODE. For example, the first level and the second level may differ in at least one of amplitude, frequency, and phase.

Following the previous example, the first level has a first amplitude value and a first duration, and the second level has a second amplitude value and a second duration. In some embodiments, the first amplitude value of the first level may be made greater than the second amplitude value of the second level. Alternatively, the first amplitude value may be made smaller than the second amplitude value. In some alternative or additional embodiments, the first duration of the first level may be made greater than the second duration of the second level. Of course, it is also possible that the first duration is smaller than the second duration. The embodiments described above are merely examples, and the embodiments of the present disclosure are not limited thereto, and any other suitable feature or combination of features is possible.

The first signal generator 321 may also be configured to provide the indication signal MODE to the optical transceiver 310. In some embodiments, the first signal generator 321 may provide the indication signal MODE to the optical transceiver 310 via the second input/output terminal of the controller 320. In some embodiments, the second input-output terminal may be one or more pins. It should be understood that other forms of second input-output terminals are also possible. In some embodiments, the second input-output terminal may be dedicated to the provision of the indication signal MODE, as shown in fig. 3. In this way, accurate provision of the indication signal MODE can be facilitated.

In some alternative embodiments, the second input-output terminal may be a terminal multiplexed with other signals. For example, the indication signal MODE may multiplex one terminal with the RESET signal RESET. As another example, the indication signal MODE may be multiplexed with a rate selection signal (not shown in the figure) by one terminal. It should be understood that the embodiments of the present disclosure are not limited thereto, but rather indicate that the signal MODE may multiplex one terminal with any other suitable signal or signals. Through the multiplexing of the terminal, the change of the hardware structure of the controller can be reduced, and the cost is reduced.

Additionally, the controller 320 may further include a second signal generator (not shown in the figures). The second signal generator may be configured to receive the detection signal SD from the optical transceiver 310 and generate the RESET signal RESET based on the detection signal SD. In addition, the second signal generator may provide the RESET signal RESET to the optical transceiver 320 for resetting the receiver 311 of the optical transceiver 310.

In the above manner, by notifying the optical transceiver 310 of the operation mode of the controller 320, the controller 320 can obtain the ONU optical signals accurately processed by the optical transceiver 310. In this way, the stability and accuracy of optical signal processing on the OLT side can be improved. In addition, the complexity of the optical receiving process on the OLT side can be reduced, and the high integration of the OLT can be promoted. Accordingly, embodiments of the present disclosure also provide optical signal processing methods implemented at the optical transceiver and at the controller, which are described below in conjunction with fig. 4-6.

Fig. 4 shows a flow diagram of an optical signal processing method 400 according to one embodiment of the present disclosure. The method may be implemented at an OLT-side optical transceiver (e.g., optical transceiver 121 of fig. 1 or optical transceiver 310 of fig. 3), such as receiver 142 of fig. 1 or receiver 311 of fig. 3. For convenience, fig. 4 is described below in connection with the example of fig. 3. It should be understood that the method of fig. 4 may include other additional steps not shown, or may omit some of the steps shown. The scope of the present disclosure is not limited thereto.

As shown in fig. 4, at block 401, an optical transceiver 310 receives an optical signal from an ONU 110. In some embodiments, the optical transceiver 310 may receive time division multiplexed optical signals from multiple ONUs 110. The disclosed embodiments are not so limited. In some alternative embodiments, the optical transceiver 310 may also receive optical signals from a single ONU 110.

At block 402, the optical transceiver 310 receives an indication signal MODE from the controller 320, which indicates the operating MODE of the controller 320. In some embodiments, the operating modes of the controller 320 may include a windowing mode and a data transceiving mode. The windowing mode means that the controller allocates a specific time slot for the ONUs to be online so as to receive optical signals from the ONUs and perform ranging processing, thereby completing the online registration of the ONUs. The data transceiving mode refers to that the controller 320 allocates a specific bandwidth to the ONU which is registered to be on-line according to the system configuration, so as to perform data transmission. It should be understood that the disclosed embodiments are not so limited and that the controller 320 may include other existing or future-developed modes of operation.

