Array of very light readers for active RFID and location applications

• US 10,534,938 B2
• Filed: 02/25/2016
• Issued: 01/14/2020
• Est. Priority Date: 03/01/2007
• Status: Active Grant

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Zebra Technologies Corporation
• Inventors: Raphaeli, Dani, Kaplan, Gideon, Menkes, Abraham, Sela, Guy, Marinov, Izhar, Ram, Uzi
• Primary Examiner(s): Lim, Steven
• Assistant Examiner(s): Littlejohn, Jr., Mancil
• Application Number:
  US15/053,874
• Publication Number:
  US 20160180121A1
• Time in Patent Office: 1,419 Days
• Field of Search: 340 101- 106
• CPC Class Codes: G06K 7/10019 resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. collision between the communication channels used by wireless communication devices, where the solution is not particularly adapted for RFIDs or the like, H04W74/08
• CPC Class Codes: G06K 7/10306 ultra wide band
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: H04W 74/00 Wireless channel access

Abstract

An example method includes estimating whether a collision occurred between a plurality of wide band response signals, the wide band response signals being responsive to a first interrogation signal transmitted by a first reader; when the collision is estimated to have occurred and the first reader received a first response from a particular tag, transmitting, by the first reader, a second interrogation signal, the second interrogation signal initiating a communication session between the reader and the particular tag; and transmitting, by the first reader, an acknowledgement packet to cause the tag to refrain from responding to a command during the communication session; and a second reader to refrain from interrogating the particular tag during the communication session.

Claims

1. A method comprising:

estimating whether a collision occurred between a plurality of wide band response signals at a first reader, the wide band response signals being responsive to a first interrogation signal transmitted by the first reader;

when the collision between the plurality of wide band response signals at the first reader is estimated to have occurred and the first reader received a first response from a first one of a plurality of tags;

transmitting, by the first reader, a second interrogation signal, the second interrogation signal initiating a communication session between the first reader and the first tag; and

transmitting, by the first reader, an acknowledgement packet to cause;

the first tag to refrain from responding to a command during the communication session; and

a second reader to refrain from interrogating the first tag during the communication session.

2. A method as defined in claim 1, further comprising limiting the first reader to receive replies having a combined reader transmission and tag reply time-of-flight within a predetermined amount of time.

3. A method as defined in claim 1, further comprising determining a round trip delay time of individual ones of the plurality of wide band response signals.

4. A method as defined in claim 1, further comprising estimating a quantity of the plurality of wide band response signals.

5. A system comprising:

a tag configured to receive a first interrogation signal and to transmit a first wide band response signal in response to the first interrogation signal;

a first reader to transmit the first interrogation signal and to receive a plurality of wide band response signals including the first wide band response signal from the tag, the first reader configured to, in response to an estimation that a collision occurred between the plurality of response signals at the first reader;

transmit a second interrogation signal to initiate a communication session between the first reader and the tag; and

transmit an acknowledgment packet to cause the tag to refrain from responding to a command during the communication session; and

a second reader configured to, in response to receiving the acknowledgement packet, refrain from interrogating the tag during the communication session.

6. A system as defined in claim 5, wherein the tag is a wide-band active RFID tag comprising:

a Very-Large-Scale Integration (VLSI) chip integrating an ultra wide band (UWB) front end with a digital transceiver;

a UWB antenna;

a power supply; and

a clock source.

7. A system as defined in claim 5, further comprising a central network controller to dynamically determine overlapping coverage between the first and second readers by analyzing responses of the tag and other tags.

8. A system as defined in claim 5, wherein the first reader is configured to determine a round trip delay time of individual ones of the plurality of wide band response signals.

9. A system as defined in claim 5, wherein the first reader is to estimate a quantity of the plurality of wide band response signals.

10. A first reader, comprising:

communication hardware to;

transmit a first interrogation signal; and

receive a plurality of response signals in response to the first interrogation signal, the plurality of response signals including a first response signal from a tag; and

a processor to;

when a collision is estimated to have occurred between the plurality of response signals;

provide a second interrogation signal to be transmitted by the communication hardware, the second interrogation signal to initiate a communication session between the first reader and the tag; and

provide an acknowledgement packet to be transmitted by the communication hardware, the acknowledgement packet to prohibit;

the tag from responding to a command during the communication session; and

a second reader from interrogating the tag during the communication session.

11. A first reader as defined in claim 10, further comprising:

a controller configured to implement a Media Access Control (MAC) protocol; and

a communication interface subsystem configured to operate with the controller, wherein the communication interface subsystem is to provide connection to a network through a channel separate from the tag.

12. A first reader as defined in claim 11, wherein the communication interface subsystem providing connection to the network includes communication via one or more of WiFi, Wimax, UWB, power lines, Bluetooth®

, or Ethernet.

13. A first reader as defined in claim 10, further comprising a tag module having at least one VLSI chip integrating a UWB front end and digital transceiver.

14. A first reader as defined in claim 10, wherein the processor is to determine a round trip delay time for individual ones of the plurality of response signals.

15. A first reader as defined in claim 10, wherein the processor is to estimate a quantity of the plurality of wide band response signals.