Optical fiber downlink communication and sensing integrated waveform design method and system based on water injection method

Abstract

The application discloses a fiber downlink and sensing integrated waveform design method and system based on a water injection method, and the method is as follows: 1, combining the communication signal power spectrum distribution of an ISAC-OF system with communication as the center, system sensing mutual information is calculated; 2, combining the system sensing signal transmission power limit, the maximum value of the system sensing mutual information is calculated; 3, the system sensing link noise is calculated through the maximum value of the system sensing mutual information, and the sensing signal power spectrum distribution is calculated through the water injection method; 4, the system sensing signal waveform is selected, parameters are set so that the power spectrum distribution is consistent with the sensing signal power spectrum distribution, and the system sensing signal is obtained; 5, the sensing signal and the system communication signal are added, and are modulated into optical signals and coupled into optical fiber transmission; 6, after optical fiber transmission, the communication signal is filtered out at the communication receiving end, is received by an optical communication receiver and communication data is obtained; the sensing signal is filtered out at the sensing receiving end, is received by an optical sensing receiver and sensing data is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical communication, and particularly relates to an integrated waveform design method and system for a communication-centered integrated sensing and communication system on an optical fiber. BACKGROUND

[0002] In recent years, with the rapid development of emerging network service technologies such as cloud computing, Internet of Things, virtual reality, and the like, the demand of network users for high speed, large bandwidth, and low latency is also gradually increasing. According to research, by 2025, it is predicted that the total number of global Internet users will reach 5.7 billion, accounting for about 70% of the total global population. As the main infrastructure for data transmission today, the scale of fiber optic networks is also rapidly growing. Intelligent management and health detection of such large infrastructures have gradually become new challenges. In addition, with the emergence of emerging technologies such as smart cities and remote medical care, the stable combination of high-quality communication and high-precision sensing has become a new demand. At the same time, as the potential of the sensing function of optical fibers is explored, the Integrated Sensing and Communication on Optical Fiber (ISAC-OF) technology has emerged. ISAC-OF technology is an organic combination of communication and sensing functions under the same optical fiber link by applying various technical means, thereby more effectively utilizing limited system resources. Among them, the technical means applied include but are not limited to resource multiplexing technology, integrated hardware integration technology, and integrated waveform design technology, etc. Through the above technologies, the existing optical fiber network will have the sensing ability of the environment around itself on the basis of maintaining the original communication ability, thereby making the network management more intelligent and the network business more diversified. However, ISAC-OF technology still faces many challenges, such as communication-sensing signal crosstalk and system resource allocation trade-off, etc. From the perspective of information and business targets, the above problems are essentially caused by the differences in the acquisition and processing methods of communication and sensing information. Therefore, how to solve the internal conflict between communication and sensing in the signal and system design of the ISAC system is an important research problem. At the same time, the trade-off between the communication and sensing performance of the system is also a key research issue.

[0003] Through retrieval of existing literature, it is found that for the above problems, in wireless ISAC, the main research direction is to analyze the performance limit of ISAC system, design integrated waveform and system architecture. Among them, Xiong Yifeng et al. published in 2023 in China Science Communication Sensing Integrated Information Theory Limit Based on wireless channel analysis of ISAC system performance limit in four different scenarios, and pointed out that the performance compromise of wireless ISAC system can be further divided into deterministic-random compromise and subspace compromise. In addition, Rang Liu et al. published in 2021 in IEEE Transactions on Signal Processing Cramer-Rao Bound Optimization for Joint Radar-Communication Beamforming Proposed using Cramer-Rao bound (CRB) as the performance index of target estimation, minimizing the CRB of radar sensing under the premise of ensuring the preset signal-to-noise ratio level of each communication user, thereby realizing the multiple-input multiple-output beamforming design for joint radar sensing and multi-user communication. However, due to the different optimization targets and application scenarios of different system links, the above wireless ISAC technical solutions are difficult to be directly applied to ISAC-OF system. Therefore, Haijun He1 et al. published in 2023 in Light: Science & Applications Integrated sensing and communication in an optical fibre, which proposed using linear frequency modulation signal as carrier wave, can realize high-speed optical communication and optical fiber vibration monitoring at the same wavelength channel, realizing the organic integration of high-speed communication and high-precision sensing in optical fiber. However, the above scheme still lacks in-depth discussion on the performance of ISAC-OF system, and lacks theoretical analysis on the influence of system signal crosstalk. Therefore, the present application provides an integrated waveform design method and system based on water injection method for communication-centered integrated sensing and communication system in optical fiber. SUMMARY

