Inverted 5b8b code-based optical label switching system, method and apparatus

Abstract

The application relates to the technical field of communication, in particular to a cursor label exchange system, method and equipment based on reverse 5B8B code. The system comprises a signal generating module, a parallel modulator, a coupler and a signal receiving module. The signal generating module is used for generating a label signal and a load signal; the parallel modulator is used for modulating an optical carrier by using the load signal and the label signal to obtain a quadrature modulation signal; the coupler is used for splitting the quadrature modulation signal into a label receiving signal and a load receiving signal; and the signal receiving module is used for demodulating the label receiving signal and the load receiving signal to recover the label signal and the load signal. The application has the beneficial technical effects of introducing a simple and low-cost line coding technology into the optical label exchange and combining a quadrature modulation scheme to improve the spectral utilization efficiency of the optical label channel on the basis of reducing the crosstalk between the load signal and the label signal.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and more specifically to an optical tag switching system, method, and device based on inverted 5B8B codes. Background Technology

[0002] Optical Label Switching (OLS) is a promising solution for data exchange in today's rapidly growing packet-based internet traffic and data centers. Currently, most OLS technologies employ quadrature modulation, which involves superimposing non-amplitude modulated tag signals onto Manchester-coded or pulse position modulated intensity shift keying (ASK) payload signals. Common quadrature modulation methods include: Quadrature Amplitude Modulation (QAM), Orthogonal Frequency Division Multiplexing (OFDM), Coded Orthogonal Frequency Division Multiplexing (COFDM), Interleaved Quadrature Quadrature Phase Shift Keying (OQPSK), and π / 4 Quadrature Phase Shift Keying (π / 4-DQPSK).

[0003] In optical tag switching technology, the non-amplitude modulation of tag signals mainly includes three methods: frequency shift keying (FSK), differential phase shift keying (DPSK), and polarization shift keying (PolSK). However, since polarization shift keying is sensitive to polarization rotation angle, and frequency shift keying occupies more wavelength resources and suffers from more dispersion, differential phase shift keying (DPSK) is the most widely used among the three modulation methods.

[0004] However, high extinction ratio ASK modulation degrades DPSK demodulation performance. Simultaneously, in quadrature modulation, the non-amplitude modulated tag signal is subject to crosstalk from amplitude fluctuations caused by ASK modulation. Therefore, to reduce this crosstalk, ASK payload signals are typically smoothed by reducing the extinction ratio or changing the code pattern. However, reducing the extinction ratio (ER) of the ASK payload signal also degrades its quality. Therefore, it is necessary to investigate an optical tag switching method that can improve the spectral efficiency of the optical tag channel, reduce the impact on payload signal quality, and reduce crosstalk between the payload signal and the tag signal.

[0005] For example, Chinese patent CN102377725A, published on March 14, 2012, discloses an optical tag processing method and an optical packet switching method based on OFDM subcarriers. This method includes: each node through which the packet data passes modulates routing information onto a subcarrier in the OFDM band that has a different wavelength than the payload optical carrier, using OFDM modulation. Each node uses a different subcarrier; then, it synchronously couples with the optical tag signal of the previous node to generate an optical tag for that node. This eliminates the need for optical tag erasure and rewriting during optical tag switching, improves the spectral efficiency of the optical tag channel and the transmission efficiency of the optical payload channel, and simplifies the structure of optical packet switching network nodes. However, this technical solution does not solve the problems of the detrimental impact of optical tag switching on the payload signal and the significant crosstalk between the payload signal and the tag signal in existing technologies. Summary of the Invention

[0006] The technical problem to be solved by this invention is that there is a large crosstalk between the payload signal and the tag signal in current optical tag switching. This invention proposes an optical tag switching system, method and equipment based on inverted 5B8B code. By introducing a simple and low-cost line coding technology and combining it with an orthogonal modulation scheme in optical tag switching, the spectral utilization efficiency of the optical tag channel can be improved while reducing the crosstalk between the payload signal and the tag signal.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: an optical tag switching system based on inverted 5B8B code, used to realize the switching of optical tag signals of pseudo-random binary data, including:

[0008] A signal generation module is used to generate tag signals and payload signals, and output the tag signals and payload signals to a parallel modulator;

[0009] A parallel modulator is used to modulate an optical carrier using the payload signal and tag signal output by the signal generation module to obtain an orthogonal modulated signal, and output the orthogonal modulated signal.

[0010] A coupler is used to split the quadrature modulation signal into a tag receiving signal and a payload receiving signal;

[0011] The signal receiving module is used to demodulate the tag received signal and the payload received signal to recover the tag signal and the payload signal.

