A system based on a passive node tag chip compatible with long-distance communication

Abstract

The present invention discloses a system based on a passive node tag chip compatible with long-distance communication, relating to the technical field of wireless communication. The system solves the problems in the prior art of complex device connection, high cost, and the fact that the generation of digital square waves also requires a crystal oscillator drive on an MCU, making it difficult to popularize the system on a large scale in the passive Internet of Things. The chip comprises: an antenna for acquiring an external radio frequency field carrier signal, converting the radio frequency field carrier signal into an electrical signal, and sending the signal generated by the passive node tag chip; an analog front-end module for providing the signal required by a digital baseband module; the digital baseband module determines the working protocol unit according to an enable signal to obtain output data; a non-volatile memory for storing a LoRa activation password; an RFID reader for sending a command to read the non-volatile memory and read the LoRa activation password. The system realizes the integration of a passive Internet of Things node tag chip with low power consumption, low cost and long-distance communication.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a system based on a passive node tag chip compatible with long-distance communications. Background Art

[0002] Currently, the Passive Internet of Things (P-IoT) is limited by uplink communication distance, sensor node power consumption and cost, and infrastructure deployment and maintenance costs, resulting in limitations in the deployment of commercial P-IoT and further application upgrades.

[0003] The current dominant communication technology for passive IoT has a maximum communication range of just over ten meters, making it difficult to meet the requirements of building an IoT ecosystem with wide coverage and long communication distances. This also significantly limits the system's deployment density. The shorter the uplink communication distance, the more node devices are required to deploy the same range, further exacerbating system cost pressures. Low-power wide area network (LPWAN) communication technologies currently used in the IoT all possess long-range communication capabilities. LoRa technology, with a spreading factor of SF=12, boasts a communication range of up to three kilometers in urban areas. However, these technologies all suffer from the need for active battery power, high power consumption of terminal node tags, and the need for external integrated crystal oscillators, resulting in complex integration and high costs. These factors make them unable to address the practical needs of passive IoT.

[0004] The introduction of backscatter communication technology offers a new solution to these challenges. Backscatter technology utilizes external radio frequency signals as carriers, eliminating the need for terminal node wireless communication modules to generate local carrier signals. Therefore, wireless data transmission requires only simple circuitry, significantly reducing terminal node power consumption and costs. The most widely used traditional backscatter technology is passive RFID, which is widely used in various fields such as logistics, agriculture, transportation, finance, and smart homes. Its terminal tag nodes offer advantages such as ultra-low power consumption (microwatts), low costs, and a mature commercial system. However, as commercial deployments continue to expand and become more widespread, the cost and number of system access nodes, as well as uplink communication distance, have become bottlenecks restricting the technology's development.

[0005] Among current IoT wide-area network communication technologies, LoRa technology offers relatively lower power consumption and cost, as well as a longer communication range, leading to its rapid adoption within the IoT sector. The key to LoRa technology's long-range communication lies in its closed-source commercial physical layer encoding method and unique chirp frequency-shift modulation, which offers excellent noise immunity. Combining backscatter communication with LoRa technology, creating a multi-base communication system, can achieve passive long-range communication links. This addresses the IoT's challenges of low power consumption, low cost, and long-range communication.

[0006] In recent years, industry researchers have proposed several solutions combining backscatter communication technology with LoRa physical layer technology. Among them, CN109462419A, a LoRa backscatter communication system based on DDS direct digital frequency synthesis, uses DDS direct digital frequency synthesis technology for CSS linear frequency modulation to generate a chirp frequency-shifted square wave signal consistent with LoRa backscatter modulation. This square wave signal is then fed to a radio frequency switch to complete the LoRa backscatter modulation. However, this method requires active power, and the digital baseband processor requires a crystal oscillator to provide an operating clock, resulting in higher power consumption compared to passive tag nodes. Prior art proposes a solution that uses an energy harvesting unit in conjunction with an MCU to implement LoRa backscatter, rendering the node tag passive without requiring a battery. However, the tag consists of numerous discrete components, resulting in complex device connectivity and high costs. Furthermore, the digital square wave generation also requires a crystal oscillator on the MCU, making it difficult to widely adopt in passive IoT systems. Summary of the Invention

[0007] The present invention provides a system based on a passive node tag chip compatible with long-distance communication, thereby solving the problems in the prior art of complex device connections, high costs, and the fact that the generation of digital square waves also requires a crystal oscillator drive on the MCU, making it difficult to popularize on a large scale in the passive Internet of Things. The present invention realizes the integration of a passive Internet of Things node tag chip that is low in power consumption, low in cost, and capable of long-distance communication.

