Millimeter wave backscatter communication positioning and identification system for multiple tags

Abstract

The invention relates to the technical field of wireless communication, and discloses a millimeter wave backscatter communication positioning and identification system for multiple tags, which comprises a Chirp signal sending module used for generating and transmitting continuous Chirp signals and receiving signals reflected by customized backscatter tags; and the received signal processing module is used for carrying out demodulation and frequency analysis on the received radar echo signal, determining the distance of the target backscattering tag by measuring the frequency offset of the intermediate frequency signal, and determining the azimuth of the tag through the antenna array of the receiving module. The identity label of the backscattering label is extracted by analyzing the signal intensity; the customized backscattering label is used for adjusting the intensity of the signal reflected back to the radar by changing the reflection state of the backscattering label so as to transmit the identity label of the backscattering label; and the DSSS coding module is used for coding the identity label of the backscattering label so as to increase the signal bandwidth and reduce the signal interference between the labels. According to the method, the customized backscattering tag is matched with the FMCW radar, so that positioning and identification of multiple tags are realized, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a millimeter wave backscatter communication positioning and identification system for multiple tags. Background Art

[0002] With the development of millimeter wave radar technology, the millimeter wave frequency band (30GHz to 300GHz) has been widely used in radar imaging, unmanned driving, intelligent transportation, positioning and recognition due to its high resolution and strong penetration ability. However, in a multi-tag environment, traditional positioning and recognition technology still faces some challenges.

[0003] Signal interference and overlap: In a multi-tag scenario, the signals of multiple tags may interfere with each other, resulting in positioning errors or the inability to accurately distinguish different tags. This is because traditional positioning methods rely on single-frequency signals and are susceptible to multipath effects and co-frequency interference. Complex environment and low precision: Complex environments (such as multipath reflections, obstacles, etc.) will seriously affect the propagation of radar signals, resulting in reduced positioning accuracy. Traditional technologies are usually unable to provide high enough accuracy to meet precise positioning requirements. Challenges in tag identification: In a multi-tag system, each tag needs to have a unique identity (ID) so that the system can distinguish them. Traditional methods rely more on frequency or signal strength, which is susceptible to interference, especially in environments with high-density tags.

[0004] Therefore, a new method is needed to overcome these problems and achieve high-precision multi-tag positioning and accurate tag identification. The present invention proposes to achieve stable and reliable multi-tag positioning and identification through signal strength adjustment and DSSS coding technology by combining millimeter wave backscattering technology with FMCW radar and customized tags. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a millimeter wave backscatter communication positioning and identification system for multiple tags, which can simultaneously realize the precise positioning and identity identification of multiple tags in the same environment.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A millimeter wave backscatter communication positioning and identification system for multiple tags, comprising:

[0008] Chirp signal sending module, used to generate and transmit continuous chirp signals and receive signals reflected by customized backscatter tags. It can measure the distance and locate the target by analyzing the frequency offset of the received intermediate frequency signal.

[0009] The receiving signal processing module is used to demodulate and perform frequency analysis on the received radar echo signal, determine the distance of the target backscatter tag by measuring the frequency offset of the intermediate frequency signal, determine the orientation of the tag through the antenna array of the receiving module, and extract the identity of the backscatter tag by analyzing the signal strength;

[0010] Customized backscatter tags, each with a unique ID. The strength of the signal reflected back to the radar is adjusted by changing the reflection state of the backscatter tag to transmit the ID of the backscatter tag.

[0011] The DSSS encoding module is used to encode the identity of the backscatter tag to increase the signal bandwidth and reduce the signal interference between tags.

[0012] Furthermore, the chirp signal sending module accumulates signal strength in the time domain by transmitting a plurality of consecutive chirp signals, thereby obtaining a signal strength higher than a set reference in the frequency domain, so as to facilitate demodulation of the tag data.

[0013] Furthermore, the received signal processing module includes:

[0014] Distance measurement unit: The radar transmits a continuous frequency modulation wave to the target backscatter tag. After receiving the echo, the radar mixes and down-converts the transmitted signal to obtain an intermediate frequency difference proportional to the distance of the target backscatter tag. The distance measurement unit can calculate the distance of the target backscatter tag based on the known frequency modulation slope and the measured intermediate frequency difference.

[0015] The azimuth and elevation angle measurement unit calculates the phase difference between different antenna units of the same echo through the antenna array on the horizontal plane to obtain the azimuth angle; and calculates the phase difference or performs beamforming processing on the echo signal through the antenna unit or two-dimensional phased array in the vertical direction to obtain the elevation angle;

[0016] The tag ID extraction and decoding unit analyzes the signal strength of each symbol of the intermediate frequency signal, uses a clustering algorithm to distinguish the different bits sent by the tag, and decodes with the same PN sequence to restore the original identity data of the backscattered tag.

