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981.
The demand to reduce energy consumption in wireless networks has become popular recently. In this paper, aimed at the problem that how to reduce energy consumption through on-off control in wireless networks without losing system performance significantly, we present our solution both in a single base station and the multi-base station scenario. Under the assumption that the network arrival and departure process are Markov, we first model and solve the problem of optimal on-off control in single base station scenario using dynamic integer programming (DIP) method, then we extend the optimal solution to multi-base station scenario and raise an effective heuristic method in two layer networks, the trade-off between QoS level and energy consumption has been given according to our analysis and simulation. Numerical results are provided to demonstrate that the proposed method offer significant gain in terms of the energy efficiency.  相似文献   
982.
983.
In this paper, the outage probability (OP) performance of multiple-relay-based incremental amplify-and-forward relaying device-to-device networks with transmit antenna selection (TAS) over N-Nakagami fading channels is investigated. The exact closed-form expressions for OP of the optimal and suboptimal TAS schemes are derived. The power allocation problem is formulated for performance optimization. Then the OP performance under different conditions is evaluated through numerical simulations to verify the analysis. The simulation results showed that optimal TAS scheme has a better OP performance than suboptimal TAS scheme, but the performance gap between the optimal and suboptimal schemes diminishes by increasing the number of antennas at the source; the fading coefficient, the number of cascaded components, the relative geometrical gain, the number of antennas, and the power-allocation parameter have an important influence on the OP performance.  相似文献   
984.
This paper presents an arterial green-wave synchronous coordination model for bus and non-bus lanes based on platoon dispersion theory. As the traffic light at an upstream intersection change from red to green, the dispersive characteristics of these vehicles moving from upstream to the downstream were analyzed by assuming velocities of two platoon following a normal distribution pattern. The model aims at analyzing relationship between traffic flow, distance between adjacent intersections, and signaling time in order to achieve arterial green-wave synchronous coordination in both the bus and non-bus lanes. To facilitate coordination in a traffic signal control system, the number of vehicles forced to stop at the head of the platoon as well as the number of vehicles trapped at the tail of the platoon were determined and presented in a tabular form for use in the proposed traffic light coordination model. Finally, a numeric computation for the coordination of successive signals is presented to illustrate the validity of the proposed model.  相似文献   
985.
986.
There exist several applications of wireless sensor networks in which the reliable operation can be crucial. Fault prediction is a critical problem in reliability theory for ribbon wireless sensor networks (RWSNs). Accurate fault prediction can effectively improve the availability of the WSNs system. In this paper, we evaluated the network performance for RWSNs, studied the basic theory of kernel functions, proposed a new failure prediction method based on kernel function, and selected the radial basis function as kernel function failure prediction models from two aspects of node hardware failures and network failures for fault prediction. Theoretical evidence and experimental results have shown that the proposed algorithmic prediction method has higher accuracy of 12 and 15% than that of GRNN and PNN respectively. Finally, we provided extensive numerical results to demonstrate the usage and efficiency of the proposed algorithms and complement our theoretical analysis.  相似文献   
987.
In this paper a new power efficient routing algorithm for MANETs with self-organizing and self-routing features is described and its performance analyzed in different simulation scenarios. The algorithm has the logic of a non-cooperative routing algorithm based on the evaluation of a weight parameter, the latter being a function of properties of the MANET nodes related to the nominal available power and the transmission range. A self-estimation of this weight parameter for each node is introduced in the routing process based on the status and functional history of the node. The routing is based on network layering, formation of service areas in each layer and choice of nodes from these areas to have the functionality of default gateways. The proposed algorithm, named service zone gateway prediction (SZGP), is a hybrid type of routing mechanism, incorporating pre-computed multipath hop-by-hop distributed routing, with a periodically updated hierarchical multilayered structure. The results from the simulation experiments show that the performance of the proposed SZGP algorithm in relation to the basic performance parameters such as packet delivery ratio, delay and throughput are similar to those of the well-known AODV algorithm, but in relation to power efficiency the proposed algorithm outperforms AODV significantly. This is due to the fact that such an approach reduces the overall number of broadcasts in the network and ensures a reliable and energy efficient connection by balancing the load among the nodes.  相似文献   
988.
The Internet of Things (IoT) is the communications paradigm that can provide the potential of ultimate communication. The IoT paradigm describes communication not only human to human (H2H) but also machine to machine (M2M) without the need of human interference. In this paper, we examine, review and present the current IoT technologies starting from the physical layer to the application and data layer. Additionally, we focus on future IoT key enabling technologies like the new fifth generation (5G) networks and Semantic Web. Finally, we present main IoT application domains like smart cities, transportation, logistics, and healthcare.  相似文献   
989.
Glass with compositions xK2O-(30 ? x)Li2O-10WO3-60B2O3 for 0 ≤ x ≤ 30 mol.% have been prepared using the normal melt quenching technique. The optical reflection and absorption spectra were recorded at room temperature in the wavelength range 300–800 nm. From the absorption edge studies, the values of the optical band gap (E opt) and Urbach energy (ΔE) have been evaluated. The values of E opt and ΔE vary non-linearly with composition parameter, showing the mixed alkali effect. The dispersion of the refractive index is discussed in terms of the single oscillator Wemple Di-Domenico model.  相似文献   
990.
Image registration (IR) aims to map one image to another of a same scene. With rapid progress in image acquisition technologies, 3D IR becomes an important problem in magnetic resonance imaging (MRI) and other applications. In the literature, however, most IR methods are for 2D images and there are only a limited number of 3D methods available. Because 3D images have much complicated structure than their 2D counterparts, 3D IR is not just a simple generalization of the 2D IR problem. In this paper, we develop a 3D IR method that can handle cases with affine geometric transformations well. By its definition, an affine transformation maps a line to a line, and it includes rotation, translation, and scaling as special cases. In practice, most geometric transformations involved in IR problems are affine transformations. Therefore, our proposed method can find many IR applications. It is shown that this method works well in various cases, including cases when the data size of a 3D image is reduced for different reasons. This latter property makes it attractive for many 3D IR applications, since 3D images are often big in data size and it is natural to reduce their size for fast computation.  相似文献   
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