Light flux and inductance energy integrated system and transmitted waveform design method

Abstract

The invention discloses an optical flux-inductance-energy integrated system and a transmitted waveform design method, and the method comprises the steps: carrying out the MLS modulation and OFDM modulation of an input original signal, obtaining an MLS waveform and an OFDM waveform, carrying out the amplitude distribution of the two waveforms, and combining the two waveforms according to a time sequence to form an MLS-OFDM AC signal; after the alternating current signal is subjected to digital-to-analog conversion, outputting the alternating current signal according to a set driving peak-to-peak value voltage, superposing a direct current component in the alternating current signal so as to carry out alternating current and direct current amplitude distribution, and outputting an analog electric signal; the transmitter converts analog electric signals into optical signals, and the optical signals are simultaneously connected with the information decoding module, the sensing processing module and the energy collecting module. According to the hybrid MLS-OFDM waveform design scheme combining alternating-current amplitude distribution and alternating-current and direct-current amplitude distribution, flexible balance among communication, perception and energy collection performance in an optical flux-inductance-energy integrated system is achieved, the complexity of the system can be reduced, and the system is made to be lighter and more compact.

Description

Technical Field

[0001] This invention relates to improvements in optical communication sensing technology, specifically to an integrated optical communication sensing system and a method for designing transmitted waveforms, belonging to the field of wireless optical communication technology. Background Technology

[0002] Industrial Internet of Things (IIoT) devices have been widely applied in smart manufacturing, intelligent inspection, and other scenarios. Sensor-Integrated Communication (ISAC), utilizing the same wireless signal to transmit information to users while simultaneously processing echo signals to perceive the surrounding environment and targets, is considered a key technological paradigm for various intelligent applications. However, the rapid increase in the number of IIoT nodes has brought severe challenges to equipment maintenance and sustainable power supply, especially in remote, extreme, or deep-sea environments where frequent human access is difficult. Wireless Power Transfer (WPT) provides an effective path for the continuous operation of large-scale low-power IIoT devices. Sixth-generation (6G) wireless networks are expected to provide enhanced communication data rates and high positioning accuracy for large-scale low-power IIoT devices in a sustainable manner. Based on this, sensor-integrated communication technology has emerged, aiming to simultaneously provide high-speed communication, centimeter-level sensing accuracy, and sustainable power supply, achieving integrated gains through hardware reuse, spectrum sharing, and functional reciprocity. At the same time, the rapid increase in mobile data traffic year by year and the increasingly scarce radio frequency spectrum have created a sharp contradiction. Optical wireless transmission has natural advantages in terms of spectrum resources, sensing accuracy and energy efficiency, and is regarded as an important technology paradigm for 6G fronthaul, thus promoting the development of Optical-Integrated Communication-Sensing-Power (O-ICSPT).

[0003] The transmitted waveform of an optical-sensing-integrated communication system (O-ISAC) can be viewed as first generating an alternating current (AC) waveform for communication and sensing, and then coupling it with a direct current (DC) component to achieve energy transfer. The design of the AC waveform is essentially a waveform design problem for O-ISAC. For O-ISAC, various waveform design schemes have been proposed, including pulse sequence sensing combined with pulse position modulation (PAM), orthogonal frequency division multiplexing (OFDM), hybrid PAM-OFDM, and OFDM mosaic maximum length sequence (MLS). Generally speaking, waveforms based on OFDM are more suitable for communication, while pulse-based waveforms are more suitable for sensing requirements. It is worth noting that among numerous codes and sequences, MLS is widely used in various sensing systems due to its excellent cross-correlation properties. The design of the AC-DC coupled waveform corresponds to the waveform design problem of the optical signal-energy simultaneous transmission system (SLIPT). Currently, there is a lack of work systematically exploring the impact of resource allocation between AC and DC on the overall performance of signal-energy simultaneous transmission.

[0004] Therefore, the performance of each functional module in an integrated optical communication, sensing, and energy system largely depends on the design of the transmitted waveform; however, this aspect has not yet been studied. In existing integrated optical communication, sensing, and energy architectures, pure-OFDM sequences are used as AC waveforms, leading to a synergistic effect between communication and sensing, thus making it impossible to achieve a flexible trade-off between the two. Furthermore, using a beam splitter to achieve the trade-off between sensing and energy harvesting inevitably increases the system's complexity. Summary of the Invention

[0005] To address the limitations of existing integrated optical communication, sensing, and energy harvesting architectures in achieving flexible trade-offs between communication and sensing functions, as well as the complexity of hardware facilities, this invention provides an integrated optical communication, sensing, and energy harvesting system and a method for designing transmission waveforms. This invention combines an AC-to-AC amplitude distribution scheme with an AC-to-DC amplitude distribution scheme to achieve a flexible trade-off between communication, sensing, and energy harvesting performance in the integrated optical communication, sensing, and energy harvesting system. At the same time, this invention can reduce system complexity, making it lighter and more compact.

