Optical label switching system and method based on new type of code shift keying label stack

Abstract

This invention relates to the field of communication technology, specifically to an optical tag switching system and method based on novel code shift keying (CPS) tag overlay. The system includes: a CPS signal loading module for loading a CPS tag signal onto a clock signal to generate a tag clock signal, and outputting the tag clock signal to a modulation module; a payload signal loading module for generating a payload signal and outputting the payload signal to the modulation module; a modulation module for overlaying the tag clock signal output by the CPS signal loading module onto the payload signal output by the payload signal loading module, using the overlaid optical packet signal to modulate the optical carrier, generating a combined signal, and outputting the combined signal; and a demodulation module for demodulating the combined signal output by the modulation module to recover the CPS tag signal and the payload signal. The beneficial technical effects of this invention include: improving the coding efficiency during tag overlay in optical tag switching.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and specifically to an optical tag switching system and method based on novel code shift keying tag overlay. Background Technology

[0002] With the rapid growth of packet traffic and data exchange demands in networks and data centers, optical packet switching has been proposed as a technology to improve network bandwidth resource utilization. In optical packet switching, data is packaged into optical packets, and the tag in the packet is transmitted along with the packaged data (called the payload). Typically, the tag and payload are combined at the network layer (such as IP protocol) or data link layer (such as Ethernet). However, in optical packet switching technology, even if most nodes (intermediate nodes) only need tag information to forward packets, each node still needs to receive the entire packet, including the tag and payload. Receiving the payload at each node is wasteful, especially in optical networks with transmission rates higher than 10Gb / s. Therefore, optical tag switching technology was proposed to separate the tag from the payload so that only the tag is read at intermediate nodes without detecting the payload. In each node of optical tag switching, a portion of the power of the optical packet is first extracted to a low-speed receiver for tag detection. If the packet has the same destination address as the node, the packet is sent to the payload receiver; otherwise, the packet is forwarded directly without passing through any other layer. Optical tag switching technology minimizes the transmission cost of packets and simplifies network control and management. Therefore, optical label switching technology improves network efficiency, scalability, and throughput, especially when there are a large number of intermediate nodes in the network.

[0003] In existing optical tag switching technologies, quadrature modulation (QMS) is widely used. QMS involves superimposing tag information onto the payload. Common QMS methods include Frequency Shift Keying (FSK), Phase Shift Keying (PSK), and Polarization Keying (PolSK). FSK, PSK, and PolSK are all non-amplitude modulation methods, and generally do not cause crosstalk to Amplitude Shift Keying (ASK) payload signals. However, amplitude fluctuations in FSK / PSK / PolSK signals caused by transmission dispersion can still lead to crosstalk in the ASK payload signal to some extent. Therefore, to reduce this crosstalk, ASK payload signals are typically smoothed by reducing the extinction ratio or changing the code pattern. Manchester code is commonly used to equalize the amplitude of ASK payload signals.

[0004] Although transmitting tag and payload signals together does not require additional time slots or wavelength channels, dual modulation increases cost and modulation loss. Currently, to reduce the operational complexity, modulation loss, and cost of dual modulation, existing technologies have proposed a tag-ratio modulation (MRM) method. In MRM, the payload signal is applied with a low tag-rate code pattern, and the tag signal is superimposed onto the payload by modulating its tag ratio. Subsequently, the payload and tag signals only need to be modulated by a single ASK modulation. However, due to the low coding efficiency of the low tag-rate code pattern, the effective transmission rate of the payload signal is affected; the coding efficiency of this method is only 50%. Furthermore, since the tag signal is ASK modulated, it cannot be altered at intermediate nodes.

[0005] Therefore, it is necessary to study an optical tag switching system or method that can improve the coding efficiency when tags are superimposed. Summary of the Invention

[0006] The technical problem to be solved by this invention is the low coding efficiency in current optical tag switching when tags are superimposed. This invention proposes an optical tag switching system and method based on a novel code shift keying (CPSK) tag superposition. By using the proposed novel CPSK for tag superposition, the coding efficiency reaches 100%, which is significantly higher than that of existing optical tag switching systems.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: an optical tag switching system based on novel code shift keying tag superposition, comprising:

[0008] The code shift keying signal loading module is used to load the code shift keying tag signal onto the clock signal to generate a tag clock signal, and output the tag clock signal to the modulation module;

[0009] A load signal loading module is used to generate a load signal and output the load signal to a modulation module;

[0010] The modulation module is used to superimpose the tag clock signal output by the code shift keying signal loading module onto the load signal output by the load signal loading module, use the superimposed optical packet signal to modulate the optical carrier, generate a combined signal, and output the combined signal.