[0012] Preferably, the tag signal generated by the signal generation module is pseudo-random binary data modulated by DPSK, and the payload signal generated by the signal generation module is inverted 5B8B code data.

[0013] Preferably, the parallel modulator includes:

[0014] A phase modulator is used to perform DPSK modulation on an optical carrier using a tag signal generated by the signal generation module;

[0015] A Mach-Zehnder modulator is used to perform ASK modulation on an optical carrier using a load signal generated by the signal generation module.

[0016] Preferably, the orthogonal modulation signal output by the parallel modulator is transmitted to the coupler via a single-mode fiber, a dispersion-compensating fiber, and an adjustable optical attenuator.

[0017] Preferably, the signal receiving module includes:

[0018] The tag receiving signal demodulation unit is used to demodulate the tag receiving signal and recover the tag signal;

[0019] The load receiving signal demodulation unit is used to demodulate the load receiving signal and recover the load signal.

[0020] Preferably, the tag receiving signal demodulation unit includes:

[0021] A first low-pass filter is used to filter the received signal of the tag to obtain an optical signal carrying the DPSK tag signal;

[0022] The delay interferometer is used to perform interference superposition on the optical signal obtained after filtering by the first low-pass filter, and to obtain the superimposed optical signal and output it to the first photodetector.

[0023] The first photodetector is used to convert the optical signal after interference superposition into an electrical signal, recover the tag signal, and output the recovered tag signal to the first signal receiving end;

[0024] The first signal receiving end is used to receive the tag signal recovered by the first photodetector.

[0025] Preferably, the payload receiving signal demodulation unit includes:

[0026] A second low-pass filter is used to filter the received signal of the payload to obtain an optical signal carrying the ASK payload signal;

[0027] The second photodetector is used to convert the optical signal obtained after filtering by the second low-pass filter into an electrical signal to recover the load signal.

[0028] The second signal receiving end is used to receive the load signal recovered by the second photodetector.

[0029] A method for switching optical tags based on inverted 5B8B codes is used to switch optical tag signals using pseudo-random binary data, and includes the following steps:

[0030] Generate inverted 5B8B code data, use the inverted 5B8B code data as the payload signal, and use the pseudo-random binary data modulated by DPSK as the tag signal.

[0031] The optical carrier is modulated using the payload signal and the tag signal to obtain an orthogonal modulation signal;

[0032] The quadrature modulation signal is split into a tag receiving signal and a payload receiving signal.

[0033] The tag received signal and the payload received signal are demodulated to recover the tag signal and the payload signal.

[0034] Preferably, the method for demodulating the tag received signal to recover the tag signal includes:

[0035] The received signal from the tag is filtered to obtain an optical signal carrying the DPSK tag signal;

[0036] The optical signal obtained after filtering by the first low-pass filter is subjected to interference superposition to obtain the optical signal after interference superposition.

[0037] The optical signal after interference superposition is converted into an electrical signal to recover the tag signal.

[0038] A modulation and demodulation apparatus, the apparatus comprising:

[0039] The modulation module is used to use the pseudo-random binary encoded data after DPSK modulation as the tag signal, and the inverted 5B8B code data after software encoding as the payload signal. The payload signal and the tag signal are used to modulate the optical carrier to obtain an orthogonal modulation signal, and the orthogonal modulation signal is output.

[0040] The demodulation module is used to split the received quadrature modulation signal into a tag receiving signal and a payload receiving signal, demodulate the tag receiving signal and the payload receiving signal, and recover the tag signal and the payload signal.

[0041] The beneficial technical effects of this invention include: employing an optical tag switching system, method, and device based on inverted 5B8B codes, by introducing simple and low-cost line coding technology into optical tag switching and combining it with an orthogonal modulation scheme, the spectral utilization efficiency of the optical tag channel is improved while reducing crosstalk between the payload signal and the tag signal, thereby increasing network throughput; by creatively proposing an inverted 5B8B code for ASK modulation in orthogonal modulation-based optical tag switching, compared with the Manchester code and PPM code used in the prior art, the inverted 5B8B code has a coding efficiency 12.5% ​​higher and a tagging rate of 75%-87.5%. The high tagging rate provides more tags to carry phase information and enhances one-bit delay interference, thereby increasing the probability of successful DPSK demodulation, significantly reducing the limitation of extinction ratio on ASK modulation, and thus improving the quality of the ASK payload signal; compared with the inverted 4PPM code used in the prior art, the inverted 5B8B code can suppress low-frequency components and reduce crosstalk generated from high-speed ASK payload signals to low-speed DPSK signals.