[0008] The present invention provides a system based on a passive node tag chip compatible with long-distance communication, the system comprising: a passive node tag chip and an RFID reader; wherein the passive node tag chip comprises: an antenna, an analog front-end module, a digital baseband module and a non-volatile memory module;

[0009] The antenna is used to obtain external radio frequency field carrier signals, convert the radio frequency field carrier signals into electrical signals, and send signals generated by the passive node tag chip;

[0010] The analog front-end module is used to provide the signals required by the digital baseband module; wherein, the signals include: power signal, enable signal, reset signal and clock signal; wherein, the clock signal is obtained by forming a clock-modulated carrier signal in the air through an external carrier auxiliary device and demodulating the clock-modulated carrier signal according to the demodulation circuit submodule;

[0011] The digital baseband module is used to determine whether the enable signal is at a high level. If not, the LoRa protocol unit in the digital baseband module enters a working state to obtain LoRa output data; if so, the RFID protocol unit in the digital baseband module enters a working state to obtain RFID output data and LoRa output data;

[0012] The RFID protocol unit in the digital baseband module enters a working state and obtains RFID output data and LoRa output data, including:

[0013] Obtaining a memory read command sent by the RFID reader, and reading the LoRa activation password in the first address in the LoRa configuration area in the non-volatile memory module according to the memory read command;

[0014] The RFID reader reads the protocol LoRa activation password in the RFID protocol unit, and determines whether the LoRa activation password and the protocol LoRa activation password are the same;

[0015] If they are the same, the passive node tag chip jumps to the LoRa protocol unit to work and obtains RFID output data and LoRa output data;

[0016] The non-volatile memory is used to store the LoRa activation password;

[0017] The RFID reader is used to send a command to read the non-volatile memory and read the LoRa activation password.

[0018] In one possible implementation, the analog front-end module includes: a demodulation circuit submodule, an RFID clock generation circuit submodule, a reset circuit submodule, an energy collection circuit submodule, a voltage stabilization circuit submodule, an energy detection circuit submodule, and a modulation circuit submodule;

[0019] The demodulation circuit submodule is used to convert the commands sent by the RFID reader and provide the main clock signal LoRa_CLK for the LoRa protocol unit;

[0020] The RFID clock generation circuit submodule is used to provide a clock signal CLK_RFID for the RFID protocol unit;

[0021] The reset circuit submodule is used to provide a reset signal RSTN for the digital baseband module;

[0022] The energy collection circuit submodule is used to convert the energy absorbed by the antenna into an electrical energy signal and store the converted energy in a capacitor;

[0023] The voltage stabilizing circuit submodule is used to provide the digital baseband module and the non-volatile memory module with a power supply signal VDD required for operation;

[0024] The energy detection circuit submodule is used to detect the electric energy generated by the energy collection circuit submodule, determine the difference between the electric energy and a preset value, and output the enable signal;

[0025] The modulation circuit submodule is used to perform uplink data transmission on the RFID output data and the LoRa output data, and send them through reflection from the antenna.

[0026] In one possible implementation, the RFID protocol unit is used to perform short-range communication with the RFID reader to obtain RFID output data;

[0027] The LoRa protocol unit is used to communicate with the LoRa device over a long distance to obtain LoRa output data.

[0028] In one possible implementation, the RFID protocol unit includes: a power-on initialization module, a downlink command decoding module, a downlink command parsing module, a random number module, a tag chip state jump module, an encoding output module, a memory interface timing control module, and a clock management module;

[0029] The power-on initialization module is used to obtain the status information of the passive node tag chip;

[0030] The downlink command decoding module is used to decode the downlink command RFID_DIN sent by the RFID reader to obtain decoded data; wherein the decoded data is 0, 1 binary bit stream data;

[0031] The downlink command parsing module is used to parse the decoded data to obtain the command type;

[0032] The random number module is used to generate random numbers; the random numbers are used to update labels;

[0033] The tag chip state jump module is used to jump the tag chip state according to the command type and determine the type of returned data;

[0034] The encoding output module is used to encode the RFID output data and the LoRa output data to obtain encoded data;

[0035] The memory interface timing control module is used to determine the read and write timing configuration of the encoded data;

[0036] The clock management module is used to turn on or off the clock of the RFID protocol unit.

