A low bit error rate antenna based on time reversal

Abstract

The application discloses a low bit error rate antenna based on time reversal, and belongs to the technical field of microwave antennas. In view of the technical pain point that the existing time reversal technology seriously depends on an external multipath environment and the system hardware cost is high, the application designs a kind of center coaxial feed monopole and peripheral high-order mode evanescent wave auxiliary structure. The high-order mode evanescent wave auxiliary structure efficiently extracts the near-field non-radiation evanescent wave and converts it into a propagating wave, actively constructs a high degree of freedom deterministic "pre-scattering" environment at the transmitting end, and completely decouples the dependence on the external random multipath channel from the physical bottom layer. The antenna works in the 2.2GHz-2.6GHz frequency band. Experiments show that, compared with a traditional monopole antenna, the application can significantly reduce the transmission bit error rate by about 30% in a non-line-of-sight rich multipath fading scene. The scheme completely avoids complex feed networks and expensive active T / R components, greatly improves the environmental robustness of the system with extremely low hardware overhead, and provides an innovative physical layer anti-fading new paradigm for high-reliability communication in a complex electromagnetic environment.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology, specifically relating to a low bit error rate antenna based on time inversion. Background Technology

[0002] In increasingly complex electromagnetic environments, wireless signal transmission faces unprecedented challenges. On the one hand, shadow fading caused by physical obstacles such as urban canyons and indoor partitions, as well as severe multipath effects caused by reflections from dense metal surfaces and building surfaces, collectively result in deep signal fading and delay spread, leading to persistently high bit error rates and severely restricting the high reliability and high speed requirements of communication systems. However, traditional methods for improving the static transmission environment (such as increasing base station deployment density or increasing transmission power) lead to exponentially increasing hardware energy consumption and spectrum interference costs. Energy consumption and base station construction expenditures account for a large portion of the total network operation cost. Furthermore, simply relying on increasing antenna size or complex equalization algorithms faces bottlenecks such as exploding computational complexity and real-time processing challenges. Therefore, researching new communication technologies that can actively improve wireless channels while balancing low energy consumption and high gain is particularly important.

[0003] Chinese patent application No. 201610723049.9 discloses a simultaneous full-duplex electromagnetic communication method based on time-reversal technology. This method involves deploying time-reversal mirror arrays at both the transmitting and receiving ends, constructing a time-reversal precoded signal using the round-trip propagation response of electromagnetic waves in complex channels, and achieving spatiotemporal focusing and adaptive matching compensation of the transmitted and received signals, thereby realizing full-duplex communication at the same frequency. In this method, the system measures and reverses the channel impulse response, then uses the time-reversed signal as a pre-weighted transmit waveform, enhancing the useful signal at the target receiver and suppressing multipath and self-interference, thus significantly improving spectrum utilization and communication quality. However, this scheme relies on relatively accurate and dynamically updated channel measurement and time-reversal processing, resulting in high system complexity and high requirements for hardware synchronization accuracy and computational power. In fast-changing channels and large-scale multi-user scenarios, the time-reversal focusing performance degrades, affecting system stability and the actual usable communication gain.

[0004] Chinese patent application No. 201610137833.1 discloses a two-dimensional spatial position modulation (2D-SPM) digital wireless communication method based on time-reversed electromagnetic wave dot array focusing. By constructing a multi-antenna dot array and introducing time-reversed electromagnetic wave focusing technology, different symbol mappings correspond to different two-dimensional spatial positions at the receiver, achieving a modulation method that utilizes the spatial dimension to carry information. This method first acquires the channel response under multipath conditions at the transmitting end and performs time reversal. Utilizing the characteristic that the time-reversed wave generates high-intensity focusing at a specific location and has weaker field strength at other locations, the signal energy is concentrated at the desired receiving location, thereby enhancing the useful signal, suppressing multipath interference and crosstalk, and improving the spectral efficiency and bit error rate performance of the communication system. However, this scheme, which relies on spatial dot arrays and time-reversed focusing, is quite sensitive to array layout, environmental stability, and channel measurement accuracy. It requires precise array calibration and complex transmit waveform design. When the environment changes significantly or the user's location changes rapidly, the dot array focusing effect will decrease significantly, leading to complex system implementation and certain limitations on robustness for engineering applications.

