COMMUNICATION METHOD, DEVICE, AND SYSTEM

• US 20140139322A1
• Filed: 01/24/2014
• Published: 05/22/2014
• Est. Priority Date: 05/03/2011
• Status: Active Grant

• Current Assignee: Nationz Technologies Inc.
• Original Assignee: Nationz Technologies Inc.
• Inventors: WANG, HAIXIANG, DONG, RUI
• Granted Patent: US 9,400,903 B2
• Time in Patent Office: Days
• US Class Current: 340/10.5
• CPC Class Codes: G06F 21/83 input devices, e.g. keyboards, mice or controllers thereof
• CPC Class Codes: G06K 7/10267 the arrangement comprising a circuit inside of the interrogation device
• CPC Class Codes: G06K 7/10366 the interrogation device being adapted for miscellaneous applications
• CPC Class Codes: H04B 5/0031 for data transfer
• CPC Class Codes: H04B 5/0075 using inductive coupling transformers or inductances adapted for inductive coupling H01F38/14
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/72 for local intradevice communication

Abstract

The present invention relates to a communication method, device, and system. The communication method include using low-frequency alternating magnetic field signals to control a communication distance between a first radio frequency (RF) device and second RF device. The communication device receives and uses a first low-frequency alternating magnetic field signal transmitted from a second RF device to control the communication distance to the second RF device. The communication system includes a first RF device and a second RF device. The first RF device generates and transmits a first low-frequency alternating magnetic field signal and receives a second low-frequency alternating magnetic field signal, and the second RF device generates and transmits the second low-frequency alternating magnetic field signal and receives the first low-frequency alternating magnetic field signal. The first RF device and the second RF device control the communication distance using the first and second low-frequency alternating magnetic field signals.

Claims

1. A communication method, comprising:

controlling a communication distance between a first radio frequency (RF) device and a second RF device using a low-frequency magnetic field; and

exchanging information between the first RF device and the second RF device within a predetermined distance range using RF channels.

2. The communication method according to claim 1, wherein:

one of the first RF device and the second RF device receives a first low-frequency alternating magnetic field signal from the other of the first RF device and the second RF device to control communication distance between the first RF device and the second RF device.

3. The communication method according to claim 2, wherein receiving the first low-frequency alternating magnetic signal to control the communication distance further includes:

detecting the received first low-frequency alternating magnetic field signal;

converting the first low-frequency alternating magnetic field signal into a first electrical signal;

comparing the first electrical signal with a first preset threshold value; and

controlling the communication distance between the first RF device and second RF device based on a comparison result.

6. The communication method according to claim 2, wherein:

the first low-frequency alternating magnetic field signal is related to a frequency f0 and, when a frequency of first low-frequency alternating magnetic field signal is less than or equal to the frequency f0, the first RF device and the second RF device are within a valid distance range.

7. The communication method according to claim 6, wherein the first RF device is a card reader, the second RF device is a card, and the frequency f0 is determined by:

determining a distance control target (Din, Dv) based on the first low-frequency alternating magnetic field signal, wherein Din represents a distance in which, within a range of 0-Din, card transaction is ensured, and Dv represents a distance fluctuation range in which, within Din˜

(Din+Dv), card transaction is allowed and, beyond Din+Dv, card transaction is not allowed;

determining a detection voltage fluctuation range δ

_R of the card reader;

determining a detection voltage fluctuation range δ

_C of the card;

determining voltage-distance curves of the plurality typical terminals and obstacles at the frequency f of first low-frequency alternating magnetic field signal;

based on the distance control target (Din, Dv), determining a detection voltage fluctuation range δ

_A of the card reader, the range δ

_A being equal to a difference between a voltage corresponding to a distance point Din on a voltage-distance curve with an average field intensity attenuation curve slope and obtained from the voltage-distance curves of the plurality of typical terminals and obstacles and the voltage corresponding to a distance point (Din+Dv);

determining a detection voltage fluctuation range δ

_T of the of the card caused by a mobile terminal containing the card, the parameter δ

