A chirped spread spectrum photonic terahertz communication and sensing integrated system

Abstract

This invention discloses a chirped spread spectrum photonic terahertz communication and sensing integrated system, comprising: a coherent light source module for generating two coherent single-frequency optical carrier signals; a signal modulation module for generating a baseband chirped spread spectrum communication and sensing integrated signal and modulating it onto one beam to form a carrier signal; an integrated signal transmission module for using another single-frequency optical carrier signal as an optical local oscillator signal, coupling it with the carrier signal, and generating and radiating the terahertz communication and sensing integrated signal through optical down-conversion; a communication receiving module for frequency conversion and demodulation of the received terahertz communication and sensing integrated signal to recover the communication information in the signal; and a radar receiving module for dechirping and target information estimation of the received terahertz communication and sensing integrated signal. This system fully leverages the advantages of the photonic terahertz architecture to generate an ultra-wideband chirped spread spectrum integrated signal, thereby achieving a communication and sensing integrated system with high spread spectrum gain and high energy efficiency.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to a chirped spread spectrum photonic terahertz communication and sensing integrated system. Background Technology

[0002] The rapid development of mobile communications has led to increasingly complex electromagnetic environments, exacerbating the demand for reliable connections in wireless networks and driving growing attention to integrated communication and sensing technologies. This innovative technology can effectively improve spectral efficiency, energy efficiency, hardware utilization, and the performance of signal processing modules. However, it still cannot overcome the limitations of available bandwidth resources or solve the problem of spectrum scarcity in current operating frequency bands. Meanwhile, achieving ultra-high-speed communication and high-precision sensing remains a key application scenario for integrated systems. These challenges highlight the necessity of exploring higher, less congested spectrum resources, such as the terahertz band.

[0003] To deploy an integrated terahertz communication and sensing system, a dedicated integrated sensing waveform needs to be designed to further improve resource utilization efficiency. Currently, mainstream solutions include multi-carrier waveforms, represented by orthogonal frequency division multiplexing (OFDM) waveforms, and single-carrier waveforms, represented by chirped modulation. Among these, spread-spectrum-based single-carrier waveforms have attracted researchers' attention by sacrificing signal bandwidth in exchange for the signal-to-noise ratio gain of spread-spectrum processing. More importantly, while terahertz systems possess large signal bandwidth, they face the problem of limited RF front-end power, which greatly restricts the deployment of integrated terahertz systems in complex scenarios such as multi-target and long-distance operations. Therefore, an integrated signal based on spread-spectrum signals is of great significance for high-energy-efficiency integrated terahertz sensing systems.

[0004] In 2022, Wenlin Bai et al. from Southwest Jiaotong University published an article entitled "Photonic millimeter-wave joint radar communication system using spectrum-spreading phase-coding" in the journal IEEE Transactions on Microwave Theory and Techniques. This paper uses direct-sequence spread spectrum signals as the integrated communication and sensing waveform, employing WH-sequence spreading and M-sequence scrambling to generate the integrated waveform. Based on a photonic system, it achieved wireless communication at a rate of 1 Gbit / s and a sensing range resolution of 3.5 cm in the 35 GHz band, along with a 13.8 dB spread spectrum communication performance gain, verifying the effectiveness of the direct-sequence spread spectrum integrated system.

[0005] In 2024, Abdulrahman K. Alzamil et al. from King Saud University published an article in the journal Photonics entitled "Development of an integrated communication and sensing system using spread spectrum and photonics technologies." This paper uses pseudo-random PN codes as the spreading sequence and achieves a wireless communication rate of 50 Mbit / s and a radar sensing resolution of 43 cm in the 28 GHz band based on a photonics system. The system also achieved the expected experimental results with 50 km fiber optic transmission, demonstrating the superiority of integrated spread spectrum signals.

