Collaborative rfid reader using code divisional multiple access (cdma) and methods for same
AssigneeCornell University
InventorsEdwin C. KAN, Xiaonan HUI
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Abstract
The present disclosure provides collaborative radiofrequency identification (RFID) readers that employ code division multiple access (CDMA) encoding to simultaneously broadcast to and read responses from tags in an overlapping reading zone with improved data synchronization and read yield rates. In some embodiments, a harmonic backscattering scheme is used to enable the system to have a much higher signal-to-noise ratio (SNR) and sensitivity, while the reader CDMA protocol can be integrated with an initial TDMA polling process or alternative tag CDMA scheme.
Claims10
A method for collaborative RFID readers, comprising:
- providing an RFID reader, the RFID reader having a baseband frequency and being a member of a group of participating RFID readers each being synchronized to the baseband frequency, and wherein the RFID reader is assigned an orthogonal code to produce a code division multiple access (CDMA)-encoded signal, and a set of mutually-orthogonal codes for all participating RFID readers is known to the RFID reader;
- transmitting, using the RFID reader, a CDMA-encoded signal to RFID tags within a reading range of the RFID reader;
- receiving a response signal from an RFID tag within the reading range, wherein the response signal comprises data encoded with an orthogonal code of an RFID reader of the group of participating RFID readers;
- and
- decoding the data of the response signal using the known set of mutually-orthogonal codes.
A collaborative RFID reader, comprising:
- a transmitter having a Tx baseband frequency, wherein the Tx baseband frequency is configured to be synchronized to a Tx baseband frequency of participating RFID readers;
- a non-transient memory configured to store an assigned orthogonal code and a set of mutually-orthogonal codes assigned to all participating RFID readers;
- a processor in electronic communication with the transmitter and the non-transient memory, wherein the processor is programmed to:
- encode data according to the assigned orthogonal code to produce a CDMA-encoded signal;
- and
- transmit the CDMA-encoded signal using the transmitter.
An RFID tag, comprising:
- a non-transient memory configured to store a unique identification code and a set of mutually-orthogonal RFID reader codes;
- and
- an antenna configured for a signal at a first frequency;
- a receiver in electronic communication with the non-transient memory and the first antenna, the receiver configured to receive and decode a reader CDMA-encoded signal from the first antenna using a code of the mutually-orthogonal RFID reader codes.
Dependencies are inferred from the claim text.