_T representing a fluctuation range of a detection voltage of the card caused by attenuation characteristics of the mobile terminal and δ

_T=δ

_A−

δ

_R−

δ

_C;

calculating a maximum field intensity difference δ

at various distances with distance control range of various typical terminals and obstacles;

if δ

is greater than δ

_T, decreasing the frequency f and continuing from the step of determining the voltage-distance curves;

if δ

is less than δ

_T, increasing the frequency f and continuing from the step of determining the voltage-distance curves; and

if δ

is equal to δ

_T, determining the current frequency f is the frequency f0.

8. The communication method according to claim 2, wherein the modulation mode, the coding mode, and the transmission magnetic flux density Bc of the first low-frequency alternating magnetic field signal is selected by:

selecting a coding mode without an average DC component;

selecting no modulation or a carrier modulation mode without amplitude change;

selecting the transmission magnetic flux density Bc by;

under a selected operating frequency that is less than f0, a selected modulation and a selected coding mode, selecting magnetic detection and the amplification gain that are easy to achieve by the card reader;

detecting an inherent noise voltage amplitude Vn of the detection voltage of the card reader when there is no low-frequency alternating magnetic field signal;

detecting the detection voltage Vr of the card reader when the card reader is sending the low-frequency alternating magnetic field signal using the selected modulation and coding mode; and

selecting the transmission magnetic flux density Bc such that such that Vr/Vn>

SNR, where SNR is signal-to-noise-ratio of the card reader.

14. The communication method according to claim 2, wherein:

the one of the first RF device and the second RF device sends a second low-frequency alternating magnetic field signal to the other of the first RF device and the second RF device with communication distance confirmation information.

15. The communication method according to claim 1, wherein:

one of the first RF device and the second RF device sends a first low-frequency alternating magnetic field signal to the other of the first RF device and the second RF device, and receives a second low-frequency alternating magnetic field signal from the other of the first RF device and the second RF device;

identification information carried in the second low-frequency alternating magnetic field signal is used to control communication distance between the first RF device and the second RF device.

17. The communication method according to claim 15, wherein:

one of the first RF device and the second RF device converts the second low-frequency alternating magnetic field signal into a second electrical signal and compares the second electrical signal with a second preset threshold; and

when the second electrical signal is greater than or equal to the second preset threshold and the identification information in the second low-frequency alternating magnetic field signal is the same as identification information of the one of the first RF device and the second RF device sending the first low-frequency alternating magnetic field signal, it is determined that the first RF device and the second RF device are within a valid distance range.

18. The communication method according to claim 15, wherein:

the other of the first RF device and the second RF device controls the communication distance between the first RF device and the second RF device based on received first low-frequency alternating magnetic field signal and, when it is considered that the first RF device and the second RF device are within a valid distance range, sends back the second low-frequency alternating magnetic field signal.

19. The communication method according to claim 18, wherein the other of the first RF device and the second RF device controlling the communication distance between the first RF device and the second RF device based on received first low-frequency alternating magnetic field signal further includes:

converting the first low-frequency alternating magnetic field signal into a first electrical signal;

comparing the first electrical signal with a first preset threshold value; and

controlling the communication distance between the first RF device and second RF device based on a comparison result.

21. The communication method according to claim 19, wherein:

the first electrical signal is a voltage signal, the first threshold value is a voltage threshold Vt, and the voltage threshold Vt is determined by;

under selected transmission parameters, measuring voltage-distance curves of a plurality of typical terminals and obstacles, the selected transmission parameters including a frequency of the low-frequency alternating magnetic field signal, a modulation mode, a coding mode, and a transmission magnetic flux density Br; and

obtaining a reference voltage-distance curve, the reference voltage-distance curve being a average value of curves of the typical terminals and obstacles; and

selecting a voltage value at a distance point at half of a maximum valid card transaction range on the reference voltage-distance curve as Vt for the card reader.

