A vehicle-mounted Ethernet millimeter-wave full-duplex wireless communication device for rail transit

Abstract

This invention belongs to the field of communication technology, specifically a vehicle-mounted Ethernet millimeter-wave full-duplex wireless communication device for rail transit, comprising: a first device, a second device, a third device, and a fourth device; the first, second, third, and fourth devices are all configured to realize full-duplex wireless transmission of Ethernet-millimeter-wave-Ethernet, wherein the antenna polarization directions of the first and second devices are the same, forming a first wireless link for full-duplex communication; the antenna polarization directions of the third and fourth devices are the same, forming a second wireless link for full-duplex communication; the millimeter-wave signals transmitted in the first and second wireless links are orthogonal to each other and isolated from each other to achieve redundant transmission or expand communication capacity. This invention can simplify train formation and maintenance, provide higher data transmission rates and lower latency, and meet the real-time requirements of high-speed trains.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to an onboard Ethernet millimeter-wave full-duplex wireless communication device for rail transit. Background Technology

[0002] With the continuous development of intelligent train driving technology, the amount of data that needs to be transmitted has increased significantly. This data includes train control systems, monitoring systems, and passenger service systems. Millimeter wave technology, with its high bandwidth and low latency, can provide high-speed data transmission capabilities for intelligent train driving, meeting its demand for large data transmission volumes.

[0003] During train operation, various electromagnetic interferences are inevitable. Millimeter-wave technology, with its narrow beam and good directionality, possesses strong anti-interference capabilities, ensuring stable communication even in complex electromagnetic environments. Intelligent driving systems require real-time responses to various emergencies, and the low latency of millimeter-wave communication guarantees real-time information transmission, which is crucial for safe train operation. Intelligent train driving involves the interconnection of numerous onboard devices and systems, and millimeter-wave technology provides high-speed wireless connections between these devices, strongly supporting the construction of onboard networks and the effective operation of intelligent driving functions. Furthermore, millimeter-wave technology has strong penetration capabilities, maintaining communication stability even in adverse weather conditions, which is of great significance for ensuring the safe operation of trains in various environments.

[0004] With the development of intelligent railways, millimeter-wave technology will play a crucial role in train automatic driving, train safety video surveillance, train status monitoring, and remote fault diagnosis. It has become the information carrier platform for the railway Internet of Things and the foundation for ensuring the safe operation of high-speed railways. Currently, communication between carriages in high-speed trains is mainly achieved through wired cables. This connection method can achieve stable transmission of train control signals and has a relatively high transmission rate, but it requires laying a large number of cables between the various carriages of the train, which undoubtedly increases the complexity of the system and the difficulty of maintenance. At the same time, when the train formation changes, rewiring or making corresponding adjustments is difficult. Compared with wired transmission, existing rail transit on-board wireless communication technology still has problems such as large transmission delay, lower communication speed than wired communication, and poor security and reliability. Summary of the Invention

[0005] The purpose of this invention is to provide an onboard Ethernet millimeter-wave full-duplex wireless communication device for rail transit, which solves the problem of complex wired cable layout between existing train carriages while realizing high-speed, low-latency, high-security, full-duplex millimeter-wave communication.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A vehicle-mounted Ethernet millimeter-wave full-duplex wireless communication device for rail transit includes: a first device, a second device, a third device, and a fourth device.

[0008] The first, second, third, and fourth devices are all configured to achieve full-duplex wireless transmission from Ethernet to millimeter wave to Ethernet. The antenna polarization directions of the first and second devices are the same (horizontal or vertical), forming the first wireless link for full-duplex communication. The antenna polarization directions of the third and fourth devices are the same (vertical or horizontal), forming the second wireless link for full-duplex communication. The polarization directions of the first and second devices and the third and fourth devices can be either vertical or horizontal, but cannot be in the same state simultaneously. This results in the millimeter wave signal polarization directions transmitted by the first and second wireless links being orthogonal to each other and isolated from each other, in order to achieve redundant transmission or expand communication capacity.