According to some embodiments of the present disclosure, the optical transceiver 310 may receive the indication signal from the controller 320 via a first input-output terminal of the optical transceiver 310. In some embodiments, the first input-output terminal may be one or more pins. Of course, other forms of first input-output terminals are also possible. In some embodiments, the first input-output terminal may be dedicated to indicating reception of the signal MODE. In this way, accurate reception of the indication signal may be facilitated.

In some alternative embodiments, the first input-output terminal may be a terminal that is multiplexed with other signals. For example, the indication signal MODE may multiplex one terminal with the RESET signal RESET. As another example, the indication signal MODE may multiplex one terminal with a rate selection signal (not shown in the figure). It should be understood that the embodiments of the present disclosure are not limited thereto, but rather indicate that the signal MODE may multiplex one terminal with any other suitable signal or signals. Through the multiplexing of the terminal, the change of the hardware structure of the optical transceiver can be reduced, and the cost is reduced.

At block 403, based on the indication signal MODE, the optical transceiver 310 adjusts optical processing parameters of the receiver 311 in the optical transceiver 310 for the optical signal. According to some embodiments of the present disclosure, the optical transceiver 310 may determine the operating MODE of the controller 320 based on the indication signal MODE. Based on the determined mode of operation, the optical transceiver 310 may adjust optical processing parameters. In this way, the optical transceiver 310 can know the operating mode of the controller 320, and thus can adjust the optical processing parameters in time to process the optical signals received from the ONU 110. This is explained in more detail below in conjunction with fig. 5.

Fig. 5 shows a flow diagram of a method 500 of adjusting light processing parameters according to one embodiment of the present disclosure. The method of fig. 5 may be implemented at an optical transceiver (e.g., optical transceiver 121 of fig. 1 or optical transceiver 310 of fig. 3) on the OLT side, such as receiver 142 of fig. 1 or receiver 311 of fig. 3. For convenience, FIG. 5 is described below in connection with the example of FIG. 3. It should be understood that the method of fig. 5 may include other additional steps not shown, or may omit some of the steps shown. The scope of the present disclosure is not limited thereto.

As shown in fig. 5, at block 501, the optical transceiver 121 may determine whether the operation MODE of the controller 320 is the windowing MODE or the data transceiving MODE based on the indication signal MODE. In some embodiments, the optical transceiver 310 may determine the operating MODE of the controller 320 based on characteristics indicative of the signal MODE. For example, the characteristics indicating the signal MODE may include amplitude, frequency, phase, and the like. It should be understood that this is by way of example only and that other features are possible.

In some embodiments, when the indication signal MODE is at a first level, the optical transceiver 310 may determine that the operation MODE of the controller 320 is the windowing MODE. When the indication signal MODE is at a second level different from the first level, the optical transceiver 310 may determine that the operation MODE of the controller 320 is the data transceiving MODE. For example, the first level and the second level may differ in at least one of amplitude, frequency, and phase.

Continuing with the previous example, the first level has a first amplitude value and a first duration and the second level has a second amplitude value and a second duration. In some embodiments, the first amplitude value of the first level may be greater than the second amplitude value of the second level. Alternatively, the first amplitude value may be smaller than the second amplitude value. In some alternative or additional embodiments, the first duration of the first level may be greater than the second duration of the second level. Alternatively, the first duration may also be less than the second duration. It should be understood that the above-described embodiments are merely examples, and the disclosed embodiments are not limited thereto, and any other suitable feature or combination of features is possible.

If the operating mode is determined to be windowed at block 501, the optical transceiver 310 may adjust optical processing parameters of the receiver 311 at block 502. For example, the optical processing parameters may include gain parameters, bias voltages, coupling capacitor voltages, dc bias, and the like. In some embodiments, the optical transceiver 310 may adjust the gain parameter to adjust the optical processing parameter. Alternatively or additionally, the optical transceiver 310 may also adjust the bias voltage. As another example, in some instances, coupling capacitor bias voltages may be adjusted, dc bias eliminated, and so forth. Note that these adjustment means may be used alone or in combination. Of course, this is merely an example, and any other suitable operation is possible.