[0006] The performance of direct sequence spread spectrum (DSS) systems heavily relies on the spreading sequence. Achieving higher resolution requires longer code lengths, which limits communication rates. Furthermore, the waveform must be processed by a digital receiver at the radar receiver, increasing system complexity and reducing real-time performance. Additionally, the low carrier frequency limits system bandwidth, failing to fully leverage the advantages of integrated spread spectrum signals. Therefore, exploring high-frequency, high-speed integrated spread spectrum signals and systems has significant research value and strategic importance. Summary of the Invention

[0007] In view of the above, the purpose of this invention is to provide a chirped spread spectrum photonic terahertz communication and sensing integrated system. This system fully leverages the advantages of the photonic terahertz architecture to generate an ultra-wideband chirped spread spectrum integrated signal, thereby achieving a communication and sensing integrated system with high spread spectrum gain and high energy efficiency.

[0008] To achieve the above-mentioned objectives, the embodiments provide a chirped spread spectrum photonic terahertz communication and sensing integrated system, including a coherent light source module, a signal modulation module, an integrated signal transmitting module, a communication receiving module, and a radar receiving module; The coherent light source module is used to generate two coherent single-frequency optical carrier signals; The signal modulation module is used to generate a baseband chirped spread spectrum communication sensing integrated signal and modulate it onto a beam to form a carrier signal; The integrated signal transmitting module is used to use another single-frequency optical carrier signal as an optical local oscillator signal, and after coupling it with the carrier signal, it generates and radiates the integrated terahertz communication and sensing signal through optical down-conversion. The communication receiving module is used to perform frequency conversion and demodulation on the received terahertz communication sensing integrated signal to recover the communication information in the signal; The radar receiving module is used to perform dechirping and target information estimation on the radar echo signal corresponding to the received terahertz communication and sensing integrated signal.

[0009] Preferably, the coherent light source module filters out two single-frequency optical carrier signals in the optical frequency comb with a frequency interval equal to the terahertz center wavelength through an optical filter; Among them, optical frequency combs include optical frequency combs based on electro-optic modulation, resonant cavities, or mode-locked lasers; Optical filters include passive optical filters or active optical filters.

[0010] Preferably, the coherent light source module is an electro-optic modulated coherent light source module, which includes a tunable laser, a polarization controller 2, a phase modulator, a signal generator, an electrical amplifier 1, and an optical filter; The tunable laser is used to generate a seed laser, and the tunable laser includes a fiber laser, a semiconductor laser, or a microcavity laser. The polarization controller 2 is used to adjust the polarization state of the seed laser to optimize the output power of the phase modulator; The signal generator is used to generate a single-frequency radio frequency signal; The electrical amplifier 1 is used to increase the power of a single-frequency radio frequency signal; The phase modulator is driven by a single-frequency radio frequency signal and generates a series of optical sidebands centered on the seed laser wavelength; The optical filter is used to filter out two coherent single-frequency optical carrier signals from the output optical signal of the phase modulator. The center frequency difference of the single-frequency optical carrier signals corresponds to the center frequency of the generated terahertz signal.

[0011] Preferably, the signal modulation module includes an optical amplifier 1, a signal generator 1, and an optical modulator 1; The optical amplifier 1 is used to increase the power of a single-frequency optical carrier signal to drive the optical modulator 1, wherein the optical amplifier 1 includes a semiconductor amplifier or an erbium-doped fiber amplifier. The signal generator 1 is used to generate a baseband chirped spread spectrum communication sensing integrated signal; The optical modulator 1 is used to modulate the baseband chirped spread spectrum communication sensing integrated signal onto the power-up single-frequency optical carrier signal to form a carrier signal. The optical modulator 1 includes a Mach-Zehnder modulator or a dual parallel Mach-Zehnder modulator.