22. The communication method according to claim 18, wherein:

the first RF device is a card reader, the second RF device is a card, the first low-frequency alternating magnetic field signal is related to a frequency f0 and, when a frequency of first low-frequency alternating magnetic field signal is less than or equal to the frequency f0, mobile terminals equipped with the second RF device are within a valid distance range,

the frequency f0 is determined by;

determining a distance control target (Din, Dv) based on the first low-frequency alternating magnetic field signal, wherein Din represents a distance in which, within a range of 0-Din, card transaction is ensured for the mobile terminals equipped with the second RF device, and Dv represents a distance fluctuation range in which, within Din˜

(Din+Dv), card transaction is allowed and, beyond Din+Dv, card transaction is not allowed;

determining a detection voltage fluctuation range δ

_R of the second RF device caused by the first RF device;

determining a detection voltage fluctuation range δ

_C caused by the second RF device;

determining voltage-distance curves of the plurality typical terminals and obstacles at the frequency f of first low-frequency alternating magnetic field signal;

based on the distance control target (Din, Dv), determining a detection voltage fluctuation range δ

_A of the second RF device, the range δ

_A being equal to a difference between a voltage corresponding to a distance point Din on a voltage-distance curve with an average field intensity attenuation curve slope and obtained from the voltage-distance curves of the plurality of typical terminals and obstacles and the voltage corresponding to a distance point (Din+Dv);

determining a detection voltage fluctuation range δ

_T of the second RF device caused by a mobile terminal containing the second RF device, the parameter δ

_T representing a fluctuation range of a detection voltage of the card caused by attenuation characteristics of the mobile terminal and δ

_T=δ

_A−

δ

_R−

δ

_C;

calculating a maximum field intensity difference δ

at various distances with distance control range of various typical terminals and obstacles;

if δ

is greater than δ

_T, decreasing the frequency f and continuing from the step of determining the voltage-distance curves;

if δ

is less than δ

_T, increasing the frequency f and continuing from the step of determining the voltage-distance curves; and

if δ

is equal to δ

_T, determining the current frequency f is the frequency f0.

23. The communication method according to claim 18, wherein:

the first RF device is a card reader, the second RF device is a card, the second low-frequency alternating magnetic field signal is related to a frequency f0′ and

, when a frequency of second low-frequency alternating magnetic field signal is less than or equal to the frequency f0′

, mobile terminals equipped with the second RF device are within a valid distance range,

the frequency f0′

is determined by;

determining a distance control target (Din, Dv′

) based on the second low-frequency alternating magnetic field signal, wherein Din represents a distance in which, within a range of 0-Din, card transaction is ensured for the mobile terminals equipped with the second RF device, and Dv′

represents a distance fluctuation range in which, within Din˜

(Din+Dv′

), card transaction is allowed and, beyond Din+Dv′

, card transaction is not allowed;

determining a detection voltage fluctuation range δ

_R of the first RF device caused by the second RF device;

determining a detection voltage fluctuation range δ

_C caused by the first RF device;

determining voltage-distance curves of the plurality typical terminals and obstacles at the frequency f′

of second low-frequency alternating magnetic field signal;

based on the distance control target (Din, Dv′

), determining a detection voltage fluctuation range δ

_A′

of the first RF device, the range δ

_A′

being equal to a difference between a voltage corresponding to a distance point Din on a voltage-distance curve with an average field intensity attenuation curve slope and obtained from the voltage-distance curves of the plurality of typical terminals and obstacles and the voltage corresponding to a distance point (Din+Dv′

);

determining a detection voltage fluctuation range δ

_T′

caused by a mobile terminal containing the second RF device, the parameter δ

_T′

representing a fluctuation range of a detection voltage of the card caused by attenuation characteristics of the mobile terminal and δ

_T′

=δ

_A′

−

δ

_R′

−

δ

_C′

; and

calculating a maximum field intensity difference δ

′

at various distances with distance control range of various typical terminals and obstacles;

if δ

′

is greater than δ

_T′

, decreasing the frequency f and continuing from the step of determining the voltage-distance curves;

if δ

′

is less than δ

_T′

, increasing the frequency f and continuing from the step of determining the voltage-distance curves; and

if δ

′

is equal to δ

_T′

, determining the current frequency f′

is the frequency f0′

.

