Methods for recovering RFID data based upon probability using an RFID receiver

• US 9,613,236 B2
• Filed: 12/15/2014
• Issued: 04/04/2017
• Est. Priority Date: 10/28/2005
• Status: Expired due to Fees

• Current Assignee: Mojix Inc
• Original Assignee: Mojix Inc
• Inventors: Sadr, Ramin
• Primary Examiner(s): Khan, Omer S
• Application Number:
  US14/571,030
• Publication Number:
  US 20150169909A1
• Time in Patent Office: 841 Days
• Field of Search: 340 101
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/01 Details
• CPC Class Codes: G06K 7/10009 sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
• CPC Class Codes: H03M 13/098 using single parity bit
• CPC Class Codes: H03M 13/2957 Turbo codes and decoding
• CPC Class Codes: H03M 13/3905 Maximum a posteriori probability [MAP] decoding or approximations thereof based on trellis or lattice decoding, e.g. forward-backward algorithm, log-MAP decoding, max-log-MAP decoding
• CPC Class Codes: H03M 13/6331 Error control coding in combination with equalisation
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 25/0242 using matrix methods
• CPC Class Codes: H04L 25/03012 operating in the time domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04L 25/03114 non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals
• CPC Class Codes: H04L 25/03222 using the T-algorithm
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178
• CPC Class Codes: H04L 27/02 Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation H04L27/32 takes precedence
• CPC Class Codes: H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying H04L27/32 takes precedence

Abstract

RFID data signals from RFID tags may be recovered by determining the probabilities of transitions between data states between a series of a pairs of signal samples using a set of predetermined probabilities related to data, timing, baud rate and/or phase variables affecting the received signal and processing those determined probabilities to determine the sequence of such transitions that has the highest probability of occurrence. A second set of predetermined probabilities related to transitions in the opposite direction may be used to sequence in a reverse direction. The determination of the sequence representing the RFID tag data may be iterated in both directions until further iterations do not change the determined probabilities.

Claims

1. An adaptive noncoherent receiver for recovering RFID data transmitted over a communication channel comprising:

a converter configured to receive a phase modulated input signal and convert the received input signal into a vector representation by sampling the received input signal;

a channel equalizer comprising a filter bank, where the channel equalizer is configured to cancel interference associated with the communication channel by filtering the received input signal utilizing the filter bank and generate a first output signal;

a phase rotator configured to receive the first output signal and rotate the phase of the first output signal to generate a second output signal;

wherein the receiver further comprises a non-coherent estimation unit configured to receive the second output signal and generate a soft metric estimation;

wherein the non-coherent estimation unit is updated based upon feedback from a noncoherent soft-input-soft-out (SISO) decoder;

wherein the SISO decoder is updated utilizing the soft metric estimation;

wherein the SISO decoder is iteratively updated; and

a channel estimation unit configured to estimate a channel impulse response of the communication channel and update the filter bank.

2. The adaptive noncoherent receiver of claim 1, wherein the converter utilizes a demultiplexer for sampling the received input signal.

3. The adaptive noncoherent receiver of claim 1, wherein the filter bank includes a transfer function selected to match propagation environment of the communication channel.

4. The noncoherent receiver of claim 1, wherein the size of the vector representation is a predetermined length based upon the desired hardware complexity of the receiver.

5. The noncoherent receiver of claim 1, wherein the phase modulated input signal is a FMO encoded signal.

6. A method for recovering RFID data transmitted over a communication channel using an adaptive noncoherent receiver, the method comprising:

receiving a phase modulated input signal and converting the received input signal into a vector representation by sampling the received input signal using a converter;

canceling interference associated with the communication channel using a channel equalizer comprising a filter bank by filtering the received input signal utilizing the filter bank and generating a first output signal;

receiving the first output signal and rotating the phase of the first output signal to generate a second output signal using a phase rotator;

receiving the second output signal and generating a soft metric estimation using a non-coherent estimation unit;

updating the non-coherent estimation unit based upon feedback from a noncoherent soft-input-soft-out (SISO) decoder;

updating the SISO decoder utilizing the soft metric estimation;

wherein the SISO decoder is updated iteratively; and

estimating a channel impulse response of the communication channel and updating the filter bank using a channel estimation unit.

7. The method of claim 6, wherein the converter utilizes a demultiplexer for sampling the received input signal.

8. The method of claim 6, wherein the filter bank includes a transfer function selected to match propagation environment of the communication channel.

9. The method of claim 6, wherein the size of the vector representation is a predetermined length based upon the desired hardware complexity of the receiver.

10. The method of claim 6, wherein the phase modulated input signal is a FM0 encoded signal.