Light flux and sensing energy integrated system

Abstract

The invention discloses a light flux-inductance-energy integrated system, which comprises a flux-inductance signal generating device for generating flux-inductance integrated digital signals, and is characterized in that the output of the flux-inductance signal generating device is connected with a digital-to-analog converter so as to convert the flux-inductance integrated digital signals into analog electric signals; an analog electric signal output by the digital-to-analog converter is connected with the transmitter through the driving circuit, and the analog electric signal is converted into an optical signal through the transmitter; an optical signal output by the emitter generates two light beams through the spectroscope; one light beam is connected with an information decoding module and a sensing processing module; and the other light beam is connected with the energy collection module for energy collection. The optical flux and inductance integrated system provided by the invention is simple to implement and easy to integrate with existing facilities, and can provide integrated gains such as shared hardware resources and reduced mutual interference.

Description

Technical Field

[0001] The present invention relates to an integrated optical communication, optical sensing and energy system, which can realize the system integration of optical communication, optical sensing and energy collection, and belongs to the technical field of wireless optical communication. Background Art

[0002] The sixth generation (6G) mobile communication is undergoing profound technological innovation and has become an important topic of global research. In order to meet the application needs of hundreds of millions of IoT devices and mobile users to achieve ultra-large-scale interconnection in the access network, 6G communication will fully tap the full spectrum resources including millimeter wave, terahertz, and optical frequency bands. In order to serve various vertical industries, communication, perception, and energy transmission will be deeply integrated, giving rise to full application scenarios such as interawareness integration (ISAC) and wireless signal-energy transmission. The communication network architecture is evolving towards multi-network integration, multi-functional integration, green, flexible and lightweight. Optical wireless communication (OWC) has a large range of unregulated spectrum resources from 3THz to 300PHz, including infrared, visible, and ultraviolet light. It also has many advantages such as high speed, no electromagnetic interference, easy integration, green energy saving, safety and reliability. In this context, optical integrated systems such as optical ISAC (O-ISAC) and lightwave signal-energy transmission (SLIPT) have received increasing attention.

[0003] The unique characteristics of optical front-ends and channels provide great advantages for communication and sensing. The O-ISAC system can fully utilize the large bandwidth of optical signals to achieve high-speed communication and high-resolution perception; it can work well in RF-sensitive areas and indoor and underground environments where satellite signals are blocked. A key challenge in serving a large and increasing number of smart nodes is the limited energy resources of wireless devices. Energy harvesting (EH) is considered a promising technical solution to extend the life of wireless networks.

[0004] A large number of IoT applications with broad application prospects, such as smart cities, smart grids, smart transportation, smart oceans, smart agriculture, and smart exploration, are constantly emerging, and mobile terminals have increasingly diversified requirements for service quality, such as high-speed transmission, high-precision sensing, and sustainable operation. OWC, optical sensing, or optical wireless power transmission systems with single functions can no longer meet the increasingly complex and diverse functional requirements. A large number of studies on O-ISAC and SLIPT have demonstrated the significant advantages of optical integrated systems, but only provide partial solutions, and there are still problems such as insufficient system flexibility, limited functional integration, and low resource utilization. In fact, whether it is OWC, optical sensing, or optical wireless power transmission, its optical front end such as driving circuits and light sources can be fully shared. Therefore, further integration of these three functions is an obviously more promising solution. However, more functional integration also introduces more complex resource allocation, interference management, and performance optimization. Resource allocation schemes for self-powered visible light communication and positioning systems based on active sensing have been proposed, but they are usually accompanied by high energy consumption and complex system design. At present, there is still a lack of research on optical communication, sensing, and energy integration (O-ICSPT) systems based on passive sensing. Furthermore, there has been no experimental study on the O-ICSPT system, and the parameter selection criteria for the actual system remains an open question.

[0005] Therefore, it is urgent to propose a universal O-ICSPT system framework, conduct conceptual experimental verification on it, and explore the influence of various experimental system parameters on the performance of each functional module. Summary of the invention

[0006] In view of the problems existing in existing optical integrated systems, such as insufficient system flexibility, limited functional integration, and low resource utilization, and the fact that self-powered visible light communication and positioning systems based on active perception are usually accompanied by high energy consumption and complex system design, the purpose of the present invention is to propose an optical communication, sensing and energy integrated system. The present invention is simple to implement and easy to integrate with existing facilities, and can provide integrated gains such as sharing hardware resources and reducing mutual interference.

