CN113055097B

CN113055097B - Coherent reception method, signal processing method and system

Info

Publication number: CN113055097B
Application number: CN201911378406.2A
Authority: CN
Inventors: 杨波; 张伟良; 黄新刚; 钟一鸣; 郭勇; 袁立权
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2024-05-14
Anticipated expiration: 2039-12-27
Also published as: CN113055097A

Abstract

The embodiment of the invention discloses a coherent receiving method, a signal processing method and a system, wherein the coherent receiving method comprises the following steps: transmitting a downlink message to an Optical Network Unit (ONU), wherein the downlink message is used for triggering the ONU to adjust signal transmission parameters; and in response to receiving the adjusted optical signal, performing coherent mixing processing on the optical signal and an intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal with a frequency value within an intermediate frequency allowable value range.

Description

Coherent reception method, signal processing method and system

Technical Field

The embodiment of the invention relates to the technical field of optical access, in particular to a coherent receiving method, a signal processing method and a system.

Background

With the development of network technology, the demand for network bandwidth for transmitting a large amount of data by using a network is continuously increasing, the capacity of an optical fiber transmission access network is continuously increasing, 10G passive optical network (Passive Optical Network, PON) technology is gradually coming into commercial use, and a 50G PON or higher-rate PON system will become the direction of development of a next-generation PON system in the future.

In a passive optical network (Passive Optical Network, PON) system based on an intensity modulation direct detection technique, a coherent reception technique is an effective technical means for improving the optical power budget of the system.

In PON networks, when Optical line terminals (Optical LINE TERMINAL, OLT) perform coherent reception on Optical signals from an Optical network unit (Optical Network Unit, ONU), a frequency difference between the intrinsic light and the uplink signal light (i.e., a frequency value of an intermediate frequency signal) easily exceeds a coherent mixing range due to uncertainty of wavelengths of the intrinsic light and the signal light, so that a problem of signal detection failure is caused.

Disclosure of Invention

The embodiment of the invention provides a coherent receiving method, a signal processing method and a system, which can realize high-sensitivity coherent receiving in a passive optical network system.

In a first aspect, an embodiment of the present invention provides a coherent receiving method, which is used for an optical line terminal OLT, including: transmitting a downlink message to an Optical Network Unit (ONU), wherein the downlink message is used for triggering the ONU to adjust signal transmission parameters; and in response to receiving the adjusted optical signal, performing coherent mixing processing on the optical signal and an intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal with a frequency value within an intermediate frequency allowable value range.

In a second aspect, an embodiment of the present invention provides a signal processing method, configured to be used in an optical network unit ONU, including: adjusting signal emission parameters of the optical signals in response to receiving the downlink message from the optical line terminal OLT; and transmitting an optical signal to the OLT according to the adjusted signal transmission parameters, so that after the optical signal and the intrinsic optical signal are subjected to coherent mixing processing, an intermediate frequency signal with a frequency value within an intermediate frequency allowable value range is obtained.

In a third aspect, an embodiment of the present invention provides an optical line terminal, including: the medium access controller module is used for sending a downlink message to the Optical Network Unit (ONU), and the downlink message is used for triggering the ONU to adjust signal transmission parameters; and the signal receiving module is used for performing coherent mixing processing on the optical signal and the intrinsic optical signal in response to receiving the adjusted optical signal to obtain an intermediate frequency signal with a frequency value within an intermediate frequency allowable range.

In a fourth aspect, an embodiment of the present invention provides an optical network unit, including: the emission parameter regulation module is used for responding to the received downlink message from the optical line terminal OLT and adjusting the signal emission parameter of the optical signal; and the signal transmitting module is used for transmitting the optical signal to the OLT according to the adjusted signal transmitting parameter so as to obtain an intermediate frequency signal with the frequency value within the intermediate frequency allowable range after the optical signal and the intrinsic optical signal are subjected to coherent mixing processing.

In a fifth aspect, an embodiment of the present invention provides an optical network system, including an OLT and an optical network unit ONU, where the OLT is configured to send a downlink message to the ONU, and the downlink message is used to trigger the ONU to adjust a signal transmission parameter; the ONU is used for responding to the received downlink message, adjusting the signal transmission parameters of the optical signals and sending the optical signals to the OLT according to the adjusted signal transmission parameters; and the OLT is also used for carrying out coherent mixing processing on the received optical signal and the intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal with the frequency value within the intermediate frequency allowable value range.

In a sixth aspect, an embodiment of the present invention provides a coherent receiving system, including: a memory and a processor; the memory is used for storing programs; the processor is configured to read executable program code stored in the memory to perform the coherent reception method described above.

In a seventh aspect, an embodiment of the present invention provides a signal processing system, including: a memory and a processor; the memory is used for storing programs; the processor is configured to read executable program code stored in the memory to perform the signal processing method described above.

According to the coherent receiving method, the signal processing method and the system, the wavelength of the transmitted signal light in the ONU can be adjusted and calibrated on line, so that the problem that the working wavelength of an uplink optical network unit in a passive optical network system is uncertain and exceeds the intermediate frequency receiving range of an OLT coherent receiver is solved.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention.

Fig. 1 is a schematic diagram of a topology of a passive optical network according to an embodiment of the present invention.

Fig. 2 shows a flowchart of a coherent reception method according to an embodiment of the present invention.

Fig. 3a shows a schematic diagram of an ONU adjusting the wavelength of an optical signal in an embodiment.

Fig. 3b shows a schematic diagram of an ONU adjusting the wavelength of an optical signal in another embodiment.

Fig. 4 is a schematic diagram showing a time-dependent change curve of an ac power value in an embodiment of the present invention.

Fig. 5 shows a flow chart of a signal processing method according to another embodiment of the invention.

Fig. 6 illustrates a schematic structure of an optical line terminal according to an embodiment of the present invention.

Fig. 7 shows a schematic structural diagram of an optical network unit according to an embodiment of the present invention.

Fig. 8 shows a schematic structural diagram of an optical network system according to an embodiment of the present invention.

Fig. 9 is a block diagram illustrating an exemplary hardware architecture capable of implementing a computing device according to an embodiment of the invention.

Detailed Description

The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by showing examples of the invention.

In the embodiment of the invention, the coherent receiving technology mixes the received signal light with the intrinsic light generated by the intrinsic laser through a mixer to obtain an intermediate frequency signal which changes with the frequency, the phase and the amplitude of the signal light according to the same rule, the intermediate frequency signal is converted by a photoelectric detector and then outputs an electric signal, and the output electric signal is demodulated to obtain the data information loaded on the signal light. For intensity-modulated signal light, the coherent received optical signal is a mixed signal of the signal light and the intrinsic light with larger optical power, so that the optical signal power is enhanced, and the requirement of high receiving sensitivity in an optical network system can be met.

In PON networks, the operating wavelengths of different ONUs in the upstream direction are not exactly the same, and wavelength drift occurs at different times in the operating wavelength of the same ONU due to the influence of the operating conditions of the laser transmitters in the ONUs. Due to the above-mentioned phenomenon of uncertainty of wavelength, coherent reception in the uplink direction may generate a problem that the optical wavelength difference between the intrinsic light and the uplink signal exceeds the coherent mixing range, and signal detection fails.

The embodiment of the invention provides a coherent receiving method, a signal processing method and a system, which are used for solving the problem that signal detection fails due to the fact that the optical wavelength difference between intrinsic light and uplink signals exceeds a coherent mixing range. For a better understanding of the present invention, a coherent reception method, a signal processing method and a system according to embodiments of the present invention will be described in detail below with reference to the accompanying drawings, and it should be noted that these embodiments are not intended to limit the scope of the present disclosure.

Fig. 1 is a schematic diagram of a topology of a passive optical network according to an embodiment of the present invention. As shown in fig. 1, the PON system may include an OLT at the office side, and one or more ONUs such as ONU1, ONU2, … … ONUn at the user side, where n is an integer greater than or equal to 1. Between the OLT and the ONUs, an optical distribution network (ODN, optical Distributed Network) may include passive devices such as optical fibers and splitters. Wherein the ODN is configured to provide an optical transmission medium for a physical connection between the OLT and the ONU. PON systems employ a point-to-multipoint network topology. As an example, the OLT, which is a central node of the passive optical network, may be located at a communication facility (e.g., a central office) of the access provider, and the ONUs, which are user nodes, may be located at or near the access user's premises.

Fig. 2 shows a flowchart of a coherent reception method according to an embodiment of the present invention. In one embodiment, a coherent reception method may be used for the OLT, the coherent reception method including the following steps S110 to S120.

Step S110, a downlink message is sent to the optical network unit ONU, and the downlink message is used for triggering the ONU to adjust signal transmission parameters. And step S120, in response to receiving the adjusted optical signal, performing coherent mixing processing on the optical signal and an intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal with a frequency value within an intermediate frequency allowable value range.

According to the coherent receiving method of the embodiment of the invention, the OLT can trigger the ONU to adjust the emission parameters of the uplink signal light through the downlink message, so that the intermediate frequency signal frequency value corresponding to the adjusted emission light signal (namely, the difference value between the frequency value of the ONU emission light signal received by the OLT and the frequency value of the OLT intrinsic light signal) is within the intermediate frequency allowable value range, thereby meeting the performance requirement of the coherent receiver and solving the problems that the working wavelength in the uplink direction in the passive optical network system is uncertain and exceeds the intermediate frequency receiving range of the coherent receiver in the OLT.

In the following description of the embodiments of the present invention, performance requirements of a coherent receiver are satisfied, including, but not limited to, that the coherent receiver satisfies receiver sensitivity requirements, for example, a power value of a received optical signal is greater than or equal to a preset power threshold under a certain error condition, and after signal demodulation, clock recovery, data analysis, CRC check is correct, and message analysis is correct for the received optical signal.

The intrinsic light source adopted by the OLT in the embodiment of the invention can not drift along with the working temperature and the working time under the action of the laser chip temperature control device or the wavelength locking device. That is, the OLT employs an intrinsic light source that is wavelength stable. In the PON system, guard Time between upstream burst packets sent by different ONUs is very short, if an adjustable laser is adopted as an intrinsic light source in the OLT, when signal wavelengths of different ONUs are received, the upstream signal is tuned by tuning the adjustable laser wavelength, so that tuning Time of the adjustable laser wavelength is required to be very fast, and it is generally difficult for the adjustable laser to meet the requirement, and the fast adjustable laser has high cost. Compared with the prior art, the OLT in the embodiment of the invention has the advantages of lower cost and easier realization due to the adoption of the intrinsic light source with stable wavelength.

In one embodiment, the intermediate frequency allowable value range is a frequency value range of an intermediate frequency signal that can meet performance requirements of the coherent receiver, which is determined in advance according to a type of the coherent receiver of the OLT. In the description of the embodiments described below, the range of frequency values of the intermediate frequency signal determined according to the type of the coherent receiver may be referred to as an intermediate frequency allowable value range of the coherent receiver of the OLT, and the frequency values of the intermediate frequency signal within the intermediate frequency allowable value range may be referred to as an intermediate frequency allowable value.

