Passive communication method, passive tag, and related apparatus

Abstract

A passive communication method, which is used to increase passive tag sensing distance. In the passive communication method, an excitation signal is first sent to a passive tag to energize the passive tag, and a single-tone carrier signal is then sent to the passive tag once energizing of the passive tag is completed, so that the passive tag can reflect the single-tone carrier signal, and thereby send a reflected signal carrying identification information. Energizing a passive tag on the basis of an excitation signal before the passive tag sends a reflected signal by reflecting a single-tone carrier signal, allows the passive tag to have sufficient energy to send the reflected signal, thereby ensuring long-distance transmission of reflected signals sent by passive tags, and effectively increasing passive tag sensing distance.

Description

A passive communication method, a passive tag, and related devices

[0001] This application claims priority to Chinese Patent Application No. 202411540172.8, filed with the State Intellectual Property Office of China on October 30, 2024, entitled “A Passive Communication Method, Passive Tag and Related Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, and in particular to a passive communication method, a passive tag, and related devices. Background Technology

[0003] With the continuous development of communication technology, the application of Internet of Things (IoT) technology is becoming increasingly widespread. The characteristic of IoT is that it uses various wired or wireless communication technologies to connect IoT terminal nodes to achieve large-scale information collection and transmission, thereby enabling real-time perception and detection of the status of IoT objects.

[0004] In traditional wireless IoT technologies, most IoT terminals are battery-powered. Compared to fixed power sources, battery power increases the portability, mobility, and application range of IoT terminals, and alleviates the stringent power consumption requirements of IoT terminals to some extent. However, issues such as size, cost, and the inconvenience of battery replacement still exist.

[0005] With the development of green energy technologies, using wireless power to drive IoT terminals has become a hot topic in development and application. For example, taking Radio Frequency Identification (RFID) technology as an example, RFID tags with a passive design do not require battery power. Instead, they use radio frequency antennas and rectifier circuits to collect the radio electromagnetic wave energy emitted by the RFID reader, thereby driving the passive tag to work and realizing the passive nature of RFID tags.

[0006] However, the current passive RFID tags have a short sensing distance. RFID readers can only sense passive RFID tags when they are very close to them, which greatly affects the application of passive RFID tags. Summary of the Invention

[0007] This application provides a passive communication method that can improve the sensing distance of passive tags.

[0008] Firstly, a passive communication method is provided, applied to passive tags. This passive communication method includes: the passive tag receiving an excitation signal and charging itself based on the received excitation signal. After the passive tag is fully charged, it then receives a single-tone carrier signal. That is, the passive tag will not enter the working state of receiving single-tone carrier signals if it is not fully charged. Then, the passive tag reflects the single-tone carrier signal to send a reflected signal, which is used to indicate information about the passive tag.

[0009] In this scheme, an excitation signal is first sent to the passive tag to charge it. After the passive tag is fully charged, a single-tone carrier signal is sent to it, enabling the passive tag to reflect the single-tone carrier signal and transmit a reflected signal carrying identification information. Because the passive tag is first charged by the excitation signal and then reflects the single-tone carrier signal to transmit the reflected signal, it has sufficient energy to transmit the reflected signal, ensuring that the reflected signal can be transmitted over a longer distance, effectively improving the sensing range of the passive tag.

[0010] In one possible implementation, the passive tag begins receiving a single-tone carrier signal after it has been fully charged and an interruption of the excitation signal is detected. That is, the passive tag requires two conditions to begin operating: one is that it has been fully charged, and the other is that an interruption of the excitation signal has been detected.

[0011] In this scheme, by configuring the passive tag to only start receiving single-tone carrier signals after detecting an interruption in the excitation signal, it is possible to facilitate the synchronous operation between multiple communication devices and the passive tag, ensuring that communication devices that need to send excitation signals and receive reflected signals will not miss receiving reflected signals.

[0012] Furthermore, by configuring the passive tag's operating mode, this solution can employ multiple communication devices to separately transmit single-tone carrier signals and receive reflected signals transmitted by the passive tag. This separates the transmission of single-tone carrier signals and the reception of reflected signals into two independent communication devices, ensuring synchronous operation between the two independent communication devices. This solves the problem of high device costs caused by entrusting both signal transmission and reception to the same device (such as an RFID reader / writer). It ensures that this solution can be completed using two simple communication devices, effectively expanding the application scenarios of the solution.

[0013] In one possible implementation, after the passive tag is fully charged, it parses the excitation signal to obtain the first information indicated in the excitation signal. If the first information matches the information in the passive tag, the passive tag triggers the reception of a single-tone carrier signal.

[0014] In other words, if the first information in the excitation signal is different from the information of the passive tag, the passive tag will not trigger the reception of the single-tone carrier signal, and thus will not reflect the signal, so as to ensure that the first communication device or the second communication device can find the specific passive tag.

[0015] In one possible implementation, after the passive tag begins receiving the single-tone carrier signal, the passive tag delays the target duration before reflecting the single-tone carrier signal.

[0016] In this scheme, by setting the passive tag to reflect the single-tone carrier signal after a certain delay to obtain the reflected signal, the timing of the reflected signals sent by different passive tags can be staggered, avoiding mutual interference between the reflected signals.

[0017] In one possible implementation, the target duration is n times the preset duration, where n is an integer selected from a preset integer range for the passive tag, and the preset integer range includes multiple different integers.

[0018] In this scheme, by setting the target duration of the passive tag's delayed reflection of the single-tone carrier signal to n times the preset duration, the passive tag can randomly select the duration of the delayed reflection of the single-tone carrier signal within a certain range. This allows most passive tags to send reflected signals at different times, ensuring that the reflected signals sent by each passive tag can be received normally.

[0019] In one possible implementation, the single-tone carrier signal and the reflected signal reside on different channels. For example, assuming the single-tone carrier signal is located on channel 36 in Bluetooth communication, the reflected signal could be located on channel 39 in Bluetooth communication.

[0020] In this scheme, by setting the passive tag to perform frequency shifting processing when reflecting the single-tone carrier signal, the reflected signal and the single-tone carrier signal can be located in different channels, thereby avoiding interference of the single-tone carrier signal on the reflected signal and ensuring that the reflected signal sent by the passive tag can be effectively received.

[0021] In one possible implementation, the channel where the reflected signal is located is a channel selected by the passive tag within a preset channel range, which includes multiple different channels.

[0022] In this scheme, by setting a preset channel range, the passive tag can select a channel for the reflected signal within the preset channel range, thereby ensuring that different passive tags can use different channels to send reflected signals, avoiding mutual interference between the reflected signals sent by different passive tags, and thus ensuring that the reflected signals sent by each passive tag can be received normally.

[0023] In one possible implementation, the passive tag is fully charged when the voltage of the energy storage capacitor in the passive tag exceeds a threshold value.

[0024] Secondly, a passive communication method is provided, applied to a first communication device. This passive communication method includes: the first communication device receiving an excitation signal sent by a second communication device, the excitation signal being used to charge a passive tag; after the excitation signal is interrupted, the first communication device sending a single-tone carrier signal, the single-tone carrier signal being reflected by the passive tag to obtain a reflected signal. Furthermore, based on the cooperation of the first and second communication devices, the sensing of the passive tag can be achieved at a lower cost, avoiding the use of dedicated readers, improving the applicability of the passive tag, and expanding the application scenarios of the passive tag.

[0025] In this scheme, by setting the first communication device to receive the excitation signal and trigger the transmission of a single-tone carrier signal based on whether the excitation signal is interrupted, the passive tag can reflect the single-tone carrier signal after it is fully charged and the excitation signal is interrupted. This enables the first communication device, the second communication device and the passive tag to work synchronously, ensuring the normal sensing of the passive tag and increasing the sensing distance of the passive tag.