[0011] The demodulation module is used to demodulate the combined signal output by the modulation module to recover the code shift keying tag signal and the payload signal.

[0012] Preferably, the modulation module includes:

[0013] A polarization controller is used to modulate the polarization state of the tag clock signal using a half-bit-rate clock signal;

[0014] An optical adder is used to superimpose the polarization-modulated tag clock signal and the payload signal to form an optical packet signal;

[0015] A phase modulator is used to phase modulate an optical carrier using an optical packet signal generated by the optical adder to produce a combined signal.

[0016] Preferably, the demodulation module includes:

[0017] A coupler is used to split the combined signal into a tag receiving signal and a payload receiving signal.

[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 combined signal is transmitted to the coupler via a single-mode fiber, a dispersion-compensating fiber, and an adjustable optical attenuator.

[0021] Preferably, the tag receiving signal demodulation unit includes:

[0022] A first low-pass filter is used to filter the received signal of the tag to obtain an optical signal carrying a code shift keying tag signal;

[0023] The first delay interferometer is used to perform interference superposition on the optical signal obtained after filtering by the first low-pass filter, wherein the delay difference of the interference superposition is half of the load signal, and the optical tag signal after interference superposition is obtained and output to the first photodetector.

[0024] The first photodetector is used to convert the optical tag signal into an electrical signal, recover the code shift keying tag signal, and output the recovered code shift keying tag signal to the first signal receiving end;

[0025] The first signal receiving end is used to receive the code shift keying tag signal recovered by the first photodetector.

[0026] Preferably, the payload receiving signal demodulation unit includes:

[0027] A second low-pass filter is used to filter the received signal of the payload to obtain an optical signal carrying the payload signal;

[0028] The second delay interferometer is used to perform interference superposition on the optical signal obtained after filtering by the second low-pass filter, wherein the delay of interference superposition is 2 bits, and the optical load signal after interference superposition is obtained and output to the second photodetector.

[0029] The second photodetector is used to convert the optical payload signal into an electrical signal, recover the payload signal, and output the recovered payload signal to the second signal receiving end;

[0030] The second signal receiving end is used to receive the load signal recovered by the second photodetector.

[0031] The optical tag switching method based on novel code shift keying tag superposition includes the following steps:

[0032] The code shift keying tag signal is loaded onto the clock signal to generate the tag clock signal;

[0033] A payload signal is generated, and the tag clock signal is superimposed on the payload signal. The superimposed optical packet signal is used to modulate the optical carrier to generate a combined signal.

[0034] The combined signal is demodulated to recover the code shift keying tag signal and the payload signal.

[0035] Preferably, the method of superimposing the tag clock signal onto the load signal includes:

[0036] The polarization state of the tag clock signal is modulated using a half-bit-rate clock signal;

[0037] The polarization-modulated tag clock signal is superimposed on the payload signal through an XOR operation to form an optical packet signal. After the XOR operation, when the tag clock signal is "1", the encoding form of the payload signal changes from NRZ code to Manchester code, and when the tag clock signal is "0", the encoding form of the payload signal changes from Manchester code to NRZ code.

[0038] Preferably, the method for demodulating the combined signal to recover the code shift keying tag signal includes:

[0039] The combined signal is split into a tag receiving signal and a payload receiving signal.

[0040] The received signal from the tag is filtered to obtain an optical signal carrying a code shift keying tag signal;

[0041] The optical signals are subjected to interference superposition, wherein the delay difference of the interference superposition is half of the load signal, to obtain the optical tag signal after interference superposition;

[0042] The optical tag signal is converted into an electrical signal to recover the code shift keying tag signal.

[0043] Preferably, the method for demodulating the combined signal to recover the load signal includes:

[0044] The combined signal is split into a tag receiving signal and a payload receiving signal.

[0045] The received payload signal is filtered to obtain an optical signal carrying the payload signal.

[0046] The optical signal is subjected to interference superposition, wherein the delay of interference superposition is 2 bits, to obtain the optical payload signal after interference superposition;

[0047] The optical payload signal is converted into an electrical signal to recover the payload signal.