For example, in some embodiments, if the indication signal MODE indicates that the operation MODE of the controller 320 is the windowing MODE, the optical transceiver 310 may adjust the bias voltage and the gain parameter of the pre-amplifier (e.g., TIA) in the amplifier 332 according to the intensity of the current signal converted by the optical detector 331. In this way, a fast adjustment of the dc decision voltage and selection of a suitable gain are enabled, generating an amplified voltage signal. Alternatively or additionally, the optical transceiver 310 may adjust the coupling capacitance voltage of a post-amplifier (e.g., LA) in the amplifier 332 and eliminate the dc bias. Thus, the amplified voltage signal can be converted into a standard digital level signal as the reception data output RX of the optical transceiver 310. The standard digital level signal may conform to various standard digital level formats such as CML, PECL, LVDS, etc. It should be understood that the standard digital level signal is presented here by way of example only and not by way of limitation and may conform to any other standard digital level format known in the art or determined in the future.

By adjusting the optical processing parameters based on the indication signal, the optical signal of the ONU can be correctly processed even in the windowing mode. Therefore, the occurrence of the dead cycle is avoided, and the registration of the ONU is ensured to be on line. In addition, since the optical transceiver can know the current operating mode in time, the design complexity of the optical transceiver, particularly the amplifier, can be reduced. And then can reduce the size of optical transceiver, be convenient for the high integration of OLT.

In some alternative embodiments, the optical transceiver 310 may reset the receiver 311 if the indication signal MODE indicates that the operating MODE of the controller 320 is the windowing MODE. In this case, the receiver 311 may be RESET without receiving a RESET signal RESET from the controller 320, thereby processing the optical signal from the ONU 110. In some embodiments, the optical transceiver 310 may autonomously generate a reset signal to reset the receiver 311. Of course, any other suitable manner of resetting the receiver 311 may be used. As mentioned previously, resetting the receiver 311 refers to adjusting the light processing parameters of the receiver 311 to predetermined values. In some embodiments, the predetermined value may be predetermined. In some embodiments, the predetermined value may be dynamically determined as needed. The adjustment of the light processing parameters can be realized more simply, conveniently and rapidly by direct reset.

As a result of the adjustment of the optical processing parameters described above, the optical transceiver 310 may provide a detection signal SD to the controller 320 at block 503 for indicating that the optical transceiver 310 has received an optical signal. In some embodiments, the optical transceiver 310 may also provide the standard digital level signal as a receive data output RX to the controller 320 for further processing.

At block 504, the optical transceiver 310 may receive a RESET signal RESET from the controller 320. The RESET signal RESET is generated based on the detection signal SD and is used to instruct to RESET the receiver 311. Thereby, the stability of optical signal processing in the windowing mode of OLT 300 can be ensured, avoiding the occurrence of dead cycles.

If the operating mode is determined to be the data transceiving mode at 501, the optical transceiver 310 may RESET the receiver 311 based on a RESET signal RESET from the controller 320 at block 505. In this way, the receiver 311 can process the optical signal from the ONU 110 for data transmission.

The optical signal processing method implemented at the optical transceiver according to the embodiment of the present disclosure is described above with reference to fig. 4 and 5, and the optical signal processing method implemented at the controller according to the embodiment of the present disclosure is described below with reference to fig. 6. FIG. 6 shows a flow diagram of an optical signal processing method 600 according to one embodiment of the present disclosure. The method may be implemented at a controller (e.g., controller 122 of fig. 1 or controller 320 of fig. 3) at the OLT side. For convenience, FIG. 6 is described below in connection with the example of FIG. 3. It should be understood that the method of fig. 6 may include other additional steps not shown, or may omit some of the steps shown, as the scope of the present disclosure is not limited in this respect.

As shown in fig. 6, at block 601, the controller 320 generates an indication signal MODE for indicating the operation MODE of the controller 320. In some embodiments, the operation mode of the controller 320 is a windowing mode or a data transceiving mode. In some embodiments, the controller 320 may determine whether the operation MODE is the windowing MODE or the data transceiving MODE, and generate the indication signal MODE to indicate the operation MODE. For example, in some embodiments, if the operation MODE is switched from the data transceiving MODE to the windowing MODE, the controller 320 may generate an indication signal MODE to indicate that the operation MODE is the windowing MODE. If the operation MODE is switched from the windowing MODE to the data transceiving MODE, the controller 320 generates an indication signal MODE to indicate that the operation MODE is the data transceiving MODE.

