Method and device for carrying out ONU distance measurement by utilizing wavelength dispersion difference

Abstract

The invention relates to the technical field of optical communication low time delay, in particular to a method and a device for carrying out ONU (Optical Network Unit) ranging by utilizing wavelength dispersion difference. Calculating a proportionality coefficient beta lambda1 lambda2 according to a signal transmission time difference delta t3 caused by dispersion of an initial online ONU and a distance L measured by a PON standard ranging process; and the subsequent online ONU calculates the distance of the subsequent online ONU through the proportionality coefficient beta lambda1 and lambda2 and the signal transmission time difference delta t3 caused by dispersion. According to the method, the device and the system, the characteristic of difference of arrival time of downlink data caused by large difference of different downlink wavelengths and large dispersion difference of different intergenerational PONs is fully utilized, and distance measurement of the ONU is realized, so that silent window avoidance of the TDM PONs is carried out.

Description

Technical Field

[0001] This disclosure relates to the field of low-latency optical communication technology, and in particular to a method and apparatus for ONU ranging using wavelength dispersion differences. Background Technology

[0002] Passive Optical Network (PON) technology is a point-to-multipoint fiber optic access technology, consisting of an OLT at the central office, ONUs at the user end, and an ODN. Traditional TDM PON systems use broadcast technology for downlink data flow and TDMA technology for uplink data flow to address the multiplexing problem of signals in each direction for multiple users. In a TDM PON system, when a new Optical Network Unit (ONU) is added to the network, it needs to undergo activation and ranging processes to be discovered and managed by the Optical Line Terminal (OLT). Without special handling, the activation and ranging processes may conflict with normal uplink data transmission. To avoid collisions, the traditional approach is for the OLT to suspend all bandwidth allocation to the ONU. During this period, the data that the ONU is about to send is internally buffered and not transmitted, while the newly added ONU performs activation and ranging. After this period, the buffered data is transmitted; this process is called a silent window. According to the protocol standard ITU G.984, a silent window typically causes network transmission to experience delays and jitter exceeding 250 microseconds.

[0003] Emerging services such as industrial PON and immersive interactive XR place new demands on network latency and jitter. To reduce network latency and jitter, the ITU G.9804.2 standard proposes a dedicated activation wavelength to eliminate silent windows. The OLT performs activation and ranging processes by adding a new uplink wavelength or utilizing the uplink wavelength from the previous generation of PON to avoid silent windows in uplink traffic. However, additional wavelengths require the ONU to add extra burst LDs, which presents disadvantages in terms of cost and power consumption.

[0004] In summary, there is an urgent need for a technical solution to avoid the PON silent window without increasing cost or power consumption. Summary of the Invention

[0005] To address the aforementioned issues, this disclosure provides a method and apparatus for ONU ranging using wavelength dispersion differences. By utilizing the characteristic of downlink data arrival time differences caused by the dispersion difference of downlink wavelengths, ONU ranging is achieved, thereby enabling PON silent window avoidance.

[0006] In a first aspect, a method for ONU ranging using wavelength dispersion differences, the method comprising:

[0007] The proportional coefficient β is calculated by using the signal transmission time difference Δt3 caused by the dispersion of the initial online ONU and the distance L measured by the PON standard ranging procedure. λ1λ2 ;

[0008] The subsequently launched ONUs use a scaling factor β λ1λ2 The distance to subsequent online ONUs is calculated using the signal transmission time difference Δt3 caused by dispersion.

[0009] Furthermore, the proportional coefficient β is calculated using the signal transmission time difference Δt3 caused by the dispersion of the initially online ONU and the distance L measured by the PON standard ranging procedure. λ1λ2 ,include:

[0010] When the first ONU comes online, L and Δt3 are calculated using the standard ranging procedure, and then β is corrected based on the calculation. λ1λ2 Parameter value, β λ1λ2 =L / Δt3;

[0011] The calculation of Δt3 includes:

[0012] The ONU preparing for deployment listens to the data frames from the OLT; the frame headers sent by 50Gd and dA arrive first as wavelength 1, and then as wavelength 2; the ONU searches for the wavelength 1 synchronization code, and upon finding the wavelength 1 frame synchronization code, enters its pre-synchronization state. It obtains the wavelength 1 frame boundary time by confirming the wavelength 1 frame boundary, and obtains the wavelength 2 frame boundary time by referring to the wavelength 1 operation. It calculates the time difference Δt2 between the wavelength 1 and wavelength 2 frame boundaries and enters the dispersion ranging state; the ONU MAC calculates Δt2 = t based on the frame header times received by 50Gd and dA. dA收 -t 50Gd收 Δt1 and β are extracted from the payload of the data frames broadcast by the OLT. λ1λ2 Parameters; ONU calculates Δt3 = Δt2 - Δt1, which is caused by the different light speeds in the fiber due to dispersion between the two wavelengths.

