Accurate end of PAUSE-A detection for near field communication

Abstract

A contactless communication device includes a near-field communication (NFC) module that generates an electromagnetic carrier signal and modulates the carrier signal according to data to be transmitted; and an antenna that is coupled to the NFC module via the modulated carrier signal and driven by the NFC module. The device includes an RF front-end coupled between the NFC module and the antenna, and a detection module coupled to the NFC module that detects the end of Pause A in the incoming RF signal by monitoring the amplitude of a digital output signal derived from the incoming RF signal. The detection module detects Pause A in the digital output signal by comparing the amplitude of the output digital signal with a first level. The detection module also detects the end of Pause A in the digital output signal by comparing the amplitude of the digital output signal with a second level.

Description

Technical Field

[0001] The present disclosure relates generally to contactless communications, and more particularly, to end of PauseA detection for near field communication (NFC). Background Art

[0002] NFC is a form of contactless communication between devices similar to smartphones or tablet computers. NFC devices can operate in three different modes based on the ISO / IEC 18092, NFC IP-1, and ISO / IEC 14443 contactless smart card standards. In read / write mode, an NFC device can read data in a standard NFC data format or write data to any supported tag type. In peer-to-peer (P2P) mode, two NFC devices can exchange data, such as virtual business cards or digital photos. You can also share Bluetooth or Wi-Fi link setting parameters to initiate a Bluetooth or Wi-Fi link in P2P mode. P2P mode is standardized under the ISO / IEC 18092 standard. In card emulation mode, an NFC device can act as a virtual version of any plastic card that complies with the core international standard for contactless smart cards, ISO / IEC 14443A / B (also known as ISO 14443 Type A and Type B). NFC devices may also support Sony's FeliCa contactless card technology, which is widely used in Japan for both contactless card payments and mobile payments.

[0003] According to the ISO / IEC 14443 standard, a proximity integrated circuit card (PICC) should detect the end of PauseA (PauseA is defined in ISO / IEC 14443 as a PCD "Proximity Coupling Device" modulated pulse, Type A) after the field exceeds 5% Hinitial and before the magnetic field exceeds 60% Hinitial (Hinitial is defined in ISO / IEC 14443 as the field strength of the unmodulated RF field). Figure 1 The definition of the end of PauseA for the bit rate fc / 128 (approximately 106 kbit / s) as defined in the ISO / IEC 14443 standard is shown.

[0004] During NFC communications, it's important to accurately detect the end of the last PauseA in a data frame received by the NFC device's receiver unit. The end of the last PauseA in a received data frame indicates the start of the frame delay time before the next transmission. However, the various shapes of PauseAs received in data frames can sometimes make it difficult to accurately detect the end of PauseA. Consequently, this can result in incorrect frame delay times being used between reception and transmission during communications. Summary of the Invention

[0005] An apparatus for contactless communication includes an NFC module adapted to generate an electromagnetic carrier signal and modulate the carrier signal according to data to be transmitted; an antenna coupled to the NFC module via the modulated carrier signal and driven by the NFC module; and an RF front end coupled between the NFC module and the antenna. The apparatus also includes a detection module coupled to the NFC module configured to detect the end of Pause A in an incoming RF signal by monitoring the amplitude of a digital signal derived from the incoming RF signal. The detection module detects Pause A in the digital signal by comparing the amplitude of the digital signal to a first level. The detection module also detects the end of Pause A in the digital signal by comparing the amplitude of the digital signal to a second level.

[0006] In one embodiment, if the amplitude of the digital signal is less than the first level, PauseA is detected in the digital signal.

[0007] In one embodiment, the first level is equal to Hinitial multiplied by a threshold.

[0008] In one embodiment, the threshold is first set to an initial threshold.

[0009] In one embodiment, if the amplitude of the digital signal is less than Hinitial multiplied by (threshold-5%) and the threshold is greater than 5%, the threshold is decreased by a first amount.

[0010] In one embodiment, the first amount is equal to 5%.