[0026] Furthermore, since this solution uses a first communication device and a second communication device to transmit single-tone carrier signals and receive reflected signals from passive tags respectively, the two actions of transmitting single-tone carrier signals and receiving reflected signals can be separated into two independent communication devices. The design of triggering the transmission of single-tone carrier signals based on whether the excitation signal is interrupted ensures the synchronous operation between the two independent communication devices. This solves the problem of high device cost caused by entrusting the transmission and reception of signals to the same device (such as an RFID reader) at the same time. This ensures that this solution can be completed by cooperating with two simple communication devices, effectively expanding the application scenarios of the solution.

[0027] In one possible implementation, after the first communication device detects that the excitation signal carries preset information and the excitation signal is interrupted, the first communication device sends a single-tone carrier signal.

[0028] In other words, if the excitation signal does not carry preset information, then the first communication device will not trigger the transmission of a single-tone carrier signal.

[0029] In this solution, by setting the first communication device to only trigger the transmission of a single-tone carrier signal after receiving an excitation signal containing preset information, the first communication device can only transmit the single-tone carrier signal in specific scenarios (such as when a second communication device authorized by the first communication device sends an excitation signal), thus avoiding the first communication device from frequently triggering the transmission of the single-tone carrier signal and ensuring the security of the communication process.

[0030] In one possible implementation, the first communication device sends a first message to the second communication device. The first message includes preset information and is used to instruct the second communication device to send an excitation signal carrying the preset information. Thus, after receiving the first message, the second communication device can carry the preset information in the excitation signal when sending it.

[0031] In one possible implementation, the preset information includes information about the passive label.

[0032] In one possible implementation, the first communication device and the second communication device reside on different devices. For example, the first communication device may be located on a wireless access point (AP), while the second communication device may be located on a smartphone. Alternatively, the first communication device may be located on a smartwatch, while the second communication device may be located on a smartphone.

[0033] In one possible implementation, both the first and second communication devices are wireless communication modules, and they are integrated into the same device. For example, the first communication device is a Bluetooth module and the second communication device is a Wi-Fi module; or, the second communication device is a Bluetooth module and the first communication device is a Wi-Fi module.

[0034] Thirdly, a passive communication method is provided, applied to a second communication device. The passive communication method includes: the second communication device transmitting an excitation signal to power a passive tag; after ceasing to transmit the excitation signal, the second communication device receiving a reflected signal transmitted by the passive tag, the reflected signal indicating information about the passive tag, and the reflected signal being emitted by the passive tag through reflection of a single-tone carrier signal.

[0035] In one possible implementation, the excitation signal carries preset information.

[0036] In one possible implementation, the second communication device receives a first message sent by the first communication device. The first message includes preset information and is used to instruct the second communication device to send an excitation signal carrying the preset information.

[0037] In one possible implementation, the preset information includes information about the passive label.

[0038] Fourthly, a passive communication method is provided, applied to a first communication device. The passive communication method includes: the first communication device transmitting an excitation signal to charge a passive tag; and after interrupting the transmission of the excitation signal, the first communication device transmitting a single-tone carrier signal, which is reflected by the passive tag to obtain a reflected signal.

[0039] In one possible implementation, the excitation signal includes preset information, and the method further includes: a first communication device sending a second message to a second communication device, the second message including the preset information, and the second message being used to instruct the second communication device to start receiving the reflected signal after receiving the excitation signal including the preset information.

[0040] In one possible implementation, the first communication device receives information about a passive tag sent by the second communication device, the information of which is obtained by the second communication device by receiving reflected signals; in response to whether the passive tag information is included or not in a preset information list, the first communication device sends a prompt message, the prompt message indicating whether the target item has been found or not, the preset information list indicating information about multiple passive tags.

[0041] Fifthly, a passive communication method is provided, applied to a second communication device, the passive communication method comprising: the second communication device receiving an excitation signal for energizing a passive tag; after the excitation signal is interrupted, the second communication device receiving a reflected signal sent by the passive tag for indicating information of the passive tag, wherein the reflected signal is emitted by the passive tag by reflecting a single-tone carrier signal.

[0042] In one possible implementation, the excitation signal includes preset information, and the method further includes: a second communication device receiving a second message sent by a first communication device, the second message including the preset information, and the second message being used to instruct the second communication device to start receiving a reflected signal after receiving an excitation signal including the preset information.

[0043] In one possible implementation, the method further includes: a second communication device parsing the reflected signal to obtain information about the passive tag; in response to whether the passive tag information is included or not in a preset information list, the second communication device sending a prompt message, the prompt message indicating whether the target item has been found or not, and the preset information list indicating information about multiple passive tags.

[0044] In a sixth aspect, a passive tag is provided, including a transceiver module and an energy storage unit, wherein the transceiver module and the energy storage unit cooperate to enable the passive tag to perform the method of any implementation of the first aspect.

[0045] In a seventh aspect, a first communication device is provided, which is used to perform the method of any implementation of the second or fourth aspect.

[0046] Eighthly, a second communication device is provided, which is used to perform the method of any implementation of the third or fifth aspect.

[0047] Ninth aspect, a passive communication system is provided, including a passive tag as in the sixth aspect, a first communication device as in the seventh aspect, and a second communication device as in the eighth aspect.

[0048] Based on the implementation methods provided in the above aspects, this application can be further combined to provide more implementation methods. Attached Figure Description

[0049] Figure 1 is a schematic diagram of the architecture of a passive communication system provided in this application;

[0050] Figure 2 is a flowchart illustrating a passive communication method provided in this application;

[0051] Figure 3 is a schematic diagram of the working state and capacitor charge curve of a passive tag provided in this application;

[0052] Figure 4 is a schematic diagram of the architecture of a passive communication system provided in this application;

[0053] Figure 5 is a schematic diagram of a corporate asset inventory scenario provided in this application;

[0054] Figure 6 is a schematic diagram of the communication process between a smartphone, an optical modem, and a passive tag provided in this application;

[0055] Figure 7 is a schematic diagram of a passive communication system provided in this application operating in multiple working cycles;

[0056] Figure 8 is a schematic diagram of different passive tags transmitting reflected signals at staggered times according to this application;

[0057] Figure 9 is a flowchart illustrating another passive communication method provided in this application;

[0058] Figure 10 is a schematic diagram of the architecture of another passive communication system provided in this application;

[0059] Figure 11 is a schematic diagram of the communication process between a smartphone, a smartwatch, and a passive tag provided in this application;

[0060] Figure 12 is a schematic diagram of the architecture of another passive communication system provided in this application;

[0061] Figure 13 is a schematic diagram of a communication process between a smartphone and a passive tag provided in this application. Detailed Implementation

[0062] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0063] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0064] For ease of understanding, some technical terms involved in the embodiments of this application will be introduced below.

[0065] (1) Radio Frequency Identification (RFID)

[0066] RFID is a type of automatic identification technology and a typical example of passive Internet of Things (IoT). Specifically, RFID is a wireless communication technology that mainly consists of a reader and an electronic tag. The reader can identify a specific target (such as an electronic tag) and read and write related data through radio signals without establishing mechanical or optical contact with the specific target.

[0067] In this system, radio signals transmit data from tags attached to objects via electromagnetic fields tuned to radio frequencies, enabling automatic identification and tracking. Some electronic tags draw power from the electromagnetic field emitted by the reader during identification, eliminating the need for batteries; others are self-powered and actively emit radio waves (electromagnetic fields tuned to radio frequencies). Electronic tags contain electronically stored information and can be identified within a range of several meters. Unlike barcodes, electronic tags do not need to be within the reader's line of sight and can be embedded within the object being tracked.

[0068] Specifically, when an electronic tag enters the magnetic field emitted by a reader, it receives the radio frequency signal emitted by the reader and uses the energy obtained from the induced current to send out the product information stored in the chip, or actively sends a signal of a certain frequency. In this way, the reader reads and decodes the information sent by the electronic tag and sends it to the system's information processing center for corresponding data processing.

[0069] Specifically, RFID uses radio waves to exchange and store information without physical contact. It combines wireless communication with data access technology, then connects to a database system to achieve contactless, two-way communication, thus achieving identification and data exchange, forming an extremely complex system. Generally, based on communication distance, RFID systems can be divided into near-field and far-field systems. Correspondingly, the data exchange methods between the reader / writer and the electronic tag are classified as load modulation and backscatter modulation.

