Method, system, and apparatus for binary traversal of a tag population
First Claim
1. A method in a radio frequency identification (RFID) tag device for controlling an operating state of the tag device using a reader, wherein the operating state is chosen from a plurality of possible states, comprising the steps of:
- (a) receiving a symbol from the reader when the operating state is a present state, wherein a first pulse width for the received symbol represents a first data value, and a second pulse width for the received symbol represents a second data value;
(b) determining a new state for the operating state based upon the received symbol and present state; and
(c) transitioning the operating state from the present state to the determined new state.
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Accused Products
Abstract
A method, system, and apparatus for interrogating a radio frequency identification (RFID) tag population are described. Tags are interrogated by a reader. The reader and tags engage in communication according to binary traversal algorithms, where single bit data symbols are exchanged between the reader and tags. Furthermore, a reader implicitly controls the operating state of every tag in the tag population by transmitting a single data symbol. Bit patterns may be collected from the tags by the reader, using a variety of interrogation techniques. In a general interrogation, the reader exchanges symbols with the tag population to interrogate the entire tag population. In a specific interrogation, a reader exchanges symbols with the tag population to target a particular tag identification number. Tags may also be placed in a superposition state by the reader, where they respond whenever a received data symbol matches the next bit of their identification number.
160 Citations
32 Claims
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1. A method in a radio frequency identification (RFID) tag device for controlling an operating state of the tag device using a reader, wherein the operating state is chosen from a plurality of possible states, comprising the steps of:
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(a) receiving a symbol from the reader when the operating state is a present state, wherein a first pulse width for the received symbol represents a first data value, and a second pulse width for the received symbol represents a second data value; (b) determining a new state for the operating state based upon the received symbol and present state; and (c) transitioning the operating state from the present state to the determined new state. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method in a radio frequency identification (RFID) tag device for controlling an operating state of the tag device using a reader, comprising the steps of:
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receiving a symbol from the reader; and determining a new state for the operating state of the tag device, wherein said determining step includes the steps of; (a) allowing the operating state to remain in a first state if the operating state is the first state when the symbol is received, (b) transitioning the operating state to the first state if the operating state is a second state when the symbol is received, (c) transitioning the operating state to a third state if the operating state is a fourth state when the symbol is received, and (d) transitioning the operating state to the first state if the operating state is a fifth state when the symbol is received. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method in a radio frequency identification (RFID) tag device for controlling an operating state of the tag device from a reader, comprising the steps of:
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receiving a symbol from the reader; and determining a new state for the operating state of the tag device, wherein said determining step includes the steps of; (a) if the operating state is a first state when the symbol is received in said receiving step, performing the following steps; (1) transitioning the operating state to a second state if a value of the received symbol is a first data value, and (2) transitioning the operating state to a third state if the value of the received symbol is a second data value; (c) allowing the operating state to remain the third state if the operating state is the third state when the symbol is received in said receiving step; (d) if the operating state is the second state when the symbol is received in said receiving step, performing the following steps; (1) allowing the operating state to remain the second state if the received symbol matches a present tag identification bit, and (2) transitioning the operating state to a fourth state if the received symbol does not match the present tag identification bit; and (e) allowing the operating state to remain the fourth state if the operating state is the fourth state when the symbol is received in said receiving step. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification