US 7,068,148 B2 · Method for the efficient reading of a population of radio frequency identification tags with unique identification numbers over a noisy air channel

Abstract

A method for reading and tracking radio frequency identification (RFID) tags in the presence of a noisy air channel is provided. In accordance with the method, a binary tree data structure is used to characterize a plurality of RFID tags, each of which is associated with a unique identification (ID) number. During communication between a tag reader and one or more RFID tags, the tag reader traverses the binary tree, eliminating tags from communication until one tag with a unique ID number is isolated and verified. As the binary tree is traversed, counters associated with each node in the tree are incremented based on tag matches, such that, over time, counters associated with nodes in tag-populated branches will tend to have a high value and counters associated with nodes in unpopulated tree branches will tend to have low values. Where the read process is subject to noise and the tag reader is forced make a decision at a branching node, the tag reader makes a branch prediction based on the current value of the node counters associated with each of the possible alternative branches.

Claims26

Dependent claims

A method for communicating with a plurality of radio frequency identification (RFID) tags, comprising:

(a) receiving at least one symbol from the plurality of RFID tags for a first node in a binary tree having a plurality of nodes wherein each node in said binary tree is associated with a counter;
(b) incrementing the counter associated with the first node in said binary tree when the at least one symbol received from said plurality of RFID tags matches a logical value associated with the counter;
(c) decrementing the counter associated with the first node in said binary tree when the at least one symbol received from said plurality of RFID tags does not match the logical value associated with the counter;
and
(d) selecting a second node in said binary tree based on a value of the counter associated with the first node in said binary tree.

2 more elements

A method in a radio frequency identification (RFID) reader for interrogating a population of tags using binary tree traversal protocol, comprising the steps of:

(a) entering a logical node in a binary tree;
(b) transmitting a symbol to the population of tags;
(c) determining if at least one symbol is received from the population of tags;
(d) if it is determined in step (c) that at least one symbol has been received, determining whether one symbol received from the population of tags corresponds to a first logical value;
(e) if it is determined in step (d) that one symbol received corresponds to a first logical value, incrementing a node counter value associated with the first logical value;
(f) if it is determined in step (d) that one symbol received does not correspond to a first logical value, decrementing the node counter value associated with the first logical value;
(g) if it is determined in step (c) that at least one symbol has been received, determining whether one symbol received from the population of tags corresponds to a second logical value;
(h) if it is determined in step (g) that one symbol received corresponds to a second logical value, incrementing a node counter value associated with the second logical value;
(i) if it is determined in step (g) that one symbol received does not correspond to a first logical value, decrementing the node counter value associated with the second logical value;
(j) selecting which logical value to store as a bit of a tag bit pattern;
(k) storing the selected logical value as the bit of the tag bit pattern;
(l) determining whether the bit pattern is complete;
and
(m) if the bit pattern is not complete;
proceeding to step (a).

12 more elements

A method in a radio frequency identification (RFIID) reader for interrogating a population of tags using binary tree traversal protocol. comprising the steps of:

(a) entering a logical node in a binary tree;
(b) transmitting a symbol to the population of tags;
(c) determining if at least one symbol is received from the population of tags:
(d) if it is determined in step (c) that at least one symbol has been received, adjusting information stored for the logical node , wherein step (d) comprises:
(i) it is determined in step (c) that at least one symbol has been received, determining whether the at least one symbol received from the population of tags corresponds to a first logical value;
(ii) if it is determined in step (d)(i) that the at least one symbol received corresponds to the first logical value, incrementing a node counter value associated with the first logical value;
(iii) if it is determined in step (d)(i) that the at least one symbol received does not correspond to the first logical value, decrementing the node counter value associated with the first logical value;
(iv) if it is determined in step (c) that at least one symbol has been received, determining whether the at least one symbol received from the population of tags corresponds to a second logical value;
(v) if it is determined in step (d)(iv) that the at least one symbol received corresponds to the second logical value, incrementing a node counter value associated with the second logical value;
and
(vi) if it is determined in step (d)(v) that the at least one symbol received does not correspond to the second logical value, decrementing the node counter value associated with the second logical value
(e) selecting which logical value to store as a bit of a tag bit pattern;
(f) storing the selected logical value as the bit of the tag bit pattern;
(g) determining whether the bit pattern is complete;
and
(h) if the bit pattern is not complete:
proceeding to step (a).

14 more elements

Dependencies are inferred from the claim text.

Method for the efficient reading of a population of radio frequency identification tags with unique identification numbers over a noisy air channel

Life of this patent

Method for the efficient reading of a population of radio frequency identification tags with unique identification numbers over a noisy air channel

Life of this patent

Abstract

Claims26