[0070] Currently, RFID is widely used, with typical applications including animal microchips, car microchip anti-theft devices, access control, parking management, production line automation, and material management.

[0071] (2) Single-tone carrier

[0072] A single-tone carrier, also known as a single-carrier modulation technique, refers to a modulation technique that uses only one carrier wave within a fixed frequency band. A single-tone carrier signal is a signal transmitted based on single-tone carrier technology.

[0073] The applicant's research revealed that current RFID tags simultaneously collect the radio electromagnetic wave energy emitted by the RFID reader and transmit signals back to the RFID tag. In other words, RFID collects electromagnetic wave energy while simultaneously using that energy to send signals. Because the amount of radio electromagnetic wave energy collected by an RFID tag in a short period is relatively small, the signal strength transmitted by the RFID tag is weak. This means that the RFID reader can only receive the signal when it is relatively close to the RFID tag, affecting its application. For example, an RFID reader often can only sense an RFID tag when it is very close, thus limiting the application scenarios of RFID tags.

[0074] In view of this, this application provides a passive communication method. First, an excitation signal is sent to the passive tag to charge it. After the passive tag is fully charged, a single-tone carrier signal is sent to it, enabling the passive tag to reflect the single-tone carrier signal and transmit a reflected signal carrying identification information. Because the passive tag is first charged by the excitation signal and then reflects the single-tone carrier signal to transmit the reflected signal, it has sufficient energy to transmit the reflected signal, ensuring that the reflected signal can be transmitted over a longer distance. This effectively increases the sensing range of the passive tag and allows it to be used in more scenarios.

[0075] Furthermore, current RFID readers need to simultaneously send radio electromagnetic wave signals to and receive signals sent by RFID tags in order to identify the tag's information. In other words, the RFID reader needs to perform simultaneous signal transmission and reception. In this situation, the radio electromagnetic wave signals sent by the RFID reader often interfere with the signals received by the RFID tag. Therefore, RFID readers often need to solve complex signal processing problems, such as eliminating interference between the transmitted radio electromagnetic wave signals and the signals sent by the RFID tag. This results in higher costs for RFID readers and limits the need for dedicated RFID readers to read RFID tags.

[0076] Please refer to Figure 1, which is a schematic diagram of the architecture of a passive communication system provided in this application. As shown in Figure 1, the passive communication system includes a passive tag, a first communication device, and a second communication device. During the operation of the passive communication system, one of the first and second communication devices sends an excitation signal to the passive tag, thereby charging the passive tag. After the passive tag is fully charged, one of the first and second communication devices sends a single-tone carrier signal to the passive tag, which is reflected by the passive tag to send a reflected signal; and the other communication device receives the reflected signal sent by the passive tag to obtain the identifier sent by the passive tag.

[0077] For passive tags, the circuit structure can be adjusted based on existing RFID tags. Specifically, a small energy storage unit (such as a capacitor) can be included in the passive tag to store the energy gained by the passive tag from receiving the excitation signal. Furthermore, a synchronization signal processing circuit can be included in the passive tag so that after charging is complete and the excitation signal is detected to be interrupted, the passive tag can begin receiving a single-tone carrier signal, thereby transmitting a reflected signal by reflecting the single-tone carrier signal.

[0078] Please refer to Figure 2, which is a flowchart illustrating a passive communication method provided in this application.

[0079] Step 201: The second communication device sends an excitation signal, which is used to charge the passive tag.

[0080] In this application, the excitation signal is specifically used to power the passive tag. That is, after receiving the excitation signal, the passive tag can acquire the energy from the excitation signal and store the energy. Specifically, the excitation signal can be any type of electromagnetic wave signal, as long as it can power the passive tag.

[0081] Furthermore, due to regulatory constraints, communication devices cannot continuously transmit excitation signals for extended periods. Therefore, the second communication device in this application can transmit excitation signals intermittently. That is, after each continuous transmission of an excitation signal for a certain duration, the second communication device will interrupt the transmission for a period of time before resuming transmission. For example, the duration of each continuous transmission of the excitation signal by the second communication device is 2 milliseconds (ms), and after interrupting the transmission, the second communication device will resume transmission after an 8-millisecond interval.

[0082] Optionally, before the second communication device sends the excitation signal, the first and second communication devices may negotiate the excitation signal so that the excitation signal sent by the second communication device can include the information negotiated by the first and second communication devices.

[0083] For example, the first communication device sends a first message to the second communication device. The first message includes preset information and is used to instruct the second communication device to send an excitation signal carrying the preset information. Thus, after receiving the first message, the second communication device can carry the preset information in the excitation signal when sending it.

[0084] The preset information in the excitation signal may include information about the passive tag (such as the identifier of the passive tag).

[0085] Step 202: The passive tag receives the excitation signal and charges itself based on the received excitation signal.

[0086] After the second communication device begins sending an excitation signal, the passive tag can receive the excitation signal and obtain energy through it. For example, during the process of receiving the excitation signal, the circuit structure in the passive tag can obtain electrical energy based on the principle of electromagnetic induction. When the passive tag obtains energy, it stores the energy obtained from the excitation signal to recharge the passive tag.

[0087] Optionally, the charging process for the passive tag can specifically involve storing the acquired electrical energy in a preset energy storage unit, such as one or more energy storage capacitors. In this way, after the passive tag is charged through the energy storage unit, the electrical energy in the energy storage unit can provide power for the passive tag's operation when the passive tag needs to work.

[0088] Step 203: After the excitation signal is interrupted, the first communication device sends a single-tone carrier signal, which is used to be reflected by the passive tag to obtain a reflected signal.

[0089] It is understood that the excitation signal transmitted by the second communication device propagates through the air wirelessly, therefore the first communication device can also receive the excitation signal transmitted by the first communication device. Since the second communication device transmits the excitation signal intermittently, the first communication device can begin transmitting a single-tone carrier signal after detecting an interruption in the excitation signal transmitted by the second communication device. This single-tone carrier signal is used to be received and reflected by the passive tag, thereby enabling the passive tag to transmit signals with low power consumption.

[0090] In this application, to facilitate the passive tag's ability to reflect signals based on a single-tone carrier signal, the original data in the single-tone carrier signal transmitted by the first communication device can specifically be continuous 0s or 1s. Thus, the passive tag can transmit 0s or 1s by reflecting or not reflecting the single-tone carrier signal, thereby achieving the transmission of reflected signals.

[0091] Optionally, during the process of receiving the excitation signal, the first communication device can parse and obtain the information carried in the excitation signal to detect whether the excitation signal carries preset information. After the first communication device detects that the excitation signal carries preset information and the excitation signal is interrupted, the first communication device then sends a single-tone carrier signal. That is, triggering the first communication device to send a single-tone carrier signal requires two conditions to be met: one condition is that the first communication device detects that the excitation signal carries preset information, and the other condition is that the excitation signal is interrupted.

[0092] In this solution, by setting the first communication device to only trigger the transmission of a single-tone carrier signal after receiving an excitation signal containing preset information, the first communication device can only transmit the single-tone carrier signal in specific scenarios (such as when a second communication device authorized by the first communication device sends an excitation signal), thus avoiding the first communication device from frequently triggering the transmission of the single-tone carrier signal and ensuring the security of the communication process.

[0093] Step 204: After the passive tag is fully charged, the passive tag receives a single-tone carrier signal.

[0094] In this application, the passive tag only enters the working state to receive single-tone carrier signals after it has been fully charged. If the passive tag is not fully charged, it will not enter the working state, meaning it will not receive single-tone carrier signals. For example, the passive tag may include a voltage detection circuit to detect the voltage of the energy storage capacitor within the tag. When the voltage detection circuit detects that the voltage of the energy storage capacitor in the passive tag exceeds a threshold value (e.g., 1.3 volts), the passive tag can be considered fully charged.

