WO2021218181A1 - Onu, olt, optical communication system, and data transmission method - Google Patents

Abstract

An optical network unit (ONU), an optical line terminal (OLT), an optical communication system, and a data transmission method, for use in solving the problem in the prior art of long delays of data sent by ONUs. The ONU can be applied to passive optical networks, etc. The ONU may comprise a coding module and an electro-optical conversion module; the coding module is configured to perform orthogonal coding on data to be sent to obtain an electrical signal, and transmit the electrical signal to the electro-optical conversion module; the electro-optical conversion module is configured to convert the electrical signal into an optical signal, and send the optical signal to the OLT over an optical distribution network (ODN). When multiple ONUs need to send data, the electrical signals of the multiple ONUs do not interfere with each other, and data of the multiple ONUs can reach the OLT at the same time, thereby facilitating reducing the delay of data sent by the ONUs. That is, by means of orthogonal coding by coding modules, a logical point-to-point link is established between each ONU and the OLT, equivalently.

Description

An ONU, OLT, optical communication system and data transmission method

This application claims the priority of a Chinese patent application filed with the State Intellectual Property Office of China, the application number is 202010356197.8, and the invention title is "an ONU, OLT, optical communication system and data transmission method" on April 29, 2020, all of which The content is incorporated in this application by reference.

Technical field

This application relates to the field of communication technology, and in particular to an ONU, OLT, optical communication system and data transmission method.

Background technique

With the rapid development of broadband access technology, passive optical network (PON) systems are increasingly used in optical communication technologies. The PON system includes an optical line terminal (OLT) and multiple optical network units (ONUs), where the OLT communicates with multiple ONUs. In the transmission of uplink signals, each ONU can only send data in the time slot allocated to it, and the transmitter must be turned off during the rest of the time. If multiple ONUs transmit signals at the same time, it will cause interference between signals.

In order to ensure the normal operation of a time division multiplexing (TDM) PON, the time slot for each ONU to send data must be strictly allocated to avoid interference between signals. Moreover, the data of ONUs that are different in time do not overlap each other from front to back, and there is a certain blank gap in time between each data to further ensure that the time of sending data does not overlap. In this way, although the crosstalk between the signals can be avoided to a certain extent, the data of the ONU that sends data later will arrive at the OLT later than the data of the ONU that is in the front, especially when the number of ONUs in the front is large. Later, the delay of ONU sending data will be greater.

Summary of the invention

This application provides an ONU, an OLT, an optical communication system, and a data transmission method, which are used to reduce the time delay of data sent by the ONU.

In the first aspect, the present application provides an ONU that includes an encoding module and an electro-optical conversion module; the encoding module is used to orthogonally encode data to be sent to obtain an electrical signal, and transmit the electrical signal to the electro-optical conversion module; The conversion module is used to convert the received electrical signal into an optical signal, and send the optical signal to the OLT through an optical distribution network (optical distribution network, ODN).

Based on this solution, the encoding module performs orthogonal encoding on the data to be sent by the ONU to obtain an electrical signal. Because of the orthogonal encoding, the electrical signals obtained by different ONUs are different from each other and orthogonal to each other. If there are multiple ONUs that need to send data, the electrical signals of the multiple ONUs do not interfere with each other, and multiple ONUs can transmit optical signals at the same time, that is, the data of multiple ONUs can overlap in time. In this way, data from multiple ONUs can reach the OLT at the same time, thereby helping to reduce the delay of data sent by the ONU. Moreover, there is no need to reserve blank time slots in time between ONUs, which can further reduce the time delay of data sent by ONUs. In other words, through the orthogonality coding of the coding module, it is equivalent to establishing a logical point-to-point link between each ONU and OLT (that is, ONU and OLT are independent point-to-point transmission channels). Interfere with each other.

In a possible implementation, the encoding module is a frequency division multiplexing access (FDMA) encoder; the encoding module is specifically used to determine the frequency band corresponding to the ONU, and to multiply the data with the corresponding frequency band. Get electrical signals.

Through the above-mentioned FDMA encoder in the ONU, the orthogonality of the electrical signals of different ONUs in the frequency domain can be realized, thereby ensuring that the data transmitted by multiple ONUs at the same time does not interfere with each other.

Further, optionally, the encoding module is further configured to receive first configuration information from the OLT, where the first configuration information includes the frequency band corresponding to the ONU.

By receiving the first configuration information by the OLT, the frequency band corresponding to the ONU can be quickly determined, thereby helping to improve the coding efficiency of the coding module.

In a possible implementation, the encoding module is a code division multiple access (CDMA) encoder; the encoding module is specifically used to determine the codeword corresponding to the ONU, and to perform multiplication operations on the data and the corresponding codeword, Get electrical signals.

Through the above-mentioned CDMA encoder in the ONU, the orthogonality of the electrical signals of different ONUs in the time domain can be realized, thereby ensuring that the data transmitted by multiple ONUs at the same time does not interfere with each other.

Further, optionally, the encoding module is further configured to receive second configuration information from the OLT, where the second configuration information includes a codeword corresponding to the ONU.

By receiving the second configuration information by the OLT, the codeword corresponding to the ONU can be quickly determined, thereby helping to improve the coding efficiency of the coding module.

In a possible implementation, the electro-optical conversion module is specifically configured to receive the first injection light emitted by the injection light source from the OLT, generate a first optical carrier based on the first injected light, and modulate the electrical signal onto the first optical carrier , The optical signal is obtained, and the wavelength of the first optical carrier is equal to the wavelength of the first injected light.

The first injection light emitted by the injection light source from the OLT received by the ONU can make the wavelength of the optical signal emitted by the ONU controllable, thereby helping to reduce the complexity of data recovery by the OLT. Further, the wavelength of the first injected light received by each ONU is the same, which can save wavelength resources, thereby helping to reduce the cost of integrated ONU.

In a possible implementation manner, the electro-optical conversion module is specifically configured to receive N second injection lights emitted by the injection light source from the OLT, generate a second optical carrier based on the N second injection lights, and modulate the electrical signal to the first The optical signal is obtained on the second optical carrier, the wavelength of the second optical carrier is the same as the wavelength of the second injected light among the N second injected lights, and N is an integer greater than 1.

Through the above-mentioned ONU, the electro-optical conversion module receives the N second injected lights emitted by the injection light source from the OLT, which can make the wavelength of the optical signal emitted by the ONU controllable, thereby helping to reduce the complexity of data recovery by the OLT, compared to The first injected light of a single wavelength and the second injected light of N different wavelengths can further reduce the complexity of data recovery by the OLT.

In a second aspect, the present application provides an OLT, which includes a photoelectric conversion module and a decoding module. The photoelectric conversion module is used to receive the superimposed optical signal through the ODN, convert the superimposed optical signal into a superimposed electrical signal, and transmit the superimposed electrical signal to the decoding module. The superimposed optical signal is obtained by superimposing M optical signals from M ONUs. The signal includes M mutually orthogonal electrical signals, M electrical signals correspond to M optical signals one-to-one, M ONUs correspond to M optical signals one-to-one, and M is an integer greater than 1; the decoding module is used to superimpose electrical signals. The signal is decoded to obtain the data sent by each ONU among the M ONUs.

Based on the above solution, the OLT receives the superimposed optical signal, converts the superimposed optical signal into a superimposed electrical signal through the photoelectric conversion module, and decodes the superimposed electrical signal by the decoding module to simultaneously obtain M data from M ONUs. In this way, it helps to reduce the time delay of the data sent by the M ONUs. Furthermore, the superimposed electrical signals are M mutually orthogonal electrical signals, which do not interfere with each other, so that independent and non-interfering data sent by each ONU can be obtained.

In a possible implementation, the decoding module is an FDMA decoder, and the FDMA decoder may include K filters. The frequency bands allowed by each of the K filters are different, and K is a positive integer; K filters Each filter in is used to allow the electrical signal of the corresponding frequency band in the superimposed electrical signal to pass. One ONU corresponds to one frequency band, and the frequency bands corresponding to any two ONUs do not overlap each other.

Through the above-mentioned FDMA decoder in the OLT, the data sent by each of the M ONUs can be decoded. In a possible implementation, the decoding module is a CDMA decoder; the CDMA decoder is used to multiply and accumulate the codeword corresponding to each ONU in the M ONUs and the superimposed electrical signal to obtain the transmission of each ONU in the M ONUs. One ONU corresponds to one codeword, and any two codewords are orthogonal to each other.

Through the CDMA decoder in the OLT, the data sent by each of the M ONUs can be decoded.

In a possible implementation manner, the OLT may further include an injection light source; the injection light source is used to respectively emit the first injection light to each of the M ONUs; wherein the first injection light is used for the ONU to generate the first light Carrier, the first optical carrier is used to carry the electrical signal of the ONU, and the wavelength of the first optical carrier is the same as the wavelength of the first injected light.

Through the injection light source in the OLT, the first injection light of a single wavelength can be emitted to each ONU of the M ONUs, so that the wavelength of the optical signal emitted by the ONU can be equal to the wavelength of the first injection light, that is, the ONU can emit The wavelength of the optical signal is controllable, thereby helping to reduce the complexity of OLT restoring ONU data.