In some embodiments, the controller 320 can indicate its operating MODE by indicating a characteristic of the signal MODE. The characteristics of the indicator signal may include amplitude, frequency, phase, and the like. It should be understood that this is by way of example only and that other features are possible. In some embodiments, if it is determined that the operation MODE is the windowing MODE, the controller 320 may generate the indication signal MODE having the first level to indicate the windowing MODE. If it is determined that the operation MODE is the data transceiving MODE, the controller 320 may generate the indication signal MODE having a second level different from the first level to indicate the data transceiving MODE. For example, the first level and the second level may differ in at least one of amplitude, frequency, and phase.

At block 602, the controller 320 may provide the indication signal MODE to the optical transceiver 310. Thereby, the optical transceiver 310 is caused to adjust the optical processing parameters of the receiver 311 of the optical transceiver 310 based on the indication signal MODE. In some embodiments, the controller 320 may provide the indication signal MODE to the optical transceiver 310 via the second input-output terminal. In some embodiments, the second input-output terminal may be one or more pins. Of course, other forms of second input-output terminals are also possible. In some embodiments, the second input-output terminal may be dedicated to the provision of the indication signal MODE, as shown in fig. 3. In this way, accurate provision of the indication signal MODE can be facilitated.

In some alternative embodiments, the second input-output terminal may be a terminal multiplexed with other signals. For example, the indication signal MODE may multiplex one terminal with the RESET signal RESET. As another example, the indication signal MODE may multiplex one terminal with a rate selection signal (not shown in the figure). It should be understood that the embodiments of the present disclosure are not limited thereto, but rather indicate that the signal MODE may multiplex one terminal with any other suitable signal or signals. Through the multiplexing of the terminal, the change of the hardware structure of the controller can be reduced, and the cost is reduced.

In some alternative or additional embodiments, the controller 320 may also receive a detection signal SD from the optical transceiver 310 and generate a RESET signal RESET based on the detection signal SD. In turn, the controller 320 may provide the RESET signal RESET to the optical transceiver 320 for resetting the receiver 311 of the optical transceiver 310.

According to the method of the embodiment of the present disclosure, by notifying the optical transceiver 310 of the operation mode of the controller 320, the controller 320 may obtain the ONU optical signals accurately processed by the optical transceiver 310. In this way, the stability and accuracy of the OLT-side light reception process can be improved. In addition, the design complexity of the optical transceiver can be reduced, and the high integration of the OLT is promoted.

The optical signal processing method, the optical transceiver, the controller, and the OLT according to the embodiment of the present disclosure have been described so far with examples. In a method according to an embodiment of the present disclosure, an indication signal indicating an operation mode thereof is generated by a controller and provided to an optical transceiver. The optical transceiver receives the indication signal and, upon receiving the optical signal from the ONU, adjusts an optical processing parameter for the optical signal based on the indication signal. Accordingly, an OLT according to an embodiment of the present disclosure includes an optical transceiver and a controller. The optical transceiver includes a receiver that may include a photodetector and an amplifier coupled to the photodetector. The optical detector is configured to receive the optical signal from the ONU, and the amplifier is configured to receive an indication signal from the controller for indicating an operation mode of the controller and to adjust an optical processing parameter of the receiver for the optical signal based on the indication signal. The controller includes a first signal generator configured to generate the indication signal and provide the indication signal to the optical transceiver. According to the scheme of the embodiment of the disclosure, the stability and the accuracy of the OLT side light receiving processing can be ensured. In addition, the design complexity of the optical transceiver, particularly the amplifier, can be reduced, and the high integration of the OLT can be promoted.

In general, the various example embodiments of this disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While aspects of embodiments of the disclosure have been illustrated or described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. Examples of hardware devices that may be used to implement embodiments of the present disclosure include, but are not limited to: field Programmable Gate Arrays (FPGAs), application-Specific Integrated circuits (ASICs), application-Specific Standard products (ASSPs), system On a Chip (SOCs), complex Programmable Logic Devices (CPLDs), and so forth.

By way of example, embodiments of the disclosure may be described in the context of machine-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or divided between program modules as described. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed facility, program modules may be located in both local and remote memory storage media.

