Backscatter devices and systems providing backscattered signals including OFDM packets
First Claim
Patent Images
1. 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.
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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.
130 Citations
20 Claims
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1. A backscatter device comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A backscatter device comprising:
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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.
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8. A backscatter device comprising:
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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.
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9. A system comprising:
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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. - View Dependent Claims (10, 11, 12)
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13. A system comprising:
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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. - View Dependent Claims (14, 15, 16)
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17. A method comprising:
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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. - View Dependent Claims (18, 19)
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20. A method of comprising:
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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.
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Specification