RFID systems using distributed exciter network
View Patent ↗RFID systems are disclosed that include at least one RFID receiver system and a distributed exciter architecture. Exciters can be connected via wired and/or wireless connections to the RFID receiver system, which can control activation of the exciters to detect the presence of RFID tags within interrogation spaces defined by the exciter topology. One embodiment includes an RFID receiver system configured to detect information from RFID tags within a receive coverage area, and a plurality of exciters defining a plurality of interrogation spaces within the receive coverage area of the receiver system. The receiver system is configured to transmit a control signal that identifies one of the exciters and includes information indicative of an RFID tag interrogation signal, the exciters are configured to receive the control signal, and the exciter identified in the control signal is configured to illuminate an interrogation space with the RFID tag interrogation signal.
1. An RFID system configured to manipulate RFID tags, comprising:
an RFID receiver system configured to read RFID tag information from activated RFID tags within a receive coverage area; and
a plurality of exciters defining a plurality of interrogation spaces within the receive coverage area of the RFID receiver system, where at least one of the plurality of exciters is able to activate an RFID tag within the plurality of interrogation spaces and the plurality of interrogation spaces are contained within the receive coverage area of the RFID receiver system;
wherein one of the plurality of exciters is a wired exciter with which the RFID receiver system communicates via a wired connection, where the wired exciter comprises:
a coupler configured to split a received RF signal;
an RF chain including a receive low noise amplifier; and
a transmit antenna;
wherein the RFID receiver system is configured to transmit a control signal to one of the plurality of exciters and includes an RFID tag interrogation signal;
wherein the wired exciter is configured to receive the control signal;
wherein the wired exciter is configured to couple the control signal into the RF chain to amplify the RFID tag interrogation signal received via the control signal and illuminate an interrogation space with the amplified RFID tag interrogation signal using the transmit antenna and thereby activate an RFID tag within the interrogation space;
wherein the wired exciter is configured to return exciter status information to the RFID receiver system by generating a waveform that emulates an illuminated RFID tag when the control signal includes a message to control the reporting of exciter status information; and
wherein the RFID receiver system is configured to read RFID tag information from an RFID tag activated by an RFID tag interrogation signal generated by one of the plurality of exciters.
2. The RFID system of claim 1 , wherein the RFID receiver system is configured to transmit control signals that activate a plurality of the exciters to transmit RFID tag interrogation signals concurrently using different frequencies.
3. The RFID system of claim 2 , wherein the control signals transmitted by the RFID receiver system cause the plurality of activated exciters to transmit in accordance with a frequency hopping protocol.
4. The RFID system of claim 2 , wherein the RFID receiver system is configured to allocate frequencies to exciters randomly.
5. The RFID system of claim 2 , wherein:
the RFID receiver system possesses information concerning the exciter distribution topology; and
the RFID receiver system uses the topology information when allocating frequencies to activated exciters.
6. The RFID system of claim 1 , wherein the control signal includes an n-bit address.
7. The RFID system of claim 1 , wherein the control signal includes all the necessary signal characteristics and parameters to generate the desired waveform output from the exciter.
8. The RFID system of claim 7 , wherein the control signal includes information that can be used by an exciter to perform transmit power calibration.
9. The RFID system of claim 1 , further comprising:
a second RFID receiver system configured to detect information from RFID tags within a second receive coverage area; and
a plurality of exciters defining a plurality of interrogation spaces within the receive coverage area of the second RFID receiver system;
wherein the second RFID receiver system is configured to transmit a control signal that identifies one of the plurality of exciters and includes information indicative of an RFID tag interrogation signal;
wherein the plurality of exciters within the coverage area of the second RFID receiver system are configured to receive the control signal from the second RFID receiver system; and
wherein the exciter identified in the control signal is configured to illuminate an interrogation space within the coverage area of the second RFID receiver system with the RFID tag interrogation signal.
10. The RFID system of claim 1 , wherein:
the RFID receiver system is configured to detect RFID tag information when an exciter illuminates an interrogation space with an RFID tag interrogation signal; and
the RFID receiver system is configured to determine whether the detected RFID tag information is from an RFID tag located within the interrogation space illuminated by the exciter.
11. The RFID system of claim 10 , further comprising:
a sensor located within the illuminated interrogation space configured to detect changes within the interrogation space;
wherein the sensor is configured to communicate sensor output to the RFID receiver system; and
wherein the RFID receiver system is configured to determine whether the detected RFID tag information is from an RFID tag located within the interrogation space illuminated by the exciter using information including the sensor output.
12. The RFID system of claim 10 , wherein:
the RFID receiver system is configured to detect RFID tag information when other exciters illuminate other interrogation spaces with RFID tag interrogation signals; and
the RFID receiver system is configured to determine whether the detected RFID tag information is from an RFID tag located within the interrogation space illuminated by the exciter using information including the RFID tag information detected when other exciters illuminated other interrogation spaces.
13. The RFID system of claim 10 , wherein:
the RFID tag information is an RF signal;
the RFID receiver system is configured to collect information concerning features of the RFID tag information RF signal; and
the RFID receiver system is configured to determine whether the detected RFID tag information is from an RFID tag located within the interrogation space illuminated by the exciter using information including the features of the RFID tag information RF signal.
14. The RFID system of claim 13 , wherein the collected features of the RFID tag information RF signal include signal strength, signal-to-noise ratio, and direction of arrival.