[0013] Furthermore, subsequent ONUs will be launched using a scaling factor β. λ1λ2 The distance to subsequent online ONUs is calculated based on the signal transmission time difference Δt3 caused by dispersion, including:

[0014] The ONU preparing for deployment listens to the data frames from the OLT; the frame headers sent by 50Gd and dA arrive first as wavelength 1, and then as wavelength 2; the ONU searches for the wavelength 1 synchronization code, and upon finding the wavelength 1 frame synchronization code, enters its pre-synchronization state. It obtains the wavelength 1 frame boundary time by confirming the wavelength 1 frame boundary, and obtains the wavelength 2 frame boundary time by referring to the wavelength 1 operation. It calculates the time difference Δt2 between the wavelength 1 and wavelength 2 frame boundaries and enters the dispersion ranging state; the ONU MAC calculates Δt2 = t based on the frame header times received by 50Gd and dA.dA收 -t 50Gd收 Δt1 and β are extracted from the payload of the data frames broadcast by the OLT. λ1λ2 Parameters; ONU calculates Δt3 = Δt2 - Δt1, which is caused by the difference in light speed in the fiber due to dispersion between the two wavelengths.

[0015] Calculate the distance L = β λ1λ2 ×Δt3; The ONU sets burst data transmission parameters through distance L to complete distance measurement without a silent window.

[0016] Furthermore, the signal transmission time difference caused by ONU dispersion includes:

[0017] In a 50G PON ONU, the optical module adds a wavelength λ for ranging. dA The wavelength λ received for ranging dA It can receive only the XG(S)-PON frame header for timing calculation.

[0018] Furthermore, the signal transmission time difference caused by ONU dispersion includes:

[0019] In a 50G PON ONU, the optical module adds a wavelength λ for ranging. dA Transmission and reception, wavelength λ dA In addition to being used for dispersive ranging timing, it also receives data.

[0020] Furthermore, the signal transmission time difference caused by ONU dispersion includes:

[0021] In a 50G PON ONU, the optical module adds a wavelength λ for ranging. dA The optical module receives wavelength λ for transmission and reception. dA After the pulse is received, it is sent to the MAC of the 50G-PON ONU for timing calculation.

[0022] Furthermore, the signal transmission time difference caused by ONU dispersion includes:

[0023] In a 50G PON ONU, the optical module adds a wavelength λ for ranging. dA The optical module simultaneously receives data at 1342nm and wavelength λ. dA The data from both channels are identical, and the data from the two different channels are cross-calibrated.

[0024] Secondly, a method for ONU ranging using wavelength dispersion differences, employing the aforementioned method for ONU ranging using wavelength dispersion differences, the method comprising:

[0025] In a 50G PON OLT, the MAC module processes data frames and protocols, while the optical module performs physical layer transmission and reception, sending λ... 50Gd For 50G downlink transmission, the wavelength is 1342nm; the optical module receives wavelengths at 1342nm. 50Gd ;

[0026] The optical module adds a new wavelength λ for ranging. dA Sending and receiving.

[0027] Furthermore, it also includes:

[0028] The OLT MAC calculates Δt1 = t based on the frame headers transmitted by 50Gd and dA. dA发 -t 50Gd发 And include Δt1 and β in the data frame payload. λ1λ2 The parameters are broadcast.

[0029] Furthermore, the optical module adds a new wavelength λ for ranging. dA Sending and receiving data includes:

[0030] The wavelength was chosen to be 1577nm, reusing the downlink wavelength of XG(S)-PON; λ in the 50G PON OLT dA The corresponding data transmission frame processing of the MAC of XG(S)-PON reuses the MAC, λ dA The transmitted data is the existing XG(S)-PON data in the current network; the XG(S)-PON frame header is used for timing calculation of ranging.

