726 research outputs found
Long term Throughput and Approximate Capacity of Transmitter-Receiver Energy Harvesting Channel with Fading
We first consider an energy harvesting channel with fading, where only the
transmitter harvests energy from natural sources. We bound the optimal long
term throughput by a constant for a class of energy arrival distributions. The
proposed method also gives a constant approximation to the capacity of the
energy harvesting channel with fading. Next, we consider a more general system
where both the transmitter and the receiver employ energy harvesting to power
themselves. In this case, we show that finding an approximation to the optimal
long term throughput is far more difficult, and identify a special case of unit
battery capacity at both the transmitter and the receiver for which we obtain a
universal bound on the ratio of the upper and lower bound on the long term
throughput.Comment: To appear in ICCS 2014, Macau in Nov. 201
On Distributed Power Control for Uncoordinated Dual Energy Harvesting Links: Performance Bounds and Near-Optimal Policies
In this paper, we consider a point-to-point link between an energy harvesting
transmitter and receiver, where neither node has the information about the
battery state or energy availability at the other node. We consider a model
where data is successfully delivered only in slots where both nodes are active.
Energy loss occurs whenever one node turns on while the other node is in sleep
mode. In each slot, based on their own energy availability, the transmitter and
receiver need to independently decide whether or not to turn on, with the aim
of maximizing the long-term time-average throughput. We present an upper bound
on the throughput achievable by analyzing a genie-aided system that has
noncausal knowledge of the energy arrivals at both the nodes. Next, we propose
an online policy requiring an occasional one-bit feedback whose throughput is
within one bit of the upper bound, asymptotically in the battery size. In order
to further reduce the feedback required, we propose a time-dilated version of
the online policy. As the time dilation gets large, this policy does not
require any feedback and achieves the upper bound asymptotically in the battery
size. Inspired by this, we also propose a near-optimal fully uncoordinated
policy. We use Monte Carlo simulations to validate our theoretical results and
illustrate the performance of the proposed policies.Comment: 8 page
Training Optimization for Energy Harvesting Communication Systems
Energy harvesting (EH) has recently emerged as an effective way to solve the
lifetime challenge of wireless sensor networks, as it can continuously harvest
energy from the environment. Unfortunately, it is challenging to guarantee a
satisfactory short-term performance in EH communication systems because the
harvested energy is sporadic. In this paper, we consider the channel training
optimization problem in EH communication systems, i.e., how to obtain accurate
channel state information to improve the communication performance. In contrast
to conventional communication systems, the optimization of the training power
and training period in EH communication systems is a coupled problem, which
makes such optimization very challenging. We shall formulate the optimal
training design problem for EH communication systems, and propose two solutions
that adaptively adjust the training period and power based on either the
instantaneous energy profile or the average energy harvesting rate. Numerical
and simulation results will show that training optimization is important in EH
communication systems. In particular, it will be shown that for short block
lengths, training optimization is critical. In contrast, for long block
lengths, the optimal training period is not too sensitive to the value of the
block length nor to the energy profile. Therefore, a properly selected fixed
training period value can be used.Comment: 6 pages, 5 figures, Globecom 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
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
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