In a possible implementation, the OLT further includes an injection light source, and the injection light source is used to respectively emit N second injection lights to each of the M ONUs; wherein, the N second injection lights are used for ONU generation The second optical carrier. The second optical carrier is used to carry the electrical signal of the ONU. The wavelengths of the N second injected lights are different, and the wavelength of the second optical carrier is the same as the wavelength of one of the N second injected lights. , N is an integer greater than 1.

Through the above-mentioned injection light source in the OLT, N second injection lights can be emitted to each of the M ONUs, so that the ONU can select the second injection light of one wavelength from the N second injection lights, so that The wavelength of the optical signal emitted by the ONU is the same as the wavelength of the selected second injection light, so that the wavelength of the optical signal emitted by the ONU is controllable, thereby helping to reduce the complexity of restoring the data of the ONU by the OLT.

In a possible implementation, the photoelectric conversion module is a coherent receiver, which includes an intrinsic light source, an optical mixer, and a balanced detector; the intrinsic light source is used to emit intrinsic light to the optical mixer; The mixer is used to mix the received intrinsic light and superimposed light signals to obtain a mixed signal, and transmit the mixed signal to a balanced detector; the balanced detector is used to convert the mixed signal into a superimposed electrical signal, And transmit the superimposed electrical signal to the decoding module.

Through the above-mentioned coherent receiver in the OLT, the received superimposed optical signal can be converted into a superimposed electrical signal. Moreover, it helps to improve reception performance.

In a possible implementation, the photoelectric conversion module may include an avalanche photodiode (APD) and a trans-impedance amplifier (TIA); the APD is used to receive and superimpose optical signals. Converted to a superimposed current signal; TIA is used to convert a superimposed current signal into a superimposed voltage signal.

The APD and TIA in the above-mentioned OLT can convert the received superimposed optical signal into a superimposed electrical signal. Furthermore, the APD has a gain of 10 to 200 times, which can improve the sensitivity of receiving superimposed optical signals. Moreover, since the superimposed electrical signals are M different and mutually orthogonal electrical signals, the TIA does not require a burst TIA, that is, the TIA does not need to perform the function of fast magnification switching, and can directly reuse the existing technology. TIA in China, in this way, helps reduce the cost of integrated OLT.

In a possible implementation, the superimposed electrical signal includes superimposed analog electrical signals and superimposed digital electrical signals; the OLT also includes an analog-to-digital conversion module; the analog-to-digital conversion module is used to receive the superimposed analog electrical signal from the photoelectric conversion module, and The superimposed analog electrical signal is converted into a superimposed digital electrical signal, and the superimposed digital electrical signal is transmitted to the decoding module.

In a third aspect, the present application provides an optical communication system, which may include M ONUs in the first aspect or any one of the first aspects, an OLT in any one of the second or second aspects mentioned above, As well as ODN, the OLT communicates with each of the M ONUs through the ODN.

Based on the above optical communication system, the encoding module in the ONU performs orthogonal encoding on the data to be sent by the ONU to obtain electrical signals. Because of the orthogonal encoding, the electrical signals obtained by different ONUs are different from each other and orthogonal to each other. . If there are multiple ONUs that need to send data, the electrical signals of the multiple ONUs do not interfere with each other, and multiple ONUs can transmit optical signals to the OLT at the same time, that is, the data of multiple ONUs can overlap in time. In this way, data from multiple ONUs can reach the OLT at the same time, thereby helping to reduce the delay of data sent by the ONU. In other words, through the orthogonality coding of the coding module, it is equivalent to establishing a logical point-to-point link between each ONU and OLT (that is, ONU and OLT are independent point-to-point transmission channels). Interfere with each other. After the decoding module decodes the superimposed electrical signal, M data from M ONUs can be obtained at the same time.

In a possible implementation, the ODN includes a backbone fiber, an optical splitter, and M branch fibers. The M branch fibers correspond to the M ONUs one-to-one, and the splitter and each of the M ONUs pass through the corresponding branch fibers. Connected, the OLT and the optical splitter are connected through the backbone optical fiber, and M is an integer greater than 1; each ONU of the M ONUs is used to send optical signals to the optical splitter through the corresponding branch fiber; the optical splitter is used for the received M optical The signals are combined to obtain the superimposed optical signal, and the superimposed optical signal is sent to the OLT through the backbone fiber.

In a fourth aspect, the present application provides a data transmission method, which can be applied to the ONU of the first aspect or any one of the first aspects. The method may include performing orthogonal encoding on the data to be sent to obtain an electrical signal; converting the electrical signal into an optical signal, and sending the optical signal to the OLT through the ODN.

The following exemplarily shows two implementations of orthogonal encoding of the data to be sent.

Implementation method 1: Determine the frequency band corresponding to the ONU, and multiply the data with the corresponding frequency band to obtain an electrical signal. It should be understood that different ONUs correspond to different frequency bands, and the frequency bands corresponding to any two ONUs do not overlap.

Further, optionally, first configuration information from the OLT may be received, where the first configuration information includes the frequency band corresponding to the ONU.

Implementation mode 2: Determine the codeword corresponding to the ONU, and multiply the data with the corresponding codeword to obtain an electrical signal. It should be understood that different ONUs correspond to different codewords, and different codewords are orthogonal to each other.

Further, optionally, second configuration information from the OLT may be received, where the second configuration information includes a codeword corresponding to the ONU.

In a possible implementation manner, the first injection light emitted from the OLT may be received, the first optical carrier is generated according to the first injected light, and the electrical signal is modulated onto the first optical carrier to obtain the optical signal. The wavelength of the carrier is equal to the wavelength of the first injected light.

In another possible implementation manner, N second injected lights emitted from the OLT can be received, a second optical carrier is generated according to the N second injected lights, and the electrical signal is modulated onto the second optical carrier to obtain the light Signal, the wavelength of the second optical carrier is the same as the wavelength of one of the N second injected lights, and N is an integer greater than 1;

For the technical effects that can be achieved by any aspect of the foregoing fourth aspect, reference may be made to the description of the beneficial effects in the foregoing first aspect, and details are not repeated here.

In a fifth aspect, the present application provides a data transmission method, which can be applied to the OLT of any one of the above-mentioned second aspect or the second aspect. The method may include receiving superimposed optical signals through an optical distribution network ODN, and converting the superimposed optical signals into superimposed electrical signals. The superimposed optical signals are obtained by superimposing M optical signals from M optical network units ONUs, and the superimposed electrical signals include M Mutual orthogonal electrical signals, M electrical signals correspond to M optical signals one-to-one, M ONUs correspond to M optical signals one-to-one, M is an integer greater than 1; decode according to the superimposed electrical signals to obtain M ONUs Data sent by each ONU in the

The following exemplarily shows two decoding implementations.

Implementation mode A allows the electrical signals of the corresponding frequency bands in the superimposed electrical signals to pass through, and obtains the data sent by each of the M ONUs. One ONU corresponds to one frequency band, and the frequency bands corresponding to any two ONUs do not overlap each other.

Implementation method B: Multiply and accumulate the codeword corresponding to each ONU among the M ONUs and the superimposed electrical signal to obtain the data sent by each ONU. One ONU corresponds to one codeword, and any two codewords are orthogonal to each other.

In a possible implementation manner, the method further includes respectively emitting first injection light to each of the M ONUs, where the first injection light is used for the ONU to generate the first optical carrier, and the first optical carrier is used for To carry the electrical signal of the ONU, the wavelength of the first optical carrier is the same as the wavelength of the first injected light.

In a possible implementation manner, the method further includes respectively emitting N second injected lights to each of the M ONUs; wherein, the N second injected lights are used for the ONU to generate the second optical carrier, and the second The optical carrier is used to carry the electrical signal of the ONU. The wavelength of the N second injected lights is different, and the wavelength of the second optical carrier is the same as the wavelength of one of the N second injected lights. N is an integer greater than 1. .

In a possible implementation manner, the method may further include receiving the intrinsic light, performing mixing processing on the intrinsic light and the superimposed light signal to obtain a mixed signal; and converting the mixed signal into a superimposed electrical signal.

In another possible implementation, the method may include converting the superimposed optical signal into a superimposed current signal, and converting the superimposed current signal into a superimposed voltage signal.

In a possible implementation, the superimposed electrical signal includes superimposed analog electrical signals and superimposed digital electrical signals; the method may also include receiving the superimposed analog electrical signals from the photoelectric conversion module, and converting the superimposed analog electrical signals into superimposed digital electrical signals .

For the technical effects that can be achieved in any aspect of the above fifth aspect, reference may be made to the description of the beneficial effects in the above second aspect, which will not be repeated here.

Description of the drawings

Figure 1 is a schematic diagram of a PON system architecture provided by this application;

Figure 2 is a schematic diagram of uplink transmission provided by this application;

Figure 3 is a schematic structural diagram of an ONU provided by this application;

Figure 4a is a schematic diagram of the principle of an FDMA encoding and decoding provided by this application;

Figure 4b is a schematic diagram of the principle of a CDMA encoding and decoding provided by this application;

FIG. 5a is a schematic diagram of the principle of locking the emission wavelength of an ONU with injected light provided by this application;

FIG. 5b is a schematic diagram of the principle of another injection light locking ONU emission wavelength provided by this application;

FIG. 6 is a schematic structural diagram of an OLT provided by this application;

FIG. 7a is a schematic structural diagram of a coherent receiver provided by this application;

FIG. 7b is a schematic structural diagram of a photoelectric conversion module provided by this application;

FIG. 8 is a schematic diagram of an optical communication system architecture provided by this application;

Figure 9a is a schematic diagram of a PON system architecture provided by this application;

Figure 9b is a schematic diagram of another PON system architecture provided by this application;

FIG. 10 is a schematic diagram of the method flow of a data transmission method provided by this application.