[0048] The beneficial technical effects of this invention include: It employs a novel optical tag switching system and method based on code shift keying (CPSK) tag superposition, proposing a novel CPSK method for tag superposition. This method superimposes a tag signal with a modified encoding onto a payload signal. The superimposed optical packet signal simultaneously carries CPSK tag information and payload information, and is then modulated on an optical carrier. Since the payload signal is not encoded, decoding is unnecessary, achieving 100% encoding efficiency, significantly higher than existing optical tag switching methods. Phase modulation enables low modulation loss and balanced detection in optical tag switching. Polarization modulation adjusts the polarization states of adjacent bits of the tag clock signal to orthogonal states, avoiding potential crosstalk to the tag clock signal caused by constructive and destructive interference between the first and second halves of each bit during phase modulation of the optical packet signal.

[0049] Other features and advantages of the present invention will be disclosed in detail in the following detailed description and accompanying drawings. Attached Figure Description

[0050] The invention will be further described below with reference to the accompanying drawings:

[0051] Figure 1 This is a schematic diagram of the optical tag switching system based on the novel code shift keying tag superposition according to an embodiment of the present invention.

[0052] Figure 2 This is a schematic diagram of the modulation module in an embodiment of the present invention.

[0053] Figure 3 This is a schematic diagram of the structure of the tag receiving signal demodulation unit in an embodiment of the present invention.

[0054] Figure 4 This is a schematic diagram of the structure of the payload receiving signal demodulation unit in an embodiment of the present invention.

[0055] Figure 5a and5b This is an eye diagram of the load signal received in an embodiment of the present invention when the ratio of tag signal to load is 1:16 and 1:64, respectively.

[0056] Figure 6a , 6b 6c and 6d are eye diagrams of the code shift keying tag signals received in embodiments of the present invention when the ratio of tag signal to load is 1:8, 1:16, 1:32 and 1:64, respectively.

[0057] Figure 7a , 7b Figure 7c is a schematic diagram of the bit error rate test results of the code shift keying tag signal and the payload signal when the bit rate of the payload signal is 5Gb / s, 10Gb / s and 20Gb / s, respectively, according to an embodiment of the present invention.

[0058] Figure 8 This is a flowchart of an optical tag switching method based on novel code shift keying tag superposition, according to an embodiment of the present invention.

[0059] Figure 9 This is a flowchart of a method for recovering code shift keying tag signals according to an embodiment of the present invention.

[0060] Figure 10 This is a flowchart of a method for recovering the load signal according to an embodiment of the present invention.

[0061] The components are: 1. Code Shift Keying signal loading module, 2. Load signal loading module, 3. Modulation module, 4. Demodulation module, 5. Polarization controller, 6. Optical adder, 7. Phase modulator, 8. First low-pass filter, 9. First delay interferometer, 10. First photodetector, 11. First signal receiver, 12. Second low-pass filter, 13. Second delay interferometer, 14. Second photodetector, and 15. Second signal receiver. Detailed Implementation

[0062] 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.

[0063] 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.

[0064] This application provides an optical tag switching system based on a novel code shift keying tag overlay. Please refer to the appendix. Figure 1 ,include:

[0065] The code shift keying signal loading module 1 is used to load the code shift keying tag signal onto the clock signal to generate the tag clock signal, and output the tag clock signal to the modulation module 3.

[0066] The load signal loading module 2 is used to generate a load signal and output the load signal to the modulation module 3.

[0067] In this context, both the code shift keying tag signal and the payload signal are pseudo-random binary sequences. Pseudo-random binary sequences (PRBS) 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 sequences and random binary sequences is that random binary sequences are unpredictable, and their future values ​​can only be described statistically; while pseudo-random binary sequences are not actually random but are deterministic periodic sequences known to both the sender and receiver. They are called pseudo-random binary sequences because they exhibit the statistical characteristics of white noise sampling sequences, appearing to an observer unaware of their generation method as genuine random binary sequences.

[0068] The code shift keying signal loading module 1 and the load signal loading module 2 include, but are not limited to, a mode generator and a continuous wave laser.

[0069] The modulation module 3 is used to superimpose the tag clock signal output by the code shift keying signal loading module 1 onto the load signal output by the load signal loading module 2, and use the superimposed optical packet signal to modulate the optical carrier to generate a combined signal and output the combined signal.

[0070] Demodulation module 4 is used to demodulate the combined signal output by modulation module 3 to recover the code shift keying tag signal and the load signal.