[0031] Furthermore, the optical module adds a new wavelength λ for ranging. dA Sending and receiving data includes:

[0032] Wavelength selection: 1550nm or other downlink wavelengths not used in the system; MAC in the 50G PON OLT adds λ dA Data transmission channel, λ dA The data being transmitted is 50G-PON downlink data.

[0033] Furthermore, the optical module adds a new wavelength λ for ranging. dA Sending and receiving data includes:

[0034] Wavelength selection: 1550nm or other downlink wavelengths not used in other systems; λ in 50G PON OLT dA A synchronization pulse is sent simultaneously with frame synchronization at a wavelength of 1342nm via the MAC of 50G-PON. dA Only pulses are sent, no data is transmitted.

[0035] Furthermore, the optical module adds a new wavelength λ for ranging.dA Sending and receiving data includes:

[0036] The wavelength selection is a downlink wavelength that is normally transmitted at 50Gbps but not used by the system.

[0037] 50G PON OLT in λ dA The corresponding data transmission frames of the MAC share the 1342nm wavelength MAC of 50G-PON. dA The transmitted data is the same as the 1342nm data.

[0038] Thirdly, an ONU ranging device utilizing wavelength dispersion difference, employing the aforementioned method for ONU ranging utilizing wavelength dispersion difference, includes: an initial unit and a ranging unit;

[0039] The initial unit is used to calculate the scaling factor β based on the signal transmission time difference Δt3 caused by the dispersion of the initially connected ONU and the distance L measured by the PON standard ranging procedure. λ1λ2 ;

[0040] The ranging unit is used by the subsequent online ONU through the scaling factor β. λ1λ2 The distance to subsequent online ONUs is calculated using the signal transmission time difference Δt3 caused by dispersion.

[0041] Fourthly, a transmitting device for ONU ranging using wavelength dispersion differences employs the aforementioned transmitting method for ONU ranging using wavelength dispersion differences.

[0042] In a 50G PON OLT, the MAC module processes data frames and protocols, while the optical module performs physical layer transmission and reception, sending λ... 50Gd For 50G downlink transmission, the wavelength is 1342nm; the optical module receives wavelengths at 1342nm. 50Gd ;

[0043] The optical module adds a new wavelength λ for ranging. dA Sending and receiving.

[0044] Fifthly, an electronic device includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus;

[0045] Memory, which stores computer programs;

[0046] When a processor executes a computer program stored in a memory, it implements either the method described above for ONU ranging using wavelength dispersion differences, or the transmission method described above for ONU ranging using wavelength dispersion differences.

[0047] Sixthly, a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for ONU ranging using wavelength dispersion differences, or implements the above-described method for transmitting data using wavelength dispersion differences for ONU ranging.

[0048] This disclosure includes at least:

[0049] This disclosure fully utilizes the significant differences in downlink wavelengths and dispersion between different generations of PONs, resulting in varying downlink data arrival time differences. It enables ranging of the ONU, thus avoiding the silent window in TDM PON. Furthermore, it fully leverages existing PON signal mechanisms and hardware / software architectures. The ONU only needs an additional wavelength access PD, significantly reducing cost and power consumption compared to adding an additional wavelength transmission LD. It is adaptable to PON networking, offering flexibility and convenience, and is of great significance for implementing low-latency jitter services using TDM PON. It can also be applied to point-to-point communication.

[0050] Other features and advantages of this disclosure will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description and the accompanying drawings. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a schematic diagram of the ranging method according to an embodiment of the present disclosure;

[0053] Figure 2 This is an embodiment of the present disclosure. dA A schematic diagram illustrating the principle of distance measurement when the wavelength is selected as 1577nm;

[0054] Figure 3 Embodiment β of this disclosure λ1λ2 Schematic diagram of parameter value acquisition process;

[0055] Figure 4 This is a schematic diagram illustrating the process of ranging using the dispersion characteristics of different wavelengths in an embodiment of this disclosure;

[0056] Figure 5 This is a schematic diagram of a state machine for dual-wavelength synchronization according to an embodiment of this disclosure;

[0057] Figure 6 This is a schematic diagram of the ranging device structure according to an embodiment of the present disclosure;

[0058] Figure 7 This is a schematic diagram of the electronic device structure according to an embodiment of the present disclosure. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0060] Dispersion is the phenomenon where light travels at different speeds due to variations in frequency (or wavelength) during propagation through a medium. Dispersion is particularly pronounced in optical fiber communication; different wavelengths of light propagate at different speeds within the fiber due to dispersion. In practical applications, even with the same wavelength, the presence of closely spaced wavelength components in the transmitting laser can cause pulse edges to blur after passing through a section of fiber at high transmission rates, affecting communication. With the development of PON (Personal Optical Network) technology, the downlink center wavelength of XG(S)-PON is 1577nm, while that of 50G-PON is 1342nm, a wavelength difference exceeding 230nm. Over a typical 10km distance using PON fiber-to-the-home G.652 fiber, the time difference between these two wavelengths can exceed 20ns.

