CN116419099A - A point-to-multipoint optical communication method, device and system - Google Patents

Abstract

The present application provides a point-to-multipoint communication method, device and system. The optical communication method is applied to a point-to-multipoint communication system, and the point-to-multipoint communication system includes a central node and multiple leaf nodes. From the perspective of the central node, the method includes: generating first downlink data and second downlink data; coherently modulating the optical signal according to the first downlink data and the second downlink data to generate a downlink optical signal, the downlink optical signal The first subcarrier of the downlink optical signal carries the first downlink data, and the second subcarrier of the downlink optical signal carries the second downlink data; when the downlink optical signal is sent, the destination node of the first downlink data is the first leaf node, and the destination node of the second downlink data The destination node is the second leaf node. Based on this method, in a multi-rate coexisting P2MP optical communication system, the central node can communicate with leaf nodes of different rates.

Description

A point-to-multipoint optical communication method, device and system

technical field

The present application relates to the field of optical communication, in particular to a point-to-multipoint optical communication method, device and system.

Background technique

Driven by the demand for the Internet of Everything, the number of nodes in the optical communication system continues to increase, and the point-to-multipoint (P2MP) optical communication technology will replace the traditional point-to-point (P2P) optical communication technology , will play an important role in the future scenario of "connecting everything with light". An optical communication system using P2MP optical communication technology is called a P2MP optical communication system or a P2MP optical communication network. A P2MP optical communication system usually includes a central node and multiple leaf nodes. For example, a passive optical network (PON, passive optical network) is a typical P2MP optical communication system. The PON system includes an optical line terminal (optical line termination, OLT) OLT, at least one optical network unit (optical network unit, ONU ) or an optical network terminal (optical network terminal, ONT), wherein the OLT is a central node, and the ONU or ONT is a leaf node.

With the continuous emergence of emerging services, people have higher and higher requirements for service diversity and real-time service, and the network bandwidth and communication rate are also gradually upgraded. In a P2MP optical communication system, the optical communication rates supported by each leaf node may be the same or different. In a multi-rate coexisting P2MP optical communication system, how the central node communicates with each leaf node supporting different rates has become a research hotspot in the industry at present.

Contents of the invention

Embodiments of the present application provide a point-to-multipoint communication method, device, and system. Based on this method, in a multi-rate coexisting P2MP optical communication system, the central node can communicate with leaf nodes of different rates.

In a first aspect, an embodiment of the present application provides an optical communication method, which is applied to a point-to-multipoint communication system, and the point-to-multipoint communication system includes a central node and multiple leaf nodes. From the perspective of the central node, the method includes: generating first downlink data and second downlink data; coherently modulating the optical signal according to the first downlink data and the second downlink data to generate a downlink optical signal, the downlink optical signal The first subcarrier of the downlink optical signal carries the first downlink data, and the second subcarrier of the downlink optical signal carries the second downlink data; when sending the downlink optical signal, the destination node of the first downlink data is the first leaf node, and the destination node of the second downlink data The destination node is the second leaf node.

Based on the method described in the first aspect, the central node in the P2MP system can communicate with multiple leaf nodes with different rates based on different subcarriers of the same downlink wavelength; the central node does not need to integrate multiple optical modules with multiple wavelengths, and also There is no need for wavelength division multiplexing processing, which reduces the engineering cost of the central node; and the central node communicates with multiple leaf nodes of different generations or different rates through frequency division multiplexing without increasing wavelength resources , which increases the system bandwidth.

In some embodiments, the first subcarrier width and the second subcarrier width are the same. That is, regardless of the downlink rates supported by the first leaf node and the second leaf node, the downlink modulation rates corresponding to the first leaf node and the second leaf node are the same. Leaf nodes of different generations or different capabilities can coexist in the same point-to-multipoint communication system, which improves the system's compatibility with diverse devices.

In some implementations, the downlink rate supported by the first leaf node belongs to the same rate level as the rate of the downlink optical signal, and the central node performs coherent modulation on the optical signal according to the first downlink data and the second downlink data, Including that the central node modulates the first downlink data in four dimensions of the downlink optical signal, X polarization I path, X polarization Q path, Y polarization I path and Y polarization Q path.

In some implementation manners, the modulation scheme corresponding to the first downlink data is dual polarization quadrature phase shift keying DP-QPSK, or dual polarization quadrature amplitude modulation DP-QAM.

In some implementations, the downlink rate supported by the second leaf node is lower than the rate of the downlink optical signal, and the central node performs coherent modulation on the optical signal according to the first downlink data and the second downlink data, specifically including: the second downlink The data is redundantly encoded, and the rate of the redundantly encoded second downlink data and the rate of the downlink optical signal belong to the same rate level, and the redundantly encoded second downlink data includes the second downlink data and redundant data; The encoded second downlink data is modulated in four dimensions of the downlink optical signal. Based on the mechanism of redundant coding, the central node can modulate the downlink data corresponding to different generations or leaf nodes supporting different downlink rates into the downlink optical signal of the same wavelength at the same modulation rate. The central node communicates with multiple leaf nodes of different generations or different rates without increasing wavelength resources, which improves system compatibility and bandwidth.

In some implementations, the downlink rate supported by the second leaf node is equal to a quarter of the downlink optical signal rate, and the modulation mode corresponding to the second downlink data is amplitude shift keying ASK or binary phase shift keying BPSK.

In some implementations, the downlink rate supported by the second leaf node is equal to half of the downlink optical signal rate, and the modulation mode corresponding to the second downlink data is quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM).

According to the downlink rate supported by the leaf node, the corresponding modulation mode is selected, which improves the compatibility and flexibility of the system.

In some implementations, the method provided by the embodiment of the present application further includes: the central node obtains the capability information of the first leaf node and the second leaf node, and the capability information includes the rate supported by the leaf node and/or the modulation supported by the leaf node Mode: the central node sends communication parameters corresponding to each first leaf node to the first leaf node and the second leaf node respectively, and the communication parameters include one or more parameters of modulation mode, subcarrier frequency and subcarrier bandwidth. Through the capability negotiation mechanism, the central node can obtain the capability information of each leaf node, and assign corresponding communication parameters to each leaf node, which improves the compatibility and flexibility of the system.