[0071] This embodiment proposes a novel code shift keying (CPS) method for tag overlay. The tag signal, with a modified encoding format, is superimposed on the payload signal. The resulting optical packet signal carries both CPS tag information and payload information, and is then modulated on an optical carrier. Since the payload signal is not encoded, decoding is unnecessary, achieving 100% encoding efficiency, significantly higher than existing optical tag switching systems.

[0072] On the other hand, in this embodiment, the modulation module 3 includes:

[0073] Polarization controller 5 is used to modulate the polarization state of the tag clock signal using a half-bit rate clock signal;

[0074] Optical adder 6 is used to superimpose the polarization-modulated tag clock signal and the payload signal to form an optical packet signal;

[0075] Phase modulator 7 is used to phase modulate the optical carrier using the optical packet signal generated by optical adder 6 to produce a combined signal.

[0076] The tag clock signal is first connected to the polarization controller 5, and then to the optical adder 6, while the load signal is directly connected to the optical adder 6. The tag clock signal and the load signal are superimposed in the optical adder 6 to form an optical grouping signal.

[0077] For example, the specific implementation of the modulation module 3 is as follows: first, the polarization controller 5 modulates the polarization state of the tag clock signal using a half-bit rate clock signal; then, the optical adder 6 superimposes the polarization-modulated tag clock signal onto the payload signal through an XOR operation to form an optical packet signal. After the XOR operation, when the corresponding tag clock signal is "1" or "0", each unit of the optical packet signal is in NRZ format or Manchester code. Then, the optical packet signal is modulated onto a 1550nm optical carrier by the phase modulator 7 to generate a combined signal.

[0078] Phase modulation enables low modulation loss and balanced detection in optical tag switching. Simultaneously, polarization modulation adjusts the polarization states of adjacent bits of the tag clock signal to an orthogonal state, avoiding potential crosstalk to the tag clock signal caused by constructive and destructive interference between the first and second halves of each bit during phase modulation of the optical packet signal. Furthermore, since polarization modulation is only used to avoid interference between bits, polarization tracking and polarization separation are unnecessary.

[0079] On the other hand, in this embodiment, the demodulation module 4 includes:

[0080] A coupler is used to split a combined signal into a tag receiving signal and a payload receiving signal.

[0081] The tag receiving signal demodulation unit is used to demodulate the tag receiving signal and recover the tag signal;

[0082] The load receiving signal demodulation unit is used to demodulate the load receiving signal and recover the load signal.

[0083] On the other hand, in this embodiment, the combined signal is transmitted to the coupler via a single-mode fiber, a dispersion-compensating fiber, and a tunable optical attenuator.

[0084] For example, in a specific implementation of the combined signal transmission, the combined signal is transmitted to a coupler via a 50km single-mode fiber (SMF) and a dispersion-compensating fiber (DCF). An adjustable optical attenuator is used to measure the bit error rate.

[0085] On the other hand, in this embodiment, the tag receiving signal demodulation unit includes:

[0086] The first low-pass filter 8 is used to filter the tag received signal to obtain an optical signal carrying the code shift keying tag signal.

[0087] The first delay interferometer 9 is used to perform interference superposition on the optical signal obtained after filtering by the first low-pass filter 8, wherein the delay difference of the interference superposition is half of the load signal, and the optical tag signal after interference superposition is obtained and output to the first photodetector 10.

[0088] Optionally, the optical signal obtained after filtering the tag's received signal can be superimposed by a Mach-Zehnder delay interferometer (MZDI) with a delay difference that is half that of the load signal.

[0089] The first photodetector 10 is used to convert the optical tag signal into an electrical signal, recover the code shift keying tag signal, and output the recovered code shift keying tag signal to the first signal receiving terminal 11.

[0090] The first signal receiving end 11 is used to receive the code shift keying tag signal recovered by the first photodetector 10.

[0091] On the other hand, in this embodiment, the payload receiving signal demodulation unit includes:

[0092] The second low-pass filter 12 is used to filter the received load signal to obtain an optical signal carrying the load signal;

[0093] The second delay interferometer 13 is used to perform interference superposition on the optical signal obtained after filtering by the second low-pass filter 12, wherein the delay of interference superposition is 2 bits, and the optical load signal after interference superposition is obtained and output to the second photodetector 14.

