OTN network transmission method and device based on dynamic bandwidth adjustment

Abstract

The invention relates to the technical field of optical communication, in particular to an OTN (Optical Transport Network) network transmission method and device based on dynamic bandwidth adjustment, which converts an OTN rigid pipeline into an elastic intelligent pipeline, remarkably improves the bandwidth resource utilization rate, realizes the millisecond-level agile adjustment of bandwidth by automatically sensing the change of service load, and improves the bandwidth transmission efficiency. The on-demand instant supply requirement of scenes such as cloud service and 5G slicing is met, the service response time is greatly shortened, the rate and power linkage mechanism effectively reduces port power consumption, the green communication development target is met, the technical scheme is achieved in a standard OTN frame structure, existing equipment and an operation and maintenance system are perfectly compatible, smooth network evolution is supported, and the method is suitable for large-scale popularization and application. The multi-time-scale intelligent decision-making architecture not only can quickly deal with burst traffic, but also can realize traffic shaping through a prediction algorithm to avoid link oscillation, and the overhead reconstruction method realizes accurate clock synchronization through in-band signaling to continuously guarantee transmission reliability in the whole dynamic adjustment process.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to an OTN network transmission method and apparatus based on dynamic bandwidth adjustment. Background Technology

[0002] OTN technology is hailed as the core technology of next-generation backbone transmission networks. By introducing concepts such as digital encapsulation, digital multiplexing, and digital cross-connection, it builds a powerful layer for customer signal adaptation, management, and scheduling above the optical layer. OTN defines containers of various rate levels (such as ODU0 / 1 / 2 / 2e / 3 / 4 / flex), providing transparent transmission channels for customer signals of different rates (such as Ethernet, SDH / SONET).

[0003] However, traditional OTN networks are essentially based on "rigid pipes." Once a specific size of ODUk channel is allocated to a service path, the bandwidth of that channel is typically fixed for the lifetime of the connection. This static characteristic exposes many drawbacks when facing the dynamic traffic patterns of modern network applications:

[0004] 1. Rigid and underutilized bandwidth resources: To ensure that services do not experience packet loss or latency jitter during peak traffic, network planners must allocate bandwidth according to peak rates. However, statistics show that the average load rate of most data services is only 30%-50% of the peak rate. This means that more than half of the valuable bandwidth resources are idle most of the time, resulting in huge resource waste and cost pressure.

[0005] 2. Inflexible service provisioning: When users need to temporarily increase or permanently adjust bandwidth, existing OTN networks typically require network administrators to manually reconfigure them through network management systems or control planes (such as ASON / GMPLS). This process can take anywhere from a few minutes to several days, failing to meet the demand for "on-demand, real-time" bandwidth provisioning in scenarios such as cloud services, 5G network slicing, and data center interconnection.

[0006] 3. Low energy efficiency: OTN ports (especially high-speed ports such as G / G / 400G) consume enormous amounts of power. Regardless of the actual traffic they carry, these ports typically operate at full power. During low-load periods, a significant amount of energy is consumed on transmitting “idle” or “lightly loaded” links, which contradicts the goal of green communications.

[0007] To enhance flexibility, relevant standards organizations and manufacturers have explored various approaches. For example, ODUflex (GFP) technology can adjust the size of the ODUflex container based on the Constant Bit Rate (CBR) of the client signal. However, it primarily targets circuit-switched services, and the adjustment process involves recalculating control plane signaling and network paths, resulting in latency in the seconds or even longer, making it difficult to handle millisecond- or microsecond-level traffic bursts. Furthermore, while technologies such as optical orthogonal frequency division multiplexing (O-OFDM) and variable bandwidth optical transceivers based on the optical layer can achieve flexibility at the optical spectrum granularity, they are costly and lack integration with existing OTN electrical layer management and maintenance systems, making smooth deployment in existing networks difficult.

[0008] Therefore, the industry urgently needs an innovative solution that can be implemented on the mainstream OTN electrical layer, is backward compatible with existing devices, and provides fine-grained and fast dynamic bandwidth adjustment capabilities. Summary of the Invention

[0009] The purpose of this invention is to provide an OTN network transmission method and apparatus based on dynamic bandwidth adjustment, which aims to solve the problem of low bandwidth resource utilization.

[0010] To achieve the above objectives, in a first aspect, the present invention provides an OTN network transmission device based on dynamic bandwidth adjustment, comprising a transmitting end and a receiving end; the transmitting end includes a service mapping and caching module, a load monitoring and bandwidth calculation module, a dynamic bandwidth modulation module, an OTN framing and FEC encoding module, and a line interface and optical transmission module; the receiving end includes an optical receiving and clock data recovery module, an OTN deframing and FEC decoding module, a dynamic bandwidth demodulator, and a service demapping and transmission module;

[0011] The service mapping and caching module is used to receive customer-side signals and asynchronously map them to the ODUk frame payload area, while providing elastic caching to absorb clock deviations and phase jitter.