[0011] In one embodiment, the end of PauseA is detected in the digital signal if the amplitude of the digital signal is greater than the second level.

[0012] In one embodiment, the second level is equal to Hinitial multiplied by 85%.

[0013] In one embodiment, the RF front end includes one or more analog-to-digital converters (ADC, A / D, or A to D) for converting the incoming RF signal into an in-phase digital signal and a quadrature digital signal.

[0014] In one embodiment, the detection module further comprises a combining circuit, wherein the combining circuit is adapted to combine the in-phase digital signal and the quadrature digital signal to generate the digital signal.

[0015] A method for detecting the end of Pause A for near field communication (NFC) includes receiving an incoming RF signal; generating an in-phase signal and a quadrature signal from the incoming RF signal; combining the in-phase signal and the quadrature signal to generate a digital output signal; and detecting the end of Pause A for the incoming RF signal by monitoring the amplitude of the digital output signal. Detecting the end of Pause A for the incoming RF signal includes detecting Pause A in the digital output signal by comparing the amplitude of the digital output signal to a first level; and detecting the end of Pause A in the digital output signal by comparing the amplitude of the digital output signal to a second level.

[0016] In one embodiment, the method detects PauseA in the digital output signal if the amplitude of the digital output signal is less than the first level.

[0017] In one embodiment, the first level is equal to Hinitial multiplied by a threshold.

[0018] In one embodiment, if the amplitude of the digital output signal is less than Hinitial multiplied by (threshold-5%) and the threshold is greater than 5%, the method further comprises decreasing the threshold by a first amount.

[0019] In one embodiment, the method detects the end of PauseA in the digital output signal if the amplitude of the digital output signal is greater than the second level.

[0020] The above discussion is not intended to represent every example embodiment or every implementation within the scope of the current or future claim sets.

[0021] Various example embodiments can be more fully understood by considering the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The definition of the end of PauseA as defined in the ISO / IEC 14443 standard is shown.

[0023] Figure 2 It is an inductively coupled communication system.

[0024] Figure 3 is a schematic diagram illustrating the end of PauseA detection according to an embodiment of the present invention.

[0025] Figure 4 It is shown by Figure 3 Flowchart of a method for detecting the end of PauseA performed by the detection block.

[0026] While the present disclosure is susceptible to various modifications and alternative forms, details thereof have been shown by way of example in the drawings and will be described in detail. However, it should be understood that other embodiments besides the specific embodiments described are possible. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also encompassed. DETAILED DESCRIPTION

[0027] Figure 2 Depicting an inductively coupled communication system. Communication system 200 may include a first communication device 202 and a second communication device 204. First communication device 202 and second communication device 204 communicate with each other using inductively coupled communication. For example, inductively coupled communication may be NFC. Examples of communication devices include wireless communication devices, cellular phones, smartphones, tablet computers, voice recorders, digital cameras, still cameras, video cameras, gaming systems, laptop computers, and the like.

[0028] In inductive coupling communication, the first communication device 202 can generate an electromagnetic field, and the second communication device 204 can couple to the electromagnetic field. For example, in the case of NFC, the data flow direction can be characterized by the first communication device 202 (also known as a polling device, a proximity coupling device (PCD), a reader, or an initiator) providing the electromagnetic field. The second communication device 204 (also known as a listener, a listening device, a proximity integrated circuit card (PICC) tag, or a target) can communicate with the first communication device 202 by generating modulated content.

[0029] like Figure 2 As depicted in FIG, first communication device 202 may include transmitter 203 and receiver 201. The transmitter and receiver may be part of NFC module 206. First communication device 202 may also include RF or analog front-end module 205 and antenna 207. Second communication device 204 may include antenna 208, which is inductively coupled to antenna 207.

[0030] Figure 3 is a schematic diagram showing the end of PauseA detection according to an embodiment of the present invention. Figure 2 The communication device, for example, the first communication device 202 is implemented Figure 3 Schematic diagram of .