In some implementation manners, during the communication process between the central node and any leaf node, the central node may also initiate or receive a request for renegotiation of communication parameters.

In some embodiments, the point-to-multipoint communication system described in the first aspect is a passive optical network PON, the central node is an optical line terminal OLT, and the leaf nodes are optical network units ONU or optical network terminals ONT.

In the second aspect, the embodiment of the present application provides an optical communication method, which is applied to a point-to-multipoint communication system. The point-to-multipoint communication system includes a central node, a first leaf node, and a second leaf node. From a perspective, the method includes: receiving a downlink optical signal, the downlink optical signal including a plurality of subcarriers; performing coherent demodulation on the first subcarrier of the downlink optical signal to obtain first downlink data. Because the downlink optical signal is divided into multiple subcarriers in the way of frequency division multiplexing, each leaf node corresponds to one of the subcarriers, which improves the system bandwidth.

In some implementation manners, the downlink optical signal includes four dimensions: an X-polarized I path, an X-polarized Q path, a Y-polarized I path, and a Y-polarized Q path.

In some implementations, the downlink rate supported by the first leaf node belongs to the same rate class as the rate of the downlink optical signal, and the first downlink data is modulated in the above four dimensions of the downlink optical signal.

In some implementation manners, the modulation scheme corresponding to the first downlink data is dual polarization quadrature phase shift keying DP-QPSK, or dual polarization quadrature amplitude modulation DP-QAM.

In some implementations, the downlink rate supported by the first leaf node is lower than the rate of the downlink optical signal, and the first downlink data is modulated in 1-3 dimensions of the downlink optical signal.

In some implementations, the downlink rate supported by the first leaf node is equal to a quarter of the downlink optical signal rate, and the modulation mode corresponding to the first downlink data is ASK or BPSK.

In some implementations, the downlink rate supported by the first leaf node is equal to half of the downlink optical signal rate, and the modulation mode corresponding to the first downlink data is quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM).

In some implementations, the method described in the second aspect further includes: the first leaf node sends capability information of the first leaf node to the central node, where the capability information includes the rate supported by the leaf node and/or the modulation mode supported by the leaf node ; The first leaf node receives the communication parameters assigned by the central node to the first leaf node, and the communication parameters include one or more parameters of modulation mode, sub-carrier frequency and sub-carrier bandwidth.

In some implementation manners, during the communication process between the central node and the first leaf node, the first leaf node may also initiate or receive a communication parameter renegotiation request.

In some embodiments, the point-to-multipoint communication system is a passive optical network PON, the central node is an optical line terminal OLT, and the first leaf node is an optical network unit ONU or an optical network terminal ONT.

In a third aspect, the embodiment of the present application provides an optical communication device, including a signal processor, a light source, and a modulator. The optical communication device may specifically be used to implement various method procedures executed by the central node as described in the first aspect. The processor is used to generate the first downlink data and the second downlink data, and the modulator is used to coherently modulate the optical signal output by the light source according to the first downlink data and the second downlink data to generate the downlink optical signal, and the first downlink optical signal The subcarrier carries the first downlink data, the second subcarrier of the downlink optical signal carries the second downlink data; the modulator is also used to send the downlink optical signal, the destination node of the first downlink data is the first leaf node, and the second downlink The destination node of the data is the second leaf node.

In some embodiments, the first subcarrier width and the second subcarrier width are the same.

In some implementations, the downlink rate supported by the first leaf node belongs to the same rate class as the rate of the downlink optical signal, and the modulator is used to modulate the first downlink data in four dimensions of the downlink optical signal, X polarization I path, X polarization Q channel, Y polarization I channel and Y polarization Q channel.

In some implementation manners, the modulation scheme corresponding to the first downlink data is dual polarization quadrature phase shift keying DP-QPSK, or dual polarization quadrature amplitude modulation DP-QAM.

In some implementations, the processor includes a protocol encoding module and an adaptation processing module, the protocol encoding module is used to generate the first downlink data and the second downlink data; when the downlink rate supported by the second leaf node is less than When the rate of the downlink optical signal is determined, the adaptation processing module is used to perform redundant encoding on the second downlink data. The rate of the second downlink data after redundant encoding and the rate of the downlink optical signal belong to the same rate level. The second downlink data includes second downlink data and redundant data; the modulator is used to modulate the redundantly encoded second downlink data in the four dimensions of the downlink optical signal, X polarization I path, X polarization Q path, Y polarization I channel and Y polarization Q channel.

In some implementations, the downlink rate supported by the second leaf node is equal to a quarter of the downlink optical signal rate, and the modulation mode corresponding to the second downlink data is amplitude shift keying ASK or binary phase shift keying BPSK.

In some implementations, the downlink rate supported by the second leaf node is equal to half of the downlink optical signal rate, and the modulation mode corresponding to the second downlink data is quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM).

In some implementations, the processor is further configured to obtain capability information of the first leaf node and the second leaf node, where the capability information includes the rate supported by the leaf node and/or the modulation mode supported by the leaf node; the processor, It is also used to determine the communication parameters of the first leaf node and the second leaf node, where the communication parameters include one or more parameters of modulation mode, sub-carrier frequency and sub-carrier bandwidth.

In some implementations, the processor is further configured to initiate or receive a communication parameter renegotiation request.

In some implementation manners, the optical communication device is an optical line terminal (OLT), and the modulator is a dual-polarization in-phase and quadrature modulator.

In a fourth aspect, the embodiment of the present application provides an optical communication terminal device, including a light source, a demodulator, and a processor. The optical communication terminal device may specifically be used to implement various method procedures performed by the leaf node as described in the second aspect. The demodulator is used to receive the downlink optical signal, and the downlink optical signal includes multiple subcarriers; the light source is used to emit coherent local oscillator light; the demodulator is also used to pair the first subcarrier of the downlink optical signal based on the coherent local oscillator light performing coherent demodulation to obtain first downlink data; a processor configured to process the first downlink data.

In some implementations, the downlink optical signal includes four dimensions: X polarization I path, X polarization Q path, Y polarization I path and Y polarization Q path.

In some embodiments, the downlink rate supported by the optical communication terminal device belongs to the same rate class as the rate of the downlink optical signal, and the demodulator is a four-dimensional signal demodulator, and the demodulator is used to obtain The first downlink data.

