Data transmission method and apparatus in RFID and remote sensor systems
First Claim
1. A method for data transmission in RFID and remote sensor systems having at least one reader and at least one transponder or remote sensor being located in an electromagnetic field of the reader, the method comprising the steps of:
- transmitting a return link header at a beginning of a return link transmission of useful data from a transponder or sensor to a reader, the return link header containing multipart transmission parameters that includes subsymbols, the subsymbols having a time duration; and
modifying the time duration of individual subsymbols to select a data transfer mode from a plurality of different data transfer modes.
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Accused Products
Abstract
A method and apparatus is provided for data transmission in RFID and remote sensor systems with at least one reader and a plurality of transponders or remote sensors being located in an electromagnetic field of the reader, in which a multipart return link header containing transmission parameters for the return link, such as timing or modulation references, is transmitted at the beginning of a return link transmission of useful data from a transponder or sensor to a reader. A relative time duration of individual subsymbols of the return link header is modified to select a data transfer mode from among a number of different data transfer modes. A combination of different return link transmission mechanisms is thereby possible, whereby these are mutually compatible and moreover are simple to realize in terms of circuitry and control engineering.
29 Citations
18 Claims
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1. A method for data transmission in RFID and remote sensor systems having at least one reader and at least one transponder or remote sensor being located in an electromagnetic field of the reader, the method comprising the steps of:
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transmitting a return link header at a beginning of a return link transmission of useful data from a transponder or sensor to a reader, the return link header containing multipart transmission parameters that includes subsymbols, the subsymbols having a time duration; and
modifying the time duration of individual subsymbols to select a data transfer mode from a plurality of different data transfer modes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for selecting a data transfer mode, the method comprising the steps of:
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receiving an end of transmission symbol; and
transmitting a return link header from a transponder, the return link header including a plurality of subsymbols that are each transmitted for a predetermined time period subsequently to one another, wherein the data transfer mode is selected on the basis of a comparison of the predetermined time period of two adjacent subsymbols. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A transponder comprising:
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an antenna; and
circuitry for transmitting a return link header having at least two adjacent subsymbols, wherein data is transmitted by the transponder in either a first data transfer mode or a second data transfer mode, and wherein the first data transfer mode or the second data transfer mode is selected on the basis of a comparison of a transmission duration between two of the subsymbols.
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Specification