[0012] Preferably, the integrated signal transmitting module includes an optical attenuator, an optical coupler, an optical amplifier 2, a polarization controller 1, and a terahertz signal transmitter connected in sequence. The optical attenuator is used to adjust the power of another single-frequency optical carrier signal, which serves as the local oscillator signal, to match the power of the modulated carrier signal. The optical coupler is used to couple the local oscillator optical signal and the carrier signal; The optical amplifier 2 is used to amplify the signal coupled by the optical coupler, wherein the optical amplifier 2 includes a semiconductor amplifier or an erbium-doped fiber amplifier; The polarization controller 1 is used to adjust the polarization state of the coupled light output by the optical amplifier 2 so as to match the optical axis of the terahertz signal transmitter. The terahertz signal transmitter is used to generate an integrated terahertz communication and sensing signal based on the optical signal output by the polarization controller 1 through optical heterodyne. The terahertz signal transmitter includes a single-row carrier photodetector or a photoconductive antenna.

[0013] Preferably, the communication receiving module includes a terahertz signal receiver and a communication demodulation module connected in sequence; The terahertz signal receiver is used to receive radiated terahertz communication and sensing integrated signals and down-convert them to intermediate frequency or baseband. The terahertz signal receiver includes a Schottky barrier diode, a subharmonic mixer, and a photoconductive antenna. The communication demodulation module is used to perform clock synchronization, despreading, signal equalization, frequency offset estimation, and phase noise compensation on the down-converted signal, and finally demodulates and recovers the communication information.

[0014] Preferably, the radar receiving module includes a terahertz signal receiver and a radar processing module; The terahertz signal receiver is used to receive the radar echo signal corresponding to the radiated terahertz communication and sensing integrated signal, and down-convert it to an intermediate frequency. The terahertz signal receiver includes a Schottky barrier diode, a subharmonic mixer, and a photoconductive antenna. The radar processing module is used to dechirp the down-converted radar echo signal through an optical or electrical scheme, and then extract target information from the dechirped signal.

[0015] Preferably, when the radar processing module achieves dechirping through an optical scheme, the radar processing module includes an electrical amplifier 2, an optical modulator 2, a photodetector, and a signal processing module connected in sequence. The electrical amplifier 2 is used to compensate for the power loss of the received radar echo; The optical modulator 2 is used to modulate the signal output by the electrical amplifier 2 onto the reference signal output by the optical modulator 1, wherein the optical modulator 2 includes a phase modulator or an intensity modulator. The photodetector beats the signal output from the amplifier 2 and the reference signal. The signal processing module estimates the target distance, speed, and position information based on the beat frequency signal.

[0016] Compared with the prior art, the beneficial effects of the present invention include at least the following: (1) The present invention designs a chirped spread spectrum integrated photonic terahertz communication and sensing system based on the photonic terahertz system architecture, which can generate ultra-wideband chirped spread spectrum integrated communication and sensing signals through optical external modulation, and realize high spread spectrum gain and high energy efficiency signal processing; (2) The present invention combines a highly stable coherent light source and an optical dechirping scheme to improve the quality of the integrated chirped spread spectrum communication and sensing signal and reduce the bandwidth requirements for processing the radar echo signal corresponding to the integrated chirped spread spectrum communication and sensing signal in the integrated system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 2 This is a schematic diagram of the integrated photonic terahertz communication and sensing system provided in the embodiment. Figure 1 This is a waveform diagram of the integrated chirped spread spectrum communication and sensing signal provided in the embodiment; Figure 3 This is a schematic diagram of the structure of a coherent light source module provided in the embodiment; Figure 4 This is a schematic diagram of the structure of a radar processing module provided in an embodiment. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of this invention.

[0020] The inventive concept of this invention is as follows: Addressing the problems of existing spread spectrum communication-sensing integrated systems, such as performance dependence on the spread spectrum sequence, limited communication rate, high radar system complexity, and limited bandwidth, this invention provides a chirped spread spectrum photonic terahertz communication-sensing integrated system. This system fully leverages the advantages of the photonic terahertz architecture to generate an ultra-wideband chirped spread spectrum integrated signal. Using the chirped signal as the spread spectrum basis provides superior communication performance, and hardware de-chirping simplifies the radar system architecture, reduces bandwidth requirements, and combined with the advantages of the terahertz band, ultimately achieves a communication-sensing integrated system with high spread spectrum gain and high energy efficiency.