[0061] like Figure 1 As shown, a method for ONU ranging using wavelength dispersion differences is described, the method comprising:

[0062] S101, using the signal transmission time difference Δt3 caused by the dispersion of the initially online ONU and the distance L measured by the PON standard ranging procedure, calculate the proportional coefficient β. λ1λ2 ;

[0063] S102, subsequent ONUs are launched via a scaling factor β λ1λ2 The distance to subsequent online ONUs is calculated using the signal transmission time difference Δt3 caused by dispersion.

[0064] The specific implementation details are as follows:

[0065] When communication signals of different wavelengths travel through optical fibers, the presence of dispersion differences can lead to time differences in the arrival time of downlink data transmitted simultaneously over a segment of fiber. This difference is used for distance measurement. First, a proportionality coefficient is calculated using the signal transmission difference caused by dispersion at the first ONU to connect and the distance measured by the traditional TDM PON response ranging procedure. The distance to subsequent ONUs is then calculated using this proportionality coefficient and the time difference caused by dispersion.

[0066] like Figure 2 In a 50G PON OLT, the MAC module typically handles data frames and protocols, while the optical module performs physical layer transmission and reception. The transmitting λ... 50Gd To achieve a 50G downlink transmission wavelength of 1342nm, the optical module adds a new transmission wavelength λ. dA The MAC in the 50GPON OLT also increases the transmission wavelength λ. dA The corresponding data transmission frame processing. Meanwhile, in the 50G PON ONU, the optical module, in addition to receiving 1342nm λ... 50Gd In addition, the wavelength λ is increased. dA Received.

[0067] The optical module adds a new transmission wavelength λ dA The wavelength was chosen to be 1577nm, reusing the downlink wavelength of XG(S)-PON. In the 50G PON OLT, λ dA The corresponding data transmission frame processing of the MAC of XG(S)-PON reuses the MAC, λ dA The transmitted data is XG(S)-PON data already present in the existing network. In the 50G PON ONU, the wavelength λ... dA It can receive only the XG(S)-PON frame header for timing calculation.

[0068] β λ1λ2 The parameter value acquisition process is as follows Figure 3 OLT initialization, setting β λ1λ2 The default parameter values ​​can be obtained through theoretical calculations based on wavelength and fiber type, or they can be saved from the last operation of the OLT. When the first ONU comes online, L and Δt3 are calculated using the standard ranging procedure, and then β is corrected based on the calculation. λ1λ2 Record the parameter value and save it. Use β again when a new ONU comes online. λ1λ2 The parameter values ​​are used to perform a distance measurement process without opening a silent window.