[0009] Furthermore, the first device, the second device, the third device, and the fourth device each include: an electrical port module, a millimeter-wave transmitting link, and a millimeter-wave receiving link;

[0010] The electrical port module connects to an externally input Ethernet signal or a baseband signal provided by a millimeter-wave receiving link. It converts the Ethernet signal into an OOK baseband signal and outputs it to the millimeter-wave transmitting link, and restores the baseband signal provided by the millimeter-wave receiving link into an Ethernet signal for output.

[0011] The millimeter-wave transmission link includes: a first baseband low-pass filter, a millimeter-wave local oscillator, a millimeter-wave up-converter, a millimeter-wave VGA, a millimeter-wave power amplifier, a millimeter-wave duplexer, and a millimeter-wave antenna. The first baseband low-pass filter receives the OOK baseband signal provided by the interface module, performs band-limiting processing, and then transmits it to the millimeter-wave up-converter. The millimeter-wave local oscillator provides a millimeter-wave sine wave signal to the millimeter-wave up-converter. The millimeter-wave up-converter modulates the millimeter-wave sine wave signal according to the band-limited OOK baseband signal to obtain a millimeter-wave amplitude-modulated signal, which is then transmitted to the millimeter-wave VGA. The millimeter-wave VGA and the millimeter-wave power amplifier are cascaded to regulate the amplitude of the millimeter-wave amplitude-modulated signal, and the regulated millimeter-wave amplitude-modulated signal is filtered by the millimeter-wave duplexer and then transmitted to the millimeter-wave antenna. The millimeter-wave antenna radiates the filtered millimeter-wave amplitude-modulated signal into free space.

[0012] The millimeter-wave receiving link includes: a millimeter-wave antenna, a millimeter-wave duplexer, a millimeter-wave low-noise amplifier, a directional coupler, a power control device, an envelope detector, and a second baseband low-pass filter. The millimeter-wave antenna receives millimeter-wave amplitude-modulated (AM) signals propagating in free space and transmits them to the millimeter-wave duplexer. The millimeter-wave duplexer filters the received AM signals and transmits the filtered AM signals to the millimeter-wave low-noise amplifier. The millimeter-wave low-noise amplifier amplifies the filtered AM signals and transmits them to the input of the directional coupler. The coupling end of the directional coupler is connected to the power control device, providing direct access. The device connects to an envelope detector; a power detection unit is used to detect the millimeter-wave power coupled to the directional coupler in real time, and generates a voltage control signal based on the detected millimeter-wave power, which is transmitted to the millimeter-wave VGA to adjust the transmission power in real time to cope with the impact of different environmental and climatic conditions on the quality of millimeter-wave wireless communication; the envelope detector uses an incoherent demodulation method to demodulate the millimeter-wave amplitude-modulated signal, and the resulting OOK baseband signal is transmitted to a second baseband low-pass filter for filtering. The second baseband low-pass filter transmits the filtered OOK baseband signal to the Ethernet module for signal conversion, and finally restores it to an Ethernet signal.

[0013] Furthermore, the power control device includes: a millimeter-wave amplifier, a power detector, an ADC, a microprocessor, a memory, and a DAC;

[0014] The input terminal of the millimeter-wave amplifier is connected to the coupling terminal of the directional coupler, which is used to amplify the coupled millimeter-wave amplitude-modulated signal and transmit it to the power detector.

[0015] The power detector is used to convert the amplified millimeter-wave amplitude-modulated signal into a voltage output.

[0016] The ADC is responsible for sampling and measuring the output voltage of the power detector, and transmitting the sampled and measured data to the microprocessor.

[0017] The microprocessor reads the calibration coefficients pre-written in the memory based on the sampling data obtained by the ADC, calibrates and calculates the millimeter-wave power, and finally outputs a voltage control signal that is transmitted to the DAC.

[0018] The DAC performs digital-to-analog conversion on the received voltage control signal and then sends it to the millimeter-wave VGA.

[0019] Furthermore, the power detector is an RMS detector, a logarithmic detector, or other power detector that operates in the millimeter-wave frequency band.

[0020] Furthermore, the bandwidth of the electrical port module needs to be greater than the Ethernet bandwidth R. b The cutoff frequency f of the first baseband low-pass filter and the second baseband low-pass filter LPFIt should be greater than R b .