Detailed ways

In order to make the purpose, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings.

Hereinafter, some terms in this application will be explained to facilitate the understanding of those skilled in the art.

1. Passive optical network (PON)

PON means that the optical distribution network (ODN) does not contain any electronic components and electronic power supplies. The ODN is composed of passive components such as splitters and does not require active electronic equipment. Therefore, it is called a passive optical network. Generally, a passive optical network includes an optical line terminal (OLT) installed in a central control station, and multiple optical network units (ONUs) installed in a user site.

2. Coherent detection

Coherent detection can also be called optical heterodyne detection. Coherent detection is based on the principle that coherent intrinsic light (or reference light) and incident signal light are mixed on the photosensitive surface. Among them, coherent intrinsic light and signal light means that the frequency of intrinsic light is very close to the frequency of signal light, and the intrinsic light and signal light can form a beat signal on the photosensitive surface of the photodetector.

3. Frequency division multiplexing access (FDMA)

FDMA divides the total bandwidth into multiple orthogonal channels. Each user occupies a frequency channel (carrier). In time, each channel can be used at the same time. In other words, different users occupy different frequencies, that is, different users use different carrier frequencies. At the receiving end, the corresponding filters can be used to distinguish (or select) the signals of each channel, and then the original signals of each channel can be recovered through the respective decoders.

4. Code division multiple access (code division multiple access, CDMA)

CDMA refers to the use of address code orthogonality to achieve multiple access communication, and each sender modulates the signals it sends with mutually orthogonal address codes. At the receiving end, the orthogonality of the address code is used, and the corresponding signal is selected from the mixed signal (or called the superimposed signal) through address identification. The CDMA system assigns one or more address codes (or code words) to each user. The address codes of each user are different from each other and orthogonal to each other.

Based on the foregoing content, as shown in FIG. 1, a schematic diagram of a PON system architecture provided for this application. The PON system is a multi-point to point (MP2P) system based on a tree-shaped network topology. The PON system includes an OLT, three ONUs (or optical network terminal (ONT) and ODN as examples) Description. The OLT is connected to each of the three ONUs through an ODN. The three ONUs in Figure 1 are ONU1, ONU2, and ONU3; the ODN includes a backbone fiber, a splitter, and a branch fiber. The splitter can also be called a splitter. It is an optical splitter. The splitter can be an optical fiber junction with multiple input ends and multiple output ends. It is mainly used for the coupling and distribution of optical signals. The OLT and the optical splitter are connected by a backbone fiber. The ONUs are connected by branch optical fibers. It should be understood that the OLT is a central office device, and the ONU is a terminal device. Figure 1 is only a schematic diagram. In addition, this application does not limit the number of OLTs and ONUs included in the PON system.

It should be noted that the transmission direction of the optical signal from the OLT to the ONU is called the downstream direction. The direction in which the optical signal is transmitted from the ONU to the OLT is called the upstream direction. The way the OLT transmits optical signals to the ONU can be broadcast, and the way the ONU transmits optical signals to the OLT can be unicast. It should be understood that for the upstream direction, the PON system is an MP2P system; for the downstream direction, the PON system is a point 2 multiple point (P2MP) system.

At present, the uplink transmission (that is, the transmission direction from the ONU to the OLT) usually adopts the time division multiplexing access mode. For example, time division multiple access (TDMA). With reference to Figure 1 above, in a possible implementation, the OLT can determine the distance between the OLT itself and each ONU, and then perform strict transmission timing on each ONU. The ONU can obtain timing information from the downstream signal sent by the OLT, and The OLT sends upstream signals in the time slots specified by the OLT. Among them, the PON based on this principle can also be called TDM-PON.

Please refer to Figure 2. Each dynamic bandwidth assignment (DBA) cycle (uplink transmission time) is divided into multiple time slots Ti (i = 1, 2, 3, ... 32, ...), and each Only one ONU in each time slot is arranged (or called allocation) to send upstream optical signals to the OLT, and each ONU sends optical signals in sequence in the order of the time slots allocated by the OLT. It should be noted that one ONU can be allocated one or more time slots.

Since the ONU transmits data (upstream direction) to the OLT using time division multiplexing technology, if multiple ONUs emit optical signals at the same time, it will cause the optical signals of each ONU to interfere with each other, which will cause the OLT to fail to receive the data from the ONU normally, which will lead to the entire PON. The business of the network is interrupted. In order to avoid interference between the optical signals of each ONU as much as possible, it is required that each ONU can only transmit optical signals when its time slot arrives, and cannot transmit optical signals during the rest of the time. Therefore, the data of the ONU that is ranked behind to send data will obviously arrive at the OLT later than the data of the ONU that is ranked in the front, especially when the number of ONUs ranked in the front is large, the delay of the data sent by the ONU that is ranked behind will be longer. Big. Moreover, the optical signal sent by the ONU to the OLT usually needs to carry some overhead data, such as the signal used for OLT clock synchronization, signal interaction (such as the bandwidth request information reported by the ONU to the OLT, operating temperature information, etc.), etc., which will cause Bandwidth wasted. It should be understood that the mode in which an ONU can only send optical signals when its time slot arrives is called "burst transmission mode", and the optical signal sent by an ONU in its own time slot is called a "burst packet", which is not in its own time slot. The ONU that randomly sends signals is called a rogue ONU.

In view of the above problems, this application proposes an ONU, an OLT, and an optical communication network. The ONU proposed in this application will be described in detail below with reference to Figure 3, Figure 4a, Figure 4b, Figure 5a, and Figure 5b; with reference to Figure 6, Figure 4a, Figure 4b, Figure 7a and Figures 7b, a detailed description of the OLT proposed by the present application; with reference to Figure 8, Figure 9a and Figure 9b, a detailed description of the optical communication system proposed by the present application.

Based on the foregoing content, as shown in FIG. 3, a schematic structural diagram of an ONU provided in this application. The ONU may include an encoding module and an electro-optical conversion module. Among them, the encoding module is used to orthogonally encode the data to be sent to obtain an electrical signal, and transmit the electrical signal to the electrical-optical conversion module; the electrical-optical conversion module is used to convert the received electrical signal into an optical signal, and through ODN, Send an optical signal to the OLT.

It should be noted that the data to be sent refers to the valid data to be sent by the ONU, such as the user's voice information, or the user's online information, etc. There is no overhead data, so the uplink bandwidth utilization rate is relatively high. The electrical signal obtained by orthogonally encoding the data to be sent is the encoded data. The encoded data obtained by different ONUs are different and mutually orthogonal, that is, the electrical signals obtained by different ONUs are different and mutually orthogonal.

Based on the foregoing ONU, the encoding module performs orthogonal encoding on the data to be sent by the ONU to obtain an electrical signal. Because of the orthogonal encoding, the electrical signals obtained by different ONUs are different from each other and orthogonal to each other. If there are multiple ONUs that need to send data, the electrical signals of the multiple ONUs do not interfere with each other, and multiple ONUs can transmit optical signals at the same time, that is, the data of multiple ONUs can overlap in time. In this way, data from multiple ONUs can reach the OLT at the same time, thereby helping to reduce the delay of data sent by the ONU. Moreover, there is no need to reserve blank time slots in time between ONUs, which can further reduce the time delay of data sent by ONUs. In other words, through the orthogonality coding of the coding module, it is equivalent to establishing a logical point-to-point link between each ONU and OLT (that is, ONU and OLT are independent point-to-point transmission channels). Interfere with each other. Furthermore, each ONU transmits valid data and does not need to transmit overhead data, thereby helping to save bandwidth.

In the following, each functional module shown in FIG. 3 is introduced and explained separately to give an exemplary specific implementation scheme.

One, coding module

In a possible implementation manner, the encoding module may be an FDMA encoder, or may also be a CDMA encoder. FDMA encoder refers to an encoder that uses FDMA encoding, FDMA encoding has orthogonality in the frequency domain; CDMA encoder refers to an encoder that uses CDMA encoding, and CDMA encoding has orthogonality in the time domain. In other words, orthogonality coding can be achieved through CDMA coding or FDMA coding, thereby ensuring that there is no interference between data transmitted by multiple ONUs.

As follows, taking the encoding module as an FDMA encoder or a CDMA encoder as an example, the detailed introduction will be given respectively.

Case 1, the encoding module is an FDMA encoder.

In a possible implementation manner, each ONU can correspond to a frequency band, and further, the FDMA encoder can determine the corresponding frequency band of the ONU, and multiply the data to be sent with the corresponding frequency band to obtain an electrical signal.

In a possible implementation, the frequency band corresponding to the ONU may be: the ONU receives the first configuration information from the OLT, and the first configuration information includes the frequency band corresponding to the ONU; or, the ONU and the OLT pre-appointed; or, the ONU in advance The frequency band corresponding to the ONU is stored locally, or it may be stipulated in the agreement, which is not limited in this application. In addition, the frequency bands corresponding to any two ONUs do not overlap each other.