[0037] In one possible implementation, the LoRa protocol unit includes: a process management module, a LoRa initialization module, a LoRa encoding module, a LoRa modulation module and a LoRa lookup table module;

[0038] The process management module is used to manage the clock of the LoRa protocol unit;

[0039] The LoRa initialization module is used to read the LoRa partition-related parameter configuration and LoRa valid data in the non-volatile memory module, and generate a memory interface timing signal to temporarily store the read data;

[0040] The LoRa encoding module is used to read data and encode the data to obtain LoRa encoded data;

[0041] The LoRa modulation module is used to process the LoRa coded data and generate a LoRa lookup table address cyclic shift method;

[0042] The LoRa lookup table module is used to generate a chirp square wave frequency shift signal according to the binary data corresponding to the LoRa lookup table address cyclic shift method.

[0043] In a possible implementation, the LoRa modulation module and the LoRa lookup table module operate synchronously.

[0044] In a possible implementation, the LoRa encoding module includes: a Hamming encoding unit, a whitening unit, an interleaving unit, and a Gray encoding unit connected in sequence.

[0045] In one possible implementation, the digital baseband module determines the working protocol unit according to the enable signal, and switches the protocol unit according to feedback information from the RFID reader to obtain RFID output data and LoRa output data, including:

[0046] Determine whether the enable signal is at a high level. If not, the LoRa protocol unit in the digital baseband module enters a working state to obtain LoRa output data.

[0047] If so, the RFID protocol unit in the digital baseband module enters a working state to obtain RFID output data and LoRa output data.

[0048] In one possible implementation, the RFID protocol unit in the digital baseband module enters a working state and obtains RFID output data and LoRa output data, including:

[0049] Obtain a memory read command sent by the RFID reader, and read the LoRa activation password in the first address in the LoRa configuration area in the non-volatile memory module according to the memory command;

[0050] The RFID reader reads the protocol LoRa activation password in the RFID protocol unit, and determines whether the LoRa activation password and the protocol LoRa activation password are the same;

[0051] If they are the same, the passive node tag chip jumps to the LoRa protocol unit to work and obtains RFID output data and LoRa output data.

[0052] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0053] (1) The present invention provides a system based on a passive node tag chip compatible with long-distance communication. The tag chip supports both RFID and LoRa communication protocol operating modes. By designing a top-level tag chip operating mode switching scheme, the RFID system achieves perfect on-chip compatibility with LoRa backscatter communication. In the RFID protocol operating mode, the system can communicate with commercial RFID readers at close range and modify LoRa partition-related parameters and LoRa valid data in the non-volatile memory. In the LoRa protocol operating mode, the tag chip achieves long-distance communication with ultra-low power consumption through the LoRa backscatter scheme.

[0054] (2) The present invention uses a pure digital circuit with a lookup table method to generate a chirp frequency-shifted square wave signal to implement the LoRa backscatter communication solution, which greatly reduces node power consumption compared to the traditional frequency synthesizer solution. The binary data of the up chirp signal with a complete LoRa symbol value of 0 is stored in ROM, and the initial address of the lookup table for each LoRa symbol is calculated. The LoRa lookup table address cyclic shift scheme is generated, and the binary data corresponding to the address is output according to the address cyclic shift scheme. The chirp square wave frequency-shift signal is generated and output to the RF switch of the analog front-end modulation module to realize LoRa backscatter modulation communication.

