A communication method between a mobile phone user and a millimeter wave radar based on motor vibration

Abstract

The present invention belongs to the technical field of Internet of Things and synaesthesia integration, and discloses a communication method between a mobile phone user and a millimeter wave radar based on motor vibration. The sender first designs a vibration mode using pulse width and amplitude modulation technology, and then controls the smartphone motor to generate a corresponding vibration signal. The receiving millimeter wave radar continuously sends millimeter wave signals and analyzes the received reflected signals. According to the vibration characteristics of the mobile phone motor, the target vibration object, that is, the sender, is locked, and the vibration signal is then restored and decoded, and finally the information or instructions transmitted by the sender are obtained. The present invention establishes a channel between the mobile phone user and the millimeter wave radar without any hardware modification, thereby realizing the synaesthesia integration of commercial millimeter wave radars and enriching the application scenarios of millimeter wave radars.

Description

Technical Field

[0001] The present invention belongs to the technical field of Internet of Things and synaesthesia integration, and specifically relates to a communication method between a mobile phone user and a millimeter wave radar based on motor vibration. Background Art

[0002] With the advent of the Internet of Things era, the number of wireless communication devices has increased dramatically, and the demand for spectrum resources has increased day by day, prompting wireless communication technology to gradually develop towards the millimeter wave frequency band to meet the needs of low-latency communication and massive data transmission. The fifth-generation mobile communication technology has adopted an architecture that combines medium and low frequency bands with millimeter wave bands, accelerating the transformation of social economy towards digitalization, networking, and intelligence.

[0003] At the same time, the field of wireless sensing is also evolving. Millimeter-wave radar, as a sensing method with small size, high spatial resolution and all-weather operation, has attracted much attention. Millimeter-wave radar has been widely used in the fields of vehicle-mounted, transportation, security, industrial monitoring, etc. Driven by market demand and national policies, the underlying technology of millimeter-wave radar has achieved breakthroughs in China and is becoming increasingly mature.

[0004] As wireless communications and wireless sensing develop towards the millimeter wave frequency band, frequency band competition and interference have become one of the urgent problems to be solved, giving rise to the idea of ​​communication and perception integration. Synaesthesia integration aims to integrate the two functions of communication and perception on the same hardware system, improve resource utilization, and achieve deep integration and mutual benefit between communication and perception. Synaesthesia integration has been listed as an important topic in the field of information and electronic engineering, opening a new chapter for the integrated application of wireless technologies in the future. Giving millimeter wave radar communication capabilities has three major advantages: improving resource utilization, enriching information dimensions, and opening up innovative applications. This concept has brought a new revolution to the field of wireless communications and wireless sensing, but current research mainly focuses on synaesthesia integration for communication systems, and synaesthesia integration solutions for perception systems are not yet mature. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a communication method between a mobile phone user and a millimeter-wave radar based on motor vibration, which uses the motor vibration of the smart phone carried by the user to transmit information or instructions. The millimeter-wave radar senses and decodes the vibration to receive user information and respond to user requests, thereby completing the perception of the target user and the reception of user information. The present invention takes millimeter-wave radar as the research object, and is committed to giving millimeter-wave radar communication capabilities, promoting the integrated development of synaesthesia of wireless sensing systems, and meeting the needs of various application scenarios in the future.

[0006] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0007] The present invention is a communication method between a mobile phone user and a millimeter wave radar based on motor vibration, which specifically includes the following steps:

[0008] Step 1, vibration pattern design: The sender designs the vibration pattern using pulse width and amplitude modulation technology;

[0009] Step 2, vibration signal generation: the sender controls the motor of the mobile device to generate the designed vibration signal;

[0010] Step 3, vibration target identification: The receiver sends a millimeter wave signal and analyzes the reflected signal of the target object in the environment, detects the surrounding objects by calculating the range Doppler spectrum, and analyzes the reflected signal of each candidate target object to confirm the target sender, that is, the object transmitting the designed vibration signal;

[0011] Step 4: Vibration signal recovery: Use a bandpass filter to filter out noise and recover the vibration signal of the target sender. The targets are divided into single targets and multiple targets.

[0012] Step 5: Vibration signal decoding: Decode the vibration pattern of each single target and each multi-target to accurately receive the information or instructions transmitted by the target user.

