Backscattering ambient ism band signals
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.
1. A backscatter tag communication device, comprising:
a receiver configured to receive a first packet comprising a first plurality of codewords, the first packet conforming to a communication protocol defining a second plurality of codewords inclusive of the first plurality of codewords, wherein the second plurality of codewords comprises two or more codewords, wherein the first packet is characterized by a first frequency, and wherein each codeword comprises a plurality of bits;
a codeword translator configured to generate a second packet by, for each respective codeword of the first plurality of codewords and based on a data that the backscatter tag communication device is invoked to transmit:
selecting a target codeword of the second plurality of codewords; and
translating the respective codeword to the target codeword, wherein the target codeword is different from the respective codeword; and
a transmitter configured to transmit the second packet at a second frequency different than the first frequency.
2. The backscatter tag communication device of claim 1 , wherein translating the respective codeword to the target codeword comprises changing a phase of the respective codeword.
3. The backscatter tag communication device of claim 2 , wherein the communication protocol comprises one of ZigBee, WiFi 802.11(g), or WiFi 802.11(n).
4. The backscatter tag communication device of claim 2 , wherein the phase is changed based on a data rate of the transmitter.
5. The backscatter tag communication device of claim 1 , wherein said backscatter tag communication device transmits the second packet during one of a plurality of time slots at random.
6. The backscatter tag communication device of claim 5 , wherein a count of the plurality of time slots is a variable number.
7. The backscatter tag communication device of claim 1 , wherein the first packet has a predefined duration.
8. The backscatter tag communication device of claim 7 , further comprising:
an envelope detector configured to detect a duration of the first packet.
9. The backscatter tag communication device of claim 1 , wherein the backscatter tag communication device is configured to multiply an excitation signal defining the first packet with the data that the backscatter tag communication device seeks to transmit to generate a backscatter tag signal defining the second packet.
10. A method of communication via a backscatter tag, the method comprising:
receiving a first packet comprising a first plurality of codewords, the first packet conforming to a communication protocol defining a second plurality of codewords inclusive of the first plurality of codewords, wherein the second plurality of codewords comprises two or more codewords, wherein the first packet is characterized by a first frequency, and wherein each codeword comprises a plurality of bits;
generating a second packet by, for each respective codeword of the first plurality of codewords and based on a data that the backscatter tag is invoked to transmit:
selecting a target codeword of the second plurality of codewords; and
translating the respective codeword to the target codeword, wherein the target codeword is different from the respective codeword; and
transmitting the second packet at a second frequency different than the first frequency.
11. The method of claim 10 , wherein translating the respective codeword to the target codeword comprises changing a phase of the respective codeword.
12. The method of claim 11 , wherein the communication protocol comprises one of ZigBee, WiFi 802.11(g), or WiFi 802.11(n).
13. The method of claim 11 , wherein the phase is changed based on a data rate of a transmitter transmitting the second packet.
14. The method of claim 10 , further comprising:
transmitting the second packet during one of a plurality of time slots at random.
15. The method of claim 14 , wherein a count of the plurality of time slots is a variable number.
16. The method of claim 10 , wherein the first packet has a predefined duration.
17. The method of claim 16 , wherein the backscatter tag comprises an envelope detector configured to detect a duration of the first packet.
18. The method of claim 10 , further comprising:
multiplying an excitation signal defining the first packet with the data that the backscatter tag seeks to transmit to generate a backscatter tag signal defining the second packet.