Signal transmission method and system

Abstract

This application relates to the field of single-fiber bidirectional signal transmission technology, and discloses a signal transmission method and system. The method, applied to a transmitter, includes: generating a double-sideband optical modulation signal based on optical and electrical signals; filtering and multiplexing the double-sideband optical modulation signal to generate a wavelength division multiplexing (WDM) single-sideband signal; and transmitting the WDM single-sideband signal to a receiver via an uplink or downlink transmission direction, so that the receiver filters and demultiplexes the WDM single-sideband signal to generate a restored electrical signal. This application can effectively reduce the number of high-performance filters and signal transmission loss.

Description

Technical Field

[0001] This application relates to the field of single-fiber bidirectional signal transmission technology, and in particular to signal transmission methods and systems. Background Technology

[0002] With the exponential growth of global internet traffic, current data center interconnects face unprecedented pressure to meet the demands for ultra-high capacity and ultra-low cost. Currently, data center interconnects primarily employ Intensity Modulation Direct Detection (IM / DD) schemes, but scaling up to meet ever-increasing capacity requirements is becoming increasingly challenging, mainly due to the low spectral efficiency of IM / DD and its susceptibility to fiber dispersion. For future 800G / 1.6T modules based on Four-Level Pulse Amplitude Modulation (PAM4) technology, line-side rates will reach over 200Gb / s / λ. Under these conditions, even with O-band transmission, the transmission distance of Coarse Wavelength Division Multiplexing (CWDM) is limited to within 4km, significantly restricting the application scope of IM / DD in data center interconnects. While coherent optical communication is technically an effective solution, cost considerations currently prevent its large-scale deployment in data center interconnects.

[0003] Single-sideband (SSB) modulation based on direct detection is currently an effective low-cost solution. By removing one redundant sideband, SSB signals can double the spectral efficiency compared to double-sideband (DSB) signals. Simultaneously, the narrow spectrum characteristic can reduce the impact of frequency-selective fading caused by dispersion in traditional IM / DD systems, thereby increasing transmission distance. There are typically three methods to achieve SSB modulation. Method 1: Direct optical filtering is used on the original DSB optical signal to remove either the upper or lower sideband, thus achieving SSB modulation. The main drawback of this method is its stringent filter requirements. When using wavelength division multiplexing (WDM), the cost increases linearly. Furthermore, when using non-tunable filters, system performance is affected by wavelength stability. Methods 2 and 3, one using an IQ modulator and the other using a dual-drive Mach-Zehnder modulator (MZM), share a similar modulation principle, both employing a Hilbert transform-based modulation scheme. The advantage of this scheme is that signal generation is unaffected by the laser, but the disadvantage is that it requires a new transmitter structure, making it incompatible with the existing system. This makes the cost of using it in a large-scale WDM system difficult to estimate and upgrades difficult to achieve. In large-scale data center optical interconnects, single-fiber bidirectional transmission technology is often used to save optical link resources, enabling bidirectional communication within the same optical fiber. This approach effectively increases the transmission capacity of single-fiber systems, meeting ever-increasing capacity demands while maintaining the original system structure. However, backscattering Rayleigh scattering is inevitable in single-fiber bidirectional systems. This noise reduces the signal-to-noise ratio (SNR) of the received signal, degrading the overall system performance. To avoid backscattering Rayleigh scattering, different wavelength uplink and downlink schemes are typically used in single-fiber bidirectional communication. The drawback of this method is that it uses more wavelength resources, resulting in high signal transmission loss and reduced system spectral efficiency.

[0004] Therefore, how to effectively reduce the number of high-performance filters and signal transmission loss is a problem that urgently needs to be solved.

[0005] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0006] The main objective of this application is to provide a signal transmission method and system that aims to solve the technical problem of how to effectively reduce the number of high-performance filters and signal transmission loss.

[0007] To achieve the above objectives, this application proposes a signal transmission method, which is applied to a transmitter, and the method includes:

[0008] Double-sideband optical modulation signals are generated based on optical and electrical signals;

[0009] The double-sideband optical modulation signal is filtered and combined to generate a wavelength division multiplexed single-sideband signal;

[0010] The wavelength division multiplexing single-sideband signal is transmitted to the receiver via the uplink or downlink transmission direction, so that the receiver can filter and demultiplex the wavelength division multiplexing single-sideband signal to generate the restored electrical signal.

[0011] In one embodiment, generating a double-sideband optical modulation signal based on optical and electrical signals includes:

[0012] Receives electrical and optical signals;

[0013] The electrical signal and the optical signal are modulated to generate a double-sideband optical modulation signal.

[0014] In one embodiment, the step of modulating the electrical signal and the optical signal to generate a double-sideband optical modulation signal includes:

[0015] The electrical signal and the optical signal are input to an intensity modulator, so that the intensity modulator loads the electrical signal onto the optical signal to generate a double-sideband optical modulation signal.

[0016] In one embodiment, filtering and multiplexing the double-sideband optical modulation signal to generate a wavelength division multiplexed single-sideband signal includes:

[0017] The double-sideband optical modulation signal is filtered to generate a single-sideband optical modulation signal;

[0018] The single-sideband optical modulation signal is combined to generate a wavelength division multiplexed single-sideband signal.