[0021] Furthermore, the millimeter-wave duplexer comprises a first waveguide filter, a second waveguide filter, and a waveguide common terminal; the passband center frequencies of the first waveguide filter and the second waveguide filter are f1 and f2, respectively, and their 3dB bandwidths are BW1 and BW2, respectively. The frequency guard interval is Δf = |f1-f2|-(BW1+BW2) / 2, where f1, f2, BW1, BW2, and Δf are all greater than 0, and BW1 and BW2 are both greater than R. b The millimeter-wave duplexer has three waveguide ports: a first port, a second port, and a third port. These three ports correspond to a first waveguide filter, a second waveguide filter, and a common waveguide terminal, respectively. In the millimeter-wave transmit link, the first port is connected to the output port of the millimeter-wave power amplifier, the second port is connected to the input port of the millimeter-wave low-noise amplifier, and the third port is connected to the waveguide port of the millimeter-wave antenna. In the millimeter-wave receive link, the first port is connected to the input port of the millimeter-wave low-noise amplifier, the second port is connected to the output port of the millimeter-wave power amplifier, and the third port is connected to the waveguide port of the millimeter-wave antenna. The millimeter-wave duplexer enables simultaneous reception and transmission of signals without interference, thereby achieving full-duplex communication.

[0022] The aforementioned vehicle-mounted Ethernet millimeter-wave full-duplex wireless communication device for rail transit includes the following steps for implementing Ethernet millimeter-wave full-duplex wireless communication:

[0023] S1. Power on the Nth (N is 1, 2, 3, 4) device. The electrical port module of this device starts to receive the Ethernet signal sent by the switch and convert it into the OOK baseband signal output by the radio frequency coaxial interface.

[0024] S2. Band-limit the baseband OOK signal using the first baseband low-pass filter;

[0025] S3, the carrier frequency generated by the millimeter-wave local oscillator is f c_N The millimeter-wave sine wave signal is transmitted to the millimeter-wave up-converter. The millimeter-wave up-converter modulates the millimeter-wave sine wave signal according to the band-limited OOK baseband signal, resulting in a frequency range of [f]. c_N -Rb,f c_N +Rb] millimeter-wave amplitude-modulated signal;

[0026] S4. First, the millimeter-wave VGA and millimeter-wave power amplifier are cascaded. This cascaded combination is used to amplify the power of the millimeter-wave amplitude modulation signal. Then, a millimeter-wave duplexer is used for filtering. Finally, the millimeter-wave antenna transmitter radiates the processed millimeter-wave amplitude modulation signal into free space.

[0027] S5. Receive the millimeter-wave amplitude-modulated signal from free space using a millimeter-wave antenna receiver. Then, filter the millimeter-wave amplitude-modulated signal using a millimeter-wave duplexer, and finally pass it through a millimeter-wave low-noise amplifier (with a gain of G). LNA The filtered millimeter-wave amplitude-modulated signal is amplified, and then the amplified millimeter-wave amplitude-modulated signal is simultaneously transmitted to the envelope detector and the power control device by a directional coupler (with coupling degree C).

[0028] S6. The power control device contains a power detector and a microprocessor. First, the power detector converts the amplified millimeter-wave amplitude-modulated signal into a voltage. The output voltage Vout of the power detector is measured, and the slope and intercept of the power detector are known. Then, the microprocessor calculates the actual received power Pr = Vout / Slope + Intercept + C - Ga - G. LNA Then, based on the set expected received power P SET Power decision is made using (dBm) and allowable error M (dB) |Pr-P SET |Is it less than M? If yes, envelope detection is performed; if no, a control signal is output to the millimeter-wave VGA to continuously adjust the transmit power until the receive power is within the allowable error M.

[0029] S7. An envelope detector is used to perform envelope detection on the millimeter-wave signal that is directly connected to the directional coupler to obtain the baseband OOK signal. After passing through the second baseband low-pass filter, it is finally recovered into an Ethernet signal through the electrical port module, thus realizing full-duplex wireless communication of Ethernet millimeter-wave signals.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention employs an Ethernet-millimeter wave full-duplex wireless communication scheme implemented with amplitude modulation and incoherent demodulation technology, which can effectively replace the existing wired cables with complex layouts and difficult arrangement between train carriages.