[0007] The technical solution of the present invention is achieved in this way:

[0008] The optical-synaesthesia-energy integration system comprises a synaesthesia signal generating device for generating a synaesthesia-integrated digital signal, wherein the output of the synaesthesia signal generating device is connected to a digital-to-analog converter to convert the synaesthesia-integrated digital signal into an analog electrical signal, the analog electrical signal output by the digital-to-analog converter is connected to a transmitter through a driving circuit, and the analog electrical signal is converted into an optical signal through the transmitter; the optical signal output by the transmitter generates two light beams through a spectroscope; one light beam is connected to an information decoding module and a perception processing module; and the other light beam is connected to an energy collection module for energy collection.

[0009] Furthermore, the information decoding module includes a photodiode I, an analog-to-digital converter and an OFDM demodulation module. The light beam is converted into an analog electrical signal through the photoelectric converter, and the analog electrical signal is converted into a digital signal through the analog-to-digital converter. The digital signal enters the OFDM demodulation module; in the OFDM demodulation module, the digital signal is synchronized and the cyclic prefix is ​​removed, and then the frequency domain symbol is obtained through fast Fourier transform; the frequency domain symbol is compensated for channel distortion through channel estimation and equalization, and then orthogonal amplitude modulation demodulation is performed, that is, the original binary bit sequence is restored.

[0010] Furthermore, the light beam is connected to a perception processing module through a light reflector; the perception processing module includes a photodiode II and an analog-to-digital converter, the light beam reflected by the light reflector is converted into an analog electrical signal through the photoelectric converter, and the analog electrical signal is converted into a digital signal through the analog-to-digital converter; the output of the synaesthesia signal generating device is connected to an upsampling module, the upsampling module upsamples the time domain samples of the digital signal generated by the synaesthesia signal generating device at the same upsampling rate, the output of the upsampling module and the output of the analog-to-digital converter are respectively connected to a cross-correlation module, the cross-correlation module adopts a time domain cross-correlation method, and uses the digital signal generated by the synaesthesia signal generating device and the time domain samples of the digital signal converted by the analog-to-digital converter to perform ranging to achieve perception capability.

[0011] Furthermore, the energy collection module is a photoelectric converter; and the photoelectric converter is a photovoltaic cell.

[0012] Furthermore, the process of the synaesthesia signal generating device generating the synaesthesia integrated digital signal is as follows: firstly, the original binary bit sequence is orthogonal amplitude modulation mapped, and then a training sequence is inserted for channel estimation; then, Hermitian symmetry is applied and an inverse fast Fourier transform is performed to obtain a real-valued time domain signal; and the time domain signal is inserted with a cyclic prefix to obtain the synaesthesia integrated digital signal.

[0013] Preferably, the beam splitter is integrated on the transmitter or on the receiver.

[0014] Preferably, the emitter is a laser diode; and the light reflector is a corner cube reflector.

[0015] Preferably, when the light source generated by the laser diode is red light with a wavelength of 638 nm, the maximum data transmission rate, the minimum ranging root mean square error and the maximum energy collection can be achieved.

[0016] Preferably, the laser diode is a red laser diode, the optimal bias current of the red laser diode is 70mA, and the optimal driving Vpp is 100mV; or the laser diode is a green laser diode, the optimal bias current of the green laser diode is 50mA, and the optimal driving Vpp is 150mV; or the laser diode is a blue laser diode, the optimal bias current of the blue laser diode is 50mA, and the optimal driving Vpp is 200mV.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention proposes a novel O-ICSPT system framework. Communication and perception are achieved through an OFDM system based on reflected light. The method is simple to implement and easy to integrate with existing facilities. By splitting the optical power in the spatial domain, not only a flexible performance trade-off between the synaesthesia performance and the EH performance is achieved, but also photodiodes (PD) and photovoltaic (PV) cells are allowed to be used as photoelectric converters for signal detection and EH, respectively, which can maximize the respective advantages of PD and PV. The framework proposed in the present invention can serve as the basic framework for future theoretical research on O-ICSPT systems.

[0019] This paper makes the first proof of concept experiment of O-ICSPT system. The experimental platform built successfully achieves the communication performance of maximum data transmission rate of about 632.58Mbps, the perception performance of minimum ranging root mean square error (RMSE) close to 0 and the power transmission performance of maximum EH of about 10.012mW at the interaceptive link distance of 1.5m and EH link distance of 0.6m. It proves the application potential of the proposed optical interaceptive energy integrated system in the future multifunctional integrated communication network architecture.

[0020] The present invention determines the influence of experimental system parameters on the performance of each functional module of the O-ICSPT system. Through a comprehensive experimental study, the basic characteristics and performance influencing factors of the O-ICSPT system are clarified. The experimental conclusions on the performance of each functional module of the O-ICSPT system by the value of bias current, drive peak-to-peak voltage (Vpp) and the selection of light source wavelength are summarized, and the experimental conclusions obtained provide valuable practical experience for subsequent experimental research on the O-ICSPT system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 - Schematic diagram of the structure of the integrated light-sensing-energy system of the present invention; wherein, (a) O-ICSPT system framework; (b) OFDM modulation; (c) OFDM demodulation; (d) spectroscope model; (e) CCR model; (f) PV equivalent circuit.

