4 research outputs found
Energy Harvesting for Secure OFDMA Systems
Energy harvesting and physical-layer security in wireless networks are of
great significance. In this paper, we study the simultaneous wireless
information and power transfer (SWIPT) in downlink orthogonal
frequency-division multiple access (OFDMA) systems, where each user applies
power splitting to coordinate the energy harvesting and information decoding
processes while secrecy information requirement is guaranteed. The problem is
formulated to maximize the aggregate harvested power at the users while
satisfying secrecy rate requirements of all users by subcarrier allocation and
the optimal power splitting ratio selection. Due to the NP-hardness of the
problem, we propose an efficient iterative algorithm. The numerical results
show that the proposed method outperforms conventional methods.Comment: Accepted by WCSP 201
Achievable Secrecy Rates of an Energy Harvesting Device with a Finite Battery
In this paper, we investigate the achievable secrecy rates in an Energy Harvesting communication system composed of one transmitter and multiple receivers. In particular, because of the energy constraints and the channel conditions, it is important to understand when a device should transmit or not and how much power should be used. We introduce the Optimal Secrecy Policy in several scenarios. We show that, if the receivers demand high secrecy rates, then it is not always possible to satisfy all their requests. Thus, we introduce a scheme that chooses which receivers should be discarded. Also, we study how the system is influenced by the Channel State Information and, in particular, how the knowledge of the eavesdropper's channel changes the achievable rates
Achievable Secrecy Rates of an Energy Harvesting Device
The secrecy rate represents the amount of information per unit time that can
be securely sent on a communication link. In this work, we investigate the
achievable secrecy rates in an energy harvesting communication system composed
of a transmitter, a receiver and a malicious eavesdropper. In particular,
because of the energy constraints and the channel conditions, it is important
to understand when a device should transmit and to optimize how much power
should be used in order to improve security. Both full knowledge and partial
knowledge of the channel are considered under a Nakagami fading scenario. We
show that high secrecy rates can be obtained only with power and coding rate
adaptation. Moreover, we highlight the importance of optimally dividing the
transmission power in the frequency domain, and note that the optimal scheme
provides high gains in secrecy rate over the uniform power splitting case.
Analytically, we explain how to find the optimal policy and prove some of its
properties. In our numerical evaluation, we discuss how the maximum achievable
secrecy rate changes according to the various system parameters. Furthermore,
we discuss the effects of a finite battery on the system performance and note
that, in order to achieve high secrecy rates, it is not necessary to use very
large batteries.Comment: Accepted for publication in IEEE Journal on Selected Areas in
Communications (Mar. 2016
Stochastic Optimization of Energy Harvesting Wireless Communication Networks
Energy harvesting from environmental energy sources (e.g., sunlight) or from man-made
sources (e.g., RF energy) has been a game-changing paradigm, which enabled the possibility
of making the devices in the Internet of Things or wireless sensor networks operate
autonomously and with high performance for years or even decades without human
intervention. However, an energy harvesting system must be correctly designed to achieve
such a goal and therefore the energy management problem has arisen and become a critical
aspect to consider in modern wireless networks. In particular, in addition to the hardware
(e.g., in terms of circuitry design) and application point of views (e.g., sensor deployment),
also the communication protocol perspective must be explicitly taken into account; indeed,
the use of the wireless communication interface may play a dominant role in the energy
consumption of the devices, and thus must be correctly designed and optimized. This
analysis represents the focus of this thesis.
Energy harvesting for wireless system has been a very active research topic in the past
decade. However, there are still many aspects that have been neglected or not completely
analyzed in the literature so far. Our goal is to address and solve some of these new
problems using a common stochastic optimization setup based on dynamic programming.
In particular, we formulate both the centralized and decentralized optimization problems
in an energy harvesting network with multiple devices, and discuss the interrelations
between these two schemes; we study the combination of environmental energy harvesting
and wireless energy transfer to improve the transmission rate of the network and achieve a
balanced situation; we investigate the long-term optimization problem in wireless powered
communication networks, in which the receiver supplies wireless energy to the terminal
nodes; we deal with the energy storage inefficiencies of the energy harvesting devices,
and show that traditional policies may be strongly suboptimal in this context; finally, we
investigate how it is possible to increase secrecy in a wireless link where a third malicious
party eavesdrops the information transmitted by an energy harvesting node