Device, system and method for compensating signal delays in an RFID communication system
View Patent ↗An RFID communication system comprises an NFC device ( 11 ) and a smart card ( 2 ) with contactless card functionality, wherein the NFC device ( 11 ) and the smart card ( 2 ) are couplable to each other via a protocol converter ( 7 ), wherein the NFC device ( 11 ) is coupled to an antenna ( 3 ) to receive electromagnetic signals (ES) from an RFID reader/writer and to transmit response signals (RS) to the RFID reader/writer by modulating received electromagnetic signals (ES). The electromagnetic signals (ES) contain first and second characteristic components (FE, RE) which define the begin and the end of a predefined signal pattern (PA), wherein the second characteristic component triggers a predefined response delay time (FDT) at the expiration of which the RFID communication system has to respond to the RFID reader/writer. A device ( 12 ) for compensating signal delays is provided that comprises signal pattern shortening means ( 13 ).
1. A device for compensating signal delays in an RFID communication system, the device comprising:
an NFC device coupled to an antenna to receive electromagnetic signals from an RFID reader/writer and to transmit response signals to the RFID reader/writer by modulating received electromagnetic signals, wherein the electromagnetic signals contain first and second characteristic components which define the begin and the end of a predefined signal pattern, wherein the NFC device is configured and arranged to transmit the response signals to the RFID reader/writer after a predefined response delay time, in response to the second characteristic component;
a signal pattern shortening circuit configured and arranged to compensate for signal delays by shortening the signal pattern of the received signal; and
a smart card with contactless card functionality, wherein the NFC device and the smart card are coupled to each other via a protocol converter, the signal pattern shortening circuit being configured and arranged to provide the received signal with the shortened signal pattern to the smart card via the protocol converter.
2. The device according to claim 1 , wherein the signal pattern shortening circuit includes a signal generator configured and arranged to generate and output the received signal with the shortened signal pattern, and to stop outputting the signal in response to the first characteristic component of the signal pattern being detected, and wherein the signal generator is configured and arranged to start starts to output signals again after a predefined shortened signal pattern time.
3. The device according to claim 2 , wherein the electromagnetic signals transmitted by the RFID reader/writer include a carrier signal that is modulated by a data signal wherein the signal generator is configured and arranged to generate and output the received signal with the shortened signal pattern by generating an outputting a signal having a frequency equal to the frequency of the carrier signal.
4. The device according to claim 1 , wherein the first and second characteristic components of the signal pattern are falling or rising signal edges.
5. The device according to- claim 1 , wherein the predefined signal pattern is a signal pause pattern.
6. The device according to claim 1 , further comprising a response delay circuit configured and arranged to delay a response from the smart card by an additional delay time.
7. The device according to claim 6 , wherein the response delay circuit is configured and arranged to adjust the additional delay time.
8. The device according to claim 7 , wherein the response delay circuit is configured and arranged to adjust the additional delay time to delay the response signal to the RFID reader/writer until the response delay time counted from the occurrence of the second characteristic component has expired.
9. An RFID communication system, comprising:
an NFC device coupled to an antenna to receive electromagnetic signals from an RFID reader/writer and to transmit response signals to the RFID reader/writer by modulating received electromagnetic signals, wherein the electromagnetic signals contain first and second characteristic components which define the begin and the end of a predefined signal pattern, wherein the NFC device is configured and arranged to transmit the response signals to the RFID reader/writer after a predefined response delay time, in response to the second characteristic component;
a device for compensating signal delays that includes a signal pattern shortening circuit configured and arranged to generate a signal having a shortened signal pattern, based on the received electromagnetic signals; and
a smart card with contactless card functionality, wherein the NFC device and the smart card are coupled to each other via a protocol converter.
10. The RFID communication system according to claim 9 , wherein the system complies with ISO 14443.
11. A method for compensating signal delays in an RFID communication system, the method comprising:
receiving electromagnetic signals from an RFID reader/writer by an NFC device coupled to an antenna;
compensating for signal delays by generating signals having a shortened signal pattern, from the received electromagnetic signals; and
transmitting response signals to the RFID reader/writer by the NFC device by modulating the received electromagnetic signals, wherein the electromagnetic signals contain first and second characteristic components which define the begin and the end of a predefined signal pattern, and by triggering a predefined response delay time based upon the second characteristic component at the expiration of which the RFID communication system transmits the response signals to the RFID reader/writer.
12. The method according to claim 11 , further comprising:
detecting the first characteristic component; and
wherein generating signals having a shortened signal pattern includes
stopping a square-wave signal generator from generating signals when the first characteristic component is detected so that the signal pattern is shortened, and
restarting the square-wave signal generator to output signals after a predetermined shortened signal pattern time after the detection of the first characteristic component.
13. The method according to claim 12 , wherein the electromagnetic signals received from the RFID reader/writer include a carrier signal that is modulated by a data signal wherein the frequency of the signals generated by the signal generator are equal to the frequency of the carrier signal.
14. The method according to claim 11 , wherein the first and second characteristic components of the signal pattern are falling or rising signal edges.
15. The method according to claim 11 , wherein the predefined signal pattern is a signal pause pattern.
16. The method according to claim 11 , further comprising
providing the generated signals having a shortened signal pattern to a smart card via a protocol converter,
providing a response from the smart card to the generated signals, to the NFC device, and
delaying the response from the smart card by an additional delay time.
17. The method according to claim 16 , wherein the additional delay time is adjusted in operation.
18. The method according to claim 17 , wherein the additional delay time is adjusted such that a response signal is delayed until the response delay time counted from the occurrence of the second characteristic component has expired.