Ambient RF backscatter communication for vehicle remote control
First Claim
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1. A communication system for a vehicle comprising:
- a wireless fob carried outside the vehicle comprising an RF-harvesting power supply responsive to ambient RF signals, and comprising a switchable antenna generating a backscatter communication signal;
a receiver in the vehicle adapted to detect the backscatter communication signal from the wireless fob;
a harvesting emulator in the vehicle responsive to the ambient RF signals to duplicate a concurrent response present in the RF-harvesting power supply of the wireless fob; and
a vehicle-powered RF transmitter in the vehicle activated to broadcast energizing RF radiation around the vehicle when the duplicated response is below a threshold.
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Abstract
A vehicle communicates with a remote key fob while ensuring an RF environment is sufficient to maintain adequate power from an RF-harvesting power supply that allows the fob to operate without a battery. The vehicle has a receiver adapted to detect a backscatter communication signal from the fob. A harvesting emulator in the vehicle is responsive to ambient RF around the vehicle to duplicate a concurrent response of the fob power supply. A vehicle-powered RF transmitter is activated to broadcast energizing RF radiation around the vehicle when the duplicated response is below a threshold.
15 Citations
20 Claims
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1. A communication system for a vehicle comprising:
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a wireless fob carried outside the vehicle comprising an RF-harvesting power supply responsive to ambient RF signals, and comprising a switchable antenna generating a backscatter communication signal; a receiver in the vehicle adapted to detect the backscatter communication signal from the wireless fob; a harvesting emulator in the vehicle responsive to the ambient RF signals to duplicate a concurrent response present in the RF-harvesting power supply of the wireless fob; and a vehicle-powered RF transmitter in the vehicle activated to broadcast energizing RF radiation around the vehicle when the duplicated response is below a threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A vehicular communication method comprising:
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operating a backscatter fob to generate a backscatter communication signal using power harvested from a local RF environment including ambient RF signals, wherein the backscatter fob is a portable device carried outside a vehicle; emulating the power harvesting of the fob in a vehicle mounted emulator receiving the ambient RF signals to provide a measured power; and activating a vehicle-powered transmitter to boost the local RF environment when the measured power is below a threshold to increase the power harvested in the fob. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A vehicle comprising:
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a receiver adapted to detect a backscatter communication signal from a wireless fob powered by an RF-harvesting power supply; a harvesting emulator responsive to ambient RF around the vehicle to duplicate a concurrent response of the fob power supply; and a vehicle-powered RF transmitter activated to broadcast energizing RF radiation around the vehicle when the duplicated response is below a threshold; wherein the harvesting emulator periodically re-samples the ambient RF during activation of the RF transmitter to update the duplicated concurrent response unaffected by the energizing RF radiation.
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Specification