[0022] Figure 2- Schematic diagram of the experimental device of the light-transmitting, sensing-energy-integrated system of the present invention.

[0023] Figure 3 -Characteristic curves of LDs of three different wavelengths of the present invention; among them, (a) VI characteristic curve; (b) PI characteristic curve.

[0024] Figure 4 -Amplitude spectrum of the received signal of the present invention; wherein, (a) red light LD; (b) green light LD; (c) blue light LD; (d) normalized frequency response curves of different LDs.

[0025] Figure 5 -VI characteristic curves of PV under different bias currents of the present invention; wherein, (a) red light LD; (b) green light LD; (c) blue light LD.

[0026] Figure 6 - BER, RMSE and EH performance curves of the present invention under different bias currents; wherein, (a)-(c) red light LD; (d)-(f) green light LD; (g)-(i) blue light LD.

[0027] Figure 7 - BER, RMSE and EH performance curves under different Vpp of the present invention; among them, (a)-(c) red light LD; (d)-(f) green light LD; (g)-(i) blue light LD.

[0028] Figure 8 - BER, RMSE and EH performance profiles of the present invention.

[0029] Fig. 9 -Performance curves of the integrated light-to-sensing system of the present invention under different μ; wherein, (a) data rate; (b) RMSE; (c) EH.

[0030] Fig.10 -The performance curves of the integrated system of light transmission and sensing energy of different LDs of the present invention; wherein, (a) red light LD; (b) green light LD; (c) blue light LD. DETAILED DESCRIPTION

[0031] The implementation mode and principle of the present invention are further described in detail below with reference to the accompanying drawings.

[0032] 1.O-ICSPT system framework

[0033] The optical communication, sensing and energy integration system framework proposed by the present invention is as follows: Figure 1(a) As shown, it includes a joint sensing and communication signal generating device for generating a joint sensing and communication digital signal. The output of the joint sensing and communication signal generating device is connected to a digital-to-analog converter to convert the joint sensing and communication digital signal into an analog electrical signal. The analog electrical signal output by the digital-to-analog converter is connected to a transmitter through a driving circuit, and the analog electrical signal is converted into an optical signal by the transmitter; the optical signal output by the transmitter generates two beams of light through a beam splitter; one beam of light is connected to an information decoding module and a sensing processing module; the other beam of light is connected to an energy harvesting module for energy harvesting. Direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) has advantages such as high spectral efficiency, resistance to multipath interference, flexible bandwidth allocation, and good time-domain autocorrelation, and is used as the ISAC waveform. A laser diode (LD) has advantages such as a large bandwidth, a small divergence angle, high collimation, and concentrated energy, and is very suitable for the O-ICSPT system and is used as the transmitter. The present invention generates an ISAC signal through an OFDM modulator as shown in Figure 1 (b). First, the binary bit sequence is subjected to quadrature amplitude modulation (QAM) mapping. Then, a training sequence is inserted for channel estimation. After applying Hermitian symmetry, an inverse fast Fourier transform (IFFT) is performed to obtain a real-valued time-domain signal, and finally, a cyclic prefix (CP) is inserted to obtain the joint sensing and communication digital signal to be transmitted. This digital signal is converted into an analog electrical signal through a digital-to-analog (D / A) converter. Let s represent the continuous data symbol. For a given peak amplitude A>0 of s, -A<s<A. The mean and variance of s are respectively (ε>0). After passing through the driving circuit, the transmitted signal is expressed as

[0034]

[0035] where g is defined as the gain of the power amplifier, and I DC is defined as the bias current. The LD uses intensity modulation and requires that the transmitted signal is non-negative, that is

[0036] The total transmitted electrical power of the system is expressed as

[0037]

[0038] The total transmitted optical power of the system is expressed as

[0039]

[0040] where ξ is defined as the optical power generated per unit current exciting the LD (W / A).

[0041] The analog electrical signal is converted into an optical signal by the transmitter after passing through the driving circuit. Flexible resource allocation is achieved by splitting the optical power in the spatial domain. The optical power splitting is realized through a beam splitter, and its model is as shown in Figure 1(d) As shown. The spectroscope can be integrated at the transmitting end or the receiving end, which means that the spectroscope can be placed at the position where the laser is emitted at the transmitting end, or at the position where the laser is incident at the receiving end, which is determined by the specific needs of different application scenarios. The light beam emitted by the LD is divided into two sub-beams according to a certain ratio by the spectroscope. One part of the light beam is emitted along the original path and is used for communication and perception. The other part of the light beam is turned 90 degrees and is used for EH. If the optical power division factor is set to μ, the optical power used for communication and perception is expressed as

[0042]

[0043] Optical power writing for EH

[0044]

[0045] Where μ∈[0,1]. The parameter μ determines the optical power resource allocation. By adjusting μ, a flexible performance trade-off can be achieved between the synaesthesia performance and the EH performance.