[0006] The technical solution of this invention is implemented as follows:

[0007] An integrated optical-sensing-energy system includes a sensing signal generator, a digital-to-analog converter (DAC), a transmitter, an information decoding module, an energy harvesting module, and a sensing processing module for generating integrated sensing digital signals. The sensing signal generator, DAC, and transmitter are located at the transmitting end, while the information decoding module and energy harvesting module are located at the receiving end. A DC signal superposition module is provided between the DAC and the transmitter. The sensing signal generator includes an MLS modulation unit, an OFDM modulation unit, and a waveform mixing unit. The MLS modulation unit generates an MLS waveform using a linear feedback shift register based on primitive polynomials, and the OFDM modulation unit modulates the input original signal to obtain an OFDM waveform. The waveform mixing unit is used to perform amplitude distribution and timing combination of the MLS waveform modulated by the MLS modulation unit and the OFDM waveform modulated by the OFDM modulation unit to form an MLS-OFDM AC signal. After the MLS-OFDM AC signal is converted by the digital-to-analog converter, it is output with a set driving peak-to-peak voltage and enters the DC signal superposition unit. The DC signal superposition unit superimposes a DC component into the MLS-OFDM AC signal to perform AC / DC amplitude distribution. The DC signal superposition unit outputs the analog electrical signal after AC / DC amplitude distribution. The transmitter is used to convert the analog electrical signal into an optical signal. The optical signal is simultaneously connected to the information decoding module, the sensing processing module, and the energy harvesting module.

[0008] Furthermore, the sensing processing module includes a light reflector, a photodiode II, and an analog-to-digital converter (ADC). The reflector is located at the receiving end, and the photodiode II and ADC are located at the transmitting end. The light beam reflected by the light reflector is converted into an analog electrical signal by the photodiode II, and the analog electrical signal is converted into a digital signal by the ADC. The original MLS-OFDM AC signal output by the sensing signal generator is connected to the upsampling module. The upsampling module upsamples the time-domain samples of the MLS-OFDM AC signal generated by the sensing signal generator at the same upsampling rate. The output of the upsampling module and the output of the ADC are respectively connected to the cross-correlation module. The cross-correlation module uses a time-domain cross-correlation method to perform distance measurement using the time-domain samples of the MLS-OFDM AC signal generated by the sensing signal generator and the MLS-OFDM AC signal converted by the ADC to achieve sensing capability.

[0009] Furthermore, the information decoding module includes a photodiode I, an analog-to-digital converter, and an OFDM demodulation module. A portion of the optical signal is converted into an analog electrical signal by the photodiode I, and the analog electrical signal is converted into a digital signal by the analog-to-digital converter. This digital signal enters the OFDM demodulation module. In the OFDM demodulation module, the digital signal is synchronized and the cyclic prefix is ​​removed. Then, a frequency domain symbol is obtained through a fast Fourier transform. This frequency domain symbol is used to compensate for channel distortion through channel estimation and equalization, and then orthogonal amplitude modulation demapping is performed to recover the original communication data.

[0010] Furthermore, the energy harvesting module is a photovoltaic cell, which converts a portion of the light signal into electrical energy.

[0011] The transmitter is a laser diode.

[0012] This invention also provides a method for designing the transmission waveform of an integrated optical communication and sensing system, which is carried out according to the following steps:

[0013] 1) MLS modulation and OFDM modulation are performed on the original signal respectively to obtain MLS waveform and OFDM waveform;

[0014] 2) Perform AC amplitude distribution on the MLS waveform and OFDM waveform and combine them according to the timing sequence to form an MLS-OFDM AC signal;

[0015] 3) After the MLS-OFDM AC signal is converted by the digital-to-analog converter, it is output with the set driving peak-to-peak voltage, and a DC component is superimposed on the MLS-OFDM AC signal after digital-to-analog conversion to perform AC / DC amplitude distribution, so as to obtain the analog electrical signal used to drive the transmitter.

[0016] 4) The analog electrical signal is converted into an optical signal by the transmitter, and the optical signal is the transmitted waveform of the integrated optical communication and sensing system; the transmitted waveform is processed accordingly to realize information decoding, sensing processing and energy harvesting.

[0017] Furthermore, the MLS waveform is generated using a linear feedback shift register based on primitive polynomials; the OFDM waveform is generated by performing Hermitian symmetry before the inverse fast Fourier transform.

[0018] Furthermore, let the length of the MLS-OFDM AC signal be L. s The MLS waveform is denoted as s. MLS The length is L MLS OFDM waveform is denoted as s OFDM The length is L s -L MLS The MLS-OFDM AC signal is denoted as .

[0019] ;

[0020] The peak-to-peak voltage Vpp of the MLS waveform is defined as follows:

[0021] ;

[0022] The peak-to-peak voltage Vpp of the OFDM waveform is defined as follows:

[0023] ;

[0024] Let p1 represent the amplitude distribution ratio between the MLS waveform and the OFDM waveform.