[0055] (3) In the LoRa protocol working mode, the passive node tag chip of the present invention transfers the working clock source required by the LoRa protocol unit in the digital baseband of the tag chip to the external carrier auxiliary equipment, and demodulates the external clock modulation carrier through the analog front-end module to obtain the working clock of the digital baseband LoRa protocol unit, and provides the power supply required for the operation of the LoRa physical layer protocol unit. The tag chip itself does not generate a clock and the chip does not need to integrate a crystal oscillator, which further effectively reduces the power consumption of the tag node and can realize true passive LoRa backscatter communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The overall structure of a passive node chip compatible with long-distance communication provided by an embodiment of the present invention;

[0057] Figure 2 A digital baseband architecture for a passive node chip compatible with long-distance communications provided in an embodiment of the present invention;

[0058] Figure 3 Schematic diagram of the chip implementing LoRa backscatter communication and the corresponding spectrum provided in an embodiment of the present invention;

[0059] Figure 4 The LoRa coding transmission system provided by the embodiment of the present invention;

[0060] Figure 5 A flowchart of the passive node chip compatible with long-distance communication provided by an embodiment of the present invention;

[0061] Figure 6 The invention provides a method for supplying energy and generating clocks in the LoRa protocol working mode of a passive node tag chip. DETAILED DESCRIPTION

[0062] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0063] The present invention provides a system based on a passive node tag chip compatible with long-distance communication, the system comprising: a passive node tag chip and an RFID reader; Figure 1 As shown, the chip includes: an antenna, an analog front-end module, a digital baseband module and a non-volatile memory module.

[0064] The antenna is used to acquire external RF carrier signals, convert them into electrical signals, and transmit the signals generated by the passive node tag chip. Specifically, the antenna acts as a "bridge" for communication between the tag chip and other external devices. It primarily performs two functions: first, converting external RF carrier signals into the electrical signals required by the chip; second, transmitting the uplink data signals generated by the chip through the antenna.

[0065] The analog front-end module is used to provide the signals required by the digital baseband module; the signals include: power signal, enable signal, reset signal and clock signal; the clock signal is generated for the RFID protocol unit in the digital baseband by the RFID clock generation circuit submodule.

[0066] Specifically, the analog front-end module includes: a demodulation circuit submodule, an RFID clock generation circuit submodule, a reset circuit submodule, an energy collection circuit submodule, a voltage stabilization circuit submodule, an energy detection circuit submodule, and a modulation circuit submodule.

[0067] The demodulation circuit submodule is used to convert the commands sent by the RFID reader and provide the main clock signal LoRa_CLK for the LoRa protocol unit.

[0068] The RFID clock generation circuit submodule is used to provide a clock signal CLK_RFID for the RFID protocol unit.

[0069] The reset circuit submodule is used to provide a reset signal RSTN for the digital baseband module.

[0070] The energy harvesting circuit submodule is used to convert the energy absorbed by the antenna into an electrical energy signal and store the converted energy in a capacitor.

[0071] The voltage stabilizing circuit submodule is used to provide the digital baseband module and the non-volatile memory module with the power supply signal VDD required for their operation.

[0072] The energy detection circuit submodule is used to detect the electric energy generated by the energy collection circuit submodule, determine the size of the electric energy and the preset value, and output an enable signal.

[0073] The modulation circuit submodule is used to transmit the RFID output data and the LoRa output data uplink and send them through reflection from the antenna.

[0074] Exemplarily, the analog front-end module first converts the energy absorbed by the antenna from the external environment into electrical energy that can be used by other circuits through the energy collection circuit sub-module, and stores the converted energy in the capacitor as the energy source for the entire tag chip; provides the power supply signal VDD required for the digital baseband and non-volatile memory through the voltage stabilization circuit sub-module; provides the reset signal RSTN for the digital baseband through the reset circuit sub-module; provides the clock signal CLK_RFID for the RFID protocol unit in the digital baseband through the RFID clock generation circuit sub-module; converts the command signal sent by the RFID reader into a square wave signal RFID_DIN that can be processed by the digital baseband through the demodulation circuit sub-module to realize the downlink communication of the RFID system, and is responsible for providing the main clock signal LoRa_CLK for the LoRa protocol unit in the digital baseband; completes the switching of the tag chip working mode through the enable signal ENERGY output by the energy detection circuit sub-module; transmits the data RFID_DOUT or LoRa_DOUT that needs to be returned after the digital baseband processing through the modulation circuit sub-module for uplink data transmission, and sends it to the air through antenna reflection.