In this embodiment, the intermediate frequency signal light meeting the performance requirement of the coherent receiver can be received and correctly resolved by the OLT. In one embodiment, the OLT may monitor that the ONU is in a registration activation phase; or ONU is in normal working phase; or monitoring that the ONU is in a normal working stage and wavelength drift occurs, and sending a downlink message to the ONU so as to trigger the ONU to adjust signal transmission parameters.

The registration flow of the ONU in the registration activation phase is briefly described below. When the ONU is just electrified and is not registered, the ONU is in an initial stage state, namely an O1 state, and when the ONU in the O1 state receives a downlink flow, the ONU is transferred to a standby state, namely an O2 state; the ONU in the O2 state carries out relevant configuration according to network parameters carried in the downstream, wherein the relevant configuration comprises but is not limited to delimiters, power modes, preset equalization time delay and the like, and is transferred to a serial number state, namely an O3 state; the OLT sends a Serial-Number discovery sequence message to the ONU in the O3 state, and the Serial-Number discovery sequence message is used for discovering a new ONU and the Serial Number of the new ONU; when the OLT discovers a new ONU, a logic number ONU-ID is allocated to the new ONU, and the ONU transfers to a ranging state, namely an O4 state after passing through the received ONU-ID; when different ONU transmitting signals reach the OLT, the ONU needs an equalization Time delay, the equalization Time delay can be measured by the OLT for measuring the distance between the ONU and the OLT, and after the ONU receives the equalization Time delay ranging_Time message from the OLT, the ONU executes the equalization Time delay value which needs to be inserted and then shifts to an operation state, namely an O5 state. At this time, the ONU completes the registration process, and may send uplink data and physical layer operation management and maintenance (PHYSICAL LAYER Operations, administation AND MAINTENANCE, PLOAM) messages under the control of the OLT.

According to the coherent receiving method provided by the embodiment of the invention, the ONU can be triggered to adjust the signal transmitting parameters in the ONU registration activation stage, and the signal transmitting parameters of the ONU can be adjusted on line according to the monitored ONU wavelength drift when the PON system normally works, so that the working wavelength of the ONU in the upstream direction in the PON system meets the requirement of the intermediate frequency receiving range of the OLT coherent receiver, and the normal communication between the OLT and the ONU is ensured.

In one embodiment, the ONU adjusts signal transmission parameters including, but not limited to, adjusting the wavelength of the optical signal and adjusting the frequency of the optical signal. When the signal transmitting parameters are adjusted, the signal transmitting parameters can be directly adjusted, and the purposes of adjusting the wavelength of the transmitted optical signals or adjusting the frequency of the transmitted optical signals can be achieved by adjusting the working parameters of the transmitters in the ONU.

Illustratively, the transmitter operating parameters in the ONU include, but are not limited to, transmitter operating temperature, thermoelectric cooler (Thermo Electric Cooler, TEC) current, wavelength tuning current, and the like.

In one embodiment, the step of sending the downlink message in step S110 may specifically include the following steps S111-S112.

S111, determining the optical parameter information of the uplink signal according to at least one of the intermediate frequency allowable value range and the frequency value of the intrinsic optical signal. S112, sending a downlink message carrying uplink signal light parameter information.

In this embodiment, the intermediate frequency allowable value range is a frequency value range of an intermediate frequency signal that can meet the performance requirement of the coherent receiver, which is determined in advance according to the type of the coherent receiver of the OLT.

As one example, where the coherent receiver type is homodyne coherent, the intermediate frequency value of the homodyne coherent receiver may be 0 or much smaller than the signal sampling frequency, e.g., smaller than the signal sampling frequency and a difference from the signal sampling frequency is greater than a frequency difference threshold; when the coherent receiver type is heterodyne coherence, the intermediate frequency value of the heterodyne coherent receiver can be greater than the signal baud rate and less than the receiver bandwidth, or greater than the signal-originating transmitter bandwidth and less than the receiver bandwidth. The intermediate frequency value of the coherent receiver, i.e. the intermediate frequency allowable value of the coherent receiver, is determined according to the type of the coherent receiver.

In the above step S112, the downlink message may be a PLOAM message. When the downlink message carries the uplink signal light parameter information, the method can be realized by modifying the format of the existing downlink PLOAM message or adding the downlink broadcast PLOAM message.

Further, the downlink message includes, but is not limited to, a broadcast PLOAM message, and may also be a unicast PLOAM message or other parameter adjustment instruction or parameter adjustment message sent to the ONU.

As an example, the newly added downstream broadcast PLOAM message may include: uplink physical layer overhead (PHYSICAL LAYER Overhead upstream, PLou), assignment logical number message assignment_ONU-ID MESSAGE, registration Request message Request Registration message, calibration Request message, or Coherent optical working channel, etc.

Table 1 below shows the message format definition of a downstream broadcast PLOAM message, taking the example of a coherent_working_channel message.

It should be noted that, by the message format definition described in table 1 above, the message format definition may be used not only to define the message format of the newly added downstream PLOAM message, but also to modify the message format of other types of downstream PLOAM broadcast messages sent by the OLT in the ONU registration activation stage.

As can be seen from the above description, in one embodiment, the step S111 may specifically include: taking the frequency channel value or the wavelength channel value of the intrinsic optical signal as uplink signal optical parameter information; or taking a target emission parameter value corresponding to the frequency value of any intermediate frequency signal in the intermediate frequency allowable value range as uplink signal light parameter information; or the emission parameter adjustment direction and the emission parameter adjustment value obtained by calculation according to the frequency value of the intrinsic optical signal and the frequency value of the intermediate frequency signal are used as the uplink signal optical parameter information.

In the following description of the embodiments, the target transmission parameter value may be within an intermediate frequency allowable value range, or an optimal value may be preset in the OLT according to the coherent reception performance of the coherent receiver in the OLT. The target transmission parameter value may be, for example, any one of a frequency value of an optical signal transmitted by the ONU, a wavelength value of the optical signal, or a transmitter operation parameter of the ONU; the emission parameter adjustment value may be a frequency adjustment value of the optical signal or a wavelength adjustment value of the optical signal. The OLT may select to transmit the upstream signal optical parameter information in a frequency value or a wavelength value according to the scaling type of the ONU.

As an example, when the uplink signal optical parameter information carried in the downlink message is a wavelength channel value of the intrinsic optical signal, the ONU may set the wavelength of the transmitted optical signal according to a locally stored correspondence table between the intrinsic optical source wavelength channel value and the transmission wavelength.

As an example, when the optical parameter information of the uplink signal carried in the downlink message is the frequency value of the intrinsic optical signal and the frequency value of the intermediate frequency signal within the intermediate frequency allowable range, the ONU may calculate the frequency value of the optical signal transmitted by the ONU according to the two values, specifically, the difference between the frequency value of the optical signal transmitted by the ONU and the frequency value of the intrinsic optical signal is within the intermediate frequency allowable range.

In the embodiment of the invention, the wavelength value unit or the frequency value unit can be adjusted according to the intrinsic optical signal and the calibration lattice point and the calibration precision of the transmitter in the ONU.

According to the coherent receiving method provided by the embodiment of the invention, the OLT sends the downlink message to the ONU, and the ONU can directly adjust the signal transmitting parameter to meet the performance requirement of the coherent receiver according to the uplink signal light parameter information carried in the downlink message, so that the optical signal transmitted by the ONU can be calibrated efficiently and accurately.

In one embodiment, the step S111 may specifically include: and determining an adjustable range of the transmission parameters according to the frequency value of the intrinsic optical signal and the bandwidth of the coherent receiver of the OLT, and taking the adjustable range of the transmission parameters as the optical parameter information of the uplink signal.

In this embodiment, the OLT sends a downstream message to the ONU, and the ONU may adjust, according to the upstream signal optical parameter information carried in the downstream message, the signal transmission parameter to a corresponding intermediate frequency signal frequency value within a frequency range of the OLT coherent receiver bandwidth.

Further, when the signal transmission parameter adjusts the corresponding intermediate frequency signal frequency value to be within the frequency range of the bandwidth of the OLT coherent receiver and within the intermediate frequency allowable value range, the OLT can correctly analyze the uplink message transmitted by the optical signal and transmit the uplink message to the ONU.

In one embodiment, after the ONU sends the upstream message to the OLT, if the feedback message corresponding to the upstream message is not received, the transmission parameter of the optical signal may be adjusted within a frequency value range within the receiver bandwidth of the OLT.

Taking the transmission parameter as a wavelength value as an example, a schematic diagram of the ONU adjusting the transmission parameter of the optical signal within the OLT coherent receiver bandwidth is described by using fig. 3a and 3 b.

Fig. 3a shows a schematic diagram of an ONU adjusting the wavelength of an optical signal in one embodiment, and fig. 3b shows a schematic diagram of an ONU adjusting the wavelength of an optical signal in another embodiment. In fig. 3a and 3b, λ _{s_c} represents the wavelength value of the current optical signal, dλ _s represents the wavelength adjustment interval value, that is, the wavelength adjustment step, λ _{s_x} represents the wavelength value of the adjusted optical signal, and λ _{LO_} represents the wavelength value of the intrinsic optical signal employed by the OLT. Δf _IF represents an intermediate frequency allowable value range of the coherent receiver, and Δf _IF/c represents a wavelength range corresponding to the intermediate frequency allowable value range.

As shown in fig. 3a, due to the symmetry of the positive and negative intermediate frequencies in the coherent receiver, the wavelength range corresponding to the intermediate frequency allowed range may be distributed on both sides of the wavelength value λ _{LO_c}.

In one embodiment, the wavelength adjustment upper limit value lambda _max is calculated according to the wavelength value lambda _{LO_c} of the intrinsic optical signal and the frequency range of the bandwidth of the coherent receiver of the OLT; and calculating a wavelength adjustment lower limit value lambda _min according to the wavelength value lambda _{LO_c} of the intrinsic optical signal and the frequency range of the bandwidth of the OLT coherent receiver.

In fig. 3a, when the coherent receiver is a heterodyne coherent detection receiver, the intermediate frequency allowable range may be located in a long wavelength direction or a short wavelength direction of a wavelength value λ _{LO_c} of the intrinsic optical signal. The long wavelength direction is the wavelength direction greater than the wavelength value lambda _{LO_c}, and the short wavelength direction is the wavelength direction less than the wavelength value lambda _{LO_c}.

Specifically, the wavelength value λ _{s_c} of the current optical signal is adjustable to a wavelength adjustment upper limit value λ _max in the long wavelength direction, the wavelength adjustment upper limit value λ _max is greater than the wavelength value λ _{LO_c} of the intrinsic optical signal, and the wavelength value λ _{s_c} of the current optical signal is adjustable to a wavelength adjustment lower limit value λ _min in the short wavelength direction, wherein a difference between the wavelength adjustment upper limit value λ _max and the wavelength adjustment lower limit value λ _min may be less than twice the OLT coherent receiver bandwidth.

In this embodiment, the ONU may adjust the wavelength value of the optical signal in a frequency range of less than twice the OLT coherent receiver bandwidth, where the central value of the frequency range of less than twice the OLT coherent receiver bandwidth may be the wavelength value λ _{LO_c} of the intrinsic optical signal.