[0031] like Figure 3 As shown, the analog front end 304 receives an incoming RF signal 302. In one embodiment, the analog front end 304 includes one or more analog-to-digital converters (ADCs, A / Ds, or A to D) for converting the incoming signal into an in-phase digital signal 306 and a quadrature digital signal 308. The analog front end 304 outputs the in-phase digital signal and the quadrature digital signal.

[0032] like Figure 3 As depicted in FIG, the schematic 300 may also include an IQ combiner 310 that receives an in-phase digital signal 306 and a quadrature digital signal 308 from the analog front end 304 and combines the in-phase digital signal and the quadrature digital signal to produce a digital signal 312 at the output of the IQ combiner. The digital output signal 312 is provided to a detection block 316 for detecting the end of Pause A in the received digital output signal. In one embodiment, an adaptive threshold algorithm is implemented in the detection block 316 for detecting the end of Pause A in the digital output signal 312. This will be referred to as Figure 4 Explain in detail.

[0033] Figure 4 It is shown by Figure 3 Flowchart of a method for detecting the end of PauseA performed by the detection block.

[0034] refer to Figure 4 , the method 400 begins at step 402 in a first state, where PauseA is not detected in the received signal.

[0035] At step 405, initialization is performed to detect the end of PauseA in the received signal. During initialization, the value of the variable factor is set to an initial threshold, such as 70%. The initial threshold can be programmable by software and / or firmware. Method 400 also sets the value of high_level to the amplitude of the signal received in the first state. In one embodiment, high_level corresponds to Hinitial as defined in the ISO / IEC 14443 standard.

[0036] At step 406 , the amplitude adc_data_abs of the signal received at a particular moment is compared with the value of (high_level*factor).

[0037] If adc_data_abs is not less than the value of (high_level*factor), the method 400 returns to step 402. However, if adc_data_abs is less than the value of (high_level*factor), it indicates that Pause A is detected in the received signal. Therefore, at step 408, the signal fdt_sig (a signal indicating the start of the frame delay time) is set to "1". At step 410, the method 400 enters the second state, in which Pause A is detected in the received signal.

[0038] During the second state, at step 412 , the amplitude adc_data_abs of the received signal is continuously monitored for a value of (high_level*factor).

[0039] If adc_data_abs is less than the value of (high_level*factor), then at step 415, the signal fdt_sig is set to "1". At step 416, the amplitude of the received signal adc_data_abs is compared to the value of (high_level*(factor-5%)) and the value of factor is compared to 5%. If adc_data_abs is less than the value of (high_level*(factor-5%)) and the value of factor is greater than 5%, then at step 418, the value of factor is reduced by 5%. Otherwise, the method 400 returns to step 410. Here, if adc_data_abs is less than the value of (high_level*(factor-5%)) and the value of factor is greater than 5%, the value of factor is reduced by steps of 5%. In alternative embodiments, the value of factor is reduced by different amounts when the above given conditions are met.

[0040] On the other hand, if adc_data_abs is not less than the value of (high_level*factor) at step 412, adc_data_abs is compared with the value of (high_level*(factor+5%)) at step 420. If adc_data_abs is not greater than the value of (high_level*(factor+5%)), method 400 returns to step 410. Otherwise, at step 422, signal fdt_sig is set to "0".

[0041] At step 424, the amplitude of the received signal, adc_data_abs, is compared to the value of (high_level*85%). If adc_data_abs is not greater than the value of (high_level*85%), method 400 returns to step 410. However, if adc_data_abs is greater than the value of (high_level*85%), it indicates that the end of PauseA has been detected in the received signal. Therefore, at step 426, the value of high_level is set to "0" and the value of factor is set to the initial threshold value. Method 400 then returns to step 402.

[0042] The key operating principles of the above-mentioned method are summarized below.

[0043] PauseA is detected only when adc_data_abs<(high_level*factor), whereas the end of PauseA is detected when adc_data_abs>(high_level*85%).

[0044] The value of high_level cannot be modified during the second state (ie PauseA is detected in the received signal).

