CN113055097A

CN113055097A - Coherent receiving method, signal processing method and system

Info

Publication number: CN113055097A
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: 2021-06-29
Anticipated expiration: 2039-12-27
Also published as: CN113055097B

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: sending 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 the received adjusted optical signal, carrying out coherent mixing processing on the optical signal and the intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal of which the frequency value is within the range of the intermediate frequency allowable value.

Description

Coherent receiving 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 of Network bandwidth for transmitting a large amount of data by using a Network is continuously increased, the capacity of an Optical fiber transmission access Network is continuously increased, a 10G Passive Optical Network (PON) technology is gradually commercialized, and a 50G PON or higher-rate PON system will become the direction of the development of a next-generation PON system in the future.

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

In a PON Network, when an Optical Line Terminal (OLT) performs coherent reception on an Optical signal from an Optical Network Unit (ONU), since wavelengths of an intrinsic light and a signal light are uncertain, a frequency difference between the intrinsic light and an upstream signal light (i.e., a frequency value of an intermediate frequency signal) is likely to exceed a coherent mixing range, thereby causing a problem of signal detection failure.

Disclosure of Invention

Embodiments of the present invention provide a coherent reception method, a signal processing method, and a system, which can implement high-sensitivity coherent reception in a passive optical network system.

In a first aspect, an embodiment of the present invention provides a coherent reception method, which is used for an optical line terminal OLT, and includes: sending 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 the received adjusted optical signal, carrying out coherent mixing processing on the optical signal and the intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal of which the frequency value is within the range of the intermediate frequency allowable value.

In a second aspect, an embodiment of the present invention provides a signal processing method for an optical network unit ONU, including: responding to a received downlink message from an Optical Line Terminal (OLT), and adjusting a signal transmission parameter of an optical signal; and sending the optical signal to the OLT according to the adjusted signal emission parameter so as to obtain an intermediate frequency signal with the frequency value within the range of the intermediate frequency allowable value after the optical signal and the intrinsic optical signal are subjected to coherent mixing processing.

In a third aspect, an embodiment of the present invention provides an optical line terminal, including: the media access controller module is used for sending a downlink message to the ONU, and the downlink message is used for triggering the ONU to adjust the signal transmission parameters; and the signal receiving module is used for responding to the received adjusted optical signal and carrying out coherent mixing processing on the optical signal and the intrinsic optical signal to obtain an intermediate frequency signal of which the frequency value is within the range of the intermediate frequency allowable value.

In a fourth aspect, an embodiment of the present invention provides an optical network unit, including: the transmitting parameter regulating and controlling module is used for responding to the received downlink message from the OLT and regulating the signal transmitting parameters of the optical signals; 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 of which the frequency value is within the range of the intermediate frequency allowable value 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 optical line terminal OLT and an optical network unit ONU, where the OLT is configured to send a downlink message to the optical network unit 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 parameter of the optical signal and sending the optical signal to the OLT according to the adjusted signal transmission parameter; 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 of which the frequency value is within the range of the intermediate frequency allowable value.

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 adapted 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 used for reading the executable program codes stored in the memory to execute the signal processing method.

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 optical network unit in the uplink direction 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, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit 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 flow chart of a coherent reception method according to an embodiment of the invention.

Fig. 3a is a schematic diagram illustrating 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 shows a schematic diagram of the variation of the ac power value with time in the embodiment of the present invention.

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

Fig. 6 shows a schematic structural diagram 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 embodiments of the present invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation. 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 present invention by illustrating examples of the present invention.

In the embodiment of the invention, in the coherent receiving technology, the received signal light and the intrinsic light generated by the intrinsic laser are mixed by a mixer to obtain an intermediate frequency signal which changes regularly with the frequency, the phase and the amplitude of the signal light, 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 data information loaded on the signal light. For the intensity-modulated signal light, the optical signal after coherent reception is a mixing signal of the signal light and the intrinsic light with larger optical power, the optical signal power is enhanced, and the requirement of high receiving sensitivity in an optical network system can be met.

In a PON network, the operating wavelengths in the upstream direction of different ONUs are not completely the same, and due to the influence of the operating conditions of the laser transmitters in the ONUs, the operating wavelength in the upstream direction of the same ONU may also generate wavelength drift at different times. Due to the wavelength uncertainty, coherent reception in the uplink direction may cause the problem that the wavelength difference between the intrinsic light and the uplink signal exceeds the coherent mixing range, resulting in failure of signal detection.

Embodiments of the present invention provide a coherent receiving method, a signal processing method, and a system, so as to solve a problem that a wavelength difference between intrinsic light and an uplink signal exceeds a coherent mixing range, thereby causing a signal detection failure. 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 on the office side and one or more ONUs on the subscriber side, such as ONU1, ONU2, and … … ONUn, where n is an integer greater than or equal to 1. Between the OLT and the ONUs, an Optical Distribution Network (ODN) may include passive devices such as Optical fibers and Optical splitters. The ODN is used to provide an optical transmission medium for the physical connection between the OLT and the ONU. The PON system employs a point-to-multipoint network topology. As an example, the OLT may be located at a communication facility (e.g., a central office) of an access provider as a central node of the passive optical network, and the ONUs may be located at or near a location of an access subscriber as subscriber nodes.

Fig. 2 shows a flow chart of a coherent reception method according to an embodiment of the invention. In one embodiment, a coherent reception method may be used for the OLT, and the coherent reception method includes the following steps S110 to S120.

Step S110, sending a downlink message to an Optical Network Unit (ONU), wherein the downlink message is used for triggering the ONU to adjust signal transmission parameters. Step S120, in response to receiving the adjusted optical signal, performing coherent mixing processing on the optical signal and the intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal having 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, the performance requirement of a coherent receiver is met, and the problem that the working wavelength in the uplink direction in a passive optical network system is uncertain and exceeds the intermediate frequency receiving range of a coherent receiver in the OLT is solved.

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

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 temperature control device or the wavelength locking device of the laser chip. That is, the OLT employs an intrinsic light source that is wavelength-stable. In a PON system, the Guard Time between upstream burst packets sent by different ONUs is very short, and if an adjustable laser is used as an intrinsic light source in an OLT and an upstream signal is tuned by tuning the wavelength of the adjustable laser when receiving the wavelength of a signal from different ONUs, the wavelength tuning Time of the adjustable laser is required to be very fast, which is difficult to be satisfied by an adjustable laser, and the fast adjustable laser has a high cost. In comparison, the OLT in the embodiment of the invention adopts the intrinsic light source with stable wavelength, so that the cost is lower and the realization is easier.

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

In this embodiment, the intermediate frequency signal light that meets the performance requirements 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 the registration activation phase; or the ONU is in a normal working stage; or monitoring that the ONU is in a normal working stage and the wavelength drifts, and sending a downlink message to the ONU to trigger the ONU to adjust the signal transmission parameters.