In some embodiments, the downlink rate supported by the optical communication terminal device is equal to a quarter of the downlink optical signal rate, and the demodulator is a one-dimensional signal demodulator, and the demodulator is used to obtain the first downlink data.

In some embodiments, the downlink rate supported by the optical communication terminal device is equal to half of the downlink optical signal rate, and the demodulator is a two-dimensional signal demodulator, and the demodulator is used to obtain the Describe the first downlink data.

In some implementations, the processor is further configured to receive communication parameters corresponding to the optical communication terminal device, where the communication parameters include one or more parameters of modulation mode, subcarrier frequency and subcarrier bandwidth.

In some implementations, the processor is further configured to initiate or receive a communication parameter renegotiation request.

In some embodiments, the optical communication terminal device is an optical network unit ONU or an optical network terminal ONT.

In the fifth aspect, the embodiment of the present application provides a chip, including a communication interface and a processor, and the processor is configured to execute instructions, so that the chip implements the method described in the first aspect or the second aspect.

In a sixth aspect, an embodiment of the present application provides a point-to-multipoint communication system, and the point-to-multipoint communication system includes the optical communication device described in the third aspect and the optical communication terminal device described in the fourth aspect.

In a seventh aspect, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a device, the device implements the method as described in the first aspect or the second aspect.

In an eighth aspect, a computer program product including instructions is provided, and when the instructions are executed by a computer, the device implements the method as described in the first aspect or the second aspect.

Description of drawings

FIG. 1 is a schematic diagram of a point-to-multipoint communication system architecture applicable to an embodiment of the present application;

FIG. 2 is a schematic diagram of evolution of a PON system;

FIG. 3 is a schematic diagram of a point-to-multipoint communication solution provided by an embodiment of the present application;

FIG. 4 is a schematic structural diagram of a central node provided by an embodiment of the present application;

Figure 4a is a schematic structural diagram of a dual-polarization in-phase quadrature modulator;

FIG. 5 is a schematic structural diagram of a leaf node provided by an embodiment of the present application;

FIG. 6 is a schematic structural diagram of a leaf node one-dimensional signal demodulator provided in an embodiment of the present application;

FIG. 7a is a schematic structural diagram of a leaf node two-dimensional signal demodulator provided in an embodiment of the present application;

Fig. 7b is a schematic structural diagram of another leaf node two-dimensional signal demodulator provided in the embodiment of the present application;

FIG. 8 is a schematic structural diagram of a leaf node four-dimensional signal demodulator provided in an embodiment of the present application;

FIG. 9 is a schematic diagram of another point-to-multipoint communication solution provided by the embodiment of the present application;

FIG. 10 is a schematic diagram of another point-to-multipoint communication solution provided by the embodiment of the present application;

FIG. 11 is a schematic flowchart of a communication parameter negotiation method provided in an embodiment of the present application;

FIG. 12 is a schematic flowchart of a communication parameter renegotiation method provided by an embodiment of the present application;

FIG. 13 is a schematic flowchart of another communication parameter renegotiation method provided by the embodiment of the present application;

FIG. 14 is a schematic diagram of a metropolitan ring network used in the embodiment of the present application.

FIG. 15 is a schematic diagram of a chip provided by an embodiment of the present application.

Detailed ways

The embodiment of the present application relates to a P2MP network or a P2MP system, that is, a point-to-multipoint communication network or communication system. As shown in FIG. 1 , the network or system includes a central node 110 and multiple leaf nodes 131-133. It should be noted that the connection between the central node 110 and the leaf nodes 131-133 shown in FIG. 1 is a logical illustration, and the central node 110 can be connected to the leaf nodes 131-133 through various physical connection methods or networking methods; The central node 110 can be connected to each leaf node through a plurality of local ports, or can be connected to an optical splitting device through a local port, and then the optical splitting device is connected to a plurality of leaf nodes 131-133.

The embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings.

With the continuous evolution of optical communication technology, various intergenerational optical communication technologies have emerged. Different generations of optical communication technologies can achieve different communication rates, and the wavelengths or bands selected for communication are often different. When the optical communication technologies supported by multiple leaf nodes in a P2MP system are different, in order to ensure the compatibility of the system with old and new technologies, the central node often needs to integrate a variety of optical transceiver devices to support receiving and receiving at different wavelengths and rates. emission. For example, among various PON communication technical standards formulated by the International Telecommunication Union (ITU), Gigabit PON (gigabit-capable PON, GPON) technology has a downlink rate of approximately 2.5Gbps and a downlink communication wavelength of 1480-1500nm; 10 gigabit per second PON (10gigabit per second PON, XG-PON) technology, the downlink rate is roughly 10Gbps, downlink communication wavelength is 1575-1580nm; 50 gigabit per second PON (50gigabit per second PON, 50G-PON) technology, The downlink rate is roughly 50Gbps, and the downlink communication wavelength is 1340–1344nm. It should be noted that the downlink mentioned in this application refers to the communication from the central node 110 to the leaf nodes 131-133; the uplink refers to the communication from the leaf nodes 131-133 to the central node 110.

In the PON system shown in FIG. 2 , OLT 210 is a central node, ONUs 231 , 232 , and 233 are leaf nodes, and OLT 210 communicates with multiple leaf nodes through an optical distribution network 220 . Assuming that in the initial stage of network deployment, ONUs 231, 232, and 233 are devices supporting GPON, the optical module of the central node OLT 210 only needs to include a 1490nm transmitter. With the evolution of technology and the upgrade of the network, the equipment supporting XG-PON is deployed. Assuming that ONU 233 is upgraded to ONU 234 supporting XG-PON, that is, there are equipment ONU 231 and 232 supporting GPON and ONU 232 supporting XG-PON in the network. Equipment ONU 234; Corresponding to the upgrade of the ONU side, the OLT 210 also needs to be upgraded. The optical module of the upgraded OLT 211 includes two transmitters, and the corresponding wavelengths of the two transmitters are 1490nm (GPON) and 1577nm (XG -PON), the two wavelengths of light emitted by the OLT 211 are output to the external optical fiber through the wavelength multiplexer; on the ONU side, the GPON optical module selects the 1490nm wavelength for reception through the filter, and the XG-PON optical module selects the 1577nm wavelength for reception.