[0032] 2. In this invention, the signal frequencies of the millimeter-wave transmitting link and the millimeter-wave receiving link in the wireless communication device are different. This invention achieves simultaneous transmission and reception of signals through a millimeter-wave duplexer, that is, it adopts frequency division multiplexing technology, which improves channel utilization.

[0033] In this invention, the polarization directions of the first and second devices and the third and fourth devices are both vertical and horizontal, but cannot be in the same state at the same time. This is to ensure that the polarization directions of the millimeter-wave signals transmitted by the first wireless link and the second wireless link are orthogonal to each other and isolated from each other, so as to achieve redundant transmission or expand communication capacity. That is, polarization multiplexing technology is adopted.

[0034] 3. The present invention employs a power control device that detects, calculates, and determines the power of the received millimeter-wave amplitude-modulated signal in real time, and adjusts the transmission power in real time, thereby addressing the impact of different environmental and climatic conditions on the quality of millimeter-wave wireless communication. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0036] Figure 1 This is a schematic diagram illustrating the application scenario and installation of the vehicle-mounted Ethernet millimeter-wave full-duplex wireless communication device for rail transit described in this invention.

[0037] Figure 2 This is a system block diagram of the onboard Ethernet millimeter-wave full-duplex wireless communication device for rail transit described in this invention;

[0038] Figure 3 This is a system block diagram of the power control device described in this invention;

[0039] Figure 4 This is a flowchart illustrating the design of the onboard Ethernet millimeter-wave full-duplex wireless communication solution for rail transit as described in this invention.

[0040] The specific labeling in the attached diagram is as follows:

[0041] 201 - Electrical port module; 202 - First baseband low-pass filter; 203 - Millimeter-wave local oscillator; 204 - Millimeter-wave up-converter; 205 - Millimeter-wave VGA; 206 - Millimeter-wave power amplifier; 207 - Millimeter-wave duplexer; 208 - Millimeter-wave antenna; 209 - Millimeter-wave low-noise amplifier; 210 - Directional coupler; 211 - Power control device; 212 - Envelope detector; 213 - Second baseband low-pass filter; 301 - Millimeter-wave amplifier; 302 - Power detector; 303 - ADC; 304 - Microprocessor; 305 - Memory; 306 - ADC. Detailed Implementation

[0042] 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 embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and are not intended to limit the invention. The technical solutions of this invention are described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Figure 1This embodiment illustrates an application scenario and installation diagram of an onboard Ethernet millimeter-wave full-duplex wireless communication device for rail transit. (See also...) Figure 1 The wireless communication device includes:

[0044] Device 1, Device 2, Device 3, Device 4;

[0045] The first, second, third, and fourth devices all employ frequency division multiplexing technology and each includes a millimeter-wave transmission link and a millimeter-wave reception link that are isolated from each other, enabling full-duplex communication.

[0046] The first, second, third, and fourth devices convert the gigabit Ethernet signal provided by the vehicle-mounted switch into millimeter wave signal for wireless transmission, ultimately achieving full-duplex wireless transparent transmission of Ethernet-millimeter wave-Ethernet.

[0047] The antennas of the first and second devices are horizontally polarized, forming the first wireless link for full-duplex communication;

[0048] The antennas of the third and fourth devices are vertically polarized, forming a second wireless link for full-duplex communication.

[0049] Figure 2 This is a system block diagram of the first, second, third, and fourth devices provided in this embodiment. Each device includes: an electrical port module 201; a first baseband low-pass filter 202; a millimeter-wave local oscillator 203; a millimeter-wave up-converter 204; a millimeter-wave VGA 205; a millimeter-wave power amplifier 206; a millimeter-wave duplexer 207; a millimeter-wave antenna 208; a millimeter-wave low-noise amplifier 209; a directional coupler 210; a power control device 211; an envelope detector 212; and a second baseband low-pass filter 213. The first baseband low-pass filter 202 has its input terminal connected to the electrical port module 201 and its output terminal connected to the first input terminal of the millimeter-wave up-converter 204. The second input terminal of the millimeter-wave up-converter 204 is connected to... The millimeter-wave local oscillator 203 has its output connected sequentially to the first input of a millimeter-wave duplexer 207 via a millimeter-wave VGA 205 and a millimeter-wave power amplifier 206. The first output of the millimeter-wave duplexer 207 is connected to the transmitting end of a millimeter-wave antenna 208. The receiving end of the millimeter-wave antenna 208 is connected to the second input of the millimeter-wave duplexer 207. The second output of the millimeter-wave duplexer 207 is connected to the input of a directional coupler 210 via a millimeter-wave low-noise amplifier 209. The coupling end of the directional coupler 210 is connected to the input of a power control device 211, and its through end is connected sequentially to an envelope detector 212 and a second low-pass filter 213 via an electrical port module 201. The output of the power controller device is connected to the millimeter-wave VGA 205.

