Automatic switching method for NFC emulated cards, mobile terminal, program product, and controller

Abstract

The present application provides an automatic switching method for NFC emulated cards, a mobile terminal, a program product, and a controller. The provided automatic switching method for NFC emulated cards comprises: when a card device enters a radio frequency field of a card reading device, extracting channel fingerprint characteristics of the card reading device; inputting the channel fingerprint characteristics into a classification model; determining an application scenario on the basis of output of the classification model; and selecting from the NFC emulated cards a target card corresponding to the determined application scenario.

Description

NFC analog card automatic switching method, mobile terminal, software product and controller

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202410677011.7, filed on May 28, 2024, entitled "Automatic Switching Method for NFC Analog Cards, Mobile Terminal, Program Product and Controller", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to near-field communication technology, and more specifically, to NFC analog card automatic switching technology. Background Technology

[0004] Near Field Communication (NFC) is an emerging technology. Devices using NFC technology (such as mobile terminals) can exchange data when they are close to each other.

[0005] Given the ease of use of NFC technology, a mobile terminal typically contains information on multiple analog cards that can communicate with trusted devices. In different scenarios, it's necessary to switch to the corresponding analog card to complete NFC communication. Currently, scene identification primarily relies on methods such as geographic location, screen status, motion sensing information, and historical behavioral data. These methods have relatively low accuracy in identifying target scenes, especially in complex scenarios or those with variable geographic locations.

[0006] Furthermore, these application-layer-based identifications occur closer to the application selection phase in the protocol. Executing the relevant judgment logic at this stage often requires changes to the existing communication process, such as requiring the user to wait for the judgment result, which has a certain impact on the user experience. Summary of the Invention

[0007] According to some embodiments of this application, an automatic switching method for NFC analog cards is provided to solve at least one of the above problems.

[0008] The provided NFC analog card automatic switching method includes extracting the channel fingerprint features of the card reader when the card device enters the radio frequency field of the card reader; inputting the channel fingerprint features into a classification model; determining the application scenario based on the output of the classification model; and selecting a target card from the analog cards that corresponds to the determined application scenario.

[0009] According to the NFC analog card automatic switching method of the present application embodiment, optionally, extracting the channel fingerprint features of the card reader includes: receiving a preamble signal sent by the card reader; calculating the radio frequency channel features of the card reader based on the preamble signal; extracting the amplitude and phase of the channel features from the radio frequency channel features; and using the extracted amplitude and phase as the channel fingerprint features of the card reader.

[0010] According to the NFC analog card automatic switching method of this application embodiment, optionally, the radio frequency channel characteristic information of the card reader is calculated based on the preamble signal, including calculating the radio frequency channel characteristics of the card reader using the following formula: Y=S*H

[0011] Wherein, Y represents the signal received by the card device from the card reader; S represents the preamble signal; and H represents the channel characteristics of the transmission channel between the card reader and the card device.

[0012] Extracting the amplitude and phase of the channel features from the radio frequency channel features includes determining the amplitude and phase of the channel features according to the following formula:

[0013] Wherein, h2 represents the channel characteristics of the card device; h0 represents the channel characteristics of the card reader; A0 represents the amplitude of the radio frequency channel characteristics; and θ0 represents the phase of the radio frequency channel characteristics.

[0014] According to the NFC analog card automatic switching method of the present application embodiment, optionally, the classification label of the classification model is set based on the production factors of the card reader.

[0015] According to the NFC simulation card automatic switching method of the embodiments of this application, optionally, a target card corresponding to a determined application scenario is selected from the NFC simulation cards, including obtaining the current application scenario of the NFC simulation card of the card device by the NFC management application of the card device; comparing the determined application scenario with the obtained current application scenario; if the comparison result is consistent, no switching is required; if the comparison result is inconsistent, switching is performed from the current simulation card used for the current application scenario to the target card; wherein, the current application scenario is the application scenario when the card device was swiped last time or is a set default application scenario.

[0016] According to other embodiments of this application, a mobile terminal is provided. The mobile terminal includes a memory for storing instructions; and a processor for executing the instructions, and, when executing the instructions, implementing any of the NFC analog card automatic switching methods described herein.

[0017] According to other embodiments of this application, a program product is provided, the program product including instructions that, when executed, implement any of the NFC analog card automatic switching methods described herein.

[0018] According to other embodiments of this application, a non-temporary storage medium is provided, the storage medium storing instructions that, when executed, implement any of the NFC analog card automatic switching methods described herein.

[0019] According to further embodiments of this application, an NFC controller is provided. The controller is configured to execute program instructions for implementing any of the NFC analog card automatic switching methods described herein.