[0021] Based on the above inventive concept, such as Figure 1 The diagram shown is a schematic of the integrated chirped spread spectrum communication and sensing system provided in the embodiment, including a coherent light source module, an integrated signal transmission module, a signal modulation module, a communication receiving module, and a radar receiving module.

[0022] In this embodiment, the coherent light source module is used to generate two coherent single-frequency optical carrier signals for the generation and reception of integrated terahertz communication and sensing signals. Specifically, as... Figure 3 As shown, an optical frequency comb is generated through electro-optic modulation, and then an optical filter is used to filter out two single-frequency optical carrier signals with a frequency interval equal to the center wavelength of the terahertz signal. The coherent light source module can be an electro-optic modulated coherent light source module, which includes a tunable laser, a polarization controller 2, a phase modulator, a signal generator, an electrical amplifier 1, and an optical filter. The tunable laser includes a fiber laser, a semiconductor laser, or a microcavity laser, used to generate a seed laser; the polarization controller 2 is used to adjust the polarization state of the seed laser to optimize the output power of the phase modulator; the signal generator is used to generate a single-frequency radio frequency signal; the electrical amplifier 1 is used to boost the power of the single-frequency radio frequency signal; the phase modulator is driven by the single-frequency radio frequency signal and generates a series of optical sidebands centered on the seed laser wavelength; the optical filter is used to filter out two coherent single-frequency optical carrier signals from the output optical signal of the phase modulator. The center frequency difference of the single-frequency optical carrier signals corresponds to the center frequency of the generated terahertz signal. The optical filter includes a passive optical filter and an active optical filter.

[0023] In this embodiment, the signal modulation module is used to modulate the generated baseband chirped spread spectrum communication sensing integrated signal onto a single-frequency optical carrier signal to form a carrier signal. Specifically, the signal modulation module includes an optical amplifier 1, a signal generator, and an optical modulator 1. The optical amplifier 1 is used to boost the power of the single-frequency optical carrier signal to drive the optical modulator 1. The optical amplifier 1 can be a semiconductor amplifier or an erbium-doped fiber amplifier. The signal generator generates the baseband chirped spread spectrum communication sensing integrated signal. The optical modulator 1 modulates the baseband chirped spread spectrum communication sensing integrated signal onto the boosted single-frequency optical carrier signal to form the carrier signal. The optical modulator 1 can be a Mach-Zehnder modulator or a dual-parallel Mach-Zehnder modulator.

[0024] In this embodiment, the integrated signal transmission module is used to couple another single-frequency optical carrier signal as an optical local oscillator signal with the carrier signal, and then generate and radiate a terahertz communication and sensing integrated signal through optical down-conversion. Specifically, the integrated signal transmission module includes an optical attenuator, an optical coupler, an optical amplifier 2, a polarization controller 1, and a terahertz signal transmitter connected in sequence. The optical attenuator is used to adjust the power of the other single-frequency optical carrier signal (which serves as the local oscillator signal) to match the power of the modulated carrier signal; the optical coupler is used to couple the local oscillator signal and the carrier signal; the optical amplifier 2 is used to amplify the coupled signal, wherein the optical amplifier 2 is a semiconductor amplifier or an erbium-doped fiber amplifier; the polarization controller 1 is used to adjust the polarization state of the coupled light to match the optical axis of the terahertz signal transmitter; the terahertz signal transmitter is used to generate the terahertz communication and sensing integrated signal based on the optical signal output by the polarization controller 1 through optical heterodyne, wherein the terahertz signal transmitter is a single-row carrier photodetector or a photoconductive antenna.

[0025] Specifically, such as Figure 2 As shown, in the generated chirped spread spectrum integrated communication and sensing signal, i.e. terahertz integrated communication and sensing signal, the communication symbols are spread using a chirped signal with a duration of Ts and a bandwidth of B.