[0012] The load monitoring and bandwidth calculation module is used to monitor service load and generate bandwidth adjustment instructions;

[0013] The dynamic bandwidth modulation module is used to perform rate modulation on the OTN data stream according to the instruction;

[0014] The OTN framing and FEC coding module is used to add OTN frame overhead to the modulated data stream and perform FEC coding.

[0015] The line interface and optical transmitting module are used to convert electrical signals into optical signals and transmit them to the optical fiber;

[0016] The optical receiving and clock data recovery module is used to receive optical signals and recover clock and data;

[0017] The OTN deframe and FEC decoding module is used for frame delimitation, parsing the OTN frame structure and performing FEC decoding;

[0018] The dynamic bandwidth demodulator is used to demodulate the rate and restore the original data clock.

[0019] The service demapping and transmission module is used to extract customer signals from the ODUk frame payload and send them to the customer-side equipment.

[0020] The dynamic bandwidth modulation module includes a symbol-filling modulation unit and an overhead reconstruction modulation unit.

[0021] The symbol-filling modulation unit controls the average effective data rate by inserting or deleting predefined fill symbols in the OTN frame stream.

[0022] The overhead reconstruction modulation unit generates a corresponding bandwidth adjustment control word according to the instruction and writes it into the pre-configured OTN frame overhead byte position.

[0023] The load monitoring and bandwidth calculation module includes a fast response channel and a slow response channel.

[0024] The fast response channel, based on dual threshold comparison, achieves a rapid response at the millisecond to microsecond level.

[0025] The slow response channel is used to predict the business traffic trend in the next few hundred milliseconds to several seconds, and initiate a smooth bandwidth adjustment in advance based on the prediction results to avoid link oscillation caused by rapid adjustment.

[0026] The dynamic bandwidth demodulator includes a symbol stuffing detection and removal unit and an overhead parsing and synchronization unit.

[0027] The symbol padding detection and removal unit is used to locate and remove all padding symbols inserted by the sending end in the data stream;

[0028] The overhead parsing and synchronization unit controls the frequency and phase of the data reading clock according to the information of the control word, so that it is synchronized with the original service clock of the transmitting end.

[0029] Secondly, an OTN network transmission method based on dynamic bandwidth adjustment, used in the OTN network transmission apparatus based on dynamic bandwidth adjustment described in the first aspect, includes the following steps:

[0030] The client-side signal is asynchronously mapped to the ODUk frame payload and buffered. By monitoring the elastic buffer queue depth at multiple time scales and combining traffic prediction with intelligent decision-making of bandwidth adjustment instructions, the OTN data stream rate is dynamically modulated using the symbol filling method or overhead reconstruction method. After OTN framing, FEC encoding and photoelectric conversion, it is sent to the optical fiber line.

[0031] It receives optical signals and completes clock data recovery, OTN deframe and FEC decoding. By identifying the modulation mode of the transmitting end, it performs padding symbol detection and removal or overhead control word parsing to restore the original data clock and achieve precise synchronization. Finally, it extracts the customer signal from the payload and outputs it.

[0032] The section on "asynchronously mapping client-side signals to ODUk frame payloads and buffering them, using multi-timescale monitoring of elastic buffer queue depth combined with intelligent decision-making based on traffic prediction to adjust bandwidth commands, dynamically modulating the OTN data stream rate using symbol stuffing or overhead reconstruction methods, and transmitting it to the fiber optic line after OTN framing, FEC encoding, and photoelectric conversion" includes the following steps:

[0033] The client-side signal is asynchronously mapped to the payload area of ​​the ODUk frame through a general framing procedure or bit synchronization mapping method, and stored in the elastic buffer.

[0034] The queue depth of the elastic buffer is continuously monitored, and the depth is compared with the preset high / low water level thresholds to generate millisecond-level fast adjustment instructions. Optionally, a lightweight traffic prediction algorithm is run to generate predictive adjustment instructions, and the final bandwidth adjustment command is generated by combining the results.

[0035] Modulating the line rate using either the symbol stuffing method or the overhead reconstruction method: When using the symbol stuffing method, the stuffing symbol density ρ is calculated and a predefined IDLE code pattern is inserted at a fixed position in the OTN frame; when using the overhead reconstruction method, the rate adjustment amount is encoded into a control word and written into the reserved overhead byte of the OTN frame.

[0036] The modulated data stream is fed with OTN frame overhead, FEC encoded, and then transmitted to the optical fiber line after photoelectric conversion.