[0042] Other features and advantages of the present invention will be disclosed in detail in the following detailed description and accompanying drawings. Attached Figure Description

[0043] The invention will be further described below with reference to the accompanying drawings:

[0044] Figure 1 This is a schematic diagram of the optical tag switching system based on the inverted 5B8B code according to an embodiment of the present invention.

[0045] Figure 2 This is a schematic diagram of the structure of the tag receiving signal demodulation unit in an embodiment of the present invention.

[0046] Figure 3 This is a schematic diagram of the structure of the payload receiving signal demodulation unit in an embodiment of the present invention.

[0047] Figure 4 This is a schematic diagram of the demodulation results of the DPSK and ASK signals when the extinction ratios are 5dB, 10dB, and 14dB, respectively.

[0048] Figure 5a , 5b Figure 5c shows the bit error rate test results of the DPSK and ASK signals with extinction ratios of 5dB, 10dB, and 14dB, respectively.

[0049] Figure 6a This is a schematic diagram of the receiver sensitivity-extinction ratio test results for 5Gb / s DPSK and 40Gb / s ASK signals.

[0050] Figure 6bThis is a schematic diagram of the receiver sensitivity-extinction ratio test results for 2.5Gb / s DPSK and 40Gb / s ASK signals.

[0051] Figure 7 This is a flowchart of an embodiment of the optical tag switching method based on inverted 5B8B code according to an embodiment of the present invention.

[0052] Figure 8 This is a flowchart of a method for demodulating the received signal of a tag to recover the tag signal according to an embodiment of the present invention.

[0053] Figure 9 This is a schematic diagram of a modulation and demodulation device according to an embodiment of the present invention.

[0054] The components are: 1. Signal generation module, 2. Parallel modulator, 3. Coupler, 4. Signal receiving module, 5. First low-pass filter, 6. Delay interferometer, 7. First photodetector, 8. First signal receiver, 9. Second low-pass filter, 10. Second photodetector, 11. Second signal receiver, 12. Modulation module, and 13. Demodulation module. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0056] In the following description, terms such as “inner,” “outer,” “upper,” “lower,” “left,” and “right” are used only to indicate orientation or positional relationship for the convenience of describing the embodiments and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0057] Before describing the technical solution of this embodiment in detail, the background of the application of this embodiment will be introduced first.

[0058] Communication systems based on digital electronic node switching technology have reached near-limits in electronic device processing capabilities. Further increasing processing speed will only exponentially increase the difficulty. The development of electronic technology has lagged far behind the growth rate of communication capacity, leading to bandwidth limitations and electronic bottlenecks in switching systems. Currently, there is a need to increase link bandwidth and node throughput to cope with the surge in network traffic. However, most switching nodes still use electrical switching, which severely limits processing speed and energy consumption—the current network bottleneck. All-optical packet switching (AOLS), which uses optical methods to forward information, is still in the research stage. AOLS is considered a representative technology for next-generation ultra-high-speed, low-power, high-bandwidth optical networks. However, many components required for AOLS, such as optical storage and optical logic devices, are still immature. Therefore, researchers have ultimately focused on a compromise solution between electrical switching and all-optical switching—Optical Label Switching (OLS).

[0059] Optical tag switching (OTS) technology writes routing information into low-speed tag signals and data information into high-speed payload signals. At the switching node, the optical tag signal is converted to the electrical domain for processing, while the payload signal continues to be transmitted in the optical domain, achieving all-optical transmission of the payload signal. Based on the routing information attached to the low-speed tag signal extracted at the node, the payload is output to the corresponding output port through the switching structure within the node. This separates the tag and payload, allowing intermediate nodes to use only inexpensive, low-speed tag photoelectric receiving systems, avoiding the expensive photoelectric-optical (OEO) conversion of high-speed data. This significantly reduces costs and greatly saves node energy consumption and packet switching processing time, minimizing tag processing of data packets and simplifying network control. Especially when there are a large number of intermediate nodes, network efficiency, scalability, and throughput are all improved.

[0060] Optical tag switching (OTS) technology has attracted much attention in recent years, and many OTS technical solutions have been proposed. Among these methods, quadrature modulation (QM) is widely used. QM superimposes a non-amplitude modulated signal onto an amplitude shift keying (ASK) signal. Because the tag uses non-amplitude modulation in QM, it can be directly superimposed on the payload without requiring additional time slots or wavelength channels. Simultaneously, tag and payload separation can be achieved through appropriate receivers. Common QM types include: Quadrature Amplitude Modulation (QAM), Orthogonal Frequency Division Multiplexing (OFDM), Coordinated Orthogonal Frequency Division Multiplexing (COFDM), Interleaved Quadrature Quadrature Phase Shift Keying (OQPSK), and π / 4-DQPSK. In QM, the non-amplitude modulated tag signal is subject to crosstalk due to amplitude fluctuations caused by ASK modulation. Therefore, in order to reduce this crosstalk, ASK payload signals are usually smoothed by reducing the extinction ratio or changing the code pattern (Manchester code and PPM code are commonly used). However, reducing the extinction ratio (ER) of the ASK payload signal also deteriorates the quality of the ASK payload signal.

