Low power wireless communication utilizing OFDM backchannels
First Claim
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1. A method for encoding a message in a signal transmitted in accordance with an orthogonal frequency-division multiplexing (OFDM), comprising:
- identifying, by a transmitter, a subset of subcarrier symbols from which to create an OFDM symbol, where the subset of subcarrier symbols is selected from a finite symbol space for orthogonal frequency-division multiplexing and produces a signal that is demodulated by a receiver that does not comply with OFDM;
receiving, by the transmitter, backchannel data to be transmitted in accordance with OFDM;
encoding, by the transmitter, the backchannel data using the subset of subcarrier symbols; and
transmitting, by the transmitter, the encoded backchannel data across a wireless network using orthogonal frequency-division multiplexing.
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Abstract
An innovative software-defined backchannel communication scheme is provided for use in ultra-low power devices. The technique enables interconnecting heterogeneous devices through a WiFi backchannel that can be realized with existing infrastructure without any hardware modifications. The backchannel communication scheme can also be extended to other OFDM based communication systems, such as cellular 4G LTE.
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Citations
19 Claims
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1. A method for encoding a message in a signal transmitted in accordance with an orthogonal frequency-division multiplexing (OFDM), comprising:
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identifying, by a transmitter, a subset of subcarrier symbols from which to create an OFDM symbol, where the subset of subcarrier symbols is selected from a finite symbol space for orthogonal frequency-division multiplexing and produces a signal that is demodulated by a receiver that does not comply with OFDM; receiving, by the transmitter, backchannel data to be transmitted in accordance with OFDM; encoding, by the transmitter, the backchannel data using the subset of subcarrier symbols; and transmitting, by the transmitter, the encoded backchannel data across a wireless network using orthogonal frequency-division multiplexing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for encoding a message in a signal transmitted in accordance with an orthogonal frequency-division multiplexing (OFDM), comprising:
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receiving, by a transmitter, backchannel data to be transmitted in accordance with orthogonal frequency-division multiplexing; encoding, by the transmitter, the backchannel data by assigning quadrature amplitude modulation (QAM) symbols with a substantially constant phase rotation rate across subcarriers of an OFDM symbol, thereby forming one or more the one or more pulses in time domain of the OFDM symbol; transmitting, by the transmitter, the encoded backchannel data across a wireless network using orthogonal frequency-division multiplexing; receiving, by a receiver, the encoded backchannel data transmitted by the transmitter; and decoding, by the receiver, the encoded backchannel data, wherein the receiver does not operate in accordance with OFDM. - View Dependent Claims (16, 17, 18)
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19. A method for encoding a message in a signal transmitted in accordance with an orthogonal frequency-division multiplexing (OFDM), comprising:
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receiving, by a transmitter, backchannel data to be transmitted in accordance with orthogonal frequency-division multiplexing; encoding, by the transmitter, the backchannel data by assigning quadrature amplitude modulation (QAM) symbols with varying amplitude across subcarriers of an OFDM symbol, thereby modulating frequency of the OFDM symbol; transmitting, by the transmitter, the encoded backchannel data across a wireless network using orthogonal frequency-division multiplexing; receiving, by a receiver, the encoded backchannel data transmitted by the transmitter; and decoding, by the receiver, the encoded backchannel data, wherein the receiver does not operate in accordance with OFDM.
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Specification