A passive tag communication system based on distributed energization

Abstract

A passive tag communication system based on distributed energization includes a reader gateway, a passive tag and one or more distributed excitation sources; the distributed excitation sources supply energy for the passive tag within the energization signal coverage range thereof. The interaction process of each device in the system is as follows: before starting communication with the passive tag, the reader gateway sends an energization start instruction to the distributed excitation source; the excitation source starts energization after receiving the energization instruction, and returns an end signal to the reader gateway after the energization is completed; the reader gateway starts the inventory of the passive tag after receiving the end signal; and the tag information is transmitted to the cloud or the application end after the inventory of the passive tag is completed. The application improves the downlink communication distance of the reader gateway to the passive tag, improves the receiving sensitivity of the reader, and improves the uplink communication distance of the passive tag to the reader.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Internet of Things, and particularly relates to a passive tag communication system based on distributed energy supply. BACKGROUND

[0002] The progress of RFID (Radio Frequency IDentification) technology greatly promotes the development of Internet of Things industry. RFID tags are divided into active tags and passive tags. Active tags are equipped with batteries or need external power supply, and the service life depends on the battery life. The external power supply charging mode also causes the tag to work unstably, and greatly increases the cost of the tag. Therefore, passive tags have attracted widespread attention.

[0003] The current passive RFID tag communicates with an RFID reader. The RFID reader first transmits a PIE coded radio frequency signal to the tag, which simultaneously serves as real-time energy supply to the tag and issues instructions. After the RFID reader sends the coded radio frequency signal, it continues to transmit a single-tone carrier signal, which charges the tag and allows the tag to return information to the RFID reader through backscatter. The RFID reader demodulates the information returned by the tag while continuously transmitting the single-tone carrier signal.

[0004] The current passive RFID tag communication scheme has the following problems:

[0005] 1. The communication distance between the RFID reader and the tag is limited by the reading sensitivity of the tag. When the radio frequency signal sent by the RFID reader reaches the tag, the energy attenuation is too much to wake up the tag. The limit of this communication distance is usually 15 m.

[0006] 2. Low receiving sensitivity of the RFID reader due to carrier interference. Since the RFID reader emits a high-power carrier signal while demodulating the signal returned by the tag, it causes blocking interference to the demodulation of the RFID reader, reducing the receiving sensitivity of the RFID reader. SUMMARY

[0007] In order to solve the above problems, improve the communication distance between the passive tag and the RFID reader gateway, and reduce the application cost of the passive tag, the present application proposes a passive tag communication system based on distributed energy supply.

[0008] The core of the present application is to split the functions of energy supply and communication of the traditional RFID reader gateway to the tag, reduce the blocking interference received by the RFID reader gateway by reducing the power of the carrier signal emitted by the RFID reader gateway. At the same time, the passive tag in the present technical solution has a certain endurance compared with the traditional RFID tag, and adopts an active backscatter modulation mode, which improves the signal power returned to the RFID reader.

[0009] In the present application, the passive tag refers to a passive RFID tag, and the reader gateway refers to an RFID reader gateway.

[0010] The specific technical solutions are as follows:

[0011] A passive tag communication system based on distributed energizing includes a reader gateway and a passive tag in communication with each other. It also includes one or more distributed energizing sources; the distributed energizing sources provide energy for the passive tags within their energizing signal coverage range;

[0012] The reader gateway only communicates with the passive tags within its communication signal coverage range;

[0013] The reader gateway only interacts with the distributed energizing sources within its communication signal coverage range;

[0014] The communication and energizing methods between each device in the passive tag communication system within the corresponding communication signal coverage range or energizing signal coverage range are as follows:

[0015] S1, the distributed energizing source interacts with the reader gateway:

[0016] When the distributed energizing source receives the energizing-on instruction from the reader gateway for the corresponding passive tag, it starts to emit radio frequency energy externally to energize the passive tag; after energizing is completed, the energizing source returns a ready instruction to the reader gateway, indicating that the corresponding passive tag is ready and can communicate with the reader gateway;

[0017] S2, the reader gateway communicates with the passive tag:

[0018] Before communication starts, the reader gateway sends an energizing instruction to the distributed energizing source; after the energizing source completes energizing the corresponding passive tag, it transmits an energizing completion signal back to the reader gateway; after the reader gateway receives the energizing completion signal, it starts to inventory the passive tag; after inventorying is completed, it transmits the passive tag information to the cloud or application end;

[0019] During the communication process, the reader gateway only provides a reflectable carrier signal for the passive tag;

[0020] S3, energizing between the passive tag and the distributed energizing source, and transmitting data to the reader gateway;

[0021] The energy storage unit of the passive tag receives the radio frequency signal emitted by the energizing source through the antenna and stores sufficient energy;

[0022] When the passive tag receives the signaling sent by the reader gateway, it analyzes and processes the signaling to generate a corresponding data frame; then it feeds back the data frame information to the reader gateway.