With the continuous evolution of communication technology generations, there may be a scenario where multiple generations of technologies coexist, and the central node needs to integrate more optical transceiver devices. Therefore, in the technology evolution mode based on wavelength extension or wavelength multiplexing, with the continuous update and evolution of technology, the equipment cost, compatibility cost, upgrade cost and maintenance cost of the P2MP system will gradually increase.

This application proposes a new optical communication technology evolution model and a new multi-generational optical communication technology coexistence mechanism to achieve the coexistence of different generations or leaf nodes supporting different rates under the same transmission wavelength.

As shown in Figure 3, it is assumed that a P2MP system includes a central node OLT and multiple leaf nodes ONU1, ONU2 and ONU3; wherein the rate supported by ONU1 is 1Gb/s, the rate supported by ONU2 is 2Gb/s, and the rate supported by ONU3 is 4Gb/s. In the downlink communication direction, the OLT transmits data to ONU1, ONU2, and ONU3 respectively at the same downlink transmission rate in optical signals of the same wavelength and based on frequency division multiplexing. For the convenience of description, OLT The data sent to the ONU is referred to as downlink ONU data; assuming that the OLT downlink transmission rate is 4Gb/s, that is, the downlink ONU1 data rate, downlink ONU2 data rate and downlink ONU3 data rate transmitted on the optical fiber line from OLT to ONU are all 4Gb/s. In the time domain, the OLT uses coherent modulation to carry the data of each downlink ONU in the downlink optical signal of the same wavelength; in the frequency domain, the OLT carries the data of each downlink ONU on different subcarriers, and the downlink ONU1 data occupies a subcarrier 1. Downlink ONU2 data occupies subcarrier 2, and downlink ONU3 data occupies subcarrier 3. The spectrum width of each subcarrier is the same, that is, the rate of downlink ONU1 data, the rate of downlink ONU2 data and the rate of downlink ONU3 data are the same. It should be noted that the rates described in the embodiments of the present application are the same, including that the rates are substantially the same or belong to the same rate level.

FIG. 4 is a schematic diagram of a possible central node structure provided by the embodiment of the present application. The OLT in FIG. 3 can adopt the structure in FIG. 4 to perform coherent modulation on the downlink optical signal. The central node includes a signal processor 410 , a modulator 420 and a light source 430 . Exemplarily, the light source 430 can be a laser; the modulator 420 can include a polarization splitter, a polarization combiner, and a Mach-Zehnder modulator (Mach-Zehnder modulator, MZM), as shown in Figure 4a. Intermodulator; signal processor 410 may include a protocol encoding module and an adaptation processing module as shown in FIG. 4 . A digital-to-analog converter DAC may also be provided between the signal processor 410 and the modulator 420 . In the downlink transmission direction, the signal processor 410 is used to generate electrical signals of service data, the light source 430 is used to generate optical signals, the modulator 420 carries the electrical signals generated by the signal processor 410 into the optical signals generated by the light source 430, and transmits Optical signals are sent to one or more leaf nodes. The protocol encoding module in the signal processor 410 is used to encode the data to be sent to each leaf node according to the frame format defined by the communication protocol. For example, the protocol encoding module may be a target Media Access Control (MAC) chip. In conjunction with the embodiment shown in Figure 3, the protocol encoding module outputs 1Gb/s data to be sent to ONU1, 2Gb/s data to be sent to ONU2, and 4Gb/s data to be sent to ONU3. The adaptation processing module in the signal processor 410 is used for carrying out adaptive coding, to adapt the rate and the downlink transmission rate supported by the ONU, such as the adaptation processing module can be an optical digital signal processor (optical digital signal processor, oDSP) . Those skilled in the art can understand that the functions corresponding to the protocol encoding module and the adaptation processing module can also be integrated in one chip. Since the data rate output by the OLT internal protocol encoding module to be sent to ONU1 is 1Gb/s, the adaptation processing module needs to perform 4 times redundant encoding on the 1Gb/s data output by the protocol encoding module to match the downlink of the OLT Transmission rate. For convenience of description, in the embodiment of the present application, the data before redundant encoding is referred to as effective downlink ONU data. Effective downlink ONU1 data of 1Gb/s, after 4 times redundant coding, becomes downlink ONU1 data with a rate of 4Gb/s. It should be noted that this application does not limit the encoding algorithm of redundant encoding, for example, invalid data can be filled, and valid downlink ONU data can also be copied. Similarly, the effective downlink ONU2 data with a rate of 2Gb/s also needs to be converted into downlink ONU2 data with a rate of 4Gb/s after the redundant coding of the adaptive processing module; and because the rate of the effective downlink ONU3 data has been compared with that of the OLT The downlink transmission rate is the same, both are 4Gb/s, so the effective downlink ONU3 data no longer needs redundant coding processing. It should be noted that in FIG. 4 , the adaptation processing module 1 and the adaptation processing module 2 are shown respectively, but those skilled in the art should understand that the adaptation processing module 1 and the adaptation processing module 2 may be independent modules , may also be an unification module, or a sub-module integrated in the protocol encoding module. It should also be noted that the branch of effective downlink ONU3 data in Figure 4 does not reflect the adaptation processing module, but those skilled in the art should understand that although the effective downlink ONU3 data does not require additional redundant coding, due to the scheme Consistency of implementation, in a possible implementation mode, valid downlink ONU3 data, valid downlink ONU1 data, and valid downlink ONU2 data are all used as the input of the adaptation processing module. Perform transparent transmission processing, that is, the adaptation processing module does not perform redundant coding on valid downlink ONU3 data. Downstream ONU1 data, downlink ONU2 data and downlink ONU3 data combined downlink data, including X-1, X-Q, Y-I, Y-Q four parts, the rate of each part is 1/4 of the downlink data rate (4Gb/s) One (1Gb/s). The dual-polarization in-phase quadrature modulator is used to modulate the downlink optical signal with multiple transmission dimensions or multi-dimensionality; specifically, the four parts X-1, X-Q, Y-I, and Y-Q of the downlink data are respectively modulated on the four parts of the downlink optical wave signal. Dimensions (X polarization I channel, X polarization Q channel, Y polarization I channel and Y polarization Q channel), the rate of each dimension is 1Gb/s. It should be noted that since the effective downlink ONU1 data is 1Gb/s, the effective downlink ONU1 data only needs to be modulated in one dimension of the downlink light wave, or in other words, the transmission rate of one dimension of the downlink light wave can meet the requirements of the effective downlink ONU1 data. rate requirements; similarly, the transmission rate of the two dimensions of the downlink optical wave can meet the requirements of the effective downlink ONU2 data rate. Therefore, according to the effective downstream data rate, in FIG. 3 , the downstream ONU1 data is also called a one-dimensional signal, the downstream ONU2 data is also called a two-dimensional signal, and the downstream ONU3 data is also called a four-dimensional signal.