[0046] The receiving module of the O-ICSPT system of the present invention is divided into three parts: information decoding, perception processing and EH. Optical power division separates the functions of synaesthesia and EH, which means that different types of photoelectric converters can be used as receivers for signal detection and EH. PD has the advantages of high sensitivity, high response speed and low noise. The electric energy conversion of PV cells is higher than that of other photoelectric conversion devices. Therefore, PD1, PD2 and PV are used as photoelectric converters for communication, perception and EH of the present invention respectively to maximize their respective advantages. In the radio frequency synaesthesia energy integration system, the energy of electromagnetic waves can be collected by rectifying antennas. The present invention belongs to an optical communication system, and photovoltaic cells are the best energy harvesting devices known at present. In the embodiment, the perception application scenario of the present invention is ranging, and the O-ICSPT system of the present invention adopts a passive perception method based on reflected light for ranging. Compared with the diffuse reflection on the target side, the light reflector can greatly enhance the light reflectivity, thereby significantly improving the quality of the reflected light. In the embodiment, a corner cube reflector (CCR) is used as a light reflector. Lidar is a typical application of light perception, with functions such as target detection, ranging, angle measurement, and imaging.

[0047] The following is a detailed introduction to each receiving module of the O-ICSPT system.

[0048] (1) Information decoding module

[0049] The information decoding module includes a photodiode I (PD1), an analog-to-digital converter and an OFDM demodulation module. The light beam is converted into an analog electrical signal by the photoelectric converter, and the analog electrical signal is converted into a digital signal by the analog-to-digital converter. The digital signal enters the OFDM demodulation module and is restored to the original binary bit sequence after OFDM demodulation.

[0050] The line-of-sight (LOS) channel gain of the communication module is expressed as

[0051]

[0052] Where m = -ln2 / ln(cos(Φ 1 / 2 )) is the Lambertian radiation index, Φ 1 / 2 is the half power half angle of LD; d 1 Defined as the distance between LD and PD1; A c represents the detection area of ​​PD1; φ and are defined as the exit angle and the incident angle, respectively; in is the optical filter gain, is the optical lens gain, n and Ψ c are defined as the reflection coefficient and the half field of view (FOV) of the optical lens, respectively.

[0053] The communication receiving signal is expressed as

[0054]

[0055] where ρ c is the responsivity of PD1, which represents the current generated per watt of incident light power (A / W), n c The variance is defined as Zero-mean Gaussian noise.

[0056] OFDM demodulation is the inverse process of modulation, such as Figure 1 (c) is shown. In the OFDM demodulation module, the digital signal is synchronized and the cyclic prefix CP is removed, and then the frequency domain symbol is obtained through fast Fourier transform (FFT); the frequency domain symbol is compensated for channel distortion through channel estimation and equalization, and then orthogonal amplitude modulation QAM demapping is performed to restore the original binary bit sequence. The received signal-to-noise ratio (SNR) of the communication signal is calculated by the following formula

[0057]

[0058] Assuming that the modulation order of the transmitted symbol is M and the effective bandwidth of the system is B, the transmission data rate is expressed as B×log 2 (M).

[0059] (2) Perception Processing Module

[0060] The perception processing module of the present invention comprises a photodiode II and an analog-to-digital converter. The light beam reflected by the light reflector is converted into an analog electrical signal by PD2, and the analog electrical signal is converted into a digital signal by the analog-to-digital converter. The output of the synaesthesia signal generating device is connected to an upsampling module, and the upsampling module upsamples the time domain samples of the digital signal generated by the synaesthesia signal generating device at the same upsampling rate. The output of the upsampling module and the output of the analog-to-digital converter are respectively connected to a cross-correlation module. The cross-correlation module adopts a time domain cross-correlation method, and uses the digital signal generated by the synaesthesia signal generating device and the time domain samples of the digital signal converted by the analog-to-digital converter to perform distance measurement to realize perception capability.