[0020] In the examples above, mobile terminals include mobile phones, tablets, smart wearable devices, and laptops, among which smart wearable devices include smart bracelets, smartwatches, and smart glasses. Attached Figure Description

[0021] The embodiments of this application will be described in detail below with reference to the accompanying drawings, so that this application can be more fully understood, wherein:

[0022] Figure 1 is an exemplary illustration of an NFC analog card application environment;

[0023] Figure 2 is a flowchart of an NFC analog card automatic switching method according to some embodiments of this application;

[0024] Figure 3 is a flowchart of an NFC analog card automatic switching method according to some other embodiments of this application;

[0025] Figure 4 is a schematic diagram of a signal transmission path according to some embodiments of this application;

[0026] Figure 5 is a schematic diagram of the structure of a mobile terminal 5 according to some embodiments of this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the implementation methods of this application will be described more clearly and completely below in conjunction with the accompanying drawings. It should be noted that the described implementation methods are only some, not all, of the implementation methods of the technical solutions of this application. All other implementation methods obtained by those skilled in the art based on the implementation methods described in this application document without creative effort are covered by the protection scope of this application.

[0028] Figure 1 is an exemplary illustration of the application environment of an NFC emulator card. As shown in Figure 1, when a mobile terminal 20 equipped with an NFC emulator card is within the radio frequency field of a card reader 10, it communicates with the card reader 10 to select a card suitable for the current application scenario from among multiple NFC emulator cards stored in the mobile terminal 20 for card swiping.

[0029] Application scenarios include access control card swiping, public transportation card swiping, and life service card swiping (such as water, electricity, and gas cards). Different application scenarios correspond to different NFC analog cards.

[0030] Figure 2 is a flowchart of an NFC analog card automatic switching method according to some embodiments of this application. The method in the example shown in Figure 2 includes steps S200, S202, S204, and S206.

[0031] In step S200, when the card device enters the radio frequency field of the card reader, the channel fingerprint feature of the card reader is extracted.

[0032] Card devices, in examples but not limited to, include mobile terminals. Mobile terminals include, for example, mobile phones, tablets, smart wearable devices, laptops, etc., where smart wearable devices include, for example, smart bracelets, smartwatches, smart glasses, etc. Card devices can be various electronic devices that can set up NFC emulated cards and interact with NFC card readers. The card devices listed in the examples of this application are merely examples and are neither limited nor exhaustive.

[0033] During the manufacturing process of NFC card readers, due to factors such as material properties, processing technology, and assembly errors, each manufactured NFC card reader exhibits unique channel characteristics in its signal behavior at the physical layer. These channel characteristics are immediately apparent after the NFC card reader hardware is manufactured and do not change significantly over time; in other words, these channel characteristics are relatively constant. Embodiments of this application utilize these characteristics of radio frequency signals to identify different NFC devices, thereby identifying the usage scenario of the NFC device.

[0034] According to this example, when the card device enters the radio frequency field of the card reader, the card device receives a preamble signal emitted by the card reader. Based on the information carried by this preamble signal, the card device calculates the radio frequency channel characteristics of the card reader. For example, the card device extracts the amplitude and phase information of the radio frequency channel characteristics and uses both as the channel fingerprint characteristics of the card reader. It should be noted that in some other examples, one of the extracted amplitude and phase information of the radio frequency channel characteristics can be considered as the channel fingerprint characteristics of the card reader. In other examples, parameters other than the amplitude and phase information of the radio frequency channel characteristics can also be considered as channel fingerprint characteristics.

[0035] In step S202, the channel fingerprint features are input into the classification model.

[0036] The classification model is a pre-trained model set up in the card reader device. In this embodiment, the classification model is pre-trained. During training, data representing the manufacturer of the card reader device, the production batch of the card reader device, and the usage scenario of the card reader device can all be used as training data for the classification model. Specifically, this data serves as category labels to classify the channel fingerprint characteristics of the card reader device. This classification model can be based on algorithms such as Support Vector Machine (SVM).

[0037] In step S204, the application scenario is determined based on the output of the classification model.

[0038] After receiving the input channel fingerprint features, the classification model determines the category information of the channel fingerprint features and determines the application scenario of the card reader based on the category information.

[0039] In step S206, select the target card corresponding to the determined application scenario from among the multiple NFC analog cards set in the card device, that is, select the card suitable for the determined application scenario.

[0040] In this embodiment, the card device selects a target card corresponding to the determined application scenario from the NFC simulation card based on the determined application scenario information. Thus, the card device achieves automatic card switching and can complete the card swiping process with the switched card. For example, if the determined application scenario is access control, the card device will retrieve the identification card used for that access control from the NFC simulation card to complete the access control card swiping identification.