[0095] Optionally, when the second communication device intermittently transmits excitation signals, to facilitate synchronous operation between the first communication device, the second communication device, and the passive tag, the passive tag may only begin operating and receiving single-tone carrier signals after it has been fully charged and an interruption of the excitation signal is detected. That is, the passive tag needs to meet two conditions to begin operating: one is that it has been fully charged, and the other is that an interruption of the excitation signal is detected. For example, the passive tag may detect an interruption of the excitation signal by detecting a falling edge of the excitation signal.

[0096] Furthermore, it should be noted that when the second communication device intermittently transmits excitation signals, the number of excitation signals continuously transmitted by the second communication device within one cycle may not be sufficient to fully charge the passive tag. Therefore, the passive tag may receive multiple intermittent excitation signals from the second communication device before it is fully charged. For example, if the second communication device only continuously transmits an excitation signal for 2ms each time, the passive tag may not be fully charged after receiving the 2ms excitation signal for the first time. In this case, the passive tag will wait for the second communication device to transmit the next excitation signal and continue charging, and so on, until the passive tag is fully charged.

[0097] For example, please refer to Figure 3, which is a schematic diagram of the working state and capacitor charge curve of a passive tag provided in this application. As shown in Figure 3, the second communication device continuously sends an excitation signal for 2ms each time, and waits 8ms after interrupting the transmission of the excitation signal before retransmitting it. Therefore, during each period when the second communication device transmits the excitation signal, the passive tag wirelessly charges (i.e., charges the energy storage capacitor). After the second communication device interrupts the transmission of the excitation signal, the charge of the energy storage capacitor in the passive tag decreases slightly until the second communication device continues to transmit the excitation signal. Based on this, by continuously receiving excitation signals for charging, the passive tag can be fully charged during the 5th reception of the excitation signal, and after being fully charged, it begins to detect the falling edge of the excitation signal. After detecting the falling edge of the excitation signal, the passive tag can transmit a reflected signal by reflecting the received single-tone carrier signal.

[0098] Optionally, in some cases, the excitation signal may carry first information, which may be information indicating the passive tag that the first or second communication device wants to find. In this way, after the passive tag is fully charged, it parses the excitation signal to obtain the first information indicated in the excitation signal. Furthermore, if the first information matches the information of the passive tag, the passive tag then triggers the reception of a single-tone carrier signal. That is, if the first information in the excitation signal does not match the information of the passive tag, the passive tag will not trigger the reception of the single-tone carrier signal, thus avoiding signal reflection and ensuring that the first or second communication device can find the specific passive tag.

[0099] Step 205: The passive tag reflects the single-tone carrier signal to send a reflected signal, which is used to indicate information about the passive tag.

[0100] During the reception of a single-tone carrier signal, a passive tag can selectively reflect data in the single-tone carrier signal based on its information (such as the tag's identifier), thereby transmitting a reflected signal that indicates the information of the passive tag.

[0101] Optionally, to avoid interference from the single-tone carrier signal to the reflected signal and to ensure that the reflected signal sent by the passive tag can be effectively received, the passive tag can perform frequency shifting processing when reflecting the single-tone carrier signal, thereby placing the reflected signal and the single-tone carrier signal on different channels. For example, assuming the single-tone carrier signal is located on channel 36 in Bluetooth communication, the reflected signal could be located on channel 39 in Bluetooth communication. Specifically, to achieve frequency shifting, the passive tag can be equipped with a signal reflection frequency shifting processing circuit, which can reflect the single-tone carrier signal to obtain a reflected signal located on a different channel than the single-tone carrier signal.

[0102] Step 206: After interrupting the transmission of the excitation signal, the second communication device receives and parses the reflected signal transmitted by the passive tag to obtain the information of the passive tag.

[0103] The reflected signal is used to indicate information about the passive tag, and it is emitted by the passive tag by reflecting a single-tone carrier signal. Since it is often difficult for a single communication device to simultaneously transmit a single-tone carrier signal and receive a reflected signal, in this application, a first communication device transmits the single-tone carrier signal, and a second communication device receives the reflected signal transmitted by the passive tag. Furthermore, since the first communication device only begins transmitting the single-tone carrier signal after detecting that the second communication device has interrupted transmitting the excitation signal, and the passive tag only begins reflecting the signal after the excitation signal is interrupted, the second communication device can begin receiving the reflected signal transmitted by the passive tag only after interrupting the transmission of the excitation signal, thereby achieving synchronous cooperation between the first communication device, the second communication device, and the passive tag.

[0104] After receiving the reflected signal, the second communication device can analyze it to obtain information about the passive tag indicated by the reflected signal (such as the tag's identifier). Therefore, after receiving and analyzing the reflected signal, the second communication device can acquire the information of the passive tag and perform subsequent processing according to the application scenario. For example, in a lost item scenario, a passive tag is attached to the item being searched. When the second communication device receives the reflected signal from the passive tag and acquires its information, it indicates that the passive tag is near the second communication device. Therefore, the second communication device can send a notification message (such as a voice message or text message) to the user to indicate the area around the passive tag.

[0105] In this application, since the first communication device and the second communication device cooperate to charge the passive tag and acquire its information, by using the time when the second communication device interrupts sending the excitation signal as the time when the passive tag enters operation and the first communication device sends a single-tone carrier signal, the synchronization between the first communication device, the second communication device, and the passive tag can be well achieved. This ensures that the passive tag can immediately perform signal reflection after entering operation, improves the working efficiency of the passive tag, and avoids wasting the energy of the passive tag.

[0106] Furthermore, since this solution uses a first communication device and a second communication device to transmit single-tone carrier signals and receive reflected signals from passive tags respectively, the two actions of transmitting single-tone carrier signals and receiving reflected signals can be separated into two independent communication devices. The design of triggering the transmission of single-tone carrier signals based on whether the excitation signal is interrupted ensures the synchronous operation between the two independent communication devices. This solves the problem of high device cost caused by entrusting the transmission and reception of signals to the same device (such as an RFID reader) at the same time. This ensures that this solution can be completed by cooperating with two simple communication devices, effectively expanding the application scenarios of the solution.

[0107] In this application, there are various specific implementations of the first communication device and the second communication device.

[0108] In implementation method 1, both the first communication device and the second communication device are wireless communication modules, and the first communication device and the second communication device are integrated on the same device.

[0109] The first communication device and the second communication device are the same type of wireless communication module, such as Bluetooth module, Wi-Fi module, Zigbee communication module, Long Range Radio (LoRa) module, Narrow Band Internet of Things (NB-IoT) communication module or Near Link communication module.

[0110] Furthermore, the first communication device and the second communication device can also be different types of wireless communication modules, such as the first communication device being a Bluetooth module and the second communication device being a Wi-Fi module; or, the second communication device being a Bluetooth module and the first communication device being a Wi-Fi module. In short, this application does not limit the specific hardware implementation of the first communication device and the second communication device.

[0111] Furthermore, the first and second communication devices can be integrated into the same device. For example, the first and second communication devices can be integrated into the same smartphone, access point (AP), robot, smart car, smartwatch, or other device. This application does not limit the device into which the first and second communication devices are integrated. The AP can include, for example, an optical modem, router, base station, gateway, or switch. It should be noted that when the first and second communication devices are integrated into the same device, since both devices need to simultaneously transmit single-tone carrier signals and receive reflected signals from passive tags, the device often needs to be equipped with two antennas to allow the first and second communication devices to operate simultaneously.

[0112] In implementation method 2, the first communication device and the second communication device are located on different devices.

[0113] In implementation method 2, the first and second communication devices can still be wireless communication modules, but they are located on different devices. For example, the first communication device is located on the access point (AP), while the second communication device is located on a smartphone. Alternatively, the first communication device may be located on a smartwatch, while the second communication device is located on a smartphone.

[0114] For ease of understanding, the following will take the Bluetooth module located on the optical modem as the first communication device and the Bluetooth module located on the smartphone as the second communication device as an example to introduce in detail the application process of the passive communication method provided in this application in a real-world scenario.