[0037] The process of "receiving optical signals and completing clock data recovery, OTN deframe and FEC decoding, performing padding symbol detection and removal or overhead control word parsing according to the modulation mode of the transmitting end, restoring the original data clock to achieve precise synchronization, and finally extracting the customer signal from the payload and outputting it" includes the following steps:

[0038] The optical signal is converted into an electrical signal, the clock information is extracted by recovering the clock data, and the OTN deframe and FEC decoding are completed.

[0039] For the symbol stuffing method, stuffing symbols are identified and removed, and a phase-locked loop is used to lock the arrival interval of valid frames to generate a synchronization clock; for the overhead reconstruction method, the control word decoding rate offset is extracted from the specified overhead byte, and a numerically controlled oscillator is used to achieve precise clock synchronization.

[0040] The client signal is extracted from the demodulated and recovered OTN frame payload, and the data is completely sent to the client-side equipment using the recovered client-side clock.

[0041] This invention discloses an OTN network transmission device based on dynamic bandwidth adjustment. This invention transforms the rigid OTN pipeline into a flexible intelligent pipeline, significantly improving bandwidth resource utilization and solving the problem of idle and wasted traditional network resources. By automatically sensing changes in service load, it achieves millisecond-level agile bandwidth adjustment, meeting the on-demand and real-time supply needs of scenarios such as cloud services and 5G slicing, greatly shortening service response time. The rate and power linkage mechanism effectively reduces port power consumption, aligning with the development goals of green communication. The technical solution is implemented within the standard OTN frame structure, perfectly compatible with existing equipment and maintenance systems, and supports smooth network evolution. The multi-timescale intelligent decision-making architecture can quickly respond to sudden traffic surges and achieve traffic shaping through predictive algorithms, avoiding link oscillations. The device can be integrated with FPGA or ASIC at high density, possessing excellent scalability and suitable for high-speed port deployment. The overhead reconstruction method achieves precise clock synchronization through in-band signaling, continuously ensuring transmission reliability throughout the dynamic adjustment process. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a logical structure block diagram of an OTN network transmission device based on dynamic bandwidth adjustment provided by the present invention.

[0044] Figure 2 This is a detailed flowchart of the sending end processing method provided in the embodiments of the present invention.

[0045] Figure 3 This is a detailed flowchart of the receiving end processing method provided in the embodiments of the present invention.

[0046] Figure 4 This is a schematic diagram illustrating the dynamic bandwidth adjustment principle of the "symbol filling method" in Embodiment 1 of the present invention.

[0047] Figure 5This is a schematic diagram showing the position of the bandwidth adjustment control word in the OTN frame structure of the "overhead reconstruction method" in Embodiment 2 of the present invention.

[0048] Figure 6 This is a schematic diagram illustrating the working principle of the multi-timescale load monitoring and bandwidth decision engine in this embodiment of the invention.

[0049] Figure 7 This is a flowchart of an OTN network transmission method based on dynamic bandwidth adjustment provided by the present invention.

[0050] In the diagram: 1-Transmitter, 2-Receiver; 11-Service mapping and buffering module, 12-Load monitoring and bandwidth calculation module, 13-Dynamic bandwidth modulation module, 14-OTN framing and FEC encoding module, 15-Line interface and optical transmission module; 121-Fast response channel, 122-Slow response channel, 131-Symbol stuffing modulation unit, 132-Overhead reconstruction modulation unit; 21-Optical reception and clock data recovery module, 22-OTN deframing and FEC decoding module, 23-Dynamic bandwidth demodulator, 24-Service demapping and transmission module; 231-Symbol stuffing detection and removal unit, 232-Overhead parsing and synchronization unit. Detailed Implementation

[0051] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0052] Please see Figure 1 In a first aspect, the present invention provides an OTN network transmission device based on dynamic bandwidth adjustment, comprising a transmitting end 1 and a receiving end 2; the transmitting end 1 includes a service mapping and caching module 11, a load monitoring and bandwidth calculation module 12, a dynamic bandwidth modulation module 13, an OTN framing and FEC encoding module 14, and a line interface and optical transmission module 15; the receiving end 2 includes an optical receiving and clock data recovery module 21, an OTN deframing and FEC decoding module 22, a dynamic bandwidth demodulator 23, and a service demapping and transmission module 24;

[0053] The service mapping and caching module 11 is used to receive customer-side signals and asynchronously map them to the ODUk frame payload area, while providing elastic caching to absorb clock deviation and phase jitter.

[0054] The load monitoring and bandwidth calculation module 12 is used to monitor service load and generate bandwidth adjustment instructions;

[0055] The dynamic bandwidth modulation module 13 is used to perform rate modulation on the OTN data stream according to the instruction.

[0056] The OTN framing and FEC coding module 14 is used to add OTN frame overhead to the modulated data stream and perform FEC coding.