Fig. 4a is a schematic structural diagram of a dual-polarization in-phase quadrature modulator provided by an embodiment of the present application. The dual-polarization in-phase quadrature modulator in Fig. 4 can adopt the structure shown in Fig. 4a. The dual-polarization in-phase quadrature modulator shown in Fig. 4a includes a polarization splitter, a Mach Zehnder Modulator (MZM) and a polarization combiner. Light waves emitted by a light source (such as a laser) are divided into X-polarized waves and Y-polarized waves by a polarization splitter. The X-1 part of the downlink data is converted into an analog signal by a digital-to-analog converter (DAC), modulated by MZM1, and modulated on the X polarization I channel of the downlink light wave; the X-Q part of the downlink data After being converted into an analog signal by DAC, modulated by MZM2 and subjected to a 90-degree phase shift, it is modulated on the X polarization Q path of the downlink light wave; the Y-1 part of the downlink data is converted into an analog signal by DAC, and modulated by MZM3. It is modulated on the Y polarization I path of the downlink light wave; the Y-Q part of the downlink data is converted into an analog signal by DAC, modulated by MZM4 and phase-shifted by 90 degrees, and then modulated on the Y polarization Q path of the downlink light wave.

The OLT shown in Figure 3 modulates the downlink data in the four dimensions of the downlink light wave, and the ONU at the receiving end chooses to receive part or all of the four-dimensional data modulated in the downlink light wave according to its own capabilities.

FIG. 5 is a schematic structural diagram of a leaf node provided by an embodiment of the present application. As shown in FIG. 5 , a leaf node 500 includes a demodulator 510 , a light source 520 and a signal processor 530 . The leaf node adopts the mode of coherent demodulation, the light emitted by the light source 520 is used as the local oscillator light, the demodulator 510 performs coherent demodulation on the received downlink optical signal, and the demodulated signal is processed by the signal processor. The demodulator 510 may specifically be a one-dimensional signal demodulator as shown in FIG. 6, or a two-dimensional signal demodulator as shown in FIG. 7, or a four-dimensional signal demodulator as shown in FIG. 8, or other structures the demodulator. A leaf node may also include multiple types of demodulators. The ONU1 in FIG. 3 can adopt the structure of a one-dimensional signal demodulator as shown in 6, and adopt coherent detection to receive and demodulate the data of any dimension in the subcarrier corresponding to the downlink optical signal ONU1. In FIG. 6 , a signal output by a balanced photodetector (balanced photodetector, BPD) corresponds to data of one dimension in a downlink optical signal. The ONU2 in Figure 3 can adopt the structure of a two-dimensional signal demodulator as shown in Figure 7a or Figure 7b, and adopt a coherent detection method to receive and demodulate any two orthogonal dimensions of the downlink optical signal ONU2 corresponding to the subcarrier data. In Figure 7a or Figure 7b, the signals output by the two BPDs correspond to the data of two orthogonal dimensions in the downlink optical signal, such as X polarization I path and X polarization Q path, or Y polarization I path and Y polarization Q path, Either X polarization I path and Y polarization I path, or X polarization Q path and Y polarization Q path. The ONU3 in FIG. 3 can adopt the structure of the four-dimensional signal demodulator shown in FIG. 8 to receive and demodulate the four-dimensional data in the subcarrier corresponding to the downlink optical signal ONU3.

It should be noted that, the above embodiment does not limit the specific modulation mode of optical signal modulation, and specifically, one or more attributes such as amplitude, frequency, phase, and polarization state of light may be modulated. Common modulation methods include amplitude modulation, which uses different amplitudes of a carrier to represent different digital symbols to transmit a set of code streams; frequency modulation, which uses carriers of different frequencies to represent different digital symbols to transmit a set of code streams ; Phase modulation, by changing the phase value of a carrier to represent different digital symbols, to transmit a set of code streams; polarization modulation, modulate and transmit a set of code streams in a certain polarization direction of the light wave. In the embodiment described above, for the downlink ONU1 data, modulation methods such as amplitude shift keying (amplitude shiftkeying, ASK) or binary phase shift keying (binary phase shift keying, BPSK) can be used, and the effective downlink ONU1 data The modulation is on each transmission dimension of the downlink optical wave; for the downlink ONU2 data, you can use quadrature phase shift keying (quadrature phase shift keying, QPSK), or quadrature amplitude modulation (quadrature amplitude modulation, QAM) and other modulation methods, which will effectively downlink ONU2 data is modulated on at least two transmission dimensions of downlink light waves; for downlink ONU3 data, dual-polarization quadrature phase-shift keying (dual-polarization QPSK, DP-QPSK) or dual-polarization quadrature amplitude modulation (dual- Polarization QAM, DP-QAM) and other modulation methods, modulate the downlink ONU3 data on the four transmission dimensions of the downlink optical wave.

According to the solution shown in Figure 3-Figure 8, the OLT can communicate with multiple ONUs with different rates based on different subcarriers of the same downlink wavelength; the OLT does not need to integrate multiple optical modules with multiple wavelengths, nor does it need to perform wavelength division The multiplexing processing reduces the engineering cost of the OLT; and the OLT communicates with multiple ONUs of different generations or different rates through frequency division multiplexing without increasing wavelength resources, which improves the system bandwidth; ONUs with actual or different capabilities can coexist in the same PON system, which improves the system's compatibility with diverse devices.