[0025] ;

[0026] Let the amplitude of the DC component be denoted as A1; and the amplitude of the MLS-OFDM AC signal be denoted as A2, where A2 is Vpp. MLS and Vpp OFDM The larger value in the range, i.e., A2 = max(Vpp) MLS Vpp OFDM Let p2 represent the amplitude distribution ratio between the MLS-OFDM AC signal and the DC component;

[0027] ;

[0028] The waveform actually transmitted by the transmitter is represented as follows:

[0029] ;

[0030] Among them, A th and A max These represent the transmitter's turn-on voltage and saturation voltage, respectively.

[0031] By changing the amplitude allocation ratio p1 to adjust the performance trade-off between communication and sensing; by changing the amplitude allocation ratio p2 to adjust the performance trade-off between sensing and energy harvesting; and by simultaneously changing the amplitude allocation ratios p1 and p2 to adjust the transmitted waveform of the integrated optical-communication-sensing-energy system, the performance of communication decoding, sensing processing, and energy harvesting in the integrated optical-communication-sensing-energy system can be changed as needed, thereby achieving a flexible balance among the three.

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

[0033] This invention proposes a novel hybrid MLS-OFDM waveform integrated optical communication, sensing, and energy harvesting framework. The waveform design method of this invention overcomes the inherent limitation of Pure-OFDM waveforms in flexibly balancing communication and sensing performance, while fully utilizing the strong pulse autocorrelation characteristics of MLS to enhance sensing performance. This framework enables a lighter and more compact hardware design while supporting trade-offs between sensing and energy harvesting performance.

[0034] This invention further proposes a combined AC-to-AC and AC-to-DC amplitude allocation scheme to support flexible performance trade-offs among functional modules in an integrated optical communication, sensing, and energy harvesting system. AC amplitude allocation is performed between MLS and OFDM; adjusting this amplitude ratio achieves a performance trade-off between communication and sensing. AC-to-DC amplitude allocation is performed between the AC and DC components; adjusting this amplitude ratio achieves a performance trade-off between sensing and energy harvesting. Considering practical non-ideal factors, the two amplitude ratios jointly determine the transmission waveform of the integrated optical communication, sensing, and energy harvesting system, thereby achieving a flexible performance trade-off among the three functions.

[0035] The invention emits light without beam splitting, directly and simultaneously illuminating the communication, sensing, and energy harvesting modules. The sensing and processing uses a reflector to collect the light signal, thereby avoiding the use of a beam splitter, reducing system complexity, and making it lighter and more compact. Attached Figure Description

[0036] Figure 1 This is a system framework diagram of the hybrid MLS-OFDM waveform O-ICSPT of the present invention;

[0037] Figure 2 This is a schematic diagram illustrating the waveform design criteria based on MLS-OFDM of the present invention.

[0038] Figure 3This is an example diagram showing the waveform design results of the present invention;

[0039] Figure 4 This is a schematic diagram of the experimental setup for the O-ICSPT system of the present invention;

[0040] Figure 5 This diagram illustrates the performance of the O-ICSPT system under different DC and Vpp settings according to the present invention. (a)-(c) show the relationship between system performance and DC (Vpp=2V); (d)-(f) show the relationship between system performance and Vpp (DC=5.6V).

[0041] Figure 6 This is a schematic diagram of the system performance profile of the present invention as DC and Vpp vary; where (a)-(c) represent the MLS-OFDM (p1=0.6) proposed in this invention; and (d)-(f) represent the existing Pure-OFDM.

[0042] Figure 7 The diagram shows the performance of the O-ICSPT system under different amplitude distribution ratios according to the present invention; wherein, (a) shows the relationship between system performance and p1 (Vpp=2V, p2=2.8); (b) shows the relationship between system performance and p2 (Vpp=2V, p1=0.6); and (c) shows the technical details corresponding to the marked points in (b).

[0043] Figure 8 This is a schematic diagram of the system performance profile of the present invention as p1 and p2 change; where (a)-(c) represent a fixed DC (DC=5.6V); and (d)-(f) represent a fixed Vpp (Vpp=2V). Detailed Implementation

[0044] The implementation and principle of the present invention will be further described in detail below with reference to the accompanying drawings.

[0045] I. Framework of the Integrated Optical Communication and Sensing System

[0046] The integrated system framework of the hybrid MLS-OFDM waveform optical communication sensing of the present invention is as follows: Figure 1As shown, the system includes a transmitter and a receiver. A sensing signal generator, a digital-to-analog converter, and a transmitter are located on the transmitter, while an information decoding module and an energy harvesting module are located on the receiver. Compared to traditional integrated optical-sensing-energy architectures, the AC waveform of this invention is no longer a Pure-OFDM sequence, but a time-domain combination of MLS and OFDM sequences. Pure-OFDM sequences bind communication and sensing performance, making it impossible to achieve a flexible performance trade-off between the two. In contrast, the hybrid MLS-OFDM waveform not only supports continuously adjustable trade-offs between communication and sensing performance, but also leverages the strong pulse autocorrelation characteristics of MLS sequences to improve sensing performance. Furthermore, the framework proposed in this invention avoids the use of beam splitters without sacrificing system flexibility, thus achieving a lighter and more compact system design.