In conjunction with FIG. 1, as shown in FIG. 4a, it is a schematic diagram of the principle of an FDMA encoding and decoding provided by this application. In Figure 4a, ONU1 corresponds to frequency band 1, ONU2 corresponds to frequency band 2, ONU3 corresponds to frequency band 3, the data to be sent on ONU1 is data 1, the data to be sent on ONU2 is data 2, and the data to be sent on ONU3 is data 3; the encoding module in ONU1 is FDMA encoding The encoding module in ONU2 is FDMA encoder 2, and the encoding module in ONU3 is FDMA encoder 3. FDMA encoder 1 is used to multiply data 1 and the corresponding frequency band 1 to obtain electrical signal 1 (represented by TX1) ; FDMA encoder 2 is used to multiply data 2 and the corresponding frequency band 2 to obtain electrical signal 2 (represented by TX2); FDMA encoder 3 is used to multiply data 3 and frequency band 3 to obtain electrical signal 3 ( Expressed by TX3). It should be understood that the frequency band can be represented by a sine wave, and the frequency bands occupied by any two ONUs do not overlap with each other. In addition, since the intermediate frequency is usually used as the transmitting frequency or the receiving frequency, the frequency band corresponding to the ONU can be selected as the intermediate frequency. It should be noted that the electrical signal 1 is the encoded data 1, the electrical signal 2 is the encoded data 2, and the electrical signal 3 is the encoded data 3.

In the second case, the encoding module is a CDMA encoder.

In a possible implementation, the CDMA encoder can achieve orthogonality in the time domain through orthogonal codes (codes). The codewords corresponding to each ONU are different from each other and orthogonal to each other. Exemplarily, the code words are respectively code1={1,1,1,1}, code2={1,-1,1,-1}, code3={1,1,-1,-1}, code1 , Code2 and code3 are different from each other and orthogonal to each other. It should be noted that the codeword includes but is not limited to 4 bits.

In a possible implementation manner, the ONU can determine the codeword corresponding to the ONU, and multiply the data with the corresponding codeword to obtain an electrical signal. Further, optionally, the codeword corresponding to the ONU may be: the ONU receives the second configuration information from the OLT, and the second configuration information includes the codeword corresponding to the ONU; or, the ONU and the OLT pre-appointed; or, the ONU is in advance The codeword corresponding to the ONU is stored locally, or it may be specified in the agreement, which is not limited in this application.

In conjunction with the foregoing Fig. 1, as shown in Fig. 4b, a schematic diagram of the principle of a CDMA encoding and decoding provided by this application. In Figure 4b, ONU1 corresponds to code word code1={1,1,1,1}, ONU2 corresponds to code word code2={1,-1,1,-1}, ONU3 corresponds to code word code3={1,1,- 1,-1} as an example. The data to be sent in ONU1 is data 1, the data to be sent in ONU2 is data 2, and the data to be sent in ONU3 is ONU3; the encoding module in ONU1 is CDMA encoder 1, the encoding module in ONU2 is CDMA encoder 2, and the encoding module in ONU3 is CDMA Encoder 3; CDMA encoder 1 is used to multiply data 1 and code1 to obtain electrical signal 1, TX1=data 1*(1+1+1+1); CDMA encoder 2 is used to combine data 2 and code2 Perform multiplication to obtain electrical signal 2, TX2=data 2*(1-1+1-1); CDMA encoder 3 is used to multiply data 3 and code3 to obtain electrical signal 3, TX3=data 3*( 1+1-1-1). It should be understood that the electrical signal 1 is the encoded data 1, the electrical signal 2 is the encoded data 2, and the electrical signal 3 is the encoded data 3.

Through the above CDMA encoder or FDMA encoder, the data to be sent from different ONUs can be processed orthogonally, and different and mutually orthogonal electrical signals can be obtained, so that multiple ONUs can send optical signals to the OLT at the same time and communicate with each other. No interference.

2. Electro-optical conversion module

In this application, the electro-optical conversion module can be used to convert the received electrical signal into an optical signal, and send the optical signal to the OLT through the ODN.

In a possible implementation, the electro-optical conversion module can be a distributed feedback (DFB) laser, a Fabry-Perot (Fabry-Perot, FP) laser, or an electro-absorption modulated laser (electlro-absorption modulated laser). , EML) etc. The FP laser, DFB laser and EML are all wavelength-tunable lasers. The so-called wavelength-tunable laser means that the wavelength of the output laser can be changed according to needs. Detailed descriptions are provided as follows.

DFB lasers mainly use semiconductor materials as the medium, including gallium antimonide (GaSb), gallium arsenide (GaAs), indium phosphide (InP), zinc sulfide (ZnS), etc., and have a high side-mode suppression ratio. suppression ratio, SMSR), where SMSR refers to the ratio of the maximum value of the main mode strength and the side mode strength, called the side mode suppression ratio, which is an important indicator of longitudinal mode performance. A grating is integrated in the active layer of the DFB laser, that is, the laser oscillation of the DFB laser is optical coupling formed by the grating. The output wavelength of the DFB laser can be adjusted by changing the current injected into the DFB laser, until the output wavelength of the DFB laser is equal to the wavelength of the injected light received by the DFB laser, and the DFB laser outputs the optical signal of this wavelength as the output optical signal. . In other words, the DFB laser receives the injected light and can emit light of the same wavelength as the injected light. Therefore, it is also called the DFB laser is locked by the injected light.

The principle of the EML output optical signal is the same as the principle of the above-mentioned DFB laser output optical signal. That is, by changing the magnitude of the current injected into the EML, the wavelength to be output by the EML can be adjusted until the wavelength to be output by the EML is equal to the wavelength of the injected light received by the EML, and the EML outputs the optical signal of this wavelength as the output optical signal.

The principle of FP laser output optical signal is: the injected light enters the optical resonant cavity of the FP laser, and the lasing wavelength of the optical resonant cavity of the FP laser can be forced to coincide with the wavelength of the injected light.

In a possible implementation, the electro-optical conversion module can be used to receive the first injection light emitted by the injection light source from the OLT, generate a first optical carrier based on the first injected light, and modulate the electrical signal onto the first optical carrier, Obtain the optical signal, and the wavelength of the first optical carrier is equal to the wavelength of the first injected light. In conjunction with Fig. 1, refer to FIG. 5a, if the wavelength of the first optical carrier ONU1, and ONU3 the ONU 2 receives the light wavelength of the first injection is injected from the OLT emission source are [lambda] _1, the ONU1 is generated λ _1, ONU2 The wavelength of the first optical carrier generated is also λ ₁ , and the wavelength of the first optical carrier generated by ONU 3 is also λ ₁ . For the introduction of the injection light source of the OLT, please refer to the introduction of the following injection light source, which will not be repeated here.

In another possible implementation, the electro-optical conversion module can be used to receive N second injection lights emitted by the injection light source from the OLT, generate a second optical carrier based on the N second injection lights, and modulate the electrical signal to On the second optical carrier, an optical signal is obtained, where the wavelength of the second optical carrier is the same as the wavelength of one of the N second injected lights, and N is an integer greater than 1. It should be understood that the number N of second injected lights emitted by the OLT is greater than or equal to the number of ONUs in the optical communication system where the ONU is located.

Further, optionally, the electro-optical conversion module can also be used to receive instruction information from the OLT, the instruction information is used to instruct the electro-optical conversion module to select which wavelength of the second injected light, that is, the wavelength of the generated second optical carrier must be related to which wavelength The wavelength of the two injected light is the same. Or, it can also be understood that the OLT allocates the second injection light of one wavelength to the ONU, and the ONU tunes the wavelength to the allocated wavelength.

With reference to Figure 1 above, refer to Figure 5b. If ONU1, ONU2, and ONU3 receive the three second injection lights emitted by the injection light source from the OLT. The wavelengths of the three second injection lights are respectively λ ₁ , λ ₂ and λ ₃ , the second optical carrier generated by ONU1 The wavelength of can be λ ₁ , the wavelength of the second optical carrier generated by ONU ₂ is also λ 2, and the wavelength of the second optical carrier generated by ONU ₃ is also λ 3. Of course, the wavelength of the second optical carrier generated by ONU1 _{can be λ 2} , the wavelength of the second optical carrier generated by ONU _{2 is also λ 3} , and the wavelength of the second optical carrier _{generated by ONU 3 is also λ 1} ; or the second optical carrier generated by ONU 1 The wavelength of the second optical carrier can be λ ₃ , the wavelength of the second optical carrier generated by ONU 2 is also λ ₁ , the wavelength of the second optical carrier generated by _{ONU 3 is also λ 2,} etc. Figure 5b is only an example, the ONU generates The wavelength of the second optical carrier can be determined according to the instruction information from the OLT, or it can also be understood that the OLT allocates a wavelength of second injection light to the ONU, and the ONU tunes the wavelength to the allocated wavelength. For the introduction of the injection light source of the OLT, please refer to the introduction of the following injection light source, which will not be repeated here.

In another possible implementation manner, the electro-optical conversion module can also randomly generate a third optical carrier of one wavelength; or, the electro-optical conversion module adjusts itself to generate a third optical carrier of one wavelength, and modulates the electrical signal to the third optical carrier. , Get the light signal.