[0061] In optical tag switching technology, the non-amplitude modulation of tag signals mainly includes three methods: Frequency Shift Keying (FSK), Differential Phase Shift Keying (DPSK), and Polarization Shift Keying (PolSK). However, because PolSK is sensitive to polarization rotation angle, and FSK occupies more wavelength resources and suffers from more dispersion, DPSK is the most widely used of the three modulation methods. The DPSK modulator is a LiNbO3 (lithium niobate) phase modulator, and the DPSK demodulator is a delay interferometer (DI). The delay interferometer (DI) interferes and superimposes the DPSK signal with its own one-bit delay, and since the signal itself becomes the reference beam, a local oscillator is not required. This simple and low-cost operation makes DPSK the most widely used non-amplitude modulation method in optical communication.

[0062] DPSK uses a one-bit delay for interferometric demodulation, which requires the delayed data to coincide with the original signal marker position, i.e., the "1" amplitude bit of the ASK. However, ASK modulation with a high extinction ratio often results in misalignment of the marker bits, making demodulation impossible and significantly reducing the demodulation performance of DPSK. Therefore, the extinction ratio of ASK modulation must be reduced. However, while reducing the extinction ratio improves the demodulated DPSK signal, it degrades the quality of the ASK load signal.

[0063] Therefore, it is necessary to study an optical tag switching method that can improve the spectral utilization efficiency of optical tag channels, reduce the impact on the quality of payload signals, and reduce crosstalk between payload signals and tag signals.

[0064] Therefore, this application provides an optical tag switching system based on inverted 5B8B codes to realize the switching of optical tag signals using pseudo-random binary data. Please refer to the appendix. Figure 1 ,include:

[0065] Signal generation module 1 is used to generate tag signals and load signals, and output the tag signals and load signals to parallel modulator 2.

[0066] Parallel modulator 2 is used to modulate the optical carrier using the load signal and tag signal output by signal generation module 1 to obtain an orthogonal modulated signal, and output the orthogonal modulated signal;

[0067] Coupler 3 is used to split the quadrature modulation signal into a tag receiving signal and a payload receiving signal;

[0068] The signal receiving module 4 is used to demodulate the tag receiving signal and the payload receiving signal to recover the tag signal and the payload signal.

[0069] On the other hand, in this embodiment, the tag signal generated by the signal generation module 1 is pseudo-random binary data after DPSK modulation, and the payload signal generated by the signal generation module 1 is inverted 5B8B code data.

[0070] Pseudo-random binary signals have wide applications in modern engineering practice, including mobile communication, navigation, radar, secure communication, and the measurement of communication system performance. For example, they can be used as ranging signals in continuous wave radar, as remote control signals in remote control systems, as address signals in multiple access communication, as group synchronization signals in digital communication, as noise sources, and for encryption in secure communication. The application of pseudo-random generators in ranging and communication is receiving increasing attention. The difference between pseudo-random binary data and random binary data is that random binary data is unpredictable; its future value can only be described statistically. Pseudo-random binary data, on the other hand, is not actually random; it is deterministic periodic data known to both the sender and receiver. It is called pseudo-random binary data because it exhibits the statistical characteristics of white noise sampling data, appearing to an observer unaware of its generation method as truly random binary data.

[0071] DPSK uses a one-bit delay for interference demodulation, which requires the one-bit delayed data to coincide with the original signal marker position, i.e., the amplitude bit of the "1" in ASK. However, ASK modulation with a high extinction ratio often results in misalignment of the marker bits, making demodulation impossible and significantly reducing the demodulation performance of DPSK. Therefore, the extinction ratio of ASK modulation must be reduced. However, while reducing the extinction ratio improves the demodulated DPSK signal, it degrades the quality of the ASK payload signal. To address this, this embodiment creatively proposes an inverted 5B8B code for ASK modulation in orthogonal modulation-based optical tag switching. Compared to the Manchester code and PPM code used in existing technologies, the inverted 5B8B code has a coding efficiency 12.5% ​​higher and a marker rate of 75%–87.5%. The high marker rate provides more markers to carry phase information and enhances the one-bit delay interference, thereby increasing the probability of successful DPSK demodulation, significantly reducing the limitation of the extinction ratio on ASK modulation, and thus improving the quality of the ASK payload signal. Meanwhile, compared to the inverted 4PPM code used in existing technologies, the inverted 5B8B code can suppress low-frequency components and reduce crosstalk generated from high-speed ASK load signals to low-speed DPSK signals.