[0047] Specifically, at the transmitting end, the sensing signal generating device first generates an MLS waveform using a linear feedback shift register based on primitive polynomials via an MLS modulation unit. Then, an OFDM modulation unit modulates the input original binary bit sequence signal to obtain an OFDM waveform. Subsequently, a waveform mixing unit performs amplitude distribution on the MLS and OFDM waveforms and combines them sequentially to form an MLS-OFDM AC signal. This MLS-OFDM AC signal is then converted from a digital-to-analog (D / A) converter and output at a set driving peak-to-peak voltage (Vpp). A DC component is then superimposed on this AC signal by a DC signal superposition unit to perform AC-DC amplitude distribution, resulting in an analog electrical signal used to drive the transmitter (in this example, a laser diode LD). The transmitter converts the analog electrical signal into an optical signal. The optical signal actually emitted by the transmitter is the final transmitted waveform. The AC component simultaneously carries communication and sensing information, while the DC component provides the main source for energy harvesting. Therefore, the light wave emitted by the LD integrates communication, sensing, and energy harvesting functions.

[0048] This invention employs two photodiodes (PDs) as photoelectric converters for information decoding and sensing processing, and one photovoltaic cell (PV) as a photoelectric converter for energy harvesting. The cutoff frequency of a PV cell is typically only a few hundred hertz to several megahertz, which severely limits the usable sampling rate of the D / A conversion. A low D / A conversion sampling rate not only makes it difficult to support high-speed communication but also significantly reduces sensing accuracy, as distance resolution depends on the sampling rate of the analog-to-digital (A / D) conversion. Although the A / D conversion sampling rate can be higher than the D / A conversion sampling rate, if the upsampling factor is too large when the receiver upsamples the signal, it will introduce significant interpolation errors and spectral artifacts, leading to a decrease in waveform reconstruction and time delay estimation accuracy. The hybrid PD / PV photoelectric conversion maximizes the advantages of each, simultaneously supporting high-speed communication, high-precision sensing, and efficient energy harvesting.

[0049] (1) Information Decoding Module: The information decoding module includes photodiode I, an analog-to-digital converter, and an OFDM demodulation module. A portion of the optical signal is detected by photodiode I at the receiving end and converted into an analog electrical signal. This analog electrical signal is then converted into a digital signal via an A / D converter, and the digital signal enters the OFDM demodulation module. Synchronization processing is performed in the OFDM demodulation module, including sequentially performing Fast Fourier Transform (FFT), channel estimation and equalization, and Quadrature Amplitude Modulation (QAM) demapping operations on the extracted OFDM signal to recover the original communication data. and Let the transmitted and recovered binary bits represent the data respectively. The performance of the information decoding module can then be evaluated by the bit error rate (BER).

[0050]

[0051] Where N represents the length of the communication bit sequence.

[0052] (2) Sensing Processing Module: The sensing processing module includes a light reflector, a photodiode II, and an analog-to-digital converter; the light reflector is located at the receiving end, and the photodiode II and the analog-to-digital converter are located at the transmitting end. In this embodiment, the light reflector is a corner cube reflector (CCR). A portion of the light beam is reflected back to the transmitting end by the corner cube reflector (CCR), detected by the photodiode II, and converted into an analog electrical signal, which is then converted into a digital signal by an A / D converter. The original MLS-OFDM AC signal output by the sensing signal generator is connected to the upsampling module. The upsampling module upsamples the time-domain samples of the MLS-OFDM AC signal generated by the sensing signal generator at the same upsampling rate. The output of the upsampling module and the output of the analog-to-digital converter are respectively connected to the cross-correlation module. The cross-correlation module uses the time-domain cross-correlation method to measure the distance using the time-domain samples of the MLS-OFDM AC signal generated by the sensing signal generator and the MLS-OFDM AC signal converted by the analog-to-digital converter to achieve sensing capability.

[0053] To estimate the distance between the transmitter and receiver, the reflected MLS-OFDM AC signal and an upsampled version of the original MLS-OFDM signal need to be cross-correlated to complete the Time-of-Flight (ToF) measurement. Let x(n) and y(n) be the distances between the transmitter and receiver. s (n) represents the time-domain sample of the original MLS-OFDM AC signal after upsampling and the time-domain sample of the reflected MLS-OFDM AC signal, respectively. The maximum likelihood estimate of ToF can then be expressed as:

[0054]

[0055] Among them, Lw It is the length of the time-domain window chosen for cross-correlation. The estimated distance is determined by... Given, among which m / s represents the speed of light. The performance of the sensing and processing module is evaluated using the root mean square error (RMSE) of the ranging measurement.

[0056]

[0057] Where d is the actual distance between the transmitter and receiver, and K is the number of measurement samples. Let the sampling rate of the A / D conversion be f. s If (Sa / s), then the ranging resolution is m.

[0058] (3) Energy Harvesting Module: The energy harvesting module is a photovoltaic (PV) cell. A portion of the light beam is detected by the PV and converted into DC output. According to the DC equivalent circuit model of the PV, its output current is expressed as...