[0004] In view of the lack of theoretical analysis of signal crosstalk and system performance of the current communication-centered integrated sensing and communication system in optical fiber, the present application provides an integrated waveform design method and system based on water injection method. Water injection method is a system optimization method that injects signal power at the noise level to achieve optimal system performance. The present application establishes a mathematical model, analyzes the crosstalk and system performance, and optimizes the parameters. After optimization, only the parameter sensing channel noise needs to be calculated according to the result, and the sensing signal spectrum distribution can be obtained based on the water injection method, thereby generating the optimal integrated waveform of the system and realizing the high-performance integrated sensing and communication system in optical fiber.

[0005] The application adopts the following technical solutions:

[0006] A fiber downlink communication and sensing integrated waveform design method based on water-filling method, the specific steps are as follows:

[0007] Step 1, combining the communication signal power spectrum distribution of the communication and sensing integrated system, the fiber channel dispersion, the channel noise power spectrum distribution and the sensing target unit impulse response, the system sensing mutual information is calculated;

[0008] Step 2, combining the system sensing signal transmission power limit, the maximum value of the system sensing mutual information in step 1 is calculated;

[0009] Step 3, the maximum value of the system sensing mutual information obtained in step 2 is used to calculate the system sensing link noise and the water level, and the sensing signal power spectrum distribution is calculated by water-filling method;

[0010] Step 4, the system sensing signal waveform is selected, and its parameters are set to make its power spectrum distribution consistent with the sensing signal power spectrum distribution obtained in step 3, and the system sensing signal is obtained;

[0011] Step 5, the sensing signal obtained in step 4 is added to the system communication signal to generate a corresponding electrical signal, which is modulated into an optical signal and transmitted through an optical fiber;

[0012] Step 6, after the optical signal is transmitted through the optical fiber and affected by the sensing target, the communication signal is filtered out at the communication receiving end, and the communication information is obtained by the optical communication receiver; at the sensing receiving end, the sensing signal is filtered out, and the sensing target information is obtained by the optical sensing receiver.

[0013] Further, in the frequency spectrum range W=[f0, f0+W] with the lowest frequency f0 of the system transmission signal as the starting point, combining the communication signal power spectrum distribution of the communication and sensing integrated system The fiber channel dispersion CD(f), the channel noise power spectrum distribution P nn (f) and the sensing target unit impulse response g(t), the system sensing mutual information is calculated, and the expression is as follows:

[0014]

[0015] Wherein, y sc (t) is the system sensing integrated waveform signal, x s (t) is the sensing signal to be designed, and the power spectrum distribution is X s (f); is the signal transmission duration; The variance of the power spectrum distribution G(f) of g(t).

[0016] Further, in step 2, the sensing signal power limit is determined by the system transmitting end device parameters.

[0017] Further, in step 2, the sensing signal power limit is combined with the system sensing signal transmission power limit Under this power limit, the maximum value of the system sensing mutual information in step 1 is calculated:

[0018]

[0019] Where E x is the sensing signal energy limit.

[0020] Further, step 3 is as follows: the maximum value of the system sensing mutual information obtained in step 2 is used to calculate the system sensing link noise r(f) and the injection level A:

[0021]

[0022] And the sensing signal power spectrum distribution is calculated by the water injection method:

[0023] |X s (f)| 2 = max [0, A-r(f)] (5)

[0024] In step 2, the maximum value of the system sensing mutual information is calculated by using the Lagrange multiplier method to construct a constraint function; the constraint function is as follows:

[0025]

[0026] Further, in step 4, the selection of the sensing signal waveform is determined by the specific system and application scenario, and common waveforms are pulse signals or linear frequency modulation signals, etc.

[0027] Further, step 5 is as follows: the sensing signal obtained in step 4 is added to the system communication signal, and the corresponding electrical signal is generated by an arbitrary signal generator, modulated into an optical signal by an optical modulator, and coupled into an optical fiber for transmission.