[0045] When adc_data_abs<(high_level*(factor-5%)) and factor is not less than 5%, the value of factor may only decrease in steps of 5% during the second state. This ensures that the value of factor can be set as low as possible to cooperate with each modulation index.

[0046] The signal fdt_sig is a signal for frame delay time. This signal is set to "1" when PauseA is detected and is reset to "0" when adc_data_abs>(high_level*(factor+5%)).

[0047] As provided herein, the above method allows for accurate detection of the end of PauseA, enabling accurate frame delay time to be used between reception and transmission during communication. An adaptive threshold algorithm is implemented for the above method, allowing for stable detection of the end of PauseA, regardless of the shape of the received signal.

[0048] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. It is intended that the appended claims cover all possible example embodiments.

[0049] In the claims, any reference signs placed in parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The indefinite article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In a device claim listing several means, several of these means may be embodied by the same item of hardware. The mere fact that certain measures are recited in different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A device for contactless communication, characterized in that include: a near field communication (NFC) module adapted to generate an electromagnetic carrier signal and modulate the carrier signal according to data to be transmitted, the NFC module comprising a transmitter and a receiver; an antenna, coupled to the NFC module and driven by the NFC module via a modulated carrier signal; an RF front end coupled between the NFC module and the antenna circuit; as well as a detection module coupled to the NFC module, the detection module adapted to detect an end of Pause A of the incoming RF signal by monitoring an amplitude of a digital signal derived from the incoming RF signal; wherein the detection module is adapted to detect the end of PauseA of the incoming RF signal by monitoring the amplitude of a digital signal derived from the incoming RF signal comprises: detecting the PauseA in the digital signal by comparing the amplitude of the digital signal to a first level; wherein the detection module is adapted to detect the end of PauseA of the incoming RF signal by monitoring the amplitude of a digital signal derived from the incoming RF signal comprises: detecting the end of PauseA in the digital signal by comparing the amplitude of the digital signal with a second level, Wherein, if the amplitude of the digital signal is less than the first level, then the PauseA is detected in the digital signal, Wherein, the first level is equal to Hinitial multiplied by the threshold, Wherein, if the amplitude of the digital signal is less than Hinitial multiplied by (the threshold value - 5%) and the threshold value is greater than 5%, the threshold value is reduced by a first amount.

2. The device according to claim 1, characterized in that The threshold is first set to an initial threshold.

3. The device according to claim 1, characterized in that The first amount is equal to 5%.

4. A device according to any one of the preceding claims, characterised in that If the amplitude of the digital signal is greater than the second level, the end of the PauseA is detected in the digital signal.

5. The device according to claim 3, characterized in that The second level is equal to Hinitial multiplied by 85%.

6. The device according to claim 1, It is characterized by: The RF front end includes one or more analog-to-digital converters (ADC, A / D, or A to D) for converting the incoming RF signal into an in-phase digital signal and a quadrature digital signal; and The detection module further comprises a combining circuit, wherein the combining circuit is adapted to combine the in-phase digital signal and the quadrature digital signal to generate the digital signal.

7. A method for detecting the end of PauseA of Near Field Communication (NFC), characterized in that: include: receiving an incoming RF signal; generating an in-phase signal and a quadrature signal from the incoming RF signal; combining the in-phase signal and the quadrature signal to generate a digital output signal; as well as detecting an end of PauseA of the incoming RF signal by monitoring the amplitude of the digital output signal, wherein detecting an end of PauseA of the incoming RF signal comprises, detecting the PauseA in the digital output signal by comparing the amplitude of the digital output signal to a first level; as well as detecting the end of the PauseA in the digital output signal by comparing the amplitude of the digital output signal to a second level, wherein if the amplitude of the digital output signal is less than the first level, then the PauseA is detected in the digital output signal, Wherein, the first level is equal to Hinitial multiplied by the threshold, Wherein, if the amplitude of the digital output signal is less than Hinitial multiplied by (the threshold value - 5%) and the threshold value is greater than 5%, the threshold value is reduced by a first amount.

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