[0059]

[0060] Among them, I ph Represents the photocurrent generated by the incident light; I0 ​​is the reverse saturation current of the diode, and its value depends on the irradiance and temperature; R SH R represents leakage resistance, used to characterize leakage paths caused by junction impurities and defects in the photovoltaic cell crystal structure; S This represents series resistance, which originates from sources including welded contacts, battery interconnect structures, and resistive losses within semiconductor materials; R L This is the external load resistor.

[0061] When the incident light power is given, I ph 、I0、R SH and R S It can be considered a constant. The output voltage and current of PV satisfy... And with R L The output power of a PV changes dynamically with the changes in the environment. .like Figure 1 As shown in the energy harvesting module, the output power of the photovoltaic cell exhibits a significant nonlinear characteristic if and only if the load resistance R L Set to the optimal value R L,opt hour( Only then can the maximum value be reached. The energy collected at this point (HE) is calculated as follows:

[0062]

[0063] Among them, V mpp and Impp Let A be the output voltage and output current of PV at the maximum power point, respectively. e Let represent the effective detection area of ​​PV, then the energy harvesting density of the O-ICSPT system is expressed as:

[0064]

[0065] It characterizes the energy extraction capacity per unit area PV at the maximum power point.

[0066] II. Waveform Design Principles

[0067] In an integrated optical communication, sensing, and energy system, the performance of each functional module largely depends on the transmitted waveform. To achieve a flexible performance trade-off among communication, sensing, and energy to adapt to the needs of different application scenarios, this invention proposes a two-stage amplitude allocation strategy combining AC-to-AC and AC-DC methods. Detailed waveform design guidelines are as follows: Figure 2 As shown. The length of the mixed AC sequence is denoted as L. s Increasing the time proportion of pulses in a hybrid AC sequence can enhance the autocorrelation characteristics of the sequence, thereby improving sensing performance. However, pulse sequences such as MLS do not carry communication information, and increasing their proportion will affect the communication payload. The time period allocation of the hybrid AC sequence needs to be balanced between sensing performance and communication rate. The time period allocation of the hybrid AC sequence is not within the scope of this invention. When the pulse sequence occupies 25% of the total AC sequence, the sensing performance can be significantly improved. In order to enhance sensing performance without excessively sacrificing communication data rate, this invention uses an MLS-OFDM hybrid AC sequence with a sequence length ratio of 1:3 as an example to illustrate the proposed two-stage amplitude allocation waveform design scheme.

[0068] Bipolar MLS (denoted as s) MLS The real-valued bipolar OFDM sequence (denoted as s) is generated using a linear feedback shift register based on primitive polynomials. OFDM This is achieved by performing Hermitian-symmetric generation before the inverse fast Fourier transform (IFFT). Let the MLS waveform length be L. MLS Then the OFDM waveform length is L s -L MLS Therefore, the MLS-OFDM AC signal is denoted as,

[0069]

[0070] The Vpp definition of MLS is

[0071]

[0072] Vpp of an OFDM sequence is defined as

[0073]

[0074] Let p1 represent the amplitude ratio between MLS and OFDM sequences.

[0075]

[0076] Vpp OFDM Normalization shows that as p1 increases, the amplitude and power ratio of the MLS gradually increase, while the amplitude and power ratio of the OFDM sequence decrease accordingly.

[0077] The DC component, as the primary source of energy harvesting, has an amplitude denoted as A1. The amplitude of the AC signal, A2, is Vpp. MLS and Vpp OFDM The larger value in the range, i.e., A2 = max(Vpp) MLS Vpp OFDM Let p2 represent the amplitude distribution ratio between AC and DC.

[0078]

[0079] When A1 is fixed, A2 decreases as p2 increases; when A2 is fixed, A1 increases as p2 increases. In waveform design, practical non-ideal factors such as cutoff and saturation clipping must be considered: if A1 is too small, the negative AC signal will not reach the LD's turn-on voltage, resulting in cutoff clipping; if A1 is too large, the positive AC signal will enter the LD's saturation range, leading to saturation clipping. Therefore, the actual waveform emitted by the LD can be represented as follows:

[0080]

[0081] Among them, A th and A max These represent the turn-on voltage and saturation voltage of the LD, respectively.

[0082] The amplitude allocation ratios p1 and p2 jointly determine the performance of the communication, sensing, and energy harvesting modules in an integrated optical-communication-sensing-energy system. By adjusting these two parameters, a flexible performance trade-off can be achieved among the three functions. Figure 3 Representative waveform design results are presented under the condition of fixed p1 and p2, where the AC signal amplitude A2 is set to 1 and the cutoff voltage A th and saturation voltage A max They were set to 2.8 and 4.2 respectively. It can be observed that when p1 is small, Vpp...MLS <Vpp OFDM At this point, p2 has a more significant impact on the OFDM sequence. When p2 is small, the portion of the OFDM sequence below the LD turn-on voltage undergoes cutoff pruning; when p2 is large, the portion above the saturation voltage undergoes saturation pruning. As p1 increases, Vpp MLS With Vpp OFDM When approaching a certain threshold, both MLS and OFDM sequences will experience cutoff or saturation distortion. As p1 increases further, Vpp... MLS >Vpp OFDM At this time, the effect of p2 is mainly reflected in the MLS. A smaller p2 causes the low amplitude portion to be cut off, while a larger p2 causes the high amplitude portion to enter the saturation range. These results clearly demonstrate the significant impact of the amplitude distribution ratios p1 and p2 on the transmitted waveform of the optical communication and sensing integrated system, and the performance of each functional module is highly dependent on the shape of this transmitted waveform.