[0013] A further improvement of the present invention lies in that: in step 1, the sender uses pulse width and amplitude modulation technology to design a vibration pattern, specifically: using pulse width and amplitude modulation technology, for a data symbol with a duration of T seconds, it is represented as M+N bits, wherein M bits are used to control the pulse width, i.e., the vibration time, and N bits are used to control the pulse amplitude. By adjusting the pulse width and amplitude of the sender's motor vibration, the vibration pattern design is achieved, and more information can be transmitted in the same signal, thereby improving the communication rate.

[0014] A further improvement of the present invention is that in step 2, according to the characteristics of pulse width and amplitude modulation technology and the characteristics of the application program interface provided by the current mobile phone, two parameters are used to control the vibration motor: the vibration time T in milliseconds; vib and the vibration amplitude A in the range [0,255] vib , a preamble is added at the beginning of each data frame to enable the receiver to identify the parameter value related to the transmitted data symbol, wherein the preamble is a preamble of three symbols, and its vibration amplitude is 20% of the maximum amplitude, 90% of the maximum amplitude and non-vibration state respectively.

[0015] A further improvement of the present invention is that the step 3 specifically includes the following steps:

[0016] Step 3.1, range Doppler spectrum acquisition: perform a range fast Fourier transform operation on the received reflection signal of the candidate target object, decompose the reflection signal of the target object in terms of distance and obtain a range fast Fourier transform spectrum, perform a Doppler fast Fourier transform, decompose the signal in terms of speed, and obtain a range Doppler spectrum;

[0017] Step 3.2, object detection based on constant false alarm algorithm: Use the constant false alarm detection algorithm to search for bright spots in the range Doppler spectrum obtained in step 3.1, which are candidate objects. If the value of a square exceeds a threshold, it is considered that there is a candidate object at that location; specifically, the constant false alarm detection uses an adaptive threshold to detect objects by tracking background noise. Based on experience, the false alarm rate is set to 10 -5 At the same time, a moving window is used to merge adjacent peaks in candidate object detection.

[0018] Step 3.3, candidate object position extraction: use the phase difference of the signals received by multiple antennas to calculate the arrival angle θ:

[0019] θ=sin -1 (λω / 2πd A )

[0020] Among them, d A represents the spacing between the receiving antennas, μ represents the phase difference between the two antennas, and λ represents the wavelength;

[0021] Assuming the distance between a candidate object and the millimeter-wave radar is r, and the arrival angle is θ, the candidate object position L(x,z) is calculated as:

[0022] x=rsin(θ)

[0023] z=rcos(θ)

[0024] Step 3.4, vibration target identification: After detecting the candidate objects around the millimeter-wave radar, analyze the phase value of the reflected signal of each candidate object. Compared with the stationary object, the vibrating target has a larger fluctuation in the phase value, and the vibrating target presents a peak in the vibration frequency range of 100Hz to 300Hz of the mobile phone, thereby determining whether the candidate object is the transmitter that sends the vibration signal, that is, the vibrating mobile phone.

[0025] A further improvement of the present invention is that in step 4, the vibration signal recovery of a single target specifically includes the following steps:

[0026] Step 4.1.1: Build a millimeter-wave based transmitter vibration model: The millimeter-wave radar is placed at the origin of the coordinate system, and the initial position of the vibration source is S 0 (x 0 ,z 0 ), the initial distance from the millimeter wave radar is R0 , when the vibration source vibrates, the vibration source motor follows simple harmonic motion and produces a small displacement δ(t) that varies with time:

[0027] δ(t)=A cos(2πf v t)

[0028] Where A represents the vibration amplitude, f v Indicates the vibration frequency;

[0029] Since there is a misalignment β between the vibration direction of the transmitter and the sensing direction of the millimeter-wave radar, the actual vibration displacement δ′(t) sensed is the projection of the motor vibration displacement along the radar sensing direction, that is, δ′(t) = cosβ·δ(t). The distance R(t) of the vibration source sensed by the millimeter-wave radar is R 0 +δ′(t), the received millimeter wave signal s(t) from the vibration source is expressed as:

[0030]

[0031] Where α represents the path loss, K represents the chirp signal slope, and j represents the imaginary part of the complex signal;

[0032] Step 4.1.2: Perform distance FFT operation on the received millimeter wave signal s(t) to obtain the reflected signal S at the target distance. r (t):

[0033]

[0034] The phase value of the signal from the target distance r is expressed as:

[0035]

