# US 10,873,363 B2 · Backscatter devices and network systems incorporating backscatter devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,363 B2 - Document ID: US10873363B2 - Status: Granted - Kind: B2 - Application number: 15/752,214 - Filed: 2016-08-12 - Published: 2020-07-02 - Granted: 2020-12-22 - Earliest claimed: 2015-08-12 - Assignees: University of Washington - Applicants: University of Washington - Inventors: Shyamnath Gollakota; Bryce Kellogg; Vamsi Talla; Joshua R. Smith - Web page: https://patentgrep.com/patent/US10873363B2 ## CPC - H04B 1/40: Circuits - H04B 1/713: using frequency hopping - H04B 5/77: for interrogation - H04B 7/0413: MIMO systems - H04Q 5/22: the subordinate centre not permitting interconnection of subscribers connected thereto - H04W 74/0808: using carrier sensing, e.g. carrier sense multiple access [CSMA] - H04Q 2213/13098: Mobile subscriber - H04Q 2213/1319: Amplifier, attenuation circuit, echo suppressor - H04B: TRANSMISSION - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Examples described herein include devices and systems utilizing backscatter communication to directly generate transmissions in accordance with wireless communication protocols that can be decoded existing devices. Examples include devices that generate 802.11b transmissions using backscatter communication. Examples of network stacks are described which may facilitate backscatter devices to coexist with other devices (e.g. in the ISM band), without incurring, or reducing a need for, the power consumption or carrier sense and medium access control operations. ## Claims ### Claim 1 A backscatter device comprising: an antenna configured to backscatter a carrier signal having a first frequency; baseband circuitry configured to provide data for transmission; a waveform generator configured to provide a square wave having a second frequency, wherein the second frequency is a difference between the first frequency and a third frequency; a sub-carrier phase modulator coupled to the baseband circuitry and the waveform generator, the sub-carrier phase modulator configured to shift the square wave in accordance with the data to provide an output signal; and a switch coupled to the antenna, the switch configured to control the antenna to backscatter the carrier signal in accordance with the output signal such that the first frequency is mixed with the second frequency to transmit the data in a backscatter signal at the third frequency, wherein the backscatter signal is arranged in accordance with a wireless communication protocol implementing phase-shift keying. ### Claim 2 (depends on 1) The backscatter device of claim 1, wherein the backscatter signal is arranged in accordance with a wireless communication protocol implementing amplitude-shift keying. ### Claim 3 (depends on 2) The backscatter device of claim 2, wherein the wireless communication protocol comprises Wi-Fi, ZigBee, SigFox, or combinations thereof. ### Claim 4 (depends on 1) The backscatter device of claim 1, wherein the waveform generator is further configured to provide a waveform, wherein the waveform comprises an analog signal; a multi-level signal, or combinations thereof. ### Claim 5 (depends on 1) The backscatter device of claim 1, wherein the data comprises a Wi-Fi packet. ### Claim 6 (depends on 1) The backscatter device of claim 1, wherein the switch is configured to control the antenna to backscatter the carrier signal in accordance with the output signal to transmit the data at the third frequency and a fourth frequency. ### Claim 7 (depends on 1) The backscatter device of claim 1, further comprising multiple antennas, and wherein the carrier signal is provided using MIMO techniques. ### Claim 8 A backscatter device comprising: an antenna, the antenna configured to backscatter a frequency hopped signal including a first frequency; baseband circuitry configured to provide data for transmission; a waveform generator configured to provide a square wave having a second frequency and further configured to hop the second frequency in accordance with the frequency hopped signal; a sub-carrier phase modulator coupled to the baseband circuitry and the waveform generator, the sub-carrier phase modulator configured to shift the square wave in accordance with the data to provide an output signal; and a switch coupled to the antenna, the switch configured to control the antenna to backscatter the carrier signal in accordance with the output signal such that the first frequency is mixed with the second frequency to transmit the data in a backscatter signal at a third frequency, wherein the backscatter signal is arranged in accordance with a wireless communication protocol implementing phase-shift keying. ### Claim 9 (depends on 8) The backscatter device of claim 8, wherein the waveform generator is further configured to provide a waveform, wherein the waveform comprises a square wave, analog signal, multi-level signal, or combinations thereof. ### Claim 10 (depends on 8) The backscatter device of claim 8, wherein the frequency hopped signal comprises a sequence of frequencies, and wherein the sequence of frequencies is received by the backscatter device over a downlink from a device configured to transmit the carrier signal. ### Claim 11 (depends on 8) The backscatter device of claim 8, wherein the frequency hopped signal comprises a sequence of frequencies, and wherein the backscatter device further comprises a memory configured to store the sequence of frequencies. ### Claim 12 (depends on 11) The backscatter device of claim 11, wherein the sequence of frequencies comprises a pseudorandom sequence. ### Claim 13 (depends on 8) The backscatter device of claim 8, wherein the first frequency is mixed with the second frequency to transmit the data in the backscatter signal at the third frequency, and wherein the backscatter signal comprises a signal in accordance with a wireless communication protocol selected from the group of protocols consisting of Wi-Fi, ZigBee, SigFox, and combinations thereof. ### Claim 14 (depends on 8) The backscatter device of claim 8, further