As shown in FIG. 6, a schematic structural diagram of an OLT provided in this application. The OLT includes a photoelectric conversion module and a decoding module; the photoelectric conversion module is used to receive the superimposed optical signal through the ODN, convert the superimposed optical signal into a superimposed electrical signal, and transmit the superimposed electrical signal to the decoding module, and the superimposed optical signal comes from M optical networks The M optical signals of the unit ONU are superimposed. The superimposed electrical signals include M mutually orthogonal electrical signals. M electrical signals correspond to M optical signals one-to-one, and M ONUs correspond to M optical signals one-to-one. It is an integer greater than 1; the decoding module is used to decode according to the superimposed electrical signal to obtain the data sent by each of the M ONUs.

It should be noted that the superposition of optical signals refers to the superposition of the power of M optical signals. With reference to Figure 1 above, for example, the power of ONU1 is 1mW, the power of ONU2 is 1mW, the power of ONU3 is 1mW, and the superimposed power is 1+1+1=3mW. The superimposed electrical signal is obtained by superimposing M electrical signals. For example, electrical signal 1 is represented by TX1, electrical signal 2 is represented by TX2, electrical signal 3 is represented by TX3, and electrical signal 1, electrical signal 2 and electrical signal 3 are superimposed , The superimposed electrical signal obtained is TX=TX1+TX2+TX3, where the electrical signal 1, the electrical signal 2, and the electrical signal 3 are different and orthogonal to each other.

Based on the above OLT, the OLT receives the superimposed optical signal, converts the superimposed optical signal into a superimposed electrical signal through the photoelectric conversion module, and decodes the superimposed electrical signal by the decoding module to simultaneously obtain M data from M ONUs. In this way, it helps to reduce the time delay of the data sent by the M ONUs. Further, the superimposed electrical signals are M mutually orthogonal electrical signals, which do not interfere with each other, so that independent and non-interfering data sent by each ONU can be obtained.

Each functional module shown in FIG. 6 will be introduced and explained separately below to give an exemplary specific implementation scheme.

Three, photoelectric conversion module

In this application, the photoelectric conversion module is used to convert the superimposed optical signal into the superimposed electrical signal, and the structure of two photoelectric conversion modules is exemplarily shown as follows.

Structure one, the photoelectric conversion module is a coherent receiver.

As shown in FIG. 7a, it is a schematic structural diagram of a coherent receiver provided in this application. The coherent receiver includes an intrinsic light source, an optical mixer and a balanced detector. The intrinsic light source is used to emit intrinsic light to the optical mixer. The optical mixer is used to perform mixing processing on the received intrinsic light and superimposed optical signal to obtain a mixed signal, and transmit the mixed signal to a balanced detector. In other words, one end of the mixer inputs the intrinsic light, and the other end inputs the superimposed optical signal. In a possible implementation, the frequency of the mixing signal output by the mixer is equal to the sum and difference of the frequencies of the two input signals. Generally, a mixer can be used to generate an intermediate frequency signal: cosαcosβ=[cos(α+β)+cos(α-β)]/2, cosα and cosβ are the two input signals (such as superimposed light signal and intrinsic light), cos(α+β) and cos(α-β) are output mixing signals. The balance detector is used to convert the mixed frequency signal into a superimposed electrical signal and transmit the superimposed electrical signal to the decoding module. Further, optionally, the balanced detector may include a photodiode (PD) and a TIA.

Structure two, the photoelectric conversion module includes APD and TIA.

As shown in FIG. 7b, a schematic structural diagram of a photoelectric conversion module provided in this application. The photoelectric conversion module may include APD and TIA. APD is used to receive superimposed optical signals and convert the superimposed optical signals into superimposed current signals; TIA is used to convert the received superimposed current signals into superimposed voltage signals.

The above-mentioned APD is based on the principle of photoelectric effect, which converts the received superimposed light signal into a superimposed current signal. Moreover, the APD has a gain of 10 to 200 times, which can improve the sensitivity of receiving superimposed optical signals. In the prior art, since the electrical power of the burst packet is different, and the OLT needs a unified electrical signal power, the TIA device in the prior art also needs to have a fast amplification switching function. That is, in the case of high burst packets, switch to low magnification; in the case of low power burst packets, switch to high magnification. However, in this application, since the superimposed electrical signals are M electrical signals that are different from each other and orthogonal to each other, there is no need for burst TIA, that is, TIA does not need to achieve rapid amplification switching function, and can directly reuse existing TIA in technology, therefore, the cost of integrating OLT is lower.

Fourth, the decoding module

In a possible implementation manner, the decoding module may be an FDMA decoder, or may also be a CDMA decoder. After the data from each ONU is encoded by the FDMA encoder of the ONU, the encoded data is obtained. The encoded data of each ONU occupies different frequency bands. Therefore, after filtering by the FDMA decoder, the independent data can be obtained. The data of each ONU that does not interfere with each other. After the data from each ONU is encoded by the CDMA encoder of the ONU, the encoded data is obtained. The data obtained after the encoding of each ONU is multiplied and accumulated with the corresponding codeword. It is not equal to zero, and is multiplied and accumulated with other codewords. Operation is equal to zero.

In a possible implementation, the FDMA decoder may include K filters, each of the K filters allows a different frequency band to pass, and each of the K filters is used to allow superimposition of electrical signals. The electrical signals of the corresponding frequency bands in the pass, one ONU corresponds to one frequency band, the frequency bands corresponding to any two ONUs do not overlap each other, and K is a positive integer. Since the data of each ONU occupies a different frequency band, after filtering by the corresponding filter, independent and non-interfering data of each ONU can be obtained.

It should be noted that K is usually equal to M, that is, one ONU corresponds to one filter. K can also be less than M, that is, multiple ONUs correspond to one filter. For example, two ONUs correspond to one filter, and the filter may allow the frequency bands corresponding to the two ONUs to pass. Of course, K can also be greater than M, and one ONU corresponds to one filter, that is, some filters are used to correspond to the newly added ONU when the ONU is newly added.

Based on the above situation 1, refer to the above Figure 4a, the superimposed electrical signal received by the FDMA decoder is RX, RX=TX=TX1+TX2+TX3, filter 1 allows the electrical signal 1 of frequency band 1 to pass, and filter 2 allows frequency band 2 The electrical signal 2 of the frequency band passes through, and the filter 3 allows the electrical signal 3 of the frequency band 3 to pass. In other words, when the superimposed electrical signal RX passes through the filter 1, the electrical signal 1 can be obtained; when the superimposed electrical signal RX passes through the filter 2, the electrical signal 2 can be obtained; and when the superimposed electrical signal RX passes through the filter 3, the electrical signal 3 can be obtained.

Further, optionally, since the frequency band corresponding to the ONU is usually the intermediate frequency, but the decoding and recovery of the electrical signal are completed in the low frequency band, in order to facilitate the rapid recovery of the data of each ONU, the FDMA decoder may also include K down-conversions The K down-converters and K filters have a one-to-one correspondence, and each down-converter in the K down-converters is used to convert a corresponding electrical signal into a low-frequency electrical signal (such as a baseband signal). Exemplarily, the down-converter 1 can convert the electrical signal 1 into a low-frequency electrical signal 1, the down-converter 2 can convert the electrical signal 2 into a low-frequency electrical signal 2, and the down-converter 3 can convert the electrical signal 2 It is a low-frequency electrical signal 3, where the low-frequency electrical signal 1, the low-frequency electrical signal 2 and the low-frequency electrical signal 3 may all be baseband signals.

Based on the above situation two, referring to the above figure 4b, the superimposed electrical signal received by the CDMA decoder is RX, RX=TX=TX1+TX2+TX3=data 1*(1+1+1+1)+data2*(1 -1+1-1)+Data 3*(1+1-1-1). The process of CDMA decoder decoding ONU1's data 1 can be: CDMA decoder uses ONU1's corresponding code word code1 to multiply and accumulate with the superimposed electrical signal RX, namely: RX*code1=[data1*(1+1+1+1) +Data2*(1-1+1-1)+Data3*(1+1-1-1)]*(1+1+1+1)=Data1*(1+1+1+1) *(1+1+1+1)+data2*(1-1+1-1)*(1+1+1+1)+data3*(1+1-1-1)*(1+ 1+1+1)=data1*(1+1+1+1)+data2*(1-1+1-1)*+data3*(1+1-1-1)=4*data 1+0+0=4*data 1. Due to the orthogonality of orthogonal codes, ONU2 and ONU3 are equal to 0 after decoding, and only data 1 of ONU1 is decoded.

The process of CDMA decoder decoding ONU2's data 2 is: CDMA decoder uses the codeword code2 corresponding to ONU2 to multiply and accumulate with the superimposed electrical signal RX, namely: RX*code2=[data1*(1+1+1+1) +Data2*(1-1+1-1)+Data3*(1+1-1-1)]*(1-1+1-1)=Data1*(1+1+1+1) *(1-1+1-1)+data2*(1-1+1-1)*(1-1+1-1)+data3*(1+1-1-1)*(1- 1+1-1)=Data 1*(1-1+1-1)+Data 2*(1+1+1+1)*+Data 3*(1-1-1+1)=0+4 *Data 2+0=4*Data 2. Due to the orthogonality of orthogonal codes, ONU1 and ONU3 are equal to 0 after being decoded, and only data 2 of ONU2 is decoded.

