Method and system for distance determination of RF tags
First Claim
Patent Images
1. A method for communicating between a reader and a plurality of RF tags, comprising the steps of:
- (a) transmitting a wide band broadcast interrogation signal by a reader;
(b) waiting to receive said wide band broadcast interrogation signal by the plurality of RF tags;
(c) upon receiving said wide band broadcast interrogation signal by a plurality of said RF tags and in response to said wide band broadcast interrogation signal transmitting a plurality of wide band response signals respectively from said RF tags,(d) receiving said wide band response signals by said reader, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pulses wherein at least two of said wide band response signals are overlapping wide band response signals, wherein said overlapping wide band response signals are distinguishable when each of said pulses of each of said wide band response signals is detectable during the time intervals between the pulses of all other said overlapping wide band response signals;
(i) detecting by said reader and thereby distinguishing said sequences of pulses of said overlapping wide band response signals(ii) estimating by said reader the number of wide band response signals transmitted by said tags in response to said wide band broadcast interrogation signal,(iii) analyzing by said reader said distinguishable wide band response signals in order to determine their round trip delay,(e) testing by said reader a predefined statistical criterion indicative of the collision probability of said wide band response signals and according to the result of said testing transmitting by said reader at least one additional wide band broadcast interrogation signal, whereby each said additional wide band broadcast interrogation signal is followed by repeating the steps of said tags said transmitting in response to said additional wide band broadcast interrogation signal and said reader receiving, detecting, estimating, analyzing, testing and transmitting at least one additional wide band broadcast interrogation signal, wherein the collision probability is based at least in part on the number of overlapping wide band response signals, the duration of said pulses and the time interval between said pluses.
10 Assignments
0 Petitions
Accused Products
Abstract
The present invention relates to a method and system (10) for distance determination of RF tags (4) and its applications based on measuring the round trip delay, avoiding deterministic collisions between a plurality of wide band response signals transmitted by the tags (4) by adding a pseudo-random time delay to the wide band response signal, and iteratively reducing the collision probability between plurality of wide band response signals.
-
Citations
124 Claims
-
1. A method for communicating between a reader and a plurality of RF tags, comprising the steps of:
-
(a) transmitting a wide band broadcast interrogation signal by a reader; (b) waiting to receive said wide band broadcast interrogation signal by the plurality of RF tags; (c) upon receiving said wide band broadcast interrogation signal by a plurality of said RF tags and in response to said wide band broadcast interrogation signal transmitting a plurality of wide band response signals respectively from said RF tags, (d) receiving said wide band response signals by said reader, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pulses wherein at least two of said wide band response signals are overlapping wide band response signals, wherein said overlapping wide band response signals are distinguishable when each of said pulses of each of said wide band response signals is detectable during the time intervals between the pulses of all other said overlapping wide band response signals; (i) detecting by said reader and thereby distinguishing said sequences of pulses of said overlapping wide band response signals (ii) estimating by said reader the number of wide band response signals transmitted by said tags in response to said wide band broadcast interrogation signal, (iii) analyzing by said reader said distinguishable wide band response signals in order to determine their round trip delay, (e) testing by said reader a predefined statistical criterion indicative of the collision probability of said wide band response signals and according to the result of said testing transmitting by said reader at least one additional wide band broadcast interrogation signal, whereby each said additional wide band broadcast interrogation signal is followed by repeating the steps of said tags said transmitting in response to said additional wide band broadcast interrogation signal and said reader receiving, detecting, estimating, analyzing, testing and transmitting at least one additional wide band broadcast interrogation signal, wherein the collision probability is based at least in part on the number of overlapping wide band response signals, the duration of said pulses and the time interval between said pluses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
-
-
43. A system for communicating between a reader and a plurality of RF tags, the system comprising:
-
(a) the reader which transmits a wide band broadcast interrogation signal, (b) the tags which wait to receive said wide band broadcast interrogation signal, (c) the tags receive said wide band broadcast interrogation signal and in response transmit respectively a plurality of wide band response signals, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pulses, (d) the reader receives said wide band response signals, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pulses wherein said wide band response signals include overlapping wide band response signals, wherein said overlapping wide band response signals are distinguishable when each of said pulses of each of said wide band response signals is detectable during the time intervals between the pulses of all other said overlapping wide band response signals and (i) said reader detects and distinguishes the overlapping pulse sequences included in said overlapping wide band response signals (ii) said reader estimates the number of wide band response signals to said wide band broadcast interrogation signal, (iii) said reader analyzes and thereby distinguishes between said overlapping wide band response signals in order to determine their round trip delay, (e) said reader tests a predefined statistical criterion indicative of the collision probability of said at least one wide hand response signal and according to the result of the test said reader transmits at least one additional wide band broadcast interrogation signal, wherein the collision probability is based at least in part on the number of overlapping wide band response signals, the duration of said pulses and the time interval between said pulses. - View Dependent Claims (44)
-
-
45. A method for defining a programmable reader cell in RFID system, comprising the steps of:
-