[0050] In this embodiment, the millimeter-wave local oscillator 203 is used to generate a carrier frequency f.c The millimeter-wave sinusoidal single-tone signal provides a local oscillator drive signal for the millimeter-wave up-converter. The harmonic and spurious suppression of the millimeter-wave local oscillator 203 generally needs to be better than 30dBc. The millimeter-wave VGA 205 is used to controllably amplify or attenuate the amplitude of the millimeter-wave amplitude-modulated signal generated by the millimeter-wave up-converter 204, and adjust the transmission power in real time to cope with the free-space transmission loss fluctuations of the wireless link under different scenarios. The millimeter-wave VGA includes four interfaces: input, output, gain control, and DC power supply. The gain control interface receives the gain control signal issued by the power control device 211 and immediately and dynamically changes its gain. The DC power supply interface is connected to a DC power supply.

[0051] In devices 1, 2, 3, and 4, the electrical port module converts the gigabit Ethernet signal into a coaxial output OOK baseband signal at a rate of 1000 Mbps. The cutoff frequency f of the low-pass filter... LPF The frequency is 1.5 GHz. The millimeter-wave local oscillator frequencies (N = 1, 2, 3, 4) are set to f1, f2, f1, f2 respectively, with harmonic and spurious suppression of 40 dBc. In devices 1, 2, 3, and 4, the center frequencies of the two filter passbands of the millimeter-wave duplexer are f1 and f2, with passband bandwidths greater than 1 GHz, and they are isolated from each other.

[0052] In the first, second, third, and fourth devices, the frequencies of the transmitted millimeter-wave signals are [f1-1GHz, f1+1GHz], [f2-1GHz, f2+1GHz], [f1-1GHz, f1+1GHz], and [f1-1GHz, f1+1GHz], respectively, and the polarization directions of the transmitted millimeter-wave signals are horizontal, horizontal, vertical, and vertical, respectively. The frequencies of the received millimeter-wave signals are [f2-1GHz, f2+1GHz], [f1-1GHz, f1+1GHz], [f1-1GHz, f1+1GHz], and [f1-1GHz, f1+1GHz], respectively, and the polarization directions of the transmitted millimeter-wave signals are horizontal, horizontal, vertical, and vertical, respectively.

[0053] In devices 1, 2, 3, and 4, the directional coupler is a branch waveguide coupler with a coupling degree of 10dB.

[0054] In the first, second, third, and fourth devices, the RF operating bandwidth of the envelope detector covers the frequency range of the received millimeter-wave signal, and the detection video bandwidth is greater than 1 GHz.

[0055] Figure 3 This is a system block diagram of the power control device in the first, second, third, and fourth devices provided in the embodiments of this disclosure, as shown below. Figure 3As shown, the power control device includes: a millimeter-wave amplifier 301, a power detector 302, an ADC 303, a microprocessor 304, a memory 305, and an ADC 306. The input of the millimeter-wave amplifier 301 is connected to a directional coupler, and its output is connected sequentially to the first input of the microprocessor 304 via the power detector 302 and the ADC 303. The second input of the microprocessor 304 is connected to the first output of the memory 305, and its output is connected to a millimeter-wave VGA via the DAC 306. The input of the memory 305 is connected to the second output of the microprocessor 304. The power detector 302 is used to detect the received millimeter-wave power in real time and calculate the wireless link loss, thereby adjusting the transmit power in real time to address the impact of different environmental and climatic conditions on the quality of millimeter-wave wireless communication. The ADC303 is responsible for sampling and measuring the output voltage of the power detector 302. The microprocessor 304 reads the calibration coefficients written in advance in the memory 305 based on the sampling data obtained by the ADC303, calibrates and calculates the millimeter-wave power, and finally outputs a voltage control signal, which is then converted from digital to analog by the DAC306 and sent to the millimeter-wave VGA205.