Computer program code for implementing the methods of the present disclosure may be written in one or more programming languages. These computer program codes may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the computer or other programmable data processing apparatus, cause the functions/acts specified in the flowchart and/or block diagram block or blocks to be performed. The program code may execute entirely on the computer, partly on the computer, as a stand-alone software package, partly on the computer and partly on a remote computer or entirely on the remote computer or server.

In the context of the present disclosure, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations described above. Examples of a carrier include a signal, computer readable medium, and the like.

Examples of signals may include electrical, optical, radio, acoustic, or other forms of propagated signals, such as carrier waves, infrared signals, and the like.

A machine-readable medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More detailed examples of a machine-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, 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 storage device, a magnetic storage device, or any suitable combination thereof.

Additionally, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking or parallel processing may be beneficial. Likewise, while the above discussion contains certain specific implementation details, this should not be construed as limiting the scope of any invention or claims, but rather as describing particular embodiments that may be directed to particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. An optical signal processing method, comprising:

the optical transceiver receives an optical signal from the optical network unit;

the optical transceiver receives an indication signal from a controller, wherein the indication signal is used for indicating the working mode of the controller; and

if the indication signal indicates that the working mode of the controller is a windowing mode, the optical transceiver adjusts optical processing parameters of a receiver of the optical transceiver aiming at the optical signal so as to process the optical signal;

the windowing mode is that the controller allocates a specific time slot for the optical network unit to be on-line, so that the optical transceiver receives an optical signal from the optical network unit to be on-line and performs ranging processing to complete registration on-line of the optical network unit to be on-line.

2. The method of claim 1, wherein the optical transceiver adjusting the optical processing parameters comprises:

based on the indication signal, the optical transceiver determining an operating mode of the controller; and

based on the operating mode, the optical transceiver adjusts the optical processing parameters.

3. The method of claim 1, wherein a characteristic of the indicator signal is used to indicate an operating mode of the controller, the characteristic comprising at least one of amplitude, frequency, and phase.

4. The method of claim 1, wherein an operating mode of the controller is the windowing mode or a data transceiving mode.

5. The method of any of claims 1-4, wherein the optical transceiver adjusting the optical processing parameters comprises:

if the indication signal indicates that the working mode of the controller is the windowing mode, performing at least one of the following:

adjusting a gain parameter of the receiver;

adjusting a bias voltage of the receiver;

adjusting a coupling capacitance bias voltage of the receiver; and

and eliminating the direct current bias of the receiver.

6. The method of any of claims 1-4, the optical transceiver to adjust the optical processing parameters comprising:

resetting the receiver.

7. The method of any of claims 1-4, further comprising:

and if the indication signal indicates that the working mode of the controller is a data transceiving mode, resetting the receiver based on a reset signal from the controller.

8. The method of any of claims 1-4, wherein the optical transceiver receiving the indication signal comprises:

the optical transceiver receives the indication signal from the controller via a first input-output terminal of the optical transceiver.

9. The method of claim 8, wherein the first input-output terminal is dedicated to reception of the indication signal.

10. The method of any of claims 1-4, further comprising:

the optical transceiver providing a detection signal to the controller, the detection signal indicating that the optical transceiver has received the optical signal; and

the optical transceiver receives a reset signal from the controller, the reset signal being generated by the controller based on the detection signal, the reset signal being used to reset the receiver.

11. An optical signal processing method, comprising:

the method comprises the steps that a controller generates an indication signal, and the indication signal is used for indicating the working mode of the controller; and

the controller provides the indication signal to an optical transceiver so that the optical transceiver adjusts optical processing parameters of a receiver of the optical transceiver when the indication signal indicates that the working mode of the controller is a windowing mode to process an optical signal;

12. The method of claim 11, wherein the controller generating the indication signal comprises:

determining whether the operating mode of the controller is the windowing mode or the data transceiving mode; and

generating the indication signal to indicate an operating mode of the controller.

13. The method of claim 11, wherein a characteristic of the indicator signal is used to indicate an operating mode of the controller, the characteristic including at least one of amplitude, frequency, and phase.

14. The method of any of claims 11-13, wherein the controller generating the indication signal comprises:

if the working mode of the controller is switched to the windowing mode from the data receiving and transmitting mode, generating the indicating signal to indicate that the working mode is the windowing mode; and

and if the working mode of the controller is switched to the data transceiving mode from the windowing mode, generating the indication signal to indicate that the working mode is the data transceiving mode.