[0075] The digital baseband module determines the working protocol unit according to the enable signal, and switches the protocol unit according to the feedback information of the RFID reader to obtain RFID output data and LoRa output data; the protocol unit includes: RFID protocol unit and LoRa protocol unit.

[0076] For the specific architecture of the digital baseband module, refer to Figure 2 The RFID protocol unit and the LoRa protocol unit are primarily comprised of a digital baseband module, which performs protocol control processing for passive nodes and memory timing configuration. The module details the digital baseband circuit architectures for both communication protocols. The RFID protocol unit is responsible for short-range communication between the tag chip and the RFID reader, while the LoRa protocol unit uses a purely digital solution to generate the frequency-shifted chirp square wave signal required for LoRa backscatter communication, responsible for long-range communication with commercial LoRa devices. The tag chip consumes less than 10 microwatts in LoRa protocol mode, making it suitable for successful commercial passive IoT applications.

[0077] Specifically, the RFID protocol unit includes a power-on initialization module (INIT), a downlink command decoding module (DECODER), a downlink command parsing module (CMD_PARSE), a random number module (RNG), a tag chip status jump module (SCU), an encoding output module (OCU), a memory interface timing control module (IE), and a clock management module (PMU). All modules operate under the CLK_RFID clock domain generated by the RFID clock generation circuit submodule.

[0078] The power-on initialization module (INIT) is used to obtain the status information of the passive node tag chip, such as the tag's EPC data, PC code, deactivation password, access password, and random number seed data.

[0079] The downlink command decoding module (DECODER) is used to decode the downlink command RFID_DIN sent by the RFID reader to obtain decoded data; the decoded data is 0, 1 binary bit stream data

[0080] The downlink command parsing module (CMD_PARSE) is used to parse the decoded data to obtain the command type. Specifically, the downlink command parsing module (CMD_PARSE) mainly parses the 0 and 1 binary bit stream data output by the decoding module (DECODER) to accurately identify the specific command type sent by the reader.

[0081] The random number module (RNG) is used to generate random numbers; random numbers are used to update tags. Specifically, the random number module (RNG) is mainly responsible for generating and updating the random numbers required when the tag communicates with the RFID reader.

[0082] The tag chip status jump module (SCU) is used to jump the tag chip status according to the command type and determine the type of returned data.

[0083] The coding output module (OCU) is used to encode the RFID output data and the LoRa output data to obtain coded data.

[0084] The memory interface timing control module (IE) is used to determine the read and write timing configuration of the encoded data. Specifically, the memory interface timing control module (IE) is responsible for the memory read and write timing configuration when reading and writing memory data.

[0085] The clock management module (PMU) is used to turn on or off the clock of the RFID protocol unit.

[0086] Specifically, the LoRa protocol unit includes: a process management module (CMU), a LoRa initialization module (LoRa_INIT), a LoRa encoding module (LoRa_ENCODE), a LoRa modulation module (LoRa_MOD), and a LoRa lookup table module (LoRa_ROM). All modules operate in the LoRa_CLK signal clock domain provided by the demodulation circuit submodule for the digital baseband.

[0087] The process management module is used to manage the clock of the LoRa protocol unit.

[0088] The LoRa initialization module is used to read the LoRa partition-related parameter configuration and LoRa valid data in the non-volatile memory module, and generate the memory interface timing signal to temporarily store the read data;

[0089] The LoRa encoding module is used to read data and encode the data to obtain LoRa encoded data. Specifically, Figure 4 As shown, the LoRa encoding module includes: Hamming encoding units connected in sequence (Hamming

[0090] encoding), whitening unit (Whitening), interleaving unit (Interleaving) and Gray coding unit (Gray

[0091] indexing).

[0092] The LoRa modulation module processes the LoRa encoded data and generates a cyclic shift scheme for the LoRa lookup table address. Here, the LoRa modulation module and the LoRa lookup table module operate synchronously. Specifically, the LoRa_MOD and LoRa_ROM modules operate synchronously and insert a preamble before the encoded LoRa symbol. They also calculate the initial address of the lookup table for each LoRa symbol and generate a cyclic shift scheme for the LoRa lookup table address.