[0056] This embodiment takes the first device as an example to describe in detail the method for implementing Ethernet millimeter-wave full-duplex wireless communication in the above-mentioned vehicle-mounted Ethernet millimeter-wave full-duplex wireless communication device for rail transit. Figure 4 As shown, it includes the following steps:

[0057] S1. The first device is powered on and begins sending Ethernet signals;

[0058] S2. Determine the bandwidth of the Ethernet module (must be greater than Rb). The Ethernet module starts receiving the Ethernet signal sent by the switch and converts it into the OOK baseband signal output by the RF coaxial interface.

[0059] S2. Set the cutoff frequencies f of the first baseband low-pass filter and the second baseband low-pass filter. LPF It should satisfy f LPF >Rb; Band-limiting of the baseband OOK signal is performed using the first baseband low-pass filter;

[0060] S3. Set the frequency of the millimeter-wave local oscillator source of the first device to f1, and generate a carrier frequency of f1 through the millimeter-wave local oscillator source. c_N Millimeter-wave sinusoidal signal;

[0061] S4. Select a millimeter-wave up-converter. The operating frequency range of the millimeter-wave up-converter must cover the signal bandwidth [f1-Rb, f1+Rb]. The millimeter-wave up-converter modulates the millimeter-wave sine wave signal based on the received band-limited OOK baseband signal to obtain a frequency range of [f1-Rb]. c_N -Rb,f c_NMillimeter-wave amplitude-modulated signal with +Rb

[0062] S5. Set the gain of the millimeter-wave VGA (G VGA ), the gain of the millimeter-wave power amplifier (G PA ), and the output power (P out ); Set the polarization direction of the antenna (horizontal or vertical) to transmit the millimeter-wave signal; Use the millimeter-wave VGA and the millimeter-wave power amplifier to amplify the power of the millimeter-wave amplitude-modulated signal, and then use the millimeter-wave duplexer for filtering processing. Finally, the filtered millimeter-wave amplitude-modulated signal is radiated into free space by the transmitting end of the millimeter-wave antenna;

[0063] S5. Set the polarization direction of the antenna (horizontal or vertical) to receive the millimeter-wave signal. Use the receiving end of the millimeter-wave antenna to receive the millimeter-wave amplitude-modulated signal from free space and transmit it to the millimeter-wave duplexer for filtering. It should be noted that the receiving and transmitting polarization directions of the same device are orthogonal to each other, and the receiving and transmitting polarization directions of the same wireless link are the same;

[0064] S6. Set the gain of the millimeter-wave low-noise amplifier to G LNA , and set the coupling degree of the directional coupler to C. First, use the millimeter-wave low-noise amplifier to amplify the filtered millimeter-wave amplitude-modulated signal, and then the directional coupler simultaneously transmits the amplified millimeter-wave amplitude-modulated signal to the envelope detector and the power control device;

[0065] S6. The power control device is equipped with a power detector and a microprocessor. Use the power detector to detect the power of the millimeter-wave amplitude-modulated signal coupled by the directional coupler:

[0066] (1) First, use the power detector to convert the amplified millimeter-wave amplitude-modulated signal into voltage and measure the output voltage Vout of the power detector;

[0067] (2) In the microprocessor, calculate the actual received power Pr = Vout / Slope + Intercept + C - Ga - G LNA according to the output voltage Vout, the known slope Slope and intercept Intercept of the power detector;

[0068] (3) Perform power decision (|Pr - P SET (dBm)| < M?) according to the set expected received power P SET and the allowable error M (dB): If so, perform envelope detection; if not, output a control signal to the millimeter-wave VGA and continuously adjust the transmission power until the received power is within the allowable error M;