(a) transmitting a wide band broadcast interrogation signal, by a reader, (b) a plurality of tags waiting to receive said wide band broadcast interrogation signal, (c) said tags receiving said wide band broadcast interrogation signal and in response transmitting respectively a plurality of wide band response signals, (d) receiving by said reader said wide band response signals, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pulses wherein said wide band response signals received by said reader include overlapping wide band response signals, wherein said overlapping wide band response signals are distinguishable when each of said pulses of each of said wide bhand response signals is detectable during the time intervals between the pulses of all other said overlapping wide band response signals; (e) detecting by said reader and thereby distinguishing the pulse sequences included in said overlapping wide band response signal and deciding whether one or more tags answered said wide band broadcast interrogation signal, (f) analyzing by said reader the at least one detected wide band response signal, in order to determine the round trip delay of said at least one detected wide band response signal, (g) said reader comparing a predefined threshold to said round trip delay of at least one of said at least one wide band response signal received by said reader, and performing a task with tags having round trip delay that is passing said predefined threshold test. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82)
-
-
83. A system for defining a programmable reader cell in RFID system, comprising:
-
(a) a reader which transmits a wide band broadcast interrogation signal, (b) a plurality of tags which wait to receive said wide band broadcast interrogation signal, (c) the tags wait to receive said wide band broadcast interrogation signal and in response to said wide band broadcast interrogation signal transmit respectively a plurality of wide band response signals, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pluses; (d) said reader receives said wide band response signals, wherein said wide band response signals include overlapping wide band response signals, wherein said overlapping wide band response signals are distinguishable when each of said pulses of each of said wide band response signals is detectable during the time intervals between the pulses of all other said overlapping wide band response signals; (e) said reader detects and distinguishes the overlapping pulse sequences included in said overlapping wide band response signals, and decides whether one or more tags answered said wide band broadcast interrogation signal, (f) said reader analyzes the at least one detected wide band response signal, in order to determine its round trip delay, (g) said reader compares a predefined threshold to said round trip delay of said at least one detected wide band response signal, and performs a task with at least a portion of said tags having round trip delay that passes said predefined threshold test.
-
-
84. In an RFID system including at least two readers and a plurality of RF tags, a method for locating the position of at least one of the RF tags in relation to the respective positions of the at least two readers, the method comprising the steps of:
-
(a) transmitting respectively wide band broadcast interrogation signals, by said at least two readers, (b) the tags waiting to receive said wide band broadcast interrogation signals, (c) in response to said wide band broadcast interrogation signals transmitting respectively wide band response signals, by said at least one tag, in response to each of said received wide band broadcast interrogation signals, wherein each of said wide band response signals includes respective identification information about the interrogating reader and about the at least one RF tag, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pulses; (d) receiving respectively, at least one of said wide band response signals at each of said at least two readers, wherein said at least one wide band response signals respectively received by said readers includes overlapping wide band response signals from the RF tags, wherein said overlapping wide band response signals are distinguishable when each of said pulses of each of said wide band response signals is detectable during the time intervals between the pulses of all other said overlapping wide band response signals; (e) detecting by distinguishing said at least one wide band response signal from said overlapping wide band response signals at each of said at least two readers, deciding whether one or more of the RF tags answered its wide band broadcast interrogation signal, and analyzing said at least one wide band response signal, in order to determine the round trip delay to and from the at least one RF tag and said identification information thereof, (f) transferring, from each of said at least two readers, distance and said identification information of the at least one RF tags and of said reader to a central processing unit, (g) by using the information transferred from said at least two readers, locating the position of the at least one RF tag in relation to the respective positions of said at least two readers, wherein said locating is performed by said central processing unit. - View Dependent Claims (85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123)
-
-
124. An RFID system including at least two readers and a plurality of RF tags, the system for locating the position of at least one of the RF tags in relation to the relative positions of the at least two readers, the system comprising:
-
(a) each of said at least two readers transmits a wide band broadcast interrogation signal, (b) the RF tags waits to receive said wide band broadcast interrogation signals, (c) the RF tags transmit a wide band response signal to each of said wide band broadcast interrogation signals received, wherein each of said wide band response signals includes identification information about the interrogating reader and about said transmitting RF tag, wherein said wide band response signals each include a sequence of pulses, wherein the duration of said pulses is much less than the time interval between said pulses; (d) each of said at least two readers receives at least one of said wide band response signals, wherein said at least one wide band response signal received by said readers include overlapping wide band response signals, wherein said overlapping wide band response signal are distinguishable when each of said pulses of each of said wide band response signals is detectable during the time intervals between the pulses of all other said overlapping wide band response signals; (e) each of said at least two readers detects said at least one wide band response signal, decides whether the at least one of the RF tags answered its wide band broadcast interrogation signal, and analyzes said at least one wide band response signal, transmitted by said at least one RF tag, in order to determine the round trip delay to and from the at least one RF tag and said identification information thereof, (f) each one of said at least two readers transfers distance and identity information of said at least one RF tag and of said reader itself to a central processing unit, (g) by using the information transferred from said at least two readers, said central processing unit locates the position of said at least one tag in relation to the relative positions of said at least two readers.
-
Specification