[0061] Different from the communication channel model, the perception channel model must consider the effect of light reflection. CCR can gather and reflect light back to the location of the light source. Its model is as follows Figure 1 (e) D is the diameter of CCR. Assuming that the light beam used for sensing can always be fully reflected by CCR and LD is a point light source, the LOS channel gain of the sensing module is expressed as

[0062]

[0063] where d 2 Defined as the distance between CCR and PD2; A s represents the detection area of ​​PD2; r is the reflectivity of CCR; Ψ s and r denote the FOV half angles of PD2 at the sensing transmitter and CCR at the sensing receiver, respectively. The propagation distance of the sensing signal is twice the distance between the transmitter and the ranging target. Due to the influence of the reflected light on PD2, a cos(φ) term is added. In addition, the κ(·) term should be calculated based on φ.

[0064] The perceived received signal is expressed as

[0065]

[0066] where ρ s is the responsivity of PD1, n s The variance is defined as Zero-mean Gaussian noise.

[0067] The quality of reflected light is an important factor in determining the perception performance. The received SNR of the perception signal is calculated as

[0068]

[0069] The present invention adopts the time domain cross-correlation method to measure the distance using the time domain samples of the original OFDM signal and the reflected OFDM signal to meet the perception capability. Before performing the time domain cross-correlation, the time domain samples of the original OFDM signal should be upsampled at the same upsampling rate. Let α represent the upsampling rate, then the maximum likelihood estimate of the flight time is expressed as

[0070]

[0071] where x(n) and y s (n) are the upsampled time domain samples of the original OFDM signal and the time domain samples of the transmitted OFDM signal, respectively. w represents the length of the time domain window selected for cross-correlation before upsampling. The estimated distance is Where c is the speed of light. Then the root mean square error RMSE is expressed as Where N is the number of ranging times.

[0072] Let R s represents the sampling rate of the analog / digital (A / D) conversion of the sensing receiver, then the range resolution and the maximum ranging distance are Δd = c / (2R s ), d max =c(αL w -1) / (2R s ).

[0073] (3) EH module

[0074] PV cells are an important part of EH modules, and their output characteristics are closely related to light intensity. When the light intensity changes, the output current and voltage of the PV will change, which directly affects the output power of the cell, thereby changing its internal impedance. In order to maximize the output power of the PV, the system must operate at the maximum power point. Assuming that there is a constant luminous flux falling on the PV module and the PV operates at the maximum power point, an electrical equivalent analysis is performed. The equivalent circuit model of PV is as follows Figure 1 As shown in (f), the photocurrent source I ph 、Diode I 0 , parallel resistance R SH and series resistance R S Composition. ph represents the source current generated by the incident light. The diode is used to simulate direct current. The parallel resistance represents the reactive leakage current path, simulating impurities in the junction and defects in the crystal structure that make up the PV module. The parallel resistance is very large in practice and its effect can be considered negligible. The series resistance describes the losses caused by the resistance of the welded cell boundaries, interconnect components and semiconductors that make up the PV module. The current generated by the PV is expressed as

[0075]

[0076] Where a = kJT C / q e is the modified PV ideal factor. k represents the Boltzmann constant, J is the PV ideal factor, T C is the ambient temperature, q e is the charge of the electron. ph Depends on the light intensity received by the PV, calculated by the following formula

[0077] I ph =h e ρ e (1-μ)ξI DC , (14)

[0078] where ρ e is the responsiveness of the PV (A / W), h e Indicates channel gain

[0079]

[0080] where d 3 It is the sum of the distances between LD and the spectroscope and between the spectroscope and PV; Ae represents the detection area of ​​PV; Ψ e Defined as the FOV half angle of the PV.

[0081] Assuming the short-circuit current is ph Equal, ignoring the open circuit voltage V oc With R SH The ratio between them is V oc The saturation current of the diode can be derived from

[0082]

[0083] Using the fractional open circuit voltage method, the output voltage V o It can be approximated as V o =fV oc , f∈[0.71,0.78] is the filling factor of PV. The collected energy is expressed as

[0084] P=fIV oc (17)

[0085] Then the EH efficiency of PV is η=P / P EH × 100%. EH is the emitted light power used for energy harvesting.

[0086] 2. Experimental verification of O-ICSPT system

[0087] The present invention built an O-ICSPT system to conduct a conceptual experiment verification. The system device is as follows: Figure 2As shown. The OFDM signal generated offline is loaded into the arbitrary waveform generator (AWG: UNI-T UTG9604T) for D / A conversion and output driven by Vpp. The analog signal is amplified by the electrical amplifier (EA: Mini-Circuits ZHL-6A-S+) and coupled with DC through the DC bias Bisa-Tee (Mini-circuits ZFBT-4R2GWFT+). Subsequently, the LD (Red LD: UshioHL63603TG, 638nm; Green LD: Osram PLT3520D, 520nm; Blue LD: Osram PL450B, 450nm) is driven and the electrical signal is converted into an optical signal. The beam is divided into two sub-beams according to a certain ratio at the beam splitter (HYGX, HCBS1). After one of the sub-beams passes through the beam splitter, it is detected by the avalanche photodiode (APD: Hamamatsu C12702-11) at the receiving end and converted into an electrical signal. The electrical signal is sampled and recorded by an oscilloscope (OSC: Tektronix MDO3034) and forwarded for offline communication signal demodulation. The receiving end is also equipped with a CCR (Thorlabs PS976) to reflect the beam back to the transmitter. The reflected light is detected by the APD and then A / D converted by the OSC, and then the delay is calculated by cross-correlation to estimate the distance. After the other sub-beam turns 90 degrees, it is absorbed by a gallium arsenide GaAs PV and converted into electrical energy. The PV is connected to a load resistor, and the collected energy is measured using a digital power meter (Chroma 66205).

