2,835 research outputs found
Communicating Using an Energy Harvesting Transmitter: Optimum Policies Under Energy Storage Losses
In this paper, short-term throughput optimal power allocation policies are
derived for an energy harvesting transmitter with energy storage losses. In
particular, the energy harvesting transmitter is equipped with a battery that
loses a fraction of its stored energy. Both single user, i.e. one
transmitter-one receiver, and the broadcast channel, i.e., one
transmitter-multiple receiver settings are considered, initially with an
infinite capacity battery. It is shown that the optimal policies for these
models are threshold policies. Specifically, storing energy when harvested
power is above an upper threshold, retrieving energy when harvested power is
below a lower threshold, and transmitting with the harvested energy in between
is shown to maximize the weighted sum-rate. It is observed that the two
thresholds are related through the storage efficiency of the battery, and are
nondecreasing during the transmission. The results are then extended to the
case with finite battery capacity, where it is shown that a similar
double-threshold structure arises but the thresholds are no longer monotonic. A
dynamic program that yields an optimal online power allocation is derived, and
is shown to have a similar double-threshold structure. A simpler online policy
is proposed and observed to perform close to the optimal policy.Comment: Submitted to IEEE Transactions on Wireless Communications, August
201
Energy Harvesting Wireless Communications: A Review of Recent Advances
This article summarizes recent contributions in the broad area of energy
harvesting wireless communications. In particular, we provide the current state
of the art for wireless networks composed of energy harvesting nodes, starting
from the information-theoretic performance limits to transmission scheduling
policies and resource allocation, medium access and networking issues. The
emerging related area of energy transfer for self-sustaining energy harvesting
wireless networks is considered in detail covering both energy cooperation
aspects and simultaneous energy and information transfer. Various potential
models with energy harvesting nodes at different network scales are reviewed as
well as models for energy consumption at the nodes.Comment: To appear in the IEEE Journal of Selected Areas in Communications
(Special Issue: Wireless Communications Powered by Energy Harvesting and
Wireless Energy Transfer
Trading Wireless Information and Power Transfer: Relay Selection to Minimize the Outage Probability
This paper studies the outage probability minimization problem for a multiple
relay network with energy harvesting constraints. The relays are hybrid nodes
used for simultaneous wireless information and power transfer from the source
radio frequency (RF) signals. There is a trade-off associated with the amount
of time a relay node is used for energy and information transfer. Large
intervals of information transfer implies little time for energy harvesting
from RF signals and thus, high probability of outage events. We propose relay
selection schemes for a cooperative system with a fixed number of RF powered
relays. We address both causal and non-causal channel state information cases
at the relay--destination link and evaluate the trade-off associated with
information/power transfer in the context of minimization of outage
probability.Comment: IEEE GlobalSiP, 201
Energy Harvesting Broadband Communication Systems with Processing Energy Cost
Communication over a broadband fading channel powered by an energy harvesting
transmitter is studied. Assuming non-causal knowledge of energy/data arrivals
and channel gains, optimal transmission schemes are identified by taking into
account the energy cost of the processing circuitry as well as the transmission
energy. A constant processing cost for each active sub-channel is assumed.
Three different system objectives are considered: i) throughput maximization,
in which the total amount of transmitted data by a deadline is maximized for a
backlogged transmitter with a finite capacity battery; ii) energy maximization,
in which the remaining energy in an infinite capacity battery by a deadline is
maximized such that all the arriving data packets are delivered; iii)
transmission completion time minimization, in which the delivery time of all
the arriving data packets is minimized assuming infinite size battery. For each
objective, a convex optimization problem is formulated, the properties of the
optimal transmission policies are identified, and an algorithm which computes
an optimal transmission policy is proposed. Finally, based on the insights
gained from the offline optimizations, low-complexity online algorithms
performing close to the optimal dynamic programming solution for the throughput
and energy maximization problems are developed under the assumption that the
energy/data arrivals and channel states are known causally at the transmitter.Comment: published in IEEE Transactions on Wireless Communication
Hybrid NOMA-TDMA for Multiple Access Channels with Non-Ideal Batteries and Circuit Cost
We consider a multiple-access channel where the users are powered from
batteries having non-negligible internal resistance. When power is drawn from
the battery, a variable fraction of the power, which is a function of the power
drawn from the battery, is lost across the internal resistance. Hence, the
power delivered to the load is less than the power drawn from the battery. The
users consume a constant power for the circuit operation during transmission
but do not consume any power when not transmitting. In this setting, we obtain
the maximum sum-rates and achievable rate regions under various cases. We show
that, unlike in the ideal battery case, the TDMA (time-division multiple
access) strategy, wherein the users transmit orthogonally in time, may not
always achieve the maximum sum-rate when the internal resistance is non-zero.
The users may need to adopt a hybrid NOMA-TDMA strategy which combines the
features of NOMA (non-orthogonal multiple access) and TDMA, wherein a set of
users are allocated fixed time windows for orthogonal single-user and
non-orthogonal joint transmissions, respectively. We also numerically show that
the maximum achievable rate regions in NOMA and TDMA strategies are contained
within the maximum achievable rate region of the hybrid NOMA-TDMA strategy
Wireless body sensor networks for health-monitoring applications
This is an author-created, un-copyedited version of an article accepted for publication in
Physiological Measurement. The publisher is
not responsible for any errors or omissions in this version of the manuscript or any version
derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0967-3334/29/11/R01
- âŠ