[0023] Further, in step S1, the distributed excitation source determines the shortest energizing time according to the energizing signal power intensity, the energizing signal coverage range, and the polling communication time of the reader gateway and the corresponding passive tag, to ensure that the passive tag can perform one complete signaling interaction with the reader gateway after energizing.

[0024] The shortest energizing time indicates that the distributed excitation source has a shortest energizing time to ensure that the passive tag can perform one complete signaling interaction with the reader gateway after energizing. The shortest energizing time is equal to the energy (work) required for the energized passive tag to communicate and interact with the reader gateway once, divided by the lowest energizing power actually achieved by the distributed excitation source to the passive tag end (for example, in an ideal state, the energizing power at the edge of the energizing signal coverage range, and under the influence of other factors, the energizing power at non-edge positions may also be the lowest power).

[0025] Further, the distributed excitation source includes a communication module, a signal transmitting source, and a microprocessor.

[0026] The number of distributed excitation sources is related to their energizing signal power and energizing signal coverage range.

[0027] The communication module of the distributed excitation source is used to interact with the reader gateway for instructions: when the communication module receives the energizing instruction started by the reader gateway, the signal transmitting source starts to emit radio frequency energy, and the distributed excitation source starts to energize the passive tag.

[0028] The microprocessor of the distributed excitation source determines the shortest energizing time.

[0029] After the distributed excitation source completes energizing, the microprocessor controls the communication module to return a ready instruction to the reader gateway, indicating the end of energizing.

[0030] Specifically, in the distributed excitation source, the microprocessor controls the signal transmitting source to emit energizing electromagnetic waves and starts counting. When the preset shortest energizing time is reached, the signal transmitting source interrupts the emission and returns a ready instruction to the reader gateway.

[0031] Further, the passive tag includes an energy storage unit, an active backscatter modulation module, an antenna, and a digital baseband.

[0032] The energy storage unit receives the radio frequency signal emitted by the excitation source through the antenna, stores sufficient energy, and supplies power to the active backscatter modulation module and the digital baseband for subsequent communication;

[0033] When the passive tag receives the signaling sent by the reader gateway, the digital baseband analyzes and processes the signaling according to the communication protocol, generates a corresponding data frame, and feeds back the data frame information to the reader gateway through the active backscatter modulation module.

[0034] Specifically, the passive tag, the energy storage capacity of the energy storage unit is sufficient to support the passive tag to work once a complete tag disk storage period;

[0035] The active backscatter module controls the antenna port reflection coefficient through a switching device, realizes the modulation of information and the gain of backscatter signal;

[0036] The digital baseband analyzes the signaling received when communicating with the reader gateway, generates corresponding reply data frames according to the communication protocol, and modulates the data frame information through the active backscatter modulation module and feeds back to the reader gateway.

[0037] The present application has the following beneficial effects:

[0038] 1. The downlink communication distance of the reader gateway to the tag is improved. The energy source of the passive tag is converted from the radio frequency signal emitted by the reader to a distributed excitation source, so that the tag reading sensitivity is improved, and the downlink communication distance of the reader gateway to the tag is increased.

[0039] 2. The receiving sensitivity of the reader is improved. The carrier signal emitted by the reader does not need to provide energy for the tag, but only needs to be used as a carrier for information transmission, so the transmission power can be greatly reduced, and the carrier blocking interference caused by the demodulation of the reader is also reduced, thereby improving the receiving sensitivity of the reader.

[0040] 3. The uplink communication distance of the passive tag to the reader is improved. The passive tag uses an active backscatter mode, and compared with the passive backscatter mode, the return signal power is increased by 5-10dB, thereby increasing the uplink communication distance of the passive tag. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 It is a whole schematic diagram of the distributed energy supply passive tag communication system.

[0042] Figure 2 It is a schematic diagram of the distributed excitation source structure.

[0043] Figure 3 It is a schematic diagram of the passive tag structure.

[0044] Figure 4 It is a layout schematic diagram of the distributed energy supply passive tag communication system. DETAILED DESCRIPTION

[0045] To solve the communication range problem of the reader and the passive tag in the prior art, the present application proposes a passive tag communication system based on distributed energy supply. The principle of the present application is described as follows:

[0046] The passive tag communication system based on distributed energizing source comprises a distributed energizing source, a reader gateway and a passive tag.