Specifically, the ONU may first select the long wavelength direction to adjust the wavelength of the uplink signal, and if the adjustment value wavelength adjustment upper limit value λ _max does not fall within the intermediate frequency allowable value range, the ONU may adjust the wavelength of the uplink signal in the short wavelength direction until the adjusted wavelength λ _{s_x} of the uplink signal falls within the intermediate frequency allowable value range.

Similarly, the ONU may first select the short wavelength direction to adjust the wavelength of the uplink signal, and if the adjustment value wavelength adjustment upper limit value λ _min does not fall within the intermediate frequency allowable value range, then adjust the wavelength of the uplink signal in the long wavelength direction until the adjusted wavelength λ _{s_x} of the uplink signal falls within the intermediate frequency allowable value range.

As shown in fig. 3b, when the OLT uses the homodyne coherent detection receiver, the difference between the wavelength value λ _{s_c} of the current optical signal and the wavelength value λ _{LO_c} of the intrinsic optical signal is located in the frequency range of the OLT coherent receiver bandwidth. The adjustment process of the signal emission parameter is the same as or identical to the adjustment process of the signal light wavelength in fig. 3a, and will not be described here again.

In fig. 3a and 3b, the wavelength adjustment interval dλ _s in the ONU needs to satisfy the condition of dλ _s＜ΔfI_IF/c, that is, the value range of the wavelength adjustment step value should be smaller than the wavelength range corresponding to the intermediate frequency allowable value range of the coherent receiver.

In the embodiment described above in connection with fig. 3a and fig. 3b, the ONU may adjust the signal transmission parameter within the transmission parameter adjustable range according to the received downlink message of the OLT, so that the adjustment manner is more flexible, and the calculation amount of the OLT may be reduced to a certain extent.

In the embodiment of the invention, the parameter value of the intrinsic optical signal in the OLT and the parameter value of the optical signal transmitted by the ONU need to be calibrated and the calibration lattice point is less in requirement. For example, the transmission parameter adjustment value in the ONU, for example, the wavelength adjustment value is smaller than 2 times of the wavelength range corresponding to the bandwidth of the OLT coherent receiver, and the adjusted optical signal meets the requirement of receiving performance of the coherent receiver, for example, the error between the frequency value of the intermediate frequency signal corresponding to the optical signal and the intermediate frequency allowable value is smaller than a preset error threshold. That is, the calibration lattice point of the transmitter in the ONU can satisfy the condition of less than 2 times of the bandwidth of the OLT coherent receiver, and the calibration accuracy satisfies the condition of the receiving performance requirement of the coherent receiver.

In the embodiment of the invention, for the ONU with a wider uplink wavelength range, the OLT intrinsic light source and the ONU optical module need to scale a large number of wavelength channels. For example, a 50GHz bandwidth coherent receiver, a 2 times OLT coherent receiver bandwidth corresponds to an O-band wavelength range of approximately 0.7nm.

To further reduce the calibration requirements, the downstream message of the OLT may not carry upstream signal parameter information. After the ONU is connected with the line and receives the downlink message, the transmitted optical parameter value can be blindly adjusted, and the OLT determines whether the frequency difference value of the uplink optical signal adjusted by the ONU and the OLT intrinsic optical signal is within the range of the intermediate frequency allowable value or not by receiving and correctly analyzing the uplink message sent by the ONU. If the OLT receives and correctly parses the upstream message sent from the ONU, the intermediate frequency signal frequency value is within the intermediate frequency allowable value range.

In one embodiment, the coherent reception method may further include: s131, responding to the received uplink message from the ONU, and if the uplink message is analyzed correctly, sending a feedback message aiming at the uplink message, wherein the feedback message is used for indicating that the uplink message is analyzed correctly; s132, if the uplink message carries the adjustment information of the ONU adjustment signal transmission parameters, the feedback message carries the adjustment information.

In one step, the uplink message may or may not carry adjustment information of the signal transmission parameter. When the adjustment information of the signal transmission parameters is not carried, the interval duration of each adjustment of the signal transmission parameters in the ONU is longer than the message round trip duration between the OLT and the ONU, so that the ONU can receive the notification message corresponding to the correct analysis of the uplink message before the next adjustment of the wavelength of the uplink optical signal, and the parameter value of the adjusted uplink optical signal or the working parameter value of the adjusted transmitter can be determined according to the correctly analyzed uplink message.

In one embodiment, if the uplink message carries adjustment information of the ONU adjustment signal transmission parameters, the feedback message may carry the adjustment information.

Wherein the adjustment information may include at least one of the following information items: a transmission parameter setting value and a transmission parameter adjustment frequency sequence number. The transmission parameter setting value may include any one of the following information items: the adjusted optical signal wavelength value, the adjusted optical signal frequency value, and the adjusted transmitter operating parameter.

In the embodiment of the invention, the ONU adjusts the signal transmitting parameter, records the adjusting information in the uplink message, records the adjusting information after the OLT receives and correctly analyzes the uplink message, and notifies the ONU of the adjusting information.

Further, after the ONU is powered down and restarted, the OLT may send a downlink message carrying the adjustment information, so that the ONU adjusts the signal transmission parameter according to the adjustment information, and reduces the wavelength adjustment time in the registration activation stage of the ONU.

In one embodiment, if the number of uplink messages that the OLT is correctly parsed in the specified time period is greater than 1, the coherent receiving method further includes: selecting any one of the correctly resolved uplink messages as the correctly resolved uplink message; or selecting one correctly resolved uplink message with the lowest error rate as the correctly resolved uplink message; or selecting the uplink message with the closest frequency value of the intermediate frequency signal obtained by the corresponding optical signal and the optimal intermediate frequency value as the correctly analyzed uplink message, wherein the optimal intermediate frequency value is the intermediate frequency value of the frequency values in the intermediate frequency allowable value range.

As one example, the OLT sends downstream messages and monitors upstream messages of ONUs. And if only one uplink message is received and the uplink message is correctly analyzed within the appointed duration, the adjustment information carried by the uplink message is sent to the ONU through the feedback message of the uplink message.

As an example, assuming that the optimal intermediate frequency value is in the middle of the intermediate frequency allowable value range, when the OLT monitors a plurality of uplink messages and correctly analyzes the uplink messages reported by a plurality of ONUs within a specified duration, the OLT may select to send adjustment information carried by the most middle uplink message, and send the feedback message of the selected uplink message to the ONUs.

As an example, when the OLT monitors and correctly analyzes two uplink messages within a specified duration, the OLT sends the adjustment information carried in any one of the two uplink new messages to the ONU through a feedback message of the selected uplink message.

In the embodiment of the present invention, if the uplink message carries the adjustment information of the signal transmission parameter, the interval duration of each adjustment of the signal transmission parameter may be smaller than the message round trip time between the ONU and the OLT.

In one embodiment, after the OLT sends a feedback message for the upstream message to the ONU, the ONU may set the signal transmission parameters of the ONU in the normal working stage according to the adjustment information of the signal transmission parameters carried in the feedback message. And the working parameters of the transmitter in the ONU normal working phase can be determined according to the signal transmission parameters in the normal working phase.

In the embodiment of the invention, when the uplink signal parameter information is not carried in the downlink message sent by the OLT, the ONU adjusts the signal transmission parameter in a preset uplink wavelength range when triggering and adjusting the signal transmission parameter, and transmits the uplink message carrying the adjustment information of the signal transmission parameter to the OLT by utilizing the adjusted optical signal. And the OLT judges whether the adjusted optical signal meets the performance requirement of the coherent receiver according to whether the received uplink message can be correctly analyzed. If the performance requirement of the coherent receiver is met, the ONU is informed of setting the signal transmission parameters and the working parameters of the transmitter in the normal working stage according to the adjustment information of the signal transmission parameters, and the optical signals transmitted by the ONU in the normal working stage are received in a coherent mode. In the method, the OLT does not need to adopt an adjustable laser as an intrinsic light source, so that the calibration requirement and the quick response requirement of the OLT end on the transmitted light signals are reduced, and compared with the method using a quick adjustable laser, the method can effectively save the cost.

The coherent receiving method of the embodiment of the invention can also utilize the photoelectric detector in the coherent receiver to output the alternating current power value after photoelectric detection of the intermediate frequency signal, and determine the corresponding relation of the output alternating current power value along with the change of the frequency value of the intermediate frequency signal, thereby utilizing the intermediate frequency allowable value and the corresponding relation to determine the alternating current power value point corresponding to the intermediate frequency allowable value; the OLT may send the ac power value point to the ONU, so that the ONU adjusts the transmitter operating parameter according to the ac power value point.

The basic principle that the ac power value outputted after detection varies with the intermediate frequency signal is briefly described below. The mixer in the coherent receiver can perform mixing processing on the received optical signal and the local oscillation signal adopted by the OLT to obtain an intermediate frequency signal, and the photoelectric detector outputs a photocurrent signal after detecting the intermediate frequency signal.

As an example, the mixer may be a 180 degree optical mixer, i.e. a 2 x 2 coupler with two port input, two port output, and 180 degree phase difference of the output optical signals. In practical application, the type of the mixer is not particularly limited.

In one embodiment, the optical field distribution of the intrinsic optical signal and the optical field distribution of the signal light emitted by the ONU can be expressed as the following expression (1) and expression (2), respectively.

In the above expressions (1) and (2),Representing the light field distribution of the intrinsic optical signal, ω _LO representing the frequency of the intrinsic optical signal,/>Representing the phase of the intrinsic optical signal, a _LO representing the power of the intrinsic optical signal; /(I)Represents the optical field distribution of the uplink signal light, ω _s represents the frequency of the uplink optical signal,/>The phase of the uplink optical signal is represented, and a _s represents the power value of the uplink optical signal.

In one embodiment, the ac power value of the photocurrent signal output after detection by the photodetector is monitored may be expressed as the following expression (3).

In the above expression (3), I (t) represents a photoelectric value that varies with the detection time, a _LO represents the power of the intrinsic optical signal, and a _s represents the power of the optical signal. Δωt represents the frequency of the intermediate frequency signal that varies with time, Δω represents the frequency of the intermediate frequency signal, i.e. the frequency offset between the frequency ω _s of the optical signal and the frequency ω _LO of the intrinsic optical signal,Representing the phase of the intermediate frequency signal, i.e. the phase of the optical signal/>Phase/>, with intrinsic optical signalPhase offset between them.

Since the power value A _LO of the intrinsic optical signal is a constant value of direct current which is changed from continuous light to time, and can be filtered by the DC blocking circuit, and the power A _s of the uplink signal light is weak and negligible, the above expression (3) can be simplified as

In one embodiment, using the coherent receiver bandwidth frequency response curve H (ω), the coherent receiver received power versus frequency response function, i.e., two photocurrents obtained under different intermediate frequency signal frequency values, may be represented by the following expressions (4) and (5), respectively.

In the above expressions (4) and (5), H' (Δω) and H (ω) satisfy the conditionH' (ω) represents the receiver current frequency response curve determined by the coherent receiver bandwidth, i.e., the response curve of the receiver output current magnitude as a function of the magnitude of the input optical signal frequency value, and is proportional to the coherent receiver bandwidth (power) to the power of 1/2 of the frequency response curve H (ω). In this embodiment, the frequency value of the optical signal input to the receiver after passing through the mixer is the frequency value Δω of the intermediate frequency signal.

As an example, the photocurrent represented by the above expression (4) may be used as the monitor current, i.e., I (t) =i _r1 (t) is set, and the power after ac power detection may be represented by the following expression (6):

In the above expression (6), R represents the equivalent load resistance of the photodetector, P _AC+DC represents the total power value detected by the photodetector, P _AC represents the alternating current power component in the total power value detected, P _DC represents the direct current power component in the total power value, and the same symbols in the expression (6) as those in the above expressions (1) to (5) represent the same meanings, and are not repeated here.

Further, the ac power monitoring may be performed after the balance detection in the above expression (6)And/>The photocurrent at this time can be expressed as the following expression (7) by the balance detection cancellation.

In the same way, can obtainWherein, the same symbols in expression (7) as those in expressions (1) to (5) above denote the same meanings, and are not described in detail herein.

As can be seen from the description of the foregoing embodiments, when the ONU adjusts the signal transmission parameter in the upstream wavelength range, for example, tunes the wavelength, the intermediate frequency value of the intermediate frequency signal detected in the OLT changes correspondingly according to the tuned wavelength, and it can be obtained that the change curve of the ac power value P _AC after ac power detection is consistent with the bandwidth frequency response curve of the coherent receiver. That is, the coherent receiver photodetector has a filter characteristic for the received coherent intermediate frequency optical signal due to its own frequency response range. Therefore, the frequency value of the received intermediate frequency signal of the coherent receiver can be obtained by monitoring the change of the alternating current power value P _AC detected by the photoelectric detector in the coherent receiver. Further, the OLT may send a parameter adjustment instruction carrying an operating parameter to the ONU by determining whether the frequency value of the intermediate frequency signal obtained by monitoring the change of the ac power value is within the range of the intermediate frequency allowable value, so that the intermediate frequency signal received by the OLT after the ONU adjusts the signal transmission parameter can meet the performance requirement of the coherent receiver.

As an example, for a photodetector with a 3-dB bandwidth of OLT coherent receiver bandwidth (bw_pd), when the ac power value P _AC is half of the maximum ac power value, the frequency value of the corresponding intermediate frequency signal is ±bw_pd, and when the ac power value P _AC is the maximum ac power value, the frequency value of the corresponding intermediate frequency signal is around frequency 0.

Based on the description of the above embodiment, after step S110, the coherent reception method may further include the following steps S140 to S143.

And S140, monitoring the alternating current power value of the photocurrent signal output after the photoelectric detection of the intermediate frequency signal by the coherent receiver in the OLT, and monitoring the alternating current power value change detected by the photoelectric detector in the coherent receiver to obtain the frequency value of the intermediate frequency signal received by the coherent receiver. S141, determining a first corresponding relation between the alternating current power value and the intermediate frequency value according to the alternating current power value and the frequency value of the intermediate frequency signal. S142, according to the first corresponding relation and the frequency value in the intermediate frequency allowable value range, calculating an alternating current power value point corresponding to the frequency value in the intermediate frequency allowable value range. S143, working parameters corresponding to the alternating current power value points are determined, and parameter adjusting instructions carrying the working parameters are sent to the ONU, so that the ONU adjusts the working parameters of the transmitter according to the carried working parameters; the intermediate frequency allowable value range is a frequency value range of an intermediate frequency signal which is determined in advance according to the type of the coherent receiver of the OLT and can meet the performance requirement of the coherent receiver.

In step S141, the first correspondence relationship may be represented as a curve of ac power value with intermediate frequency value. In step S142, the intermediate frequency allowable value determined based on the type of the coherent receiver may specifically include: and obtaining an empirical value of the intermediate frequency allowable value meeting the performance requirement of the coherent receiver according to information such as a modulation format, a modulation rate, a coherent receiver type, a photoelectric detector bandwidth and the like of an optical signal in the optical network system in advance, and taking the empirical value as the intermediate frequency allowable value of the coherent receiver.

As an example, when the coherent receiver type is homodyne coherence, the frequency value of the intermediate frequency grant is 0 or close to 0, e.g. the frequency value is less than or equal to the first frequency threshold.

As another example, when the coherent receiver type is heterodyne coherent, the value of the intermediate frequency allowed value is within or close to the frequency value range of the OLT coherent receiver bandwidth, e.g. the frequency difference from the frequency upper limit value of the OLT coherent receiver bandwidth is smaller than the second frequency threshold or the frequency difference from the frequency lower limit value of the OLT coherent receiver bandwidth is smaller than the third frequency threshold.

In one embodiment, a table of correspondence between receiver types and empirical values of intermediate frequency allowable values may be stored in the OLT, which reads the intermediate frequency allowable values corresponding to the receiver types by table lookup.

In step S143, the OLT determines the working parameter corresponding to the ac power value point, which may be implemented by simultaneously monitoring, with the ONU, an upstream message carrying the working parameter (for example, a time value) sent by the ONU.

For ease of understanding, how to determine the correspondence between the ac power value and the time value is described below with reference to fig. 4. Fig. 4 is a schematic diagram showing a time-dependent change curve of an ac power value in an embodiment of the present invention. In fig. 4, the X-axis represents time, and the Y-axis represents the ac power value output after detection by the photodetector.

In the embodiment of the invention, after the ONU receives the downlink message in the registration activation stage, the ONU tunes the wavelength of the optical signal in a preset uplink wavelength range. Specifically, wavelength tuning may be performed first in a first tuning direction, and when tuning to a wavelength end point value of the first tuning direction, wavelength tuning may be performed in a second tuning direction, i.e., in a direction opposite to the first tuning direction.

The first tuning direction is the wavelength endpoint value which is the lower limit value of the uplink wavelength range when the first tuning direction is adjusted from the upper limit value of the uplink wavelength range to the lower limit value of the uplink wavelength range; when the first tuning direction is adjusted from the lower limit value of the upstream wavelength range to the upper limit value of the upstream wavelength range, the wavelength endpoint value is the upper limit value of the upstream wavelength range.

Taking the first tuning direction as an example of adjusting the wavelength lower limit value of the uplink wavelength range from the upper limit value of the uplink wavelength range, in one embodiment, after receiving the downlink stream in the registration activation stage, the ONU performs wavelength tuning in the first adjusting direction in the uplink wavelength range according to a first time interval Δt1, records a wavelength tuning time point nΔt1 corresponding to each wavelength tuning, and continues to perform wavelength tuning in the second adjusting direction according to a specified time interval Δt1 when the wavelength lower limit value in the uplink wavelength range is reached.

After the OLT sends the downstream message of registration, the detected alternating current power value is monitored and recorded according to a second time interval delta T2, and after the alternating current power value is detected, the power detection time point m delta T2 corresponding to each power monitoring is recorded, so that a change curve of the alternating current power value along with the m delta T2 is obtained.

As shown in fig. 4, for simplicity of description, the frequency value of the intermediate frequency signal obtained by mixing the optical signal emitted after the OLT detects the ONU and performs wavelength tuning with the intrinsic optical signal may be simply referred to as an intermediate frequency tuning value, where Δt1=Δt2=Δt. And assuming that the time required for the ONU to adjust from the wavelength upper limit value to the wavelength lower limit value in the upstream wavelength range in the first adjustment direction is T, and assuming that the time required for the OLT to detect the maximum intermediate frequency value to the minimum intermediate frequency value of the intermediate frequency tuning value corresponding to the ac power value is T'.

Due to the symmetry of the positive and negative intermediate frequencies, m _r Δt2 and n _r Δt1 can take corresponding sets of values. As shown in fig. 4, corresponding to an optical signal emitted by an ONU after performing wavelength tuning at a wavelength tuning time point n _r1 Δt1, a time point when the OLT detects an ac power value is m _r1 Δt2; corresponding to an optical signal emitted by the ONU after performing wavelength tuning at a wavelength tuning time point n _r2 Δt1, a time point when the OLT detects an ac power value is m _r2 Δt2.

In one embodiment, the correspondence relationship between the wavelength tuning time point n _r Δt1 and the power detection time point m _r Δt2, which are determined from the wavelength tuning time point nΔt1 and the power detection time point mΔt2, can be expressed as the following expression (8):

n_rΔT1-T＝m_rΔT2-(T′+(m₀ΔT2-T′)/2) (8)

In expression (8), m ₀ Δt2 may be a time value corresponding to when the OLT detects the ac power, in which the ONU continues to perform wavelength tuning in the second adjustment direction at a specified time interval from the lower limit value of the wavelength to the upper limit value of the wavelength.

In the above embodiment, the OLT may obtain the intermediate frequency allowable value according to the type of the coherent receiver, and obtain the corresponding ac power value point according to the intermediate frequency allowable value and the correspondence between the ac power value and the frequency value of the intermediate frequency signal; according to the second corresponding relation between the alternating current power value and the time and the corresponding alternating current power value, calculating to obtain a corresponding monitoring time point; and (3) determining a corresponding wavelength tuning time point according to the corresponding monitoring time point and the corresponding relation between the wavelength tuning time point and the power detection time point described in the expression (8).

In one embodiment, the step of determining the operation parameter corresponding to the ac power value in step S143 may specifically include steps S1431 to S1435.

In step S1431, an upstream message sent by the ONU after the adjustment of the signal transmission parameter is monitored, where the upstream message carries the parameter adjustment time and the working parameter used in the parameter adjustment time.

In step S1432, a second correspondence relationship between the ac power value and the monitoring time is determined by the monitored ac power value and the corresponding monitoring time.

Step S1433, calculating the monitoring time corresponding to the AC power value point by using the AC power value point corresponding to the frequency value in the intermediate frequency allowable value range and the second corresponding relation to obtain the monitoring time calculated value.

Step S1434, determining the parameter adjusting time corresponding to the monitoring time calculated value, and obtaining the parameter adjusting time calculated value corresponding to the alternating current power value point.

In one embodiment, according to the monitoring time for monitoring the ac power value, an uplink message transmitted by an optical signal corresponding to the monitored ac power value may be obtained, a parameter adjustment time carried in the transmitted uplink message may be obtained, and a correspondence between the monitoring time and the parameter adjustment time may be determined.

In one embodiment, the corresponding relationship between the monitoring time and the parameter adjusting time may be determined by adjusting the signal transmission parameter according to a first time interval of the parameter adjusting time from a first designated time point, and monitoring the ac power value of the output photocurrent signal after the photoelectric detection of the coherent receiver according to a second time interval of the monitoring time from a second designated time point.

The first designated time point is an ac power value of the first photocurrent signal after the OLT sends the downlink message and the coherent receiver is monitored to photoelectrically detect the downlink message.

In an exemplary embodiment, the first specified time point is a parameter adjustment time when the ONU adjusts the signal transmission parameter in the opposite wavelength adjustment direction, and the second specified time point is a monitoring time when the ac power value of the photocurrent signal is monitored after the adjustment in the opposite wavelength adjustment direction.

As a specific example, the correspondence between the monitoring time and the tuning time may be determined using the above expression (8).

In step S1435, the operation parameter used when the parameter adjustment time is the parameter adjustment time calculation value is used as the operation parameter corresponding to the ac power value point.

According to the coherent receiving method provided by the embodiment of the invention, when the OLT monitors wavelength tuning and working parameter information reported by the ONU, the received information needs to be subjected to complete signal demodulation and frame analysis, and the processing time is long. Therefore, based on the monitored alternating current power value of the photoelectric detector in the OLT, namely the photocurrent after the detection of the intermediate frequency signal, the transmission parameters of the optical signals in the ONU are adjusted, and signal demodulation and frame analysis in the OLT are not needed, so that the data processing amount and processing time of the OLT are further reduced.

In one embodiment, the ONU is the first ONU to be on-line in an optical distribution network, the optical distribution network being located between the OLT and the ONU; the method further comprises the steps of: and carrying working parameters of the corresponding alternating current power value points of the intermediate frequency allowable value range in the registration activation downlink message sent to other ONU in the optical distribution network.

When the working parameters corresponding to the alternating current power value points in the intermediate frequency allowable value range are multiple groups, selecting the working parameters corresponding to the intermediate frequency values in the intermediate frequency allowable value range; the method comprises the steps that an OLT monitors an alternating current power value when a first online ONU registration activation stage carries out wavelength tuning in an intermediate frequency allowable value range, an intermediate frequency value corresponding to the monitored alternating current power value is obtained, and in the process of monitoring the wavelength tuning, the obtained intermediate frequency signal frequency value range meeting the performance requirement of a coherent receiver in the OLT is obtained.

In this embodiment, the OLT may determine a correspondence between an ac power value obtained by performing wavelength tuning on the first ONU in the online ONU in the registration activation stage and an intermediate frequency value, and confirm, according to meeting a performance requirement condition of the coherent receiver (for example, the OLT receives and correctly parses an uplink message), an intermediate frequency allowable value and an ac power value point corresponding to the intermediate frequency allowable value, and send a notification message carrying the ac power value point, so that the ONU adjusts to a receiver working parameter corresponding to the ac power value point. In this embodiment, the OLT monitors the ac power value change during the wavelength tuning at the first on-line ONU registration activation stage, and determines whether the receiver performance requirement is met during the ac power value change. Specifically, the first online ONU performs wavelength tuning in a registration activation stage to obtain an alternating current power value change, and an intermediate frequency value is obtained, and meanwhile, the OLT monitors an intermediate frequency value point meeting the performance requirement of the OLT coherent receiver in the ONU tuning process, and an intermediate frequency allowable value range is obtained.

The downlink message sent by the OLT subsequently carries the intermediate frequency allowable value, so that the subsequent ONU obtains the intermediate frequency allowable value. If the uplink signal optical parameter information carried in the downlink message is received by the subsequent OLT as the wavelength value of the intrinsic optical signal or the frequency value of the intrinsic optical signal, the transmission parameter adjustment direction and the transmission parameter adjustment value obtained by calculation can be calculated according to the intermediate frequency allowable value and the uplink signal optical parameter information, so as to adjust the signal transmission parameter in the ONU, thereby reducing the uplink calibration time of the subsequent ONU and improving the transmission parameter calibration efficiency.

In one embodiment, if the OLT detects that the variation curve of the ac power value with the power monitoring time is abnormal due to the online collision of the ONUs, for example, the OLT does not conform to the variation trend of the bandwidth response curve of the coherent receiver, the ONU may use a random time back-off collision mechanism. As an example, the back-off time of an ONU is greater than 2 times T, which means the time required for the ONU to adjust from the upper wavelength limit to the lower wavelength limit in the upstream wavelength range, or from the lower wavelength limit to the upper wavelength limit in the upstream wavelength range.

In one embodiment, the ONU may be configured to adjust the wavelength periodically within a specified message period. The specified message period may be, for example, a quiet window or a transmission period of an assigned logical number message assignment _ ONU-ID MESSAGE from the OLT. If the intermediate frequency signal frequency corresponding to the adjusted optical signal is not within the intermediate frequency allowable value range in the designated message period, the next message period can be waited for, and the signal transmission parameter can be restarted or continuously adjusted.

In one embodiment, the signal adjustment method may further include step S150.

Step S150, in response to detecting that the optical signal has wavelength drift and the drift range is within a preset wavelength drift threshold range, a wavelength fine tuning instruction is sent to the ONU according to the signal quality of the optical signal, so that the ONU performs wavelength tuning according to the wavelength fine tuning instruction.

In this embodiment, when the monitoring ONU experiences wavelength drift, wavelength fine adjustment is performed on the optical signal emitted by the OLT, so as to improve the signal quality of the upstream optical signal.

In one embodiment, the signal adjustment method may further include step S160.

Step S160, judging that the ONU needs to adjust the emission parameters of the optical signals when the ONU is in an unregistered state after being on line; if the uplink messages from a plurality of ONUs are received in the adjacent time period, the ONU which allows registration is selected according to the parameter adjustment times carried in the uplink message of each ONU.

In one embodiment, the ONU with the largest number of parameter adjustments may be used as the ONU that needs to be registered. In this embodiment, the probability that the intermediate frequency signal frequency corresponding to the wavelength value of the optical signal of the ONU with the largest number of wavelength adjustments is within the intermediate frequency allowable value range is large.

In an embodiment of the present invention, the signal adjustment method may further include steps S170 and S171.

Step S170, if the frequency value of the monitored intermediate frequency signal is within the intermediate frequency allowable value range of the coherent receiver of the OLT, and the uplink message carried by the signal light corresponding to the intermediate frequency signal meets at least one of the condition that the signal light cannot be analyzed correctly and the error rate is higher than the error rate threshold, determining that the ONU generates uplink data collision. Step S171, notifying the ONU to maintain the operation parameters corresponding to the ac power value points, and performing back-off for the uplink data collision.

In this embodiment, the OLT determines whether an ONU collision occurs according to the monitored ac power value and the result of the analysis of the uplink message frame, and if it determines that an ONU collision occurs, notifies the ONU to hold the corresponding working parameter of the intermediate frequency allowable value and performs the backoff process. As an example, detection mechanisms by the OLT to detect ONU collisions include, but are not limited to: the ac power value is monitored as an intermediate frequency allowable value range but frame analysis or a high error rate cannot be correctly achieved.

In the coherent receiving method described above in connection with fig. 1 to fig. 4, the OLT may trigger the ONU to perform transmission parameter adjustment and online calibration by sending a downlink message, where the intermediate frequency signal frequency corresponding to the adjusted signal light is within the intermediate frequency allowable value range, so as to solve the problem that the working wavelength of the ONU in the uplink direction in the optical network system is uncertain and exceeds the intermediate frequency receiving range of the coherent receiver of the OLT.

Fig. 5 shows a flow chart of a signal processing method according to another embodiment of the invention. As shown in fig. 5, in one embodiment, the signal processing method may be used for an optical network unit ONU, including: s210, adjusting signal emission parameters of the optical signals in response to receiving downlink messages from the Optical Line Terminal (OLT); and S220, transmitting an optical signal to the OLT according to the adjusted signal transmission parameters, so that after the optical signal and the intrinsic optical signal are subjected to coherent mixing processing, an intermediate frequency signal with a frequency value within an intermediate frequency allowable value range is obtained.

According to the signal processing method provided by the embodiment of the invention, the OLT responds to the downlink message received from the optical line terminal OLT, and adjusts the transmitting parameters of the optical signals, so that after the transmitted optical signals and the intrinsic optical signals are coherently mixed in the OLT, the frequency value of the obtained intermediate frequency signal is in the range of the intermediate frequency allowable value, and the influence of the uncertainty of the working wavelength of the ONU in the uplink direction on the communication between the ONU and the OLT in the optical network system is solved.

In one embodiment, the step of adjusting the signal emission parameter of the optical signal in step S210 may specifically include step S211.

Step S211, adjusting signal emission parameters according to uplink signal light parameter information carried in the downlink message, wherein the uplink signal light parameter information is used for indicating the signal emission parameters capable of obtaining intermediate frequency signals with frequency values within an intermediate frequency allowable value range.

In this step, the intermediate frequency allowable value range is a frequency value range of the intermediate frequency signal that can satisfy the performance requirement of the coherent receiver, which is determined in advance according to the type of the coherent receiver of the OLT.

In this embodiment, the ONU may directly adjust the signal transmission parameter to meet the performance requirement of the coherent receiver according to the uplink signal optical parameter information issued by the OLT.

In one embodiment, the step of adjusting the signal emission parameter of the optical signal in step S210 may specifically include steps S212 to S214.

Step S212, the adjustable range of the emission parameter is obtained from the uplink signal light parameter information carried by the downlink message, and the signal emission parameter is adjusted in the adjustable range of the emission parameter. Step S213, the uplink message is sent to the OLT by using the adjusted signal transmission parameters. Step S214, in response to receiving the feedback message of the uplink message, uses the signal transmission parameter corresponding to the uplink message as the signal transmission parameter in the ONU normal working phase.

In step S214, the feedback message is used to instruct the ONU to correctly parse the upstream message sent to the OLT in S213. That is, when the OLT receives an upstream message sent by an ONU using the adjusted signal transmission parameter and correctly analyzes the upstream message, the OLT sends a feedback message of the upstream message to the ONU.

In one embodiment, the interval time of two adjacent adjustments is longer than the message round trip time between the OLT and the ONU, and the frequency value corresponding to the value range of the adjustment step of the signal transmission parameter is smaller than the intermediate frequency allowable value range of the coherent receiver in the OLT.

In this embodiment, the uplink message may or may not carry adjustment information of the signal transmission parameter. If the uplink message in step S213 does not carry the adjustment information of the signal transmission parameter, the interval time between two adjacent adjustments needs to be set to be longer than the message round trip time between the OLT and the ONU, so as to ensure that if the optical signal after the current adjustment meets the performance requirement of the coherent receiver, the notification message corresponding to the correct analysis of the uplink message can be received before the wavelength of the uplink optical signal is adjusted next time.

In this embodiment, the interval time of two adjacent adjustments is longer than the message round trip time between the OLT and the ONU, and the frequency value corresponding to the value range of the adjustment step of the signal transmission parameter is smaller than the intermediate frequency allowable value range of the coherent receiver in the OLT.

In this embodiment, when the signal transmission parameter is adjusted in the transmission parameter adjustable range, if the uplink message carries adjustment information of the signal transmission parameter, the interval duration of two adjacent adjustments may be smaller than the message round trip duration between the OLT and the ONU, so as to improve the parameter adjustment efficiency of the ONU.

In one embodiment, the step of adjusting the signal emission parameter of the optical signal in step S210 may specifically include steps S215-S217.

Step S215, adjusting the signal transmission parameters multiple times within the preset uplink wavelength range. In step S216, the uplink message is transmitted to the OLT by using the signal light after each adjustment, and the uplink message carries the adjustment information of the corresponding signal transmission parameter. Step S217, in response to receiving the feedback message of the uplink message, determining the signal transmission parameters and/or the working parameters of the transmitter in the normal working stage of the ONU according to the adjustment information carried in the uplink message, wherein the feedback message is used for indicating that the uplink message is correctly analyzed.

In this step, the downlink message from the OLT does not include the uplink signal optical parameter information, and the signal transmission parameter can be directly adjusted in the uplink wavelength range, and whether the adjusted optical signal meets the performance requirement of the coherent receiver is determined according to the uplink message fed back after the OLT adjusts the parameter of the ONU.