The process of CDMA decoder decoding ONU3 data is: CDMA decoder uses the codeword code3 corresponding to ONU3 to multiply and accumulate with RX, namely: RX*code3=[data1*(1+1+1+1)+data2* (1-1+1-1)+data3*(1+1-1-1)]*(1+1-1-1)=data1*(1+1+1+1)*(1+ 1-1-1)+data2*(1-1+1-1)*(1+1-1-1)+data3*(1+1-1-1)*(1+1-1- 1)=Data 1*(1+1-1-1)+Data 2*(1-1-1+1)*+Data 3*(1+1+1+1)=0+0+4*Data 3=4*Data 3. Due to the orthogonality of orthogonal codes, ONU1 and ONU2 are equal to 0 after being decoded, and only data 3 of ONU3 is decoded.

In this application, superimposed electrical signals may include superimposed analog electrical signals and superimposed digital electrical signals. The above-mentioned electro-optical conversion module can convert the superimposed optical signal into a superimposed analog electric signal. Further, optionally, the OLT may also include an analog-to-digital conversion module, which is used to receive the superimposed analog electrical signal from the photoelectric conversion module, convert the superimposed analog electrical signal into a superimposed digital electrical signal, and send it to the decoding module Transmit superimposed digital electrical signals. Further, optionally, in order to improve the efficiency of the OLT in restoring the data of the ONU, the OLT may further include an injection light source. As follows, the analog-to-digital conversion module and the injection light source are introduced in detail.

Five, analog-to-digital conversion module

If the photoelectric conversion module is the first structure above, the analog-to-digital conversion module is used to receive the superimposed analog electrical signal from the coherent receiver, convert the superimposed analog electrical signal into a superimposed digital electrical signal, and transmit the superimposed digital electrical signal to the decoding module.

If the photoelectric conversion module is the second structure above, the analog-to-digital conversion module is used to receive the superimposed analog voltage signal from the TIA, convert the superimposed analog voltage signal into a superimposed digital voltage signal, and transmit the superimposed digital voltage signal to the decoding module.

In a possible implementation manner, the analog-to-digital conversion module may be an ADC, and the ADC may convert the input analog electrical signal into a digital electrical signal and output, and the output digital electrical signal is used by the data processing module to process the digital signal. In this way, a burst ADC is not needed, and the ADC in the prior art can be directly reused, thereby helping to reduce the cost of integrated OLT.

Further, optionally, the OLT may also include a data processing module, and the data processing module may be used for clock signal recovery and the like.

Six, inject the light source

In a possible implementation, the injection light source may be a DFB laser or a multi-wavelength light source lamp.

Based on the wavelength of the injection light emitted by the injection light source, the following exemplarily shows two possible ways for the injection light source to emit the injection light.

Method 1, the injection light source emits injection light of a single wavelength.

In a possible implementation manner, the OLT may further include an injection light source, and the injection light source may be used to respectively emit the first injection light to each ONU of the M ONUs. The first injected light may also be referred to as the first seed light. After the ONU receives the first injected light, it can generate a first optical carrier with the same wavelength as the first injected light. For details, please refer to the introduction of FIG. 5a, which will not be repeated here.

Method 2, the injection light source emits injection light of multiple wavelengths.

In a possible implementation manner, the OLT further includes an injection light source, and the injection light source can be used to respectively emit N second injection lights to each of the M ONUs, where N is an integer greater than 1. After the ONU receives the N second injected lights, it can select a second injected light from the N second injected lights and generate a second optical carrier with the same wavelength as the selected second injected light. For details, refer to the above The introduction of Figure 5b will not be repeated here.

It should be noted that if the photoelectric conversion module is the coherent receiver in FIG. 7a, the injected light source can also be used as the intrinsic light source of the coherent receiver. It should be understood that the intrinsic light source of the coherent receiver may also be an independent light source.

In a possible implementation manner, the OLT may also include a medium access control (MAC) module, and the MAC module may configure the first configuration information or the second configuration information.

Based on the above content, this application provides an optical communication system. Fig. 8 exemplarily shows a schematic structural diagram of an optical communication system provided by the present application. The optical communication system may include an OLT, M ONUs, and an ODN. In the example of FIG. 8, M=3 is taken as an example, that is, it includes ONU1, ONU2, and ONU3, and the OLT can communicate with ONU1, ONU2, and ONU3 respectively through ODN. Among them, the ONU may include an electro-optical conversion module and an encoding module; the OLT may include an opto-electronic conversion module and a decoding module. Further, optionally, the OLT may also include an analog-to-digital conversion module, a data processing module, and an injection light source. For the introduction and description of each module, please refer to the above-mentioned related content, which will not be repeated here.

Further, optionally, the ODN may include a backbone fiber, an optical splitter, and M branch fibers. The M branch fibers correspond to the M ONUs one-to-one, and the splitter and each ONU of the M ONUs can pass through the corresponding branch fiber. Connection, the OLT and the optical splitter are connected through the backbone fiber, and M is an integer greater than 1. Each ONU of the M ONUs is used to send the corresponding optical signal to the optical splitter through the corresponding branch fiber; the optical splitter is used to combine the received M optical signals, that is, to converge the optical signal from each branch fiber , Obtain the superimposed optical signal, and send the superimposed optical signal to the OLT through the backbone fiber. With reference to Figure 8 above, ONU1 sends optical signal 1 to the optical splitter through the corresponding branch fiber, ONU2 sends optical signal 2 to the optical splitter through the corresponding branch fiber, and ONU3 sends optical signal 3 to the optical splitter through the corresponding branch fiber. The optical splitter is used to converge the optical signal 1, the optical signal 2 and the optical signal 3 to obtain the superimposed optical signal, that is, input three optical signals, output one superimposed optical signal, and send the superimposed optical signal to the OLT through the backbone fiber. It should be understood that the optical splitter is a passive device that can perform simple power superposition on the input multiple optical signals.

For the downstream direction, one optical signal sent by the OLT passes through the optical splitter and is divided into M optical signals and sent to M ONUs. Each ONU can selectively receive downstream data with the same number as the one set by itself, and discard other data. For example, the injection light source of the OLT emits one optical signal including one first injection light, and after passing through the optical splitter, it is divided into M first injection lights and sent to M ONUs respectively. With reference to Figure 5a, the injection light source of the OLT emits an optical signal including one first injection light. After passing through an optical splitter, it is divided into three first injection lights and sent to ONU1, ONU2, and ONU3 via corresponding branch fibers. For another example, the injection light source of the OLT emits one optical signal including N second injected lights, and after passing through the splitter, it is divided into M optical signals, and each optical signal includes N second injected lights, which are respectively sent to M ONU. With reference to Figure 5b, the injection light source of the OLT emits one optical signal including three second injection lights. After the splitter, the optical signal is divided into three paths, each including three second injection lights, and each optical signal passes through the corresponding The branch fiber is transmitted to ONU1, ONU2 and ONU3.

For the upstream direction, the optical splitter can converge the M optical signals from the M ONUs into a superimposed optical signal, which is transmitted to the OLT via the backbone optical fiber.

It should be noted that, in the optical communication system, the number of wavelengths of the first injection light or the number of wavelengths of the second injection light emitted by the OLT is greater than or equal to the number of ONUs.

The optical communication system in this application may be a PON system. The PON system can be a gigabit-capable PON (GPON) system, an Ethernet passive optical network (ethernet PON, EPON) system, a ten gigabit Ethernet passive optical network (10Gb/s ethernet passive optical network, 10G-EPON) system, time and wavelength division multiplexing passive optical network (TWDM-PON), 10 gigabit-capable passive optical network, XG-PON ) System or 10-gigabit-capable symmetric passive optical network (XGS-PON) system, etc. New technologies evolving in the future will increase the PON rate to 25Gbps, 50Gbps or even 100Gbps. Therefore, this application can also apply a higher transmission rate PON system.

In a possible implementation, the PON system may include 64 to 128 ONUs. Exemplarily, if the PON system includes 64 ONUs, 32 ONUs need to send data, and 32 ONUs do not need to send data. Based on the above solution, the data delay of 32 ONUs that need to send data can be guaranteed to be as small as possible. .

Based on the foregoing, two specific implementations of the foregoing optical communication system are given below in combination with specific hardware structures. In order to further understand the architecture of the above-mentioned optical communication system and the realization process of data transmission.

As shown in FIG. 9a, it is a schematic diagram of the architecture of a PON system provided in this application. The PON system may include ONU1, ONU2, ONU3, OLT and ODN. Among them, ONU includes FDMA encoder or CDMA encoder, and DFB; OLT includes APD, TIA, ADC, data processing module, FDMA decoder or CDMA decoder, and injection light source; ODN includes backbone fiber, branch fiber and splitter. It should be understood that if the ONU includes an FDMA encoder, the OLT includes an FDMA decoder; if the ONU includes a CDMA encoder, the OLT includes a CDMA decoder. For each structure, please refer to the description of the above-mentioned related content respectively, which will not be repeated here.

As shown in FIG. 9b, it is a schematic structural diagram of another PON system provided by this application. The PON system may include ONU1, ONU2, ONU3, OLT and ODN. Among them, ONU includes FDMA encoder or CDMA encoder, and DFB; OLT includes coherent receiver, ADC, data processing module, FDMA decoder or CDMA decoder, and injection light source; ODN includes backbone fiber, branch fiber and optical splitter. It should be understood that if the ONU includes an FDMA encoder, the OLT includes an FDMA decoder; if the ONU includes a CDMA encoder, the OLT includes a CDMA decoder. The difference from Fig. 9a above is that the photoelectric conversion module in the PON system is a coherent receiver.