[0088] The specific experimental parameters are listed in Table I. The six low-frequency subcarriers are filled with zeros due to the poor response of EA. The effective bandwidth of the system is 200×122 / (256+8)≈92.42MHz. The range resolution is 3×10 8 / (2×2.5×10 9 )=0.06m.

[0089] Table 1 Experimental parameters

[0090]

[0091]

[0092] In order to clearly describe the performance of the proposed O-ICSPT system, the following example is given. Through a comprehensive experimental study, the system characteristics are revealed, and the influence of factors such as bias current, Vpp, and light source wavelength on each functional module is clarified.

[0093] 1. O-ICSPT system features

[0094] Figure 3 The voltage-current (VI) characteristic curves of LDs with three different wavelengths are shown (see Figure 3 a) and output power and current (PI) characteristic curve (see Figure 3 b). The characteristic curves of the three LDs all show obvious nonlinear characteristics. The threshold currents of the red, green, and blue LDs are 50mA, 30mA, and 20mA, respectively.

[0095] Figure 4 The amplitude spectrum and normalized channel frequency response of the received signal are shown. Figure 4 (a) is red light LD; Figure 4 (b) is green light LD; Figure 4 (c) is a blue light LD. As the frequency increases, the amplitude of the received signal gradually decays, which means that the SNR on different subcarriers decreases as the frequency increases. This is attributed to Figure 4 (d) shows the low-pass frequency response. The -10dB bandwidths of the red, green, and blue LDs are 57.6MHz, 46.2MHz, and 51.5MHz, respectively.

[0096] By changing the resistance of the load resistor, the VI curve of the PV under different bias currents is measured, such as Figure 5 As shown, Figure 5 (a) is red light LD; Figure 5 (b) is green light LD; Figure 5 (c) is a blue light LD. For any VI curve, there is a maximum power point, and its corresponding resistance is the best matching impedance under the light intensity. In all subsequent experiments involving EH, the best matching impedance was obtained by the above method, that is, the PV always works at the maximum power point. In addition, the output power of the PV is 0 when there is no directional light source, that is, the energy collected in the experiment comes from the LD light source.

[0097] 2.O-ICSPT system performance

[0098] Firstly, the effects of bias current, Vpp and light source wavelength on the performance of each functional module were studied. Figure 6 , Figure 7 , Figure 8 As shown in the figure. In order to fully explore the performance of the built O-ICSPT system, optical power resource allocation is not performed here. The performance indicators of communication, perception and EH functions are measured when all optical power resources are obtained. The modulation order of the transmitted signal is 32QAM.

[0099] Figure 6 The bit error rate (BER), RMSE and EH performance of the O-ICSPT system under different bias currents are demonstrated. Figure 6 (a)-(c) are the BER, RMSE and EH performance curves corresponding to the red light LD; Figure 6 (d)-(f) are the BER, RMSE and EH performance curves corresponding to the green light LD; Figure 6 (g)-(i) are the BER, RMSE and EH performance curves corresponding to the blue light LD. The BER performance takes into account the 7% forward error correction coding BER threshold, i.e., 3.8×10 -3 . Both BER and RMSE first decrease and then increase with the increase of bias current. For both communication and perception, there is an optimal bias current that optimizes the communication and perception performance. The value of the optimal bias current is affected by Vpp. The AC component carries the information of synaesthesia, which is manifested as periodic fluctuations in the intensity of the optical signal. If the bias current is too small, it will cause signal clipping. As the bias current gradually increases, the bias current gradually meets the requirement of non-negative transmission signal, and the LD works in the linear range. However, as the bias current continues to increase, the LD will enter the nonlinear working range, thereby deteriorating the waveform. EH continues to increase with the increase of bias current. The DC component provides stable optical power, is the main source of energy transmission, and has a direct impact on the output performance of PV. Therefore, the choice of bias current has an important impact on the performance of the O-ICSPT system. Different values ​​of bias current mean a performance compromise between synaesthesia and EH.