[0036] Among them, R 0 represents the initial distance of the sender relative to the millimeter-wave radar, and β represents the angle between the vibration direction of the sender and the sensing direction of the millimeter-wave radar;

[0037] Therefore, the phase value φ of the signal r (t) can reflect the vibration of the mobile phone, and its vibration displacement δ(t) is expressed as:

[0038]

[0039] Among them, unwrap represents the phase unwrapping operation;

[0040] Step 4.1.3: Based on the transmitter vibration model, a bandpass filter is used to extract the target vibration signal, and the DC component and noise are filtered out. The filtered vibration signal Y(t) is expressed as:

[0041]

[0042] According to the range of the vibration frequency of the mobile phone, the lower limit frequency and the upper limit frequency of the bandpass filter are set to 100 Hz and 300 Hz respectively, covering the vibration frequencies of most mobile phone vibration motors.

[0043] A further improvement of the present invention is that in step 4, when multiple targets communicate concurrently, multiple targets are separated in three dimensions of distance, angle, and vibration frequency, and then the vibration signal of each target is restored, which specifically includes the following steps:

[0044] Step 4.2.1, separate signals in the distance dimension: when multiple targets send vibration signals in different distance ranges, and there is only one vibration target in each distance range, directly use the distance fast Fourier transform to separate the targets in different distance ranges;

[0045] Step 4.2.2, separate the signals in the angle dimension: When two vibrating objects are at the same distance relative to the radar, use beamforming technology to focus on targets in different directions to separate them;

[0046] Step 4.2.3: Separate signals based on vibration frequency: When two targets cannot be separated in terms of distance or angle, the diversity of the vibration frequency of the vibration source is used to further separate multiple objects.

[0047] A further improvement of the present invention is that: step 5 decodes the vibration pattern of the target and accurately receives the information or instructions transmitted by the target user, specifically: the receiver first performs preamble code detection for synchronization and signal strength estimation, then segments the symbols and then demodulates them to extract data bits.

[0048] A further improvement of the present invention is that preamble detection means that the preamble is used to locate the beginning of the data symbol, the receiver uses a cross-correlation method to accurately locate the preamble, and performs channel estimation before extracting the symbol.

[0049] A further improvement of the present invention is that segmenting the symbol means that after completing the preamble detection, the receiver uses a pre-known fixed pulse length to segment the symbol after the preamble, and after channel estimation, the receiver determines the amplitude and width information in each symbol, restores the original data bit, and obtains the information or instruction transmitted by the sender.

[0050] The beneficial effects of the present invention are as follows: compared with the existing beam design driven and intelligent surface driven millimeter wave radar interawareness integrated solutions, the perception driven millimeter wave radar interawareness integrated solution proposed by the present invention has four major characteristics: good versatility, strong compatibility, easy implementation, and low cost, specifically:

[0051] (1) Good versatility: The integrated solution of the present invention utilizes the universal and controllable mechanical vibration of mobile devices to transmit various user instructions to the millimeter wave radar. Multiple vibration modulation schemes realize flexible information transmission and meet various application scenarios and user needs.

[0052] (2) Strong compatibility: The integrated solution of the present invention utilizes the powerful sensing capability of millimeter-wave radar to capture vibration signals carrying user instructions and complete information reception. It is seamlessly compatible with existing commercial millimeter-wave radars without the need for any hardware modification.

[0053] (3) Easy to implement: The integrated solution of the present invention uses software programming to accurately control mechanical vibration and transmit various user commands. When the millimeter-wave radar senses the vibration signal carrying the user command, it can receive the user command through signal processing and software decoding. The entire process is completely dependent on software control and is easy to implement and deploy.

[0054] (4) Low cost: The integrated solution of the present invention utilizes the vibration of a universal mobile device to transmit user instructions to the millimeter-wave radar and is compatible with existing commercial millimeter-wave radars. Compared with other solutions, the integrated solution of the present invention does not require any hardware upgrades or modifications, and does not require the introduction of customized external components, thus having the advantage of low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a flow chart of the communication method of the present invention.

[0056] Figure 2 It is a flow chart of the communication system between the user's mobile phone and the millimeter wave radar in the motor vibration embodiment of the present invention.

[0057] Figure 3 Schematic diagram of a vibration model in an embodiment of the present invention.

[0058] Figure 4 1 is a diagram showing a sample of pulse width and amplitude modulation technology symbols in an embodiment of the present invention.

