×

Message retrieving system with signal collision mitigation and a method thereof

  • US 9,680,512 B2
  • Filed: 07/11/2013
  • Issued: 06/13/2017
  • Est. Priority Date: 07/11/2013
  • Status: Active Grant
First Claim
Patent Images

1. A method for isolating response signals from colliding response signals of multiple radio frequency identification (RFID) tags by a RFID reader, the method comprising:

  • transmitting, from the RFID reader to the multiple RFID tags, a first waveform from a first antenna of the RFID reader;

    transmitting, from the RFID reader to the multiple RFID tags simultaneously with transmitting the first waveform, a second waveform from a second antenna of the RFID reader, wherein the first waveform is orthogonal to the second waveform, and wherein the first antenna is orthogonal to the second antenna;

    receiving, at the first antenna of the RFID reader while the RFID reader is transmitting the first waveform, response signals that collide at a time slot from two or more RFID tags of the multiple RFID tags, the multiple signals received at the first antenna including a signal from a first RFID tag responsive to the first waveform and a signal from a second RFID tag responsive to the first waveform, wherein the first and second RFID tags each include an antenna, and wherein the first RFID tag antenna is randomly disposed in a different orientation than the second RFID tag antenna, and wherein a polarization angle of the antenna of the first RFID tag aligns with a polarization angle of the first antenna and the first antenna receives a stronger signal responsive to the first waveform from the first RFID tag than from the second RFID tag;

    receiving, at the second antenna of the RFID reader while the RFID reader is transmitting the second waveform and simultaneously with receiving the response signals at the first antenna, response signals that collide at the time slot from the two or more RFID tags of the multiple RFID tags, the multiple signals received at the second antenna including a signal from the first RFID tag responsive to the second waveform and a signal from the second RFID tag responsive to the second waveform, wherein a polarization angle of the antenna of the second RFID tag aligns with a polarization angle of the second antenna and the second antenna receives a stronger signal responsive to the second waveform from the second RFID tag than from the first RFID tag, and wherein the response signals received at the first antenna and the response signals received at the second antenna collide at the time slot;

    isolating, by a first receiver of the RFID reader, the signal from the first RFID tag from the signal from the second RFID tag based at least in part upon orthogonality of the different orientations of the first and second RFID tags and the orthogonality of the first and second waveforms;

    isolating, by a second receiver of the RFID reader, the signal from the second RFID tag from the signal from the first RFID tag based at least in part upon orthogonality of the different orientations of the first and second RFID tags and the orthogonality of the first and second waveforms; and

    decoding a message in the signal from the first RFID tag to recover an identification (ID) of the first RFID tag and a message in the signal from the second RFID tag to recover an ID of the second RFID tag, wherein the signals from the first RFID tag and the second RFID tag are received simultaneously.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×