Leland Stanford Junior University

University of Massachusetts

Pengyu Zhang

Dinesh Bharadia

Sachin Katti

Deepak Ganesan

Kiran Joshi

Pan Hu

A backscatter tag device includes, in part, a receiver configured to receive a packet conforming to a communication protocol defining a multitude of codewords, a codeword translator configured to translate at least a first subset of the multitude of codewords disposed in the packet to a second multitude of codewords defined by the protocol in response to a data the backscatter tag is invoked to transmit, and a transmitter configured to transmit the packet supplied by the codeword translator at a frequency different than the first frequency at which the packer is received. The communication protocol may optionally be the 802.11 g/n, ZigBee or the Bluetooth communication protocol.

Backscattering ambient ism band signals

Systems and methods for wireless communication are provided. The systems and methods employ a backscatter tag that is configured to shift an incident carrier signal received by the tag to a different frequency band and then transmitting the frequency-shifted carrier signal to a receiver. The frequency band to which the carrier signal is shifted is a band in which interference is minimal or non-existent. Further, the backscatter tag is able to operate in an ultra-low power manner, thereby allowing the tag to be incorporated into components like on-body sensors so that the tag can embed additional information into the carrier signal for transmission and processing by the receiver. Exemplary electronic circuits and systems that utilize a frequency-shifted Backscatter, as well as methods for implementing a frequency-shifted Backscatter, are also provided.

Systems and methods for backscatter communication

Systems and methods for backscatter communications are provided that employ a backscatter reader to transmit a carrier signal to multiple backscatter tags having heterogeneous hardware and specifications. In response to receiving the carrier, the tags encode data into the received signal and, concurrently, transmit their respective backscattered signal to the reader. The concurrent signals are received by the reader as a combined signal. The reader detects edges in the received signal, based on the corresponding in-phase (I) and quadrature (Q) signals. The edges are then assigned to streams based on the offset or transmission rate of the tags. In some cases, the reader can detect edge collisions. These collisions can be resolved by causing the colliding signals to be retransmitted or by separating the colliding signals. The individual streams corresponding to each of the tags can then be decoded to identify the originally transmitted data from each tag.

Systems and methods for asymmetric backscatter communications

A backscatter tag communicate device includes, in part, a receiver configured to receive a WiFi packet conforming to a communication protocol defining a multitude of codewords, a mapper configured to map at least a first subset of the multitude of codewords disposed in the packet to a second multitude of codewords defined by the protocol, and a frequency shifter configured to shift a frequency of the second multitude of codewords such that the frequency shifted codewords are characterized by a single sideband spectrum. The communication protocol may be the 802.11b communication protocol. The mapper may optionally map the first subset of the multitude of codewords by changing phases of the first subset of the multitude of codewords.

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Palo Alto, CA, United States of America

Pengyu Zhang