[0115] For example, please refer to Figure 4, which is a schematic diagram of the architecture of a passive communication system provided in this application. As shown in Figure 4, the first communication device mentioned above is, for example, a Bluetooth module built into an optical modem, and the second communication device mentioned above is, for example, a Bluetooth module built into a smartphone. The passive tag has a built-in energy storage capacitor.

[0116] In this process, the Bluetooth module in the smartphone first sends an excitation signal to enable the passive tag to charge the energy storage capacitor. Then, the Bluetooth module in the optical modem sends a single-tone carrier signal, which the passive tag reflects to send a reflected signal. During the passive tag's signal transmission, the Bluetooth module in the smartphone receives the reflected signal to parse and obtain the passive tag's information.

[0117] The passive communication system architecture shown in Figure 4 can be applied to enterprise asset management scenarios. Specifically, enterprises often have many assets (such as computers, displays, printers, conference tablets, office supplies, etc.) that require regular management. Currently, enterprises manage assets by attaching RFID tags to them and having dedicated personnel use barcode scanners (i.e., RFID readers) to manually inventory and record each asset, which is labor-intensive and prone to omissions. Based on the passive communication system architecture shown in Figure 4, passive tags can be attached to assets, and combined with optical modems and smartphones, automatic asset inventory can be achieved, improving inventory efficiency and avoiding omissions. For example, in a specific implementation scenario, combined with the optical modems deployed within the enterprise, automatic asset inventory can be achieved within a 1-meter coverage area of ​​a smartphone.

[0118] Please refer to Figure 5, which is a schematic diagram of an enterprise asset inventory scenario provided in this application. As shown in Figure 5, in a possible enterprise asset inventory scenario, the enterprise's internal environment includes a reception area and an office area, with the office area including one or more offices and meeting rooms. Various assets within the enterprise are affixed with passive tags, and one or more optical modems are deployed in the enterprise's internal environment (such as the main optical modem deployed at the reception area and the secondary optical modem deployed in the meeting room, as shown in Figure 5). Furthermore, the enterprise's office staff typically carry smartphones. In this scenario, the optical modems, smartphones, and passive tags in the enterprise's internal environment constitute the passive communication system shown in Figure 4.

[0119] Furthermore, the architecture of the passive communication system shown in Figure 4 can also be applied to home item-finding scenarios. Currently, in a user's home, when they need to find an item (such as clothing, toys, books, etc.), they can only rely on their eyes, which is inefficient and difficult to achieve when there are many items. Based on the architecture of the passive communication system shown in Figure 4, passive tags can be attached to items in the home, and combined with an optical modem and a smartphone, automatic item finding can be achieved, improving the efficiency of users finding items. For example, in a specific implementation scenario, combined with an optical modem deployed in the user's home, it is possible to find items within a 1-meter range of the smartphone. That is, the user can walk around the home with a smartphone to find items, and if the passive tag attached to the item is within 1 meter of the smartphone, the smartphone can obtain the information from the passive tag and then notify the user that the corresponding item has been found.

[0120] Please refer to Figure 6, which is a schematic diagram of the communication process between a smartphone, an optical modem, and a passive tag provided in this application. As shown in Figure 6, the communication process between the smartphone, the optical modem, and the passive tag includes the following steps 601-607.

[0121] Step 601: The smartphone sends a lost item request message to the optical modem.

[0122] In asset inventory or home item retrieval scenarios, a smartphone can send a retrieval request message to the optical modem via an application or other means. This message requests the optical modem to cooperate with the smartphone to begin searching for the item, thereby completing the asset inventory or home item retrieval. Optionally, the retrieval request message may carry preset information, which instructs the optical modem to send a single-tone carrier signal only after receiving an excitation signal carrying the preset information.

[0123] Step 602: The optical modem sends a lost item negotiation message to the smartphone.

[0124] Upon receiving a lost item request message, the optical modem can send a lost item negotiation message (i.e., the first message mentioned above) to the smartphone. This message indicates that the optical modem is ready to execute the lost item process. Optionally, the lost item negotiation message may carry preset information, and this message is used to instruct the smartphone to send an excitation signal carrying the preset information. This preset information may include, for example, specific sequence information, such as the smartphone's Media Access Control Address (MAC) address or sequence information randomly generated by the optical modem. This application does not specifically limit the content of the preset information.

[0125] Optionally, in some embodiments, asset inventory or finding items within the home can also be initiated by the optical modem. That is, the smartphone no longer needs to perform step 601 as described above; the optical modem can directly send a finding negotiation message to the smartphone.

[0126] Step 603: The smartphone sends an excitation signal to the passive tag.

[0127] Optionally, the excitation signal sent by the smartphone may include preset information.

[0128] Step 604: The optical modem receives and parses the excitation signal, and the passive tag receives the excitation signal and charges.

[0129] During the process of the smartphone sending the excitation signal, the optical modem continuously receives and parses the excitation signal to obtain the preset information carried in the excitation signal. The passive tag receives the excitation signal and charges the energy storage capacitor based on the received excitation signal.

[0130] Step 605: The optical modem sends a single-tone carrier signal.

[0131] If the optical modem detects that the excitation signal contains preset information, it can start sending a single-tone carrier signal after detecting an interruption in the excitation signal, so that the passive tag can reflect the single-tone carrier signal.

[0132] Step 606: The passive tag sends a reflected signal by reflecting a single-tone carrier signal.

[0133] After the passive tag is fully charged and an interruption of the excitation signal is detected, the passive tag can start and enter the working state, thereby receiving and reflecting single-tone carrier signals, and then sending reflected signals. The reflected signals sent by the passive tag may include the tag's identifier.

[0134] It should be noted that passive tags often require a certain amount of time to activate and enter the working state; for example, it may take 1.5-3ms. Furthermore, due to regulatory constraints, the optical modem cannot continuously transmit single-tone carrier signals (for example, the maximum duration for which an optical modem can continuously transmit a single-tone carrier signal is 2ms). Therefore, to ensure that the time period for the optical modem to transmit the single-tone carrier signal matches as closely as possible with the time period for the passive tag to enter the working state, the optical modem waits for a set duration after detecting an interruption in the excitation signal before starting to transmit the single-tone carrier signal. This set duration can be less than or equal to the time required for the passive tag to activate and enter the normal working state. For example, assuming the time required for the passive tag to activate and enter the normal working state is t1, and t1 is 1.5ms, and the set duration for the optical modem to wait is t2, then t2 could be, for example, 1ms.

[0135] Step 607: The smartphone receives and analyzes the reflected signal to obtain information about the passive tag.

[0136] After the smartphone stops sending excitation signals, it can enter a state of receiving reflected signals, thereby receiving and parsing the reflected signals sent by the passive tags to obtain the passive tag information. In this way, by working together with a smartphone and an optical modem, information about passive tags within a certain distance range of the smartphone can be obtained on the smartphone, thus enabling asset inventory.

[0137] It should be noted that in the above embodiments, the passive tag only begins to operate after detecting an interruption in the excitation signal; the optical modem also only begins to transmit a single-tone carrier signal after detecting an interruption in the excitation signal. Because the reflected signal transmitted by the passive tag is received by the smartphone, if the passive tag and optical modem start operating while the smartphone is still transmitting the excitation signal, the smartphone will miss receiving the reflected signal, leading to communication failure. Therefore, in this application, by setting the passive tag and optical modem to only start operating after detecting an interruption in the excitation signal, synchronous operation between the smartphone, optical modem, and passive tag can be achieved, ensuring that the reflected signal can be accurately received.

[0138] Furthermore, steps 601-607 described above are actually the steps performed by the passive communication system within one working cycle. In practical applications, the passive communication system operates for multiple working cycles, and steps 601-607 are repeated in each working cycle. It is worth noting that in some working cycles, if the passive tag has not yet been fully charged, the passive tag will not perform the process of reflecting the single-tone carrier signal, and therefore the smartphone will not receive the reflected signal.