[0047] The distributed energizing source comprises a communication module, a signal transmitting source and a microprocessor. The communication module of the distributed energizing source is responsible for interaction with the reader gateway. When the communication module receives an energizing instruction from the reader gateway, the signal transmitting source starts to transmit radio frequency energy, and the distributed energizing source starts to energize the passive tag. The microprocessor of the distributed energizing source determines a shortest energizing time according to the energizing signal power intensity, the coverage range of the distributed energizing source and the polling communication time of the reader gateway and the tag, so as to ensure that the passive tag can perform a complete signaling interaction with the reader gateway after energizing. After the energizing is completed, the microprocessor controls the communication module to return a ready instruction to the reader gateway, indicating that the passive tag is ready for communication with the reader gateway.

[0048] The reader gateway is the core of the communication system. Before communication with the passive tag, the reader gateway sends an energizing instruction to the distributed energizing source. After the energizing is completed, the reader gateway receives an energizing end signal from the distributed energizing source. The reader gateway only needs to provide a reflective carrier signal for the tag, which can reduce the transmitted carrier signal power and reduce the influence of carrier interference on demodulation sensitivity.

[0049] The passive tag has a large-capacity energy storage unit, an active backscatter modulation module, an antenna and a digital baseband. The energy storage unit of the passive tag receives the radio frequency signal transmitted by the energizing source through the antenna, stores sufficient energy, and supplies energy to the active backscatter modulation module and the digital baseband in subsequent communication. When the passive tag receives the signaling sent by the reader gateway, the digital baseband analyzes and processes the signaling according to the communication protocol, generates a corresponding data frame, and feeds back the data frame information to the reader gateway through the active backscatter modulation module.

[0050] The key of the present application is to change the energy acquisition mode of the passive tag from the traditional real-time supply of the reader carrier to the supply of the distributed energizing source. In addition, the distributed energizing source can energize the capacitor in the tag for a long time, and the coverage range of the energizing source depends on the rectification sensitivity of the tag.

[0051] The present application will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0052] The specific embodiment of the present application is shown in the whole system block diagram as Figure 1 The passive tag communication system comprises a reader gateway, a distributed energizing source and a passive tag, wherein:

[0053] The reader gateway controls the communication interaction process of the whole system and communicates with the passive tag to obtain corresponding information. When the reader gateway communicates with the passive tag, only a low-power carrier signal needs to be provided for the corresponding passive tag, thereby reducing the influence of carrier interference on demodulation sensitivity.

[0054] The interaction process of the distributed energy-supplied passive tag communication system is as follows:

[0055] 1. Before starting communication with the passive tag, the reader gateway sends an energizing instruction to the distributed excitation source.

[0056] 2. After receiving the energizing instruction, the excitation source starts energizing and returns an end signal to the reader gateway after energizing is completed.

[0057] 3. After receiving the end signal, the reader gateway starts checking the passive tag.

[0058] 4. After checking the passive tag, the tag information is transmitted to the cloud or the application end.

[0059] The distributed excitation source has a structure diagram as shown in Figure 2 After the communication module of the distributed excitation source receives the energizing instruction transmitted by the reader gateway, the microprocessor determines the energizing time according to the energizing signal power intensity, the energizing signal coverage range of the distributed excitation source, and the polling communication time of the reader gateway and the tag. The microprocessor controls the signal transmitting source to transmit the energizing electromagnetic wave and starts counting. When the specified minimum energizing time is reached, the signal transmitting source is interrupted from transmitting, and a ready instruction is returned to the reader gateway.

[0060] The passive tag has a structure diagram as shown in Figure 3 The functional modules of the passive tag include an energy storage unit, an active backscatter module, and a digital baseband part. The energy storage unit is used to collect and store the energizing electromagnetic wave transmitted by the distributed excitation source, and its storage capacity needs to be sufficient to support the tag to work once for a complete tag inventory cycle. The active backscatter module can control the antenna port reflection coefficient by turning on or off the MOSFET or PIN diode to realize the modulation of information and the gain of the backscatter signal. The digital baseband analyzes the signaling received when communicating with the reader gateway, generates corresponding reply data frames according to the ISO 18000 6C protocol, and modulates and amplifies the data frame information through the active backscatter modulation module to feed back to the reader gateway.

[0061] The distribution diagram of the system in this example is as shown in Figure 4As shown in the figure, 1 represents the reader gateway, 2-5 represent four distributed excitation sources respectively, the shaded part in the figure represents the range of passive tags that can be activated by the distributed excitation source, the dotted circle represents the range that the reader gateway can communicate with the activated passive tags, and the overlapping area of the dotted circle and the shaded part is the effective communication range of the reader gateway and the passive tags. The active backscatter module of the passive tag can improve the backscatter of the traditional RFID tag by 6-12 dB, which corresponds to an increase of 1 to 2 times in the communication coverage radius of the traditional RFID reader and the tag.