[0019] In one embodiment, the step of multiplexing the single-sideband optical modulation signal to generate a wavelength division multiplexed single-sideband signal includes:

[0020] The single-sideband optical modulation signal is amplified by equal gain to obtain an amplified single-sideband optical modulation signal.

[0021] The amplified single-sideband optical modulation signal is combined to generate a wavelength division multiplexed single-sideband signal.

[0022] In one embodiment, transmitting the wavelength division multiplexed single-sideband signal to the receiver via the uplink or downlink transmission direction includes:

[0023] When the wavelength division multiplexing single sideband signal is an upper sideband signal, the upper sideband signal is transmitted to the receiver through the uplink transmission direction;

[0024] When the wavelength division multiplexing single sideband signal is a lower sideband signal, the lower sideband signal is transmitted to the receiver through the downlink transmission direction.

[0025] Furthermore, to achieve the above objectives, this application also proposes a signal transmission method applied to a receiver, the method comprising:

[0026] Receive wavelength division multiplexed single-sideband signals transmitted by the transmitter;

[0027] The wavelength division multiplexed single-sideband signal is filtered and demultiplexed to generate the restored electrical signal.

[0028] In one embodiment, filtering and demultiplexing the wavelength division multiplexed single-sideband signal to generate the restored electrical signal includes:

[0029] The wavelength division multiplexed single-sideband signal is filtered and demultiplexed to generate the target single-sideband signal;

[0030] The target single-sideband signal is restored to generate a restored electrical signal.

[0031] In one embodiment, filtering and demultiplexing the wavelength division multiplexed single-sideband signal to generate the target single-sideband signal includes:

[0032] The wavelength division multiplexed single-sideband signal is filtered to obtain the filtered single-sideband signal.

[0033] The filtered single-sideband signal is then separated to generate the target single-sideband signal.

[0034] In one embodiment, the step of restoring the target single-sideband signal to generate a restored electrical signal includes:

[0035] The target single-sideband signal is sent to a photodetector, so that the photodetector performs photoelectric conversion on the target single-sideband signal to generate a restored electrical signal.

[0036] In addition, to achieve the above objectives, this application also proposes a signal transmission system, which includes a transmitter and a receiver, wherein the transmitter performs the signal transmission method as described above, and the receiver performs the signal transmission method as described above.

[0037] This application provides a signal transmission method applied to a transmitter. The method involves first generating a double-sideband optical modulation signal based on optical and electrical signals; then filtering and combining the double-sideband optical modulation signal to generate a wavelength division multiplexing (WDM) single-sideband signal; finally, transmitting the WDM single-sideband signal to a receiver via an uplink or downlink transmission direction. The receiver then filters and demultiplexes the WDM single-sideband signal to generate a restored electrical signal, effectively reducing the number of high-performance filters and signal transmission loss.

[0038] In summary, this application effectively improves the spectrum utilization by generating a double-sideband optical modulation signal based on optical and electrical signals. This allows for filtering and multiplexing of the double-sideband optical modulation signal, effectively reducing optical power loss. The generated wavelength division multiplexed single-sideband signal is then transmitted to a receiver via either the uplink or downlink direction for filtering and demultiplexing, achieving bidirectional signal transmission and electrical signal restoration. This overcomes the technical shortcomings of high-performance filter requirements and high signal transmission loss, effectively reducing the number of high-performance filters and signal transmission loss. Attached Figure Description

[0039] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0040] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart illustrating an embodiment of the signal transmission method applied to a transmitter in this application.

[0042] Figure 2 A frame diagram of a transmitter provided in Embodiment 1 of the signal transmission method applied to a transmitter according to this application;

[0043] Figure 3 This is a schematic diagram of wavelength division multiplexing single-sideband signal transmission provided in Embodiment 1 of the signal transmission method applied to a transmitter in this application;

[0044] Figure 4 This is a flowchart illustrating a second embodiment of the signal transmission method applied to a transmitter in this application.

[0045] Figure 5 This is a flowchart illustrating an embodiment of the signal transmission method applied to a receiver according to this application.

[0046] Figure 6 This is a flowchart illustrating a second embodiment of the signal transmission method applied to a receiver according to this application.

[0047] Figure 7 This is a frame diagram of a receiver provided in Embodiment 2 of the signal transmission method applied to a receiver according to this application.

[0048] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0049] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0050] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0051] The main solution of this application embodiment is: generating a double-sideband optical modulation signal based on optical and electrical signals; filtering and combining the double-sideband optical modulation signal to generate a wavelength division multiplexing (WDM) single-sideband signal; transmitting the WDM single-sideband signal to a receiver via an uplink or downlink transmission direction, so that the receiver filters and demultiplexes the WDM single-sideband signal to generate a restored electrical signal.