[0005] Patent document US12416703(B2) discloses a radio frequency (RF) sensing scheme based on time reversal technology, aiming to solve the problem of degraded object detection and tracking performance caused by multipath propagation in 5G and future communication systems. This scheme transmits an RF sensing signal and receives its echo, reversing the received waveform in the time domain, or generating a time-reversed signal using precoding techniques based on channel impulse response. By normalizing the energy of the reversed echo (e.g., power amplification) and retransmitting it, multipath channel compression is achieved within the frequency band, significantly improving the signal-to-noise ratio of target detection, thereby eliminating false targets and signal energy dispersion caused by multipath effects in complex environments (such as urban canyons or indoor partitions). However, this method still faces challenges in practical applications: direct time reversal or precoding processing under high bandwidth requires extremely high analog-to-digital / digital-to-analog conversion rates and memory computing capabilities, leading to a significant increase in system implementation complexity. Furthermore, this technology is highly dependent on the reciprocity and coherence of the channel. The time interval between the sensing signal and the time-reversal signal must be strictly limited (e.g., less than 200ms), otherwise dynamic changes in the environment will seriously affect the sensing accuracy and system stability.

[0006] Chinese patent application No. 200980121543.6 discloses a method, apparatus, and device for improving signal quality. This method is aimed at optimizing signal quality in optical communication systems. By statistically analyzing the error correction bit rate of each virtual channel during the forward error correction decoding process and further calculating the pre-correction bit error rate of the corresponding physical channel, the bit error rate is fed back to the optical module to adjust the receiving parameters, thereby improving the signal quality of the communication link, reducing the bit error rate during transmission, and enhancing system stability. Although this method can achieve adaptive link optimization by using bit error rate feedback, its effectiveness depends on the accuracy of error correction statistics and parameter feedback. In cases of multi-channel parallel transmission, large channel fluctuations, or insufficient closed-loop control, the optimization effect and real-time performance may be affected to some extent.

[0007] Chinese patent application No. 202010844673.0 discloses a method to improve the reliability of device communication. By sampling the header code of data frames and extracting clock information, and then dynamically replacing the preset sampling timing based on the extraction results, the accuracy of data frame synchronization and sampling at the receiving end is improved, and bit errors and frame errors caused by timing offset and synchronization errors are reduced, thereby improving the communication quality and transmission reliability between devices. However, although this method can effectively improve communication synchronization performance and reduce bit errors, its implementation still depends on the design of the header code, the stability of clock extraction, and the timeliness of sampling timing updates. In scenarios with poor signal quality or significant clock drift, the reliability improvement effect may be limited.

[0008] In summary, existing technical solutions for reducing the bit error rate in communication transmission have the following technical problems:

[0009] Currently, methods for reducing the bit error rate (BER) in communication transmission mainly rely on algorithm optimization, and there is a lack of mature solutions for directly reducing the BER in hardware. In research related to improving communication transmission quality through time reversal, existing work largely focuses on signal processing and transmission optimization, and similarly, no hardware-based method for reducing the BER has yet been developed. Summary of the Invention

[0010] The purpose of this invention is to solve the technical problems of existing time-reversal technology, such as its high dependence on external physical environment multipath and the high complexity and hardware cost of system implementation. It provides a low bit error rate antenna based on time reversal. By designing a passive subwavelength modulation structure in the antenna body, a stable "pre-scattering" environment is actively constructed in the near field region, thereby reducing the bit error rate of the wireless communication link at the physical level.

[0011] The technical problem addressed by this invention is solved as follows:

[0012] A time-reversal-based low bit error rate antenna includes a monopole antenna, a coaxial feed structure, and a high-order mode falloff wave auxiliary structure. The monopole antenna is located at the center and has a length of 0.37λ, where λ is the free-space wavelength corresponding to the antenna's operating center frequency. The coaxial feed structure provides an excitation source for the monopole antenna. The high-order mode falloff wave auxiliary structure is a three-layer one-dimensional barrel-shaped planar structure concentrically nested around the monopole antenna. The one-dimensional barrel-shaped planar structure includes a dielectric substrate and a metal wire array mounted on its surface. The radius and height of the three-layer one-dimensional barrel-shaped planar structure increase sequentially from the inside to the outside with an equal subwavelength gradient. The number of metal wires in the three-layer one-dimensional barrel-shaped planar structure increases arithmetically from the inside to the outside.