[0139] For example, please refer to Figure 7, which is a schematic diagram of a passive communication system provided in this application operating in multiple working cycles. As shown in Figure 7, the total duration of working cycle N and working cycle N+1 is 2ms + 8ms = 10ms. During working cycle N and working cycle N+1, the smartphone sends an excitation signal to enable the passive tag to charge based on the excitation signal, while the optical modem parses the excitation signal. After the excitation signal is interrupted, the passive tag needs to consume time t1 to enter the working state, while the optical modem waits for time t2 (t2 is less than or equal to t1) before sending a single-tone carrier signal, so that the passive tag entering the working state can send a reflected signal by reflecting the single-tone carrier signal. In this way, the smartphone can also receive the reflected signal after the passive tag starts working.

[0140] The above describes a scenario for asset inventory based on smartphones, optical modems, and passive tags. Generally, in an asset inventory scenario, multiple passive tags may exist simultaneously within a certain distance of the smartphone. These passive tags will receive excitation signals from the smartphone, enter an operational state, and then transmit reflected signals. If each passive tag transmits its reflected signal at the same time and the reflected signals are all on the same channel, mutual interference may occur between the reflected signals transmitted by multiple passive tags, thus affecting the smartphone's ability to properly receive the reflected signals from each passive tag.

[0141] Based on this, the present application may use time staggering or channel staggering to avoid mutual interference between different reflected signals, and ensure that the reflected signals sent by different passive tags are received normally as much as possible.

[0142] In the first implementation method, the transmission times of the reflected signals are staggered.

[0143] For example, for some passive tags, after the passive tag begins receiving a single-tone carrier signal (i.e., enters the working state), the passive tag may reflect the single-tone carrier signal after a target delay. Then, for other passive tags, these tags may reflect the single-tone carrier signal immediately after starting to receive it, without needing a certain delay. This allows the timing of reflected signals sent by different passive tags to be staggered, avoiding mutual interference between reflected signals.

[0144] Optionally, in scenarios where many passive tags simultaneously enter the working state, the target duration for the passive tag's delayed reflection of the single-tone carrier signal can be n times a preset duration, where n is an integer selected by the passive tag within a preset integer range, which includes multiple different integers. The preset duration can be, for example, 100 microseconds (μs) or 200 μs. For instance, if the preset integer range is [1, 10] (i.e., the preset integer range includes 10 integers), then the passive tag can randomly select an integer n within this range to determine the target duration.

[0145] In this way, by setting the target duration of the passive tag's delayed reflection of the single-tone carrier signal to n times the preset duration, the passive tag can randomly select the duration of the delayed reflection of the single-tone carrier signal within a certain range, thereby ensuring that the times when most passive tags send reflected signals are staggered as much as possible, and guaranteeing that the reflected signals sent by each passive tag can be received normally.

[0146] For example, please refer to Figure 8, which is a schematic diagram of different passive tags transmitting reflected signals at staggered times according to this application. As shown in Figure 8, the passive communication system includes passive tags 1 to 4, and each passive tag requires a time t1 to enter the normal working state after the excitation signal is interrupted. At this time, passive tag 1 may reflect a single-tone carrier signal immediately after entering the working state, without delaying the reflection of the single-tone carrier signal, so that the reflected signal carrying the identifier of passive tag 1 begins to be transmitted after time t1 after the excitation signal is interrupted. Passive tag 2 may reflect a single-tone carrier signal after a delay of x time (where x is, for example, 200 μs) after entering the working state, so that the reflected signal carrying the identifier of passive tag 1 begins to be transmitted after time t1+x after the excitation signal is interrupted. Similarly, passive tag 3 may reflect a single-tone carrier signal after a delay of 2x time after entering the working state, so that the reflected signal carrying the identifier of passive tag 1 begins to be transmitted after time t1+2x after the excitation signal is interrupted. In this way, although the passive communication system includes multiple passive tags, the reflected signals sent by each passive tag are staggered, and the phenomenon of reflected signal collision is not easy to occur, ensuring that the smartphone can receive the reflected signals sent by each passive tag normally.

[0147] The second implementation method involves staggering the transmission channels of the reflected signals.

[0148] For example, for a passive tag, the channel on which the reflected signal transmitted by the passive tag is located is a channel selected by the passive tag within a preset channel range, which includes multiple different channels. Furthermore, the channels included in the preset channel range are not the same as the channel on which the single-tone carrier signal is located. For instance, assuming the single-tone carrier channel is located on channel X, the preset channel range can include M channels before channel X and M channels after channel X.

[0149] In this way, when a passive tag reflects a single-tone carrier signal, it randomly selects a channel within a preset channel range and then transmits the reflected signal on the selected channel. Of course, a passive tag can also select a channel within the preset channel range based on other methods, such as selecting the appropriate channel based on information such as the passive tag's identifier.

[0150] In this scheme, by setting a preset channel range, the passive tag can select a channel for the reflected signal within the preset channel range, thereby ensuring that different passive tags can use different channels to send reflected signals, avoiding mutual interference between the reflected signals sent by different passive tags, and thus ensuring that the reflected signals sent by each passive tag can be received normally.

[0151] The above embodiments illustrate a scenario where one communication device transmits an excitation signal and receives a reflected signal, while another communication device transmits a single-tone carrier signal. In other embodiments, the same communication device may transmit both the excitation signal and the single-tone carrier signal, while another communication device receives the reflected signal.

[0152] Please refer to Figure 9, which is a flowchart illustrating another passive communication method provided in this application. As shown in Figure 9, the passive communication method includes the following steps 901-908.

[0153] Step 901: The first communication device sends an excitation signal, which is used to charge the passive tag.

[0154] Step 902: The second communication device receives and parses the excitation signal, and the passive tag receives the excitation signal and charges itself based on the received excitation signal.

[0155] In this application, steps 901-902 are similar to steps 201-202, and can be referred to steps 201-202 above for details. The difference between steps 901-902 and steps 201-202 is that in step 901, the excitation signal is sent by the first communication device, while in step 201, the excitation signal is sent by the second communication device.

[0156] Furthermore, the second communication device receives and parses the excitation signal in order to subsequently determine whether to enter the working state.

[0157] Step 903: After interrupting the transmission of the excitation signal, the first communication device transmits a single-tone carrier signal, which is used to be reflected by the passive tag to obtain a reflected signal.

[0158] In this application, both the excitation signal and the single-tone carrier signal are transmitted by the first communication device. Since the first communication device transmits the excitation signal intermittently, it can trigger the transmission of the single-tone carrier signal after each interruption of the excitation signal transmission.

[0159] Step 904: After the passive tag is fully charged, the passive tag receives a single-tone carrier signal.

[0160] Step 905: The passive tag reflects the single-tone carrier signal to send a reflected signal, which is used to indicate information about the passive tag.

[0161] Steps 904-905 are similar to steps 204-205 above. Please refer to steps 204-205 above for details.

[0162] Step 906: After the excitation signal is interrupted, the second communication device receives the reflected signal sent by the passive tag. The reflected signal is used to indicate the information of the passive tag, and the reflected signal is emitted by the passive tag by reflecting a single-tone carrier signal.

[0163] In this application, the second communication device may be triggered to start receiving the reflected signal sent by the passive tag after detecting an interruption of the excitation signal, so as to realize the synchronous operation between the first communication device and the second communication device.

[0164] Optionally, the second communication device may also trigger the reception of the reflected signal sent by the passive tag only after detecting that the excitation signal includes preset information and the excitation signal is interrupted.

[0165] Before the first communication device sends an excitation signal, it may send a second message to the second communication device. This second message includes preset information and instructs the second communication device to begin receiving reflected signals after receiving the excitation signal containing the preset information. In other words, the first and second communication devices can negotiate in advance to ensure that the second communication device only begins operation after receiving an excitation signal containing specific information, thus preventing the second communication device from frequently entering a state ready to receive reflected signals.

[0166] Step 907: The second communication device analyzes the reflected signal to obtain information about the passive tag.

[0167] After receiving the reflected signal, the second communication device can analyze the reflected signal and obtain the information of the passive tag. In this way, the second communication device can perform subsequent processing on the passive tag information according to the needs of the actual scenario.