[0052] Single-sideband (SSB) modulation based on direct detection is currently an effective low-cost solution. By removing one redundant sideband, SSB signals can double the spectral efficiency compared to double-sideband (DSB) signals. Simultaneously, the narrow spectrum characteristic can reduce the impact of frequency-selective fading caused by dispersion in traditional IM / DD systems, thereby increasing transmission distance. There are typically three methods to achieve SSB modulation. Method 1: Direct optical filtering is used on the original DSB optical signal to remove either the upper or lower sideband, thus achieving SSB modulation. The main drawback of this method is its stringent filter requirements. When using wavelength division multiplexing (WDM), the cost increases linearly. Furthermore, when using non-tunable filters, system performance is affected by wavelength stability. Methods 2 and 3, one using an IQ modulator and the other using a dual-drive Mach-Zehnder modulator (MZM), share a similar modulation principle, both employing a Hilbert transform-based modulation scheme. The advantage of this scheme is that signal generation is unaffected by the laser, but the disadvantage is that it requires a new transmitter structure, making it incompatible with the existing system. This makes the cost of using it in a large-scale WDM system difficult to estimate, and upgrades are difficult to achieve. In large-scale data center optical interconnects, single-fiber bidirectional transmission technology is typically used to save optical link resources, enabling bidirectional communication within the same fiber. This approach effectively increases the transmission capacity of single-fiber systems, meeting ever-growing capacity demands while maintaining the original system structure. However, backscattering Rayleigh scattering is unavoidable in single-fiber bidirectional systems. This noise reduces the signal-to-noise ratio (SNR) of the received signal, degrading the overall system performance. To avoid backscattering Rayleigh scattering, different wavelengths are typically used for uplink and downlink in single-fiber bidirectional communication. However, this method has drawbacks: it uses more wavelength resources, resulting in higher signal transmission loss and reduced system spectral efficiency. Therefore, effectively reducing the number of high-performance filters and signal transmission loss is a pressing issue that needs to be addressed.

[0053] This application effectively improves the spectrum utilization by generating a double-sideband optical modulation signal based on optical and electrical signals. Then, the double-sideband optical modulation signal is filtered and combined to effectively reduce optical power loss. The generated wavelength division multiplexed single-sideband signal is then transmitted to the receiver for filtering and demultiplexing via the uplink or downlink transmission direction to achieve bidirectional signal transmission and electrical signal restoration. This overcomes the technical defects of high demand for high-performance filters and high signal transmission loss, and can effectively reduce the number of high-performance filters and signal transmission loss.

[0054] Based on this, embodiments of this application provide a signal transmission method applied to a transmitter, as shown below. Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the signal transmission method applied to a transmitter according to this application.

[0055] In this embodiment, the signal transmission method includes steps S10 to S30:

[0056] Step S10: Generate a double-sideband optical modulation signal based on the optical signal and the electrical signal.

[0057] It should be noted that the execution entity in this embodiment is a transmitter, which is a device used to generate and transmit wavelength division multiplexed single-sideband signals. The transmitter includes, but is not limited to, key components such as intensity modulators and wavelength selection switches. The transmitter in this embodiment is the transmitting end in a traditional optical interconnect transceiver architecture.

[0058] It is understood that a double-sideband optical modulated signal is an optical signal containing an upper sideband and a lower sideband. Its spectral characteristics are similar to those of a traditional double-sideband (DSB) signal, but it has a higher spectral efficiency. In the process of generating a double-sideband optical modulated signal, the transmitter combines the electrical signal with the optical signal through specific modulation techniques, such as intensity modulation or phase modulation, thereby achieving efficient use of the spectrum. This embodiment does not impose specific limitations on this.

[0059] In a practical implementation, the transmitter receives an electrical signal from the outside and then combines it with an optical signal to generate a double-sideband optical modulation signal. This process involves converting the electrical signal into an optical signal and combining the two through modulation techniques to form a double-sideband optical modulation signal with specific spectral characteristics.

[0060] In one feasible implementation, step S10 may include: receiving an electrical signal and an optical signal; and modulating the electrical signal and the optical signal to generate a double-sideband optical modulation signal.

[0061] It should be noted that in this embodiment, the transmitter receives multiple electrical signals and optical signals with the same data. For example, it receives N electrical signals and N corresponding optical signals. This embodiment does not impose any specific limitations on this.

[0062] Understandably, electrical signals contain different data information, while optical signals act as carriers to transmit this data information. During modulation, the transmitter modulates these electrical signals with the optical signals respectively, generating multiple double-sideband optical modulation signals, each corresponding to a specific set of data information. Electrical and optical signals can be generated by electrical signal generators and optical signal generators, respectively.

[0063] It is worth noting that the transmitter may also include one or more signal processing units for preprocessing the input electrical signal, such as filtering, amplification, or shaping, to ensure that the signal quality meets modulation requirements. The transmitter is also equipped with a wavelength selection switch to select a suitable wavelength to adapt to different transmission needs.

[0064] In one feasible implementation, the step of modulating the electrical signal and the optical signal to generate a double-sideband optical modulation signal includes: inputting the electrical signal and the optical signal to an intensity modulator, so that the intensity modulator loads the electrical signal onto the optical signal to generate a double-sideband optical modulation signal.

[0065] It should be noted that the transmitter includes multiple intensity modulators for processing the modulation of multiple electrical and optical signals. Each intensity modulator can operate independently to ensure accurate modulation and transmission of the signals. The transmitter may also include one or more wavelength selection switches to dynamically adjust the wavelength of the optical signal to adapt to different network environments and transmission requirements.