The registration flow of the ONU in the registration activation phase is briefly described below. When an ONU is just powered on and is not registered, the ONU is in an initial stage state, namely O1 state for short, and when the ONU in O1 state receives downstream, the ONU is transferred to a standby state, namely O2 state for short; the ONU in the O2 state performs related configuration according to network parameters carried in the downstream, wherein the related configuration comprises but is not limited to a delimiter, a power mode, a preset equalization delay and the like, and transfers to a serial number state, namely an O3 state; the OLT sends a Serial Number discovery Serial-Number Request message to the ONU in the O3 state, and the Serial Number discovery Serial-Number Request 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 shifts to a ranging state, namely an O4 state for short, after passing through the received ONU-ID; different ONU sending signals are kept synchronous when reaching the OLT, therefore, each ONU needs an equalizing Time delay, the equalizing Time delay can be measured by the distance between the ONU and the OLT by the OLT, and after receiving the equalizing Time delay Ranging _ Time message from the OLT, the ONU executes an equalizing Time delay value needing to be inserted and then shifts to an operation state, namely an O5 state for short. At this time, the ONU completes the registration process, and may send uplink data and Physical Layer Operation Administration and Maintenance (PLOAM) messages under the control of the OLT.

According to the coherent receiving method of the embodiment of the invention, the ONU can be triggered to adjust the signal emission parameters at the ONU registration activation stage, and the signal emission parameters of the ONU can be adjusted online according to the monitored ONU wavelength drift when the PON system works normally, so that the ONU working wavelength 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 transmission parameters are adjusted, the signal transmission parameters can be directly adjusted, and the aim of adjusting the wavelength of the transmitted light signals or adjusting the frequency of the transmitted light signals can be achieved by adjusting the working parameters of the transmitters in the ONU.

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

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

And 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. And S112, sending a downlink message carrying the optical parameter information of the uplink signal.

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

As an example, when 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, for example, smaller than the signal sampling frequency and the difference from the signal sampling frequency is larger than the frequency difference threshold; when the type of the coherent receiver is heterodyne coherent, the intermediate frequency value of the heterodyne coherent receiver may 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. And determining the intermediate frequency value of the coherent receiver according to the type of the coherent receiver, namely the intermediate frequency allowable value of the coherent receiver.

In step S112, the downlink message may be a PLOAM message. When the downlink message carries the optical parameter information of the uplink signal, the optical parameter information of the uplink signal can be realized by modifying the existing downlink PLOAM message format or adding a 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 downlink broadcast PLOAM message may include: an uplink Physical Layer Overhead (PLOu), an assignment logical number message Assign _ ONU-ID message, a Registration Request message, a Calibration Request message Calibration _ Request message, or a Coherent optical working channel Coherent _ working _ channel message.

Table 1 below shows a message format definition of a downlink broadcast PLOAM message, taking a Coherent _ working _ channel message as an example.

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

As can be seen from the above description, in an embodiment, the step S111 may specifically include: taking the frequency channel value or the wavelength channel value of the intrinsic optical signal as the optical parameter information of the uplink signal; or, taking a target transmitting parameter value corresponding to the frequency value of any intermediate frequency signal within the intermediate frequency allowable value range as the optical parameter information of the uplink signal; 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 the range of the intermediate frequency allowable value, or an optimal value may be preset in the OLT according to the coherent reception performance of the coherent receiver in the OLT. Illustratively, the target transmission parameter value may be any one of a frequency value of an optical signal transmitted by the ONU, a wavelength value of the optical signal, or a transmitter operating 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 can select to send the uplink signal optical parameter information in a frequency value or wavelength value mode according to the calibration 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 an intrinsic optical signal, the ONU may set the wavelength of the transmission 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 uplink signal optical parameter information carried in the downlink message is a frequency value of the intrinsic optical signal and a frequency value of the intermediate frequency signal within an intermediate frequency allowable value range, the ONU may calculate the frequency value of the optical signal emitted by the ONU according to the two values, specifically, a difference value between the frequency value of the optical signal emitted by the ONU and the frequency value of the intrinsic optical signal is within the intermediate frequency allowable value 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 transmission parameter to meet the performance requirement of the coherent receiver according to the uplink signal optical parameter information carried in the downlink message, so that the optical signal transmitted by the ONU is efficiently and accurately calibrated.

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

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

Further, when the frequency value of the intermediate frequency signal corresponding to the signal transmission parameter adjustment is within the frequency range of the bandwidth of the OLT coherent receiver and the range of the intermediate frequency allowed value, the OLT may correctly analyze the uplink message transmitted by the optical signal and send the uplink message to the ONU.

In an embodiment, after the ONU sends the upstream message to the OLT, if a 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 a receiver bandwidth of the OLT.

In the following, 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 bandwidth of the OLT coherent receiver is introduced through fig. 3a and fig. 3 b.

Fig. 3a shows a schematic diagram of an ONU adjusting the wavelength of an optical signal in an embodiment, and fig. 3b shows a schematic diagram of an ONU adjusting the wavelength of an optical signal in another embodiment. In FIGS. 3a and 3b, λ_{s_c}Representing the wavelength value, d λ, of the current optical signal_sIndicating a wavelength adjustment interval value, i.e. a wavelength adjustment step length, lambda_{s_x}Indicating the wavelength value, lambda, of the conditioned optical signal_{LO_}Which represents the wavelength value of the intrinsic optical signal employed by the OLT. Δ f_IFRepresenting the range of permissible intermediate frequencies, Δ f, of a coherent receiver_IFAnd/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 ranges corresponding to the allowable range of intermediate frequencies can be distributed at the wavelength λ_{LO_c}On both sides of the base.

In one embodiment, the wavelength value λ is based on the intrinsic optical signal_{LO_c}Calculating the frequency range of the bandwidth of the OLT coherent receiver to obtain the wavelength adjustment upper limit value lambda_max(ii) a According to the wavelength value lambda of the intrinsic optical signal_{LO_c}Calculating the frequency range of the bandwidth of the OLT coherent receiver to obtain the lower limit value lambda of the wavelength adjustment_min。

In fig. 3a, when the coherent receiver is a heterodyne coherent detection receiver, the allowable range of the intermediate frequency can be located at the wavelength λ of the intrinsic optical signal_{LO_c}In the long wavelength direction or in the short wavelength direction. The long wavelength direction is greater than the wavelength value lambda_{LO_c}The short wavelength direction is less than the wavelength value lambda_{LO_c}In the wavelength direction of (1).

Specifically, the wavelength value λ of the present optical signal_{s_c}Adjustable in the long wavelength direction to a wavelength adjustment upper limit lambda_maxWavelength adjustment upper limit value λ_maxGreater than the wavelength value lambda of the intrinsic light signal_{LO_c}Wavelength value of the current optical signal λ_{s_c}Can be adjusted to a lower limit value lambda of wavelength adjustment in the short wavelength direction_minWherein the wavelength is adjusted to an upper limit value λ_maxAnd wavelength adjustment lower limit lambda_minThe difference between may be less than twice the OLT coherent receiver bandwidth.