[0057] The line interface and optical transmitting module 15 are used to convert electrical signals into optical signals and transmit them to the optical fiber;

[0058] The optical receiving and clock data recovery module 21 is used to receive optical signals and recover clock and data;

[0059] The OTN deframe and FEC decoding module 22 is used for frame delimitation, parsing the OTN frame structure and performing FEC decoding.

[0060] The dynamic bandwidth demodulator 23 is used to demodulate the rate and restore the original data clock.

[0061] The service demapping and transmission module 24 is used to extract the customer signal from the ODUk frame payload and send it to the customer-side device.

[0062] In this embodiment, the service mapping and caching module 11 is responsible for receiving client-side signals (such as IP / Ethernet packets) and asynchronously mapping them to the payload area of ​​ODUk (usually ODUflex) frames using standard methods such as general framing procedures or bit synchronization mapping. This module includes a first-in-first-out elastic buffer to absorb frequency deviations and phase jitter between the client signal clock and the local OTN system clock, and to provide sampling points for subsequent load monitoring. The load monitoring and bandwidth calculation module 12 is the "brain" of the system. It continuously monitors the data inventory (queue depth) of the elastic buffer. This engine supports multi-timescale monitoring and control strategies; the dynamic bandwidth modulation module 13 is the core hardware functional block of this invention. It receives instructions from the bandwidth decision engine and specifically executes one or a combination of the following two modulation methods: the OTN framing and forward error correction coding module receives the rate-modulated data stream from the dynamic bandwidth modulation module 13, adds complete OTN frame overhead (such as frame positioning, path tracing, BIP-8, etc.) to it, and performs FEC encoding to form an OTU frame structure conforming to the ITU-T G.709 / G.798 standard. The line interface and optical transmission module 15 converts digital electrical signals into optical signals and transmits them into the optical fiber through a laser. The driving circuit of this module preferably supports power control functions linked with the dynamic bandwidth modulation module 13, that is, appropriately reducing the transmission power at low rates to achieve energy saving.

[0063] The optical receiving and clock data recovery module 21 receives optical signals, converts them into electrical signals, and recovers preliminary clock and data information from the input signals through a CDR circuit. The OTN deframe and FEC decoding module 22 performs frame delimitation, parses the OTN frame structure, and performs FEC decoding to correct bit errors generated during transmission. The dynamic bandwidth demodulator 23 is the core module corresponding to the transmitter 1 modulator, responsible for recovering the original standard OTN frame rate from the modulated signal. It also includes two operating modes. The service demapping and transmission module 24 extracts the customer signal from the recovered ODUk frame payload and uses the recovered customer-side clock to send data to the customer-side equipment.

[0064] The receiver 2 includes: The optical receiving and clock data recovery module 21: receives the optical signal, converts it into an electrical signal, and recovers preliminary clock and data information from the input signal using a CDR circuit. The OTN deframe and FEC decoding module 22: performs frame delimitation, parses the OTN frame structure, and performs FEC decoding to correct bit errors generated during transmission. The dynamic bandwidth demodulator 23: This is the core module corresponding to the modulator at the transmitter 1, responsible for recovering the original standard OTN frame rate from the modulated signal. The service demapping and transmission module 24: extracts the customer signal from the recovered ODUk frame payload and uses the recovered customer-side clock to send data to the customer-side equipment.

[0065] Furthermore, the dynamic bandwidth modulation module 13 includes a symbol filling modulation unit 131 and an overhead reconstruction modulation unit 132.

[0066] The symbol-filling modulation unit 131 changes the average effective data rate by controllably inserting or deleting predefined fill symbols in the OTN frame stream;

[0067] The overhead reconstruction modulation unit 132 generates a corresponding bandwidth adjustment control word according to the instruction and writes it into the pre-configured OTN frame overhead byte position.

[0068] In this embodiment, the symbol stuffing modulation unit 131 includes a programmable symbol generator (generating a specific IDLE code pattern) and insertion control logic. According to the rate adjustment instructions, this logic precisely controls the insertion position (inter-frame or intra-frame) and density of stuffing symbols in the OTN frame stream. The overhead reconstruction modulation unit 132 includes a control word generator and overhead overwrite logic. It generates the corresponding bandwidth adjustment control word according to the instructions and writes it to the pre-configured OTN frame overhead byte position.

[0069] Furthermore, the load monitoring and bandwidth calculation module 12 includes a fast response channel 121 and a slow response channel 122;

[0070] The fast response channel 121, based on dual threshold comparison, achieves a rapid response at the millisecond to microsecond level;

[0071] The slow response channel 122 is used to predict the service traffic trend in the next few hundred milliseconds to several seconds, and initiate a smooth bandwidth adjustment in advance based on the prediction results to avoid link oscillation caused by rapid adjustment.