24. The communication method according to claim 18, wherein the modulation mode, the coding mode, and the transmission magnetic flux density Br of the first low-frequency alternating magnetic field signal is selected by:

selecting a coding mode without an average DC component;

selecting no modulation or a carrier modulation mode without amplitude change;

selecting the transmission magnetic flux density Br by;

under a selected operating frequency that is less than f0, a selected modulation and a selected coding mode, selecting a typical noise mobile terminal and magnetic detection and the amplification gain that are easy to achieve in the second RF device;

detecting an inherent noise voltage amplitude Vn of the detection voltage of the second RF device when there is no low-frequency alternating magnetic field signal;

detecting the detection voltage Vc of the second RF device when the first RF device is sending the low-frequency alternating magnetic field signal using the selected modulation and coding mode; and

selecting the transmission magnetic flux density Br such that such that Vc/Vn>

SNR, where SNR is signal-to-noise-ratio of the second RF device.

27. The communication method according to claim 24, wherein the modulation mode, the coding mode, and the transmission magnetic flux density Bc of the second low-frequency alternating magnetic field signal is selected by:

selecting a coding mode without an average DC component;

selecting no modulation or a carrier modulation mode without amplitude change;

selecting the transmission magnetic flux density Bc by;

under a selected operating frequency that is less than f0′

, the selected modulation and the selected coding mode, selecting a typical noise terminal and magnetic detection and the amplification gain that are easy to achieve by the first RF device;

detecting an inherent noise voltage amplitude Vn′

of the detection voltage of the first RF device when no low-frequency alternating magnetic field signal;

detecting the detection voltage Vr of the first RF device when the mobile terminal is sending the low-frequency alternating magnetic field signal using the selected modulation and coding mode; and

selecting the transmission magnetic flux density Bc such that such that Vr/Vn′

>

SNR′

, where SNR′

is signal-to-noise-ratio of the first RF device.

4. (canceled)

5. The communication method according to claim 4, wherein:

the first RF device is a card reader, the second RF device is a card, the first electrical signal is a voltage signal, and the first threshold value is a voltage threshold Vt,

wherein the voltage threshold Vt is determined by;

under selected transmission parameters, measuring voltage-distance curves of a plurality of typical terminals and obstacles, the selected transmission parameters including a frequency of the low-frequency alternating magnetic field signal, a modulation mode, a coding mode, and a transmission magnetic flux density Bc; and

obtaining a reference voltage-distance curve, the reference voltage-distance curve being a average value of curves of the typical terminals and obstacles; and

selecting a voltage value at a distance point at half of a maximum valid card transaction range on the reference voltage-distance curve as Vt for the card reader.

9-13. -13. (canceled)

16. (canceled)

20. (canceled)

25. (canceled)

26. (canceled)

28-33. -33. (canceled)

34. A radio frequency (RF) device, comprising:

a magnetic signal receiver module configured to receive a first low-frequency alternating magnetic field signal of another RF device;

a main control module configured to control a communication distance between the RF device and the another RF device; and

an RF transceiver module configured to exchange data with the another RF device within a predetermined distance range.

35. The RF device according to claim 34, wherein the main control module is further configured to:

convert the first low-frequency alternating magnetic field signal into a first electrical signal;

compare the first electrical signal with a first preset threshold value; and

control the communication distance between the first RF device and second RF device based on a comparison result.