[0072] On the other hand, in this embodiment, the parallel modulator 2 includes:

[0073] A phase modulator is used to perform DPSK modulation on an optical carrier using the tag signal generated by the signal generation module 1.

[0074] A Mach-Zehnder modulator is used to perform ASK modulation on an optical carrier using the load signal generated by the signal generation module 1.

[0075] On the other hand, in this embodiment, the quadrature modulation signal output by the parallel modulator 2 is transmitted to the coupler 3 via a single-mode fiber, a dispersion compensation fiber, and an adjustable optical attenuator.

[0076] Single-mode fiber is an optical fiber with a very thin central glass core (typically 9 or 10 μm in diameter) and only one transmission mode. It is widely used in communication systems, especially high-capacity systems. Single-mode fiber has relatively low transmission loss and dispersion, allowing signals to travel longer distances within the fiber. Low dispersion is also beneficial for high-speed, high-capacity data transmission. Dispersion-compensating fiber (DCF) is an optical fiber with large negative dispersion. It is a new type of single-mode fiber designed to address the limitations of the currently deployed G652 standard single-mode fiber. The dispersion of G652 standard single-mode fiber at a wavelength of 1.55μm is not zero, but positive (17-20) ps / (nm·km) and has a positive dispersion slope. Therefore, in order to enable the currently deployed G652 standard single-mode fiber system to adopt WDM / EDFA technology, it is necessary to add dispersion compensation fiber with negative dispersion to these fibers to perform dispersion compensation, so as to ensure that the total dispersion of the entire fiber line is approximately zero, thereby realizing high-speed, high-capacity, and long-distance communication.

[0077] The adjustable optical attenuator is used to measure the bit error rate.

[0078] On the other hand, in this embodiment, the signal receiving module 4 includes:

[0079] The tag receiving signal demodulation unit is used to demodulate the tag receiving signal and recover the tag signal;

[0080] The load receiving signal demodulation unit is used to demodulate the load receiving signal and recover the load signal.

[0081] On the other hand, in this embodiment, please refer to the appendix. Figure 2 The tag receiving signal demodulation unit includes:

[0082] The first low-pass filter 5 is used to filter the received signal of the tag to obtain an optical signal carrying the DPSK tag signal;

[0083] The delay interferometer 6 is used to perform interference superposition on the optical signal obtained after filtering by the first low-pass filter 5, and to obtain the superimposed optical signal and output it to the first photodetector 7.

[0084] The first photodetector 7 is used to convert the optical signal after interference superposition into an electrical signal, recover the tag signal, and output the recovered tag signal to the first signal receiving terminal 8;

[0085] The first signal receiving terminal 8 is used to receive the tag signal recovered by the first photodetector 7.

[0086] The DPSK modulator is a LiNbO3 (lithium niobate) phase modulator, and the DPSK demodulator is a delay interferometer 6 (DI). The delay interferometer 6 (DI) interferes and superimposes the DPSK signal with its own one-bit delay, and since the signal itself serves as the reference beam, a local oscillator is not required. This simple and low-cost operation makes DPSK the most widely used non-amplitude modulation method in optical communication.

[0087] On the other hand, in this embodiment, please refer to the appendix. Figure 3 The payload receiving signal demodulation unit includes:

[0088] The second low-pass filter 9 is used to filter the received load signal to obtain an optical signal carrying the ASK load signal.

[0089] The second photodetector 10 is used to convert the optical signal obtained after filtering by the second low-pass filter 9 into an electrical signal and recover the load signal.

[0090] The second signal receiving terminal 11 is used to receive the load signal recovered by the second photodetector 10.

[0091] For example, the implementation of the optical tag switching system based on the inverted 5B8B code in this embodiment is as follows:

[0092] The optical carrier first uses a 2.5Gb / s tag signal to perform DPSK modulation by a phase modulator, and then uses a 40Gb / s payload signal to perform ASK modulation by a Mach-Zehnder modulator; the modulated tag signal and payload signal are superimposed to obtain an orthogonal modulated signal;

[0093] The quadrature modulated signal is transmitted over a 50km single-mode fiber, a 10km dispersion-compensated fiber, and an adjustable optical attenuator.

[0094] The transmitted quadrature modulation signal is split using a 1:1 coupler 3, which divides the quadrature modulation signal into a tag receiving signal and a payload receiving signal.