Those skilled in the art should understand that the network element type, downlink transmission rate, modulation mode, ONU quantity and ONU capability and other information in the above embodiments are just examples and do not constitute any limitation to the protection scope of the present application.

In a possible embodiment, the solution proposed in this application is also applicable to the P2MP system shown in FIG. 9 . In this system, the rates supported by the leaf nodes (ONU1 931, ONU2 932 and ONU3 933) are the same, all of which are 1Gb/s. In this case, after the OLT 910 performs adaptive coding on the effective downlink data of each leaf node ( For example, 4-fold redundant coding is performed), and the downlink data with a rate of 4Gb/s after adaptive coding is modulated on the four transmission dimensions of the downlink light wave. Each ONU can use the demodulator shown in 6 to receive data of any dimension on the subcarrier corresponding to the downlink optical wave.

In another possible embodiment, the solution proposed in this application is also applicable to the P2MP2 system shown in FIG. 10 . In this system, the rate supported by ONU1 is 2Gb/s, the rate supported by ONU2 is 4Gb/s, the rate supported by ONU3 is 8Gb/s, and the downlink transmission rate between the central node and leaf nodes is 8Gb/s.

In the P2MP system provided by the embodiment of this application, leaf nodes with multiple generations or multiple capabilities coexist, the central node needs to perform data encoding and modulation according to the capabilities of each leaf node, and the leaf nodes also need to perform data encoding and modulation according to their corresponding subcarriers. Perform data reception and demodulation. Therefore, in order to realize frequency-division multiplexing-based communication between the central node and multi-generational leaf nodes under a single wavelength, communication parameters need to be negotiated between the central node and the leaf nodes.

FIG. 11 is a schematic flowchart of a method for negotiating communication parameters between a central node and a leaf node provided in an embodiment of the present application.

Step 1101: the central node sends a first message to the leaf node, which carries modulation mode indication information, and the modulation mode indication information is used to indicate the modulation mode that the leaf node should use in the registration phase. The first message may be registration indication information sent by the central node to the leaf nodes, or other messages, which are not limited in this application. For example, in a PON system, the OLT can broadcast a discovery discovery message to an unregistered ONU, and the discovery message instructs the ONU to use modulation mode 1 for communication in the registration phase. It should be noted that the 1101 message is not necessary, and the central node and leaf nodes in a P2MP system can also use a default modulation mode to communicate in the registration phase.

Step 1102: the leaf node sends a registration request message to the central node, and the registration request message is modulated and demodulated using modulation mode 1 indicated or agreed by the central node. In addition, the leaf node also sends the capability set supported by the leaf node to the central node through the second message. The capability set supported by the leaf node includes the protocol type supported by the leaf node, the rate supported by the leaf node, and the modulation mode supported by the leaf node. or a variety of information; the modulation methods include ASK, BPSK, QPSK, QAM, DP-QPSK, DP-QAM, etc. The second message may be a registration request message or other messages, which are not limited in this application.

Step 1103: the central node sends communication parameters to the leaf nodes through the third message, and the communication parameters include one or more parameters such as modulation mode, subcarrier frequency, and subcarrier bandwidth. In an optional implementation, the central node comprehensively considers its own capabilities and the conditions of other devices in the system, and determines the communication parameters corresponding to each registered leaf node to ensure that the central node can use the same wavelength. Mode to communicate with the leaf nodes in the system. The third message may be a registration success indication message, or other messages, which are not limited in this application.

Step 1104: the central node and the leaf nodes use communication parameters to perform data modulation and demodulation.

After the central node and the leaf nodes negotiate to determine the first set of communication parameters, the central node and the leaf nodes can further negotiate to obtain a second set of communication parameters to replace the first set of communication parameters. The communication parameter renegotiation process can be initiated by the central node or by the leaf node.

FIG. 12 is a schematic flowchart of a method for initiating communication parameter renegotiation by a central node provided in an embodiment of the present application.

Step 1201: The central node initiates the communication parameter renegotiation process. There are many ways for the central node to initiate the renegotiation process. For example, the central node sends a renegotiation request message to the leaf node, instructing the leaf node to report a certain capability or certain capability supported by the leaf node. or the central node instructs the leaf node to report a certain capability or a certain capability set supported by the leaf node through an indication cell or indication information in any downlink message sent to the leaf node.

Step 1202: the leaf node reports a certain capability or a certain capability set supported by the leaf node according to the instruction of the central node.

Step 1203: the central node sends communication parameters to the leaf nodes. The communication parameters may be partially or completely the same as the previous communication parameters, or completely different. For example, assuming that the central node is the OLT in Figure 9, and the leaf node is ONU3 933 in Figure 9, then after the central node and the leaf node negotiate according to Figure 11, the central node determines that the modulation method corresponding to the leaf node ONU3 933 is ASK or BPSK ; If the ONU3 933 in Figure 9 is upgraded to the ONU3 333 in Figure 3, due to the increase in the ONU3 rate, the central node needs to modulate the downlink ONU3 data on the 4 transmission dimensions of the downlink optical wave, therefore, the central node and the leaf node ONU3 After 933 performs renegotiation according to FIG. 12 , the central node determines that the modulation mode corresponding to the leaf node ONU3 333 is DP-QAM or DP-QPSK.

FIG. 13 is a schematic flowchart of a method for initiating communication parameter renegotiation by a leaf node provided in an embodiment of the present application. Different from the flow shown in FIG. 12 , in the flow shown in FIG. 13 , the leaf node actively reports to the central node some or all of the capabilities it supports. Steps 1301 to 1303 respectively correspond to steps 1202 to 1204 in FIG. 12 , and will not be repeated here.

When the P2MP system changes, such as new leaf nodes, or some leaf nodes are upgraded, the central node or leaf nodes can initiate a communication parameter renegotiation process according to the method shown in Figure 12 or Figure 13 to ensure that the central node It can use the same wavelength to communicate with the leaf nodes in the system based on the mode of frequency division multiplexing.

It should be noted that the leaf node shown in Figure 11-Figure 13 is only a leaf node in the P2MP system, and the central node also needs to negotiate communication parameters with other leaf nodes in the P2MP system, the negotiation process or the re-negotiation process Similar to the processes shown in Fig. 11-Fig. 13, details are not repeated here. In addition, the message names shown in FIG. 11-FIG. 13 are only examples, and do not limit the protection scope of the present application.