[0083] III. Verification of Examples

[0084] To clearly describe the beneficial effects of a flexible hybrid waveform optical communication and energy sensing integrated system with combined AC-DC amplitude distribution, the following embodiments are provided to comprehensively evaluate the proposed optical communication and energy sensing integrated system. A hardware experimental platform for the optical communication and energy sensing integrated system was built for conceptual experimental verification. The system block diagram and experimental setup are shown below. Figure 4 As shown.

[0085] First, a hybrid MLS-OFDM signal was generated offline in MATLAB and loaded into an arbitrary waveform generator (AWG, UNI-T UTG9604T) to complete the D / A conversion. Unlike traditional optical wireless experimental platforms, to ensure the consistency of the dimensions of A1 and A2, this experiment did not use a bias circuit to provide DC bias; AC amplification and AC-DC superposition were both directly implemented within the AWG. Specifically, after D / A conversion, the MLS-OFDM signal was set to a certain Vpp (unit: V) and a DC component (unit: V) was superimposed. Subsequently, a red light LD (Ushio HL63603TG) was driven to transmit the optical signal.

[0086] After propagating in free space, the light beam is used for communication, energy harvesting, and ranging at the receiving end. The receiving end integrates an avalanche photodiode (APD, Hamamatsu C12702-11), a PV (Triple-junction GaAs), and a CCR (Thorlabs PS976). A portion of the optical power is detected by the APD and converted into an electrical signal. This signal is sampled and recorded by an oscilloscope (OSC, Tektronix MDO32) and transmitted to an offline module for communication signal demodulation. Another portion of the optical power is absorbed by the PV and converted into DC power, which is impedance matched by a sliding rheostat and its electrical conductivity (HE) is measured by a digital power meter (Chroma 66205). A third portion of the beam is reflected back to the transmitter by the CCR, received by another APD of the same model, converted into an electrical signal, sampled and recorded by an oscilloscope (Tektronix MDO3034), and its Time-of-Flight (ToF) is estimated through cross-correlation to obtain the distance between the transmitter and receiver.

[0087] Detailed experimental parameters are as follows: number of data subcarriers: 31; FFT / IFFT size: 64; AWG sampling rate: 250 MSa / s; OSC sampling rate: 2.5 GSa / s; APD photosensitive area: 1 mm². 2 The CCR diameter is 50 mm; the PV photosensitive area is 1 cm². 2 The upsampling rate is 10; the distance between the transmitter and receiver is 1.75 m. Therefore, the effective communication bandwidth is 250 × 31 / 64 = 121.09 MHz. The ranging resolution is 3 × 10⁻⁶. 8 / (2×2.5×10 9 ) m.

[0088] In the experiment, Vpp and DC correspond to the AC signal amplitude A1 and DC component amplitude A2, respectively. All energy harvesting results were measured under optimal external load resistance conditions. The traditional Pure-OFDM waveform was used as a benchmark for comparison.

[0089] DC and Vpp are two important experimental parameters that can be directly adjusted in the experiment. Figure 5(a)–(c) show the performance changes of the O-ICSPT system when DC is changed under a fixed Vpp condition. Optical power increases with increasing DC. When DC is small, the overall optical power is weak and low-amplitude AC signals easily fall into the cutoff region of the LD, resulting in significant cutoff clipping; when DC is too large, high-amplitude AC signals enter the saturation region, producing saturation clipping. Therefore, the BER performance of both MLS-OFDM and the traditional Pure-OFDM optical sensing and sensing integrated system initially improves and then deteriorates. Because MLS-OFDM allocates part of the AC amplitude budget to the MLS, its BER performance is not as good as the Pure-OFDM optical sensing and sensing integrated system. For the sensing module, the nonlinear distortion caused by cutoff and saturation clipping also deteriorates the autocorrelation structure of the MLS-OFDM waveform, causing the RMSE performance to show a similar trend of initially improving and then deteriorating. Due to the superior pulse autocorrelation characteristics of the MLS sequence, the ranging capability of the MLS-OFDM optical sensing and sensing integrated system is significantly better than that of the Pure-OFDM optical sensing and sensing integrated system. For the energy harvesting module, the DC component is the decisive contributor, and therefore the HE increases continuously as DC increases. Figure 5 (d)-(f) show the performance changes when Vpp is changed under fixed DC conditions. BER and RMSE still show a trend of first improving and then deteriorating; while energy harvesting does not change significantly in this case because Vpp regulates AC power and has little effect on the DC output of PV.