[0069] S7. The envelope detector performs envelope detection on the millimeter-wave signal directly connected to the directional coupler to obtain the baseband OOK signal. After passing through the second baseband low-pass filter, it is finally recovered into an Ethernet signal through the electrical port module, thus realizing full-duplex wireless communication of Ethernet millimeter-wave signals.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered as equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A vehicle-mounted Ethernet millimeter-wave full-duplex wireless communication device for rail transit, comprising: The first device, the second device, the third device, and the fourth device are characterized in that: The first, second, third, and fourth devices are all configured to achieve full-duplex wireless transmission from Ethernet to millimeter wave to Ethernet. The antennas of the first and second devices have the same polarization direction, forming the first wireless link for full-duplex communication; the antennas of the third and fourth devices have the same polarization direction, forming the second wireless link for full-duplex communication. The polarization directions of the first and second devices, and the third and fourth devices, each have two selectable states: vertical and horizontal, but cannot be in the same state simultaneously. This ensures that the millimeter wave signal polarization directions transmitted by the first and second wireless links are orthogonal and isolated from each other, thereby achieving redundant transmission or expanding communication capacity. The first, second, third, and fourth devices each include an Ethernet module, a millimeter-wave transmitting link, and a millimeter-wave receiving link. The Ethernet module receives an externally input Ethernet signal or a baseband signal provided by the millimeter-wave receiving link, converting the Ethernet signal into an OOK baseband signal for output to the millimeter-wave transmitting link, and restoring the baseband signal provided by the millimeter-wave receiving link back into an Ethernet signal for output. The bandwidth of the Ethernet module must be greater than the Ethernet bandwidth R. b ; The millimeter-wave transmission link includes: a first baseband low-pass filter, a millimeter-wave local oscillator, a millimeter-wave up-converter, a millimeter-wave VGA, a millimeter-wave power amplifier, a millimeter-wave duplexer, and a millimeter-wave antenna. The first baseband low-pass filter receives the OOK baseband signal provided by the interface module, performs band-limiting processing, and then transmits it to the millimeter-wave up-converter. The millimeter-wave local oscillator provides a millimeter-wave sine wave signal to the millimeter-wave up-converter. The millimeter-wave up-converter modulates the millimeter-wave sine wave signal according to the band-limited OOK baseband signal to obtain a millimeter-wave amplitude-modulated signal, which is then transmitted to the millimeter-wave VGA. The millimeter-wave VGA and the millimeter-wave power amplifier are cascaded to regulate the amplitude of the millimeter-wave amplitude-modulated signal, and the regulated millimeter-wave amplitude-modulated signal is filtered by the millimeter-wave duplexer and then transmitted to the millimeter-wave antenna. The millimeter-wave antenna radiates the filtered millimeter-wave amplitude-modulated signal into free space. The millimeter-wave receiving link includes: a millimeter-wave antenna, a millimeter-wave duplexer, a millimeter-wave low-noise amplifier, a directional coupler, a power control device, an envelope detector, and a second baseband low-pass filter. The millimeter-wave antenna receives millimeter-wave amplitude-modulated signals propagating in free space and transmits them to the millimeter-wave duplexer. The millimeter-wave duplexer filters the received millimeter-wave amplitude-modulated signals and transmits the filtered signals to the millimeter-wave low-noise amplifier. It consists of a first waveguide filter, a second waveguide filter, and a waveguide common terminal. In the millimeter-wave transmitting link, the first waveguide filter is connected to the output port of the millimeter-wave power amplifier. The first waveguide filter is also connected to the input port of the millimeter-wave low-noise amplifier, and the waveguide common terminal is connected to the waveguide port of the millimeter-wave antenna. In the millimeter-wave receiving link, the first waveguide filter is connected to the input port of the millimeter-wave low-noise amplifier, the second waveguide filter is connected to the output port of the millimeter-wave power amplifier, and the waveguide common terminal is connected to the waveguide port of the millimeter-wave antenna. A millimeter-wave low-noise amplifier amplifies the filtered millimeter-wave amplitude-modulated signal and transmits it to the input of a directional coupler. The coupling end of the directional coupler is connected to a power control device, and the through end is connected to an envelope detector. The power detection device detects the millimeter-wave power coupled to the directional coupler in real time and generates a voltage control signal based on the detected millimeter-wave power, which is then transmitted to the millimeter-wave VGA to adjust the transmit power in real time. The envelope detector demodulates the millimeter-wave amplitude-modulated signal using a non-coherent demodulation method, obtaining an OOK baseband signal, which is then transmitted to a second baseband low-pass filter for filtering. The second baseband low-pass filter transmits the filtered OOK baseband signal to the Ethernet module for signal conversion, ultimately restoring it to an Ethernet signal. The cutoff frequencies f of the first and second baseband low-pass filters are... LPF It should be greater than R b ; The power control device includes: a millimeter-wave amplifier, a power detector, an ADC, a microprocessor, a memory, and a DAC. The input terminal of the millimeter-wave amplifier is connected to the coupling terminal of a directional coupler, used to amplify the coupled millimeter-wave amplitude-modulated signal and transmit it to the power detector. The power detector is an RMS detector or a logarithmic detector operating in the millimeter-wave frequency band, used to convert the amplified millimeter-wave amplitude-modulated signal into a voltage output. The ADC is responsible for sampling and measuring the output voltage of the power detector and transmitting the sampled data to the microprocessor. The microprocessor reads the calibration coefficients pre-written in the memory based on the sampled data obtained from the ADC, calibrates and calculates the millimeter-wave power, and finally outputs a voltage control signal that is transmitted to the DAC. The DAC performs digital-to-analog conversion on the received voltage control signal and sends it to the millimeter-wave VGA.