[0059] Figure 5 It is the mobile phone vibration symbol restored by the millimeter wave radar in the embodiment of the present invention. DETAILED DESCRIPTION

[0060] The following will disclose the embodiments of the present invention with drawings. For the purpose of clear description, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present invention. That is to say, in some embodiments of the present invention, these practical details are not necessary.

[0061] like Figure 1-2As shown, the present invention is a communication method between a mobile phone user and a millimeter wave radar based on motor vibration, characterized in that the communication method specifically includes the following steps:

[0062] Step 1, vibration pattern design: The sender, i.e., the mobile phone user, designs the vibration pattern using pulse width and amplitude modulation technology. Specifically, using pulse width and amplitude modulation technology, for a data symbol with a duration of T seconds, it is represented as M+N data bits, where M bits are used to control the pulse width, i.e., the vibration time, and N bits are used to control the pulse amplitude. By adjusting the pulse width and amplitude of the motor vibration of the sender, i.e., the mobile phone user, the vibration pattern design is achieved, which can transmit more information in the same signal, thereby increasing the communication rate.

[0063] like Figure 4 As shown, a data symbol with a duration of T seconds can represent M+N bits. M bits correspond to 2 M The vibration motor vibration time percentage of each level, N bits correspond to 2 N The vibration amplitude of each level. Figure 4 This is an example of M=2, N=2, then each data symbol contains four bits. Among them, the vibration motor vibration time percentage of each symbol is taken into four levels, namely 25%, 50%, 75%, and 100%, respectively, representing the first two bits 00, 01, 10, and 11, respectively, as shown in the horizontal axis in the figure. The vibration amplitude is divided into four levels: A1, A2, A3, and A4, representing the last two bits 00, 01, 10, and 11, respectively, as shown in the vertical axis in the figure. Four bits can together represent a data symbol with a duration of T seconds.

[0064] Step 2: Vibration signal generation: The sender controls the motor of the mobile device to generate the designed vibration signal. According to the characteristics of pulse width and amplitude modulation technology and the characteristics of the application program interface provided by the current mobile phone, two parameters are used to control the vibration motor: the vibration time T in milliseconds vib and the vibration amplitude A in the range [0,255] vib , a preamble is added at the beginning of each data frame to enable the receiver to identify the parameter value related to the transmitted data symbol, wherein the preamble is a preamble of three symbols, and its vibration amplitude is 20% of the maximum amplitude, 90% of the maximum amplitude and non-vibration state respectively.

[0065] Step 3, vibration target identification: The receiver, i.e., the millimeter wave radar, sends millimeter wave signals and analyzes the reflected signals of the target objects in the environment, detects the surrounding objects by calculating the range Doppler spectrum, and analyzes the reflected signals of each candidate target object to confirm the target sender, i.e., the object transmitting the designed vibration signal;

[0066] The specific steps include:

[0067] Step 3.1, range Doppler spectrum acquisition: perform a range fast Fourier transform operation on the received reflection signal of the candidate target object, decompose the reflection signal of the target object in terms of distance and obtain a range fast Fourier transform spectrum, perform a Doppler fast Fourier transform, decompose the signal in terms of speed, and obtain a range Doppler spectrum;

[0068] Step 3.2, object detection based on constant false alarm algorithm: Use the constant false alarm detection algorithm to search for bright spots in the range Doppler spectrum obtained in step 3.1, which are candidate objects. If the value of a square exceeds a threshold, it is considered that there is a candidate object at that location; specifically, the constant false alarm detection uses an adaptive threshold to detect objects by tracking background noise. Based on experience, the false alarm rate is set to 10 -5 At the same time, a moving window is used to merge adjacent peaks in candidate object detection.

[0069] Step 3.3, candidate object position extraction: use the phase difference of the signals received by multiple antennas to calculate the arrival angle θ:

[0070] θ=sin -1 (λω / 2πd A )

[0071] Among them, d A represents the spacing between the receiving antennas, ω represents the phase difference between the two antennas, and λ represents the wavelength;

[0072] Assuming the distance between a candidate object and the millimeter-wave radar is r, and the arrival angle is θ, the candidate object position L(x,z) is calculated as:

[0073] x = rsin(θ);

[0074] z = rcos(θ);

[0075] Step 3.4, vibration target identification: After detecting the candidate objects around the millimeter-wave radar, analyze the phase value of the reflected signal of each candidate object. Compared with the stationary object, the vibrating target has a larger fluctuation in the phase value, and the vibrating target presents a peak in the vibration frequency range of 100Hz to 300Hz of the mobile phone, thereby determining whether the candidate object is the transmitter that sends the vibration signal, that is, the vibrating mobile phone.