[0013] Furthermore, the radius of the monopole antenna is 0.9 mm; the radius of the inner one-dimensional barrel-shaped planar structure is 3.15 mm, and the radius of the three-layer one-dimensional barrel-shaped planar structure increases sequentially from the inside to the outside with a subwavelength gradient of 1.15 mm.

[0014] Furthermore, the number of metal wires in the inner one-dimensional barrel-shaped planar structure, the middle one-dimensional barrel-shaped planar structure, and the outer one-dimensional barrel-shaped planar structure are 12, 24, and 36, respectively, with a wire width of 0.2 mm and a thickness of 0.035 mm.

[0015] Furthermore, the heights of the inner one-dimensional barrel-shaped planar structure, the middle one-dimensional barrel-shaped planar structure, and the outer one-dimensional barrel-shaped planar structure are 37mm, 38mm, and 39mm, respectively.

[0016] Furthermore, the antenna operates in the 2.2GHz to 2.6GHz frequency band.

[0017] Furthermore, to verify the effectiveness of the antenna described in this invention in reducing the physical layer bit error rate, a communication verification system was constructed, and five time-reversal mirrors (TRMs) operating in the 2.2 GHz to 2.6 GHz wideband frequency band were configured; the spacing between adjacent TRMs was 0.8λ, and the distance between the source antenna and the TRM array was 10λ.

[0018] Three sets of communication transmission experiments were set up:

[0019] Group A: The source antenna is a monopole antenna, placed in a free-space line-of-sight channel;

[0020] Group B: The source antenna is the low bit error rate antenna described in this invention, and it is placed in the same free space line-of-sight channel as Group A;

[0021] Group C: The source antenna is the low bit error rate antenna described in this invention, placed in a non-line-of-sight rich multipath channel composed of densely distributed metal components;

[0022] Group A and Group B comparative experiments were used to verify the effect of the antenna of the present invention on reducing the bit error rate in communication transmission in a non-complex electromagnetic environment; Group B and Group C comparative experiments were used to verify that the antenna of the present invention has a better effect on reducing the bit error rate in communication transmission in a complex electromagnetic environment.

[0023] Furthermore, during the three sets of communication transmission experiments:

[0024] Channel detection: The source antenna transmits an initial probe pulse signal, which is received by the TRM array to extract the channel impulse response; for group A, the received signal is amplified and then fed back to the source antenna; for groups B and C, the received signal is time-reversed in the digital baseband.

[0025] Time-reversed transmission: The TRM transmits the time-reversed signal as an excitation signal;

[0026] Bit error rate calculation: The source antenna receives the signal transmitted by the TRM and performs bit error rate statistics and comparison on the demodulated tethered data.

[0027] The beneficial effects of this invention are:

[0028] (1) Near-field radiation enhancement based on high-order mode falloff wave conversion

[0029] Existing phased array or multi-antenna systems typically rely on expensive transceiver (T / R) components and complex feeding networks to achieve beamforming. This invention innovatively employs a three-layer subwavelength gradient wire array as an auxiliary structure for high-order mode evanescent waves, strongly coupled to the central monopole. This microstructure scatterer effectively breaks the impedance mismatch in the near-field region of the monopole, extracting and transforming the non-radiative evanescent waves originally confined to the antenna's near-field region into propagating waves radiating to the far field. This significantly enhances the spatial phase complexity and degrees of freedom of the transmitted signal without requiring additional active RF devices.

[0030] (2) Deterministic prescattering channel reconstruction of antenna body integration

[0031] Traditional time-reversal (TR) technology's time-reversal gain and spatiotemporal focusing performance are highly dependent on random multipath effects generated by the external environment (such as indoor walls, furniture, etc.), resulting in extremely poor environmental robustness. This invention overcomes this limitation by using a multi-layered metal wire array integrated into the antenna for "pre-scattering," actively and stably constructing abundant multipath components at the transmitter. This structure allows the channel impulse response (CIR) acquired at the receiver (TRM) to carry the stable high-frequency spatial characteristics imparted by the antenna itself. When performing time-reversal reverse transmission, more intense time-domain compression and energy focusing can be excited at the radiator's dedicated physical structure, achieving active channel optimization.

