The mobile communication systems services are shifting from voice conversation to data transmission through the Internet. The information transferred over the Internet is becoming increasingly rich, there will be a de...
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The mobile communication systems services are shifting from voice conversation to data transmission through the Internet. The information transferred over the Internet is becoming increasingly rich, there will be a demand of peak data transmission rates of around 100 Mbps-1Gbps even in mobile communications systems. However, as the data transmission rate becomes higher, the peak transmit power becomes larger. To decrease the peak transmit power, a multi-hop virtual cellular network (VCN) that can significantly reduce the transmit power was proposed. This paper introduces the multi-hop maximal ratio combining (MHMRC), to the VCN in order to decrease the route total transmit power, improve the transmit power efficiency degradation caused by the carrier frequency difference between the control and the data communication channels for VCN. It was shown that the MHMRC diversity gain decreases. MHMRC diversity can reduce the number of hops in the rout.
Wireless networked control system (WINCS), based on distributed control systems of wireless network, integrate control technology, computer technology, network technology and communication technology. The delay of con...
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Wireless networked control system (WINCS), based on distributed control systems of wireless network, integrate control technology, computer technology, network technology and communication technology. The delay of controlled plant and wireless network transmission may have bad impacts on system performance. Aiming at solving the delay problem, this paper analyzes the existing problems of wireless network and the solutions for WINCS firstly. Then, the components of simulation software true time toolbox and the function of each module are detailed. Thirdly, a wireless networked control system is constructed on true time simulation platform, of which controlled plant is a DC servo and wireless transmission network is ZigBee protocol. Performances of control system are compared under conventional PID and predictive PI algorithms, which show that predictive PI controller can obtain better control effects in a large time-delay system. Finally, this paper analyzes the composition of the system delays, including the sensor to the controller delay and the controller to the actuator delay, and outlines the conclusions.
This paper describes an model of VoIP traffic capacity estimation of hybrid network based on FUTR(finite user timely model), it figures out the key factors that affect the upper limit of VoIP traffic capacity and pres...
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This paper describes an model of VoIP traffic capacity estimation of hybrid network based on FUTR(finite user timely model), it figures out the key factors that affect the upper limit of VoIP traffic capacity and presents different traffic capacity estimation models and approaches based on different traffic characteristics of PSTN and softswitch. The models and approaches are validated in real network.
In this paper, an empirical analysis of energy conservation for wireless sensor networks has been reported. An energy computation technique has been proposed for energy measurement in sensor networks. CSMA/CA with RTS...
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In this paper, an empirical analysis of energy conservation for wireless sensor networks has been reported. An energy computation technique has been proposed for energy measurement in sensor networks. CSMA/CA with RTS/CTS and overhearing avoidance has been implemented in the PICSENSE nodes and the energy consumption of the two Medium Access control Protocols has been reported. Processor duty cycling is also implemented in PICSENSE nodes to conserve the energy.
Swarm intelligence (SI) is emerged with collective intelligence of groups of simple agents. SI offers an alternative way of designing intelligent system, in which autonomy, emergence and distributed functioning replac...
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Swarm intelligence (SI) is emerged with collective intelligence of groups of simple agents. SI offers an alternative way of designing intelligent system, in which autonomy, emergence and distributed functioning replaces control, preprogramming and centralization systems. This approach emphasizes on distributed, flexibility, robustness and direct or indirect communication among relatively simple agents. A new class of algorithms, inspired by swarm intelligence, is currently being developed that can solve numerous problems of modern communications networks. These algorithms rely on the interaction of a multitude of simultaneously interacting agents. They are Ant Based control algorithm, Antnet algorithm, Ant Colony Based Routing Algorithm, Mobile Ant Based Routing, Termite. They differ based on the applications used. A survey of such algorithms is presented here.
This article expounds space tracking's working theory its constructure, space object photoelectric detecting technology's characters, analyses the analytics formula of photoelectric position sensitive detector...
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This article expounds space tracking's working theory its constructure, space object photoelectric detecting technology's characters, analyses the analytics formula of photoelectric position sensitive detector under the absolute reversal of biasing and weak signal circumstances and the tracking error signal's distilling method, the key technological questions in space tracking, it gives space capturing N tracking processing system's adopting tracking methods in carrying all-field capturing and tracking.
This paper is an evaluation of four information theoretic image fusion quality assessment metrics and how they perform, in comparison with some of the existing quantitative metrics. The information theoretic fusion me...
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This paper is an evaluation of four information theoretic image fusion quality assessment metrics and how they perform, in comparison with some of the existing quantitative metrics. The information theoretic fusion metrics evaluated are: Fusion Factor (FF), Fusion Symmetry (FS), Image Fusion Performance Measure (IFPM) and Renyi Entropy (RE). Even though traditional quality assessment metrics like Mean Square Error (MSE), Correlation Coefficient (CC) etc, are being improved by incorporating the edge information, similarity measure between the images, taking the luminance and contrast measures in the images etc, most of the quantitative approaches still don't give a satisfactory performance, since they don't take into account the information content in the images. Here, we illustrate how the information theoretic metrics are superior to the quantitative metrics, for grayscale image fusion.
This paper considers an issue joint rate control and dynamic scheduling in mobile ad hoc networks. We propose a cross-layer rate control scheme that jointly computes both the rate allocation and dynamic scheduling. Th...
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This paper considers an issue joint rate control and dynamic scheduling in mobile ad hoc networks. We propose a cross-layer rate control scheme that jointly computes both the rate allocation and dynamic scheduling. The scheduling in ad hoc networks is a difficult problem and in general NP-hard, or requires centralized implementation. In this paper, we present a dynamic approximation algorithm adapted to mobile ad hoc networks. We study the case with dynamic arrivals and departures of the users. It is for the first time in the literature that the rescheduling is introduced to the network scheduling, and this rescheduling method can adapt to topology environment changed with high frequency. So this dynamic scheduling can suit the mobile ad hoc networks.
The exponential growth in wireless services has resulted in an overly crowded spectrum. The current state of spectrum allocation indicates that almost all usable frequencies have already been occupied. This makes one ...
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The exponential growth in wireless services has resulted in an overly crowded spectrum. The current state of spectrum allocation indicates that almost all usable frequencies have already been occupied. This makes one pessimistic about the feasibility of integrating emerging wireless services such as large-scale sensor networks into the existing communication infrastructure. Cognitive radio is the emerging dynamic spectrum access technology to achieve open spectrum sharing flexibly and efficiently. It is an intelligent wireless communication system that is aware of its radio environment and is capable of adapting its operation to statistical variations of the radio frequency. Ad-hoc networks in terms of cognitive radio rely on a common control channel (CCC) for operation. control signals are used to enable cooperation communicate through a common control channel. However, common control channel may not be always available in an open spectrum allocation scheme due to interference and coexistence with primary systems (PS) of the spectrum. In this paper, we propose a novel common control channel selection protocol (DCP-CCC) in a distributed way based on appearance patterns of PS and connectivity among nodes. Using simulation results, we evaluate the performance of the proposed CCC selection scheme.
An autoregressive channel prediction model is presented for cognitive radio systems. This model adopts a second-order AR model and a particle filter. In this paper, an AR model of order p is used to approximate the fl...
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An autoregressive channel prediction model is presented for cognitive radio systems. This model adopts a second-order AR model and a particle filter. In this paper, an AR model of order p is used to approximate the flat Rayleigh fading channels. Simulation results show that the performance of the proposed autoregressive channel prediction model based on particle filtering is better than that of Kalman filtering.
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