[0076] Step 4: Vibration signal recovery: Use a bandpass filter to filter out noise and recover the vibration signal of the target sender, which can be divided into single-target and multi-target cases.

[0077] The vibration signal recovery of a single target specifically includes the following steps:

[0078] Step 4.1.1: Build a millimeter wave based transmitter, i.e., mobile phone vibration model: the millimeter wave radar is placed at the origin of the coordinate system, and the initial position of the vibration source, i.e., the mobile phone, is S 0 (x 0 ,z 0 ), the initial distance from the millimeter wave radar is R 0 , when the vibration source, i.e. the mobile phone, vibrates, the vibration source, i.e. the mobile phone motor, follows simple harmonic motion and produces a small displacement δ(t) that varies with time:

[0079] δ(t)=A cos(2πf v t)

[0080] Where A represents the vibration amplitude, f v Indicates the vibration frequency;

[0081] like Figure 3 As shown, when the smartphone vibrates, it will move along Figure 3 The vibration direction indicated by the solid red arrow produces a small displacement δ(t) that changes with time. The sensing direction of the millimeter-wave radar is the direction of the line connecting the millimeter-wave radar and the smartphone, which is the direction indicated by the hollow red arrow.

[0082] Since there is a misalignment β between the vibration direction of the sender, i.e., the mobile phone, and the sensing direction of the millimeter-wave radar, the actual vibration displacement δ′(t) sensed is the projection of the motor vibration displacement along the radar sensing direction, i.e., δ′(t) = cosβ·δ(t). The distance R(t) from the vibration source, i.e., the mobile phone, sensed by the millimeter-wave radar is R 0 +δ′(t), the received millimeter wave signal s(t) from the vibration source, i.e. the mobile phone, is expressed as:

[0083]

[0084] Where α represents the path loss, K represents the chirp signal slope, and j represents the imaginary part of the complex signal;

[0085] Step 4.1.2: Perform a distance FFT operation on the received millimeter wave signal s(t) to obtain the reflected signal S at the target distance. r (t):

[0086]

[0087] The phase value of the signal from the target distance r is expressed as:

[0088]

[0089] Among them, R 0 represents the initial distance of the sender relative to the millimeter-wave radar, and β represents the angle between the vibration direction of the sender and the sensing direction of the millimeter-wave radar;

[0090] Therefore, the phase value φ of the signal r (t) can reflect the vibration of the mobile phone, and its vibration displacement δ(t) is expressed as:

[0091]

[0092] Among them, unwrap represents the phase unwrapping operation;

[0093] Step 4.1.3, based on the vibration model of the sender, i.e. the mobile phone, a bandpass filter is used to extract the target vibration signal, while filtering out the DC component and noise. The filtered vibration signal Y(t) is expressed as:

[0094]

[0095] According to the range of the vibration frequency of the mobile phone, the lower limit frequency and the upper limit frequency of the bandpass filter are set to 100 Hz and 300 Hz respectively, covering the vibration frequencies of most mobile phone vibration motors.

[0096] like Figure 5 As shown in the figure, a sample of the recovered vibration signal in a single target scenario is shown. After passing through the bandpass filter, the recovered vibration signal contains four symbols. The vibration motor vibration time percentage of each symbol has four levels, namely 25%, 50%, 75%, and 100%, as shown in the horizontal axis of the figure. The vibration amplitude is divided into four levels: A1, A2, A3, and A4, as shown in the vertical axis of the figure. The recovered vibration signal is Figure 4 The vibration signal sent by the sender is consistent, indicating that the vibration signal is accurately recovered.

[0097] In practice, multiple mobile phones may communicate with the millimeter wave radar at the same time, causing interference and collision on the receiving end. Therefore, when multiple targets communicate concurrently, multiple targets are separated in three dimensions: distance, angle, and vibration frequency, and then the vibration signal of each target is restored. The specific steps include:

[0098] Step 4.2.1, Separate signals in the distance dimension: When multiple targets send vibration signals in different distance ranges, and there is only one vibration target in each distance range, directly use the distance fast Fourier transform to separate the targets in different distance ranges; use the short-time Fourier transform to generate the vibration spectrum and vibration level to show the characteristic differences of the vibration signals in different ranges. By observing the vibration spectrum and vibration level, we can clearly see the different vibration modes of the vibration signals in different distance ranges, thereby achieving effective separation of targets in the distance range.

