Incremental Diversity: A Framework for Rate-Adaptation/Energy-Conservation Enhancement in MIMO Systems

In recent years, MIMO technology has emerged as one of the technical breakthroughs in the field of wireless communications. Two famous MIMO techniques have become investigated thoroughly throughout the literature;Spatial Multiplexing, and Space Time Block Coding. On one hand, Spatial Multiplexing offers high data rates. On the other hand, Space Time Block Coding presents transmission fidelity. This imposes a fundamental tradeoff between capacity and reliability. Adaptive MIMO Switching schemes have been proposed to select the MIMO scheme that best fits the channel conditions. However, the switching schemes presented in the literature directly switch between the MIMO endpoints. In this paper, an adaptive MIMO system that incrementally switches from multiplexing towards diversity is proposed. The proposed scheme is referred to as incremental diversity and can be set to operate in two different modes;Rate-Adaptive, and Energy-Conservative Incremental Diversity. Results indicate that the proposed incremental diversity framework achieves transmission reliability offered by MIMO diversity, while maintaining a gradual increase in spectral efficiency (in the Rate-Adaptive mode) or a reduction in required number of received symbols (in the Energy-Conservative mode) with increase in the SNR.

Superconvergence of Energy-Conserving Discontinuous Galerkin Methods for Linear Hyperbolic Equations

In this paper,we study the superconvergence properties of the energy-conserving discontinuous Galerkin(DG)method in[18]for one-dimensional linear hyperbolic equations.We prove the approximate solution superconverges to a particular projection of the exact solution.The order of this superconvergence is proved to be k+2 when piecewise Pk polynomials with K≥1 are used.The proof is valid for arbitrary non-uniform regular meshes and for piecewise polynomials with arbitrary K≥1.Furthermore,we find that the derivative and function value approxi?mations of the DG solution are superconvergent at a class of special points,with an order of k+1 and R+2,respectively.We also prove,under suitable choice of initial discretization,a(2k+l)-th order superconvergence rate of the DG solution for the numerical fluxes and the cell averages.Numerical experiments are given to demonstrate these theoretical results.

Energy-Conserving Transmission Network Model Based on Service-Awareness

In this paper, we propose a service-aware network model which is based on the traffic pattern in data center. First of all, we analyze the traffic model in data center networks. Then we use this model to make the net topology integration and classification through the software define network. In order to achieve the purpose of energy consumption optimization, we divide the hosts into same VLAN according to their interaction frequency to reduce the cross VLAN transmission consumption. Simulation results show that we get a great energy improvement in the fat tree net topology.

ARBITRARILY HIGH-ORDER ENERGY-CONSERVING METHODS FOR HAMILTONIAN PROBLEMS WITH QUADRATIC HOLONOMIC CONSTRAINTS

In this paper,we define arbitrarily high-order energy-conserving methods for Hamilto-nian systems with quadratic holonomic constraints.The derivation of the methods is made within the so-called line integral framework.Numerical tests to illustrate the theoretical findings are presented.

Energy Conservation Strategy for Big News Data on HDFS

In this paper,an energy-conservation Hadoop Distributed File System(HDFS)oriented to massive news data is proposed based on news access pattern,in order to reduce energy consumption of big news data storage system.First,divide all data nodes into real-time responding hot data nodes and standby cold data nodes.To make a good balance between data access performance and energyconservation,this paper takes two strategies of priority allocation,named Active State Node Priority(ASNP)and Lower Than Average Utilization Rate Node Priority(LANP),to mostly guarantee the balance of data distribution in cluster in order to obtain a good data access performance.It also confirms the opportunities to move data from hot data nodes to cold data nodes is based on the access pattern of news data and develops a simulating experimental platform that can evaluate energy consumption of any file accessing operation under any different storage strategies and parameters.Simulation experiments shows that strategies proposed in this paper saves 20%–35%energy than traditional HDFS and 99.9%responding time of reading files will not be affected,with an average of 0.008%–0.036%time delay.

New Energy-Conserved Identities and Super-Convergence of the Symmetric EC-S-FDTD Scheme for Maxwell’s Equations in 2D

The symmetric energy-conserved splitting FDTD scheme developed in[1]is a very new and efficient scheme for computing theMaxwell’s equations.It is based on splitting the whole Maxwell’s equations and matching the x-direction and y-direction electric fields associated to the magnetic field symmetrically.In this paper,we make further study on the scheme for the 2D Maxwell’s equations with the PEC boundary condition.Two new energy-conserved identities of the symmetric EC-S-FDTD scheme in the discrete H^(1)-norm are derived.It is then proved that the scheme is unconditionally stable in the discrete H^(1)-norm.By the new energy-conserved identities,the super-convergence of the symmetric EC-S-FDTD scheme is further proved that it is of second order convergence in both time and space steps in the discrete H^(1)-norm.Numerical experiments are carried out and confirm our theoretical results.

Symmetric Energy-Conserved Splitting FDTD Scheme for the Maxwell’s Equations

In this paper,a new symmetric energy-conserved splitting FDTD scheme(symmetric EC-S-FDTD)for Maxwell’s equations is proposed.The new algorithm inherits the same properties of our previous EC-S-FDTDI and EC-S-FDTDII algorithms:energy-conservation,unconditional stability and computational efficiency.It keeps the same computational complexity as the EC-S-FDTDI scheme and is of second-order accuracy in both time and space as the EC-S-FDTDII scheme.The convergence and error estimate of the symmetric EC-S-FDTD scheme are proved rigorously by the energy method and are confirmed by numerical experiments.

Multisymplectic five-point scheme for the nonlinear wave equation

In this paper, we introduce the multisymplecticstructure of the nonlinear wave equation, and prove that theclassical five-point scheme for the equation is multisymplec-tic. Numerical simulations of this multisymplectic scheme onhighly oscillatory waves of the nonlinear Klein-Gordonequation and the collisions between kink and anti-kink soli-tons of the sine-Gordon equation are also provided. The mul-tisymplectic schemes do not need to discrete PDEs in thespace first as the symplectic schemes do and preserve notonly the geometric structure of the PDEs accurately, but alsotheir first integrals approximately such as the energy, themomentum and so on. Thus the multisymplectic schemeshave better numerical stability and long-time numerical be-havior than the energy-conserving scheme and the symplec-tic scheme.