[0100] Figure 7 The BER, RMSE and EH performance of the O-ICSPT system under different Vpp are described. Figure 7 (a)-(c) are the BER, RMSE and EH performance curves corresponding to the red light LD; Figure 7 (d)-(f) are the BER, RMSE and EH performance curves corresponding to the green light LD; Figure 7(g)-(i) are the BER, RMSE and EH performance curves corresponding to the blue light LD. Both BER and RMSE performance first improve and then deteriorate with the increase of Vpp. For both communication and perception, there is an optimal Vpp, which makes the communication and perception performance optimal. The value of the optimal Vpp is affected by the bias current. The modulation depth of the LD describes the relationship between the AC signal and the bias current, which is defined as the ratio of the difference between the peak current and the bias current to the bias current. When the bias current is constant, Vpp determines the size of the modulation depth. If Vpp is too small, the optical power of the AC signal is insufficient, which will lead to insufficient received SNR. As Vpp gradually increases, the optical power of the AC signal gradually increases, and the received SNR also increases. However, excessive Vpp will cause the nonlinear distortion of the LD to increase, deteriorate the signal waveform, and cause the communication and perception performance to deteriorate. In addition, a larger Vpp will cause greater current fluctuations, which may increase the heat generated inside the LD. The increase in temperature will reduce the conversion efficiency of the LD, resulting in a decrease in the emitted optical power. Compared with the bias current, EH is very little affected by Vpp. When the bias current is small, the luminous intensity of the LD is low, and the total optical power received by the corresponding PV cell is also low. In this case, the AC signal increases the instantaneous maximum value of the light intensity, which may improve the energy collection performance of the PV. Under high bias current, the VI characteristics of the photovoltaic panel are close to the saturation region, and the light intensity fluctuation introduced by the AC signal may cause the conversion efficiency to decrease.

[0101] Figure 8 The performance profile of each functional module of the O-ICSPT system is described. As mentioned above, whether it is bias current or Vpp, excessive or too small values ​​will lead to deterioration of BER and RMSE performance. Too low bias current and Vpp will drown out the signal in the noise, resulting in a decrease in the received SNR. Too high bias current and Vpp will cause nonlinear effects. Therefore, for both communication and perception, an available dynamic range can be circled, and there is an optimal operating point. The optimal operating point of the system can be determined by traversing bias current and Vpp. The wavelength of the light source has relatively little effect on the communication and perception performance, which depends more on the received SNR. The bias current determines the light intensity of the LD. The larger its value, the greater the output power of the PV. The effect of Vpp on the EH is very weak and can be almost ignored. Therefore, there is no optimal operating point for the EH. The maximum energy that can be collected depends on the maximum bias current that the LD can withstand within the operating range. The wavelength of the light source significantly affects the performance of the EH because the responsiveness of the PV to light waves of different wavelengths is significantly different.

[0102] Then, the experiment demonstrated a communication-centric O-ICSPT system, such as Fig. 9 , Fig.10 As shown. Figure 8The optimal communication operating points of the three LD light sources were determined. The optimal bias of the red LD is 70mA, and the optimal drive Vpp is 100mV. The optimal bias of the green LD is 50mA, and the optimal drive Vpp is 150mV. The optimal bias and optimal drive Vpp of the blue LD are 50mA and 200mV, respectively. In the following experiments, when the value of the optical power division ratio factor μ is not 0, the O-ICSPT system operates at the optimal communication operating point. When the value of μ is 0, the Vpp operating point of the red LD, green LD, and blue LD is 0mV, and the bias current operating points are 160mA, 250mA, and 100mA, respectively. In addition, a bit loading strategy is adopted to alleviate the low-pass frequency response of the system to maximize the achievable data rate of the system.

[0103] Fig. 9 The performance of each functional module of the O-ICSPT system changes with μ, among which, Fig. 9 (a) is the data rate; Fig. 9 (b) is RMSE; Fig. 9 (c) is energy harvesting. When μ is 0, it means that all optical power is used for EH. At this time, the bias current is not constrained by the communication and perception functions, and can be taken as the maximum bias current that the LD can withstand to obtain the most EH. As μ increases, the data rate continues to increase, the ranging RMSE continues to decrease, and the collected energy continues to decrease. This is because, as μ increases, more optical power is used for communication and perception, and less optical power is used for EH. Optical power determines the received SNR and the output current of PV. When μ is 1, it means that all optical power is used for communication and perception. At this time, the communication data rate and ranging RMSE performance are optimal.