Based on the PON system shown in Fig. 9a or Fig. 9b, the TDMA burst mode of the upstream signal of the PON system in the prior art can be converted into a continuous mode in which all ONUs send data by encoding the data to be sent by the ONU. It can solve the problems faced by the current burst mode of the PON system, such as the high technical difficulty of burst TIA and the immaturity of the burst ADC industry chain.

Based on the above content and the same concept, this application also provides a data transmission method. Referring to Fig. 10, this method can be applied to the system shown in Fig. 1, Fig. 8, Fig. 9a or Fig. 9b. The data transmission method may include the following steps.

Step 1001: The ONU performs orthogonality coding on the data to be sent to obtain an electrical signal.

The following exemplarily shows two implementations of orthogonal encoding of the data to be sent by the ONU.

Implementation method 1: Determine the frequency band corresponding to the ONU, and multiply the data with the corresponding frequency band to obtain an electrical signal. It should be understood that different ONUs correspond to different frequency bands, and the frequency bands corresponding to any two ONUs do not overlap.

Further, optionally, first configuration information from the OLT may be received, where the first configuration information includes the frequency band corresponding to the ONU.

Implementation mode 2: Determine the codeword corresponding to the ONU, and multiply the data with the corresponding codeword to obtain an electrical signal. It should be understood that different ONUs correspond to different codewords, and different codewords are orthogonal to each other.

Further, optionally, second configuration information from the OLT may be received, where the second configuration information includes a codeword corresponding to the ONU.

This step 1001 can be performed by the encoding module in the ONU. For possible implementations, please refer to the introduction of the encoding module, which will not be repeated here.

Step 1002: The ONU converts the electrical signal into an optical signal, and transmits the optical signal to the ODN.

Exemplarily, the optical communication system includes M ONUs. In a possible implementation manner, each ONU of the M ONUs can respectively receive the first injection light emitted from the OLT, and generate the first light according to the first injection light. The carrier wave modulates the electrical signal onto the first optical carrier to obtain the optical signal, wherein the wavelength of the first optical carrier is equal to the wavelength of the first injected light. In another possible implementation manner, each ONU of the M ONUs can respectively receive N second injected lights from the OLT, select a second injected light from the N second injected lights, and select the second injected light according to the selected The second injected light generates a second optical carrier, and modulates the electrical signal onto the second optical carrier to obtain an optical signal. The wavelength of the second optical carrier is the same as the wavelength of the selected second injected light, and N is an integer greater than 1. .

This step 1002 can be performed by the above-mentioned electro-optical conversion module. For possible implementation manners, refer to the introduction of the above-mentioned electro-optical conversion module, which will not be repeated here.

Step 1003: The ODN superimposes the M optical signals from the M ONUs to obtain the superimposed optical signal, and sends the superimposed optical signal to the OLT. Correspondingly, the OLT receives the superimposed optical signal through the ODN.

This step 1003 is optional. The possible implementation of ODN can be found in the above-mentioned related description, which will not be repeated here.

Step 1004: The OLT converts the received superimposed optical signal into a superimposed electrical signal.

Here, the superimposed electrical signal includes M mutually orthogonal electrical signals, M electrical signals correspond to M optical signals one-to-one, M ONUs correspond to M optical signals one-to-one, and M is an integer greater than 1.

In a possible implementation, the method may further include receiving intrinsic light, performing mixing processing on the intrinsic light and the superimposed light signal to obtain a mixed signal, and converting the mixed signal into a superimposed electrical signal.

In another possible implementation, the method may include converting the superimposed optical signal into a superimposed current signal, and converting the superimposed current signal into a superimposed voltage signal.

This step 1004 can be performed by the above-mentioned photoelectric conversion module. For possible implementations, refer to the introduction of the above-mentioned photoelectric conversion module, which will not be repeated here.

In step 1005, the OLT may decode according to the superimposed electrical signal to obtain the data sent by each ONU of the M ONUs.

The following exemplarily shows two decoding implementations.

Implementation mode A allows the electrical signals of the corresponding frequency bands in the superimposed electrical signals to pass through, and obtains the data sent by each of the M ONUs. One ONU corresponds to one frequency band, and the frequency bands corresponding to any two ONUs do not overlap each other.

Implementation method B: Multiply and accumulate the codeword corresponding to each ONU among the M ONUs and the superimposed electrical signal to obtain the data sent by each ONU. One ONU corresponds to one codeword, and any two codewords are orthogonal to each other.

This step 1005 can be performed by the above-mentioned decoding module. For possible implementations, please refer to the introduction of the above-mentioned decoding module, which will not be repeated here.

In a possible implementation manner, the superimposed electrical signal includes a superimposed analog electrical signal and a superimposed digital electrical signal; the superimposed electrical signal received by the OLT is a superimposed analog electrical signal. Further, the superimposed analog electrical signal can be converted into a superimposed digital electrical signal.

From the above steps 1001 to 1005, it can be seen that the ONU performs orthogonality coding on the data to be sent to obtain the electrical signal. Because of the orthogonality coding, the electrical signals obtained by different ONUs are different from each other and orthogonal to each other. If there are multiple ONUs that need to send data, the electrical signals of the multiple ONUs do not interfere with each other, and multiple ONUs can transmit optical signals to the OLT at the same time, that is, the data of multiple ONUs can overlap in time. In this way, data from multiple ONUs can reach the OLT at the same time, thereby helping to reduce the delay of data sent by the ONU. It is equivalent to establishing a logical point-to-point link between each ONU and OLT (that is, ONU and OLT are point-to-point independent transmission channels), and different links will not interfere with each other.

In the various embodiments of this application, if there are no special instructions and logical conflicts, the terms and/or descriptions between different embodiments are consistent and can be mutually cited. The technical features in different embodiments are based on their inherent Logical relationships can be combined to form new embodiments.

In this application, "plurality" means two or more. "And/or" describes the association relationship of the associated objects, indicating that there can be three relationships, for example, A and/or B, which can mean: A alone exists, A and B exist at the same time, and B exists alone, where A, B can be singular or plural. In the text description of this application, the character "/" generally indicates that the associated objects before and after are in an "or" relationship. In the formula of this application, the character "/" indicates that the associated objects before and after are in a "division" relationship.

It can be understood that the various numerical numbers involved in this application are only for easy distinction for description, and are not used to limit the scope of the embodiments of this application. The size of the sequence number of the above processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic. The terms "first", "second" and other similar expressions are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. In addition, the terms "including" and "having" and any variations of them are intended to cover non-exclusive inclusions, for example, including a series of steps or units. The method, system, product, or device need not be limited to those clearly listed steps or units, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or devices.

Although the application has been described in combination with specific features and embodiments, it is obvious that various modifications and combinations can be made without departing from the spirit and scope of the application. Correspondingly, the present specification and drawings are merely exemplary descriptions of the solutions defined by the appended claims, and are deemed to have covered any and all modifications, changes, combinations or equivalents within the scope of the present application.

Obviously, those skilled in the art can make various changes and modifications to this application without departing from the spirit and scope of the present invention. In this way, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims (32)

1. An optical network unit ONU, which is characterized in that it comprises an encoding module and an electro-optical conversion module;

   The encoding module is configured to perform orthogonal encoding on the data to be sent to obtain an electrical signal, and transmit the electrical signal to the electro-optical conversion module;

   The electrical-optical conversion module is configured to convert the received electrical signal into an optical signal, and send the optical signal to an optical line terminal OLT through an optical distribution network ODN.
2. The ONU according to claim 1, wherein the encoding module is a frequency division multiplexing access FDMA encoder;

   The encoding module is specifically used for:

   Determine the frequency band corresponding to the ONU;

   The data and the corresponding frequency band are multiplied to obtain the electrical signal.
3. The ONU according to claim 1 or 2, wherein the encoding module is further used for:

   Receiving first configuration information from the OLT, where the first configuration information includes the frequency band corresponding to the ONU.
4. The ONU according to claim 1, wherein the encoding module is a code division multiplexing access CDMA encoder;

   The encoding module is specifically used for:

   Determine the codeword corresponding to the ONU;

   The data and the corresponding codeword are multiplied to obtain the electrical signal.
5. The ONU according to claim 1 or 4, wherein the encoding module is further used for:

   Receiving second configuration information from the OLT, where the second configuration information includes a codeword corresponding to the ONU.
6. The ONU according to any one of claims 1 to 5, wherein the electro-optical conversion module is specifically used for:

   Receiving the first injection light emitted from the injection light source of the OLT;

   Generating a first optical carrier according to the first injected light, the wavelength of the first optical carrier is equal to the wavelength of the first injected light;

   The electrical signal is modulated onto the first optical carrier to obtain the optical signal.
7. The ONU according to any one of claims 1 to 5, wherein the electro-optical conversion module is specifically used for:

   Receiving N second injected lights emitted from the injection light source of the OLT, where N is an integer greater than 1;

   Generating a second optical carrier according to the N second injected lights, the wavelength of the second optical carrier being the same as the wavelength of one second injected light in the N second injected lights;

   The electrical signal is modulated onto the second optical carrier to obtain the optical signal.
8. An optical line terminal OLT, which is characterized in that it comprises a photoelectric conversion module and a decoding module;

