1,533 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
Maximizing Energy-Efficiency in Multi-Relay OFDMA Cellular Networks
This contribution presents a method of obtaining the optimal power and
subcarrier allocations that maximize the energy-efficiency (EE) of a
multi-user, multi-relay, orthogonal frequency division multiple access (OFDMA)
cellular network. Initially, the objective function (OF) is formulated as the
ratio of the spectral-efficiency (SE) over the power consumption of the
network. This OF is shown to be quasi-concave, thus Dinkelbach's method can be
employed for solving it as a series of parameterized concave problems. We
characterize the performance of the aforementioned method by comparing the
optimal solutions obtained to those found using an exhaustive search.
Additionally, we explore the relationship between the achievable SE and EE in
the cellular network upon increasing the number of active users. In general,
increasing the number of users supported by the system benefits both the SE and
EE, and higher SE values may be obtained at the cost of EE, when an increased
power may be allocated.Comment: 6 pages, 5 figures, 1 table, to appear in Proc. IEEE 2013 56th Global
Communications Conference (GLOBECOM 2013), Atlanta, USA, December, 201
Energy-Efficient Scheduling and Power Allocation in Downlink OFDMA Networks with Base Station Coordination
This paper addresses the problem of energy-efficient resource allocation in
the downlink of a cellular OFDMA system. Three definitions of the energy
efficiency are considered for system design, accounting for both the radiated
and the circuit power. User scheduling and power allocation are optimized
across a cluster of coordinated base stations with a constraint on the maximum
transmit power (either per subcarrier or per base station). The asymptotic
noise-limited regime is discussed as a special case. %The performance of both
an isolated and a non-isolated cluster of coordinated base stations is examined
in the numerical experiments. Results show that the maximization of the energy
efficiency is approximately equivalent to the maximization of the spectral
efficiency for small values of the maximum transmit power, while there is a
wide range of values of the maximum transmit power for which a moderate
reduction of the data rate provides a large saving in terms of dissipated
energy. Also, the performance gap among the considered resource allocation
strategies reduces as the out-of-cluster interference increases.Comment: to appear on IEEE Transactions on Wireless Communication
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