[0095] After the tag-received signal is filtered by the first low-pass filter 5 and superimposed by the delay interferometer 6, the first photodetector 7 performs analog-to-digital conversion to convert the optical signal into an electrical signal. The converted electrical signals are then combined and decoded to recover the tag signal. After the load-received signal is filtered by the second low-pass filter 9, the second photodetector 10 performs analog-to-digital conversion to convert the optical signal into an electrical signal. The converted electrical signals are then combined and decoded to recover the load signal.

[0096] The effects of this invention can be further illustrated by the following simulation experiments:

[0097] 1) Simulation conditions:

[0098] Simulation experiments were conducted using a tag signal modulated by DPSK at 2.5 Gb / s and a payload signal modulated by ASK at 40 Gb / s.

[0099] 2) Simulation content and result analysis:

[0100] Simulation 1: In this simulation experiment, the payload signal is encoded using NRZ, Manchester code, inverted 4PPM code, and inverted 5B8B code, respectively. The tag and payload signals are demodulated when the extinction ratios are 5dB, 10dB, and 14dB, respectively. Please refer to the appendix for the eye diagrams of the demodulation results. Figure 4 .

[0101] As the extinction ratio increases, the quality of the demodulated DPSK signal gradually decreases, while the quality of the ASK signal gradually improves. Among the DPSK signals, the DPSK signal added to the ASK signal based on NRZ encoding exhibits the worst performance, while the DPSK signal added to the inverted 4PPM code exhibits the best performance. The performance of the DPSK signal added to the ASK signal based on inverted 5B8B code encoding proposed in this embodiment is not significantly different from that of the inverted 4PPM code, but the inverted 5B8B code has higher encoding efficiency. The performance difference of the DPSK signal added to the ASK signal based on different code types increases with the increase of the extinction ratio. The DPSK signal added to NRZ will be destroyed by a high ER extinction ratio. When the extinction ratio increases to 14dB, the quality of the DPSK signal added to the Manchester code deteriorates significantly, but the quality degradation of the DPSK signal added to the ASK signal based on inverted 5B8B code encoding proposed in this embodiment is not significant. Simulation results show that the DPSK signal added to the ASK signal based on inverted 5B8B code encoding proposed in this embodiment can tolerate a higher extinction ratio, which will significantly reduce the limitation of the extinction ratio on ASK modulation and thus improve the quality of the ASK load signal.

[0102] Simulation 2: In this simulation experiment, the payload signal was encoded using NRZ, Manchester code (MC), inverted 4PPM code, and inverted 5B8B code, respectively. The bit error rate (BER) of the tag signal and payload signal was tested when the extinction ratios were 5dB, 10dB, and 14dB, respectively. Please refer to the attached diagram for the BER results. Figure 5a , 5b And 5c.

[0103] Comparison Appendix Figure 5a , 5bIn the 5c model, ASK payload signals based on different code patterns (dashed lines in the figure) show that NRZ exhibits better performance, while inverted 4PPM code and inverted 5B8B code exhibit worse performance. The performance difference is mainly due to the different tag ratios of the payload signals based on different code patterns. The tag ratios for Manchester code and NRZ signals are both 50%, while the tag ratios for inverted 4PPM code signals are 75%, and for inverted 5B8B code signals, they are 75% or 87.5%. Signals with lower tag ratios also have relatively lower received power, resulting in better receiver sensitivity and thus better performance. Although both NRZ and Manchester code signals have a tag ratio of 50%, the NRZ signal exhibits better performance due to its narrower bandwidth.

[0104] Comparison Appendix Figure 5a , 5b The DPSK signal (solid line in the figure) added to the ASK payload signal based on different code patterns in 5c, and the DPSK signal added to the ASK signal based on the inverted 5B8B code proposed in this embodiment, can still achieve a bit error rate of 10 even when the extinction ratio is 14dB. -9 .

[0105] Simulation 3: In this simulation experiment, the payload signal was encoded using NRZ, Manchester code, inverted 4PPM code, and inverted 5B8B code, respectively. The receiver sensitivity-extinction ratio was tested for the 5Gb / s tag signal modulated by DPSK and the 40Gb / s payload signal modulated by ASK. The receiver sensitivity is defined as the bit error rate reaching 10^-5. -9 For the received power at that time, please refer to the attached document for the test results. Figure 6a .

[0106] According to the appendix Figure 6a Simulation results show that the optimal extinction ratio is 4.2dB for DPSK modulation added to NRZ; 8.5dB for DPSK modulation added to Manchester code; 8dB for DPSK modulation added to inverted 4PPM; and 7.2dB for DPSK modulation added to inverted 5B8B code.