comprising frequency determination circuitry coupled to the antenna, the frequency determination circuitry configured to provide an indication of the second frequency to the waveform generator at least in part by sensing the first frequency of the carrier signal and computing a difference between the first frequency and the third frequency. ### Claim 15 A system comprising: a helper device configured to transmit a carrier signal including a first frequency; a backscatter device configured to backscatter the carrier signal using sub-carrier shift modulation with a square wave having a second frequency, the backscatter device configured to backscatter the carrier signal into a backscatter signal at a third frequency, the third frequency equal to a combination of the first and second frequencies, wherein the backscatter signal is arranged in accordance with a wireless communication protocol implementing phase-shift keying; and a receiver configured to receive the backscatter signal at the third frequency. ### Claim 16 (depends on 15) The system of claim 15, wherein the backscatter device is further configured to provide data in the backscatter signal using amplitude shift keying. ### Claim 17 (depends on 15) The system of claim 15, further comprising a plurality of helper devices including the helper device and a plurality of receivers including the receiver, wherein the helper device is selected from the plurality of helper devices to provide the carrier signal based, at least in part, on a proximity of the helper device to the backscatter device. ### Claim 18 (depends on 17) The system of claim 17, wherein each of the plurality of helper devices is configured to provide the carrier signal in one mode and to receive the backscatter signal in another mode. ### Claim 19 (depends on 15) The system of claim 15, wherein the helper device and the receiver are separate electronic devices. ### Claim 20 (depends on 15) The system of claim 15, wherein the helper device and the receiver are integrated in a same device, the same device including cancellation circuitry configured to cancel the carrier signal at the receiver. ### Claim 21 A backscatter device comprising: an antenna configured to backscatter a carrier signal having a first frequency; baseband circuitry configured to provide data for transmission; a waveform generator configured to provide a waveform having a second frequency, wherein the second frequency is a difference between the first frequency and a third frequency; a sub-carrier phase modulator coupled to the baseband circuitry and the waveform generator, the sub-carrier phase modulator configured to adjust a phase, amplitude, or combinations thereof, of the waveform in accordance with the data to provide an output signal; and a switch coupled to the antenna, the switch configured to control the antenna to backscatter the carrier signal in accordance with the output signal such that the first frequency is mixed with the second frequency to transmit the data in a backscatter signal at the third frequency and a fourth frequency. ### Claim 22 A backscatter device comprising: an antenna, the antenna configured to backscatter a frequency hopped signal having a sequence of frequencies including a first frequency; baseband circuitry configured to provide data for transmission; a waveform generator configured to provide a waveform having a second frequency and further configured to hop the second frequency in accordance with the frequency hopped signal; a sub-carrier phase modulator coupled to the baseband circuitry and the waveform generator, the sub-carrier phase modulator configured to adjust a phase, amplitude, or combinations thereof, of the waveform in accordance with the data to provide an output signal; a switch coupled to the antenna, the switch configured to control the antenna to backscatter the carrier signal in accordance with the output signal such that the first frequency is mixed with the second frequency to transmit the data; and a memory configured to store the sequence of frequencies. ### Claim 23 A backscatter device comprising: an antenna, the antenna configured to backscatter a frequency hopped signal including a first frequency; baseband circuitry configured to provide data for transmission; a waveform generator configured to provide a waveform having a second frequency and further configured to hop the second frequency in accordance with the frequency hopped signal; a sub-carrier phase modulator coupled to the baseband circuitry and the waveform generator, the sub-carrier phase modulator configured to adjust a phase, amplitude, or combinations thereof, of the waveform in accordance with the data to provide an output signal; a switch coupled to the antenna, the switch configured to control the antenna to backscatter the carrier signal in accordance with the output signal such that the first frequency is mixed with the second frequency to transmit the data; and a frequency determination circuitry coupled to the antenna, the frequency determination circuitry configured to provide an indication of the second frequency to the waveform generator at least in part by sensing the first frequency of the carrier signal and computing a difference between the first frequency and the third frequency. ### Claim 24 A system comprising: a helper device configured to transmit a carrier signal including a first frequency; a backscatter device configured to backscatter the carrier signal using sub-carrier modulation with a waveform having a second frequency, the backscatter device configured to backscatter the carrier signal into a backscatter signal at a third frequency, the third frequency equal to a combination of the first and second frequencies; a receiver configured to receive the backscatter signal at the third frequency; and a plurality of helper devices including the helper device and a plurality of receivers including the receiver, wherein the helper device is selected from the plurality of helper devices to provide the carrier signal based, at least in part, on a proximity of the helper device to the backscatter device.