[0094] The second photodetector 14 is used to convert the optical load signal into an electrical signal, recover the load signal, and output the recovered load signal to the second signal receiving terminal 15.

[0095] The second signal receiving terminal 15 is used to receive the load signal recovered by the second photodetector 14.

[0096] Since the polarization states of adjacent bits of the tag clock signal are orthogonal, the phase-modulated load signal needs to be demodulated by a 2-bit delay interference.

[0097] On the other hand, this application also provides a method for optical tag switching based on novel code shift keying tag superposition, including the following steps:

[0098] Step A01) Load the code shift keying tag signal onto the clock signal to generate the tag clock signal.

[0099] Step A02) Generate a payload signal and superimpose the tag clock signal onto the payload signal. Use the superimposed optical packet signal to modulate the optical carrier and generate a combined signal.

[0100] Among them, the code shift keying tag signal and the payload signal are both pseudo-random binary sequences.

[0101] For example, the specific implementation of generating the combined signal is as follows: two pseudo-random binary sequences are sent into an NRZ electrical pulse generator to generate optical packet signals, and then the optical packet signals are used as electrical input signals of the optical load and modulated onto the optical carrier by an optical amplitude modulator to form a combined signal.

[0102] Optionally, in this embodiment, the optical amplitude modulator that uses the superimposed optical group signal to modulate the optical carrier can be a Mach-Zehnder modulator with a common extinction ratio of 14dB.

[0103] Step A03) Demodulate the combined signal to recover the code shift keying tag signal and the load signal.

[0104] The coded tag signal is superimposed onto the payload signal, and the resulting optical packet signal carries both Code Shift Keying (CPSK) tag information and payload information. This signal is then modulated onto the optical carrier. Since the payload signal is not encoded, decoding is unnecessary, achieving 100% encoding efficiency, significantly higher than existing optical tag switching methods.

[0105] On the other hand, in this embodiment, the method of superimposing the tag clock signal onto the payload signal includes:

[0106] The polarization state of the tag clock signal is modulated using a half-bit-rate clock signal;

[0107] The polarization-modulated tag clock signal is superimposed on the payload signal through an XOR operation to form an optical packet signal. After the XOR operation, when the tag clock signal is "1", the encoding form of the payload signal changes from NRZ code to Manchester code, and when the tag clock signal is "0", the encoding form of the payload signal changes from Manchester code to NRZ code.

[0108] When the superimposed optical packet signal is phase-modulated using NRZ or Manchester code, the first and second halves of each bit will produce constructive or destructive interference. Constructive interference, also known as constructive interference, refers to the phenomenon where, in the superposition principle of light waves, if the crests (or troughs) of two light waves arrive at the same point simultaneously, the two light waves are said to be in phase at that point, and the interference wave will produce the largest amplitude. Destructive interference occurs when the optical path difference between two light waves is an odd multiple of half the wavelength. To avoid potential crosstalk to the tag clock signal caused by this constructive and destructive interference between the first and second halves of each bit, the polarization states of adjacent bits of the tag clock signal are adjusted to be orthogonal. Moreover, since polarization modulation is only used to avoid interference between bits, polarization tracking and polarization separation are unnecessary.

[0109] On the other hand, in this embodiment, the optical packet signal is first polarized multiplexed, and then the polarized multiplexed optical packet signal is used to modulate the optical carrier to generate a combined signal.

[0110] Polarization multiplexing (PM) refers to the use of the polarization dimension of light to transmit two independent data messages simultaneously through two mutually orthogonal polarization states of light in the same wavelength channel, thereby increasing the overall capacity of the system.

[0111] On the other hand, in this embodiment, the method for demodulating the combined signal and recovering the code shift keying tag signal includes:

[0112] Step B01) The combined signal is split into tag receiving signal and payload receiving signal;

[0113] Step B02) Filter the received signal of the tag to obtain the optical signal carrying the code shift keying tag signal;

[0114] Step B03) The optical signal is subjected to interference superposition, wherein the delay difference of the interference superposition is half of the load signal, and the optical tag signal after interference superposition is obtained.

[0115] Step B04) Convert the optical tag signal into an electrical signal to recover the code shift keying tag signal.

[0116] Optionally, at the receiving end, the code shift keying tag signals can be superimposed by a Mach-Zehnder delay interferometer (MZDI).

[0117] On the other hand, in this embodiment, the method for demodulating the combined signal and recovering the load signal includes:

[0118] Step C01) The combined signal is split into tag receiving signal and payload receiving signal.