[0041] Compared to the manual selection of a card suitable for a specific application scenario when a user swipes an NFC simulated card, the method described in this application allows the card device to determine the application scenario of the card reader based on channel fingerprint characteristics. Accordingly, it selects the appropriate simulated card from multiple NFC simulated cards for that application scenario. In this process, the user does not need to manually select an applicable card from multiple simulated cards; instead, the card device automatically selects the NFC simulated card, improving the user experience. Furthermore, because the entire process eliminates manual selection, it saves time and increases card-swiping efficiency.

[0042] Figure 3 is a flowchart of an NFC analog card automatic switching method according to some other embodiments of this application. The method shown in Figure 3 is illustrated in the application environment shown in Figure 1, by way of example and not limitation.

[0043] In step S300, when the mobile terminal 20 enters the radio frequency field of the card reader 10, it receives the preamble signal sent by the card reader 10.

[0044] Based on the basic principles of communication, assuming the preamble signal sent by the transmitter is S and the signal received by the receiver is Y, the signal transmission process can be represented by formula (1): Y=S*H (1)

[0045] Here, H represents the channel characteristics of the transmission channel, and the preamble signal S is a pilot signal used for synchronization in existing communication protocols. The value of S is known in advance between the signal transmitter and the signal receiver based on the protocol. As an example, Y, S, and H are all vector data.

[0046] As shown in Figure 4, based on the signal propagation path, the transmission channel in this embodiment can be further decomposed into three parts: the radio frequency (RF) signal transmitter, the intermediate transmission, and the RF signal receiver. Therefore, H can be further refined into formula (2): H=h0*h1*h2 (2)

[0047] in, j is 0, 1, or 2, and h0, h1, and h2 are the channel characteristics of the three parts: the RF signal transmitter, the RF signal intermediate transmission, and the RF signal receiver, respectively. Among them, h0 is determined by the RF characteristics of the transmitting device as the signal transmitter, and h2 is determined by the RF characteristics of the receiving device as the signal receiver. Here, the RF characteristics of each device can be obtained through channel correction or equivalent channel. In this embodiment, the signal transmitting device can be a card reader 10, and the receiving device can be a mobile terminal 20 carrying an NFC analog card. Due to the short-range characteristics of NFC, the terminal 20 often needs to be placed close to the card reader 10 when swiping the card. Therefore, the signal is less affected and changes less during intermediate transmission. h1 can be approximated as 1. Therefore, H can be approximated as formula (3):

[0048] The mobile terminal 20, acting as the signal receiver, knows its channel characteristic h2. Based on this, the mobile terminal 20 can obtain the channel characteristic h0 of the card reader, which acts as the radio frequency signal transmitter, through formula (3). As mentioned above, h0 is determined by the hardware of the signal transmitter. When the device acting as the signal transmitter is manufactured, the channel characteristic is determined, so it is referred to as the channel fingerprint.

[0049] In step S302, the mobile terminal 20 calculates the radio frequency channel characteristics of the card reader 10 based on the preamble signal. Specifically, the channel characteristics of the transmission channel between the card reader and the card device can be calculated using formula (1), that is, the mobile terminal 20 calculates the channel characteristics H of the transmission channel between the card reader 10 and the mobile terminal 20 based on the preamble signal S sent by the card reader 10.

[0050] In step S304, the mobile terminal 20 extracts the amplitude and phase of the channel features from the radio frequency channel features. Specifically, the mobile terminal 20 calculates the channel features of the card device according to formula (3). It can be understood that for the mobile terminal 20, which is a card reader, h2 representing the channel features of the card reader is known. Therefore, given that the channel features H and h2 have been calculated according to formula (1) and are known, h0 can be calculated using formula (3). Then, the amplitude A0 representing the radio frequency channel features and the phase θ0 representing the radio frequency channel features are determined according to the following formula (4):

[0051] For example, when h0 is a complex number, the real part of h0 can be taken as the amplitude A0 and the imaginary part as the phase θ0.

[0052] In step S306, the mobile terminal 20 uses the determined amplitude A0 and phase θ0 as the channel fingerprint features of the card reader 10, thereby identifying the application scenario of the card reader 10. For example, the mobile terminal 20 identifies the card reader 10 as a subway gate based on the channel fingerprint features.

[0053] In step S308, the NFC management application of mobile terminal 20 obtains the current application scenario of the NFC simulation card in mobile terminal 20. The current application scenario refers to the application scenario corresponding to the card currently displayed in the NFC simulation card of mobile terminal 20. For example, the currently displayed card might be the card used during the previous card swipe by mobile terminal 20. For instance, if the card currently displayed by the mobile terminal is a subway card, then the current application scenario of mobile terminal 20 is a subway turnstile. Alternatively, the currently displayed card could be a default card, in which case the current application scenario would also be the default setting.

[0054] In step S310, the mobile terminal 20 compares the determined application scenario with the acquired current application scenario. If the comparison results are consistent, proceed to step S312; otherwise, proceed to step S314.

