3 research outputs found
Transceiver Design for Ambient Backscatter Communication over Frequency-Selective Channels
Existing studies about ambient backscatter communication mostly assume
flat-fading channels. However, frequency-selective channels widely exist in
many practical scenarios. Therefore, this paper investigates ambient
backscatter communication systems over frequency-selective channels. In
particular, we propose an interference-free transceiver design to facilitate
signal detection at the reader. Our design utilizes the cyclic prefix (CP) of
orthogonal frequency-division multiplexing (OFDM) source symbols, which can
cancel the signal interference and thus enhance the detection accuracy at the
reader. Meanwhile, our design leads to no interference on the existing OFDM
communication systems. Next we suggest a chi-square based detector for the
reader and derive the optimal detection threshold. Simulations are then
provided to corroborate our proposed studies.Comment: 5 pages, 5 figures. arXiv admin note: substantial text overlap with
arXiv:1812.1127
Achievable information rates of ambient backscatter communications
Ambient backscatter is an intriguing wireless communication paradigm that
allows small devices to compute and communicate by using only the power they
harvest from radio-frequency (RF) signals in the air. Ambient backscattering
devices reflect existing RF signals emitted by legacy communications systems,
such as digital TV broadcasting, cellular or Wi-Fi ones, which would be
otherwise treated as harmful sources of interference. This paper deals with the
ultimate performance limits of ambient backscatter systems in broadband fading
environments, by considering different amounts of network state information at
the receivers. After introducing a detailed signal model of the relevant
communication links, we study the influence of physical parameters on the
capacity of both legacy and backscatter systems. We find that, under reasonable
operative conditions, a legacy system employing multicarrier modulation can
turn the RF interference arising from the backscatter process into a form of
multipath diversity that can be suitably exploited to noticeably increase its
performance. Moreover, we show that, even when employing simple single-carrier
modulation techniques, the backscatter system can achieve significant data
rates over relatively short distances, especially when the intended recipient
of the backscatter signal is co-located with the legacy transmitter, i.e., they
are on the same machine.Comment: 29 pages, 11 figure
Optimum Multi-Antenna Ambient Backscatter Receiver for General Binary-Modulated Signal
Ambient backscatter communication (AmBC) is becoming increasingly popular for
enabling green communication amidst the continual development of the
Internet-of-things paradigm. Efforts have been put into backscatter signal
detection as the detection performance is limited by the low
signal-to-interference-plus-noise ratio (SINR) of the signal at the receiver.
The low SINR can be improved by adopting a multi-antenna receiver. In this
paper, the optimum multi-antenna receiver that does not impose any constraints
on the types of binary modulation performed by the backscatter device and the
waveform used by the ambient source system is studied. The proposed receiver
owns a simple structure formed by two beamformers. Bit error rate (BER)
performances of the optimum receiver are derived under constant-amplitude
ambient signal and Gaussian-distributed ambient signal. Moreover, to facilitate
the implementation of the optimum receiver, a simplified receiver is proposed
and practical approximations to required beamformers are provided. The derived
optimum receiver avoids the complex direct path interference cancellation and
coherent reception, but exploits the fact that backscatter signal changes the
composite channel impinging at the receiver and the directivity of receiver
antenna array. Comparative simulation results show that the performance of the
optimum receiver achieves the same performance as the coherent receiver even
though it realizes non-coherent reception. The studied receivers provide high
flexibility for implementing simple and low-cost receivers in different AmBC
systems