[0028] Further, step 6 is as follows: after the optical signal is transmitted through the optical fiber and affected by the sensing target, at the communication receiving end, the communication signal is filtered out by an optical filter, received by an optical communication receiver, and the communication information is obtained; at the sensing receiving end, the sensing signal is filtered out by an optical filter, received by an optical sensing receiver, and the sensing target information is obtained.

[0029] The application also discloses an optical fiber downlink communication and sensing integrated waveform design system based on the water-filling method.

[0030] The transmission module: combines the communication signal power spectrum distribution of the communication-centered optical fiber downlink communication and sensing integrated system, the optical fiber channel dispersion, the channel noise power spectrum distribution and the sensing target unit impulse response to calculate the system sensing mutual information; combines the system sensing signal transmission power limit to calculate the maximum value of the system sensing mutual information; calculates the system sensing link noise and the water level through the maximum value of the obtained system sensing mutual information, and calculates the sensing signal power spectrum distribution through the water-filling method; selects the system sensing signal waveform, and sets the parameters to make the power spectrum distribution consistent with the obtained sensing signal power spectrum distribution to obtain the system sensing signal; adds the obtained sensing signal and the system communication signal to generate a corresponding electrical signal, modulates the electrical signal into an optical signal, and transmits the optical signal to the receiving module through the optical fiber;

[0031] The receiving module: after the optical signal is transmitted through the optical fiber and affected by the sensing target, filters out the communication signal at the communication receiving end, receives the communication signal by the optical communication receiver and obtains the communication information; filters out the sensing signal at the sensing receiving end, receives the sensing signal by the optical sensing receiver and obtains the sensing target information.

[0032] Compared with the prior art, the application has the following beneficial effects:

[0033] 1. Simple and fast waveform design: under the condition of known system parameters, the sensing signal power spectrum distribution can be obtained through simple calculation by calculating the sensing link noise and combining the water-filling method. The actual sensing only needs to make the power spectrum density consistent with the calculation result to obtain superior system sensing performance.

[0034] 2. Good generalization ability: compared with the existing integrated waveform design method combined with the system architecture, the sensing link noise can be used for the design of the integrated waveform without recalculation under the condition that the system parameters and the communication signal do not change. Therefore, the application can be deployed in a wide range of ISAC-OF systems and has good generalization ability.

[0035] 3. Comprehensive analysis of system performance: the application analyzes the main influencing factors such as optical fiber dispersion and thermal noise suffered by the short-distance ISAC-OF system, and has a comprehensive analysis of the system performance. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is a preferred embodiment of the application, a communication and sensing integrated waveform design system based on the water-filling method;

[0037] Figure 2is a flow chart of a communication and sensing integrated waveform design method based on water-filling method according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to more clearly illustrate the embodiments of the present application, the specific embodiments of the present application will be described below with reference to the accompanying drawings. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without creative labor, and other embodiments can also be obtained.

[0039] As shown in Figures 1-2 , the present embodiment proposes a communication and sensing integrated waveform design method based on water-filling method for optical fiber downlink, and the specific steps are as follows:

[0040] Step 1: In the frequency spectrum range W = [f0, f0+W], the communication signal power spectrum distribution of the communication and sensing integrated system for optical fiber downlink is combined with the communication as the center , the channel noise power spectrum distribution P nn (f) and the sensing target unit impulse response g(t), the system sensing mutual information expression is calculated:

[0041]

[0042] Where y sc (t) is the system sensing integrated waveform signal, x s (t) is the sensing signal to be designed, and the power spectrum distribution is X s (f); is the signal transmission time length; is the variance of the power spectrum distribution G(f) of g(t);

[0043] Step 2: The system sensing signal transmission power limit is combined Under this power limit, the maximum value of the system sensing mutual information in step 1 is calculated:

[0044]

[0045] Where E x is the sensing signal energy limit.

[0046] By using the Lagrange multiplier method, a constraint function is constructed:

[0047]

[0048] The maximum value of the system sensing mutual information calculated.

[0049] In step 2, the sensing signal power limit is determined by the system transmitting end device parameters.