[0093] The LoRa lookup table module is used to generate a square-wave frequency-shifted chirp signal based on the binary data corresponding to the LoRa lookup table address cyclic shift method. Specifically, the LoRa_ROM module stores the binary data of the up chirp signal with a complete LoRa symbol value of 0. It outputs the binary data corresponding to the address according to the address cyclic shift scheme to generate a square-wave frequency-shifted chirp signal. This signal is then output to the RF switch of the analog front-end modulation module to implement LoRa backscatter modulation.

[0094] Specifically, the RFID protocol unit is used to perform short-range communication with the RFID reader to obtain RFID output data;

[0095] The LoRa protocol unit is used to communicate with the LoRa device over long distances and obtain LoRa output data.

[0096] Specifically, in the digital baseband module, the digital baseband module determines the working protocol unit according to the enable signal, and switches the protocol unit according to the feedback information of the RFID reader to obtain RFID output data and LoRa output data, including the following steps:

[0097] (1) Determine whether the enable signal is high level. If not, the LoRa protocol unit in the digital baseband module enters the working state and obtains the LoRa output data;

[0098] (2) If yes, the RFID protocol unit in the digital baseband module enters the working state and obtains RFID output data and LoRa output data.

[0099] Specifically, the RFID protocol unit in the digital baseband module enters the working state and obtains RFID output data and LoRa output data, including:

[0100] (2.1) Obtain the memory read command sent by the RFID reader, and read the LoRa activation password in the first address of the LoRa configuration area in the non-volatile memory module according to the memory command.

[0101] (2.2) The RFID reader reads the protocol LoRa activation password in the RFID protocol unit and determines whether the LoRa activation password and the protocol LoRa activation password are the same.

[0102] (2.3) If they are the same, the passive node tag chip jumps to the LoRa protocol unit to work and obtains RFID output data and LoRa output data.

[0103] In a specific embodiment provided by the present invention, the basic mechanism for implementing LoRa backscatter modulation is the backscatter frequency shifting principle. When the RF switch controls the reflection coefficient to perform periodic and uniform switching, the intermediate frequency signal carrying data information generated inside the tag can be shifted to another fixed frequency. At this time, the backscatter offset frequency is also a fixed frequency. If the backscatter offset frequency is a constantly changing frequency, for example, in LoRa modulation, the signal is a linear frequency modulation signal that increases or decreases linearly over time. At this time, if the switching speed of the RF switch is also controlled to increase or decrease linearly, the square wave frequency represented by the backscatter coefficient will also increase or decrease linearly. This square wave waveform is a uniformly narrowed or uniformly widened shape, causing the backscatter offset frequency to also increase or decrease linearly. By controlling the switching speed of the RF switch, linearly increasing or decreasing at the chip transmission rate of the LoRa symbol, and sweeping the entire signal bandwidth within the air transmission time of a LoRa physical layer symbol, a backscatter LoRa modulated signal can be generated.

[0104] Assume that the LoRa modulation signal bandwidth is , the spreading factor is SF, and the starting frequency of the intermediate frequency square wave signal inside the tag is , the external carrier frequency is , then the sweep range of the intermediate frequency square wave signal is [ , ], the actual frequency sweep range of the backscattered signal is [ , ]and[ , ]. One LoRa symbol duration , the rate at which the LoRa modulation signal increases linearly is It uses backscattering to implement LoRa modulation and the corresponding spectrum diagram is as follows Figure 3 shown.

[0105] The working status diagram of the passive node tag chip, refer to Figure 5 .

[0106] When the tag chip is in an RF energy field, it powers up and enters initialization mode. After initialization is complete, if the RF energy field is weak, the energy detection circuit submodule's output enable signal (ENERGY) goes low, and the tag chip enters LoRa protocol mode. When the RF energy field is strong, the voltage doubler rectifier circuit outputs a high voltage, and the energy detection circuit submodule's output enable signal (ENERGY) goes high, causing the tag chip to enter RFID protocol mode. In RFID protocol mode, a read memory command can be sent through the RFID reader to read the address data in the LoRa configuration area. If the address data matches the LoRa activation password, the tag chip will also switch to LoRa protocol mode.