[0099] Step 4.2.2, separate the signal in the angular dimension: When two vibrating objects are at the same distance relative to the radar, use beamforming technology to focus on targets in different directions to separate them; by adjusting the beam pointing angle and utilizing the synergy of multiple receiving antennas, the signal-to-noise ratio of the vibration signal can be improved and the multipath effect can be mitigated, thereby achieving more accurate target separation and vibration signal extraction.

[0100] Step 4.2.3, Separate signals based on vibration frequency: When two targets cannot be separated in terms of distance or angle, the diversity of the vibration source, i.e., the vibration frequency of the mobile phone, is used to further separate multiple objects. By extracting the vibration signal corresponding to the vibration frequency, the expected vibration pattern can be observed. This shows that even when the two close objects cannot be separated in terms of distance or angle, the vibration frequency can be used as another dimension to resolve their conflict, thereby achieving effective separation of multiple targets.

[0101] Step 5, vibration signal decoding: Decode the vibration pattern of each single target and each multi-target to accurately receive the information or instructions transmitted by the target user. Specifically, the receiver first performs preamble code detection for synchronization and signal strength estimation, then segments the symbols and then demodulates them to extract the data bits.

[0102] Preamble detection means that the preamble is used to locate the beginning of the data symbol. The receiver uses the cross-correlation method to accurately locate the preamble and performs channel estimation before extracting the symbol.

[0103] Symbol segmentation means that after completing the preamble code detection, the receiver uses a pre-known fixed pulse length to segment the symbols after the preamble code. After channel estimation, the receiver determines the amplitude and width information in each symbol, restores the original data bits, and obtains the information or instructions transmitted by the sender.

[0104] The present invention utilizes millimeter-wave radar sensing technology to sense the motor vibration pattern carrying user instructions in a contactless manner, thereby allowing the millimeter-wave radar to simultaneously receive information or instructions transmitted by the user to the millimeter-wave radar using motor vibration while sensing the user, thereby realizing the inter-sensory integration of the millimeter-wave radar.

[0105] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A communication method between a mobile phone user and a millimeter wave radar based on motor vibration, characterized in that: The communication method specifically comprises the following steps: Step 1, vibration pattern design: The sender designs the vibration pattern using pulse width and amplitude modulation technology; Step 2, vibration signal generation: the sender controls the motor of the mobile device to generate the designed vibration signal; Step 3, vibration target identification: The receiver sends a millimeter wave signal and analyzes the reflected signal of the target object in the environment, detects the surrounding objects by calculating the range Doppler spectrum, and analyzes the reflected signal of each candidate target object to confirm the target sender, that is, the object transmitting the designed vibration signal; Step 4: Vibration signal recovery: Use a bandpass filter to filter out noise and recover the vibration signal of the target sender. The targets are divided into single targets and multiple targets. Step 5: Vibration signal decoding: Decode the vibration pattern of each single target and each multi-target to accurately receive the information or instructions transmitted by the target user, where: In step 2, according to the characteristics of pulse width and amplitude modulation technology and the characteristics of the application program interface provided by the current mobile phone, two parameters are used to control the vibration motor: the vibration time T in milliseconds; vib and the vibration amplitude A in the range [0,255] vib , adding a preamble code at the beginning of each data frame so that the receiving party can identify the parameter value related to the transmitted data symbol, wherein the preamble code is a preamble code of three symbols, and the vibration amplitudes thereof are respectively 20% of the maximum amplitude, 90% of the maximum amplitude and a non-vibration state; The step 1 in which the sender uses pulse width and amplitude modulation technology to design the vibration mode is specifically as follows: using pulse width and amplitude modulation technology, for a data symbol with a duration of T seconds, it is represented as M+N bits, wherein M bits are used to control the pulse width, i.e., the vibration time, and N bits are used to control the pulse amplitude, and the vibration mode design is achieved by adjusting the pulse width and amplitude of the sender's motor vibration; The step 3 specifically comprises the following steps: Step 3.1, range Doppler spectrum acquisition: perform a range fast Fourier transform operation on the received reflection signal of the candidate target object, decompose the reflection signal of the target object in terms of distance and obtain a range fast Fourier transform spectrum, perform a Doppler fast Fourier transform, decompose the signal in terms of speed, and obtain a range Doppler spectrum; Step 3.2, object detection based on constant false alarm algorithm: Use the constant false alarm detection algorithm to search for bright spots in the range Doppler spectrum obtained in step 3.1, i.e., candidate objects. If the value of a square exceeds a threshold, it is considered that there is a candidate object in the square; Step 3.3, candidate object position extraction: use the phase difference of the signals received by multiple antennas to calculate the arrival angle θ: θ=sin -1 (λ / 2πd) A ) Among them, d A represents the spacing between the receiving antennas, ω represents the phase difference between the two antennas, and λ represents the wavelength; Assuming the distance between a candidate object and the millimeter-wave radar is r, and the arrival angle is θ, the candidate object position L(x,z) is calculated as: x = rsin(θ); z = rcos(θ); Step 3.4, vibration target identification: After detecting the candidate objects around the millimeter wave radar, analyze the phase value of the reflected signal of each candidate object. Compared with the stationary object, the vibration target has a larger fluctuation in the phase value, and the vibration target presents a peak in the vibration frequency range of 100Hz to 300Hz of the mobile phone, thereby determining whether the candidate object is the transmitter that sends the vibration signal, that is, the vibrating mobile phone; In step 4, the vibration signal recovery of a single target specifically includes the following steps: Step 4.1.