[0032] (3) Low hardware overhead and high environmental robustness physical layer anti-fading

[0033] To address the high cost of large-pitch antenna arrays and the deep fading issues inherent in traditional monopole antennas in complex reflection environments, this invention innovatively replaces complex baseband equalization algorithms and large-scale active arrays with a purely passive antenna structure. Experiments show that in complex electromagnetic environments with severe multipath interference and shadow fading, compared to traditional monopole communication systems, this invention's solution reduces the bit error rate (BER) by approximately 30% without increasing system power consumption. This solution significantly reduces engineering implementation difficulty and greatly improves the robustness and reliability of the communication system. Attached Figure Description

[0034] Figure 1 This is a front view of the antenna described in this invention;

[0035] Figure 2 This is a top view of the antenna described in this invention;

[0036] Figure 3 This is a schematic diagram of the architecture of the communication verification system described in the embodiment;

[0037] Figure 4 This is a graph showing the S-parameters of the antenna described in the embodiment;

[0038] Figure 5 The far-field radiation pattern of the antenna described in the embodiment;

[0039] Figure 6 This is a waveform diagram of the QPSK modulated signal transmitted by the source antenna as described in the embodiment;

[0040] Figure 7 This is a bar chart showing the bit error rate of three sets of experiments in the example.

[0041] Figure 8 This is a schematic diagram illustrating the application scenario of the antenna described in the embodiment. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] This embodiment provides a low bit error rate antenna based on time reversal, such as... Figure 1As shown, the structure includes a monopole antenna, a coaxial feed structure, and a high-order mode fallout wave auxiliary structure. The monopole antenna is located at the center and has a length of 0.37λ, where λ is the free-space wavelength corresponding to the antenna's operating center frequency. The coaxial feed structure is located at the bottom of the monopole antenna and provides an excitation source. The high-order mode fallout wave auxiliary structure is a three-layer one-dimensional barrel-shaped planar structure concentrically nested around the monopole antenna. The one-dimensional barrel-shaped planar structure includes a dielectric substrate and a metal wire array mounted on its surface. The radius and height of the three-layer one-dimensional barrel-shaped planar structure increase arithmetically from the inside to the outside with a subwavelength gradient. The number of metal wires in the three-layer one-dimensional barrel-shaped planar structure increases arithmetically from the inside to the outside. The high-order mode fallout wave auxiliary structure actively constructs a high-degree-of-freedom deterministic "pre-scattering" environment at the transmitting end by efficiently extracting and converting near-field non-radiative fallout waves into propagating waves, completely decoupling the dependence on external random multipath channels from the physical level.

[0044] In this embodiment, the radius of the monopole antenna is 0.9 mm. To achieve optimal extraction and scattering modulation of the falling wave, the radius of the three-layer one-dimensional barrel-shaped planar structure increases sequentially from the inside to the outside with a subwavelength gradient of 1.15 mm, and the radius of the inner one-dimensional barrel-shaped planar structure is 3.15 mm. The number of metal wires in the inner, middle, and outer one-dimensional barrel-shaped planar structures are 12, 24, and 36, respectively, with a wire width of 0.2 mm and a thickness of 0.035 mm, forming a high-density electromagnetic metasurface structure.

[0045] The antenna described in this embodiment operates in the 2.2GHz to 2.6GHz frequency band.

[0046] Figure 4 The image shows the S-parameter curve of the antenna described in this embodiment, which exhibits excellent broadband impedance matching characteristics. Figure 5 The far-field radiation pattern of the antenna described in this embodiment shows good omnidirectional coverage and gain flatness. This antenna exhibits excellent radiation characteristics within its operating frequency band.

[0047] To verify the effectiveness of the antenna described in this embodiment in spatial channel reconstruction and reducing the physical layer bit error rate, a communication verification system including a time-reversal mirror (TRM) array was constructed, such as... Figure 3 As shown. In this communication verification system, five time-reversal mirror (TRM) antennas operating in the 2.2GHz to 2.6GHz wideband frequency band serve as transceiver base stations.