15. The method of any of claims 11-13, wherein the controller providing the indication signal comprises:

providing the indication signal to the optical transceiver via a second input-output terminal of the controller.

16. The method of claim 15, wherein the second input-output terminal is dedicated to the provision of the indication signal.

17. The method according to any one of claims 11-13, further comprising:

the controller receives a detection signal from the optical transceiver indicating that the optical transceiver has received the optical signal; and

the controller provides a reset signal to the optical transceiver, the reset signal being generated by the controller based on the detection signal, the reset signal being used to reset the receiver.

18. An optical transceiver, comprising:

a receiver, the receiver comprising:

a light detector configured to receive an optical signal from an optical network unit;

an amplifier coupled with the light detector and configured to:

receiving an indication signal from a controller, wherein the indication signal is used for indicating the working mode of the controller; and

if the indication signal indicates that the working mode of the controller is a windowing mode, adjusting the optical processing parameters of the receiver aiming at the optical signal so as to process the optical signal;

19. The optical transceiver of claim 18, wherein the amplifier is further configured to:

determining an operating mode of the controller based on the indication signal; and

adjusting an optical processing parameter of the receiver based on the operating mode.

20. The optical transceiver of claim 18, wherein a characteristic of the indication signal is used to indicate an operating mode of the controller, the characteristic comprising at least one of amplitude, frequency, and phase.

21. The optical transceiver of claim 18, wherein the controller operates in the windowing mode or a data transceiving mode.

22. The optical transceiver of any of claims 18-21, wherein the amplifier is further configured to:

adjusting a gain parameter of the receiver;

adjusting a bias voltage of the receiver;

adjusting a coupling capacitance bias voltage of the receiver; and

and eliminating the DC offset of the receiver.

23. The optical transceiver of any of claims 18-21, wherein the amplifier is further configured to:

resetting the receiver.

24. The optical transceiver of any of claims 18-21, wherein the amplifier is further configured to:

resetting the receiver based on a reset signal from the controller if the indication signal indicates that the operating mode of the controller is a data transceiving mode.

25. The optical transceiver of any of claims 18-21, wherein the amplifier is further configured to:

receiving the indication signal from the controller via a first input-output terminal of the optical transceiver.

26. The optical transceiver of claim 25, wherein the first input-output terminal is dedicated to reception of the indication signal.

27. The optical transceiver of any of claims 18-21, wherein the amplifier is further configured to:

providing a detection signal to the controller, the detection signal indicating that the optical transceiver has received the optical signal, an

Receiving a reset signal from the controller, the reset signal generated by the controller in response to the detection signal, the reset signal to reset the receiver.

28. The optical transceiver of any of claims 18-21, wherein the amplifier comprises a pre-amplifier and a post-amplifier.

29. A controller, comprising:

a first signal generator configured to:

generating an indication signal for indicating an operating mode of the controller; and

providing the indication signal to an optical transceiver to cause the optical transceiver to adjust an optical processing parameter of a receiver in the optical transceiver to process an optical signal when the indication signal indicates that the operating mode of the controller is the windowed mode;

30. The controller of claim 29, wherein the first signal generator is further configured to:

31. The controller of claim 29, wherein a characteristic of the indicator signal is used to indicate an operating mode of the controller, the characteristic including at least one of amplitude, frequency, and phase.

32. The controller of any one of claims 29-31, wherein the first signal generator is further configured to:

and if the working mode of the controller is switched to a data transceiving mode from the windowing mode, generating the indication signal to indicate that the working mode is the data transceiving mode.

33. The controller of any one of claims 29-31, wherein the first signal generator is further configured to:

34. The controller of claim 33, wherein the second input-output terminal is dedicated to the provision of the indication signal.

35. The controller of any of claims 29-31, further comprising:

a second signal generator configured to:

receiving a detection signal from the optical transceiver, the detection signal indicating that the optical transceiver has received an optical signal; and

providing a reset signal to the optical transceiver, the reset signal generated based on the detection signal, the reset signal to reset the receiver.

36. An optical line terminal comprising:

the optical transceiver of any of claims 18-28; and

a controller according to any of claims 29-35.