1. Construct a millimeter-wave based transmitter vibration model: the millimeter-wave radar is placed at the origin of the coordinate system, the initial position of the vibration source is S0 (x0, z0), and the initial distance from the millimeter-wave radar is R0. When the vibration source vibrates, the vibration source motor produces a displacement δ(t) that varies with time: δ(t)=A cos(2πf v t) Where A represents the vibration amplitude, f v Indicates the vibration frequency; Since there is a misalignment β between the vibration direction of the transmitter and the sensing direction of the millimeter-wave radar, the actual vibration displacement δ ′ (t) is the projection of the motor vibration displacement along the radar sensing direction, i.e., δ ′ (t) = cosβ·δ(t), the distance R(t) of the vibration source sensed by the millimeter wave radar is R0+δ ′ (t), the received millimeter wave signal s(t) from the vibration source is expressed as: Where α represents the path loss, K represents the chirp signal slope, and j represents the imaginary part of the complex signal; Step 4.1.2: Perform distance FFT operation on the received millimeter wave signal s(t) to obtain the reflected signal S at the target distance r. r (t): The phase value of the signal from the target distance r is expressed as: Among them, R0 represents the initial distance of the sender relative to the millimeter-wave radar, and β represents the angle between the vibration direction of the sender and the sensing direction of the millimeter-wave radar; Therefore, the phase value φ of the signal r (t) can reflect the vibration of the mobile phone, and its vibration displacement δ(t) is expressed as: Among them, unwrap represents the phase unwrapping operation; Step 4.1.3: Based on the transmitter vibration model, a bandpass filter is used to extract the target vibration signal, and the DC component and noise are filtered out. The filtered vibration signal Y(t) is expressed as: According to the range of the vibration frequency of the mobile phone, the lower limit frequency and the upper limit frequency of the bandpass filter are set to 100 Hz and 300 Hz respectively.

2. The method for communication between a mobile phone user and a millimeter wave radar based on motor vibration according to claim 1, characterized in that: The step 5 decodes the vibration pattern of the target and accurately receives the information or instructions transmitted by the target user. Specifically, the receiver first performs preamble code detection for synchronization and signal strength estimation, then segments the symbols and then demodulates them to extract data bits.

3. The method for communication between a mobile phone user and a millimeter wave radar based on motor vibration according to claim 2, characterized in that: Preamble detection means that the preamble is used to locate the beginning of the data symbol. The receiver uses the cross-correlation method to accurately locate the preamble and performs channel estimation before extracting the symbol.

4. The method for communication between a mobile phone user and a millimeter wave radar based on motor vibration according to claim 2, characterized in that: Symbol segmentation means that after completing the preamble code detection, the receiver uses a pre-known fixed pulse length to segment the symbols after the preamble code. After channel estimation, the receiver determines the amplitude and width information in each symbol, restores the original data bits, and obtains the information or instructions transmitted by the sender.

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