[0055] In step S312, no switching is required. That is, the current application scenario of the NFC simulation card of the mobile terminal 20 is consistent with the determined scenario, and the current card in the NFC simulation card of the mobile terminal 20 can be directly used to interact with the card reader to complete the card swiping operation.

[0056] In step S314, the current application scenario of the NFC simulation card of the mobile terminal 20 is inconsistent with the determined application scenario. Therefore, the mobile terminal 20 switches the current card in the NFC simulation card to the target card to adapt to the determined application scenario, thereby completing the card swiping operation.

[0057] Figure 5 is a schematic diagram of the structure of a mobile terminal 5 according to an example of this application. The mobile terminal 5 includes a memory 50 and a processor 52. The memory 50 stores instructions, and the processor 52 executes these instructions, implementing any of the NFC analog card automatic switching methods described above when executing the instructions. The mobile terminal 5 can, for example, be implemented as the mobile terminal 20 described above in conjunction with the accompanying drawings.

[0058] According to examples of this application, a controller is also provided, configured to execute any of the NFC analog card automatic switching methods described above. This controller may be, for example, a processor, in which executable program instructions are set to implement any of the NFC analog card automatic switching methods described above. This controller may be located, for example, in mobile terminal 20 or mobile terminal 5.

[0059] According to examples of this application, a non-temporary storage medium is also provided, wherein instructions are stored on the storage medium, which, when executed, implement any of the NFC analog card automatic switching methods described above.

[0060] According to examples in this application, a program product is also provided, the program product including instructions that, when executed, implement any of the NFC analog card automatic switching methods described above. This program product is, for example, an NFC management program.

[0061] Although specific embodiments of this application have been shown and described in detail to illustrate the principles of this application, it should be understood that this application may be implemented in other ways without departing from such principles, for example, the technical features of various embodiments / examples / exemplaries of this application may be combined with each other to form new implementation methods.

Claims

1. A method for automatic switching of NFC emulation cards, characterized in that, The method comprises: extracting a channel fingerprint feature of the card reading device when the card device enters a radio frequency field of the card reading device; inputting the channel fingerprint feature into a classification model; determining an application scenario according to an output of the classification model; selecting a target card corresponding to the determined application scenario from the NFC simulation cards.

2. The method of claim 1, wherein, The extracting of the channel fingerprint feature of the card reading device comprises: receiving a preamble signal sent by the card reading device; calculating a radio frequency channel feature of the card reading device according to the preamble signal; extracting an amplitude and a phase of the channel feature from the radio frequency channel feature; taking the extracted amplitude and phase as the channel fingerprint feature of the card reading device.

3. The method according to claim 2, characterized in that, The calculating of the radio frequency channel feature information of the card reading device according to the preamble signal comprises: calculating the radio frequency channel feature of the card reading device by the following formula: Y = S * H wherein Y represents a signal sent by the card reading device and received by the card device; S represents the preamble signal; and H represents a radio frequency channel feature of a transmission channel between the card reading device and the card device.

4. The method of claim 3, wherein, The extracting of the amplitude and the phase of the channel feature from the radio frequency channel feature comprises: The amplitude and phase of the channel characteristics are determined according to the following equations: wherein h2 represents a channel feature of the card device; h0 represents a channel feature of the card reading device; A0 represents an amplitude of the radio frequency channel feature; and θ0 represents a phase of the radio frequency channel feature.

5. The method of claim 1, wherein, The classification label of the classification model is set based on a production factor of the card reading device.

6. The method of claim 1, wherein, The selecting of the target card corresponding to the determined application scenario from the NFC simulation cards comprises: acquiring a current application scenario of an NFC simulation card in the card device by an NFC management application of the card device; comparing the determined application scenario with the acquired current application scenario; in a case where the comparison result is consistent, not switching; in a case where the comparison result is inconsistent, switching from a current simulation card used for the current application scenario to the target card; wherein the current application scenario is an application scenario when the card device is swiped the last time or is a default application scenario.

7. The method according to any one of claims 1 to 6, characterized in that, The card device is a mobile terminal.

8. A mobile terminal, characterized by The mobile terminal comprises: a memory for storing instructions; a processor for executing the instructions and implementing the NFC simulation card automatic switching method according to any one of claims 1 to 6 when the instructions are executed.

9. A program product, characterized by The program product comprises instructions which, when executed, implement the NFC simulation card automatic switching method according to any one of claims 1 to 6.

10. An NFC controller, characterized in that, The controller is configured to execute program instructions for implementing the NFC simulation card automatic switching method according to any one of claims 1 to 6.

11. A non-transitory storage medium characterized by The storage medium has instructions stored thereon, which, when executed, implement the NFC simulation card automatic switching method according to any one of claims 1 to 6.

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