The embodiment of the present application also provides a chip, as shown in FIG. 15 , which is a schematic diagram of a chip 1500 provided in the present application. The chip 1500 includes a processor 1510 and a communication interface 1530 . The processor 1510 is configured to execute instructions, so that the method of the central node or the leaf node in the above method embodiments is executed. The chip 1500 may also include a memory 1120, the processor 1110 is coupled to the memory 1120, and the memory 1120 is used for storing computer programs or instructions or and/or data.

It should also be noted that, for the convenience of understanding, some embodiments of this application take the PON system as an example to describe the technical solutions. Those skilled in the art should understand that the technical solutions proposed in this application are also applicable to other P2MP networks Or systems, such as metropolitan ring network, passive optical LAN (POL), industrial optical network, vehicle optical network, Internet of Things, etc. In the metropolitan area ring network shown in FIG. 14 , a central office (Central Office, CO) is a central node, and a sub central office (Sub Central Office, SubCO) is a leaf node. In the industrial optical network scenario, the central node and leaf nodes can be located in the industrial manufacturing workshop. In the vehicle optical network scenario, the central node and the leaf nodes can be set in the vehicle, the central node can be the vehicle interface unit (vehicle interface unit, VIU), and the leaf nodes can be the mobile data center (MDC), vehicle dynamic control (vehicle dynamic control , VDC) or cockpit data center (Cockpit datacenter, CDC), etc. The technical solution proposed in this application is also applicable to P2MP networks or systems such as optical backbone transmission network, data center optical transmission, short-distance optical interconnection, and wireless service fronthaul/backhaul.

Claims (40)

