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Ambient OFDM Pilot-Aided Delay-Shift Keying and Its Efficient Detection for Ultra Low-Power Communications

This paper proposes delay-shift keying (DSK) based on ambient pilot orthogonal frequency-division multiplexing (OFDM) signals transmitted by existing systems such as IEEE 802.11 and its optimal maximum likelihood (ML) detection for ultra-low-power ambient backscatter communications (AmBCs). To realize the proposed ML detection, we further propose a feasible channel estimation method. Numerical results confirm that our proposed system achieves the lower bit error rate (BER) than conventional AmBC based on well-known energy detection over additive white Gaussian noise (AWGN) and fading channels.