In one embodiment, the adjustment information of the signal transmission parameter that may be carried in the uplink message may include any one of the following information items corresponding to each adjustment: parameter setting of signal transmitting parameters, tuning frequency serial numbers, transmitting parameter adjusting directions, transmitting parameter adjusting values, parameter adjusting time and working parameters of a transmitter.

In one embodiment, the signal processing method may further include: s230, in response to receiving a registration request sent by the OLT according to the adjusted signal transmission parameters, sending registration information to the OLT; s231, after the OLT is successfully registered, storing the adjusted signal transmission parameters and the working parameters of the transmitters in the ONU; s232, setting the signal transmission parameters in the ONU working state and the transmitter working parameters in the ONU working state according to the stored signal transmission parameters and the stored transmitter working parameters.

In this embodiment, the ONU transmits an optical signal to the OLT according to the adjusted signal transmission parameter, and the OLT receives the adjusted optical signal, and if the adjusted optical signal and the intrinsic optical signal in the OLT are coherently mixed, the OLT obtains that the frequency value of the intermediate frequency signal is within the intermediate frequency allowable value range, and the OLT may start the registration procedure for the ONU. After the ONU completes the registration process, the adjusted wavelength information and the working parameters of the ONU optical module transmitter can be stored, and the ONU optical module transmitter is used for wavelength setting in the normal working stage and transmitter working parameter setting in the normal working stage of the ONU.

In one embodiment, the signal processing method may further include: and in response to receiving the back-off command from the OLT, readjusting the transmission parameters of the optical signal after waiting for a random delay according to the back-off command.

In one embodiment, the signal processing method may further include: and performing wavelength fine adjustment on the optical signal emitted by the OLT in response to receiving the wavelength fine adjustment instruction from the OLT.

In one embodiment, the signal processing method may further include: the adjusting of the signal transmission parameter of the optical signal in step S210 may be to adjust the signal transmission parameter periodically within a specified message period. The specified message period may be, for example, a quiet window. If the adjusted optical signal does not meet the performance requirement of the coherent receiver in the designated message period, the next message period can be waited for, and the signal transmission parameter can be restarted or continuously adjusted.

According to the signal processing method provided by the embodiment of the invention, after the ONU receives the downlink message from the optical line terminal OLT, the transmitting parameter of the optical signal is adjusted until the wavelength of the adjusted optical signal falls into the intermediate frequency receiving range of the coherent receiver, so that the problems of uncertain working wavelength of the ONU in the uplink direction and wavelength drift of the ONU in the optical network system are solved. The ONU adjusts the wavelength information of the uplink signal according to the wavelength information of the uplink signal issued by the OLT, which means that the wavelength of a transmitter in the ONU optical module can be tuned according to the requirement. Specifically, the method can be realized by changing parameters such as the working temperature of the laser chip, the injection current, the cavity size and the like. The correspondence between the parameter and the optical signal wavelength value finally transmitted by the ONU optical module may be stored in the ONU optical module.

Fig. 6 illustrates a schematic structure of an optical line terminal according to an embodiment of the present invention. As shown in fig. 6, in one embodiment, the optical line terminal may include: a signal receiving module 310, a medium access controller 320, and a transmitting module 330.

In one embodiment, the signal receiving module 310 may be implemented as a coherent receiver or a functional module that functions the same or equivalent to a coherent receiver. As shown in fig. 6, in one embodiment, the signal receiving module 310 may include: an intrinsic light source input unit 311, a mixer 312, a photodetector 313, a signal processing module 314, and an ac power monitoring module 315.

Wherein, the intrinsic light source input module 311 is used for inputting the intrinsic light source to the mixer; the mixer 312 is configured to mix the received signal light with the intrinsic light source to obtain an intermediate frequency signal; the photoelectric detector 313 is configured to detect an intermediate frequency signal output by the mixer, and perform photoelectric processing on the intermediate frequency signal to obtain a photocurrent signal; an ac power monitoring module 315 for monitoring an ac power value of the photocurrent signal; the signal processing module 314 can perform signal demodulation, clock recovery, data analysis and the like on the uplink feedback information transmitted by the optical signal; the medium access controller 320 may be configured to provide error detection, CRC check, and frame analysis of the uplink signal, and determine whether the adjusted ONU signal meets the coherent receiving condition; obtaining an alternating current power value change curve according to the alternating current power value provided by the alternating current power monitoring module; storing a coherent allowed frequency value range of the coherent receiver; analyzing an uplink signal sent by the ONU to adjust working parameters; and the downlink signal frames, and sends downlink information to the optical network unit ONU, so as to trigger the ONU to adjust signal transmission parameters, inform the ONU of the information interaction control function between the OLT and the ONU, such as back-off, and the like.

The invention is not limited to the specific modules described above and shown in fig. 6, but in some embodiments the receiving module may comprise only some of the modules therein, i.e. the receiving module in the OLT comprises a more flexible module configuration, as will be described in connection with the specific embodiments below.

Continuing with parameter fig. 6, in one embodiment, an optical line terminal may include a medium access controller module 320 and a signal receiving module 310.

The medium access controller module is used for sending a downlink message to the optical network unit ONU, and the downlink message is used for triggering the ONU to adjust signal transmission parameters.

The signal receiving module 310 is configured to perform coherent mixing processing on the optical signal and the intrinsic optical signal adopted by the OLT in response to receiving the adjusted optical signal, so as to obtain an intermediate frequency signal with a frequency value within an intermediate frequency allowable range.

In this embodiment, the signal transmitting module 330 is configured to convert a downlink message sent by the medium access controller 320 to the optical network unit ONU into an optical signal, and send the optical signal carrying the downlink message.

In one embodiment, medium access controller 320 may include: an uplink parameter determining unit, configured to determine uplink signal optical parameter information according to at least one of an intermediate frequency allowable value range and a frequency value of an intrinsic optical signal; the downlink message sending unit is further used for sending downlink messages carrying uplink signal light parameter information.

In this embodiment, the intermediate frequency allowable value range is a frequency value range of an intermediate frequency signal that can meet the performance requirement of the coherent receiver, which is determined in advance according to the type of the coherent receiver of the OLT. The performance requirements of the coherent receiver are met, including but not limited to that the coherent receiver meets the sensitivity requirements of the receiver, for example, the power value of the received optical signal is greater than or equal to a preset power threshold under a certain error code condition, and after signal demodulation, clock recovery and data analysis are performed on the received optical signal, the CRC is correct, the message is correctly analyzed, and the like.

In one embodiment, the uplink parameter determining unit may specifically be configured to: taking a frequency channel value or a wavelength channel value corresponding to the frequency value of the intrinsic optical signal as uplink signal optical parameter information; or taking a target emission parameter value corresponding to the frequency value of any intermediate frequency signal in the intermediate frequency allowable value range as uplink signal light parameter information; or the emission parameter adjustment direction and the emission parameter adjustment value obtained by calculation according to the frequency value of the intrinsic optical signal and the frequency value of the intermediate frequency signal are used as uplink signal optical parameter information; or determining the adjustable range of the transmission parameter according to the frequency value of the intrinsic optical signal and the bandwidth of the coherent receiver of the OLT, and taking the adjustable range of the transmission parameter as the optical parameter information of the uplink signal.

In one embodiment, the medium access controller 320 in the optical line terminal may further include: a feedback message sending unit, configured to send a feedback message for an uplink message in response to receiving the uplink message from the ONU, where the feedback message is used to indicate that the uplink message is correctly parsed if the uplink message is correctly parsed; and the adjusting information carrying unit is used for carrying the adjusting information in the feedback message if the uplink message carries the adjusting information of the ONU adjusting signal transmitting parameter.

In one embodiment, if the number of uplink messages that are correctly parsed in the specified time period is greater than 1, the feedback message sending unit may be further configured to: for any uplink message which is correctly analyzed, a feedback message is sent; or sending feedback information aiming at the uplink information which is correctly analyzed and has the lowest error rate; or sending a feedback message aiming at an uplink message with the nearest distance between the corresponding intermediate frequency value and the optimal intermediate frequency value, wherein the optimal intermediate frequency value is as follows: intermediate frequency values within the intermediate frequency range of the coherent receiver in the OLT.

In one embodiment, the medium access controller 320 in the optical line terminal may further include: the ac power value monitoring unit is configured to monitor an ac power value output by the ac power monitoring module 315, and monitor a change of the ac power value detected by the photodetector in the coherent receiver to obtain an intermediate frequency signal frequency value received by the coherent receiver; a first relation determining unit, configured to determine a first corresponding relation between the ac power value and the intermediate frequency value according to the ac power value and the frequency value of the intermediate frequency signal; an ac power calculation unit, configured to calculate an ac power value point corresponding to a frequency value in the intermediate frequency allowable value range according to the first correspondence and the frequency value in the intermediate frequency allowable value range; the medium access controller 320 may be further configured to determine an operating parameter corresponding to the ac power value point, and send a parameter adjustment instruction carrying the operating parameter to the ONU, so that the ONU adjusts the operating parameter of the transmitter according to the carried operating parameter; the intermediate frequency allowable value range is a frequency value range of an intermediate frequency signal which is determined in advance according to the type of the coherent receiver of the OLT and can meet the performance requirement of the coherent receiver.

In one embodiment, an optical line terminal may include: the uplink message monitoring unit is used for monitoring uplink messages sent by the ONU after the signal transmission parameters are adjusted, wherein the uplink messages carry parameter adjusting time and working parameters used in the parameter adjusting time; the second relation determining unit is used for determining a second corresponding relation between the alternating current power value and the monitoring time according to the monitored alternating current power value and the corresponding monitoring time; the monitoring time calculation unit is used for calculating the monitoring time corresponding to the alternating current power value point according to the alternating current power value point corresponding to the intermediate frequency allowable value and the second corresponding relation to obtain a monitoring time calculation value; and the working parameter determining unit is used for obtaining the parameter adjusting time point corresponding to the alternating current power value point and working parameters used at the parameter adjusting time point according to the uplink message monitored when the monitoring time is the monitoring time calculated value.

In one embodiment, the ONU is the first ONU to be on-line in an optical distribution network, the optical distribution network being located between the OLT and the ONU; the information carrying module can also be used for carrying the working parameters corresponding to the alternating current power value points in the resending downlink message. When the working parameters corresponding to the alternating current power value points in the intermediate frequency allowable value range are multiple groups, selecting the working parameters corresponding to the intermediate frequency values in the intermediate frequency allowable value range; the method comprises the steps that an OLT monitors an alternating current power value when a first online ONU registration activation stage carries out wavelength tuning in an intermediate frequency allowable value range, an intermediate frequency value corresponding to the monitored alternating current power value is obtained, and in the process of monitoring the wavelength tuning, the obtained intermediate frequency signal frequency value range meeting the performance requirement of a coherent receiver in the OLT is obtained.

In one embodiment, medium access controller 320 may further comprise: the conflict monitoring unit is used for judging that the ONU generates uplink data conflict if the monitored intermediate frequency signal is in the intermediate frequency allowable value range of the coherent receiver of the OLT and the uplink message carried by the signal light corresponding to the intermediate frequency signal meets at least one of the condition that the signal light cannot be analyzed correctly and the error rate is higher than the error rate threshold value; and the back-off notification unit is used for notifying the ONU to keep the working parameters corresponding to the alternating current power value points and carrying out back-off on the uplink data collision.