[0066] It is understandable that intensity modulator is a key optical modulation technology that encodes data information by changing the intensity of optical signals. In this embodiment, intensity modulator can employ various technologies, such as electroabsorption modulator (EAM) or Mach-Zehnder interferometer (MZI) modulator, to achieve efficient optical signal modulation.

[0067] Understandably, during the modulation process, each intensity modulator loads the corresponding electrical signal onto the corresponding optical signal. That is, the amplitude change of the electrical signal is converted into the intensity change of the optical signal, thereby generating a double-sideband optical modulation signal with specific spectral characteristics. Due to the use of double-sideband optical modulation technology, higher data transmission rate and spectral efficiency can be achieved under the same transmission bandwidth.

[0068] In the specific implementation, an optical signal with wavelength λ1 is used to load an electrical signal 1 (x1(t), with a bandwidth of B) onto an optical carrier via an intensity modulator. According to the intensity modulation formula, the output double-sideband optical modulation signal is y1(t) = (A + x1(t))cos(f1t + ... ), where A is the optical carrier amplitude, and f1 is the frequency corresponding to the optical signal with wavelength λ1. Assuming the initial phase, according to the Fourier transform formula, its signal spectrum is a double-sideband signal centered at λ1 with bandwidth B above and below it. Performing the above operation on all wavelengths generates a set of center wavelengths λ1, λ2, ..., λ... N The double-sideband optical modulation signal.

[0069] Step S20: Filter and combine the double-sideband optical modulation signal to generate a wavelength division multiplexed single-sideband signal.

[0070] It should be noted that the transmitter also includes a wavelength selective switch (WSS) for filtering and multiplexing. The wavelength selective switch can select different wavelength channels as needed, thereby achieving precise control of the signal. In this embodiment, the wavelength selective switch filters each double-sideband optical modulation signal, removes unwanted frequency components, and then multiplexes them into a wavelength division multiplexed single-sideband signal.

[0071] It is understandable that the center wavelengths are λ1, λ2, ..., λ... N The double-sideband optical modulation signal is input to the wavelength selection switch for filtering and multiplexing. During the filtering process, the wavelength selection switch selects an appropriate filter based on the center wavelength of each double-sideband optical modulation signal to remove side lobes and noise, ensuring the quality of the output signal. The filtered signal is then multiplexed, which combines multiple single-sideband optical modulation signals of different wavelengths into one signal for transmission, thus obtaining a wavelength division multiplexed single-sideband signal.

[0072] It's worth noting that Wavelength Division Multiplexing Single Sideband Signaling (WDM-SSB) is a highly efficient signal transmission method used to improve the transmission efficiency and spectral utilization of optical fiber communication systems. WDM-SSB combines the advantages of Wavelength Division Multiplexing (WDM) and Single Sideband Modulation (SSB) technologies, enabling efficient data transmission in optical fiber communication systems. WDM technology allows the simultaneous transmission of multiple signals of different wavelengths in the same optical fiber, significantly increasing the fiber's transmission capacity. Single Sideband Modulation (SSB) is a modulation technique that transmits only one sideband of the information signal (the upper or lower sideband) without transmitting the other sideband and the carrier signal. This saves half the spectral resources and improves transmission efficiency.

[0073] Step S30: The wavelength division multiplexing single sideband signal is transmitted to the receiver via the uplink or downlink transmission direction, so that the receiver filters and demultiplexes the wavelength division multiplexing single sideband signal to generate the restored electrical signal.

[0074] It should be noted that in this embodiment, the transmission of the wavelength division multiplexed single-sideband signal to the receiver employs a bidirectional transmission method. That is, the wavelength division multiplexed single-sideband signal is either an upper sideband signal or a lower sideband signal, which can be transmitted via the uplink and downlink respectively, i.e., transmitted to the receiver via the uplink or downlink transmission direction. In this single-fiber bidirectional transmission system architecture, the uplink and downlink use upper and lower sideband transmission respectively. While maintaining the original system's spectral efficiency, this effectively reduces the impact of backscattering on the system's performance, improving the system's practicality and reliability.

[0075] It is worth noting that the receiver is used to receive wavelength division multiplexed single-sideband signals and perform filtering and demultiplexing to restore the signal, obtaining the restored electrical signal. The restored electrical signal is then demodulated to extract the original information. The receiver's filtering and demultiplexing are also achieved through a wavelength selective switch (WSS).

[0076] It is worth noting that in this application, single-sideband (SSB) filtering is performed on traditional multi-wavelength double-sideband (DSB) signals using a multi-port wavelength selection switch (WSS). That is, multi-wavelength DSB signals are input to different ports corresponding to the WSS, and then the WSS performs unified SSB filtering on the signals of different wavelengths before combining them into a single output, thus generating a WDM-SSB combined signal. Compared to the traditional single-wavelength filtering scheme, this reduces changes to the transmitter structure and the need for a larger number of high-performance filters. Furthermore, the multi-port WSS synthesis method unifies filtering and combining, reducing system optical loss and complexity, and improving system scalability. Finally, the use of an adjustable WSS allows for adjustment of the filtering range based on the frequency offset of different wavelengths, enhancing the flexibility and practicality of the scheme.