In this embodiment, the ONU may be smaller thanAdjusting the wavelength value of the optical signal within a frequency range of twice the bandwidth of the OLT coherent receiver, wherein a central value of the frequency range of less than twice the bandwidth of the OLT coherent receiver may be the wavelength value λ of the intrinsic optical signal_{LO_c}。

Specifically, the ONU may first select the long wavelength direction to adjust the wavelength of the uplink signal, and adjust the upper limit λ if the wavelength is adjusted_maxIf the wavelength of the uplink signal light does not fall within the range of the intermediate frequency allowable value, the wavelength of the uplink signal light can be adjusted in the short wavelength direction until the adjusted wavelength λ of the uplink signal light reaches_{s_x}Falling within the range of the intermediate frequency allowance.

Similarly, the ONU may first select a short wavelength direction to adjust the wavelength of the uplink signal, and adjust the upper limit λ if the wavelength is adjusted_minIf the wavelength of the uplink signal light is not within the range of the intermediate frequency allowable value, the wavelength of the uplink signal light can be adjusted to the long wavelength direction until the adjusted wavelength λ of the uplink signal light is adjusted_{s_x}Falling within the range of the intermediate frequency allowance.

As shown in FIG. 3b, when the OLT uses the homodyne coherent detection receiver, the wavelength value λ of the current optical signal_{s_c}With the wavelength value lambda of the intrinsic optical signal_{LO_c}The difference lies within the frequency range of the OLT coherent receiver bandwidth. The adjustment process of the signal emission parameters is the same as or equivalent to the adjustment process of the signal light wavelength in fig. 3a, and is not described herein again.

In the above-described fig. 3a and 3b, the wavelength adjustment interval d λ in the ONU_sNeeds to satisfy d λ_s＜ΔfI_IFThe condition of/c, i.e. the range of the wavelength adjustment step value should be smaller than the wavelength range corresponding to the range of the intermediate frequency allowed value of the coherent receiver.

In the above embodiment described with reference to fig. 3a and 3b, the ONU may adjust the signal transmission parameter within the adjustable range of the transmission parameter 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 emitted by the ONU need calibration and calibration, and the requirement on calibration lattice point is smaller. For example, the emission parameter adjustment value in the ONU, for example, the wavelength adjustment value is set to be 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 achieving the 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 the preset error threshold. That is to say, the scaling lattice point of the transmitter in the ONU can satisfy the condition of less than 2 times the bandwidth of the OLT coherent receiver, and the scaling accuracy satisfies the condition of the requirement of the coherent receiver on the receiving performance.

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 calibrate a large number of wavelength channels. For example, a coherent receiver with a 50GHz bandwidth, 2 times the bandwidth of the OLT coherent receiver corresponds to an O-band wavelength range of about 0.7 nm.

In order to further reduce the calibration requirement, the downlink message of the OLT may not carry the parameter information of the uplink signal. After the ONU receives the downlink message, the ONU can perform blind adjustment on the transmission optical parameter value, and the OLT determines the frequency difference value between the uplink optical signal adjusted by the ONU and the OLT intrinsic optical signal, namely whether the intermediate frequency signal frequency value falls within the intermediate frequency allowable value range or not, by receiving and correctly analyzing the uplink message sent by the ONU. And if the OLT receives and correctly analyzes the uplink message sent by the ONU, the frequency value of the intermediate frequency signal is within the range of the intermediate frequency allowable value.

In one embodiment, the coherent reception method may further include: s131, responding to the received uplink message from the ONU, if the uplink message is correctly analyzed, sending a feedback message aiming at the uplink message, wherein the feedback message is used for indicating that the uplink message is correctly analyzed; and S132, if the uplink message carries the adjustment information of the ONU adjustment signal transmission parameters, carrying the adjustment information in the feedback message.

In one step, the uplink message may or may not carry the adjustment information of the signal transmission parameters. 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 wavelength of the uplink optical signal is adjusted next time, and the parameter value of the adjusted uplink optical signal or the working parameter value of the adjusted transmitter is determined according to the correctly analyzed uplink message.

In an embodiment, if the uplink message carries the adjustment information for the ONU to adjust the signal transmission parameter, 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 time sequence number. The transmission parameter setting value may include any one of the following information items: the adjusted wavelength value of the optical signal, the adjusted frequency value of the optical signal and the adjusted working parameters of the transmitter.

In the embodiment of the invention, the ONU adjusts the signal transmission parameters and records the adjustment information in the uplink message, and the OLT receives and correctly analyzes the uplink message, then records the adjustment information and informs the ONU of the adjustment information.

Further, after the ONU is restarted due to power failure, 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, thereby reducing the wavelength adjustment time at the registration activation stage of the ONU.

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

As an example, the OLT sends downstream messages and monitors the ONUs for upstream messages. And if only one uplink message is received and the uplink message is correctly analyzed within the specified time length, and 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 range of the intermediate frequency allowable value, when the OLT monitors a plurality of uplink messages and correctly analyzes the uplink messages reported by a plurality of ONUs within a specified time, the OLT may select to send adjustment information carried by the middle uplink message, and send a feedback message of the selected uplink message to the ONUs.

As an example, when the OLT monitors and correctly parses two uplink messages within a specified duration, the adjustment information carried in any new uplink message of the two uplink messages is sent to the ONU through the 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 adjusting the signal transmission parameter each time may be less than the message round-trip time between the ONU and the OLT.

In an embodiment, after the OLT sends a feedback message for the uplink message to the ONU, the ONU may set the signal transmission parameter of the ONU in the normal working stage according to the adjustment information of the signal transmission parameter carried in the feedback message. And determining the working parameters of the transmitter in the normal working stage of the ONU according to the signal transmission parameters in the normal working stage.

In the embodiment of the invention, when the downlink message sent by the OLT end does not carry the uplink signal parameter information, and the ONU triggers and adjusts the signal transmission parameter, the signal transmission parameter is adjusted in the preset uplink wavelength range, and the adjusted optical signal is used for transmitting the uplink message carrying the adjustment information of the signal transmission parameter to the OLT. 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. And if the performance requirement of the coherent receiver is met, the ONU is informed to set the signal emission parameters and the working parameters of the transmitter in the normal working stage according to the adjustment information of the signal emission parameters, and the optical signals emitted by the ONU in the normal working stage are subjected to coherent reception. In the method, the OLT does not need to adopt a tunable laser as an intrinsic light source, so that the calibration and calibration requirements and the quick response requirements of the OLT on the emitted light signals are reduced, and compared with the use of a quick tunable laser, the cost can be effectively saved.

The coherent receiving method of the embodiment of the present invention may further utilize a photoelectric detector in the coherent receiver to perform photoelectric detection on the intermediate frequency signal and then output an ac power value, and determine a corresponding relationship between the output ac power value and the frequency value of the intermediate frequency signal, so as to determine an ac power value point corresponding to the intermediate frequency allowable value by utilizing the intermediate frequency allowable value and the corresponding relationship; 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 of the variation of the detected ac power value with the if signal will be briefly described below. A mixer in the coherent receiver can perform frequency mixing processing on a received optical signal and a local oscillator signal adopted by an OLT to obtain an intermediate frequency signal, and a photoelectric detector outputs an optical current signal after detecting the intermediate frequency signal.