In some embodiments, the medium access Controller is different from a medium access Controller (MEDIA ACCESS Controller, MAC) chip in the PON system. That is, the medium access controller may be implemented according to corresponding software functional modules, which do not need to be solidified in the MAC chip, when implementing the functions described in the above embodiments. And, since there is also a difference between medium access controllers in different PON devices, it is not suitable for curing on a MAC chip.

According to the optical line terminal provided by the embodiment of the invention, after the medium access controller sends the downlink message to the ONU, the ONU is triggered to adjust the emission parameters of the optical signal until the wavelength of the adjusted optical signal is judged to fall into the intermediate frequency receiving range of the coherent receiver, so that the problems of uncertain working wavelength of the ONU in the uplink direction and wavelength drift of the ONU in the optical network system are solved.

It should be clear that the invention is not limited to the specific arrangements and processes described in the foregoing embodiments and shown in the drawings. For convenience and brevity of description, detailed descriptions of known methods are omitted herein, and specific working processes of the optical line terminal in the embodiment of the present invention may refer to corresponding working processes of the OLT in the embodiment of the coherent receiving method described in the foregoing combination embodiment, which are not repeated herein.

Fig. 7 shows a schematic structural diagram of an optical network unit according to an embodiment of the present invention. As shown in fig. 7, in one embodiment, the optical network unit ONU may include: a signal transmitting module 410, a signal receiving module 420, and a medium access controller 430.

The transmitting module 410 may include a transmitting parameter adjusting module 411 and a signal light transmitter 412. Specifically, the transmission parameter adjusting module 411 is configured to adjust a signal transmission parameter of an optical signal in response to receiving a downlink message from the OLT; and the signal optical transmitter 412 is configured to send an optical signal to the OLT according to the adjusted signal transmission parameter, so that after the optical signal and the intrinsic optical signal are coherently mixed, an intermediate frequency signal with a frequency value within an intermediate frequency allowable range is obtained.

The signal receiving module 420 is configured to receive the downlink message optical signal from the OLT and convert the downlink message optical signal into an electrical signal.

The medium access controller 430 may be configured to perform frame analysis on the downstream signal sent by the OLT, and complete frame sending of the upstream signal of the ONU.

In one embodiment, the emission parameter tuning module 411 may be specifically configured to: and adjusting signal emission parameters according to uplink signal light parameter information carried in the downlink message, wherein the uplink signal light parameter information is used for indicating the signal emission parameters capable of obtaining intermediate frequency signals with frequency values within an intermediate frequency allowable value range.

In one embodiment, medium access controller 430 may include a tuning range acquisition unit and a parameter setting unit.

The parameter adjustment range obtaining unit is configured to obtain an emission parameter adjustable range from uplink signal light parameter information carried by the downlink message, and output the emission parameter adjustable range to the emission parameter adjustment module 411; the emission parameter adjusting module 411 is further configured to adjust the signal emission parameter within the adjustable range of the emission parameter.

In this embodiment, the signal optical transmitter 412 is further configured to send an upstream message to the OLT using the adjusted signal transmission parameters.

In this embodiment, the parameter setting unit is configured to respond to receiving a feedback message of the uplink message, and use a signal transmission parameter corresponding to the uplink message as a signal transmission parameter in a normal operating state of the ONU.

Specifically, the feedback message of the upstream message is a feedback message sent to the ONU when the OLT receives the upstream message sent by the signal optical transmitter 412 and correctly analyzes the upstream message. That is, the feedback message of the upstream message is used to indicate that the OLT receives and correctly parses the upstream message.

In one embodiment, the emission parameter tuning module 411 may further include:

And the parameter adjusting unit is used for adjusting the signal transmission parameters for a plurality of times in a preset uplink wavelength range.

The signal light transmitter 412 is further configured to transmit an uplink message to the OLT using the signal light after each adjustment, where the uplink message carries adjustment information of the corresponding signal transmission parameter.

The transmitting parameter determining unit is further configured to determine a signal transmitting parameter and/or a transmitter operating parameter in a normal operating state of the ONU according to the adjustment information carried in the uplink message in response to receiving a feedback message of the uplink message, where the feedback message is used to indicate that the uplink message is correctly parsed.

In one embodiment, the adjustment information of the signal transmission parameter includes any one of the following information items corresponding to each adjustment: parameter setting of signal transmitting parameters, tuning frequency serial numbers, transmitting parameter adjusting directions, transmitting parameter adjusting values, parameter adjusting time and working parameters of a transmitter.

In one embodiment, the signal optical transmitter 412 is further configured to send registration information to the OLT in response to receiving a registration request sent by the OLT according to the adjusted signal transmission parameter; the medium access controller 430 may further include a parameter storage unit, configured to store the adjusted signal transmission parameter and the transmitter operation parameter in the ONU after the OLT is successfully registered according to the registration information; the parameter setting unit is used for setting the signal transmission parameter of the ONU in the normal working stage and the working parameter of the transmitter in the ONU in the normal working stage by using the stored signal transmission parameter and the stored working parameter of the transmitter.

According to the optical network unit provided by the embodiment of the invention, the problem that the working wavelength of the ONU in the uplink direction in the optical network system is uncertain and exceeds the intermediate frequency receiving range of the OLT coherent receiver is solved by adjusting the transmitting parameter of the optical signal and calibrating on line in response to receiving the downlink message issued by the OLT.

It should be clear that the invention is not limited to the specific arrangements and processes described in the foregoing embodiments and shown in the drawings. For convenience and brevity of description, detailed descriptions of known methods are omitted herein, and specific working procedures of the optical network unit in the embodiment of the present invention may refer to corresponding working procedures of the optical network unit in the embodiment of the signal processing method described in the foregoing embodiment, which is not described herein again.

Fig. 8 shows a schematic structural diagram of an optical network system according to an embodiment of the present invention. As shown in fig. 8, in one embodiment, the optical network system may include an optical line terminal OLT510 and an optical network unit ONU520.

The OLT is used for sending a downlink message to the optical network unit ONU, and the downlink message is used for triggering the ONU to adjust signal transmission parameters; the ONU is used for responding to the received downlink message, adjusting the signal transmission parameters of the optical signals and sending the optical signals to the OLT according to the adjusted signal transmission parameters; the OLT is also used for carrying out coherent mixing processing on the received optical signal and the intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal with a frequency value within an intermediate frequency allowable value range.

In the optical network system of the embodiment of the invention, the OLT can trigger the ONU to adjust the transmitting parameter and calibrate on line by sending the downlink message, thereby solving the problem that the working wavelength of the ONU in the uplink direction in the optical network system is uncertain and exceeds the intermediate frequency receiving range of the OLT coherent receiver.

The specific working process of the optical line terminal in the embodiment of the present invention may refer to the corresponding working process of the OLT in the embodiment of the coherent receiving method described in the foregoing embodiment; and a specific working process of the ONU according to the embodiment of the present invention, reference may be made to the corresponding working process of the optical network unit in the embodiment of the signal processing method described in the foregoing embodiment.

It should be clear that the invention is not limited to the specific arrangements and processes described in the foregoing embodiments and shown in the drawings. For convenience and brevity of description, detailed descriptions of known methods are omitted herein, and specific working processes of the systems, modules and units described above may refer to corresponding processes in the foregoing method embodiments, which are not repeated herein.

Fig. 9 is a block diagram illustrating an exemplary hardware architecture capable of implementing a computing device according to an embodiment of the invention. As shown in fig. 9, the computing device 900 includes an input device 901, an input interface 902, a central processor 903, a memory 904, an output interface 905, and an output device 906. The input interface 902, the central processor 903, the memory 904, and the output interface 905 are connected to each other through a bus 910, and the input device 901 and the output device 906 are connected to the bus 910 through the input interface 902 and the output interface 905, respectively, and further connected to other components of the computing device 900.

Specifically, the input device 901 receives input information from the outside, and transmits the input information to the central processor 903 through the input interface 902; the central processor 903 processes the input information based on computer-executable instructions stored in the memory 904 to generate output information, temporarily or permanently stores the output information in the memory 904, and then transmits the output information to the output device 906 through the output interface 905; output device 906 outputs the output information to the outside of computing device 900 for use by a user.

In one embodiment, the computing device 900 shown in fig. 9 may be implemented as a coherent receiving system, which may include: a memory configured to store a program; and a processor configured to run a program stored in the memory to perform the coherent reception method described in the above embodiment.

In one embodiment, the computing device 900 shown in fig. 9 may be implemented as a signal processing system that may include: a memory configured to store a program; and a processor configured to execute a program stored in the memory to perform the signal processing method described in the above embodiment.

The processes described above with reference to flowcharts may be implemented as computer software programs according to embodiments of the present invention. For example, embodiments of the invention include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program comprising program code for performing the method shown in the flowchart. In such embodiments, the computer program may be downloaded and installed from a network, and/or installed from a removable storage medium.

Those of ordinary skill in the art will appreciate that all or some of the steps, systems, functional modules/units in the apparatus, and methods disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between the functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed cooperatively by several physical components. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as known to those skilled in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computer. Furthermore, as is well known to those of ordinary skill in the art, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media.

It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.

Claims

1. A coherent reception method for an optical line terminal OLT, comprising:

Transmitting a downlink message to an Optical Network Unit (ONU), wherein the downlink message is used for triggering the ONU to adjust signal transmission parameters;

In response to receiving the adjusted optical signal, performing coherent mixing processing on the optical signal and an intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal;

monitoring an alternating current power value of a photocurrent signal output after photoelectric detection of an intermediate frequency signal by a coherent receiver in the OLT, and monitoring the change of the alternating current power value detected by a photoelectric detector in the coherent receiver to obtain the frequency value of the intermediate frequency signal received by the coherent receiver;

And judging whether the frequency value of the intermediate frequency signal is within an intermediate frequency allowable value range, and returning to the step of sending a downlink message to an Optical Network Unit (ONU) to send a parameter adjusting instruction carrying working parameters to the ONU when the frequency value of the intermediate frequency signal is not within the intermediate frequency allowable value range.

2. The method of claim 1, wherein the sending the downlink message comprises:

Determining uplink signal optical parameter information according to at least one of an intermediate frequency allowable value range and a frequency value of the intrinsic optical signal;

transmitting a downlink message carrying the uplink signal light parameter information;

The intermediate frequency allowable value range is a frequency value range of an intermediate frequency signal which is determined in advance according to the type of the coherent receiver of the OLT and can meet the performance requirement of the coherent receiver.

3. The method of claim 2, wherein the determining the upstream signal optical parameter information according to at least one of the intermediate frequency allowed value range and the frequency value of the intrinsic optical signal comprises:

Taking a frequency channel value or a wavelength channel value corresponding to the frequency value of the intrinsic optical signal as the uplink signal optical parameter information; or alternatively

Taking a target emission parameter value corresponding to the frequency value of any intermediate frequency signal in the intermediate frequency allowable value range as the uplink signal light parameter information; or alternatively

The emission parameter adjustment direction and the emission parameter adjustment value obtained through calculation according to the frequency value of the intrinsic optical signal and the frequency value of the intermediate frequency signal are used as the uplink signal optical parameter information;

or determining an adjustable range of the transmission parameter according to the frequency value of the intrinsic optical signal and the bandwidth of the coherent receiver of the OLT, and taking the adjustable range of the transmission parameter as the optical parameter information of the uplink signal.