[0072] In this embodiment, the fast response channel 121 achieves millisecond-to-microsecond rapid response based on a simple dual-threshold comparison (high waterline HWL, low waterline LWL). When the queue depth exceeds HWL, an "increase" request is immediately triggered; when it falls below LWL, a "decrease" request is triggered. The slow response channel 122 can integrate a lightweight machine learning predictor (such as an ARIMA model based on time series analysis or simple linear prediction) to predict the business traffic trend for the next few hundred milliseconds to several seconds. Based on the prediction results, a gradual bandwidth adjustment is initiated in advance to avoid link oscillations caused by rapid adjustments, thus achieving traffic shaping.

[0073] Furthermore, the dynamic bandwidth demodulator 23 includes a symbol stuffing detection and removal unit 231 and an overhead parsing and synchronization unit 232;

[0074] The symbol filling detection and removal unit 231 is used to locate and remove all filling symbols inserted by the sending end 1 in the data stream;

[0075] The overhead parsing and synchronization unit 232 controls the frequency and phase of the data reading clock according to the information of the control word, so that it is synchronized with the original service clock of the transmitting end 1.

[0076] In this embodiment, the symbol stuffing detection and removal unit 231 includes a pattern recognizer matched with the transmitter 1, used to locate and remove all stuffing symbols inserted by the transmitter 1 in the data stream. Simultaneously, it drives a synchronous phase-locked loop (PLL), which dynamically adjusts its output clock frequency according to the arrival rate of valid data to ensure correct data sampling. The overhead parsing and synchronization unit 232 reads the bandwidth adjustment control word from a specified position in the deframed OTN overhead. Based on the information in the control word, it precisely controls the frequency and phase of the data reading clock to synchronize it with the original service clock of the transmitter 1, thereby retrieving the data without errors.

[0077] Example:

[0078] 1. Device Implementation (Reference) Figure 1 )

[0079] The dynamic bandwidth modulation module at the transmitting end primarily activates its symbol filling modulation unit. This unit consists of a programmable state mechanism implemented by an FPGA or ASIC.

[0080] Fill symbol definition: We define the fill symbol as a 66B code block, the content of which is 0x1E (4B header) + 0xFFFFFFFFFFFFFF (62B data). This code pattern is easy to be identified at the receiver and has good DC balance.

[0081] Insertion Mechanism: The insertion control logic operates on an OTN frame cycle. After each OTN frame transmission ends, it does not immediately send the next frame. Instead, it determines how many fill symbols to insert based on the "fill symbol density (ρ)" parameter issued by the current bandwidth decision engine. ρ is a value between 0 and ρ_max (e.g., 0.2, i.e., 20%). ρ=0 means no fill symbols are inserted, and the line operates at the highest effective rate; ρ=0.2 means that 20% of the symbols per unit time are fill symbols, and the effective rate is 80% of the nominal rate.

[0082] Rate Calculation: The bandwidth decision engine calculates the target effective rate according to the formula R_effective=R_line*(1-ρ), where R_line is the fixed line symbol rate of the optical module.

[0083] The receiver's dynamic bandwidth demodulator primarily activates its symbol stuffing detection and rejection unit. This unit is also implemented using an FPGA.

[0084] Pattern recognition: Internally, there is a 66B pattern recognizer that matches the transmitter, continuously scanning the input bitstream. Once a predefined padding symbol pattern is recognized, it is marked as "invalid".

[0085] Data removal and clock recovery: The data path logic ignores all marked symbols. Simultaneously, a phase-locked loop (PLL) with a wide capture range (e.g., ±0 ppm) locks onto the arrival time of valid OTN frames. The PLL's output clock is the recovered service clock, used to feed the continuous valid OTN frame data (after removing padding symbols) into the subsequent OTN deframe module.

[0086] Please see Figures 2 to 7 Secondly, an OTN network transmission method based on dynamic bandwidth adjustment, used in the OTN network transmission apparatus based on dynamic bandwidth adjustment described in the first aspect, includes the following steps:

[0087] S1 asynchronously maps the client-side signal to the ODUk frame payload and buffers it. By monitoring the elastic buffer queue depth at multiple time scales and combining traffic prediction with intelligent decision-making bandwidth adjustment instructions, it dynamically modulates the OTN data stream rate using the symbol filling method or overhead reconstruction method. After OTN framing, FEC encoding and photoelectric conversion, it is sent to the optical fiber line.

[0088] S11 asynchronously maps the client-side signal to the payload area of ​​the ODUk frame through a general framing procedure or bit synchronization mapping method, and stores it in the elastic buffer.

[0089] Specifically, this involves business adaptation and caching. Client signals are asynchronously mapped to the ODUflex payload and stored in an elastic cache.