[0026] In this embodiment, the communication receiving module is used to perform frequency conversion and demodulation on the received terahertz communication-sensing integrated signal to recover the communication information in the signal. Specifically, the communication receiving module includes a terahertz signal receiver and a communication demodulation module connected in sequence. Specifically, the terahertz signal receiver uses a Schottky barrier diode, a sub-harmonic mixer, and a photoconductive antenna to receive the radiated terahertz communication-sensing integrated signal and down-convert it to intermediate frequency or baseband; the signal processing module performs Gardner-based clock synchronization, despreading, blind equalization based on constant mode equalization algorithm, M-power power frequency offset estimation, and Viterbi phase noise compensation algorithm on the down-converted signal, and finally demodulates and recovers the communication information.

[0027] In this embodiment, the radar receiving module is used to perform dechirping and target information estimation on the radar echo signal corresponding to the terahertz communication and sensing integrated signal. Specifically, it includes a terahertz signal receiver and a radar processing module. Specifically, the terahertz signal receiver is used to receive the radar echo signal corresponding to the radiated terahertz communication and sensing integrated signal and down-convert it to an intermediate frequency. The radar receiving module includes a Schottky barrier diode, a subharmonic mixer, and a photoconductive antenna. The radar processing module is used to dechirp the down-converted radar echo signal using an optical scheme and then extract target information from the dechirped signal.

[0028] Specifically, such as Figure 4 As shown, a radar processing module based on optical dechirping includes an electrical amplifier 2, an optical modulator 2, a photodetector 2, and a signal processing module connected in sequence. The electrical amplifier 2 compensates for power loss in the radar echo signal; the optical modulator 2 uses a phase modulator or intensity modulator to modulate the radar echo onto a reference signal output from the optical modulator 1; the photodetector beats the radar echo signal and the reference signal; and the signal processing module estimates the target range, velocity, and position information based on the beat frequency signal.

[0029] The chirped spread spectrum photonic terahertz communication and sensing integrated system provided in the above embodiments can generate ultra-wideband chirped spread spectrum integrated signals and realize a communication and sensing integrated system with high spread spectrum gain and high energy efficiency.

[0030] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A chirped spread spectrum photonic terahertz communication and sensing integrated system, characterized in that, Includes a coherent light source module, a signal modulation module, an integrated signal transmitting module, a communication receiving module, and a radar receiving module; The coherent light source module is used to generate two coherent single-frequency optical carrier signals; The signal modulation module is used to generate a baseband chirped spread spectrum communication sensing integrated signal and modulate it onto a single-frequency optical carrier signal to form a carrier signal; The integrated signal transmitting module is used to use another single-frequency optical carrier signal as an optical local oscillator signal, and after coupling it with the carrier signal, it generates and radiates the integrated terahertz communication and sensing signal through optical down-conversion. The communication receiving module is used to perform frequency conversion and demodulation on the received terahertz communication sensing integrated signal to recover the communication information in the signal; The radar receiving module is used to receive the radar echo signal corresponding to the terahertz communication and sensing integrated signal for dechirping and target information estimation.

2. The integrated photonic terahertz communication and sensing system with chirped spread spectrum according to claim 1, characterized in that, The coherent light source module filters out two single-frequency optical carrier signals in the optical frequency comb with a frequency interval equal to the center wavelength of the terahertz through an optical filter. Among them, optical frequency combs include optical frequency combs based on electro-optic modulation, resonant cavities, or mode-locked lasers; Optical filters include passive optical filters or active optical filters.

3. The integrated photonic terahertz communication and sensing system with chirped spread spectrum according to claim 1, characterized in that, The coherent light source module is an electro-optic modulated coherent light source module, which includes a tunable laser, a polarization controller 2, a phase modulator, a signal generator, an electrical amplifier 1, and an optical filter. The tunable laser is used to generate a seed laser, and the tunable laser includes a fiber laser, a semiconductor laser, or a microcavity laser. The polarization controller 2 is used to adjust the polarization state of the seed laser to optimize the output power of the phase modulator; The signal generator is used to generate a single-frequency radio frequency signal; The electrical amplifier 1 is used to increase the power of a single-frequency radio frequency signal; The phase modulator is driven by a single-frequency radio frequency signal and generates a series of optical sidebands centered on the seed laser wavelength; The optical filter is used to filter out two coherent single-frequency optical carrier signals from the output optical signal of the phase modulator. The center frequency difference of the single-frequency optical carrier signals corresponds to the center frequency of the generated terahertz signal.