36. The RF device according to claim 34, wherein:

the magnetic signal receiver module includes an amplifier circuit, a filter circuit, and a decoding circuit, sequentially connected;

the filter circuit is connected to a coupling coil in the RF device; and

the decoding circuit is connected to the main controller,

wherein;

the amplifier circuit is configured to amplify a first electrical signal converted from the first low-frequency alternating magnetic field signal received by the coupling coil;

the filter circuit is configured to filter the amplified first electrical signal and to suppress noise and interference outside a valid signal frequency band;

the decoding circuit is configured to decode the filtered signal based on the coding mode of the RF device sending the first low-frequency alternating magnetic field signal and to send the decoded signal to the main controller.

37. The RF device according to claim 36, wherein the magnetic signal receiver module further includes:

a demodulation circuit disposed between the filter circuit and the decoding circuit and configured to demodulate the filtered signal based on a modulation scheme used by the another RF device and to send the demodulated signal to the decoding circuit.

38. The RF device according to claim 34, wherein:

the magnetic signal receiver module includes an amplifier circuit and a filter circuit, sequentially connected;

the filter circuit is connected to a coupling coil in the RF device; and

the decoding circuit is connected to the main controller,

wherein;

the amplifier circuit is configured to amplify a first electrical signal converted from the first low-frequency alternating magnetic field signal received by the coupling coil;

the filter circuit is configured to filter the amplified first electrical signal and to suppress noise and interference outside a valid signal frequency band;

the main controller is further configured to decode the filtered signal based on the coding mode of the RF device sending the first low-frequency alternating magnetic field signal.

39. The RF device according to claim 38, the magnetic signal receiver module further includes:

a demodulation circuit disposed between the filter circuit and the main controller and configured to demodulate the filtered signal based on a modulation scheme used by the another RF device and to send the demodulated signal to the main controller.

40. The RF device according to claim 34, wherein:

the RF transceiver module includes an RF transceiver, an impedance matching network, and an RF antenna, sequentially connected, and the RF transceiver is connected to the main controller.

41. The RF device according to claim 34, further including:

a magnetic signal transmitting module configured to transmit the communication distance confirmation information to the another RF device.

42. The RF device according to claim 41, wherein:

the magnetic signal transmitting module includes an encoder circuit, a modulation circuit, a D/A converter circuit, and a drive circuit, sequentially connected, the encoder circuit is connected to the main controller, and the drive circuit is connected to the coupling coil in the RF device,

wherein;

the main controller is configured to generate information carried in the second low-frequency alternating magnetic field signal to be transmitted by the RF device, the second low-frequency alternating magnetic field signal information being a digital baseband signal;

the encoder circuit is configured to encode the digital baseband signal provided by the main controller;

the D/A converter circuit is configured to convert the encoded digital signal into a low-frequency analog signal; and

the drive circuit is configured to amplify the low-frequency analog signal and to drive the coupling coil to generate the second low-frequency alternating magnetic field.

43. The RF device according to claim 42, wherein the magnetic signal transmitting module further includes:

a modulation circuit disposed between the main controller and the D/A converter circuit,

wherein the modulation circuit is configured to modulate the encoded data and to send the modulated data to the D/A converter circuit.

44. The RF device according to claim 42, wherein the magnetic signal transmitting module further includes:

a modulation circuit disposed between the main controller and the D/A converter circuit,

wherein the modulation circuit is configured to modulate the encoded digital baseband signal and to send the modulated signal to the D/A converter circuit.

45. The RF device according to claim 41, wherein:

the magnetic signal transmitting module includes a D/A converter circuit and a drive circuit, sequentially connected, the D/A converter circuit is connected to the main controller, and the drive circuit is connected to the coupling coil in the RF device,

wherein;

the main controller is configured to generate low-frequency encoded data and to send the data to the D/A converter circuit;

the D/A converter circuit is configured to convert the low-frequency encoded data into a low-frequency analog signal; and

the drive circuit is configured to amplify the low-frequency analog signal and to drive the coupling coil to generate the second low-frequency alternating magnetic field.