[0077] like Figure 2 As shown, Figure 2 This is a block diagram of a transmitter, which includes several intensity modulators and a wavelength selection switch, with wavelengths of λ1, λ2, ..., λ... N The optical signal is modulated by an intensity modulator to load electrical signals 1, 2, ..., N onto the optical carrier, generating a set of center wavelengths λ1, λ2, ..., λN. N Furthermore, each double-sideband optical modulation signal with a bandwidth of B is input to a different port corresponding to a wavelength selection switch. The wavelength selection switch performs filtering and multiplexing, and finally outputs a wavelength division multiplexed single-sideband signal.

[0078] In a feasible implementation, step S30, "transmitting the wavelength division multiplexing single sideband signal to the receiver via the uplink transmission direction or the downlink transmission direction," specifically includes: when the wavelength division multiplexing single sideband signal is an upper sideband signal, transmitting the upper sideband signal to the receiver via the uplink transmission direction; and when the wavelength division multiplexing single sideband signal is a lower sideband signal, transmitting the lower sideband signal to the receiver via the downlink transmission direction.

[0079] It should be noted that when bidirectional transmission is used, the wavelength selection switch WSS generates upper sideband and lower sideband signals respectively according to the different transmission directions. Since the bidirectional transmission signals do not overlap in frequency, back Rayleigh scattering is almost unaffected, thereby improving system performance. When bidirectional transmission is used, the center wavelength of the signals is the same, so the wavelength efficiency is not reduced, maintaining the original practicality and reliability of bidirectional transmission.

[0080] It is understandable that the upper sideband signal is the upper sideband portion containing information, while the lower sideband signal is the lower sideband portion containing information. By selectively transmitting the upper or lower sideband signal according to the channel direction, interference between signals can be effectively reduced and transmission quality improved.

[0081] It is worth noting that when using single-fiber bidirectional N-wavelength wavelength division multiplexing (WDM), its spectral structure is as follows: the lower sideband signal, i.e., the downlink signal, has center wavelengths of f1+B / 2, f2+B / 2, ..., f... N +B / 2, a signal with bandwidth B; the upper sideband signal, i.e., the uplink signal, has center wavelengths of f1-B / 2, f2-B / 2, ..., f... N -B / 2, a signal with a bandwidth of B. The uplink and downlink modulated signals do not overlap in the spectrum, with only a partial overlap in the carrier portion. Therefore, during bidirectional transmission, even if there is some backscattered optical signal, since the main component of the scattering is the carrier portion, it is mainly converted into DC during photoelectric detection. Thus, the impact on the original receiving system is minimal. At the same time, by adopting a bidirectional transmission method, the system capacity is increased several times without changing the original system structure. This method is almost unaffected by backscattering, effectively improving the overall system capacity.

[0082] like Figure 3 As shown, Figure 3 This is a schematic diagram of wavelength division multiplexing (WDM) single-sideband (SSB) signal transmission. The spectral structure of the WDM SSB signal is as follows: the downlink signals are respectively center wavelengths f1+B / 2, f2+B / 2, ..., f N A signal with a bandwidth of B and a value of +B / 2; the uplink signals are respectively center wavelengths of f1-B / 2, f2-B / 2, ..., f NA signal with a bandwidth of -B / 2 and a bandwidth of B is transmitted in the uplink and downlink directions, respectively.

[0083] This embodiment provides a signal transmission method applied to a transmitter. The method involves first generating a double-sideband optical modulation signal based on optical and electrical signals; then filtering and multiplexing the double-sideband optical modulation signal to generate a wavelength division multiplexing (WDM) single-sideband signal; finally, transmitting the WDM single-sideband signal to a receiver via an uplink or downlink transmission direction. The receiver then filters and demultiplexes the WDM single-sideband signal to generate a restored electrical signal, effectively reducing the number of high-performance filters and signal transmission loss.

[0084] In summary, this embodiment effectively improves the spectrum utilization by generating a double-sideband optical modulation signal based on optical and electrical signals. This allows for filtering and multiplexing of the double-sideband optical modulation signal, effectively reducing optical power loss. The generated wavelength division multiplexed single-sideband signal is then transmitted to the receiver via either the uplink or downlink direction for filtering and demultiplexing, achieving bidirectional signal transmission and electrical signal restoration. This overcomes the technical shortcomings of high-performance filter requirements and high signal transmission loss, effectively reducing the number of high-performance filters and signal transmission loss.

[0085] Based on the first embodiment of the signal transmission method for a transmitter of this application, in the second embodiment of the signal transmission method for a transmitter of this application, the content that is the same as or similar to that in the first embodiment described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 4 Step S20 further includes steps S201-S202:

[0086] Step S201: Filter the double-sideband optical modulation signal to generate a single-sideband optical modulation signal.

[0087] It should be noted that filtering is achieved through a wavelength selective switch (WSS), which selects the center wavelengths as λ1, λ2, ..., λ... N Furthermore, the double-sideband optical modulation signals, each with a bandwidth of B, are input to different ports corresponding to the wavelength selection switch (WSS). The number of input ports of the wavelength selection switch can be greater than N, thereby flexibly increasing the number of WDM wavelengths and improving the scalability of the system.

