43157650
Error Probability of OFDM Systems Impaired by Carrier Frequency Offset in Frequency Selective Rayleigh Fading Channels
Orthogonal frequency division multiplexing (OFDM) is sensitive to carrier frequency offset (CFO), which destroys the orthogonality and causes inter-carrier interference (ICI). In this paper, we investigate the average error probability of OFDM systems impaired by CFO over frequency selective Rayleigh fading channels. By exploiting the Beaulieu series, the effects of CFO on the symbol error rate (SER) and bit error rate (BER) performance, which depend strongly on the statistical characteristics of the fading channels, are expressed as the sum of an infinite series in terms of the characteristic function (CHF) of the ICI. We only consider OFDM systems modulated with BPSK, QPSK, 8-PSK and 16-QAM, and the Gray-coded mapping are employed for the evaluation of BER performance.
30164221
Limited feedback design for MIMO broadcast channels with ARQ mechanism
We investigate the design of a limited feedback mechanism for multiple-input-multiple-output (MIMO) broadcast systems that are equipped with automatic repeat request (ARQ) capabilities. Given multiple antennas at the base-station (BS) and single antenna subscribers, we focus on maximizing the ergodic system sum capacity and propose an adaptive feedback bit allocation scheme under the constraint of total feedback bandwidth. Furthermore, we develop two efficient feedback allocation schemes based on asymptotic analysis. We present simulation results that verify the effectiveness of the proposed adaptive allocation schemes.
24579136
The Periodic Solution of a Class of Two Neurons Hopfield Network with Distributed Delay
This paper considers the two neurons Hopfield network with distributed delay, which can be transformed into the three-dimensional differential system. Then we use the result of competitive system to get the periodic solution of the system. We also show that existence and uniqueness of equilibrium point, and if the equilibrium is unstable, then an orbitally asymptotically stable periodic solution exists.
35283967
Detection function method and its application to a class of quintic Hamiltonian systems with quintic perturbations
By using the bifurcation theory of planar dynamical systems and the method of detection functions to investigate the bifurcation of limit cycles of a perturbed quintic Hamiltonian system. It is shown that under two different sets of controlled parameters, the given system has at least 23 limit cycles having two different configurations of the compound eyes, respectively.
13125864
Bifurcations of limit cycles for a perturbed quintic Hamiltonian system with four infinite singular points
By using the theory of bifurcations of dynamical systems and the method of detection function to investigate the bifurcation of limit cycles of a perturbed quintic Hamiltonian system with 25 finite singular points and four infinite singular points. From the detection functions for the perturbed system, we prove that under different determined parameter condition, the given system has at least 22 and 20 limit cycles and the configurations of compound eyes are also obtained.
19005326
A hybrid particle swarm optimization approach with prior crossover differential evolution
Particle swarm optimization (PSO) is population-based heuristic searching algorithm. PSO has excellent ability of global optimization. However, there are some shortcomings of prematurity, low convergence accuracy and speed, similarly to other evolutionary algorithms (EA). To improve its performance, a hybrid particle swarm optimization is proposed in the paper. Firstly, the average position and velocity of particles are incorporated into basic PSO for concerning with the effect of the evolution of the whole swarm. Then a differential evolution (DE) computation, which introduces an extra population for prior crossover, is hybridized with the improved PSO to form a novel optimization algorithm, PSOPDE. The role of prior crossover is to appropriately diversify the population and increase the probability of reaching better solutions. DE component takes into account the stochastic differential variation, and enhances the exploitation in the neighborhoods of current solutions. PSOPDE is implemented on five typical benchmark functions, and compared with six other algorithms. The results indicate that PSOPDE behaves better, and greatly improve the searching efficiency and quality.
41941441
Analysis of chaotic behavior in the extended Duffing-Van der Pol system subject to additive non-symmetry biharmonical excitation
Abstract The problem of controlling chaos for a certain class of extended Duffing–Van der Pol system under additive non-symmetry biharmonical excitation with specific parameters is investigated by the way of random phase parallel movement in this paper. The results show that the initial phase has some important effect on controlling chaos and noises can increase the robustness of controlling chaos. With specific parameters, the adjustment phase of the first harmonical excitation and the noise intensity of the second non-symmetry harmonical excitation do not suppress chaos in the system. In order to control chaos, the diagrams of phase versus amplitude of the second harmonical excitation were drawn on the basis of the fact that chaos can be suppressed when the sign of the top Lyapunov exponent is negative. The robustness and mechanism of suppressing chaotic motion with random phase or noise were also initially discussed. The author put forward a method called random phase parallel movement to control chaos. The availability of this method was validated via the curve of the top Lyapunov exponent, phase diagram, Poincare surface of the section and time evolution.