754 research outputs found
The childhood development initiative: developing quality services
The Childhood Development Initiative (CDI) has created a ten-year strategy to improve the health, safety and learning of the children of Tallaght West, and to strengthen their sense of belonging in their own communities. This paper portrays an overview of the strategy, the principles of freedom and prevention which underpin the project and outlines two of the eight activities, namely the Early Childhood Care and Education (ECCE) programme and the Enhancing Quality through Integration and Training (EQIT) programme. These two activities seek to develop high quality services in accordance with international evidence on early childhood development, local quantitative and qualitative research, national policy developments and scientific service design and will be rigorously evaluated. We will argue that given the process adopted and positive evaluation results, these services should be replicated and mainstreamed
Downlink Power Control in User-Centric and Cell-Free Massive MIMO Wireless Networks
Recently, the so-called cell-free Massive MIMO architecture has been
introduced, wherein a very large number of distributed access points (APs)
simultaneously and jointly serve a much smaller number of mobile stations
(MSs). A variant of the cell-free technique is the user-centric approach,
wherein each AP just decodes the MSs that it receives with the largest power.
This paper considers both the cell-free and user-centric approaches, and, using
an interplay of sequential optimization and alternating optimization, derives
downlink power-control algorithms aimed at maximizing either the minimum users'
SINR (to ensure fairness), or the system sum-rate. Numerical results show the
effectiveness of the proposed algorithms, as well as that the user-centric
approach generally outperforms the CF one.Comment: presented at the 28th Annual IEEE International Symposium on
Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2017), Montreal
(CA), October 201
Energy-Efficient Downlink Power Control in mmWave Cell-Free and User-Centric Massive MIMO
This paper considers cell-free and user-centric approaches for coverage
improvement in wireless cellular systems operating at millimeter wave
frequencies, and proposes downlink power control algorithms aimed at maximizing
the global energy efficiency. To tackle the non-convexity of the problems, an
interaction between sequential and alternating optimization is considered. The
use of hybrid analog/digital beamformers is also taken into account. The
numerical results show the benefits obtained from the power control algorithm,
as well as that the user-centric approach generally outperforms the cell-free
one.Comment: 4 pages; to be presented at the IEEE 5G Worls Forum Conference, Santa
Clara, July 2018. arXiv admin note: text overlap with arXiv:1710.0781
Energy Efficiency in MIMO Underlay and Overlay Device-to-Device Communications and Cognitive Radio Systems
This paper addresses the problem of resource allocation for systems in which
a primary and a secondary link share the available spectrum by an underlay or
overlay approach. After observing that such a scenario models both cognitive
radio and D2D communications, we formulate the problem as the maximization of
the secondary energy efficiency subject to a minimum rate requirement for the
primary user. This leads to challenging non-convex, fractional problems. In the
underlay scenario, we obtain the global solution by means of a suitable
reformulation. In the overlay scenario, two algorithms are proposed. The first
one yields a resource allocation fulfilling the first-order optimality
conditions of the resource allocation problem, by solving a sequence of easier
fractional problems. The second one enjoys a weaker optimality claim, but an
even lower computational complexity. Numerical results demonstrate the merits
of the proposed algorithms both in terms of energy-efficient performance and
complexity, also showing that the two proposed algorithms for the overlay
scenario perform very similarly, despite the different complexity.Comment: to appear in IEEE Transactions on Signal Processin
Resource Allocation for Energy-Efficient 3-Way Relay Channels
Throughput and energy efficiency in 3-way relay channels are studied in this
paper. Unlike previous contributions, we consider a circular message exchange.
First, an outer bound and achievable sum rate expressions for different
relaying protocols are derived for 3-way relay channels. The sum capacity is
characterized for certain SNR regimes. Next, leveraging the derived achievable
sum rate expressions, cooperative and competitive maximization of the energy
efficiency are considered. For the cooperative case, both low-complexity and
globally optimal algorithms for joint power allocation at the users and at the
relay are designed so as to maximize the system global energy efficiency. For
the competitive case, a game theoretic approach is taken, and it is shown that
the best response dynamics is guaranteed to converge to a Nash equilibrium. A
power consumption model for mmWave board-to-board communications is developed,
and numerical results are provided to corroborate and provide insight on the
theoretical findings.Comment: Submitted to IEEE Transactions on Wireless Communication
Globally Optimal Energy-Efficient Power Control and Receiver Design in Wireless Networks
The characterization of the global maximum of energy efficiency (EE) problems
in wireless networks is a challenging problem due to the non-convex nature of
investigated problems in interference channels. The aim of this work is to
develop a new and general framework to achieve globally optimal solutions.
First, the hidden monotonic structure of the most common EE maximization
problems is exploited jointly with fractional programming theory to obtain
globally optimal solutions with exponential complexity in the number of network
links. To overcome this issue, we also propose a framework to compute
suboptimal power control strategies characterized by affordable complexity.
This is achieved by merging fractional programming and sequential optimization.
The proposed monotonic framework is used to shed light on the ultimate
performance of wireless networks in terms of EE and also to benchmark the
performance of the lower-complexity framework based on sequential programming.
Numerical evidence is provided to show that the sequential fractional
programming framework achieves global optimality in several practical
communication scenarios.Comment: Accepted for publication in the IEEE Transactions on Signal
Processin
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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