[0088] It is understandable that the filtering parameters for the wavelength selective switch WSS are set such that the filtering parameters for ports 1, 2, ..., N are respectively set to center frequencies f1+B / 2, f2+B / 2, ..., f NA low-pass filter with a bandwidth of +B / 2 and a bandwidth of B is used for filtering to generate a single-sideband optical modulation signal, i.e., the lower sideband signal. When a high-pass filter is used for filtering, the generated single-sideband optical modulation signal is the upper sideband signal. This embodiment does not impose specific limitations on this; this embodiment uses the generation of the lower sideband signal by a low-pass filter as an example for explanation.

[0089] It is worth noting that by filtering the double-sideband optical modulation signal to generate a single-sideband optical modulation signal, the bandwidth requirement of the optical signal can be effectively reduced, thereby reducing the occupation of bandwidth resources during transmission. By precisely controlling the filtering parameters, the signal quality can be further optimized, ensuring the stability and reliability of the signal during transmission.

[0090] It is worth noting that double-sideband optical modulation signals include the upper and lower sidebands of the information signal, but do not include the carrier signal. Single-sideband optical modulation signals only include one sideband of the information signal. Usually, the upper sideband (USB) or the lower sideband (LSB) is selected. By filtering out the unwanted sidebands in the double-sideband optical modulation signal, the single-sideband optical modulation signal can be obtained.

[0091] Step S202: The single-sideband optical modulation signal is combined to generate a wavelength division multiplexed single-sideband signal.

[0092] It should be noted that the multiplexing is also achieved through a wavelength selective switch (WSS), that is, all filtered signals are combined with equal gain to form a wavelength division multiplexed single sideband signal (WDM-SSB) that can be input into an optical fiber for transmission.

[0093] In one feasible implementation, step S202 may include: performing equal-gain amplification on the single-sideband optical modulation signal to obtain an amplified single-sideband optical modulation signal; and performing signal merging on the amplified single-sideband optical modulation signal to generate a wavelength division multiplexed single-sideband signal.

[0094] It should be noted that equal gain amplification means that the gain of each signal remains consistent during the amplification process to ensure that different signals have the same power level when combined. This avoids some signals being over-amplified during the combination process, resulting in nonlinear distortion, while also ensuring the detectability of weaker signals.

[0095] Understandably, after equal gain amplification, the individual single-sideband optical modulation signals are precisely combined through precise timing control and wavelength selection switch (WSS) configuration to form a wavelength division multiplexed single-sideband signal (WDM-SSB) containing all information. The WDM-SSB signal can include either an upper sideband signal or a lower sideband signal, as shown in the following equation:

[0096] y1(t) = Acos(f1t + )+ x1(t) cos(f1t+ )+ x1(t) sin(f1t+ )

[0097] y1'(t) = Acos(f1t + )+ x1(t) cos(f1t+ )- x1'(t) sin(f1t+ )

[0098] Where y1(t) is the lower sideband signal, y1'(t) is the upper sideband signal, A is the optical carrier amplitude, and f1 is the frequency corresponding to the optical signal with wavelength λ1. Let x1(t) be the initial phase, x1(t) be the electrical signal, and x1'(t) be the Hilbert transformation of the electrical signal.

[0099] It's worth noting that the advantage of using a wavelength selective switch (WSS) for filtering and multiplexing lies in its simplified system structure compared to filtering each wavelength individually. Furthermore, the WSS allows all SSB signals to be multiplexed uniformly after filtering, effectively reducing system optical power loss and improving post-multiplexing performance compared to traditional filtering followed by multiplexing. Typically, in data center optical interconnect environments, due to cost considerations, a fixed grid structure can be used for the WSS to achieve low cost. In less cost-sensitive scenarios, an adjustable WSS solution can be chosen. This allows for adaptive adjustment of the filter's center wavelength to reposition even when laser performance deviates, causing frequency shifts, without affecting the overall WDM-SSB transmission system.

[0100] In this embodiment, the double-sideband optical modulation signal is filtered and combined by a wavelength selection switch, and the filtering and combining are unified, which effectively reduces optical power loss.

[0101] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the signal transmission method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0102] This application also provides a signal transmission method applied to a receiver, as described in the embodiments below. Figure 5 , Figure 5 This is a flowchart illustrating the first embodiment of the signal transmission method applied to a receiver according to this application.

[0103] In this embodiment, the signal transmission method includes steps S10'~S20':

[0104] Step S10': Receive the wavelength division multiplexed single-sideband signal sent by the transmitter.

[0105] It should be noted that the execution entity in this embodiment is a receiver, which is a device used to receive wavelength division multiplexed single-sideband signals and perform signal reconstruction. The transmitter includes, but is not limited to, key components such as wavelength selection switches and photodetectors. The receiver in this embodiment is the receiving end in a traditional optical interconnect transceiver architecture.

[0106] Understandably, the wavelength division multiplexed single-sideband signal transmitted by the transmitter is fed into the wavelength selection switch of the receiver for filtering and wavelength division processing after bidirectional transmission.

[0107] It is worth noting that the wavelength division multiplexing single-sideband signal transmitted by the transmitter is obtained by combining multiple single-sideband signals. It can include either the upper sideband signal or the lower sideband signal at the same time. Therefore, filtering and demultiplexing are required to ensure that each signal can be correctly restored.