[0050] Step 3: Calculate the system sensing link noise r(f) and the injection level A by the maximum value of the system sensing mutual information obtained in step 2:

[0051]

[0052] And calculate the sensing signal power spectrum distribution by the injection method:

[0053] |X s (f)| 2 = max [0, A-r(f)] (12)

[0054] Step 4: Select the system sensing signal waveform, and set its parameters to make its power spectrum distribution as consistent as possible with the sensing signal power spectrum distribution obtained in step 3, so as to obtain the system sensing signal. The selection of the sensing signal waveform is determined by the specific system and application scenario, and the commonly used waveforms are pulse signals or linear frequency modulation signals.

[0055] Step 5: Add the sensing signal obtained in step 4 to the system communication signal, generate the corresponding electrical signal by any signal generator, modulate it into an optical signal by an optical modulator, and couple it into an optical fiber for transmission.

[0056] Step 6: After the optical signal is transmitted through the optical fiber and affected by the sensing target, at the communication receiving end, the communication signal is filtered out by the optical filter, received by the optical communication receiver, and the communication information is obtained; at the sensing receiving end, the sensing signal is filtered out by the optical filter, received by the optical sensing receiver, and the sensing target information is obtained.

[0057] The present application firstly establishes a mathematical model for a communication-centered optical fiber downlink sensing integrated system, calculates the sensing link noise by combining the system parameters and the communication signal model, designs the sensing signal power spectrum distribution using the injection method based on the noise, and finally designs an integrated waveform, optimizes the system performance, and realizes simple and fast downlink sensing integrated waveform design, thereby constructing a high-performance optical fiber downlink sensing integrated system.

[0058] As Figure 1As shown, the embodiment discloses a fiber downlink communication and sensing integrated waveform design system based on the water-filling method, which is used to execute the above method, and the system comprises a transmission module and a receiving module, the transmission module comprises an arbitrary signal generator and an optical modulator, a waveform signal designed by the water-filling method is generated into a corresponding electrical signal by the arbitrary signal generator, and then the electrical signal is converted into an optical signal by the optical modulator and coupled into an optical fiber to be transmitted to the receiving module. The receiving module is composed of an optical filter module, an optical communication receiver module, an optical sensing receiver module and the like, wherein two optical filter modules are used to filter out communication receiving signals and sensing receiving signals respectively, and the two signals enter corresponding optical receivers to be demodulated to obtain corresponding communication and sensing information. The specific structures of the optical communication receiver module and the optical sensing receiver module are determined according to the communication mode and the sensing mode adopted. Specifically:

[0059] The transmission module: combining the communication signal power spectrum distribution of the communication-centered fiber downlink communication and sensing integrated system, the fiber channel dispersion, the channel noise power spectrum distribution and the sensing target unit impulse response, the system sensing mutual information is calculated; combining the system sensing signal transmission power limit, the maximum value of the system sensing mutual information is calculated; the system sensing link noise and the water level are calculated through the maximum value of the system sensing mutual information, and the sensing signal power spectrum distribution is calculated by the water-filling method; the system sensing signal waveform is selected, and its parameters are set to make its power spectrum distribution consistent with the obtained sensing signal power spectrum distribution, so as to obtain the system sensing signal; the obtained sensing signal and the system communication signal are added to generate a corresponding electrical signal, which is modulated into an optical signal and transmitted to the receiving module through the optical fiber;

[0060] The receiving module: after the optical signal is transmitted through the optical fiber and affected by the sensing target, the communication signal is filtered out at the communication receiving end, received by the optical communication receiver and the communication information is obtained; at the sensing receiving end, the sensing signal is filtered out, received by the optical sensing receiver and the sensing target information is obtained.

[0061] Other contents of the embodiment can refer to the above method embodiment.

[0062] In summary, by analyzing the performance of the ISAC-OF system, the optimal integrated waveform is designed, which can effectively reduce the influence of system signal crosstalk and improve the communication and sensing performance of the system.

[0063] It should be noted that the above only details the preferred embodiments and principles of the present application, and for ordinary skilled persons in the art, the specific implementation manner can be changed according to the idea provided by the present application, and these changes should be regarded as the protection scope of the present application.