As an example, the mixer may be, for example, a 180-degree optical mixer, i.e., a 2 × 2 coupler with two-port input and two-port output, and the optical signals at the output are 180 degrees out of phase. In practical applications, the type of the mixer is not particularly limited.

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

In the above expressions (1) and (2),

representing the optical field distribution, omega, of the intrinsic optical signal_LOShow bookThe frequency of the optical signal is characterized,

representing the phase of the intrinsic optical signal, A_LORepresents the power of the intrinsic optical signal;

representing the optical field distribution, omega, of the upstream signal light_sWhich represents the frequency of the upstream optical signal,

representing the phase of the upstream optical signal, A_sRepresenting the power value of the upstream optical signal.

In one embodiment, the ac power value of the photocurrent signal output after being detected by the photodetector can be expressed as the following expression (3).

In the above expression (3), I (t) represents a photocurrent value varying with the detection time, A_LORepresenting the power of the intrinsic optical signal, A_sRepresenting the power of the optical signal. Δ ω t represents the frequency of the intermediate frequency signal that varies with time, and Δ ω represents the frequency of the intermediate frequency signal, i.e., the frequency ω of the optical signal_sWith the frequency omega of the intrinsic optical signal_LOThe amount of frequency offset between the two,

indicating the phase of the intermediate frequency signal, i.e. of the optical signal

Phase with the intrinsic optical signal

The phase offset between.

Due to the power value A of the intrinsic optical signal_LOFor continuous light change over time to a constant value of DCFiltered by a blocking circuit and the power A of uplink signal light_sWeaker negligible, the above expression (3) can be simplified to

In one embodiment, the coherent receiver bandwidth frequency response curve H (ω) may be used to represent a coherent receiver receiving power response function with frequency, that is, two paths of 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' (Δ ω) and H (ω) satisfy the condition

H' (ω) represents a receiver current frequency response curve determined by the bandwidth of the coherent receiver, i.e., a response curve of the magnitude of the receiver output current with the magnitude of the frequency value of the input optical signal, which is proportional to the frequency response curve H (ω) of the bandwidth (power) of the coherent receiver to the power of 1/2. In this embodiment, the frequency value of the optical signal input to the receiver after passing through the mixer is the frequency value Δ ω of the intermediate frequency signal.

As an example, the photocurrent expressed by the above expression (4) may be set as the monitor current, i.e., I (t) ═ I_r1(t), the power after the ac power detection can be expressed as the following expression (6):

in the above expression (6), R represents an equivalent load resistance of the photodetector, and P_AC+DCIndicating photoelectric probeTotal power value, P, detected by the detector_ACRepresenting the AC power component, P, of the detected total power value_DCThe dc power component in the total power value is represented, and the same symbols in expression (6) and expressions (1) to (5) above represent the same meanings, and are not described herein again.

Further, the ac power monitoring may be after the balance detection, in the above expression (6)

And

by the balanced detection cancellation, the photocurrent at this time can be expressed as the following expression (7).

In the same way, can obtain

Wherein, the same symbols in the expression (7) and the above expressions (1) to (5) represent the same meanings, and are not described herein again.

As can be seen from the description of the above embodiments, when the ONU adjusts the signal transmission parameter in the uplink wavelength range, for example, the wavelength is tuned, the intermediate frequency value of the intermediate frequency signal detected in the OLT changes correspondingly according to the tuned wavelength, and the ac power value P after the ac power detection can be obtained_ACThe variation curve of (2) is consistent with the bandwidth frequency response curve of the coherent receiver. That is, the coherent receiver photodetector has a filtering characteristic for the received coherent intermediate frequency optical signal due to its frequency response range. Therefore, by monitoring the value P of the AC power detected by the photodetector in the coherent receiver_ACAnd obtaining the frequency value of the received intermediate frequency signal of the coherent receiver by changing. Further, the OLT may send the carrying operating parameter to the ONU by determining whether the intermediate frequency signal frequency value obtained by monitoring the change of the ac power value is within the range of the intermediate frequency allowable valueThe parameter adjusting instruction enables the intermediate frequency signal received by the OLT after the ONU adjusts the signal transmission parameter to meet the performance requirement of the coherent receiver.

As an example, for a photodetector with a 3-dB bandwidth of the OLT coherent receiver bandwidth (BW _ pd), when the AC power value P is greater_ACWhen the frequency value is half of the maximum AC power value, the frequency value of the corresponding intermediate frequency signal is + -BW _ pd, when the AC power value P is_ACThe frequency value of the corresponding intermediate frequency signal is near the frequency 0 when the value is the maximum alternating current power value.

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

And S140, monitoring the alternating current power value of the photocurrent signal output by the coherent receiver after the photoelectric detection is carried out on the intermediate frequency signal 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. 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. And S142, calculating an alternating current power value point corresponding to the frequency value in the intermediate frequency allowable value range according to the first corresponding relation and the frequency value in the intermediate frequency allowable value range. S143, determining the 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 the transmitter according to the carried working parameters; wherein, the intermediate frequency allowable value range is a frequency value range of the 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 corresponding relationship may be expressed as a curve of the ac power value with the change of the intermediate frequency value. In step S142, the intermediate frequency allowable value determined based on the type of the coherent receiver may specifically include: according to information such as modulation format, modulation rate, coherent receiver type, photoelectric detector bandwidth of an optical signal in an optical network system, an empirical value of an intermediate frequency allowable value meeting performance requirements of a coherent receiver is obtained in advance, and the empirical value is used as the intermediate frequency allowable value of the coherent receiver.

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

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

In one embodiment, the OLT may store a table of correspondence between receiver types and empirical values of the if allowable values, and the OLT reads the if 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, which may be implemented by the OLT and the ONU monitoring the uplink message carrying the working parameter (e.g., time value) sent by the ONU at the same time.

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

In the embodiment of the invention, after receiving the downlink message at the registration activation stage, the ONU performs wavelength tuning of the optical signal within a preset uplink wavelength range. Specifically, the wavelength tuning may be performed first in a first tuning direction, and when tuning to a wavelength endpoint value in the first tuning direction, the wavelength tuning may be performed in a second tuning direction, that is, the opposite direction of the first tuning direction.

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

Taking the first tuning direction as an example of tuning from the upper limit value of the upstream wavelength range to the lower limit value of the upstream wavelength range, in an embodiment, after receiving the downstream stream at the registration activation stage, the ONU performs wavelength tuning in the first tuning direction within the upstream wavelength range according to the first time interval Δ T1, records the wavelength tuning time point n Δ T1 corresponding to each wavelength tuning, and continues to perform wavelength tuning in the second tuning direction according to the specified time interval Δ T1 when the ONU receives the lower limit value of the wavelength within the upstream wavelength range.

And after the OLT sends the registration downstream message, monitoring and recording the detected alternating current power value according to a second time interval delta T2, and after the alternating current power value is detected, starting to record a power detection time point m delta T2 corresponding to each power monitoring to obtain a variation curve of the alternating current power value along with m delta T2.