[0107] The tag chip power supply and clock generation scheme in the LoRa protocol working mode is as follows: Figure 6 . The clock source required for the operation of the digital baseband LoRa protocol unit of the tag chip is transferred to the external carrier auxiliary device. When the external carrier auxiliary device transmits the radio frequency carrier, the desired clock signal is modulated onto this carrier to form a clock modulated carrier signal in the air. The tag chip uses the energy acquisition circuit submodule to power the tag chip, and uses the demodulation circuit submodule to demodulate the clock modulated carrier signal. The demodulated clock signal provides a working clock signal for the LoRa protocol unit. Since the clock signal modulated by the clock modulated carrier signal is provided by an external signal source or a crystal oscillator, its demodulated clock accuracy is relatively high and can meet the working requirements of LoRa backscatter communication. This solution of the present invention combines the chip radio frequency carrier energy source and the clock source, which can simultaneously solve the problems of the passivity of the tag node of LoRa backscatter communication and the generation of the precise clock required for LoRa backscatter communication.

[0108] The non-volatile memory is used to save the LoRa activation password.

[0109] The RFID reader is used to send commands to read the non-volatile memory and read the LoRa activation password.

[0110] This invention provides an integrated passive node tag chip architecture compatible with both RFID and LoRa backscatter communication protocols. Compared to commercially available active LoRa chips, the proposed passive node tag chip can achieve power consumption as low as 10 microwatts or less in LoRa backscatter mode, enabling successful application in commercial passive IoT systems. Compared to traditional ultra-high frequency RFID tag chips, the proposed architecture significantly extends the uplink communication range of LoRa backscatter communication, significantly reducing the cost of passive IoT systems, expanding system deployment, and further promoting the application and upgrading of commercial passive IoT systems.

[0111] The LoRa protocol unit in the digital baseband of the passive node tag chip of the present invention adopts a pure digital circuit with a lookup table method to generate the chirp frequency-shifted square wave signal required for LoRa backscatter communication. Compared with the traditional frequency synthesizer solution, it removes the complex calculation and processing process of the traditional frequency synthesizer, successfully reduces the power consumption of the LoRa backscatter node circuit to the microwatt level, and can be effectively applied in the passive Internet of Things in the commercial sector.

[0112] In operating mode, the passive node tag chip of this invention uses an external carrier source to modulate the clock to generate a clock-modulated carrier. This not only powers the tag chip but also provides an operating clock for the LoRa protocol unit in the digital baseband. This also takes into account clock accuracy requirements, eliminating the need for integrated crystal oscillators and batteries. This significantly improves chip integration and reduces system layout costs while reducing the power consumption of the passive node tag. It also provides a feasible direction for the subsequent passiveization of LoRa backscatter tags.

[0113] The various embodiments in this specification are described in a progressive manner. References to the same or similar parts between the various embodiments are sufficient. Each embodiment focuses on the differences from other embodiments. All or part of the present invention can be used in a variety of general or specialized computer system environments or configurations. For example, personal computers, server computers, handheld or portable devices, tablet devices, mobile communication terminals, multiprocessor systems, microprocessor-based systems, programmable electronic devices, network PCs, minicomputers, mainframe computers, and distributed computing environments that include any of the above systems or devices.

[0114] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the present invention.

Claims

1. A system based on a passive node tag chip compatible with long-distance communication, characterized in that: include: Passive node tag chip and RFID reader; wherein the passive node tag chip includes: an antenna, an analog front-end module, a digital baseband module and a non-volatile memory module; The antenna is used to obtain external radio frequency field carrier signals, convert the radio frequency field carrier signals into electrical signals, and send signals generated by the passive node tag chip; The analog front-end module is used to provide the signals required by the digital baseband module, including: power signal, enable signal, reset signal and clock signal; wherein, the clock signal is formed by forming a clock-modulated carrier signal in the air through an external carrier auxiliary device, and the analog front-end module demodulates the clock-modulated carrier signal according to the demodulation circuit submodule to obtain the signal; The digital baseband module is used to determine whether the enable signal is at a high level. If not, the LoRa protocol unit in the digital baseband module enters a working state to obtain LoRa output data; if so, the RFID protocol unit in the digital baseband module enters a working state to obtain RFID output data and LoRa output data; The RFID protocol unit in the digital baseband module enters a working state and obtains RFID output data and LoRa output data, including: Obtaining a memory read command sent by the RFID reader, and reading the LoRa activation password in the first address in the LoRa configuration area in the non-volatile memory module according to the memory read command; The RFID reader reads the protocol LoRa activation password in the RFID protocol unit, and determines whether the LoRa activation password and the protocol LoRa activation password are the same; If they are the same, the passive node tag chip jumps to the LoRa protocol unit to work and obtains RFID output data and LoRa output data; The non-volatile memory is used to store the LoRa activation password; The RFID reader is used to send a command to read the non-volatile memory and read the LoRa activation password.