[0048] This embodiment establishes three sets of strictly controlled communication transmission experiments to verify the bit error rate reduction effect of the antenna described in this embodiment during communication transmission:

[0049] Group A (Benchmark Control Group): The source antenna is a monopole antenna, placed in a free-space line-of-sight channel (environment without complex obstacles).

[0050] Group B (Antenna Mechanism Verification Group as described in this embodiment): The source antenna is the low bit error rate antenna as described in this embodiment, placed in the same free space channel;

[0051] Group C (Antenna Extreme Operating Condition Verification Group as described in this embodiment): The source antenna is the low bit error rate antenna described in this embodiment, placed in a non-line-of-sight multipath channel (complex electromagnetic environment) composed of densely packed metal components.

[0052] All experimental groups had the same distance between the source antenna and the TRM, which was 10λ; the spacing between the 5 TRMs was 0.8λ.

[0053] The communication verification process is as follows:

[0054] Channel detection (detection phase): The source antenna transmits an initial probe pulse signal, which is received by the remote TRM antenna array to extract the channel impulse response (CIR) of the current link. For group A, the received signal is directly amplified and precoded. For groups B and C, the TRM performs time reversal operation on the received signal in the digital baseband, that is, the signal is flipped in the time domain and conjugated before precoding.

[0055] Time-reversal transmission (communication phase): The TRM antenna retransmits the time-reversed pre-coded signal as an excitation signal; due to the high-order mode scattering structure specially configured in this embodiment, the electromagnetic wave will undergo phase conjugate matching at the physical space of the source antenna during back propagation, forming spatial energy convergence.

[0056] Bit Error Rate (BER) Calculation (Evaluation Phase): The source antenna receives downlink communication data and performs BER statistics and comparison on the demodulated baseband data.

[0057] In this embodiment, group A and group B comparative experiments are used to verify the effect of the antenna of the present invention on reducing the bit error rate in communication transmission under conditions without complex electromagnetic environments; group B and group C comparative experiments are used to verify that the antenna of the present invention has a better effect on reducing the bit error rate in communication transmission under complex electromagnetic environments. Multiple sets of comparative experiments under free-space channels (corresponding to the original environment without complex electromagnetic environments) and multipath-rich scattering channels (corresponding to the original complex electromagnetic environments) show that, at the same transmission distance (10λ), the radiator designed in this invention, after time-reversal precoding processing, can significantly improve the spatiotemporal focusing gain at the target location.

[0058] In this embodiment, the waveform of the QPSK modulated signal transmitted by the source antenna is shown below. Figure 6 As shown in the figure. The bit error rate histograms for the three sets of experiments are as follows. Figure 7As shown, it is intuitively demonstrated that in the complex electromagnetic scattering environment of Group C, traditional signals are extremely prone to severe inter-symbol interference (ISI) due to multipath delay spread; while the antenna of this invention, through its built-in "pre-scattering" microstructure and time reversal mechanism, not only becomes immune to the adverse effects of the external environment, but also utilizes multipath energy, successfully reducing the link bit error rate by about 30% compared with ordinary monopole antennas under the same conditions.

[0059] like Figure 8 The typical application scenario shown demonstrates that in indoor environments with severe multipath reflection (such as living rooms with densely packed appliances and furniture), smart terminal devices (televisions, mobile phones, tablets, etc.) equipped with the low bit error rate antenna of this invention can autonomously construct high-quality, highly reliable communication links when conducting time-reversal bidirectional communication with routers / base stations, effectively solving the fading problem in high-speed wireless communication from the hardware level.