As shown in fig. 4, for simplicity of description, a frequency value of an intermediate frequency signal obtained by mixing an optical signal emitted after the OLT detects that the ONU performs wavelength tuning with an intrinsic optical signal may be referred to as an intermediate frequency tuning value, where Δ T1 ═ Δ T2 ═ Δ T. And assuming that a time required for the ONU to adjust from the upper limit value to the lower limit value of the wavelength in the upstream wavelength range in the first adjustment direction is T, and assuming that a 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_rΔ T2 and n_rΔ T1 may take a corresponding plurality of sets of values. As shown in fig. 4, at a wavelength tuning time point n with the ONU_r1Corresponding to the optical signal emitted after the wavelength tuning of the delta T1, the time point when the OLT detects the AC power value is m_r1Δ T2; with ONU at wavelength tuning time point n_r2Corresponding to the optical signal emitted after the wavelength tuning of the delta T1, the time point when the OLT detects the AC power value is m_r2ΔT2。

In one embodiment, the wavelength tuning time point n is determined from the wavelength tuning time point n Δ T1 and the power detection time point m Δ T2_rΔ T1 and power detection time point m_rThe correspondence relationship of Δ T2 can be expressed as the following expression (8):

n_rΔT1-T＝m_rΔT2-(T′+(m₀ΔT2-T′)/2) (8)

in the above expression (8), m₀Δ T2 is a time value corresponding to when the OLT detects ac power within a time range in which the ONU continues wavelength tuning from the wavelength lower limit value in the second adjustment direction at predetermined time intervals to the wavelength upper limit value.

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 intermediate frequency signal frequency value; calculating to obtain a corresponding monitoring time point according to a second corresponding relation between the alternating current power value and the time and the corresponding alternating current power value; and determining the 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 by the expression (8).

In an embodiment, the step of determining the working parameter corresponding to the ac power value point in step S143 may specifically include S1431 to S1435.

Step S1431, an uplink message sent by the ONU after the signal transmission parameter adjustment is monitored, where the uplink message carries the parameter adjusting time and the working parameter used in the parameter adjusting time.

Step S1432, a second corresponding relationship between the ac power value and the monitoring time is determined according to the monitored ac power value and the corresponding monitoring time.

Step S1433, calculating the monitoring time corresponding to the ac power value by using the ac power value point corresponding to the frequency value within the range of the intermediate frequency allowable value and the second corresponding relationship, and obtaining a calculated value of the monitoring time.

Step S1434, determining the parameter adjusting time corresponding to the monitoring time calculation value to obtain a parameter adjusting time calculation value corresponding to the alternating current power value.

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

In one embodiment, the signal emission parameter may be adjusted from a first specified time point according to a first time interval of the parameter adjusting time, and the ac power value of the output photocurrent signal after the photoelectric detection of the coherent receiver may be monitored from a second specified time point according to a second time interval of the monitoring time, so as to determine a corresponding relationship between the monitoring time and the parameter adjusting time.

Illustratively, when the first specified time point is that the ONU responds to the received downlink message and adjusts the parameter adjusting time of the signal transmission parameter for the first time, the second specified time point is that after the OLT sends the downlink message, the ac power value of the first photocurrent signal is output after the coherent receiver is monitored to perform photoelectric detection.

Illustratively, the first specified time point is a parameter adjusting time when the ONU adjusts the signal transmission parameter in the opposite wavelength adjusting 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 is performed in the opposite wavelength adjusting direction.

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

Step S1435, the parameter adjusting time is the working parameter used when the parameter adjusting time is the calculated value of the parameter adjusting time, and the working parameter is used as the working parameter corresponding to the alternating current power value.

According to the coherent reception method of the embodiment of the invention, when the OLT monitors the wavelength tuning and working parameter messages reported by the ONU, the received messages need to be subjected to complete signal demodulation and frame analysis, and the processing time is long. Therefore, the emission parameters of the optical signals in the ONU are adjusted based on the monitored alternating current power value of the photocurrent after the detection of the intermediate frequency signal by the photoelectric detector in the OLT, signal demodulation and frame analysis are not required to be carried out in the OLT, and the data processing amount and the processing time of the OLT are further reduced.

In one embodiment, the ONU is the first ONU online in the optical distribution network, and the optical distribution network is located between the OLT and the ONU; the method further comprises the following steps: and carrying working parameters of the alternating current power value points corresponding to the intermediate frequency allowable value range in the registration activation downlink messages sent to other ONUs 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 value in the intermediate frequency allowable value range; and in the intermediate frequency allowable value range, the OLT monitors an alternating current power value when the first online ONU registers and activates the stage for wavelength tuning, acquires an intermediate frequency value corresponding to the monitored alternating current power value, and acquires a frequency value range of the intermediate frequency signal meeting the performance requirement of a coherent receiver in the OLT in the process of monitoring wavelength tuning.

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

And the OLT carries the intermediate frequency allowable value in a downstream message sent subsequently so that the subsequent ONU acquires the intermediate frequency allowable value. If the subsequent OLT receives that the optical parameter information of the uplink signal carried in the downlink message is the wavelength value of the intrinsic optical signal or the frequency value of the intrinsic optical signal, the subsequent OLT may calculate the adjustment direction of the transmission parameter and the adjustment value of the transmission parameter according to the intermediate frequency allowed value and the optical parameter information of the uplink signal, so as to adjust the signal transmission parameter in the ONU, thereby reducing the time for online calibration of the subsequent ONU and improving the calibration efficiency of the transmission parameter.

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

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

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

Step S150, in response to detecting that the wavelength of the optical signal drifts and the drift range is within the preset wavelength drift threshold range, sending a wavelength fine tuning instruction 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 ONU is monitored to have wavelength drift, the wavelength of the optical signal transmitted by the OLT is finely adjusted, so as to improve the signal quality of the upstream optical signal.

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

Step S160, when monitoring that the ONU is in an unregistered state after being online, judging that the ONU needs to adjust the transmission parameter of the optical signal; and if the uplink messages from the plurality of ONUs are received in the adjacent time period, selecting the ONU which is allowed to be registered according to the parameter adjustment times carried in the uplink message of each ONU.

In one embodiment, the ONU with the most parameter adjustments may be regarded 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 the embodiment of the present invention, the signal adjusting method may further include steps S170 and S171.

Step S170, if the frequency value of the monitored intermediate frequency signal is within the range of the intermediate frequency allowable value 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 that the uplink message cannot be correctly analyzed and that the error rate is higher than the error rate threshold, it is determined that the ONU has an uplink data collision. Step S171, notifying the ONU to maintain the working parameter corresponding to the ac power value point, and performing back-off for the uplink data collision.

In this embodiment, the OLT determines whether an ONU conflict occurs according to the monitored ac power value and the upstream message frame analysis result, and if it is determined that the ONU conflict, notifies the ONU to maintain the operating parameter corresponding to the intermediate frequency allowed value and perform back-off processing. As an example, the detection mechanism for the OLT to detect ONU collisions includes, but is not limited to: the alternating current power value is monitored to be within the intermediate frequency allowable value range, but frame analysis cannot be completed correctly or the error rate is high.