[0069] The process of ranging by using the dispersive properties of different wavelengths, such as... Figure 4 S401, OLT MAC calculates Δt1 = t based on the frame header time of 50Gd and dA. dA发 -t50Gd发 And include Δt1 and β in the data frame payload. λ1λ2 The parameters are broadcast. S402, the ONU preparing to go online listens to the OLT's data frames. The ONU MAC calculates Δt2 = t based on the frame header received by 50Gd and the frame header time received by dA. dA收 -t 50Gd收 And extract Δt1 and β from the data frame payload. λ1λ2 Parameters. S403, ONU calculates Δt3 = Δt2 - Δt1, which is caused by the difference in light speed in the fiber due to dispersion between two wavelengths. The distance value L = β is obtained through these parameters. λ1λ2 ×Δt3. The ONU sets burst data transmission parameters by measuring the ranging value, thereby completing the ranging process without a silent window. The ONU listens to the data frames of the OLT as follows: Figure 5 As shown in the state machine, the ONU searches for the synchronization code of wavelength 1. After finding the frame synchronization code of wavelength 1, it enters its pre-synchronization state. Once the frame boundary of wavelength 1 is confirmed, the frame boundary time of wavelength 1 can be obtained. Similarly, wavelength 2 can use the same state machine. After both are synchronized, the frame boundary time difference Δt2 between wavelength 1 and wavelength 2 can be calculated, thus entering the dispersion ranging state. The shorter the wavelength, the faster the speed in the optical fiber. Theoretically, as long as two wavelengths are different and there is a propagation time difference in the optical fiber, ranging can be performed; the greater the wavelength difference between the two wavelengths, the greater the speed difference, and the higher the ranging accuracy. If signals are sent simultaneously, the one arriving first is the shorter wavelength (i.e., wavelength 1), and the one arriving later is the longer wavelength (i.e., wavelength 2). For example, if 1342nm (50Gd) and dA (assuming 1577nm) are sent simultaneously, after traveling through a section of optical fiber, 1342nm will arrive earlier than 1577nm. Therefore, the time difference needs to be obtained by subtracting 50Gd (1342nm) from the time of dA. If the transmission times of the signals are inconsistent, for example, the transmission time of dA (1577nm) is earlier, then the final time needs to be corrected by subtracting 50Gd (1342nm) from the transmission time of dA (1577nm) to obtain a negative number. Correspondingly... Figure 2 Of course, if the 50Gd transmission time is earlier and a positive number is obtained, it can be corrected without being affected. Additionally, if the wavelength chosen for dA is shorter than that of 50Gd (1342nm), then dA will arrive first. Assuming the initial scaling factor β... λ1λ2 It is a negative number, and the final distance measurement value L will be automatically calculated as a positive number. Δt1 can be 0, positive, or negative. When Δt3 is negative, then β... λ1λ2 It is also negative, but it does not affect the calculation of L as positive.

[0070] According to λ dA The wavelength selection method can also choose one of the following options:

[0071] The optical module adds a new transmission wavelength λ dAThe wavelength should be selected as 1550nm or another downlink wavelength not used in the system. A new λ wavelength is added to the MAC of the 50G PON OLT. dA Data transmission channel, λ dA The data transmitted is 50G-PON downlink data, thus increasing the downlink bandwidth. In a 50G PON ONU, the wavelength λ dA In addition to performing dispersion ranging and timing, it also receives data, thereby increasing the downlink bandwidth of the ONU.

[0072] The optical module adds a new transmission wavelength λ dA The wavelength should be 1550nm or another downlink wavelength not used in the system. In a 50G PON OLT, the wavelength is λ. dA The MAC of 50G-PON sends a synchronization pulse simultaneously with the frame synchronization at a wavelength of 1342nm. dA Only pulses are transmitted, not data. In a 50G PON ONU, the optical module receives wavelength λ. dA After the pulse is received, it is sent to the MAC of the 50G-PON ONU for timing calculation.

[0073] The optical module adds a new transmission wavelength λ dA The wavelength selection is a downlink wavelength that can transmit normally at 50Gbps but is not used by the system. In a 50G PON OLT, λ dA The corresponding data transmission frames of the MAC share the 1342nm wavelength MAC of 50G-PON. dA The transmitted data is the same as the 1342nm data. In the 50GPON ONU, both 1342nm data and wavelength λ are received simultaneously. dA The data from both channels is identical, but due to noise during transmission, the ONU will receive some bit errors. To reduce bit errors, the data from the two different channels are mutually corrected, thereby improving the accuracy of data transmission.

[0074] like Figure 6 As shown, an ONU ranging device utilizing wavelength dispersion differences includes: an initial unit 601 and a ranging unit 602;

[0075] Initial unit 601 is used to calculate the scaling factor β based on the signal transmission time difference Δt3 caused by the dispersion of the initially online ONU and the distance L measured by the PON standard ranging procedure. λ1λ2 ;

[0076] The ranging unit 602 is used by the subsequently connected ONU via the scaling factor β. λ1λ2 The distance to subsequent online ONUs is calculated using the signal transmission time difference Δt3 caused by dispersion.

[0077] like Figure 7 As shown, this disclosure provides an electronic device, including a processor 701, a communication interface 702, a memory 703, and a communication bus 704, wherein the processor 701, the communication interface 702, and the memory 703 communicate with each other through the communication bus 704;

[0078] Memory 703 stores computer programs;

[0079] The processor 701 implements the above method when executing a computer program stored in the memory 703.