[0090] S12 continuously monitors the queue depth of the elastic buffer, compares the depth with preset high / low water level thresholds to generate millisecond-level fast adjustment instructions, and optionally runs a lightweight traffic prediction algorithm to generate predictive adjustment instructions, and finally generates the final bandwidth adjustment command.

[0091] Specifically, the cache queue depth is monitored in real time. The depth is compared with preset static thresholds (HWL, LWL) to generate a fast adjustment command. (Optional): A traffic prediction algorithm is run to predict short-term future load based on historical traffic data, generating a predictive adjustment command. The fast and predictive commands are combined, and a final bandwidth adjustment command (e.g., "increase speed to 105% nominal rate" or "decrease speed to 95% nominal rate") is generated based on a decision-making algorithm (e.g., priority arbitration, weighted average).

[0092] S13 modulates the line rate using either the symbol stuffing method or the overhead reconstruction method: When using the symbol stuffing method, the stuffing symbol density ρ is calculated and a predefined IDLE code pattern is inserted at a fixed position in the OTN frame; when using the overhead reconstruction method, the rate adjustment amount is encoded into a control word and written into the reserved overhead byte in the OTN frame.

[0093] Specifically, in Mode A (symbol stuffing): the modulator calculates the required stuffing symbol density (ρ) based on the command. For example, the target rate R_target = R_nominal * (1-ρ), where ρ is the proportion of stuffing symbols. The symbol insertion controller inserts the corresponding number of IDLE symbols at fixed positions in the OTN frame (e.g., after each frame) according to the calculated ρ.

[0094] Mode B (Overhead Reconstruction): The modulator encodes the rate adjustment (e.g., +5%) into a specific control word (e.g., a 16-bit codeword). In each OTN frame period, this control word is written to a predefined overhead byte position.

[0095] S14 adds OTN frame overhead to the modulated data stream, performs FEC encoding, and then transmits it to the optical fiber line after photoelectric conversion.

[0096] Specifically, signal shaping and transmission. This involves OTN framing, FEC encoding, and then transmission to the line after photoelectric conversion.

[0097] S2 receives optical signals and completes clock data recovery, OTN deframe and FEC decoding. By identifying the modulation mode of transmitter 1, it performs corresponding padding symbol detection and removal or overhead control word parsing to restore the original data clock and achieve precise synchronization. Finally, it extracts the customer signal from the payload and outputs it.

[0098] S21 converts optical signals into electrical signals, recovers and extracts clock information through clock data, and completes OTN deframe and FEC decoding;

[0099] Specifically, signal reception and preliminary processing include photoelectric conversion, CDR and OTN deframes, and FEC decoding.

[0100] For the symbol stuffing method, S22 identifies and removes stuffing symbols, and uses a phase-locked loop to lock the arrival interval of valid frames to generate a synchronous clock; for the overhead reconstruction method, it extracts the control word decoding rate offset from the specified overhead byte and controls the numerically controlled oscillator to achieve precise clock synchronization.

[0101] Specifically, the symbol pattern detector scans the input bit stream, identifies and marks the positions of all padding symbols; the data path logic removes all padding symbols based on the marking information; and the phase-locked loop generates a synchronization clock based on the arrival interval of valid data (OTN frames) for subsequent data processing.

[0102] Extract the bandwidth adjustment control word from the specified overhead position of each OTN frame; parse the current rate offset based on the control word; control a programmable clock generator to make its output frequency precisely synchronized with the original service clock of transmitter 1;

[0103] S23 extracts the client signal from the demodulated and recovered OTN frame payload and uses the recovered client-side clock to send the data completely to the client-side equipment.

[0104] Specifically, this involves service extraction and output. The client's services are mapped from the demodulated standard OTN frames and then sent to the client.

[0105] Example:

[0106] Workflow (Reference) Figure 2 , Figure 3 , Figure 4 )

[0107] Assume the initial state is low load, ρ=0.1 (i.e. 10% of the bandwidth is occupied by fill symbols).

[0108] Sender:

[0109] S110: GbE service flows are mapped to ODUflex frames.

[0110] S: The bandwidth decision engine detected that the cache queue depth was rising rapidly and exceeding HWL. It immediately calculated a new ρ_new=0.02 in order to improve the effective rate.

[0111] S (Mode A): The symbol-stuffing modulation unit receives a command to reduce the number of stuffing symbols inserted after each OTN frame from the corresponding ρ=0.1 to the corresponding ρ=0.02. For example... Figure 4 As shown, during periods of high load, the gaps (padding symbols) between OTN frames become significantly narrower and fewer.

[0112] S140: The signal is sent.

[0113] Receiver:

[0114] S / S (Mode A): The optical module and deframe module at the receiver are operating normally. The symbol stuffing detection and removal unit detects a significant reduction in the number of stuffing symbol patterns identified per unit time, and determines that the line speed has been increased. It quickly adjusts the PLL frequency to read valid data at a higher clock rate and accurately removes the remaining few stuffing symbols.