[0104] Fig.10 The performance of the O-ICSPT system with different LD light sources is described, among which, Fig.10 (a) is red light LD; Fig.10 (b) is green light LD; Fig.10 (c) is a blue light LD. By dividing the optical power in the spatial domain, a performance compromise between synaesthesia and EH is achieved. There is a constraint relationship between synaesthesia performance and EH performance. The experimental results show that when the light source is a red light LD with a wavelength of 638nm, the maximum data transmission rate of the O-ICSPT system is about 632.58Mbps, the minimum ranging RMSE is close to 0, and the maximum EH is about 10.02mW. Table 2 shows the EH efficiency of PV cells when LDs of different wavelengths are used as light sources when μ is 0. Compared with green and blue light, GaAs PV absorbs red light better and has higher conversion efficiency.

[0105] Table 2 Energy collection efficiency of different LDs

[0106]

[0107] Finally, it should be noted that the above examples of the present invention are merely examples for illustrating the present invention, and are not intended to limit the embodiments of the present invention. Although the applicant has described the present invention in detail with reference to the preferred embodiments, for those of ordinary skill in the art, other different forms of changes and modifications can be made based on the above description. It is impossible to list all the embodiments here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. An optical-synaesthesia-energy integrated system, comprising a synaesthesia signal generating device for generating a synaesthesia-integrated digital signal, characterized in that: The output of the synaesthesia signal generating device is connected to a digital-to-analog converter to convert the synaesthesia integrated digital signal into an analog electrical signal. The analog electrical signal output by the digital-to-analog converter is connected to a transmitter through a driving circuit, and the analog electrical signal is converted into an optical signal through the transmitter; the optical signal output by the transmitter generates two light beams through a spectroscope; one light beam is connected to an information decoding module and a perception processing module; and the other light beam is connected to an energy collection module for energy collection.

2. The light-transmitting sensory energy integrated 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. The light beam is converted into an analog electrical signal through a photoelectric converter, and the analog electrical signal is converted into a digital signal through an analog-to-digital converter. The digital signal enters the OFDM demodulation module; in the OFDM demodulation module, the digital signal is synchronized and the cyclic prefix is ​​removed, and then the frequency domain symbol is obtained through fast Fourier transform; the frequency domain symbol is compensated for channel distortion through channel estimation and equalization, and then orthogonal amplitude modulation demodulation is performed, that is, the original binary bit sequence is restored.

3. The light-transmitting, sensing-energy integrated system according to claim 1, characterized in that: The light beam is connected to a sensing processing module through a light reflector; the sensing processing module includes a photodiode II and an analog-to-digital converter, the light beam reflected by the light reflector is converted into an analog electrical signal through the photoelectric converter, and the analog electrical signal is converted into a digital signal through the analog-to-digital converter; the output of the synaesthesia signal generating device is connected to an upsampling module, the upsampling module upsamples the time domain samples of the digital signal generated by the synaesthesia signal generating device at the same upsampling rate, the output of the upsampling module and the output of the analog-to-digital converter are respectively connected to a cross-correlation module, the cross-correlation module adopts a time domain cross-correlation method, and uses the digital signal generated by the synaesthesia signal generating device and the time domain samples of the digital signal converted by the analog-to-digital converter to perform distance measurement to achieve sensing capability.

4. The light-transmitting, sensing-energy integrated system according to claim 1, characterized in that: The energy collection module is a photoelectric converter; the photoelectric converter is a photovoltaic cell.

5. The light-transmitting sensory energy integrated system according to claim 1, characterized in that: The process of the synaesthesia signal generating device generating the synaesthesia integrated digital signal is as follows: firstly, the original binary bit sequence is subjected to orthogonal amplitude modulation mapping, and then a training sequence is inserted for channel estimation; then, an inverse fast Fourier transform is performed after applying Hermitian symmetry to obtain a real-valued time domain signal; and the synaesthesia integrated digital signal is obtained after a cyclic prefix is ​​inserted into the time domain signal.

6. The light-transmitting, sensing-energy integrated system according to claim 1, characterized in that: The beam splitter is integrated on the transmitter or on the receiver.

7. The light-transmitting, sensing-energy integrated system according to claim 3, characterized in that: The transmitter is a laser diode; the light reflector is a corner cube reflector.

8. The light-transmitting, sensing-energy integrated system according to claim 7, characterized in that: When the light source generated by the laser diode is red light with a wavelength of 638 nm, the maximum data transmission rate, the minimum ranging root mean square error and the maximum energy collection can be achieved.

9. The light-transmitting, sensing-energy integrated system according to claim 7, characterized in that: The laser diode is a red laser diode, the optimal bias current of the red laser diode is 70 mA, and the optimal driving Vpp is 100 mV; or the laser diode is a green laser diode, the optimal bias current of the green laser diode is 50 mA, and the optimal driving Vpp is 150 mV; or the laser diode is a blue laser diode, the optimal bias current of the blue laser diode is 50 mA, and the optimal driving Vpp is 200 mV.

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