[0017] Furthermore, the customized backscatter tag switches between the absorption state and the reflection state by controlling the switch to adjust the amplitude of the signal reflected back to the radar, and processes the identity data of the backscatter tag through DSSS coding to improve the anti-interference capability between backscatter tags.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are:

[0019] Simultaneous positioning and identification of multiple tags: Through the difference in signal strength reflected by different tags and DSSS coding, multiple tags can be effectively distinguished to achieve simultaneous positioning and identification.

[0020] High-precision positioning: By using the intermediate frequency signal and frequency change analysis of FMCW radar, high-precision positioning can be achieved, especially in the millimeter wave frequency band, with higher accuracy.

[0021] Strong anti-interference ability: DSSS coding technology improves the anti-interference ability of tag signals and can effectively avoid signal interference in multi-tag environments.

[0022] Wide scope of application: This technology can be widely used in the fields of Internet of Things, intelligent manufacturing, warehouse management, asset tracking, etc., and has good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the system architecture of the present invention;

[0024] Figure 2 Schematic diagram of symbols sent by FMCW radar. DETAILED DESCRIPTION

[0025] A preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0026] 1. System architecture overview:

[0027] like Figure 1 As shown, the system of the present invention is mainly composed of the following parts:

[0028] Chirp signal sending module: used to generate and transmit continuous chirp signals and receive the signals reflected by the tag. The system can measure the distance and locate the target by analyzing the frequency offset of the received intermediate frequency signal.

[0029] Received signal processing module: After receiving the radar echo signal, it demodulates and performs frequency analysis on it. By processing the signal strength and frequency changes, it accurately estimates the location of the tag and extracts the tag's identity (ID) information.

[0030] Customized backscatter tags: Each tag has a unique identity and can recognize radar by changing its reflective state (absorbing or reflecting radar signals). The on / off state of the tag directly affects the strength of the echo signal, thereby transmitting the tag ID.

[0031] DSSS encoding module: In order to solve the interference problem between multiple tags, this system increases the signal bandwidth by DSSS encoding the tag ID, thereby effectively reducing the signal interference between tags and improving the recognition accuracy.

[0032] 2. The present invention is applicable to the following target application scenarios:

[0033] (1) Internet of Things (IoT) and Smart Home: With the popularity of smart home devices, the number of IoT devices is increasing, and how to accurately locate and identify devices has become the key. Traditional wireless communication and positioning technologies may face signal interference and accuracy issues.

[0034] (2) Industrial Automation and Logistics Management: In large-scale warehousing and production environments, it is necessary to accurately track the location of items in order to optimize warehouse management, production processes, and logistics scheduling.

[0035] (3) Asset management and anti-theft system: Asset management and anti-theft are important issues in large enterprises, shopping malls, airports, etc. Traditional barcode and RFID technologies face certain distance limitations and signal interference issues.

[0036] (4) Intelligent transportation and vehicle positioning: Intelligent transportation systems (ITS) need to accurately locate and identify vehicles, transportation facilities and other targets in order to conduct flow monitoring, autonomous driving navigation and traffic safety management.

[0037] The technical solution in the present invention can play a role in the above application scenarios.

[0038] 3. Module design details

[0039] The entire system is mainly divided into two parts, namely the FMCW module and the tag module. The FMCW module is responsible for sending chirp signals and processing intermediate frequency signals, and the tag module is responsible for adjusting switches and DSSS encoding.

[0040] (1) Chirp signal transmission

[0041] like Figure 2 As shown, the FMCW radar generates a frequency modulated chirp signal, usually a linear frequency modulated signal, whose frequency increases over time. The signal frequency gradually increases from a low value to a high value, and then the process is repeated. In previous work, a chirp signal represents a symbol. However, we found that multiple consecutive chirp signals can result in more accumulation in the time domain, which is reflected in the frequency domain. The frequency has a higher signal strength. The present invention hopes to improve the signal strength, because a greater signal strength can produce more obvious intensity changes, which is beneficial to demodulating the tag data.

[0042] (2) Received signal processing module

[0043] This module is responsible for obtaining and analyzing the measurement parameters of the signal received by the radar and demodulating the tag data. Its main functions are as follows:

[0044] Tag positioning: Distance: The radar transmits a continuous frequency modulated wave to the target. After receiving the echo, the radar mixes and down-converts the transmitted signal to obtain an intermediate frequency difference proportional to the target distance. According to the known frequency modulation slope and the measured intermediate frequency difference, the target distance can be calculated; Azimuth: Through the antenna array on the horizontal plane, the phase difference between the same echo and the antenna units is solved to obtain the azimuth; Elevation: Through the antenna unit layout in the vertical direction or the two-dimensional phased array, the echo signal is subjected to phase difference solution or beamforming processing to obtain the elevation angle.