1. An optical communication method, applied to a point-to-multipoint communication system, said point-to-multipoint communication system comprising a central node, a first leaf node and a second leaf node, characterized in that, The central node generates first downlink data and second downlink data; The central node coherently modulates the optical signal according to the first downlink data and the second downlink data to generate a downlink optical signal, the first subcarrier of the downlink optical signal carries the first downlink data, The second subcarrier of the downlink optical signal carries the second downlink data; The central node sends the downlink optical signal, the destination node of the first downlink data is a first leaf node, and the destination node of the second downlink data is a second leaf node. 2. The method according to claim 1, wherein the first subcarrier width and the second subcarrier width are the same. 3. The method according to claim 1 or 2, wherein the downlink rate supported by the first leaf node belongs to the same rate class as the rate of the downlink optical signal, and the central node according to the first downlink rate Data and second downlink data coherently modulate the optical signal, including the central node modulating the first downlink data in the four dimensions of the downlink optical signal, X polarization I path, X polarization Q path, Y polarization I channel and Y polarization Q channel. 4. The method according to claim 3, wherein the modulation scheme corresponding to the first downlink data is dual polarization quadrature phase shift keying (DP-QPSK), or dual polarization quadrature amplitude modulation (DP-QAM). 5. The method according to any one of claims 2-4, wherein the downlink rate supported by the second leaf node is lower than the rate of the downlink optical signal, and the central node according to the first downlink data and the second 2. Downlink data coherently modulates the optical signal, including, The central node performs redundant coding on the second downlink data, the rate of the redundantly coded second downlink data and the rate of the downlink optical signal belong to the same rate level, and the redundantly coded second The downlink data includes the second downlink data and redundant data; The central node modulates the redundantly encoded second downlink data in four dimensions of the downlink optical signal. 6. The method according to claim 5, wherein the downlink rate supported by the second leaf node is equal to a quarter of the rate of the downlink optical signal, and the modulation method corresponding to the second downlink data is amplitude Shift Keying ASK, or Binary Phase Shift Keying BPSK. 7. The method according to claim 5, wherein the downlink rate supported by the second leaf node is equal to half of the downlink optical signal rate, and the modulation mode corresponding to the second downlink data is positive Cross Phase Shift Keying QPSK, or Quadrature Amplitude Modulation QAM. 8. The method according to any one of claims 1-7, characterized in that the method further comprises, The central node acquires capability information of the first leaf node and the second leaf node, where the capability information includes the rate supported by the leaf node and/or the modulation mode supported by the leaf node; The central node sends communication parameters corresponding to each first leaf node to the first leaf node and the second leaf node respectively, and the communication parameters include modulation mode, one of subcarrier frequency and subcarrier bandwidth or Various parameters. 9. The method according to any one of claims 1-8, characterized in that, the method further comprises, during the communication process between the central node and the any leaf node, the central node initiates or receives communication parameters Renegotiate the request. 10. The method according to any one of claims 1-9, wherein the point-to-multipoint communication system is a passive optical network (PON), the central node is an optical line terminal (OLT), and any leaf node It is an optical network unit ONU or an optical network terminal ONT. 11. An optical communication method, applied to a point-to-multipoint communication system, the point-to-multipoint communication system comprising a central node, a first leaf node and a second leaf node, characterized in that, The first leaf node receives a downlink optical signal, and the downlink optical signal includes a plurality of subcarriers; The first leaf node performs coherent demodulation on the first subcarrier of the downlink optical signal to obtain first downlink data. 12 . The method according to claim 11 , wherein the downlink optical signal includes four dimensions: X polarization I path, X polarization Q path, Y polarization I path and Y polarization Q path. 13. The method according to claim 12, wherein the downlink rate supported by the first leaf node belongs to the same rate class as the rate of the downlink optical signal, and the first downlink data is modulated at the Describe the four dimensions of the downlink optical signal. 14. The method according to claim 13, wherein the modulation scheme corresponding to the first downlink data is dual polarization quadrature phase shift keying (DP-QPSK) or dual polarization quadrature amplitude modulation (DP-QAM). 15. The method according to claim 12, wherein the downlink rate supported by the first leaf node is lower than the rate of the downlink optical signal, and the first downlink data is modulated at the rate of the downlink optical signal 1-3 dimensions among them. 16. The method according to claim 15, wherein the downlink rate supported by the first leaf node is equal to a quarter of the downlink optical signal rate, and the modulation method corresponding to the first downlink data is Amplitude Shift Keying ASK, or Binary Phase Shift Keying BPSK. 17. The method according to claim 15, wherein the downlink rate supported by the first leaf node is equal to half of the downlink optical signal rate, and the modulation method corresponding to the first downlink data is Quadrature Phase Shift Keying QPSK, or Quadrature Amplitude Modulation QAM. 18. The method according to any one of claims 11-17, further comprising, The first leaf node sends capability information of the first leaf node to the central node, where the capability information includes the rate supported by the leaf node and/or the modulation mode supported by the leaf node; The first leaf node receives communication parameters corresponding to the first leaf node, where the communication parameters include one or more parameters of modulation mode, subcarrier frequency, and subcarrier bandwidth. 19. The method according to any one of claims 11-18, further comprising, during the communication process between the central node and the first leaf node, the first leaf node initiates or receives a communication Parameter renegotiation request. 20. The method according to any one of claims 11-19, wherein the point-to-multipoint communication system is a passive optical network (PON), the central node is an optical line terminal (OLT), and the first leaf node It is an optical network unit ONU or an optical network terminal ONT. 21. A chip, comprising a communication interface and a processor, the processor is configured to execute instructions, so that the chip implements the method according to any one of claims 1-10. 22. An optical communication device, comprising a signal processor, a light source and a modulator, The processor is configured to generate first downlink data and second downlink data, The modulator is configured to coherently modulate the optical signal output by the light source according to the first downlink data and the second downlink data to generate a downlink optical signal, where the first subcarrier of the downlink optical signal carries the the first downlink data, the second subcarrier of the downlink optical signal carries the second downlink data; The modulator is further configured to send the downlink optical signal, the destination node of the first downlink data is a first leaf node, and the destination node of the second downlink data is a second leaf node. 23. The apparatus according to claim 22, wherein the first subcarrier width and the second subcarrier width are the same. 24. The device according to any one of claims 22-23, wherein the downlink rate supported by the first leaf node belongs to the same rate class as the rate of the downlink optical signal, and the modulator is used to The first downlink data is modulated in four dimensions of the downlink optical signal, X polarization I path, X polarization Q path, Y polarization I path and Y polarization Q path. 25. The method according to claim 24, wherein the modulation scheme corresponding to the first downlink data is dual polarization quadrature phase shift keying (DP-QPSK), or dual polarization quadrature amplitude modulation (DP-QAM). 26. The device according to any one of claims 23-25, wherein the processor includes a protocol encoding module and an adaptation processing module, The protocol coding module is used to generate the first downlink data and the second downlink data; When the downlink rate supported by the second leaf node is less than the rate of the downlink optical signal, the adaptation processing module is configured to perform redundant encoding on the second downlink data, and the redundantly encoded second downlink data The rate of the downlink optical signal belongs to the same rate level as the rate of the downlink optical signal, and the redundantly encoded second downlink data includes the second downlink data and redundant data; The modulator is used to modulate the redundantly coded second downlink data in four dimensions of the downlink optical signal, X polarization I path, X polarization Q path, Y polarization I path and Y polarization Q path. 27. The device according to claim 26, wherein the downlink rate supported by the second leaf node is equal to a quarter of the rate of the downlink optical signal, and the modulation method corresponding to the second downlink data is amplitude Shift Keying ASK, or Binary Phase Shift Keying BPSK. 28. The device according to claim 26, wherein the downlink rate supported by the second leaf node is equal to half of the downlink optical signal rate, and the modulation mode corresponding to the second downlink data is positive Cross Phase Shift Keying QPSK, or Quadrature Amplitude Modulation QAM. 29. The device according to any one of claims 22-28, characterized in that, The processor is further configured to acquire capability information of the first leaf node and the second leaf node, where the capability information includes a rate supported by the leaf node and/or a modulation mode supported by the leaf node; The processor is further configured to determine communication parameters of the first leaf node and the second leaf node, where the communication parameters include one or more parameters of modulation mode, subcarrier frequency and subcarrier bandwidth. 30. The device according to any one of claims 22-29, wherein the processor is further configured to initiate or receive a communication parameter renegotiation request. 31. The device according to any one of claims 22-30, wherein the optical communication device is an optical line terminal (OLT), and the modulator is a dual-polarization in-phase quadrature modulator. 32. A chip, comprising a communication interface and a processor, the processor is configured to execute instructions, so that the chip implements the method according to any one of claims 11-20. 33. An optical communication terminal device, comprising a light source, a demodulator and a processor, The demodulator is configured to receive a downlink optical signal, and the downlink optical signal includes a plurality of subcarriers; The light source is used to emit coherent local oscillator light; The demodulator is further configured to coherently demodulate the first subcarrier of the downlink optical signal based on the coherent local oscillator light to obtain first downlink data; The processor is configured to process the first downlink data. 34. The optical communication terminal device according to claim 33, wherein the downlink optical signal includes four dimensions: X polarization I path, X polarization Q path, Y polarization I path and Y polarization Q path. 35. The optical communication terminal device according to claim 34, wherein the downlink rate supported by the optical communication terminal device belongs to the same rate level as the rate of the downlink optical signal, and the demodulator is a four-dimensional signal A demodulator, configured to obtain the first downlink data from the four dimensions of the downlink optical signal respectively. 36. The optical communication terminal device according to claim 34, wherein the downlink rate supported by the optical communication terminal device is equal to a quarter of the rate of the downlink optical signal, and the demodulator is a one-dimensional signal A demodulator, configured to obtain the first downlink data from one dimension of the downlink optical signal. 37. The optical communication terminal device according to claim 34, wherein the downlink rate supported by the optical communication terminal device is equal to half of the rate of the downlink optical signal, and the demodulator is a two-dimensional signal A demodulator, configured to obtain the first downlink data from two dimensions of the downlink optical signal. 38. The optical communication terminal device according to any one of claims 33-37, characterized in that, The processor is further configured to receive communication parameters corresponding to the optical communication terminal device, where the communication parameters include one or more parameters of modulation mode, subcarrier frequency and subcarrier bandwidth. 39. The optical communication terminal device according to any one of claims 33-38, wherein the processor is further configured to initiate or receive a communication parameter renegotiation request. 40. The optical communication terminal device according to any one of claims 33-39, wherein the optical communication terminal device is an optical network unit (ONU) or an optical network terminal (ONT).

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