In the coherent receiving method described above with reference to fig. 1 to 4, the OLT may trigger the ONU to perform transmission parameter adjustment and online calibration by sending a downlink message, and the intermediate frequency signal frequency corresponding to the adjusted signal light is within the intermediate frequency allowable value range, thereby solving the problem that the operating 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.

Fig. 5 is a flow chart of a signal processing method according to another embodiment of the present invention. As shown in fig. 5, in an embodiment, the signal processing method may be used for an optical network unit ONU, and includes: s210, responding to the received downlink message from the OLT, and adjusting the signal transmission parameters of the optical signals; s220, sending the optical signal to the OLT according to the adjusted signal emission parameter, so that the optical signal and the intrinsic optical signal are subjected to coherent mixing processing to obtain an intermediate frequency signal of which the frequency value is within the range of the intermediate frequency allowable value.

According to the signal processing method provided by the embodiment of the invention, the OLT responds to the received downlink message from the OLT and adjusts the transmission parameters of the optical signal, so that the frequency value of the obtained intermediate frequency signal is within the range of the intermediate frequency allowable value after the transmitted optical signal and the intrinsic optical signal are subjected to coherent mixing processing in the OLT, and the influence of uncertain working wavelength of the ONU in the uplink direction in an optical network system on the communication between the ONU and the OLT 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 a signal transmission parameter according to the uplink signal optical parameter information carried in the downlink message, where the uplink signal optical parameter information is used to indicate a signal transmission parameter capable of obtaining an intermediate frequency signal whose frequency value is within the intermediate frequency allowable value range.

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

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

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

Step S212, obtaining the adjustable range of the transmission parameter from the uplink signal optical parameter information carried by the downlink message, and adjusting the signal transmission parameter within the adjustable range of the transmission parameter. Step S213, sending an uplink message to the OLT by using the adjusted signal transmission parameter. Step S214, in response to receiving the feedback message of the uplink message, using the signal transmission parameter corresponding to the uplink message as the signal transmission parameter at the normal working stage of the ONU.

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 transmitted by the ONU using the adjusted signal transmission parameter and correctly analyzes the upstream message, the OLT transmits a feedback message of the upstream message to the ONU.

In one embodiment, the interval duration of two adjacent adjustments is longer than the message round-trip duration 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.

In this embodiment, the uplink message may or may not carry the 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, it is necessary to set the interval duration between two adjacent adjustments to be greater than the message round-trip duration 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 duration of two adjacent adjustments is longer than the message round-trip duration 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.

In this embodiment, when the transmission parameter adjustable range adjusts the signal transmission parameter, if the uplink message carries the 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, thereby improving the parameter adjustment efficiency of the ONU.

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

Step S215, adjusting the signal transmission parameter multiple times within the preset uplink wavelength range. Step S216, transmitting an uplink message to the OLT by using the signal light after each adjustment, where the uplink message carries 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 parameter and/or the transmitter operating parameter of the ONU in the normal operating stage according to the adjustment information carried in the uplink message, where the feedback message is used to indicate that the uplink message is correctly parsed.

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

In one embodiment, the adjustment information of the signal transmission parameters 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 transmission parameters, tuning times serial numbers, transmission parameter adjusting directions, transmission parameter adjusting values, parameter adjusting time and transmitter working parameters.

In one embodiment, the signal processing method may further include: s230, sending registration information to the OLT in response to receiving a registration request sent by the OLT according to the adjusted signal emission parameters; s231, after the OLT is successfully registered, storing the adjusted signal transmission parameters and the transmitter working parameters in the ONU; and S232, setting the signal emission parameters under the ONU working state and the transmitter working parameters under the ONU working state according to the stored signal emission 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, the OLT receives the adjusted optical signal, and if the frequency value of the intermediate frequency signal obtained by performing coherent mixing processing on the adjusted optical signal and the intrinsic optical signal in the OLT is within the range of the intermediate frequency allowable value, the OLT may start a registration process for the ONU. After the ONU completes the registration process, the adjusted wavelength information and the operating parameters of the ONU optical module transmitter may be stored, and the wavelength information and the operating parameters of the ONU optical module transmitter may be used for setting the wavelength at the normal operating stage of the ONU and setting the operating parameters of the ONU optical module transmitter at the normal operating stage.

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

In one embodiment, the signal processing method may further include: and performing wavelength fine adjustment on the optical signal transmitted by the OLT in response to receiving a 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 adjusting the signal transmission parameter regularly in 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, and the signal transmission parameters are 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 OLT, the ONU adjusts the transmission parameters of the optical signal 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 work wavelength of the ONU in the uplink direction and ONU wavelength drift 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 sent 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 magnitude of the injection current, the magnitude of the cavity length and the like. The corresponding relation between the parameter and the wavelength value of the optical signal finally emitted by the ONU optical module can be stored in the ONU optical module.

Fig. 6 shows a schematic structural diagram 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 media 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 functionally identical 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 alternating current power monitoring module 315.

The intrinsic light source input module 311 is configured to input an intrinsic light source to the mixer; the mixer 312 is configured to perform mixing processing on the received signal light and the intrinsic light source to obtain an intermediate frequency signal; the photoelectric detector 313 is used for detecting the intermediate frequency signal output by the mixer, and performing photoelectric processing on the intermediate frequency signal to obtain a photocurrent signal; the alternating current power monitoring module 315 is configured to monitor an alternating current power value of the optical current signal; the signal processing module 314 may perform signal demodulation, clock recovery, data analysis, and the like on the uplink feedback information transmitted by the optical signal; the media access controller 320 may be configured to provide error detection, CRC check, uplink signal frame parsing, and determine whether the adjusted ONU signal satisfies a coherent reception condition; obtaining an alternating current power value change curve according to an alternating current power value provided by the alternating current power monitoring module; storing a range of coherent allowable frequency values for the coherent receiver; analyzing an uplink signal sent by the ONU to adjust working parameters; and a downlink signal framing step of sending a downlink message to an Optical Network Unit (ONU) for triggering the ONU to adjust signal transmission parameters, inform ONU back-off and other message interaction control functions between the OLT and the ONU.

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

Continuing with reference to figure 6, in one embodiment, the optical line terminal may include a media access controller module 320 and a signal receiving module 310.

The media access controller module is used for sending a downlink message to the ONU, and the downlink message is used for triggering the ONU to adjust the 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 value range.

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

In one embodiment, the media access controller 320 may include: an uplink parameter determining unit, configured to determine uplink 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; and the downlink message sending unit is also used for sending the downlink message carrying the optical parameter information of the uplink signal.

In this embodiment, the range of the intermediate frequency allowable value is a range of frequency values 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. The performance requirements of the coherent receiver are met, including but not limited to the fact that the coherent receiver meets the sensitivity requirements of the receiver, for example, the power value of the received optical signal under a certain error code condition is greater than or equal to a preset power threshold, and after signal demodulation, clock recovery and data analysis are performed on the received optical signal, CRC check is correct, and message is correct and analyzed.