[0045] Tag ID extraction and decoding: By analyzing the signal strength of each symbol of the intermediate frequency signal, a clustering algorithm is used to obtain two categories. These two types of data represent two different bits sent by the tag, so that the data reflected by the tag can be obtained. Then, by decoding with the same PN sequence, the original ID data of the tag is restored. Since the spread spectrum signal can effectively resist co-frequency interference, the system can efficiently distinguish different tags. By analyzing the amplitude change of the tag echo and the DSSS coding information, the system can successfully extract the tag ID to ensure accurate tag identification.

[0046] (3) Customized backscatter tags

[0047] Backscatter tags are another core component of this system. The tag is designed to respond to FMCW radar signals and return its ID information to the radar. The tag's workflow is as follows:

[0048] Signal reception and reflection: The tag receives the chirp signal from the FMCW radar and decides whether to reflect the signal based on the tag's internal control mechanism (such as switch adjustment). The tag transmits its own ID based on the strength of the reflected signal.

[0049] Tag state adjustment: The tag switches between the "absorption" and "reflection" states by controlling the switch. When the tag reflects the signal, it introduces a change in the signal amplitude, allowing the radar to identify the tag's ID.

[0050] (4) DSSS coding: The ID data in the tag will be processed by DSSS coding, which can effectively expand the signal bandwidth and improve the anti-interference ability between tags. DSSS coding modulates the tag ID with a pseudo-random sequence so that the signal can be correctly decoded and avoid interference.

[0051] Example

[0052] As an example, the technical solution of the present invention is applied to the positioning of drones and robots. In this application scenario, drones and automated robots are widely used in modern military, logistics distribution, inspection and other fields. Accurate real-time positioning and identification are essential for their navigation and task execution. Using multi-label millimeter-wave backscattering technology, multiple drones or robots can be accurately positioned and identified. In the scenario where multiple drones are operating at the same time, this system can avoid signal conflicts and ensure accurate identification of the status of each drone. It can be used in related scenarios such as drone group positioning and identification, robot cluster collaboration, accurate path planning and task allocation.

[0053] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0054] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A millimeter wave backscatter communication positioning and identification system for multiple tags, characterized in that: include: Chirp signal sending module, used to generate and transmit continuous chirp signals and receive signals reflected by customized backscatter tags. It can measure the distance and locate the target by analyzing the frequency offset of the received intermediate frequency signal. The receiving signal processing module is used to demodulate and perform frequency analysis on the received radar echo signal, determine the distance of the target backscatter tag by measuring the frequency offset of the intermediate frequency signal, determine the orientation of the tag through the antenna array of the receiving module, and extract the identity of the backscatter tag by analyzing the signal strength; Customized backscatter tags, each with a unique ID. The strength of the signal reflected back to the radar is adjusted by changing the reflection state of the backscatter tag to transmit the ID of the backscatter tag. The DSSS encoding module is used to encode the identity of the backscatter tag to increase the signal bandwidth and reduce the signal interference between tags.

2. The millimeter wave backscatter communication positioning and identification system for multiple tags according to claim 1 is characterized in that: The chirp signal sending module accumulates signal strength in the time domain by transmitting a plurality of consecutive chirp signals, thereby obtaining a signal strength higher than a set reference in the frequency domain, so as to facilitate demodulation of tag data.

3. The millimeter wave backscatter communication positioning and identification system for multiple tags according to claim 1 is characterized in that: The received signal processing module comprises: Distance measurement unit: The radar transmits a continuous frequency modulation wave to the target backscatter tag. After receiving the echo, the radar mixes and down-converts the transmitted signal to obtain an intermediate frequency difference proportional to the distance of the target backscatter tag. The distance measurement unit can calculate the distance of the target backscatter tag based on the known frequency modulation slope and the measured intermediate frequency difference. The azimuth and elevation angle measurement unit calculates the phase difference between different antenna units of the same echo through the antenna array on the horizontal plane to obtain the azimuth angle; and calculates the phase difference or performs beamforming processing on the echo signal through the antenna unit or two-dimensional phased array in the vertical direction to obtain the elevation angle; The tag ID extraction and decoding unit analyzes the signal strength of each symbol of the intermediate frequency signal, uses a clustering algorithm to distinguish the different bits sent by the tag, and decodes with the same PN sequence to restore the original identity data of the backscattered tag.

4. The millimeter wave backscatter communication positioning and identification system for multiple tags according to claim 1, characterized in that: The customized backscatter tag switches between the absorption state and the reflection state by controlling the switch to adjust the amplitude of the signal reflected back to the radar, and processes the identity data of the backscatter tag through DSSS coding to improve the anti-interference capability between backscatter tags.

Images