2. The on-board Ethernet millimeter-wave full-duplex wireless communication device for rail transit according to claim 1, wherein the method for realizing Ethernet millimeter-wave full-duplex wireless communication includes the following steps: S1. Power on the Nth device. The electrical port module of this device begins to receive the Ethernet signal sent by the switch and converts it into an OOK baseband signal output by the RF coaxial interface; N is 1, 2, 3 or 4. S2. Band-limit the baseband OOK signal using the first baseband low-pass filter; S3. The millimeter-wave sinusoidal signal generated by the millimeter-wave local oscillator is transmitted to the millimeter-wave up-converter. The millimeter-wave up-converter modulates the millimeter-wave sinusoidal signal according to the OOK baseband signal after band limiting to obtain the millimeter-wave amplitude modulation signal. S4. First, the millimeter-wave VGA and millimeter-wave power amplifier are cascaded. This cascaded combination is used to amplify the power of the millimeter-wave amplitude modulation signal. Then, a millimeter-wave duplexer is used for filtering. Finally, the millimeter-wave antenna transmitter radiates the processed millimeter-wave amplitude modulation signal into free space. S5. Receive the millimeter-wave amplitude-modulated signal from free space using the millimeter-wave antenna receiver. Then, use a millimeter-wave duplexer to filter the millimeter-wave amplitude-modulated signal. After that, use a millimeter-wave low-noise amplifier to amplify the filtered millimeter-wave amplitude-modulated signal. Then, use a directional coupler to transmit the amplified millimeter-wave amplitude-modulated signal to the envelope detector and the power control device simultaneously. S6, the power control device, has a built-in power detector and microprocessor. The power detector is used to detect the power of the millimeter-wave amplitude-modulated signal coupled to the directional coupler. (1) First, use a power detector to convert the amplified millimeter-wave amplitude-modulated signal into voltage and measure its output voltage Vout. (2) Calculate the power Pr of the actually received millimeter-wave amplitude-modulated signal in the microprocessor based on the output voltage Vout, the slope of the known power detector, and the intercept: Pr=Vout / Slope+Intercept+C-Ga-G LNA ; (3) Based on the set expected received power P SET Power decision is made based on the allowable error M, i.e., |Pr - P SET |Is it less than M? If yes, envelope detection is performed; if no, a control signal is output to the millimeter-wave VGA to continuously adjust the transmit power until the receive power is within the allowable error M. S7. An envelope detector is used to perform envelope detection on the millimeter-wave amplitude-modulated signal that is directly connected to the directional coupler to obtain the baseband OOK signal. After passing through the second baseband low-pass filter, it is finally recovered into an Ethernet signal through the electrical port module, thus realizing full-duplex wireless communication of Ethernet millimeter-wave signals.

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