4. The integrated photonic terahertz communication and sensing system with chirped spread spectrum according to claim 1, characterized in that, The signal modulation module includes an optical amplifier 1, a signal generator 1, and an optical modulator 1; The optical amplifier 1 is used to increase the power of a single-frequency optical carrier signal to drive the optical modulator 1, wherein the optical amplifier 1 includes a semiconductor amplifier or an erbium-doped fiber amplifier. The signal generator 1 is used to generate a baseband chirped spread spectrum communication sensing integrated signal; The optical modulator 1 is used to modulate the baseband chirped spread spectrum communication sensing integrated signal onto the power-up single-frequency optical carrier signal to form a carrier signal. The optical modulator 1 includes a Mach-Zehnder modulator or a dual parallel Mach-Zehnder modulator.

5. The integrated photonic terahertz communication and sensing system with chirped spread spectrum according to claim 1, characterized in that, The integrated signal transmission module includes an optical attenuator, an optical coupler, an optical amplifier 2, a polarization controller 1, and a terahertz signal transmitter connected in sequence. The optical attenuator is used to adjust the power of another single-frequency optical carrier signal, which serves as the local oscillator signal, to match the power of the modulated carrier signal. The optical coupler is used to couple the local oscillator optical signal and the carrier signal; The optical amplifier 2 is used to amplify the signal coupled by the optical coupler, wherein the optical amplifier 2 includes a semiconductor amplifier or an erbium-doped fiber amplifier; The polarization controller 1 is used to adjust the polarization state of the coupled light output by the optical amplifier 2 so as to match the optical axis of the terahertz signal transmitter. The terahertz signal transmitter is used to generate an integrated terahertz communication and sensing signal based on the optical signal output by the polarization controller 1 through optical heterodyne. The terahertz signal transmitter includes a single-row carrier photodetector or a photoconductive antenna.

6. The integrated photonic terahertz communication and sensing system with chirped spread spectrum according to claim 1, characterized in that, The communication receiving module includes a terahertz signal receiver and a communication demodulation module connected in sequence. The terahertz signal receiver is used to receive radiated terahertz communication and sensing integrated signals and down-convert them to intermediate frequency or baseband. The terahertz signal receiver includes a Schottky barrier diode, a subharmonic mixer, and a photoconductive antenna. The communication demodulation module is used to perform clock synchronization, despreading, signal equalization, frequency offset estimation, and phase noise compensation on the down-converted signal, and finally demodulates and recovers the communication information.

7. The integrated photonic terahertz communication and sensing system with chirped spread spectrum according to claim 1, characterized in that, The radar receiving module includes a terahertz signal receiver and a radar processing module; The terahertz signal receiver is used to receive the radar echo signal corresponding to the radiated terahertz communication and sensing integrated signal, and down-convert it to an intermediate frequency. The terahertz signal receiver includes a Schottky barrier diode, a subharmonic mixer, and a photoconductive antenna. The radar processing module is used to dechirp the down-converted radar echo signal through an optical or electrical scheme, and then extract target information from the dechirped signal.

8. The integrated photonic terahertz communication and sensing system according to claim 7, characterized in that, When the radar processing module achieves dechirping through an optical scheme, the radar processing module includes an electrical amplifier 2, an optical modulator 2, a photodetector, and a signal processing module connected in sequence. The electrical amplifier 2 is used to compensate for the power loss of the received radar echo signal; The optical modulator 2 is used to modulate the signal output by the electrical amplifier 2 onto the reference signal output by the optical modulator 1, wherein the optical modulator 2 includes a phase modulator or an intensity modulator. The photodetector beats the signal output from the amplifier 2 and the reference signal. The signal processing module estimates the target distance, speed, and position information based on the beat frequency signal.

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