[0168] For example, in a lost-and-found scenario, in response to whether passive tags are included or excluded from a preset information list, the second communication device sends a prompt message indicating whether the target item has been found or not. The preset information list indicates information about multiple passive tags, and the target item is the item to which the aforementioned passive tags are attached.

[0169] Specifically, when the preset information list includes information about a passive tag parsed by the second communication device, it means that the second communication device has found the passive tag indicated by the preset information list. Therefore, the second communication device can send a prompt message (such as a voice message or a text message) to notify the user that a passive tag in the preset information list has been found. At this time, the preset information list can be a list specified by the user to record information about multiple passive tags that the user needs to find.

[0170] Step 908: The second communication device sends information about the passive tag to the first communication device.

[0171] Furthermore, the second communication device can also send information about a passive tag to the first communication device, which then performs further processing based on that information. For example, if the second communication device is located on a smartwatch and the first communication device is located on a smartphone, the second communication device can send the parsed passive tag information to the first communication device, enabling the smartphone to complete the item retrieval process.

[0172] Specifically, after receiving information from a passive tag, in response to whether the passive tag is included or not in a preset information list, the first communication device sends a prompt message to indicate whether the target item has been found or not.

[0173] For ease of understanding, the following will take the Bluetooth module located on a smartphone as the first communication device and the Bluetooth module located on a smartwatch as the second communication device as an example to describe in detail the application process of the passive communication method provided in this application in a real-world scenario.

[0174] For example, please refer to Figure 10, which is a schematic diagram of the architecture of another passive communication system provided in this application. As shown in Figure 10, the first communication device in the embodiment corresponding to Figure 9 is, for example, a Bluetooth module built into a smartphone, and the second communication device mentioned above is, for example, a Bluetooth module built into a smartwatch. The passive tag has a built-in energy storage capacitor.

[0175] In this process, the Bluetooth module in the smartphone first sends an excitation signal to enable the passive tag to charge its energy storage capacitor. Then, after interrupting the excitation signal transmission, the smartphone's Bluetooth module sends a single-tone carrier signal, which the passive tag reflects to send a reflected signal. During this reflection signal transmission, the Bluetooth module in the smartwatch receives the reflected signal, parses it to obtain the passive tag's information, and then sends this information back to the smartphone.

[0176] The passive communication system architecture shown in Figure 4 can be applied to personal item management scenarios. Specifically, users need to manage various personal belongings in different situations, such as frequently checking their luggage, wallets, keys, briefcases, etc., while traveling. In personal item management scenarios, by attaching passive tags to the items to be managed, and through the user's smartphone and smartwatch, information from these tags located around the user can be read. This allows the smartphone to determine whether the managed items are within the user's vicinity. For example, if an item is in a preset item list or not, the smartphone can send a notification message to the user, allowing them to promptly check the item's status and prevent loss.

[0177] Please refer to Figure 11, which is a schematic diagram of the communication process between a smartphone, a smartwatch, and a passive tag provided in this application. As shown in Figure 11, the communication process between the smartphone, smartwatch, and passive tag includes the following steps 1101-1107.

[0178] Step 1101: The smartphone sends a lost item request message to the smartwatch.

[0179] To manage personal belongings, a smartphone can send a lost item request message (i.e., the second message mentioned above) to a smartwatch via an application or other means. This message requests the smartwatch to cooperate with the smartphone to begin searching for the item, thereby completing the management of personal belongings. Optionally, the lost item request message may carry preset information, which instructs the smartwatch to begin receiving reflected signals after receiving an excitation signal carrying the preset information.

[0180] Step 1102: The smartwatch sends a lost item response message to the smartphone.

[0181] After receiving a lost item request message, the smartwatch can send a lost item response message to the smartphone. This lost item negotiation message can indicate that the smartwatch is ready to execute the lost item process.

[0182] Step 1103: The smartphone sends an excitation signal to the passive tag.

[0183] The excitation signal sent by the smartphone includes preset information.

[0184] Step 1104: The smartwatch receives and parses the excitation signal, and the passive tag receives the excitation signal and charges.

[0185] While the smartphone sends the excitation signal, the smartwatch continuously receives and parses the excitation signal to obtain the preset information carried within it. The passive tag receives the excitation signal and charges its energy storage capacitor based on the received signal.

[0186] Step 1105: After interrupting the transmission of the excitation signal, the smartphone transmits a single-tone carrier signal.

[0187] Step 1106: The passive tag sends a reflected signal by reflecting a single-tone carrier signal.

[0188] After the passive tag is fully charged and an interruption of the excitation signal is detected, the passive tag can start and enter the working state, thereby receiving and reflecting single-tone carrier signals, and then sending reflected signals. The reflected signals sent by the passive tag may include the tag's identifier.

[0189] Step 1107: The smartwatch receives and analyzes the reflected signal to obtain information about the passive tag.

[0190] After the smartwatch parses the excitation signal and detects that it contains preset information and that the excitation signal is interrupted, the smartwatch can enter the working state of receiving reflected signals, thereby receiving and parsing the reflected signals sent by the passive tag to obtain the identification of the passive tag.

[0191] After obtaining the identifier of a passive tag, the smartwatch checks whether it has acquired the identifiers of one or more passive tags indicated in the preset identifier list. If, after a period of time, the smartwatch still has not acquired the identifiers of passive tags in the preset identifier list, it can issue a voice message or an audio-visual notification to prompt the user to check if the item has been lost.

[0192] Of course, after obtaining the identifier of a passive tag, the smartwatch can also send the identifier to the smartphone for processing. For example, if the smartphone still does not obtain the identifier of a passive tag from the preset identifier list within a certain period of time, the smartphone can issue a voice message or sound and light notification to prompt the user to check if the item has been lost.

[0193] The examples above illustrate how to interact with passive tags using different devices, such as a smartphone and a modem, or a smartphone and a smartwatch. In some embodiments, interaction with passive tags can also be achieved through different communication modules on the same device.

[0194] For example, Figure 12 is a schematic diagram of the architecture of another passive communication system provided in this application. As shown in Figure 12, the first communication device in the embodiment corresponding to Figure 9 is, for example, a Wi-Fi module built into a smartphone, and the second communication device is, for example, a Bluetooth module built into a smartphone. The passive tag has a built-in energy storage capacitor.

[0195] In this process, the Wi-Fi module in the smartphone first sends an excitation signal to enable the passive tag to charge the energy storage capacitor. Then, after interrupting the transmission of the excitation signal, the Wi-Fi module in the smartphone sends a single-tone carrier signal, which the passive tag reflects to send a reflected signal. During the period when the passive tag is sending the reflected signal, the Bluetooth module in the smartphone receives the reflected signal, parses it to obtain the passive tag's information, and then sends the obtained passive tag information back to the smartphone.

[0196] Please refer to Figure 13, which is a schematic diagram of a communication process between a smartphone and a passive tag provided in this application. As shown in Figure 13, the communication process between the smartphone and the passive tag includes the following steps 1301-1307.

[0197] Step 1301: The Wi-Fi module in the smartphone sends a locator request message to the Bluetooth module.

[0198] The Wi-Fi module and Bluetooth module in a smartphone can be connected via the smartphone's internal communication bus. Therefore, the Wi-Fi module can send a locator request message (the second message mentioned above) to the Bluetooth module via the communication bus. This locator request message requests the Bluetooth module to cooperate with the Wi-Fi module to begin searching for the item.

[0199] Step 1302: The Bluetooth module in the smartphone sends a location tracking response message to the Wi-Fi module.

[0200] After receiving a lost item request message, the Bluetooth module in the smartphone sends a lost item response message to the Wi-Fi module. This lost item negotiation message can indicate that the Bluetooth module is ready to execute the lost item process.

[0201] Step 1303: The Wi-Fi module in the smartphone sends an excitation signal to the passive tag and the Bluetooth module.

[0202] The excitation signal sent by the smartphone includes preset information. Furthermore, the smartphone's Wi-Fi module sends the excitation signal wirelessly to the passive tag and also sends it to the Bluetooth module via a communication bus. In other words, the Wi-Fi module sends the excitation signal wirelessly to the passive tag and sends it to the Bluetooth module via a wired connection.