In an embodiment, the uplink parameter determining unit may be specifically configured to: using a frequency channel value or a wavelength channel value corresponding to the frequency value of the intrinsic optical signal as optical parameter information of the uplink signal; or, taking a target transmitting parameter value corresponding to the frequency value of any intermediate frequency signal within the intermediate frequency allowable value range as the optical parameter information of the uplink signal; 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; 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.

In one embodiment, the media 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; and the adjustment information carrying unit is used for carrying the adjustment information in the feedback message if the uplink message carries the adjustment information of the ONU adjustment signal transmission parameters.

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

In one embodiment, the media access controller 320 in the optical line terminal may further include: the alternating current power value monitoring unit is used for monitoring the alternating current power value output by the alternating current power monitoring module 315 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; the first relation determining unit is used for 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; the alternating current power calculation unit is used for calculating an alternating current power value point corresponding to the frequency value within the intermediate frequency allowable value range according to the first corresponding relation and the frequency value within the intermediate frequency allowable value range; the medium access controller 320 may be further configured to determine a working parameter corresponding to the ac power value point, and send a parameter adjusting instruction carrying the working parameter to the ONU, so that the ONU adjusts the working parameter of the transmitter according to the carried working parameter; wherein, the intermediate frequency allowable value range is a frequency value range of the 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, the optical line terminal may include: the uplink message monitoring unit is used for monitoring an uplink message sent by the ONU after the signal transmission parameter is adjusted, and the uplink message carries 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 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 and the working parameters used by the parameter adjusting time point according to the uplink message monitored when the monitoring time is the monitoring time calculation value.

In one embodiment, the ONU is the first ONU online in the optical distribution network, and the optical distribution network is located between the OLT and the ONU; and the information carrying module can also be used for carrying the working parameters corresponding to the alternating current power value points in the retransmission 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 value in the intermediate frequency allowable value range; and in the intermediate frequency allowable value range, the OLT monitors an alternating current power value when the first online ONU registers and activates the stage for wavelength tuning, acquires an intermediate frequency value corresponding to the monitored alternating current power value, and acquires a frequency value range of the intermediate frequency signal meeting the performance requirement of a coherent receiver in the OLT in the process of monitoring wavelength tuning.

In one embodiment, the medium access controller 320 may further include: the collision monitoring unit is used for judging that the ONU has uplink data collision if the monitored intermediate frequency signal is within the range of the intermediate frequency allowable value 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 uplink message cannot be correctly analyzed 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 AC power value point and back off the uplink data collision.

In some embodiments, the Media Access Controller is different from a Media Access Controller (MAC) chip in the PON system. That is, the MAC implements the functions described in the above embodiments according to corresponding software functional modules, which are not necessarily solidified in the MAC chip. Moreover, since there are differences between media access controllers in different PON devices, it is not suitable for being fixed on a MAC chip.

According to the optical line terminal provided by the embodiment of the invention, after the media access controller sends the downlink message to the ONU, the ONU is triggered to adjust the transmission parameter 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 work wavelength of the ONU in the uplink direction and ONU wavelength drift in an optical network system are solved.

It is to be understood that the invention is not limited to the particular arrangements and instrumentality described in the above embodiments and shown in the drawings. For convenience and brevity of description, detailed description of a known method is omitted here, and for a specific working process of the optical line terminal according to the embodiment of the present invention, reference may be made to a corresponding working process of the OLT in the coherent receiving method embodiment described above in combination with the embodiment, which is not described herein again.

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 an embodiment, an optical network unit ONU may include: a signal transmitting module 410, a signal receiving module 420 and a media access controller 430.

The transmitting module 410 may include a transmitting parameter adjusting module 411 and a signal optical transmitter 412. Specifically, the transmission parameter adjusting and controlling module 411 is configured to adjust a signal transmission parameter of the optical signal in response to receiving a downlink message from the OLT; and the signal optical transmitter 412 is configured to transmit an optical signal to the OLT according to the adjusted signal transmission parameter, so that the optical signal and the intrinsic optical signal are subjected to coherent mixing processing to obtain an intermediate frequency signal with a frequency value within an intermediate frequency allowable value range.

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

The media access controller 430 may be configured to perform frame analysis on the downlink signal sent by the OLT, and complete framing and sending of the uplink signal of the ONU.

In an embodiment, the transmission parameter adjusting module 411 may be specifically configured to: and adjusting the signal transmitting parameters according to the uplink signal optical parameter information carried in the downlink message, wherein the uplink signal optical parameter information is used for indicating the signal transmitting parameters of the intermediate frequency signals of which the frequency values are within the range of the intermediate frequency allowable value.

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

The parameter adjusting range acquiring unit is configured to acquire an adjustable range of a transmission parameter from uplink signal optical parameter information carried in a downlink message, and output the adjustable range of the transmission parameter to the transmission parameter adjusting module 411; the transmission parameter adjusting and controlling module 411 is further configured to adjust a signal transmission parameter within an adjustable range of the transmission 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, in response to receiving the feedback message of the uplink message, 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 that the OLT sends to the ONU when receiving the upstream message sent by the signal optical transmitter 412 and correctly parsing the upstream message. That is, the feedback message of the upstream message is used to instruct the OLT to receive and correctly parse the upstream message.

In an embodiment, the transmission parameter adjusting module 411 may further include:

and the parameter adjusting unit is used for adjusting the signal emission parameters for multiple times within a preset uplink wavelength range.

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

And the transmission parameter determining unit is further configured to determine, in response to receiving a feedback message of the uplink message, a signal transmission 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, 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 transmission parameters, tuning times serial numbers, transmission parameter adjusting directions, transmission parameter adjusting values, parameter adjusting time and transmitter working parameters.

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 parameters; the media access controller 430 may further include a parameter storage unit, where the parameter storage unit is configured to store the adjusted signal transmission parameter and the transmitter operating parameter in the ONU after the OLT is successfully registered with the OLT according to the registration information; the parameter setting unit is used for setting the signal emission parameters of the ONU in the normal working stage and the transmitter working parameters of the ONU in the normal working stage by using the stored signal emission parameters and the stored transmitter working parameters.

According to the optical network unit disclosed by the embodiment of the invention, the transmitting parameters of the optical signals are adjusted and calibrated on line in response to the received downlink message sent by the OLT, so that the problem that the working wavelength of the ONU in the uplink direction in an optical network system is uncertain and exceeds the intermediate frequency receiving range of the OLT coherent receiver is solved.

It is to be understood that the invention is not limited to the particular arrangements and instrumentality described in the above embodiments and shown in the drawings. For convenience and brevity of description, detailed description of a known method is omitted here, and for a specific working process of the optical network unit in the embodiment of the present invention, reference may be made to a corresponding working process of the optical network unit in the signal processing method embodiment 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 an embodiment, an optical network system may comprise an optical line termination OLT510 and an optical network unit ONU 520.

The OLT is used for sending a downlink message to the 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 parameter of the optical signal and sending the optical signal to the OLT according to the adjusted signal transmission parameter; the OLT is further configured to perform coherent mixing processing on the received 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 the optical network system of the embodiment of the invention, the OLT can trigger the ONU to carry out emission parameter adjustment and online calibration 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 according to the embodiment of the present invention may refer to the corresponding working process of the OLT in the coherent reception method embodiment described in the foregoing embodiment; as well as the specific working process of the ONU according to the embodiments of the present invention, reference may be made to the corresponding working process of the ONU according to the embodiment of the signal processing method described in the foregoing embodiments.