[0107] In this simulation experiment, the payload signal was encoded using NRZ, Manchester code, inverted 4PPM code, and inverted 5B8B code, respectively. The receiver sensitivity-extinction ratio was tested for the tag signal modulated by DPSK at 2.5Gb / s and the payload signal modulated by ASK at 40Gb / s. The receiver sensitivity is defined as the bit error rate reaching 10^-5. -9 For the received power at that time, please refer to the attached document for the test results. Figure 6b .

[0108] According to the appendix Figure 6bSimulation results show that the optimal extinction ratio for DPSK modulation added to NRZ is 6dB. When the ASK signal is changed to Manchester code, the optimal extinction ratio increases to 12.2dB. When the inverted 4PPM and the inverted 5B8B code proposed in this embodiment are applied to the ASK signal, their optimal extinction ratios are not significantly different, almost reaching 14dB. When the ASK signals encoded with different code types are at their optimal extinction ratios, the receiver sensitivities of DPSK modulation added to NRZ, Manchester code, inverted 4PPM, and inverted 5B8B code are -16dBm, -17.8dBm, -20.3dBm, and -20.2dBm, respectively. Compared to DPSK modulation added to NRZ, the receiver sensitivity of DPSK modulation added to the inverted 5B8B code proposed in this embodiment is improved by 4.2dBm. Furthermore, the tagging rate of inverted 4PPM is 75%, while that of inverted 5B8B code can reach 87.5%. It can be seen that, when the receiving sensitivity is not much different, the coding efficiency of the inverted 5B8B code signal proposed in this embodiment is higher.

[0109] Comparison Appendix Figure 6a With appendix Figure 6b In this embodiment, it is more effective to use a tag signal modulated by DPSK at 2.5Gb / s and a payload signal modulated by ASK at 40Gb / s for simulation experiments.

[0110] On the other hand, embodiments of this application also provide an optical tag switching method based on inverted 5B8B codes, used to realize optical tag signal switching of pseudo-random binary data. Please refer to the appendix. Figure 7 This includes the following steps:

[0111] Step A01) Generate inverted 5B8B code data, use the inverted 5B8B code data as the payload signal, and use the pseudo-random binary data modulated by DPSK as the tag signal.

[0112] The 5B encoding scheme divides the data stream to be sent into groups of 4 bits, and then converts each 4-bit binary code into a corresponding 5-bit code according to the 5B encoding rules. There are 32 possible combinations of these 5-bit codes, but only 16 of them are used, and the other 16 are used as control codes to indicate the start and end of frames, the status of fiber optic lines (stationary, idle, paused), etc.

[0113] Preferably, in this embodiment, the inverted 5B8B code is generated as follows: a 5-bit code is mapped to an 8-bit code, which has either two "1"s or one "1"; selecting 32 "1"s yields the encoded 5B8B code. Then, the encoded 5B8B code is inverted to obtain the inverted 5B8B code. The tag signal is generated by inputting pseudo-random binary data into a phase modulator for DPSK modulation.

[0114] Step A02) Modulate the optical carrier using the load signal and the tag signal to obtain an orthogonal modulation signal.

[0115] Step A03) The quadrature modulation signal is split into tag receiving signal and payload receiving signal.

[0116] Step A04) Demodulate the tag received signal and the payload received signal to recover the tag signal and the payload signal.

[0117] On the other hand, in this embodiment, please refer to the appendix. Figure 8 The method for demodulating the received signal from the tag and recovering the tag signal includes:

[0118] Step B01) Filter the received signal of the tag to obtain an optical signal carrying the DPSK tag signal;

[0119] Step B02) The optical signal obtained after filtering by the first low-pass filter 5 is subjected to interference superposition to obtain the optical signal after interference superposition;

[0120] Step B03) Convert the optical signal after interference superposition into an electrical signal to recover the tag signal.

[0121] It should be noted that the implementation of the optical tag switching method based on the inverted 5B8B code is similar to that of the optical tag switching system based on the inverted 5B8B code, and will not be described again in this embodiment.

[0122] On the other hand, embodiments of this application also provide a modulation and demodulation device, please refer to the appendix. Figure 9 The device includes:

[0123] The modulation module 12 is used to use the pseudo-random binary encoded data after DPSK modulation as the tag signal, and the inverted 5B8B code data after software encoding as the payload signal. The payload signal and the tag signal are used to modulate the optical carrier to obtain an orthogonal modulation signal, and the orthogonal modulation signal is output.

[0124] The demodulation module 13 is used to split the received quadrature modulation signal into a tag receiving signal and a payload receiving signal, demodulate the tag receiving signal and the payload receiving signal, and recover the tag signal and the payload signal.

[0125] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. An optical tag switching system based on inverted 5B8B code, used to realize the switching of optical tag signals of pseudo-random binary data, characterized in that, include: A signal generation module is used to generate tag signals and payload signals, and output the tag signals and payload signals to a parallel modulator; A parallel modulator is used to modulate an optical carrier using the payload signal and tag signal output by the signal generation module to obtain an orthogonal modulated signal, and output the orthogonal modulated signal. A coupler is used to split the quadrature modulation signal into a tag receiving signal and a payload receiving signal; The signal receiving module is used to demodulate the tag received signal and the payload received signal to recover the tag signal and the payload signal; Among them, the tag signal generated by the signal generation module is pseudo-random binary data after DPSK modulation, and the payload signal generated by the signal generation module is inverted 5B8B code data. The parallel modulator includes: A phase modulator is used to perform DPSK modulation on an optical carrier using a tag signal generated by the signal generation module; A Mach-Zehnder modulator is used to perform ASK modulation on an optical carrier using a load signal generated by the signal generation module.

2. The optical tag switching system based on inverted 5B8B code as described in claim 1, characterized in that, The orthogonal modulation signal output by the parallel modulator is transmitted to the coupler via a single-mode fiber, a dispersion-compensating fiber, and a tunable optical attenuator.

3. The optical tag switching system based on inverted 5B8B code as described in claim 1, characterized in that, The signal receiving module includes: The tag receiving signal demodulation unit is used to demodulate the tag receiving signal and recover the tag signal; The load receiving signal demodulation unit is used to demodulate the load receiving signal and recover the load signal.

4. The optical tag switching system based on inverted 5B8B code as described in claim 3, characterized in that, The tag receiving signal demodulation unit includes: A first low-pass filter is used to filter the received signal of the tag to obtain an optical signal carrying the DPSK tag signal; The delay interferometer is used to perform interference superposition on the optical signal obtained after filtering by the first low-pass filter, and to obtain the superimposed optical signal and output it to the first photodetector. The first photodetector is used to convert the optical signal after interference superposition into an electrical signal, recover the tag signal, and output the recovered tag signal to the first signal receiving end; The first signal receiving end is used to receive the tag signal recovered by the first photodetector.

5. The optical tag switching system based on inverted 5B8B code as described in claim 3, characterized in that, The payload receiving signal demodulation unit includes: A second low-pass filter is used to filter the received signal of the payload to obtain an optical signal carrying the ASK payload signal; The second photodetector is used to convert the optical signal obtained after filtering by the second low-pass filter into an electrical signal to recover the load signal. The second signal receiving end is used to receive the load signal recovered by the second photodetector.

6. A method for switching optical tags based on inverted 5B8B codes, used to realize the switching of optical tag signals with pseudo-random binary data, characterized in that, Includes the following steps: Generate inverted 5B8B code data, use the inverted 5B8B code data as the payload signal, and use the pseudo-random binary data modulated by DPSK as the tag signal. The optical carrier is modulated using the payload signal and the tag signal to obtain an orthogonal modulation signal; The quadrature modulation signal is split into a tag receiving signal and a payload receiving signal. The tag received signal and the payload received signal are demodulated to recover the tag signal and the payload signal; The process of modulating the optical carrier using the payload signal and the tag signal includes: The optical carrier is modulated using the tag signal using DPSK modulation. The optical carrier is modulated using a load signal.

7. The optical tag switching method based on inverted 5B8B code as described in claim 6, characterized in that, include: The method for demodulating the received signal from the tag and recovering the tag signal includes: The received signal from the tag is filtered to obtain an optical signal carrying the DPSK tag signal; The filtered optical signal is subjected to interference superposition to obtain the superimposed optical signal. The optical signal after interference superposition is converted into an electrical signal to recover the tag signal.

8. A modulation and demodulation device, characterized in that, The device includes: The modulation module is used to use the pseudo-random binary encoded data after DPSK modulation as the tag signal, and the inverted 5B8B code data after software encoding as the payload signal. The payload signal and the tag signal are used to modulate the optical carrier to obtain an orthogonal modulation signal, and the orthogonal modulation signal is output. The demodulation module is used to split the received quadrature modulation signal into a tag receiving signal and a payload receiving signal, demodulate the tag receiving signal and the payload receiving signal, and recover the tag signal and the payload signal. The modulation module includes: A phase modulator is used to perform DPSK modulation on an optical carrier using a tag signal; Mach-Zehnder modulators are used to perform ASK modulation on optical carriers using a load signal.

Images