15. The RFID system of claim 10 , wherein:
the RFID receiver system repeatedly causes a plurality of exciters to sequentially illuminate a plurality of interrogation spaces and records the detection of RFID tag information; and
the RFID receiver system is configured to determine whether detected information is from an RFID tag located within an interrogation space illuminated by one of the plurality of exciters using information including the read rate at which the RFID tag information is detected when the interrogation space is illuminated.
16. The RFID system of claim 15 , wherein:
the RFID receiver system possesses information concerning the exciter topography;
the RFID receiver system is configured to estimate expected detection rates for RFID tags in different interrogation spaces; and
the RFID receiver system is configured to determine whether detected information is from an RFID tag located within an interrogation space illuminated by one of the plurality of exciters using information including the read rate at which the RFID tag information is detected when the interrogation space is illuminated and the expected detection rates for RFID tags in different interrogation spaces.
17. The RFID system of claim 16 , wherein the RFID receiver system is configured to determine movement of an RFID tag from one interrogation space to another interrogation space using information including the rate at which the information is detected when interrogation spaces are illuminated and the expected detection rates for RFID tags in different interrogation spaces.
18. An RFID system configured to manipulate RFID tags, comprising:
an RFID receiver system configured to read RFID tag information from activated RFID tags within a receive coverage area; and
a plurality of exciters defining a plurality of interrogation spaces within the receive coverage area of the RFID receiver system, where at least one of the plurality of exciters is able to activate an RFID tag within the plurality of interrogation spaces and the plurality of interrogation spaces are contained within the receive coverage area of the RFID receiver system;
wherein one of the plurality of exciters is a wireless exciter with which the RFID receiver system communicates via a wireless connection, where the wireless exciter comprises:
a receive antenna;
an RF synthesizer; and
a transmit antenna;
wherein the RFID receiver system is configured to transmit control signals to the plurality of exciters, where the control signals identify and activate a plurality of exciters to transmit RFID tag interrogation signals concurrently using different frequencies;
wherein the RFID receiver system is configured to transmit an RFID tag interrogation signal on a first frequency;
wherein the wireless exciter is configured to receive a control signal using the receive antenna;
when the wireless exciter is identified in the control signal, the wireless exciter is configured to:
down convert an RFID tag interrogation signal received via the receive antenna;
upconvert the baseband signal to a second transmit frequency generated by the RF synthesizer; and
illuminate an interrogation space with the upconverted RFID tag interrogation signal using the transmit antenna to activate an RFID tag within the interrogation space;
wherein the wireless exciter is configured to return exciter status information to the RFID receiver system by generating a waveform that emulates an illuminated RFID tag when the control signal includes a message to control the reporting of exciter status information; and
wherein the RFID receiver system is configured to read RFID tag information from an RFID tag activated by an RFID tag interrogation signal generated by one of the plurality of exciters.
19. The RFID system of claim 18 , wherein the control signals transmitted by the RFID receiver system cause the plurality of activated exciters to transmit in accordance with a frequency hopping protocol.
20. The RFID system of claim 18 , wherein:
the RFID receiver system is configured to detect RFID tag information when an exciter illuminates an interrogation space with an RFID tag interrogation signal; and
the RFID receiver system is configured to determine whether the detected RFID tag information is from an RFID tag located within the interrogation space illuminated by the exciter.
21. The RFID system of claim 20 , further comprising:
a sensor located within the illuminated interrogation space configured to detect changes within the interrogation space;
wherein the sensor is configured to communicate sensor output to the RFID receiver system; and
wherein the RFID receiver system is configured to determine whether the detected RFID tag information is from an RFID tag located within the interrogation space illuminated by the exciter using information including the sensor output.
22. The RFID system of claim 20 , wherein:
the RFID receiver system is configured to detect RFID tag information when other exciters illuminate other interrogation spaces with RFID tag interrogation signals; and
the RFID receiver system is configured to determine whether the detected RFID tag information is from an RFID tag located within the interrogation space illuminated by the exciter using information including the RFID tag information detected when other exciters illuminated other interrogation spaces.
23. The RFID system of claim 20 , wherein:
the RFID tag information is an RF signal;
the RFID receiver system is configured to collect information concerning features of the RFID tag information RF signal; and
the RFID receiver system is configured to determine whether the detected RFID tag information is from an RFID tag located within the interrogation space illuminated by the exciter using information including the features of the RFID tag information RF signal.
24. The RFID system of claim 23 , wherein the collected features of the RFID tag information RF signal include signal strength, signal-to-noise ratio, and direction of arrival.
25. The RFID system of claim 20 , wherein:
the RFID receiver system repeatedly causes a plurality of exciters to sequentially illuminate a plurality of interrogation spaces and records the detection of RFID tag information; and
the RFID receiver system is configured to determine whether detected information is from an RFID tag located within an interrogation space illuminated by one of the plurality of exciters using information including the read rate at which the RFID tag information is detected when the interrogation space is illuminated.
26. The RFID system of claim 25 , wherein:
the RFID receiver system possesses information concerning the exciter topography;
the RFID receiver system is configured to estimate expected detection rates for RFID tags in different interrogation spaces; and
the RFID receiver system is configured to determine whether detected information is from an RFID tag located within an interrogation space illuminated by one of the plurality of exciters using information including the read rate at which the RFID tag information is detected when the interrogation space is illuminated and the expected detection rates for RFID tags in different interrogation spaces.
27. The RFID system of claim 26 , wherein the RFID receiver system is configured to determine movement of an RFID tag from one interrogation space to another interrogation space using information including the read rate at which the information is detected when interrogation spaces are illuminated and the expected detection rates for RFID tags in different interrogation spaces.
28. The RFID system of claim 18 , where the frequency of the second RF frequency is the same as the frequency of the first RF frequency.