It is to be understood that the invention is not limited to the particular arrangements and instrumentality described in the above embodiments and shown in the drawings. For convenience and brevity of description, detailed description of a known method is omitted here, and for the specific working processes of the system, the module and the unit described above, reference may be made to corresponding processes in the foregoing method embodiments, which are not described herein again.

FIG. 9 is a block diagram illustrating an exemplary hardware architecture capable of implementing a computing device according to embodiments of the present invention. As shown in fig. 9, 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 processing unit 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; central processor 903 processes input information based on computer-executable instructions stored in memory 904 to generate output information, stores the output information temporarily or permanently in memory 904, and then transmits the output information to output device 906 via output interface 905; output device 906 outputs the output information external to 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 reception system that may include: a memory configured to store a program; a processor configured to execute the program stored in the memory to perform the coherent reception method described in the above embodiments.

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; a processor configured to execute the program stored in the memory to perform the signal processing method described in the above embodiments.

According to an embodiment of the invention, the process described above with reference to the flow chart may be implemented as a computer software program. 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 illustrated in the flow chart. In such an embodiment, the computer program may be downloaded and installed from a network, and/or installed from a removable storage medium.

It will be understood by those of ordinary skill in the art that all or some of the steps of the methods, systems, functional modules/units in the devices disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between 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 by several physical components in cooperation. 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 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 is well known to those of ordinary skill 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 accessed by a computer. In addition, 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 as known to those skilled in the art.

It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.

Claims

1. A coherent receiving method is used for an Optical Line Terminal (OLT), and comprises the following steps:

sending 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 the intrinsic optical signal adopted by the OLT to obtain an intermediate frequency signal of which the frequency value is within the range of an intermediate frequency allowable value.

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

determining 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;

sending a downlink message carrying the optical parameter information of the uplink signal;

wherein the intermediate frequency allowable value range is a frequency value range of the 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 uplink signal optical parameter information from at least one of the intermediate frequency allowed value range and the frequency value of the intrinsic optical signal comprises:

using a frequency channel value or a wavelength channel value corresponding to the frequency value of the intrinsic optical signal as the optical parameter information of the uplink signal; alternatively, the first and second electrodes may be,

taking a target transmitting parameter value corresponding to the frequency value of any intermediate frequency signal in the range of the intermediate frequency allowable value as the optical parameter information of the uplink signal; alternatively, the first and second electrodes may be,

calculating a transmitting parameter adjusting direction and a transmitting parameter adjusting value according to the frequency value of the intrinsic optical signal and the frequency value of the intermediate frequency signal, and using the calculated transmitting parameter adjusting direction and transmitting parameter adjusting value as the uplink signal optical parameter information;

or, determining an adjustable range of a transmission parameter according to the frequency value of the intrinsic optical signal and the bandwidth of the coherent receiver of the OLT, and using 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 an uplink message received 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 uplink messages that are correctly parsed within a specified time period is greater than 1, the sending the feedback message for the uplink message further comprises:

sending the feedback message aiming at any uplink message which is correctly analyzed; alternatively, the first and second electrodes may be,

sending the feedback message aiming at selecting the uplink message which is correctly analyzed and has the lowest error rate; alternatively, the first and second electrodes may be,

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

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

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

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 within the range of the intermediate frequency allowable value, calculating an alternating current power value point corresponding to the frequency value within the range of the intermediate frequency allowable value;

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 the transmitter according to the carried working parameters;

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

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

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;

calculating the monitoring time corresponding to the alternating current power value by using the alternating current power value point corresponding to the frequency value within 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 calculation value to obtain a parameter adjusting time calculation value corresponding to the alternating current power value;

and taking the working parameters used when the parameter adjusting time is the calculated value of the parameter adjusting time as the working parameters corresponding to the alternating current power value.

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 following steps:

working parameters of alternating current power value points corresponding to the intermediate frequency allowable value range are carried in registration activation downlink messages sent to other ONUs 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 value in the intermediate frequency allowable value range;

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

9. The method of claim 6, further comprising:

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

and informing the ONU to keep the working parameters corresponding to the alternating current power value and carrying out backoff on the uplink data collision.

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

responding to a received downlink message from an Optical Line Terminal (OLT), and adjusting a signal transmission parameter of an optical signal;

and sending an optical signal to the OLT according to the adjusted signal emission parameter so as to obtain an intermediate frequency signal with a frequency value within an intermediate frequency allowable value range after the optical signal and the intrinsic optical signal are subjected to coherent mixing processing.

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

adjusting signal emission parameters according to uplink signal optical parameter information carried in the downlink message, wherein the uplink signal optical parameter information is used for indicating signal emission parameters of intermediate frequency signals of which the frequency values are within the range of the intermediate frequency allowable value;

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

acquiring an adjustable range of a transmission parameter from uplink signal optical parameter information carried by the downlink message, and adjusting a signal transmission parameter within the adjustable range of the transmission parameter;

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

responding to the received feedback message of the uplink message, and taking the signal transmission parameter corresponding to the uplink message as the signal transmission parameter of the ONU in the normal working state;

the interval duration of the two adjacent times of adjustment is longer than the message round-trip duration 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 a coherent receiver in the OLT.

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

adjusting signal emission parameters for multiple times within a preset uplink wavelength range;

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

and responding to a feedback message of the received uplink message, and determining a signal transmission parameter and/or a transmitter working parameter of the ONU in a normal working state according to 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 parameters comprises any one of the following items of information corresponding to each of the adjustments:

parameter setting of signal transmission parameters, tuning times serial numbers, transmission parameter adjusting directions, transmission parameter adjusting values, parameter adjusting time and transmitter working parameters.

15. The method of claim 10, further comprising:

sending registration information to the OLT in response to receiving a registration request sent by the OLT according to the adjusted signal emission parameters;

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

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

16. An optical line terminal comprising:

the media access controller module is used for sending a downlink message to an 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 responding to the received adjusted optical signal and carrying out coherent mixing processing on the optical signal and the intrinsic optical signal to obtain an intermediate frequency signal of which the frequency value is within the range of an intermediate frequency allowable value.

17. An optical network unit comprising:

the transmitting parameter regulating and controlling module is used for responding to the received downlink message from the OLT and regulating the signal transmitting parameters of the optical signals;

and the signal transmitting module is used for transmitting an optical signal to the OLT according to the adjusted signal transmitting parameter so as to obtain an intermediate frequency signal of which the frequency value is within the range of an intermediate frequency allowable value after the optical signal and the intrinsic optical signal are subjected to coherent mixing processing.

18. An optical network system comprising an optical line terminal, OLT, and optical network units, ONU,

the OLT is used for sending a downlink message to an 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 parameter of the optical signal and sending the optical signal to the OLT according to the adjusted signal transmission parameter;

and the OLT is further 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 of which the frequency value is within an intermediate frequency allowable value range.

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 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.