162 research outputs found
A Novel User Pairing Scheme for Functional Decode-and-Forward Multi-way Relay Network
In this paper, we consider a functional decode and forward (FDF) multi-way
relay network (MWRN) where a common user facilitates each user in the network
to obtain messages from all other users. We propose a novel user pairing
scheme, which is based on the principle of selecting a common user with the
best average channel gain. This allows the user with the best channel
conditions to contribute to the overall system performance. Assuming lattice
code based transmissions, we derive upper bounds on the average common rate and
the average sum rate with the proposed pairing scheme. Considering M-ary
quadrature amplitude modulation with square constellation as a special case of
lattice code transmission, we derive asymptotic average symbol error rate (SER)
of the MWRN. We show that in terms of the achievable rates, the proposed
pairing scheme outperforms the existing pairing schemes under a wide range of
channel scenarios. The proposed pairing scheme also has lower average SER
compared to existing schemes. We show that overall, the MWRN performance with
the proposed pairing scheme is more robust, compared to existing pairing
schemes, especially under worst case channel conditions when majority of users
have poor average channel gains.Comment: 30 pages, 6 figures, submitted for journal publicatio
Optimal Compression and Transmission Rate Control for Node-Lifetime Maximization
We consider a system that is composed of an energy constrained sensor node
and a sink node, and devise optimal data compression and transmission policies
with an objective to prolong the lifetime of the sensor node. While applying
compression before transmission reduces the energy consumption of transmitting
the sensed data, blindly applying too much compression may even exceed the cost
of transmitting raw data, thereby losing its purpose. Hence, it is important to
investigate the trade-off between data compression and transmission energy
costs. In this paper, we study the joint optimal compression-transmission
design in three scenarios which differ in terms of the available channel
information at the sensor node, and cover a wide range of practical situations.
We formulate and solve joint optimization problems aiming to maximize the
lifetime of the sensor node whilst satisfying specific delay and bit error rate
(BER) constraints. Our results show that a jointly optimized
compression-transmission policy achieves significantly longer lifetime (90% to
2000%) as compared to optimizing transmission only without compression.
Importantly, this performance advantage is most profound when the delay
constraint is stringent, which demonstrates its suitability for low latency
communication in future wireless networks.Comment: accepted for publication in IEEE Transactions on Wireless
Communicaiton
Underlay Drone Cell for Temporary Events: Impact of Drone Height and Aerial Channel Environments
Providing seamless connection to a large number of devices is one of the
biggest challenges for the Internet of Things (IoT) networks. Using a drone as
an aerial base station (ABS) to provide coverage to devices or users on ground
is envisaged as a promising solution for IoT networks. In this paper, we
consider a communication network with an underlay ABS to provide coverage for a
temporary event, such as a sporting event or a concert in a stadium. Using
stochastic geometry, we propose a general analytical framework to compute the
uplink and downlink coverage probabilities for both the aerial and the
terrestrial cellular system. Our framework is valid for any aerial channel
model for which the probabilistic functions of line-of-sight (LOS) and
non-line-of-sight (NLOS) links are specified. The accuracy of the analytical
results is verified by Monte Carlo simulations considering two commonly adopted
aerial channel models. Our results show the non-trivial impact of the different
aerial channel environments (i.e., suburban, urban, dense urban and high-rise
urban) on the uplink and downlink coverage probabilities and provide design
guidelines for best ABS deployment height.Comment: This work is accepted to appear in IEEE Internet of Things Journal
Special Issue on UAV over IoT. Copyright may be transferred without notice,
after which this version may no longer be accessible. arXiv admin note: text
overlap with arXiv:1801.0594
Secure Communication with a Wireless-Powered Friendly Jammer
In this paper, we propose to use a wireless-powered friendly jammer to enable
secure communication between a source node and destination node, in the
presence of an eavesdropper. We consider a two-phase communication protocol
with fixed-rate transmission. In the first phase, wireless power transfer is
conducted from the source to the jammer. In the second phase, the source
transmits the information-bearing signal under the protection of a jamming
signal sent by the jammer using the harvested energy in the first phase. We
analytically characterize the long-time behavior of the proposed protocol and
derive a closed-form expression for the throughput. We further optimize the
rate parameters for maximizing the throughput subject to a secrecy outage
probability constraint. Our analytical results show that the throughput
performance differs significantly between the single-antenna jammer case and
the multi-antenna jammer case. For instance, as the source transmit power
increases, the throughput quickly reaches an upper bound with single-antenna
jammer, while the throughput grows unbounded with multi-antenna jammer. Our
numerical results also validate the derived analytical results.Comment: accepted for publication in IEEE Transactions on Wireless
Communication
Power Beacon-Assisted Millimeter Wave Ad Hoc Networks
Deployment of low cost power beacons (PBs) is a promising solution for
dedicated wireless power transfer (WPT) in future wireless networks. In this
paper, we present a tractable model for PB-assisted millimeter wave (mmWave)
wireless ad hoc networks, where each transmitter (TX) harvests energy from all
PBs and then uses the harvested energy to transmit information to its desired
receiver. Our model accounts for realistic aspects of WPT and mmWave
transmissions, such as power circuit activation threshold, allowed maximum
harvested power, maximum transmit power, beamforming and blockage. Using
stochastic geometry, we obtain the Laplace transform of the aggregate received
power at the TX to calculate the power coverage probability. We approximate and
discretize the transmit power of each TX into a finite number of discrete power
levels in log scale to compute the channel and total coverage probability. We
compare our analytical predictions to simulations and observe good accuracy.
The proposed model allows insights into effect of system parameters, such as
transmit power of PBs, PB density, main lobe beam-width and power circuit
activation threshold on the overall coverage probability. The results confirm
that it is feasible and safe to power TXs in a mmWave ad hoc network using PBs.Comment: This work has been submitted to the IEEE for possible publication.
Copyright may be transferred without notice, after which this version may no
longer be accessibl
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