2. The system based on a passive node tag chip compatible with long-distance communication according to claim 1, characterized in that: The analog front-end module includes: a demodulation circuit submodule, an RFID clock generation circuit submodule, a reset circuit submodule, an energy collection circuit submodule, a voltage stabilization circuit submodule, an energy detection circuit submodule, and a modulation circuit submodule; The demodulation circuit submodule is used to convert the commands sent by the RFID reader and provide the main clock signal LoRa_CLK for the LoRa protocol unit; The RFID clock generation circuit submodule is used to provide a clock signal CLK_RFID for the RFID protocol unit; The reset circuit submodule is used to provide a reset signal RSTN for the digital baseband module; The energy collection circuit submodule is used to convert the energy absorbed by the antenna into an electrical energy signal and store the converted energy in a capacitor; The voltage stabilizing circuit submodule is used to provide the digital baseband module and the non-volatile memory module with a power supply signal VDD required for operation; The energy detection circuit submodule is used to detect the electric energy generated by the energy collection circuit submodule, determine the difference between the electric energy and a preset value, and output the enable signal; The modulation circuit submodule is used to perform uplink data transmission on the RFID output data and the LoRa output data, and send them through reflection from the antenna.

3. The system based on a passive node tag chip compatible with long-distance communication according to claim 1, characterized in that: The RFID protocol unit is used to perform short-range communication with the RFID reader to obtain RFID output data; The LoRa protocol unit is used to communicate with the LoRa device over a long distance to obtain LoRa output data.

4. The system based on a passive node tag chip compatible with long-distance communication according to claim 1, characterized in that: The RFID protocol unit includes: a power-on initialization module, a downlink command decoding module, a downlink command parsing module, a random number module, a tag chip state jump module, a coding output module, a memory interface timing control module and a clock management module; The power-on initialization module is used to obtain the status information of the passive node tag chip; The downlink command decoding module is used to decode the downlink command RFID_DIN sent by the RFID reader to obtain decoded data; wherein the decoded data is 0, 1 binary bit stream data; The downlink command parsing module is used to parse the decoded data to obtain the command type; The random number module is used to generate random numbers; the random numbers are used to update labels; The tag chip state jump module is used to jump the tag chip state according to the command type and determine the type of returned data; The encoding output module is used to encode the RFID output data and the LoRa output data to obtain encoded data; The memory interface timing control module is used to determine the read and write timing configuration of the encoded data; The clock management module is used to turn on or off the clock of the RFID protocol unit.

5. The system based on a passive node tag chip compatible with long-distance communication according to claim 1, characterized in that: The LoRa protocol unit includes: a process management module, a LoRa initialization module, a LoRa encoding module, a LoRa modulation module and a LoRa lookup table module; The process management module is used to manage the clock of the LoRa protocol unit; The LoRa initialization module is used to read the LoRa partition-related parameter configuration and LoRa valid data in the non-volatile memory module, and generate a memory interface timing signal to temporarily store the read data; The LoRa encoding module is used to read data and encode the data to obtain LoRa encoded data; The LoRa modulation module is used to process the LoRa coded data and generate a LoRa lookup table address cyclic shift method; The LoRa lookup table module is used to generate a chirp square wave frequency shift signal according to the binary data corresponding to the LoRa lookup table address cyclic shift method.

6. The system based on a passive node tag chip compatible with long-distance communication according to claim 5, characterized in that: The LoRa modulation module and the LoRa lookup table module work synchronously.

7. The system based on a passive node tag chip compatible with long-distance communication according to claim 5, characterized in that: The LoRa encoding module includes a Hamming encoding unit, a whitening unit, an interleaving unit and a Gray encoding unit connected in sequence.

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