193 research outputs found
An Analog Baseband Approach for Designing Full-Duplex Radios
Recent wireless testbed implementations have proven that full-duplex
communication is in fact possible and can outperform half-duplex systems. Many
of these implementations modify existing half-duplex systems to operate in
full-duplex. To realize the full potential of full-duplex, radios need to be
designed with self-interference in mind. In our work, we use an experimental
setup with a patch antenna prototype to characterize the self-interference
channel between two radios. In doing so, we form an analytical model to design
analog baseband cancellation techniques. We show that our cancellation scheme
can provide up to 10 dB improved signal strength, 2.5 bps/Hz increase in rate,
and a 10,000 improvement in BER as compared to the RF only cancellation
provided by the patch antenna.Comment: 5 pages, 8 figures, to appear in 2013 Asilomar Conference proceeding
Cancellation of Power Amplifier Induced Nonlinear Self-Interference in Full-Duplex Transceivers
Recently, full-duplex (FD) communications with simultaneous transmission and
reception on the same channel has been proposed. The FD receiver, however,
suffers from inevitable self-interference (SI) from the much more powerful
transmit signal. Analogue radio-frequency (RF) and baseband, as well as digital
baseband, cancellation techniques have been proposed for suppressing the SI,
but so far most of the studies have failed to take into account the inherent
nonlinearities of the transmitter and receiver front-ends. To fill this gap,
this article proposes a novel digital nonlinear interference cancellation
technique to mitigate the power amplifier (PA) induced nonlinear SI in a FD
transceiver. The technique is based on modeling the nonlinear SI channel, which
is comprised of the nonlinear PA, the linear multipath SI channel, and the RF
SI canceller, with a parallel Hammerstein nonlinearity. Stemming from the
modeling, and appropriate parameter estimation, the known transmit data is then
processed with the developed nonlinear parallel Hammerstein structure and
suppressed from the receiver path at digital baseband. The results illustrate
that with a given IIP3 figure for the PA, the proposed technique enables higher
transmit power to be used compared to existing linear SI cancellation methods.
Alternatively, for a given maximum transmit power level, a lower-quality PA
(i.e., lower IIP3) can be used.Comment: To appear in proceedings of the 2013 Asilomar Conference on Signals,
Systems & Computer
Self-Interference Cancellation with Nonlinear Distortion Suppression for Full-Duplex Systems
In full-duplex systems, due to the strong self-interference signal, system
nonlinearities become a significant limiting factor that bounds the possible
cancellable self-interference power. In this paper, a self-interference
cancellation scheme for full-duplex orthogonal frequency division multiplexing
systems is proposed. The proposed scheme increases the amount of cancellable
self-interference power by suppressing the distortion caused by the transmitter
and receiver nonlinearities. An iterative technique is used to jointly estimate
the self-interference channel and the nonlinearity coefficients required to
suppress the distortion signal. The performance is numerically investigated
showing that the proposed scheme achieves a performance that is less than 0.5dB
off the performance of a linear full-duplex system.Comment: To be presented in Asilomar Conference on Signals, Systems &
Computers (November 2013
On the Achievable Rates of Multihop Virtual Full-Duplex Relay Channels
We study a multihop "virtual" full-duplex relay channel as a special case of
a general multiple multicast relay network. For such channel,
quantize-map-and-forward (QMF) (or noisy network coding (NNC)) achieves the
cut-set upper bound within a constant gap where the gap grows {\em linearly}
with the number of relay stages . However, this gap may not be negligible
for the systems with multihop transmissions (i.e., a wireless backhaul
operating at higher frequencies). We have recently attained an improved result
to the capacity scaling where the gap grows {\em logarithmically} as ,
by using an optimal quantization at relays and by exploiting relays' messages
(decoded in the previous time slot) as side-information. In this paper, we
further improve the performance of this network by presenting a mixed scheme
where each relay can perform either decode-and-forward (DF) or QMF with
possibly rate-splitting. We derive the achievable rate and show that the
proposed scheme outperforms the QMF-optimized scheme. Furthermore, we
demonstrate that this performance improvement increases with .Comment: To be presented at ISIT 201
Secure Full-Duplex Device-to-Device Communication
This paper considers full-duplex (FD) device-to-device (D2D) communications
in a downlink MISO cellular system in the presence of multiple eavesdroppers.
The D2D pair communicate sharing the same frequency band allocated to the
cellular users (CUs). Since the D2D users share the same frequency as the CUs,
both the base station (BS) and D2D transmissions interfere each other. In
addition, due to limited processing capability, D2D users are susceptible to
external attacks. Our aim is to design optimal beamforming and power control
mechanism to guarantee secure communication while delivering the required
quality-of-service (QoS) for the D2D link. In order to improve security,
artificial noise (AN) is transmitted by the BS. We design robust beamforming
for secure message as well as the AN in the worst-case sense for minimizing
total transmit power with imperfect channel state information (CSI) of all
links available at the BS. The problem is strictly non-convex with infinitely
many constraints. By discovering the hidden convexity of the problem, we derive
a rank-one optimal solution for the power minimization problem.Comment: Accepted in IEEE GLOBECOM 2017, Singapore, 4-8 Dec. 201
Secure Full-Duplex Device-to-Device Communication
This paper considers full-duplex (FD) device-to-device (D2D) communications
in a downlink MISO cellular system in the presence of multiple eavesdroppers.
The D2D pair communicate sharing the same frequency band allocated to the
cellular users (CUs). Since the D2D users share the same frequency as the CUs,
both the base station (BS) and D2D transmissions interfere each other. In
addition, due to limited processing capability, D2D users are susceptible to
external attacks. Our aim is to design optimal beamforming and power control
mechanism to guarantee secure communication while delivering the required
quality-of-service (QoS) for the D2D link. In order to improve security,
artificial noise (AN) is transmitted by the BS. We design robust beamforming
for secure message as well as the AN in the worst-case sense for minimizing
total transmit power with imperfect channel state information (CSI) of all
links available at the BS. The problem is strictly non-convex with infinitely
many constraints. By discovering the hidden convexity of the problem, we derive
a rank-one optimal solution for the power minimization problem.Comment: Accepted in IEEE GLOBECOM 2017, Singapore, 4-8 Dec. 201
Throughput Analysis for Wireless Networks with Full-Duplex Radios
This paper investigates the throughput for wireless network with full-duplex
radios using stochastic geometry. Full-duplex (FD) radios can exchange data
simultaneously with each other. On the other hand, the downside of FD
transmission is that it will inevitably cause extra interference to the network
compared to half-duplex (HD) transmission. In this paper, we focus on a
wireless network of nodes with both HD and FD capabilities and derive and
optimize the throughput in such a network. Our analytical result shows that if
the network is adapting an ALOHA protocol, the maximal throughput is always
achieved by scheduling all concurrently transmitting nodes to work in FD mode
instead of a mixed FD/HD mode or HD mode regardless of the network
configurations. Moreover, the throughput gain of using FD transmission over HD
transmission is analytically lower and upper bounded.Comment: 4 figure
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