Claims

1. A passive tag communication system based on distributed power supply, comprising a reader gateway and passive tags that communicate with each other, wherein the passive tag refers to a passive RFID tag, and the reader gateway refers to an RFID reader gateway, characterized in that: It also includes one or more distributed excitation sources; the distributed excitation sources power the passive tags within the coverage area of ​​their charging signals; The reader gateway only communicates with passive tags within its communication signal coverage area; The reader gateway only interacts with distributed excitation sources within its communication signal coverage area; The communication and charging methods between devices in the passive tag communication system within the corresponding communication signal coverage area or charging signal coverage area are as follows: S1. The distributed stimulus source interacts with the reader / writer gateway to exchange commands: When the distributed excitation source receives the charging instruction from the reader gateway for the corresponding passive tag, it starts to transmit radio frequency energy to charge the passive tag. After charging is completed, the excitation source returns a ready instruction to the reader gateway, indicating that the corresponding passive tag is ready and can communicate with the reader gateway. S2. The reader / writer gateway communicates with the passive tag: Before communication begins, the reader gateway sends a charging command to the distributed excitation source; after the excitation source has finished charging the corresponding passive tag, it sends a charging end signal back to the reader gateway; after receiving the charging end signal, the reader gateway begins to inventory the passive tags; after the inventory is completed, the passive tag information is transmitted to the cloud or application. During communication, the reader gateway only provides reflective carrier signals to passive tags; S3, power supply between passive tags and distributed excitation sources, and data transmission to the reader gateway; The energy storage unit of the passive tag receives the radio frequency signal emitted by the excitation source through an antenna and stores energy; When a passive tag receives a signaling message from a reader gateway, it parses and processes the signaling message to generate a corresponding data frame. The data frame information is then fed back to the reader gateway.

2. The passive tag communication system based on distributed power supply according to claim 1, characterized in that in step S1, the distributed excitation source determines the shortest charging time based on the power intensity of the charging signal, the coverage range of the charging signal, and the polling communication time between the reader gateway and the corresponding passive tag, so as to ensure that the passive tag can perform a complete signaling interaction with the reader gateway after charging. The shortest charging time is: the energy required for a charged passive tag to communicate and interact with the reader gateway once, divided by the minimum charging power actually achieved by the corresponding distributed excitation source to the passive tag.

3. The passive tag communication system based on distributed power supply according to claim 1, characterized in that: The distributed excitation source includes a communication module, a signal transmitter, and a microprocessor; The number of distributed excitation sources is related to their charging signal power and charging signal coverage. The communication module of the distributed excitation source is used to interact with the reader gateway: when the communication module receives the reader gateway to start charging, the signal transmitter starts to emit radio frequency energy, and the distributed excitation source starts to charge the passive tag. The microprocessor of the distributed excitation source determines the shortest charging time; After the distributed excitation source completes charging, the microcontroller controls the communication module to return a ready instruction to the reader gateway, indicating that charging has ended.

4. The passive tag communication system based on distributed power supply according to claim 3, characterized in that: In the distributed excitation source, the microprocessor controls the signal transmitter to emit charging electromagnetic waves and starts counting. When the preset minimum charging time is reached, the signal transmitter stops transmitting and returns a ready command to the reader gateway.

5. The passive tag communication system based on distributed power supply according to claim 1, characterized in that: The passive tag includes an energy storage unit, an active backscatter modulation module, an antenna, and a digital baseband; The energy storage unit receives the radio frequency signal emitted by the excitation source through the antenna and stores enough energy to power the active inverse modulation module and digital baseband during subsequent communication. When a passive tag receives a signaling message from the reader gateway, the digital baseband analyzes and processes the signaling message according to the communication protocol, generates a corresponding data frame, and feeds the data frame information back to the reader gateway through the active backscatter modulation module.

6. The passive tag communication system based on distributed power supply according to claim 5, characterized in that: In the passive tag, the energy storage capacity of the energy storage unit is sufficient to support the passive tag to operate under power for one complete tag inventory cycle; The active backscatter module controls the reflection coefficient of the antenna port through switching devices to achieve information modulation and backscatter signal gain; When the digital baseband analyzer communicates with the reader gateway, it receives signaling and generates corresponding response data frames according to the communication protocol. The data frame information is then modulated and amplified by the active backscatter modulation module and fed back to the reader gateway.

Images