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US 10,652,073 B2Granted
Backscatter devices and systems providing backscattered signals including OFDM packets
AssigneeUniversity of Washington
InventorsVamsi Talla, Joshua R. Smith, Shyamnath Gollakota, Bryce Kellogg
Life of this patent
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Abstract
Examples described herein include backscatter devices which may transmit orthogonal frequency division multiplexing (OFDM) signals. Techniques for complex analog backscatter are described. Examples of impedance circuitry are described which may be used to provide real and imaginary components of impedance in accordance with inphase and quadrature bits.
Claims20
A backscatter device comprising:
- an antenna;
- baseband circuitry configured to provide inphase bits and quadrature bits corresponding to data for transmission, wherein the baseband circuitry includes a first combiner configured to upconvert by combining at least some of the data with a first subcarrier square wave and a second combiner configured to upconvert at least some of the data with a second subcarrier square wave having a 90 degree phase shift from the first subcarrier square wave;
- first circuitry coupled to the antenna and the baseband circuitry and configured to provide a real component of antenna impedance corresponding to the inphase bits;
- and
- second circuitry coupled to the antenna and the baseband circuitry and configured to provide an imaginary component of the antenna impedance corresponding to the quadrature bits, and wherein the backscatter device is configured to provide a backscatter signal including orthogonal frequency division multiplexing (OFDM) packets in accordance with the inphase bits and the quadrature bits.
2 more elements
A backscatter device comprising:
- an antenna;
- baseband circuitry configured to provide inphase bits and quadrature bits corresponding to data for transmission;
- first circuitry coupled to the antenna and the baseband circuitry and configured to provide a real component of antenna impedance corresponding to the inphase bits;
- and
- second circuitry coupled to the antenna and the baseband circuitry and configured to provide an imaginary component of the antenna impedance corresponding to the quadrature bits, wherein the first circuitry comprises a transistor coupled to the antenna and wherein the transistor includes a gate configured to receive a voltage based on an analog conversion of the inphase bits, and wherein the backscatter device is configured to provide a backscatter signal including orthogonal frequency division multiplexing (OFDM) packets in accordance with the inphase bits and the quadrature bits.
2 more elements
A backscatter device comprising:
- an antenna;
- baseband circuitry configured to provide inphase bits and quadrature bits corresponding to data for transmission;
- first circuitry coupled to the antenna and the baseband circuitry and configured to provide a real component of antenna impedance corresponding to the inphase bits;
- and
- second circuitry coupled to the antenna and the baseband circuitry and configured to provide an imaginary component of the antenna impedance corresponding to the quadrature bits, wherein the second circuitry comprises a transistor coupled to the antenna and a capacitor coupled between the antenna and a reference voltage, wherein the transistor includes a gate configured to receive a voltage based on an analog conversion of the quadrature bits, and wherein the backscatter device is configured to provide a backscatter signal including orthogonal frequency division multiplexing (OFDM) packets in accordance with the inphase bits and the quadrature bits.
2 more elements
A system comprising:
- a helper device configured to transmit a carrier signal;
- and
- a backscatter device configured to receive the carrier signal, the backscatter device comprising:
- an antenna positioned such that the carrier signal is incident on the antenna;
- baseband circuitry configured to provide inphase bits and quadrature bits based on data for transmission, wherein the baseband circuitry includes an analog to digital converter configured to convert the inphase and quadrature bits to converted analog inphase and quadrature bits;
- and
- impedance circuitry configured to provide a real component of antenna impedance corresponding to the inphase bits and a complex component of the antenna impedance corresponding to the quadrature bits, such that the backscatter device is configured to backscatter the carrier signal to form a backscatter signal including orthogonal frequency division multiplexing (OFDM) packets, and wherein the impedance circuitry is further configured to receive the converted analog inphase and quadrature bits as input.
4 more elements
A system comprising:
- a helper device configured to transmit a carrier signal;
- and
- a backscatter device comprising:
- an antenna positioned such that the carrier signal is incident on the antenna;
- baseband circuitry configured to provide inphase bits and quadrature bits based on data for transmission;
- and
- impedance circuitry configured to provide a real component of antenna impedance corresponding to the inphase bits and a complex component of the antenna impedance corresponding to the quadrature bits, such that the backscatter device is configured to backscatter the carrier signal to form a backscatter signal including orthogonal frequency division multiplexing (OFDM) packets, wherein the baseband circuitry is configured to provide the inphase and quadrature bits as digital bits to the impedance circuitry.
4 more elements
A method comprising:
- generating data for transmission at a backscatter device;
- performing baseband operations on the data to generate inphase and quadrature bits corresponding to the data;
- and
- modulating an impedance of an antenna to backscatter an incident carrier signal in accordance with the inphase and quadrature bits to provide a backscattered signal including OFDM packets corresponding to the data, wherein said modulating the impedance comprises coupling an amount of resistance to the antenna based on the inphase bits.
1 more element
A method of comprising:
- generating data for transmission at a backscatter device;
- performing baseband operations on the data to generate inphase and quadrature bits corresponding to the data;
- and
- modulating an impedance of an antenna to backscatter an incident carrier signal in accordance with the inphase and quadrature bits to provide a backscattered signal including OFDM packets corresponding to the data, wherein said modulating the impedance comprises coupling an amount of capacitance to the antenna based on the quadrature bits.
1 more element
Dependencies are inferred from the claim text.