[0115] S: The recovered ODUflex frame is demapped, and the GbE service flow is sent out completely.

[0116] Example 2: Implementation based on the overhead reconstruction method (OR-DBM)

[0117] This embodiment focuses on describing the enhanced implementation using the "overhead refactoring method".

[0118] 1. Device Implementation

[0119] The dynamic bandwidth modulation module at the transmitting end mainly activates its overhead reconfiguration modulation unit.

[0120] Control channel selection: Reference Figure 5 We select two consecutive reserved bytes (e.g., FCC1 and FCC2) in the OTUk overhead region as the bandwidth adjustment control channel. These two bytes are reserved bytes in the standard, and their contents are ignored by legacy devices.

[0121] Control word encoding: We encode the offset (ΔR) of the target rate relative to the nominal rate. For example, the offset is represented by a 16-bit binary number, ranging from -10% to +10%, with a precision of 0.01%. When a 5% speedup is required, the control word is set to 0x01F4 (corresponding to +5.00%).

[0122] Overhead overwriting: Before OTN framing, the overhead reconstruction unit replaces the FCC1 and FCC2 bytes in the OTN frame to be sent with the currently calculated control words.

[0123] The receiver's dynamic bandwidth demodulator primarily activates its overhead resolution and synchronization units.

[0124] Control word extraction: After completing OTN deframe, this unit extracts a 16-bit control word from the FCC1 and FCC2 byte positions of each OTN frame.

[0125] Precise synchronization: The control word is decoded to obtain ΔR. This information is fed into a high-precision numerically controlled oscillator (CNC), and the DCO adjusts its output frequency according to ΔR, f_out = f_nominal * (1 + ΔR). This recovered clock is used to read the OTN frame payload from the buffer, ensuring precise synchronization with the transmitting end's service clock. This method does not rely on minor clock adjustments by the CDR circuit, thus making it more accurate and reliable.

[0126] 2. Work Process

[0127] The process is similar to that of Example 1, with the main difference being steps S and S':

[0128] S (Mode B): Bandwidth decision engine commands are accelerated by 5%. The overhead reconstruction unit continuously writes 0x01F4 into the FCC1 / FCC2 bytes of each sent OTN frame.

[0129] S (Mode B): The overhead parsing unit at the receiver reads 0x01F4 from each frame and learns that the current rate offset is +5%. It immediately sets the local clock frequency to 1.05 times the nominal frequency, thereby achieving lossless data recovery.

[0130] Example 3: Hybrid Mode and Intelligent Decision Making

[0131] In practical products, both modes can be combined. For example, Sign-Fill-Damage Method (SS-DBM) can be used for large-scale, coarse-grained rate adjustments (e.g., ±20%), while Overhead Restructuring Method (OR-DBM) can be used for small-scale, fine-grained rate fine-tuning (e.g., ±0.5%). The bandwidth decision engine can become more intelligent (see reference). Figure 6 By combining real-time queue monitoring, short-term traffic prediction, and strategies issued by the network controller, optimal bandwidth control can be achieved at multiple time scales and granularities.

[0132] The above-disclosed embodiments are merely preferred embodiments of the OTN network transmission method and apparatus based on dynamic bandwidth adjustment of the present invention. They should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that implementing all or part of the above embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. An OTN network transmission device based on dynamic bandwidth adjustment, characterized in that, It includes a transmitting end and a receiving end; the transmitting end includes a service mapping and caching module, a load monitoring and bandwidth calculation module, a dynamic bandwidth modulation module, an OTN framing and FEC encoding module, and a line interface and optical transmission module; the receiving end includes an optical receiving and clock data recovery module, an OTN deframing and FEC decoding module, a dynamic bandwidth demodulator, and a service demapping and transmission module; The service mapping and caching module is used to receive customer-side signals and asynchronously map them to the ODUk frame payload area, while providing elastic caching to absorb clock deviations and phase jitter. The load monitoring and bandwidth calculation module is used to monitor service load and generate bandwidth adjustment instructions; The dynamic bandwidth modulation module is used to perform rate modulation on the OTN data stream according to the instruction; The OTN framing and FEC coding module is used to add OTN frame overhead to the modulated data stream and perform FEC coding. The line interface and optical transmitting module are used to convert electrical signals into optical signals and transmit them to the optical fiber; The optical receiving and clock data recovery module is used to receive optical signals and recover clock and data; The OTN deframe and FEC decoding module is used for frame delimitation, parsing the OTN frame structure and performing FEC decoding; The dynamic bandwidth demodulator is used to recover the original standard OTN frame rate from the modulated signal. The service demapping and transmission module is used to extract customer signals from the ODUk frame payload and send them to the customer-side equipment.

2. The OTN network transmission device based on dynamic bandwidth adjustment as described in claim 1, characterized in that, The dynamic bandwidth modulation module includes a symbol-filling modulation unit and an overhead reconstruction modulation unit. The symbol-filling modulation unit controls the average effective data rate by inserting or deleting predefined fill symbols in the OTN frame stream. The overhead reconstruction modulation unit generates a corresponding bandwidth adjustment control word according to the instruction and writes it into the pre-configured OTN frame overhead byte position.

3. The OTN network transmission device based on dynamic bandwidth adjustment as described in claim 2, characterized in that, The load monitoring and bandwidth calculation module includes a fast response channel and a slow response channel; The fast response channel, based on dual threshold comparison, achieves a rapid response at the millisecond to microsecond level. The slow response channel is used to predict the business traffic trend in the next few hundred milliseconds to several seconds, and initiate a smooth bandwidth adjustment in advance based on the prediction results to avoid link oscillation caused by rapid adjustment.

4. The OTN network transmission device based on dynamic bandwidth adjustment as described in claim 1, characterized in that, The dynamic bandwidth demodulator includes a symbol stuffing detection and removal unit and an overhead parsing and synchronization unit; The symbol padding detection and removal unit is used to locate and remove all padding symbols inserted by the sending end in the data stream; The overhead parsing and synchronization unit controls the frequency and phase of the data reading clock according to the information of the control word, so that it is synchronized with the original service clock of the transmitting end.

5. An OTN network transmission method based on dynamic bandwidth adjustment, used in the OTN network transmission apparatus based on dynamic bandwidth adjustment as described in any one of claims 1-4, characterized in that, Includes the following steps: The client-side signal is asynchronously mapped to the ODUk frame payload and buffered. By monitoring the elastic buffer queue depth at multiple time scales and combining traffic prediction with intelligent decision-making of bandwidth adjustment instructions, the OTN data stream rate is dynamically modulated using the symbol filling method or overhead reconstruction method. After OTN framing, FEC encoding and photoelectric conversion, it is sent to the optical fiber line. It receives optical signals and completes clock data recovery, OTN deframe and FEC decoding. By identifying the modulation mode of the transmitting end, it performs padding symbol detection and removal or overhead control word parsing to restore the original data clock and achieve precise synchronization. Finally, it extracts the customer signal from the payload and outputs it.

6. The OTN network transmission method based on dynamic bandwidth adjustment as described in claim 5, characterized in that, The process of "asynchronously mapping client-side signals to ODUk frame payloads and buffering them, using multi-timescale monitoring of elastic buffer queue depth combined with intelligent decision-making based on traffic prediction to adjust bandwidth commands, dynamically modulating the OTN data stream rate using symbol stuffing or overhead reconstruction methods, and transmitting it to the fiber optic line after OTN framing, FEC encoding, and photoelectric conversion" includes the following steps: The client-side signal is asynchronously mapped to the payload area of ​​the ODUk frame using a general framing procedure or bit synchronization mapping method, and stored in the elastic buffer. The queue depth of the elastic buffer is continuously monitored, and the depth is compared with the preset high / low water level thresholds to generate millisecond-level fast adjustment instructions. Optionally, a lightweight traffic prediction algorithm is run to generate predictive adjustment instructions, and the final bandwidth adjustment command is generated by combining the results. Modulating the line rate using either the symbol stuffing method or the overhead reconstruction method: When using the symbol stuffing method, the stuffing symbol density ρ is calculated and a predefined IDLE code pattern is inserted at a fixed position in the OTN frame; when using the overhead reconstruction method, the rate adjustment amount is encoded into a control word and written into the reserved overhead byte of the OTN frame. The modulated data stream is fed with OTN frame overhead, FEC encoded, and then transmitted to the optical fiber line after photoelectric conversion.

7. The OTN network transmission method based on dynamic bandwidth adjustment as described in claim 5, characterized in that, The process of "receiving optical signals and completing clock data recovery, OTN deframe and FEC decoding, performing padding symbol detection and removal or overhead control word parsing according to the modulation mode of the transmitting end, restoring the original data clock to achieve precise synchronization, and finally extracting the customer signal from the payload and outputting it" includes the following steps: The optical signal is converted into an electrical signal, the clock information is extracted by recovering the clock data, and OTN deframe and FEC decoding are completed. For the symbol stuffing method, stuffing symbols are identified and removed, and a phase-locked loop is used to lock the arrival interval of valid frames to generate a synchronization clock; for the overhead reconstruction method, the control word decoding rate offset is extracted from the specified overhead byte, and a numerically controlled oscillator is used to achieve precise clock synchronization. The client signal is extracted from the demodulated and recovered OTN frame payload, and the data is completely sent to the client-side equipment using the recovered client-side clock.

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