[0203] Step 1304: The Bluetooth module in the smartphone receives and parses the excitation signal, and the passive tag receives the excitation signal and charges.

[0204] During the process of the Wi-Fi module in the smartphone sending the excitation signal, the Bluetooth module in the smartphone continuously receives and parses the excitation signal to obtain the preset information carried in the excitation signal. The passive tag then receives the excitation signal and charges the energy storage capacitor based on the received excitation signal.

[0205] Step 1305: After interrupting the transmission of the excitation signal, the Wi-Fi module in the smartphone transmits a single-tone carrier signal.

[0206] Step 1306: The passive tag sends a reflected signal by reflecting a single-tone carrier signal.

[0207] After the passive tag is fully charged and an interruption of the excitation signal is detected, the passive tag can start and enter the working state, thereby receiving and reflecting single-tone carrier signals, and then sending reflected signals. The reflected signals sent by the passive tag may include the tag's identifier.

[0208] Step 1307: The Bluetooth module in the smartphone receives and parses the reflected signal to obtain information about the passive tag.

[0209] After the Bluetooth module in the smartphone parses the preset information in the excitation signal and detects the interruption of the excitation signal, the Bluetooth module in the smartphone can enter the working state of receiving reflected signals, thereby receiving and parsing the reflected signals sent by the passive tag to obtain the identification of the passive tag.

[0210] After the Bluetooth module in a smartphone obtains the identifier of the passive tag, it can submit the identifier of the passive tag to the application in the smartphone, so that the application can perform corresponding processing steps based on the identifier of the passive tag.

[0211] This application also provides a passive tag, including a transceiver module and an energy storage unit, which cooperate to perform the steps performed by the passive tag in the embodiments described in Figures 2-13.

[0212] This application also provides a first communication device for performing the steps performed by the first communication device in the embodiments described in Figures 2-13.

[0213] This application also provides a second communication device for performing the steps performed by the second communication device in the embodiments described in Figures 2-13.

[0214] This application also provides a passive communication system, including a passive tag, a first communication device, and a second communication device as shown in the embodiments illustrated in Figures 2-13.

[0215] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0216] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0217] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A passive communication method, characterized in that, The method includes: The passive tag receives an excitation signal and charges itself based on the received excitation signal; After the passive tag is fully charged, the passive tag receives a single-tone carrier signal; The passive tag reflects the single-tone carrier signal to send a reflected signal, which is used to indicate information about the passive tag.

2. The method according to claim 1, characterized in that, After the passive tag is fully charged, the passive tag receives a single-tone carrier signal, including: After the passive tag is fully charged and the excitation signal is detected to be interrupted, the passive tag begins to receive a single-tone carrier signal.

3. The method according to claim 1 or 2, characterized in that, After the passive tag is fully charged, the passive tag receives a single-tone carrier signal, including: After the passive tag is fully charged, the passive tag parses the excitation signal to obtain the first information indicated in the excitation signal; If the first information is the same as the information of the passive tag, the passive tag triggers the reception of the single-tone carrier signal.

4. The method according to any one of claims 1-3, characterized in that, The passive tag reflects the single-tone carrier signal, including: After the passive tag begins receiving a single-tone carrier signal, the passive tag delays for a target duration before reflecting the single-tone carrier signal.

5. The method according to claim 4, characterized in that, The target duration is n times the preset duration, where n is an integer selected by the passive tag within a preset integer range, and the preset integer range includes multiple different integers.

6. The method according to any one of claims 1-5, characterized in that, The single-tone carrier signal and the reflected signal are located in different channels.

7. The method according to claim 6, characterized in that, The channel in which the reflected signal is located is a channel selected by the passive tag within a preset channel range, which includes multiple different channels.

8. The method according to any one of claims 1-7, characterized in that, The passive tag is considered fully charged when the voltage of the energy storage capacitor in the passive tag exceeds a threshold value.

9. A passive communication method, characterized in that, include: The first communication device receives an excitation signal sent by the second communication device, the excitation signal being used to charge the passive tag; After the excitation signal is interrupted, the first communication device sends a single-tone carrier signal, which is used to be reflected by the passive tag to obtain a reflected signal.

10. The method according to claim 9, characterized in that, After the excitation signal is interrupted, the first communication device sends a single-tone carrier signal, including: After the first communication device detects that the excitation signal carries preset information and the excitation signal is interrupted, the first communication device sends a single-tone carrier signal.

11. The method according to claim 10, characterized in that, The method further includes: The first communication device sends a first message to the second communication device. The first message includes the preset information and is used to instruct the second communication device to send an excitation signal carrying the preset information.

12. The method according to claim 10 or 11, characterized in that, The preset information includes the information of the passive tag.

13. The method according to any one of claims 9-12, characterized in that, The first communication device and the second communication device are located on different devices.

14. The method according to any one of claims 9-12, characterized in that, Both the first communication device and the second communication device are wireless communication modules, and the first communication device and the second communication device are integrated on the same device.

15. A passive communication method, characterized in that, The method includes: The second communication device sends an excitation signal, which is used to charge the passive tag; After ceasing to send the excitation signal, the second communication device receives a reflected signal sent by the passive tag. The reflected signal is used to indicate information about the passive tag, and the reflected signal is emitted by the passive tag by reflecting a single-tone carrier signal.

16. The method according to claim 15, characterized in that, The excitation signal carries preset information.

17. The method according to claim 16, characterized in that, The method further includes: The second communication device receives a first message sent by the first communication device. The first message includes the preset information and is used to instruct the second communication device to send an excitation signal carrying the preset information.

18. The method according to claim 15 or 16, characterized in that, The preset information includes the information of the passive tag.

19. A passive communication method, characterized in that, The method includes: The first communication device sends an excitation signal, which is used to charge the passive tag; After interrupting the transmission of the excitation signal, the first communication device transmits a single-tone carrier signal, which is used to be reflected by the passive tag to obtain a reflected signal.

20. The method according to claim 19, characterized in that, The excitation signal includes preset information, and the method further includes: The first communication device sends a second message to the second communication device, the second message including the preset information, and the second message is used to instruct the second communication device to start receiving the reflected signal after receiving the excitation signal including the preset information.

21. The method according to claim 19 or 20, characterized in that, The method further includes: The first communication device receives information from the passive tag sent by the second communication device, wherein the information of the passive tag is obtained by the second communication device by receiving the reflected signal; In response to whether the passive tag is included or not in the preset information list, the first communication device sends a prompt message, which indicates whether the target item has been found or not, and the preset information list indicates information about multiple passive tags.

22. A passive communication method, characterized in that, The method includes: The second communication device receives an excitation signal, which is used to charge the passive tag; After the excitation signal is interrupted, the second communication device receives a reflected signal sent by the passive tag. The reflected signal is used to indicate information about the passive tag, and the reflected signal is emitted by the passive tag by reflecting a single-tone carrier signal.

23. The method according to claim 22, characterized in that, The excitation signal includes preset information, and the method further includes: The second communication device receives a second message sent by the first communication device. The second message includes the preset information and is used to instruct the second communication device to start receiving the reflected signal after receiving an excitation signal including the preset information.

24. The method according to claim 22 or 23, characterized in that, The method further includes: The second communication device analyzes the reflected signal to obtain information about the passive tag; In response to whether the passive tag is included or not in the preset information list, the second communication device sends a prompt message, which indicates whether the target item has been found or not, and the preset information list indicates information on multiple passive tags.

25. A passive tag, characterized in that, The device includes a transceiver module and an energy storage unit, wherein the transceiver module and the energy storage unit cooperate to enable the passive tag to perform the method described in any one of claims 1-8.

26. A first communication device, characterized in that, The first communication device is used to perform the method described in any one of claims 9-14 or 19-21.

27. A second communication device, characterized in that, The second communication device is used to perform the method described in any one of claims 15-18 or 22-24.

28. A passive communication system, characterized in that, It includes the passive tag as described in claim 25, the first communication device as described in claim 26, and the second communication device as described in claim 27.

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