Earticle

An ideal routing strategy shall be able to help the delay tolerant network (DTN) achieve an optimal transmission performance under the premise of lower energy consumption. However, due to the diverse of the application scenarios, it is hard to use one or more types of routing strategies as a universal optimum solution. There is a need to establish a routing strategy model of the corresponding DTN network for different application scenarios, analyze and evaluate the strategy model in combination of the knowledge of the operational research and statistics. For a complex data transmission DTN network scenario, with the introducing of a line programming method, the big-data and multi-node network transmission problem can be abstracted to a large-scale line programming problem. In this paper, the feasibility of solving the large-scale line programming problem by the column generation algorithm has been analyzed, and a column generation algorithm-based DTN routing strategy under the complex data transmission scenario has been designed. This routing strategy can realize the quantization of the routing strategy performance by the column generation algorithm. Also, by the simulation experiments, the performance of complex data transmission DTN routing strategy under different factors has been analyzed, and the performance of the column generation algorithm-based DTN routing strategy has been compared with the performance of the traditional jet waiting routing strategy

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.

Low cost and low power is one of the important reasons in the wide application of backscatter sensor networks. Based on LabVIEW and USRP platforms, this paper presents and implements a simple and configurable SDR prototype for backscatter sensor networks. The SDR prototype can apply to the multi-sensor environment with low power. The prototype consists of configurable backscatter transceiver with homodyne receiver and sensor nodes. It can reduce the power consumption of system efficiently through harvesting wireless RF energy and waking sensor nodes. The frequency division multiple access method with configurable sub-carrier is proposed, and the constraint conditions of sensing data pulse period for avoiding collision among sensors are presented and proved in this paper. The performance of the prototype is analyzed, and the closed-form solution of the probability of outage under the log-normal channel is also given and proved. Finally, the experiment and simulation show the SDR prototype is effective and feasible. The EVM value is less than 2.8%, and the probability of outage error between numerical analysis and Monte Carlo simulation is less than 1.86%.

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.

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.

Against the backdrop of Internet of Things on campus, this paper makes Internet of things cover the entire campus through wired and wireless accesses. As a result, campus sees the fulfillment of information transfer via computers, mobile phones, devices and other articles, which is the embodiment of intelligence. Besides, OPNET is used for modeling and simulation of wireless network structure in SDN intelligent campus, with a view to analyzing the feasibility and advantages of various campus network topologies. Then, a reasonable scheme is presented responding to different types of topologies, which is conducive to better building an intelligent campus.

Satellite systems are a perfect alternative system to cover wide areas on the earth, especially oceans and desert areas, and to provide broadband communications to all aircraft. Low earth orbit (LEO) satellite constellations are important in future air traffic control (ATC) communication networks due to their advantages, such as whole global coverage and low propagation time. However, the satellites are not stationary; a contact between aircraft and satellite may be subjected to handovers. Many techniques have been proposed in order to deal with the cell handover issue. In this paper, the Handover procedure implication in the communication blocking probability is estimated via simulation. To reduce the high number of Handovers, some strategies are used to cope with. Simulation models have been developed to improve all the features evaluated in this paper.