Methods and apparatuses to identify devices

摘要

Embodiments of the present invention include systems with Readers and Tags in which a Reader queries the Tags with a parameter that includes a level of probability of reply according to which the Tags individually and randomly decide whether or not to reply. In one embodiment, the Tags can switch between two states: A and B. The query command also specifies a state (A or B) so that only the Tags in the specified state can reply. After successfully sending the Tag identification data from a Tag to the Reader, the Tag switches to the other state from the specified state. In one embodiment, the operations about the two states are symmetric. In one embodiment, the Tags can remember the parameters used in a query so that a short form of query command can be used to repeat the query with the same query parameters.

主权项

1. A Tag responsive to queries from a Reader, the Tag comprising:
an antenna; an Integrated Circuit (IC) coupled to the antenna to: receive from the Reader a first query command, the first query command comprising a first value of a probability parameter and a first state flag for the Tag; to receive a second query command, the second query command comprising a second value of the probability parameter and a second state flag for the Tag, wherein the Tag is configured to be in one of a first state or a second state, and wherein the IC is configured to determine if the state of the Tag matches the first state flag; wherein the IC is configured to reply to the first query command with first handshaking data according to the first value of the probability parameter and ignore the second query command, if the state of the Tag matches the first state flag, wherein the IC is configured to reply to the second query command with second handshaking data according to the second value of the probability parameter and ignore the first query command, if the state of the Tag matches the second state flag, wherein the Tag processes the first and second query commands in a same way with respect to the first and second states.