[0119] Step C02) Filter the received load signal to obtain an optical signal carrying the load signal.

[0120] Step C03) The optical signal is subjected to interference superposition, wherein the delay of interference superposition is 2 bits, and the optical payload signal after interference superposition is obtained.

[0121] Since the polarization states of adjacent bits of the tag clock signal are orthogonal, the phase-modulated load signal needs to be demodulated by a 2-bit delay interference.

[0122] Step C04) Convert the optical load signal into an electrical signal to recover the load signal.

[0123] The effectiveness of this embodiment can be further illustrated by the following simulation experiments:

[0124] 1) Simulation conditions:

[0125] Both the code shift keying tag signal and the payload signal are pseudo-random binary sequences. Simulation experiments were conducted with payload signals at bit rates of 5Gb / s, 10Gb / s, and 20Gb / s. The rise and fall times were set to 5%, the extinction ratio was a common 14dB, and the generated code shift keying tag signal and payload signal were modulated onto a 1550nm carrier wave through phase modulator 7.

[0126] 2) Simulation content and result analysis:

[0127] Simulation 1: In this simulation experiment, the bit rate of the code shift keying tag signal is set to 1 / 16 and 1 / 64 of the bit rate of the payload signal, respectively. The eye diagram of the received payload signal is tested. The test results are shown in the appendix. Figure 5a and 5b .

[0128] According to the appendix Figure 5a and 5b Simulation results show that the performance of the payload signal remains almost unchanged when the covered code shift keying tag signals have different bit rates. This is because the payload signal is rarely affected by superimposed tag signals. In each unit of the optical packet signal, only two bits are Manchester code, while most bits are conventional NRZ code.

[0129] Simulation 2: In this simulation experiment, the bit rate of the Code Shift Keying (CSK) tag signal is set to 1 / 8, 1 / 16, 1 / 32, and 1 / 64 of the bit rate of the payload signal, respectively. The eye diagram of the received CSK tag signal is tested. The test results are shown in the appendix. Figure 6a , 6b6c and 6d.

[0130] According to the appendix Figure 6a , 6b Simulation results for 6c and 6d show that the code shift keying tag signal with a lower bit rate exhibits better performance because more of the amplitude fluctuation components in the payload unit of each optical packet signal are filtered by the low-pass filter.

[0131] Simulation 3: This embodiment tests the bit error rate (BER) of the code shift keying tag signal and the payload signal when the bit rate of the payload signal is 5Gb / s, 10Gb / s, and 20Gb / s, respectively. Please refer to the attached diagram for the BER results. Figure 7a , 7b And 7c.

[0132] The bit error rate (BER) curve for the code shift keying (CPSK) tag signal is represented by a dashed line, while the BER curve for the payload signal is represented by a solid line. When the ratio of the bit rate of the CPSK tag signal to the bit rate of the payload signal is 1:8, the corresponding BER curve is a square. When the ratio is 1:16, the corresponding BER curve is a solid sphere. When the ratio is 1:32, the corresponding BER curve is a triangle. When the ratio is 1:64, the corresponding BER curve is a star.

[0133] According to the appendix Figure 7a , 7b Simulation results for 7c show that the bit error rate curve of the payload signal remains almost unchanged because the payload signal is not affected by the superimposed Code Shift Keying (CSK) tag signal. When the bit rate ratio of the CSK tag signal to the payload signal is 1:8, 1:16, 1:32, and 1:64, respectively, the receiving sensitivity of the tag signal decreases by 1dB, 2.5dB, 4.2dB, and 6dB, respectively. This indicates that higher bit rates in the CSK tag signal exhibit poorer performance.

[0134] Meanwhile, optical packet signals composed of superimposed 5Gb / s, 10Gb / s, and 20Gb / s code shift keying tag signals can transmit over distances of 103.5km, 97.5km, and 88.5km, respectively, even without online amplification and pre-amplification.

[0135] In summary, the simulation results verify the feasibility of the optical tag switching system and method based on novel code shift keying tag superposition proposed in this embodiment.