[0108] Step S20': Filter and demultiplex the wavelength division multiplexed single-sideband signal to generate the restored electrical signal.

[0109] It should be noted that the filtering and demultiplexing of the wavelength division multiplexing (WDM) single-sideband (SSB) signal are achieved through a wavelength selection switch in the receiver. In this application, both the double-sideband optical modulation signal and the WDM SSB signal undergo SSB filtering via a wavelength selection switch. The wavelength selection switch can be constructed from structures such as liquid crystal on silicon (LCOS), microelectromechanical systems (MEMS), and planar lightwave circuits (PLCs).

[0110] As can be understood, filtering refers to separating a specific wavelength of optical signal from a mixed signal, that is, filtering out the unwanted sidebands in a wavelength division multiplexing (WDM) single-sideband signal. This can be either the upper or lower sideband; this embodiment does not impose specific limitations. This embodiment uses filtering the upper sideband as an example for explanation. In this case, the receiver is a downlink receiver. Wavelength division further distributes the separated signal into different paths. The receiver's wavelength selection switch performs filtering and wavelength division operations to ensure that each single-sideband signal can be accurately restored to an electrical signal.

[0111] In this embodiment, the wavelength selection switch is used to filter and demultiplex the wavelength division multiplexed single-sideband signal, which can accurately restore the electrical signal and effectively reduce signal transmission loss.

[0112] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the signal transmission method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0113] Based on the first embodiment of the signal transmission method for a receiver applied to this application, in the second embodiment of the signal transmission method for a receiver applied to this application, the content that is the same as or similar to the above-described embodiment two can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 6 Step S20' further includes steps S201'-S202':

[0114] Step S201': Filter and demultiplex the wavelength division multiplexed single-sideband signal to generate the target single-sideband signal.

[0115] It should be noted that wavelength division multiplexing (WDM) single-sideband signals are hybrid signals that combine upper or lower sideband signals. By using the filtering function of a wavelength selection switch, optical signals of a specific wavelength can be separated, i.e., unwanted sidebands, such as upper or lower sidebands, can be filtered out.

[0116] Understandably, when the receiver is a downlink receiver, the target single-sideband signal is the lower sideband signal after signal separation. The wavelength selection switch's demultiplexing function further separates the filtered signal and routes it to different paths, ensuring that each single-sideband signal can be accurately reconstructed into an electrical signal.

[0117] In one feasible implementation, step S201' may include: filtering the wavelength division multiplexing single-sideband signal to obtain a filtered single-sideband signal; and performing signal separation on the filtered single-sideband signal to generate a target single-sideband signal.

[0118] It should be noted that when the receiver is a downlink receiver, the receiver's wavelength selection switch is configured as a 1-input N-output multiport filter structure. Ports 1 to N correspond to the same filtering parameters of the transmitter's wavelength selection switch, i.e., the center frequencies are f1+B / 2, f2+B / 2, ..., f... N A low-pass filter with a bandwidth of +B / 2 and a bandwidth of B can be used to output single-sideband signals of different wavelengths from port 1 to N, i.e., filtered single-sideband signals.

[0119] It is understandable that separating the filtered single-sideband signal into multiple signals and performing signal reconstruction separately can further improve the accuracy and efficiency of signal reconstruction. Signal separation can also be achieved through filters.

[0120] Step S202': Perform signal restoration on the target single-sideband signal to generate the restored electrical signal.

[0121] It should be noted that in this embodiment, signal reconstruction is accomplished using photodetectors. The receiver includes multiple photodetectors, which convert optical signals into electrical signals. The photodetectors can be PIN diodes or avalanche photodiodes (APDs), which respond to changes in the optical signal and generate corresponding current or voltage signals. In the receiver, the target single-sideband signal is first filtered and divided by a wavelength selective switch, and then converted into an electrical signal by the photodetectors.

[0122] In one feasible implementation, step S202' may include: sending the target single-sideband signal to a photodetector so that the photodetector performs photoelectric conversion on the target single-sideband signal to generate a restored electrical signal.

[0123] It should be noted that the transmitter includes photodetectors for signal reconstruction. Each photodetector can operate independently to improve the efficiency and reliability of signal reconstruction. The output electrical signal from the photodetector can then be further processed, for example, amplified by an amplifier and subjected to necessary signal shaping and noise filtering by subsequent signal processing circuitry to ensure the quality of the final output electrical signal.

[0124] It is understandable that the target single-sideband signal is received by squaring through a photodetector. That is, the SSB optical signal is converted into an electrical signal by the photodetector. In other words, the photodetector converts the received light intensity into a corresponding current output, and the current output by the photodetector is squared. Then, the squared signal is restored to the electrical signal input to the transmitter, that is, the restored electrical signal.

[0125] It is worth noting that when the target single-sideband signal is received squared by the photodetector, the normalized signal output is Z(t) = A. 2 +Ax(t)+x 2 (t)+x1' 2 (t), where the last two terms are the Selfie noise of the signal. When the carrier-to-signal power ratio (CSPR) of the signal is large enough, that is, when the signal carrier energy is large enough, that is, when A is large enough, the noise can be ignored, and the original transmitted signal can be recovered from the SSB signal, that is, the restored electrical signal can be obtained.