46. The RF device according to claim 41, wherein:

the magnetic signal receiver module and the magnetic signal transmitting module perform two-way communication with the RF device transmitting the first low-frequency alternating magnetic field signal through a time-division duplex mode or a frequency-division duplex mode; and

an operating frequency of the magnetic signal receiver module and an operating frequency of the magnetic signal transmitting module both less than a predetermined maximum operating frequency.

47. A communication system comprising a first radio frequency (RF) device and second RF device, wherein the first RF device and the second RF device control a communication distance using low-frequency alternating magnetic field signals and exchange information between the first RF device and the second RF device using RF channels, wherein:

the first RF device further includes;

a first magnetic signal transceiver configured to generate and transmit a first low-frequency alternating magnetic field signal and to receive a second low-frequency alternating magnetic field signal;

a first RF communication unit configured to exchange information with the second RF device;

the second RF device further includes;

a second magnetic signal transceiver configured to generate and transmit the second low-frequency alternating magnetic field signal and to receive the first low-frequency alternating magnetic field signal;

a second RF communication unit configured to exchange information with the first RF communication unit.

48. The communication system according to claim 47, wherein:

the first magnetic signal transceiver further includes a first magnetic signal receiving unit and a first magnetic signal transmitting unit;

the first magnetic signal transmitting unit is configured to transmit the first low-frequency alternating magnetic field signal; and

the first magnetic signal receiving unit is configured to receive the second low-frequency alternating magnetic field signal;

the second magnetic signal transceiver further includes a second magnetic signal receiving unit and a second magnetic signal transmitting unit;

the second magnetic signal transmitting unit is configured to transmit the second low-frequency alternating magnetic field signal; and

the second magnetic signal receiving unit is configured to receive the first low-frequency alternating magnetic field signal.

49. The communication system according to claim 47, wherein:

the first magnetic signal transceiver includes a first modulation unit, and the first modulation unit is configured to add identification information of the first RF device into the first low-frequency alternating magnetic field signal; and

the second magnetic signal transceiver includes a second modulation unit, and the second modulation unit is configured to add identification information of the second RF device into the second low-frequency alternating magnetic field signal.

50. The communication system according to claim 49, wherein:

the first magnetic signal transceiver includes a first determination unit, and the first determination unit is configured to determine whether the first RF device enters into the preset valid card transaction range between the second RF device and the first RF device, based on the second low-frequency alternating magnetic field signal detected by the first RF device;

the second magnetic signal transceiver includes a second determination unit, and the second determination unit is configured to determine whether the second RF device enters into the preset valid card transaction range between the first RF device and the second RF device, based on the first low-frequency alternating magnetic field signal detected by the second RF device; and

when the second determination unit determines that the second RF device enters into the preset valid card transaction range between the first RF device and the second RF device, and when the first determination unit determines that the first RF device enters into the preset valid card transaction range between the second RF device and the first RF device, it is determined that the distance between the first RF device and the second RF device is within the predetermined effective communication distance range.

51. The communication system according to claim 50, wherein:

the first determination unit includes a first comparison sub-unit and a first determination sub-unit, the first comparison sub-unit is configured to compare the identification information of the first RF device demodulated from the second low-frequency alternating magnetic field signal with its own identification information; and

the first determination sub-unit is configured to, based on a comparison result, determine whether the first RF device enters into a predetermined valid distance range between the second RF device and the first RF device; and

the second determination unit includes a second comparison sub-unit and a second determination sub-unit, the second comparison sub-unit is configured to compare the electrical signal converted from the first low-frequency alternating magnetic field signal with the preset threshold value, and the second determination sub-unit is configured to, based on a comparison result, determine whether the second RF device enters into a predetermined valid distance range between the second RF device and the first RF device.

52. The communication system according to claim 51, wherein:

the first judgment unit includes a third comparison sub-unit and a third determination sub-unit, the third comparison sub-unit is configured to compare a second electrical signal converted from the second low-frequency alternating magnetic field signal with a second threshold value, and the third determination sub-unit is configured to, based on a comparison result, determine whether the second RF device enters into the predetermined valid distance range between the second RF device and the first RF device.