[0136] 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 label switching system based on superposition of novel code shift keying labels, characterized by, include: The code shift keying signal loading module is used to load the code shift keying tag signal onto the clock signal to generate a tag clock signal, and output the tag clock signal to the modulation module; A load signal loading module is used to generate a load signal and output the load signal to a modulation module; The modulation module is used to superimpose the tag clock signal output by the code shift keying signal loading module onto the load signal output by the load signal loading module, use the superimposed optical packet signal to modulate the optical carrier, generate a combined signal, and output the combined signal. The demodulation module is used to demodulate the combined signal output by the modulation module to recover the code shift keying tag signal and the payload signal. The modulation module includes: A polarization controller is used to modulate the polarization state of the tag clock signal using a half-bit-rate clock signal; An optical adder is used to superimpose the polarization-modulated tag clock signal onto the payload signal through an XOR operation to form an optical group signal. After the XOR operation, when the tag clock signal is "1", the encoding form of the payload signal changes from NRZ code to Manchester code, and when the tag clock signal is "0", the encoding form of the payload signal changes from Manchester code to NRZ code. A phase modulator is used to phase modulate an optical carrier using an optical packet signal generated by the optical adder to produce a combined signal.

2. The optical tag switching system based on novel code shift keying tag superposition as described in claim 1, characterized in that, The demodulation module includes: A coupler is used to split the combined signal into a tag receiving signal and a payload receiving signal. 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.

3. The optical tag switching system based on novel code shift keying tag superposition as described in claim 2, characterized in that, The combined signal is transmitted to the coupler via a single-mode fiber, a dispersion-compensating fiber, and an adjustable optical attenuator.

4. The optical tag switching system based on novel code shift keying tag superposition as described in claim 2, 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 a code shift keying tag signal; The first delay interferometer is used to perform interference superposition on the optical signal obtained after filtering by the first low-pass filter, wherein the delay difference of the interference superposition is half of the load signal, and the optical tag signal after interference superposition is obtained and output to the first photodetector. The first photodetector is used to convert the optical tag signal into an electrical signal, recover the code shift keying tag signal, and output the recovered code shift keying tag signal to the first signal receiving end; The first signal receiving end is used to receive the code shift keying tag signal recovered by the first photodetector.

5. The optical tag switching system based on novel code shift keying tag superposition as described in claim 2, 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 payload signal; The second delay interferometer is used to perform interference superposition on the optical signal obtained after filtering by the second low-pass filter, wherein the delay of interference superposition is 2 bits, and the optical load signal after interference superposition is obtained and output to the second photodetector. The second photodetector is used to convert the optical payload signal into an electrical signal, recover the payload signal, and output the recovered payload signal to the second signal receiving end; The second signal receiving end is used to receive the load signal recovered by the second photodetector.

6. An optical label switching method based on a new type of code shift keying label stack, characterized by, Includes the following steps: The code shift keying tag signal is loaded onto the clock signal to generate the tag clock signal; A payload signal is generated, and the tag clock signal is superimposed on the payload signal. The superimposed optical packet signal is used to modulate the optical carrier to generate a combined signal. The combined signal is demodulated to recover the code shift keying tag signal and the payload signal; The method of superimposing the tag clock signal onto the load signal includes: The polarization state of the tag clock signal is modulated using a half-bit-rate clock signal; The polarization-modulated tag clock signal is superimposed on the payload signal through an XOR operation to form an optical packet signal. After the XOR operation, when the tag clock signal is "1", the encoding form of the payload signal changes from NRZ code to Manchester code, and when the tag clock signal is "0", the encoding form of the payload signal changes from Manchester code to NRZ code.

7. The optical tag switching method based on novel code shift keying tag superposition as described in claim 6, characterized in that, The method for demodulating the combined signal to recover the code shift keying tag signal includes: The combined signal is split into a tag receiving signal and a payload receiving signal. The received signal from the tag is filtered to obtain an optical signal carrying a code shift keying tag signal; The optical signals are subjected to interference superposition, wherein the delay difference of the interference superposition is half of the load signal, to obtain the optical tag signal after interference superposition; The optical tag signal is converted into an electrical signal to recover the code shift keying tag signal.

8. The optical tag switching method based on novel code shift keying tag superposition as described in claim 6, characterized in that, The method for demodulating the combined signal to recover the load signal includes: The combined signal is split into a tag receiving signal and a payload receiving signal. The received payload signal is filtered to obtain an optical signal carrying the payload signal. The optical signal is subjected to interference superposition, wherein the delay of interference superposition is 2 bits, to obtain the optical payload signal after interference superposition; The optical payload signal is converted into an electrical signal to recover the payload signal.

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