[0090] Figure 6 Performance contour lines for an MLS-OFDM (p1=0.6) integrated optical communication, sensing, and energy harvesting system and a Pure-OFDM integrated optical communication, sensing, and energy harvesting system are presented under different DC and Vpp conditions. Communication and sensing exhibit optimal operating regions, while energy harvesting does not. (Comparison) Figure 6 (a)(b) and Figure 6 (d)(e) Although the Pure-OFDM optical-sensing-energy integrated system has an advantage in BER performance, its RMSE performance is far inferior to that of the MLS-OFDM optical-sensing-energy integrated system. Figure 6 (c) Figure 6 (f) further shows that the AC waveform has almost no effect on energy harvesting.

[0091] Subsequently, the present invention verified the effectiveness of the proposed joint AC-AC and AC-DC amplitude distribution waveform design scheme. Figure 7 The performance variations of the O-ICSPT system under different amplitude allocation ratios are shown. Figure 7As shown in (a), when Vpp and p2 are fixed, the effective power allocated to the OFDM gradually decreases as p1 increases, leading to a continuous deterioration in BER performance. Meanwhile, the effective power of the MLS increases with p1, but the RMSE does not continuously decrease; instead, it shows a trend of first decreasing and then increasing. This is because when the peak-to-peak value of the MLS is significantly higher than that of the OFDM, the waveform is more susceptible to nonlinear clipping distortion. Since p1 only adjusts the AC amplitude distribution, it has almost no effect on energy harvesting. Figure 7 In (b), increasing p2 under the condition of fixed Vpp and p1 is equivalent to increasing the DC component. The optical power increases with the increase of p2, but excessive DC will cause the waveform to enter the saturation range of LD, resulting in nonlinear distortion. Therefore, both BER and RMSE show an initial improvement followed by a deterioration, while HE continues to increase with the increase of p2. Figure 7 (c) demonstrates Figure 7 (b) details corresponding to the marked points, including the receiver constellation diagram of the communication module, the cross-correlation peak shape of the sensing module, and the optimal external load resistance matching process of the energy harvesting module.

[0092] Figure 8 Performance contour lines of the MLS-OFDM integrated optical communication, sensing, and energy harvesting system under different p1 and p2 conditions are presented. It can be observed that both communication and sensing performance are highly sensitive to the amplitude distribution ratios between AC and AC-DC sensors. Energy harvesting performance is insensitive to the amplitude distribution ratio between AC sensors but sensitive to the AC-DC amplitude distribution ratio. For communication and energy harvesting functions, there is no optimal value for p1, but there is an optimal value for p2. Unlike communication and energy harvesting functions, for sensing functions, both p1 and p2 exhibit optimal performance ranges. Therefore, by jointly adjusting p1 and p2, a flexible and continuously adjustable trade-off can be achieved among communication, sensing, and energy harvesting. The experimentally measured data rate is approximately 181.64 Mbps, the minimum distance range RMSE is approximately 1 cm, and the energy harvesting capability is approximately 5.2 W / m². 2 .

[0093] Figure 5 and Figure 6 Experimental results show that the MLS-OFDM integrated optical communication and sensing system proposed in this invention utilizes the excellent autocorrelation characteristics of the MLS sequence to enhance sensing performance and supports a continuously adjustable trade-off between communication and sensing, which is impossible for the Pure-OFDM integrated optical communication and sensing system. Furthermore, as... Figure 7 and Figure 8 As shown, the combined AC-to-AC and AC-DC amplitude distribution waveform design can flexibly adjust communication, sensing, and energy harvesting performance to adapt to different application requirements.

[0094] Finally, it should be noted that the above examples of the present invention are merely illustrative and not intended to limit the implementation of the invention. Although the applicant has described the present invention in detail with reference to preferred embodiments, those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. An integrated optical-sensing-energy system, comprising a sensing signal generator, a digital-to-analog converter, a transmitter, an information decoding module, an energy harvesting module, and a sensing processing module for generating integrated sensing digital signals; the sensing signal generator, digital-to-analog converter, and transmitter are disposed at the transmitting end, and the information decoding module and energy harvesting module are disposed at the receiving end; characterized in that: A DC signal superposition module is provided between the digital-to-analog converter and the transmitter. The sensing signal generation device includes an MLS modulation unit, an OFDM modulation unit, and a waveform mixing unit. The MLS modulation unit generates an MLS waveform using a linear feedback shift register based on primitive polynomials. The OFDM modulation unit modulates the input original signal to obtain an OFDM waveform. The waveform mixing unit performs amplitude distribution on the MLS waveform modulated by the MLS modulation unit and the OFDM waveform modulated by the OFDM modulation unit, and combines them in a timing sequence to form an MLS-OFDM AC signal. After being converted by the digital-to-analog converter, the MLS-OFDM AC signal is output with a set driving peak-to-peak voltage and enters the DC signal superposition unit. The DC signal superposition unit superimposes a DC component into the MLS-OFDM AC signal to perform AC / DC amplitude distribution. The DC signal superposition unit outputs an analog electrical signal after AC / DC amplitude distribution. The transmitter converts the analog electrical signal into an optical signal, which is simultaneously connected to an information decoding module, a sensing processing module, and an energy harvesting module.

