Earticle

A statistical analysis has been made on 969 two-syllabic words in Uyghur Acoustical Database. The major part of this paper concentrates on the basic acoustic features of two-syllabic harmonious words including formant frequency, resonance peak value, vowel duration, vowel pitch and the sound intensity. And we have summarized certain rules and conclusions of great importance for adjusting vowel harmony in parametric speech synthesis or waveform concatenated speech synthesis system.

Self-localization is a fundamental problem in mobile robotics. It consists of estimating the position of a robot given a map of the environment and information obtained by sensors. Among the algorithms used to address this issue, the Monte Carlo technique has obtained a considerable attention by the scientific community due to its simplicity and efficiency. Monte Carlo localization is a sample-based technique that estimates robot´s pose using a probability density function represented by samples (particles). The complexity of this algorithm scales proportionally to the number of particles used. The larger the environment, the more particles are required for robot localization. This fact limits the use of this algorithm in large size environments. In order to improve the efficiency of the Monte Carlo technique and allow it to be used in large environments we propose a parallel implementation of it. Our implementation is based on OpenMP and MPI message passing interface. Experimental results are used to show the efficiency of our approach.

This paper derives the analytical expression of the temporal autocorrelation function (ACF) of the non-stationary three dimensional (3D) multipath scattering channels, in which scatterers move with constant velocities in random directions around transceivers. The analytical expression involves high dimensional integration within finite interval, thus a methodology based on ray-tracing is proposed to carry out its numerical solution. The analytical expression and the corresponding ray-tracing based model serve as the canonical forms for the correlation analysis of non-stationary 3D multipath scattering channels, which include two special cases: two dimensional (2D) multipath scattering and stationary multipath scattering. Numerical results show that: in case of non-stationary 3D multipath scattering, with the increase of the velocity and the density of scatterers, the temporal ACF would attenuate more rapidly. These results would allow engineers more appropriate determination on coherence time and coherence bandwidth for vehicle-to-vehicle communication systems.

In this paper, we propose a local adaptive transmission power control method to improve the network connectivity and energy efficiency etc. for wireless sensor networks. Path loss exponent and energy control coefficient are studied carefully to show the minimum cover district of each node more accurately based on network environment and the application scenarios. Our proposed local adaptive power control method can also provide self-healing function which makes the network maintain the best performance for a long time when a few nodes exhaust their energy or a fresh batch of nodes are deployed. Simulation results show that our proposed method is very effective in establishing a good logical network structure and prolonging the network lifetime.

A trust and reputation management framework for VANETs (Vehicular Ad Hoc Networks) is proposed. In the framework, a similarity mining technique is used for identifying similar messages or similar vehicles. And a reputation evaluation algorithm is proposed for evaluating a new vehicle’s reputation based on the similarity theory. Similarities from different recommenders are used as weights for computing a vehicle’s recommendation based reputation. An updating algorithm for reputations is proposed in the framework. The framework is applied to decide whether a message is trustworthy when a vehicle receives an event message.

Nowadays, Dense Wavelength Division Multiplexing (DWDM) has become a key component of the world’s communications infrastructure. The significant improvement in high-speed electronics and optical components, and multi-level modulation formants and coherent receiver technology has enabled high rate data transmission. DWDM promises to increase the bandwidth per fiber as the bit rate and the number of wavelengths increase. According to ITU-T G.694.1, mostly used DWDM systems have been operating with 40, 80 and 120 wavelengths, and with advanced modulation schemes and coherent receiver technology along better dispersion management, a single wavelength in today’s world can able to transmit upto 100Gbps; thus total maximum bandwidth is an amazing 4Tbps, 8Tbps, and 12Tbps, respectively. However, today’s commercial systems have a fiber transmission requirement for around 10Tbps, and globally demand has been increasing about 35% to 45% per year. Hence, to meet this increasing demand transponders transmission rate must have to be increased. This paper reviews the progress and techniques used to increase wavelength throughput from 2.5Gbps to 100Gbps, and investigates the challenges to transmit data beyond 100Gbps in a single operational cycle.

The frequency hopping technology is widely used in wireless sensor networks with the security becomes more and more important. Channel evaluation is important for adaptive frequency hopping system and we proposed a scheme of optimal channel selection with channel evaluation, which can get an accurate and comprehensive channel evaluation by analyzing the Signal-To-Noise Ratio (SNR), loss rate and delay.

The routing protocol transport the best connection, creating during message in the network. The router can work with the help of routing protocols. The various routing protocols can be present, but the most famous routing protocols are Routing Information protocol (RIP) and the Open Shortest Path First (OSPF). Smart Open Shortest Path First (S-OSPF), which offers the extended representations for conventional OSPF gives less congestion ratio by allocating traffic. Multicast Open Shortest Path First (MOSPF), it offers the facility to forward multicast datagram from one network to another. In this paper, we are defining the two protocols and the related worked on them. In this each link provides the autonomous system to create the shortest path to makes and creates the destination tables. Both logical and hardware address play the important roles, responsible for getting packet and forward through a correct destination host.

Cognitive Radio (CR) is a novel technology that can improve the utilization efficiency of the radio spectrum and also address the spectrum scarcity problem by opportunistically using the unused channels (spectrum holes / white spaces) in the Licensed Spectrum of Primary Users. Spectrum sensing is the primary function of CR which determines the spectrum holes for opportunistic usage by Secondary Users. Spectrum sensing plays a critical role in Cognitive Radio. The development of a reliable and accurate spectrum sensing is very essential to propound quick and accurate detection of white spaces for better throughput of Secondary User network under the constraint of the specified Primary System protection. In this paper, a Cooperative Spectrum Sensing using Wavelet Denoising along with Soften Hard Decision technique has been proposed to improve the performance of spectrum sensing. Simulation result shows an improvement of nearly 15% in the Probability of Missed Detection for a target Probability of False Alarm of 0.1 and SNR of -10 dB. Also 50% improvement in error probability has been achieved with 1-D one level wavelet denoising.