[0126] like Figure 7 As shown, Figure 7 This is a block diagram of the receiver. The receiver includes a wavelength selective switch and several photodetectors. The wavelength division multiplexed single-sideband signal is filtered and demultiplexed by the wavelength selective switch to generate a set of center wavelengths λ1, λ2, ..., λ3. N Furthermore, a single-sideband signal with a bandwidth of B is used, and each single-sideband signal is input to the corresponding photodetector for signal reconstruction.

[0127] In this embodiment, by filtering and demultiplexing the wavelength division multiplexed single-sideband signal, and then restoring the signal, the input signal can be accurately restored, effectively reducing signal transmission loss and improving the accuracy of information restoration.

[0128] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the signal transmission method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0129] This application provides a signal transmission system, which includes a transmitter and a receiver. The transmitter and the receiver execute the signal transmission method described above.

[0130] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0131] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0132] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described signal transmission method, thereby solving the technical problem of how to effectively reduce the number of high-performance filters and signal transmission loss. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the signal transmission method provided in the above embodiments, and will not be repeated here.

[0133] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the signal transmission method described above.

[0134] The computer program product provided in this application can solve the technical problem of how to effectively reduce the number of high-performance filters and signal transmission loss. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as the beneficial effects of the signal transmission method provided in the above embodiments, and will not be repeated here.

[0135] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A signal transmission method, characterized in that, The signal transmission method is applied to a transmitter, and the method includes: Double-sideband optical modulation signals are generated based on optical and electrical signals; The double-sideband optical modulation signal is filtered and combined to generate a wavelength division multiplexing single-sideband signal. The spectral structure of the wavelength division multiplexing single-sideband signal includes a downlink signal and an uplink signal, which are transmitted in the uplink transmission direction and the downlink transmission direction, respectively. The wavelength division multiplexing single sideband signal is transmitted to the receiver via the uplink or downlink transmission direction, so that the receiver filters and demultiplexes the wavelength division multiplexing single sideband signal to generate the restored electrical signal. The transmitter includes a wavelength selection switch, which is used for filtering and multiplexing, and selects different wavelength channels as needed. The step of filtering and combining the double-sideband optical modulation signal to generate a wavelength division multiplexed single-sideband signal includes: filtering the double-sideband optical modulation signal to generate a single-sideband optical modulation signal; and combining the single-sideband optical modulation signal to generate a wavelength division multiplexed single-sideband signal.

2. The method as described in claim 1, characterized in that, The generation of a double-sideband optical modulation signal based on optical and electrical signals includes: Receives electrical and optical signals; The electrical signal and the optical signal are input to an intensity modulator, so that the intensity modulator loads the electrical signal onto the optical signal to generate a double-sideband optical modulation signal.

3. The method as described in claim 1, characterized in that, The process of combining the single-sideband optical modulation signal to generate a wavelength division multiplexed single-sideband signal includes: The single-sideband optical modulation signal is amplified by equal gain to obtain an amplified single-sideband optical modulation signal. The amplified single-sideband optical modulation signal is combined to generate a wavelength division multiplexed single-sideband signal.

4. The method as described in claim 1, characterized in that, The step of transmitting the wavelength division multiplexed single-sideband signal to the receiver via the uplink or downlink transmission direction includes: When the wavelength division multiplexing single sideband signal is an upper sideband signal, the upper sideband signal is transmitted to the receiver through the uplink transmission direction; When the wavelength division multiplexing single sideband signal is a lower sideband signal, the lower sideband signal is transmitted to the receiver through the downlink transmission direction.

5. A signal transmission method, characterized in that, The signal transmission method is applied to a receiver, and the method includes: The receiver transmits wavelength division multiplexing single-sideband signals, wherein the spectral structure of the wavelength division multiplexing single-sideband signals includes downlink signals and uplink signals, which are transmitted in the uplink transmission direction and the downlink transmission direction, respectively. The wavelength division multiplexed single-sideband signal is filtered and demultiplexed to generate the restored electrical signal; The transmitter includes a wavelength selection switch, which is used for filtering and multiplexing, and selects different wavelength channels as needed. The step of filtering and demultiplexing the wavelength division multiplexed single-sideband signal to generate a target single-sideband signal includes: filtering the wavelength division multiplexed single-sideband signal to obtain a filtered single-sideband signal; and performing signal separation on the filtered single-sideband signal to generate the target single-sideband signal.

6. The method as described in claim 5, characterized in that, The step of filtering and demultiplexing the wavelength division multiplexed single-sideband signal to generate the restored electrical signal includes: The wavelength division multiplexed single-sideband signal is filtered and demultiplexed to generate the target single-sideband signal; The target single-sideband signal is restored to generate a restored electrical signal.

7. The method as described in claim 6, characterized in that, The step of restoring the target single-sideband signal to generate a restored electrical signal includes: The target single-sideband signal is sent to a photodetector, so that the photodetector performs photoelectric conversion on the target single-sideband signal to generate a restored electrical signal.

8. A signal transmission system, characterized in that, The signal transmission system includes a transmitter and a receiver, wherein the transmitter performs the signal transmission method as described in any one of claims 1 to 4, and the receiver performs the signal transmission method as described in any one of claims 5 to 7.

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