2. The integrated optical and energy sensing system according to claim 1, characterized in that, The sensing processing module includes a light reflector, a photodiode II, and an analog-to-digital converter (ADC). The reflector is located at the receiving end, while the photodiode II and ADC are located at the transmitting end. The light beam reflected by the light reflector is converted into an analog electrical signal by the photodiode II, and the analog electrical signal is converted into a digital signal by the ADC. The original MLS-OFDM AC signal output from the sensing signal generator is connected to an upsampling module. The upsampling module upsamples the time-domain samples of the MLS-OFDM AC signal generated by the sensing signal generator at the same upsampling rate. The output of the upsampling module and the output of the ADC are connected to a cross-correlation module. The cross-correlation module uses a time-domain cross-correlation method to measure distance using the time-domain samples of the MLS-OFDM AC signal generated by the sensing signal generator and the MLS-OFDM AC signal converted by the ADC, thereby achieving sensing capability.

3. The integrated optical and energy sensing system according to claim 1, characterized in that, The information decoding module includes a photodiode I, an analog-to-digital converter, and an OFDM demodulation module. A portion of the optical signal is converted into an analog electrical signal by the photodiode I, and the analog electrical signal is converted into a digital signal by the analog-to-digital converter. This digital signal enters the OFDM demodulation module. In the OFDM demodulation module, the digital signal is synchronized and the cyclic prefix is ​​removed. Then, a frequency domain symbol is obtained through a fast Fourier transform. This frequency domain symbol is then subjected to channel estimation and equalization to compensate for channel distortion, and then orthogonal amplitude modulation demapping is performed to recover the original communication data.

4. The integrated optical and energy sensing system according to claim 1, characterized in that, The energy harvesting module is a photovoltaic cell, which converts a portion of the light signal into electrical energy.

5. The integrated optical and energy sensing system according to claim 1, characterized in that, The transmitter is a laser diode.

6. A method for designing the transmission waveform of an integrated optical communication and sensing system, characterized in that: Follow these steps: 1) MLS modulation and OFDM modulation are performed on the original signal respectively to obtain MLS waveform and OFDM waveform; 2) Perform AC amplitude distribution on the MLS waveform and OFDM waveform and combine them according to the timing sequence to form an MLS-OFDM AC signal; 3) After the MLS-OFDM AC signal is converted by the digital-to-analog converter, it is output with the set driving peak-to-peak voltage, and a DC component is superimposed on the MLS-OFDM AC signal after digital-to-analog conversion to perform AC / DC amplitude distribution, so as to obtain the analog electrical signal used to drive the transmitter. 4) The analog electrical signal is converted into an optical signal by the transmitter, and the optical signal is the transmitted waveform of the integrated optical communication and sensing system; the transmitted waveform is processed accordingly to realize information decoding, sensing processing and energy harvesting.

7. The method for designing the transmission waveform of an integrated optical communication and sensing system according to claim 6, characterized in that: The MLS waveform is generated using a linear feedback shift register based on primitive polynomials; the OFDM waveform is generated by performing Hermitian symmetry before the inverse fast Fourier transform.

8. The method for designing the transmission waveform of an integrated optical communication and sensing system according to claim 6, characterized in that: Let the length of the MLS-OFDM AC signal be L. s The MLS waveform is denoted as s. MLS The length is L MLS OFDM waveform is denoted as s OFDM The length is L s -L MLS The MLS-OFDM AC signal is denoted as . ； The peak-to-peak voltage Vpp of the MLS waveform is defined as follows: ； The peak-to-peak voltage Vpp of the OFDM waveform is defined as follows: ； Let p1 represent the amplitude distribution ratio between the MLS waveform and the OFDM waveform. ； Let the amplitude of the DC component be denoted as A1; and the amplitude of the MLS-OFDM AC signal be denoted as A2, where A2 is Vpp. MLS and Vpp OFDM The larger value in the range, i.e., A2 = max(Vpp) MLS Vpp OFDM Let p2 represent the amplitude distribution ratio between the MLS-OFDM AC signal and the DC component; ； The waveform actually transmitted by the transmitter is represented as follows: ； Among them, A th and A max These represent the transmitter's turn-on voltage and saturation voltage, respectively. By changing the amplitude allocation ratio p1 to adjust the performance trade-off between communication and sensing; by changing the amplitude allocation ratio p2 to adjust the performance trade-off between sensing and energy harvesting; and by simultaneously changing the amplitude allocation ratios p1 and p2 to adjust the transmitted waveform of the integrated optical-communication-sensing-energy system, the performance of communication decoding, sensing processing, and energy harvesting in the integrated optical-communication-sensing-energy system can be changed as needed, thereby achieving a flexible balance among the three.

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