[0080] This disclosure provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0081] The computer-readable storage medium may be included in the device / apparatus described in the above embodiments; or it may exist independently and not assembled into the device / apparatus. The computer-readable storage medium carries one or more programs that, when executed, implement the method according to the embodiments of this disclosure.

[0082] According to embodiments of this disclosure, the computer-readable storage medium can be a non-volatile computer-readable storage medium, such as, but not limited to, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), or any suitable combination thereof. In this disclosure, the computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0083] Although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A method for ONU ranging using wavelength dispersion differences, characterized in that, The method includes: The proportional coefficient β is calculated by using the signal transmission time difference Δt3 caused by the dispersion of the initial online ONU and the distance L measured by the PON standard ranging procedure. λ1λ2 ; The subsequently launched ONUs use a scaling factor β λ1λ2 The distance to subsequent online ONUs is calculated using the signal transmission time difference Δt3 caused by dispersion.

2. The method for ONU ranging using wavelength dispersion difference according to claim 1, characterized in that, The proportional coefficient β is calculated by using the signal transmission time difference Δt3 caused by the dispersion of the initial online ONU and the distance L measured by the PON standard ranging procedure. λ1λ2 ,include: When the first ONU comes online, L and Δt3 are calculated using the standard ranging procedure, and then β is corrected based on the calculation. λ1λ2 Parameter value, β λ1λ2 =L / Δt3; The calculation of Δt3 includes: The ONU preparing for deployment listens to the data frames from the OLT; the frame headers sent by 50Gd and dA arrive first as wavelength 1, and then as wavelength 2; the ONU searches for the wavelength 1 synchronization code, and upon finding the wavelength 1 frame synchronization code, enters its pre-synchronization state. It obtains the wavelength 1 frame boundary time by confirming the wavelength 1 frame boundary, and obtains the wavelength 2 frame boundary time by referring to the wavelength 1 operation. It calculates the time difference Δt2 between the wavelength 1 and wavelength 2 frame boundaries and enters the dispersion ranging state; the ONU MAC calculates Δt2 = t based on the frame header times received by 50Gd and dA. dA收 -t 50Gd收 Δt1 and β are extracted from the payload of the data frames broadcast by the OLT. λ1λ2 Parameters; ONU calculates Δt3 = Δt2 - Δt1, which is caused by the different light speeds in the fiber due to dispersion between the two wavelengths.

3. The method for ONU ranging using wavelength dispersion difference according to claim 1, characterized in that, The subsequently launched ONUs use a scaling factor β λ1λ2 The distance to subsequent online ONUs is calculated based on the signal transmission time difference Δt3 caused by dispersion, including: The ONU preparing for deployment listens to the data frames from the OLT; the frame headers sent by 50Gd and dA arrive first as wavelength 1, and then as wavelength 2; the ONU searches for the wavelength 1 synchronization code, and upon finding the wavelength 1 frame synchronization code, enters its pre-synchronization state. It obtains the wavelength 1 frame boundary time by confirming the wavelength 1 frame boundary, and obtains the wavelength 2 frame boundary time by referring to the wavelength 1 operation. It calculates the time difference Δt2 between the wavelength 1 and wavelength 2 frame boundaries and enters the dispersion ranging state; the ONU MAC calculates Δt2 = t based on the frame header times received by 50Gd and dA. dA收 -t 50Gd收 Δt1 and β are extracted from the payload of the data frames broadcast by the OLT. λ1λ2 Parameters; ONU calculates Δt3 = Δt2 - Δt1, which is caused by the difference in light speed in the fiber due to dispersion between the two wavelengths. Calculate the distance L = β λ1λ2 ×Δt3; The ONU sets burst data transmission parameters through distance L to complete distance measurement without a silent window.

4. The method for ONU ranging using wavelength dispersion difference according to claim 1, characterized in that, The signal transmission time difference caused by ONU dispersion includes: In a 50G PON ONU, the optical module adds a wavelength λ for ranging. dA The wavelength λ received for ranging dA It can receive only the XG(S)-PON frame header for timing calculation.

5. The method for ONU ranging using wavelength dispersion difference according to claim 1, characterized in that, The signal transmission time difference caused by ONU dispersion includes: In a 50G PON ONU, the optical module adds a wavelength λ for ranging. dA Transmission and reception, wavelength λ dA In addition to being used for dispersive ranging timing, it also receives data.