4. The method of claim 1, further comprising, prior to responding to receiving the adjusted optical signal:

responding to the received uplink message from the ONU, and if the uplink message is correctly analyzed, sending a feedback message of the uplink message, wherein the feedback message is used for indicating that the uplink message is correctly analyzed;

And if the uplink message carries the adjustment information of the ONU adjustment signal transmission parameters, carrying the adjustment information in the feedback message.

5. The method of claim 4, wherein if the number of correctly parsed uplink messages within a specified time period is greater than 1, the sending a feedback message for the uplink message further comprises:

For any uplink message which is correctly analyzed, sending the feedback message; or alternatively

The feedback message is sent aiming at selecting one correctly resolved uplink message with the lowest error rate; or alternatively

And sending the feedback message aiming at the uplink message with the frequency value of the corresponding intermediate frequency signal closest to the optimal intermediate frequency value, wherein the optimal intermediate frequency value is an intermediate frequency value in the intermediate frequency allowable value range of the coherent receiver in the OLT.

6. The method according to claim 1, wherein after sending the downstream message to the optical network unit ONU, further comprising:

determining a first corresponding relation between the alternating current power value and the intermediate frequency value according to the alternating current power value and the intermediate frequency signal frequency value;

according to the first corresponding relation and the frequency value in the intermediate frequency allowable value range, calculating an alternating current power value point corresponding to the frequency value in the intermediate frequency allowable value range;

determining working parameters corresponding to the alternating current power value points, and sending parameter adjusting instructions carrying the working parameters to the ONU so that the ONU adjusts the working parameters of a transmitter according to the carried working parameters;

7. The method of claim 6, wherein the determining an operating parameter corresponding to the ac power value point comprises:

monitoring an uplink message sent by the ONU after signal transmission parameters are adjusted, wherein the uplink message carries parameter adjustment time and working parameters used in the parameter adjustment time;

Determining a second corresponding relation between the alternating current power value and the monitoring time through the monitored alternating current power value and the corresponding monitoring time;

Calculating a monitoring time corresponding to the alternating current power value point by utilizing the alternating current power value point corresponding to the frequency value in the intermediate frequency allowable value range and the second corresponding relation to obtain a monitoring time calculated value;

Determining parameter adjusting time corresponding to the monitoring time calculated value, and obtaining parameter adjusting time calculated value corresponding to the alternating current power value point;

And taking the parameter adjusting time as the working parameter used when the parameter adjusting time is calculated as the parameter corresponding to the alternating current power value point.

8. The method of claim 1, wherein the ONU is a first-on-line ONU in an optical distribution network, the optical distribution network being located between the OLT and the ONU; the method further comprises the steps of:

carrying working parameters of the corresponding alternating current power value points of the intermediate frequency allowable value range in the registration activation downlink message sent to other ONU in the optical distribution network;

when the working parameters corresponding to the alternating current power value points in the intermediate frequency allowable value range are multiple groups, selecting the working parameters corresponding to the intermediate frequency values in the intermediate frequency allowable value range;

and the OLT monitors the alternating current power value of the first online ONU in the registration activation stage for wavelength tuning, acquires an intermediate frequency value corresponding to the monitored alternating current power value, and in the process of monitoring the wavelength tuning, acquires the frequency value range of an intermediate frequency signal meeting the performance requirement of a coherent receiver in the OLT.

9. The method of claim 6, further comprising:

If the monitored frequency value of the intermediate frequency signal is within the intermediate frequency allowable value range of the coherent receiver of the OLT, and the uplink message carried by the signal light corresponding to the intermediate frequency signal meets at least one of the condition that the signal light cannot be analyzed correctly and the error rate is higher than the error rate threshold, judging that the ONU generates uplink data conflict;

And notifying the ONU to maintain the working parameters corresponding to the alternating current power value point and carrying out back-off on the uplink data conflict.

10. A signal processing method for an optical network unit ONU, comprising:

adjusting signal emission parameters of the optical signals in response to receiving the downlink message from the optical line terminal OLT;

And sending an optical signal to the OLT according to the adjusted signal emission parameters, so that after the optical signal and the intrinsic optical signal are subjected to coherent mixing processing, an intermediate frequency signal is obtained, the OLT monitors an alternating current power value of a photocurrent signal output after photoelectric detection of the intermediate frequency signal by a coherent receiver in the OLT, monitors the alternating current power value change detected by a photoelectric detector in the coherent receiver to obtain an intermediate frequency signal frequency value received by the coherent receiver, judges whether the intermediate frequency signal frequency value is in an intermediate frequency allowable value range, receives a downlink message sent by the OLT when the intermediate frequency signal frequency value is not in the intermediate frequency allowable value range, so as to obtain a parameter adjusting instruction carrying the working parameters sent by the OLT, and returns the step of adjusting the signal emission parameters of the optical signal in response to receiving the downlink message from the optical line terminal OLT.

11. The method of claim 10, wherein the adjusting the signal emission parameter of the optical signal comprises:

Adjusting signal emission parameters according to uplink signal light parameter information carried in the downlink message, wherein the uplink signal light parameter information is used for indicating the signal emission parameters capable of obtaining intermediate frequency signals with frequency values within the intermediate frequency allowable value range;

12. The method of claim 10, wherein the adjusting the signal emission parameter of the optical signal comprises:

Acquiring an adjustable range of the emission parameters from the uplink signal light parameter information carried by the downlink message, and adjusting the signal emission parameters in the adjustable range of the emission parameters;

transmitting an uplink message to the OLT by using the adjusted signal transmission parameters;

Responding to the feedback information of the uplink information, and taking the signal transmission parameter corresponding to the uplink information as the signal transmission parameter in the normal working state of the ONU;

The interval time of two adjacent times of adjustment is longer than the message round trip time between the OLT and the ONU, and the frequency value corresponding to the value range of the adjustment step length of the signal transmission parameter is smaller than the intermediate frequency allowable value range of the coherent receiver in the OLT.

13. The method of claim 10, wherein the adjusting the signal emission parameter of the optical signal comprises:

Adjusting signal emission parameters for a plurality of times in a preset uplink wavelength range;

transmitting uplink information to the OLT by utilizing the signal light after each adjustment, wherein the uplink information carries adjustment information of corresponding signal emission parameters;

And responding to the received feedback message of the uplink message, and determining a signal transmission parameter and/or a transmitter working parameter under the normal working state of the ONU according to the adjustment information carried in the uplink message, wherein the feedback message is used for indicating that the uplink message is correctly analyzed.

14. The method of claim 13, wherein the adjustment information of the signal transmission parameter includes any one of the following information items corresponding to each of the adjustments:

Parameter setting of signal transmitting parameters, tuning frequency serial numbers, transmitting parameter adjusting directions, transmitting parameter adjusting values, parameter adjusting time and working parameters of a transmitter.

15. The method of claim 10, further comprising:

transmitting registration information to the OLT in response to receiving a registration request transmitted by the OLT according to the adjusted signal transmission parameters;

after the OLT is successfully registered according to the registration information, the adjusted signal transmission parameters and the working parameters of the transmitters in the ONU are stored;

And setting the signal transmission parameters of the ONU in the normal working stage and the working parameters of the transmitter in the ONU in the normal working stage by using the stored signal transmission parameters and the stored working parameters of the transmitter.

16. An optical line terminal, comprising:

The medium access controller module is used for sending a downlink message to the Optical Network Unit (ONU), and the downlink message is used for triggering the ONU to adjust signal transmission parameters;

The signal receiving module is used for performing coherent mixing processing on the optical signal and the intrinsic optical signal in response to receiving the adjusted optical signal to obtain an intermediate frequency signal;

The signal receiving module is also used for monitoring the alternating current power value of the photocurrent signal output after the photoelectric detection of the intermediate frequency signal by the coherent receiver in the OLT, and monitoring the change of the alternating current power value detected by the photoelectric detector in the coherent receiver to obtain the frequency value of the intermediate frequency signal received by the coherent receiver;

And the medium access controller module is also used for judging whether the frequency value of the intermediate frequency signal is in an intermediate frequency allowable value range, and returning to the step of sending a downlink message to the Optical Network Unit (ONU) under the condition that the frequency value of the intermediate frequency signal is not in the intermediate frequency allowable value range so as to send a parameter adjusting instruction carrying working parameters to the ONU.

17. An optical network unit comprising:

the emission parameter regulation module is used for responding to the received downlink message from the optical line terminal OLT and adjusting the signal emission parameter of the optical signal;

The signal transmitting module is used for transmitting an optical signal to the OLT according to the adjusted signal transmitting parameters, so that an intermediate frequency signal is obtained after the optical signal and the intrinsic optical signal are subjected to coherent mixing processing, the OLT monitors an alternating current power value of a photocurrent signal output after photoelectric detection of the intermediate frequency signal by a coherent receiver in the OLT, monitors the alternating current power value change detected by a photoelectric detector in the coherent receiver to obtain an intermediate frequency signal frequency value received by the coherent receiver, and judges whether the frequency value of the intermediate frequency signal is in an intermediate frequency allowable value range;

And the signal receiving module is used for receiving the downlink message sent by the OLT under the condition that the frequency value of the intermediate frequency signal is not in the intermediate frequency allowable value range so as to obtain a parameter adjusting instruction carrying working parameters sent by the OLT, and returning to the step of adjusting the signal transmitting parameters of the optical signal by the transmitting parameter adjusting module in response to receiving the downlink message from the optical line terminal OLT.

18. An optical network system comprises an Optical Line Terminal (OLT) and an Optical Network Unit (ONU), wherein,

The OLT is configured to send a downlink message to an optical network unit ONU, where the downlink message is used to trigger the ONU to adjust a signal transmission parameter;

the ONU is used for responding to the received downlink message, adjusting the signal transmission parameters of the optical signals and sending the optical signals to the OLT according to the adjusted signal transmission parameters;

The OLT is also used for carrying out coherent mixing processing on the received optical signals and the intrinsic optical signals adopted by the OLT to obtain intermediate frequency signals;

the OLT is also used for monitoring the alternating current power value of the photocurrent signal output after the photoelectric detection of the intermediate frequency signal by the coherent receiver in the OLT, and monitoring the alternating current power value change detected by the photoelectric detector in the coherent receiver to obtain the intermediate frequency signal frequency value received by the coherent receiver;

The OLT is further configured to determine whether the frequency value of the intermediate frequency signal is within an intermediate frequency allowable value range, and return to a step of sending a downlink message to the optical network unit ONU when the frequency value of the intermediate frequency signal is not within the intermediate frequency allowable value range, so as to send a parameter adjustment instruction carrying an operating parameter to the ONU.

19. A coherent reception system comprising a memory and a processor;

The memory is used for storing executable program codes;

the processor is configured to read executable program code stored in the memory to perform the coherent reception method of any one of claims 1 to 9.

20. A signal processing system comprising a memory and a processor;

The memory is used for storing executable program codes;

The processor is configured to read executable program code stored in the memory to perform the signal processing method of any one of claims 10 to 15.