[0060] In summary, this invention discloses a low bit error rate antenna design based on high-order mode fallout wave assistance and time inversion joint control. It employs a coaxially fed monopole as the main radiation source and innovatively couples three layers of one-dimensional planar metal wire arrays with increasing subwavelength gradients in the near field around it. Through the efficient extraction and propagation wave conversion of near-field non-radiative fallout waves by this passive microstructure, this invention actively constructs a highly free deterministic "pre-scattering" environment at the transmitter. This mechanism completely decouples the heavy dependence of traditional time inversion technology on external random multipath channels from a physical level, endowing the communication link with extremely strong environmental robustness. Within the 2.2GHz to 2.6GHz wide operating range, the antenna of this invention, in conjunction with a far-end time inversion mirror (TRM) array, perfectly achieves the ultimate spatiotemporal focusing of electromagnetic waves in complex channels. Compared to traditional phased arrays that rely on large feeding networks and expensive phase shifters, the passive antenna design of this invention completely avoids the hardware barriers of high-cost active T / R components. Experiments have demonstrated that in non-line-of-sight (NLoS) multipath fading scenarios with severe delay spread, this scheme can significantly reduce the transmission bit error rate by approximately 30% compared to traditional monopole antennas. This invention, while greatly simplifying the system hardware architecture and reducing engineering deployment costs, provides a disruptive new paradigm for physical-layer anti-fading in highly reliable wireless communication under complex electromagnetic environments.

Claims

1. A low bit error rate antenna based on time inversion, characterized in that, It includes a monopole antenna, a coaxial feed structure, and a high-order mode falloff wave auxiliary structure; the monopole antenna is located at the center position and has a length of 0.37λ, where λ is the free space wavelength corresponding to the antenna's operating center frequency; the coaxial feed structure is used to provide an excitation source for the monopole antenna; the high-order mode falloff wave auxiliary structure is a three-layer one-dimensional barrel-shaped planar structure concentrically nested around the monopole antenna; the one-dimensional barrel-shaped planar structure includes a dielectric substrate and a metal wire array mounted on its surface; The radius and height of the three-layer one-dimensional barrel-shaped planar structure increase arithmetically from the inside to the outside with a subwavelength gradient; the number of metal wires in the three-layer one-dimensional barrel-shaped planar structure increases arithmetically from the inside to the outside.

2. The low bit error rate antenna based on time inversion according to claim 1, characterized in that, The radius of the monopole antenna is 0.9 mm; the radius of the inner one-dimensional barrel-shaped planar structure is 3.15 mm, and the radius of the three-layer one-dimensional barrel-shaped planar structure increases sequentially from the inside to the outside with a subwavelength gradient of 1.15 mm.

3. The low bit error rate antenna based on time inversion according to claim 1, characterized in that, The inner one-dimensional barrel-shaped planar structure, the middle one-dimensional barrel-shaped planar structure, and the outer one-dimensional barrel-shaped planar structure have 12, 24, and 36 metal wires, respectively. The width of the metal wires is 0.2 mm and the thickness is 0.035 mm.

4. The low bit error rate antenna based on time inversion according to claim 1, characterized in that, The antenna operates in the 2.2GHz to 2.6GHz frequency band.

5. The low bit error rate antenna based on time inversion according to claim 1, characterized in that, To verify the effectiveness of the antenna described in claim 1 in reducing the physical layer bit error rate, a communication verification system was constructed, which was configured with five time-reversal mirrors (TRMs) operating in a wideband frequency band from 2.2 GHz to 2.6 GHz; the spacing between adjacent TRMs was 0.8λ, and the distance between the source antenna and the TRM array was 10λ. Three sets of communication transmission experiments were set up: Group A: The source antenna is a monopole antenna, placed in a free-space line-of-sight channel; Group B: The source antenna is the low bit error rate antenna as described in claim 1, and is placed in the same free-space line-of-sight channel as Group A; Group C: The source antenna is the low bit error rate antenna as described in claim 1, placed in a non-line-of-sight rich multipath channel composed of densely distributed metal components; Group A and Group B comparative experiments were used to verify the effect of the antenna described in claim 1 on reducing the bit error rate in communication transmission in a non-complex electromagnetic environment; Group B and Group C comparative experiments were used to verify that the antenna described in claim 1 has a better effect on reducing the bit error rate in communication transmission in a complex electromagnetic environment.

6. The low bit error rate antenna based on time inversion according to claim 5, characterized in that, During the three sets of communication transmission experiments: Channel detection: The source antenna transmits an initial probe pulse signal, which is received by the TRM array to extract the channel impulse response; for group A, the received signal is amplified and then fed back to the source antenna; for groups B and C, the received signal is time-reversed in the digital baseband. Time-reversed transmission: The TRM transmits the time-reversed signal as an excitation signal; Bit error rate calculation: The source antenna receives the signal transmitted by the TRM and performs bit error rate statistics and comparison on the demodulated tethered data.

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