6. The method for ONU ranging using wavelength dispersion difference according to claim 1, characterized in that, The signal transmission time difference caused by ONU dispersion includes: In a 50G PON ONU, the optical module adds a wavelength λ for ranging. dA The optical module receives wavelength λ for transmission and reception. dA After the pulse is received, it is sent to the MAC of the 50G-PON ONU for timing calculation.

7. The method for ONU ranging using wavelength dispersion difference according to claim 1, characterized in that, The signal transmission time difference caused by ONU dispersion includes: In a 50G PON ONU, the optical module adds a wavelength λ for ranging. dA The optical module simultaneously receives data at 1342nm and wavelength λ. dA The data from both channels are identical, and the data from the two different channels are cross-calibrated.

8. A method for ONU ranging using wavelength dispersion differences, characterized in that, The method for ONU ranging using wavelength dispersion difference according to any one of claims 1-7, the method comprising: In a 50G PON OLT, the MAC module processes data frames and protocols, while the optical module performs physical layer transmission and reception, sending λ... 50Gd For 50G downlink transmission, the wavelength is 1342nm; the optical module receives wavelengths at 1342nm. 50Gd ; The optical module adds a new wavelength λ for ranging. dA Sending and receiving.

9. A transmission method for ONU ranging using wavelength dispersion differences according to claim 8, characterized in that, Also includes: The OLT MAC calculates Δt1 = t based on the frame headers transmitted by 50Gd and dA. dA发 -t 50Gd发 And include Δt1 and β in the data frame payload. λ1λ2 The parameters are broadcast.

10. A transmission method for ONU ranging using wavelength dispersion differences according to claim 8, characterized in that, The optical module adds a new wavelength λ for ranging. dA Sending and receiving data includes: The wavelength was chosen to be 1577nm, reusing the downlink wavelength of XG(S)-PON; λ in the 50G PON OLT dA The corresponding data transmission frame processing of the MAC of XG(S)-PON reuses the MAC, λ dA The transmitted data is the existing XG(S)-PON data in the current network; the XG(S)-PON frame header is used for timing calculation of ranging.

11. A transmission method for ONU ranging using wavelength dispersion difference according to claim 8, characterized in that, The optical module adds a new wavelength λ for ranging. dA Sending and receiving data includes: Wavelength selection: 1550nm or other downlink wavelengths not used in the system; MAC in the 50G PON OLT adds λ dA Data transmission channel, λ dA The data being transmitted is 50G-PON downlink data.

12. A transmission method for ONU ranging using wavelength dispersion difference according to claim 8, characterized in that, The optical module adds a new wavelength λ for ranging. dA Sending and receiving data includes: Wavelength selection: 1550nm or other downlink wavelengths not used in other systems; λ in 50G PON OLT dA A synchronization pulse is sent simultaneously with frame synchronization at a wavelength of 1342nm via the MAC of 50G-PON. dA Only pulses are sent, no data is transmitted.

13. A transmission method for ONU ranging using wavelength dispersion differences according to claim 8, characterized in that, The optical module adds a new wavelength λ for ranging. dA Sending and receiving data includes: The wavelength selection is a downlink wavelength that is normally transmitted at 50Gbps but not used by the system. 50G PON OLT in λ dA The corresponding data transmission frames of the MAC share the 1342nm wavelength MAC of 50G-PON. dA The transmitted data is the same as the 1342nm data.

14. A device for ONU ranging using wavelength dispersion differences, characterized in that, A method for ONU ranging using wavelength dispersion difference according to any one of claims 1-7, comprising: an initial unit and a ranging unit; The initial unit is used to calculate the scaling factor β based on the signal transmission time difference Δt3 caused by the dispersion of the initially connected ONU and the distance L measured by the PON standard ranging procedure. λ1λ2 ; The ranging unit is used by the subsequent online ONU through the scaling factor β. λ1λ2 The distance to subsequent online ONUs is calculated using the signal transmission time difference Δt3 caused by dispersion.

15. A transmitting device for ONU ranging using wavelength dispersion differences, characterized in that, The transmission method for ONU ranging based on wavelength dispersion difference, as described in any one of claims 8-13, is adopted. In a 50G PON OLT, the MAC module processes data frames and protocols, while the optical module performs physical layer transmission and reception, sending λ... 50Gd For 50G downlink transmission, the wavelength is 1342nm; the optical module receives wavelengths at 1342nm. 50Gd ; The optical module adds a new wavelength λ for ranging. dA Sending and receiving.

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