Claims

1. A waveform design method for integrated communication and sensing under optical fiber based on water injection method, characterized by: The steps are as follows: Step 1, the communication signal power spectrum distribution of the communication and perception integrated system under the optical fiber communication, the optical fiber channel dispersion, the channel noise power spectrum distribution and the unit impulse response of the perception target are combined to calculate the system perception mutual information; Step 2, the maximum value of the system perception mutual information in step 1 is calculated in combination with the system perception signal transmission power limit; Step 3, the maximum value of the system perception mutual information obtained in step 2 is used to calculate the system perception link noise and the injection level, and the injection water method is used to calculate the perception signal power spectrum distribution; Step 4, the system perception signal waveform is selected, and the parameters are set to make the power spectrum distribution consistent with the perception signal power spectrum distribution obtained in step 3, to obtain the system perception signal; Step 5, the perception signal obtained in step 4 is added to the system communication signal to generate a corresponding electrical signal, which is modulated into an optical signal and transmitted through an optical fiber; Step 6, after the optical signal is transmitted through the optical fiber and affected by the perception target, the communication signal is filtered out at the communication receiving end, received by the optical communication receiver and the communication information is obtained; at the perception receiving end, the perception signal is filtered out, received by the optical perception receiver and the perception target information is obtained; Step 1 is specifically as follows: in the frequency spectrum range W = [f0, f0 + W] starting from the lowest frequency f0 of the system transmission signal, the communication signal power spectrum distribution P xc (f) and the channel noise power spectrum distribution P nn (f) and the sensing target unit impulse response g(t), the system sensing mutual information is calculated, and the expression is as follows: where y sc (t) is the system integrated waveform signal, x s (t) is the perception signal to be designed, whose power spectral distribution is X s (f); is the signal transmission duration; is the variance of the power spectral distribution G(f) of g(t). Step 2 is specified as follows: Combine system sensing signal transmit power limit Under this power limit, the maximum of the system sensing mutual information in Step 1 is computed: wherein E x is a perceived signal energy limit; In step 2, the maximum value of the system perception mutual information is calculated by using the Lagrange multiplier method to construct a constraint function; the constraint function is as follows:

2. The method of claim 1, wherein the method is characterized by, Step 3 is as follows: the maximum value of the system perception mutual information obtained in step 2 is used to calculate the system perception link noise r(f) and the injection level A: And the injection water method is used to calculate the perception signal power spectrum distribution: | X s (f)| 2 = max[0, A - r(f)] (6).

3. The water-filling based optical downlink communication-aware integrated waveform design method of any one of claims 1-2, wherein: In step 2, the perception signal power limit is determined by the system transmission end device parameters.

4. The method of claim 1-2, wherein the method is characterized in that, Step 5 is as follows: the perception signal obtained in step 4 is added to the system communication signal to generate a corresponding electrical signal, which is modulated into an optical signal by an optical modulator and coupled into an optical fiber for transmission.

5. The method for designing an integrated waveform for optical fiber communication and sensing based on water injection as claimed in any one of claims 1 to 2, wherein: Step 6 is as follows: after the optical signal is transmitted through the optical fiber and affected by the perception target, the communication signal is filtered out at the communication receiving end, received by the optical communication receiver and the communication information is obtained; at the perception receiving end, the perception signal is filtered out, received by the optical perception receiver and the perception target information is obtained.

6. A system for optical downlink communication-aware integrated waveform design based on water-filling, configured to perform the method according to any one of claims 1 to 5, characterized in that The following modules are included: The transmission module combines the communication signal power spectrum distribution of the communication and perception integrated system under the optical fiber communication, the optical fiber channel dispersion, the channel noise power spectrum distribution and the unit impulse response of the perception target to calculate the system perception mutual information; the maximum value of the system perception mutual information is calculated in combination with the system perception signal transmission power limit; the maximum value of the system perception mutual information is used to calculate the system perception link noise and the injection level, and the injection water method is used to calculate the perception signal power spectrum distribution; the system perception signal waveform is selected, and the parameters are set to make the power spectrum distribution consistent with the perception signal power spectrum distribution obtained, to obtain the system perception signal; the obtained perception signal is added to the system communication signal to generate a corresponding electrical signal, which is modulated into an optical signal and transmitted through an optical fiber to the receiving module; The receiving module: after the optical signal is transmitted through the optical fiber and is affected by the sensing target, the communication signal is filtered out at the communication receiving end, and the communication information is received by the optical communication receiver; at the sensing receiving end, the sensing signal is filtered out, and the sensing target information is received by the optical sensing receiver.

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