   The photoelectric conversion module is configured to receive the superimposed optical signal through an optical distribution network ODN, convert the superimposed optical signal into a superimposed electrical signal, and transmit the superimposed electrical signal to the decoding module, and the superimposed optical signal is M optical signals from M optical network units ONU are superimposed, and the superimposed electrical signals include M mutually orthogonal electrical signals, and the M electrical signals correspond to the M optical signals in a one-to-one correspondence. The M ONUs correspond to the M optical signals one-to-one, and the M is an integer greater than 1;

   The decoding module is configured to perform decoding according to the superimposed electrical signal to obtain data sent by each of the M ONUs.
9. The OLT according to claim 8, wherein the decoding module is a frequency division multiplexing access FDMA decoder, the FDMA decoder includes K filters, and each of the K filters is The frequency bands allowed to pass are different, and the K is a positive integer;

   Each of the K filters is used to allow the electrical signal of the corresponding frequency band in the superimposed electrical signal to pass. One ONU corresponds to one frequency band, and the frequency bands corresponding to any two ONUs do not overlap each other.
10. 8. The OLT according to claim 8, wherein the decoding module is a code division multiplexing access CDMA decoder;

    The CDMA decoder is used for multiplying and accumulating the codeword corresponding to each ONU in the M ONUs with the superimposed electrical signal to obtain the data sent by each ONU in the M ONUs, and one ONU corresponds to For a codeword, any two codewords are orthogonal to each other.
11. The OLT according to any one of claims 8 to 10, wherein the OLT further comprises an injection light source;

    The injection light source is configured to respectively emit first injection light to each ONU of the M ONUs;

    Wherein, the first injected light is used by the ONU to generate a first optical carrier, the first optical carrier is used to carry an electrical signal of the ONU, and the wavelength of the first optical carrier is the same as that of the first injected light. The wavelength is the same.
12. The OLT according to any one of claims 8 to 10, wherein the OLT further comprises an injection light source;

    The injection light source is configured to respectively emit N second injection lights to each ONU of the M ONUs;

    Wherein, the N second injected lights are used for the ONU to generate a second optical carrier, the second optical carrier is used to carry the ONU's electrical signal, and the wavelengths of the N second injected lights are different, so The wavelength of the second optical carrier is the same as the wavelength of one of the N second injected lights, and the N is an integer greater than 1.
13. The OLT according to any one of claims 8 to 12, wherein the photoelectric conversion module is a coherent receiver, and the coherent receiver includes an intrinsic light source, an optical mixer, and a balanced detector;

    The intrinsic light source is used to emit intrinsic light to the optical mixer;

    The optical mixer is configured to perform mixing processing on the received intrinsic light and the superimposed optical signal to obtain a mixing signal, and transmitting the mixing signal to the balanced detector;

    The balance detector is used for converting the mixing signal into a superimposed electric signal, and transmitting the superimposed electric signal to the decoding module.
14. The OLT according to any one of claims 8 to 12, wherein the photoelectric conversion module comprises an avalanche photodiode APD and a transimpedance amplifier TIA;

    The APD is configured to receive the superimposed optical signal, convert the superimposed optical signal into a superimposed current signal, and transmit the superimposed current signal to the TIA;

    The TIA is used to convert the received superimposed current signal into a superimposed voltage signal.
15. The OLT according to any one of claims 8 to 14, wherein the superimposed electrical signal comprises a superimposed analog electrical signal and a superimposed digital electrical signal; the OLT further comprises an analog-to-digital conversion module;

    The analog-to-digital conversion module is configured to receive the superimposed analog electrical signal from the photoelectric conversion module, convert the superimposed analog electrical signal into a superimposed digital electrical signal, and transmit the superimposed digital signal to the decoding module. electric signal.
16. An optical communication system, characterized by comprising M optical network unit ONUs according to any one of claims 1 to 7, an optical line terminal OLT according to any one of claims 8 to 15, and an optical distribution network ODN;

    Wherein, the OLT communicates with each ONU of the M ONUs through the ODN.
17. The optical communication system according to claim 16, wherein the ODN includes a backbone fiber, an optical splitter, and M branch fibers, and the M branch fibers correspond to the M ONUs in a one-to-one correspondence. And each ONU of the M ONUs are connected through a corresponding branch optical fiber, the OLT and the optical splitter are connected through the backbone optical fiber, and the M is an integer greater than 1;

    Each ONU of the M ONUs is configured to send an optical signal to the optical splitter through the corresponding branch optical fiber;

    The optical splitter is configured to combine the M received optical signals to obtain the superimposed optical signal, and send the superimposed optical signal to the OLT through the backbone fiber.
18. A data transmission method, characterized in that the method is applied to an ONU of an optical network unit, and the method includes:

    Perform orthogonality encoding on the data to be sent to obtain an electrical signal;

    The electrical signal is converted into an optical signal, and the optical signal is sent to the optical line terminal OLT through the optical distribution network ODN.
19. The method according to claim 18, wherein the performing orthogonality coding on the data to be sent to obtain the electrical signal comprises:

    Determine the frequency band corresponding to the ONU;

    The data and the corresponding frequency band are multiplied to obtain the electrical signal.
20. The method according to claim 18 or 19, wherein the method further comprises:

    Receiving first configuration information from the OLT, where the first configuration information includes the frequency band corresponding to the ONU.
21. The method according to claim 18, wherein the performing orthogonality coding on the data to be sent to obtain the electrical signal comprises:

    Determine the codeword corresponding to the ONU;

    The data and the corresponding codeword are multiplied to obtain the electrical signal.
22. The method according to claim 18 or 21, wherein the method further comprises:

    Receiving second configuration information from the OLT, where the second configuration information includes a codeword corresponding to the ONU.
23. The method according to any one of claims 18 to 22, wherein the converting the electrical signal into an optical signal comprises:

    Receiving the first injected light emitted from the OLT;

    Generating a first optical carrier according to the first injected light, the wavelength of the first optical carrier is equal to the wavelength of the first injected light;

    The electrical signal is modulated onto the first optical carrier to obtain the optical signal.
24. The method according to any one of claims 18 to 22, wherein the converting the electrical signal into an optical signal comprises:

    Receiving N second injected lights emitted from the OLT, where N is an integer greater than 1;

    Generating a second optical carrier according to the N second injected lights, the wavelength of the second optical carrier being the same as the wavelength of one second injected light in the N second injected lights;

    The electrical signal is modulated onto the second optical carrier to obtain the optical signal.
25. A data transmission method, characterized in that it is applied to an optical line terminal OLT, and the method includes:

    Receive superimposed optical signals through the optical distribution network ODN;

    Convert the superimposed optical signal into a superimposed electrical signal, the superimposed optical signal is obtained by superimposing M optical signals from M optical network units ONU, and the superimposed electrical signal includes M mutually orthogonal electrical signals, so The M electrical signals correspond to the M optical signals one-to-one, the M ONUs correspond to the M optical signals one-to-one, and the M is an integer greater than 1;

    Perform decoding according to the superimposed electrical signal to obtain data sent by each of the M ONUs.
26. The method according to claim 25, wherein the decoding according to the superimposed electrical signal to obtain the data sent by each ONU of the M ONUs comprises:

    The electrical signals of the corresponding frequency bands in the superimposed electrical signals are respectively allowed to pass, and data sent by each of the M ONUs are obtained. One ONU corresponds to one frequency band, and the frequency bands corresponding to any two ONUs do not overlap each other.
27. The method of claim 25, wherein the decoding according to the superimposed electrical signal comprises:

    The data sent by each ONU is obtained by multiplying and accumulating the codeword corresponding to each ONU among the M ONUs and the superimposed electrical signal. One ONU corresponds to one codeword, and any two codewords are orthogonal to each other.
28. The method according to any one of claims 25 to 27, wherein the method further comprises:

    Respectively emitting the first injected light to each ONU of the M ONUs;

    Wherein, the first injected light is used by the ONU to generate a first optical carrier, the first optical carrier is used to carry an electrical signal of the ONU, and the wavelength of the first optical carrier is the same as that of the first injected light. The wavelength is the same.
29. The method according to any one of claims 25 to 27, wherein the method further comprises:

    Respectively emitting N second injected lights to each of the M ONUs;

    Wherein, the N second injected lights are used for the ONU to generate a second optical carrier, the second optical carrier is used to carry the ONU's electrical signal, and the wavelengths of the N second injected lights are different, so The wavelength of the second optical carrier is the same as the wavelength of one of the N second injected lights, and the N is an integer greater than 1.
30. The method according to any one of claims 25 to 29, wherein the converting the superimposed optical signal into a superimposed electrical signal comprises:

    Receive intrinsic light;

    Performing mixing processing on the intrinsic light and the superimposed light signal to obtain a mixing signal;

    The mixed frequency signal is converted into a superimposed electrical signal.
31. The method according to any one of claims 25 to 29, wherein the converting the superimposed optical signal into a superimposed electrical signal comprises:

    Converting the superimposed light signal into a superimposed current signal;

    The superimposed current signal is converted into a superimposed voltage signal.
32. The method according to any one of claims 25 to 31, wherein the superimposed electrical signal comprises superimposed analog electrical signal and superimposed digital electrical signal;

    The method also includes:

    Receiving the superimposed analog electrical signal from the photoelectric conversion module, and converting the superimposed analog electrical signal into a superimposed digital electrical signal.

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