Signature-based RFID localization

1. A Radio Frequency Identification (RFID) localization system,

comprising:

a set of passive RFID tags, each of the passive RFID tags in the set for reflecting transmitted signals;

an RFID reader for detecting the reflected signals by the set of passive RFID tags; and

a processor for localizing an object in an area based on the reflected signals by computing signatures using probabilistic macro-channels between the RFID reader and locations of the passive RFID tags, wherein the transmitted signals form inputs to the probabilistic macro-channels, and the computed signatures form outputs from the probabilistic macro-channels,

wherein the outputs from the probabilistic macro-channel at least comprise a received signal strength, an antenna port number, an excitation frequency, a phase shift between at least one of the transmitted signals and at least one of the reflected signals, and Doppler derived signal.

2. The RFID localization system of claim 1 , wherein the probabilistic macro-channels are modeled as log-likelihood ratio functions which provide respective likelihoods that the probabilistic macro-channels can generate respective output sequences given respective input sequences.

3. The RFID localization system of claim 1 , wherein the inputs to the probabilistic macro-channels further comprise an antenna variable indicative of one of a plurality of available antennas.

4. The RFID localization system of claim 1 , wherein the inputs to the probabilistic macro-channels further comprise a frequency variable indicative of one of a plurality of available frequencies.

5. The RFID localization system of claim 1 , wherein the inputs to the probabilistic macro-channels depend on discrete values of transmitted codewords in the transmitted signal and an input power of the transmitted signal.

6. The RFID localization system of claim 1 , wherein the outputs from the probabilistic macro-channels selectively comprise a first binary value representing the presence of a response and a second binary value representing an absence of the response.

7. A method for Radio Frequency Identification (RFID) localization, comprising:

reflecting, by a set of passive RFID tags, transmitted signals; and

detecting, by an RFID reader, the reflected signals by the passive RFID tags;

localizing, by a processor, an object in an area based on the reflected signals by computing signatures using probabilistic macro-channels between the RFID reader and locations of the passive RFID tags, wherein the transmitted signals form inputs to the probabilistic macro-channels, and the computed signatures form outputs from the probabilistic macro-channels,

wherein the outputs from the probabilistic macro-channel at least comprise a received signal strength an antenna port number, an excitation frequency, a phase shift between at least one of the transmitted signals and at least one of the reflected signals, and Doppler derived signal.

8. The method of claim 7 , wherein the probabilistic macro-channels are modeled as log-likelihood ratio functions which provide respective likelihoods that the probabilistic macro-channels can generate respective output sequences given. respective input sequences.

9. The method of claim 7 , wherein the inputs to the probabilistic macro-channels further comprise an antenna variable indicative of one of a plurality of available antennas.

10. The method of claim 7 , wherein the inputs to the probabilistic macro-channels further comprise a frequency variable indicative of one of a plurality of available frequencies.

11. The method of claim 7 , wherein the inputs to the probabilistic macro-channels depend on discrete values of transmitted codewords in the transmitted signal and an input power of the transmitted signal.

12. The method of claim 7 , wherein the outputs from the probabilistic macro-channels selectively comprise a first binary value representing the presence of a response and a second binary value representing an absence of the response.

13. A computer program product for Radio Frequency Identification (RFID) localization, the computer program product comprising a non-transitory computer readable storage medium having program instructions embodied therewith, the program instructions executable by a computer to cause the computer to perform a method comprising:

localizing, by a processor of the computer, an object an area, based on signals reflected from a set of passive RFID tags and the signals detected by an RFID reader coupled to the processor, by computing signatures using probabilistic macro-channels between the RFID reader and locations of the passive RFID tags, wherein the transmitted signals form inputs to the probabilistic macro-channels, and the computed signatures form outputs from the probabilistic macro-channels,

wherein the outputs from the probabilistic macro-channel at least comprise a received signal strength, an antenna port number, an excitation frequency, a phase shift between at least one of the transmitted signals and at least one of the reflected signals, and Doppler derived signal.

14. The computer program product of claim 13 , wherein the probabilistic macro-channels are modeled as log-likelihood ratio functions which provide respective likelihoods that the probabilistic macro-channels can generate respective output sequences given respective input sequences.

15. The computer program product claim 13 , wherein the inputs to the probabilistic macro-channels further comprise an antenna variable indicative of one of a plurality of available antennas.

16. The computer program product of claim 13 , wherein the inputs to the probabilistic macro-channels further comprise a frequency variable indicative of one of a plurality of available frequencies.

17. The computer program product of claim 13 , wherein the inputs to the probabilistic macro-channels depend on discrete values of transmitted codewords in the transmitted signal and an input power of the transmitted signal.