1,545 research outputs found

    Seamless Heterogeneous Handoff Based on SAP

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    Contemporarily there has been a number of techniques being suggested and used for heterogeneous handoff hitch. Different types of decision making methods are being implemented for handoff impediment. Mobile terminals progressing in neighbourhood will incur a handoff when its link capacity decreases below the threshold level. Various types of Multiple Attribute Decision Making methods have been exploited for handoff decision making. Here we have used a novel Reliable Seamless Handoff such as Simple Analytical Process method which uses Analytical Hierarchy Process for predicting the criterion weights and employed Simple Additive Weighting method for handoff decision making. Alternatives such as GSM, CDMA and EDGE networks are used. Data Rate, Packet Loss, Velocity, Bandwidth, Dwell time and Jitter are the parameters applied

    Differential phase pattern of the CSU CHILL radar antenna, The

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    Includes bibliographical references (pages 1122-1123).The measurement of the differential propagation phase and copolar correlation coefficient are affected by the differential phase pattern of the antenna system when operating in an alternate horizontal and vertical transmitting scheme. Direct phase pattern measurements of a large dish such as that of the CSU CHILL is difficult because of the need to obtain phase reference. A simple technique is devised to measure the differential phase pattern of the CSU CHILL antenna system. The measurements are subsequently used in the evaluation of the antenna imposed limit on the copolar correlation coefficient

    Improved QoS and avoidance of black hole attacks in MANET using trust detection framework

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    In recent times, secured routing is a major research in MANETs. The behaviour of malicious nodes in this network increases the risk of threats and induces abnormal operations in MANETs. This affects the security of data transmitted between the nodes in the network. Hence, an effective technique is needed to prevent the abnormal nodes after the process of detection. In this paper, we propose an improved Trust Detection Algorithm to increase the probability of detection and prevention of Black Hole nodes in MANETs. The proposed framework observes the behaviour of each node using various trust metrics that includes the relationship between the sensor nodes, social and service attribute trust and QoS metric trusts. The behaviour of sensor nodes is found through the communication and mobility behaviour of each node. This method avoids the black hole nodes in MANETs, when the routing is carried out with Zone Routing Protocol (ZRP). Hence, the privacy of data is retained using the proposed method. The proposed method is tested in terms of different combinations of with and without trusts. The result shows that the proposed method is effective through various QoS metrics like overall throughput, packet loss, energy consumption, trust level, false acceptance rate and missed detection rate

    A nonlocal connection between certain linear and nonlinear ordinary differential equations/oscillators

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    We explore a nonlocal connection between certain linear and nonlinear ordinary differential equations (ODEs), representing physically important oscillator systems, and identify a class of integrable nonlinear ODEs of any order. We also devise a method to derive explicit general solutions of the nonlinear ODEs. Interestingly, many well known integrable models can be accommodated into our scheme and our procedure thereby provides further understanding of these models.Comment: 12 pages. J. Phys. A: Math. Gen. 39 (2006) in pres

    ZA-APA with Adaptive Zero Attractor Controller for Variable Sparsity Environment

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    The zero attraction affine projection algorithm (ZA-APA) achieves better performance in terms of convergence rate and steady state error than standard APA when the system is sparse. It uses l1 norm penalty to exploit sparsity of the channel. The performance of ZA-APA depends on the value of zero attractor controller. Moreover a fixed attractor controller is not suitable for varying sparsity environment. This paper proposes an optimal adaptive zero attractor controller based on Mean Square Deviation (MSD) error to work in variable sparsity environment. Experiments were conducted to prove the suitability of the proposed algorithm for identification of unknown variable sparse system

    Towards a Radar/Radiometer Mode on the Dual-Frequency, Dual-Polarized, Doppler Radar (D3R) System

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    The dual-frequency, dual-polarized, Doppler radar (D3R) system was developed in support of the ground validation segment of the Global Precipitation Measurement (GPM) mission. Although its main purpose is to provide active, Ku/Kaband, dualpolarized measurements of precipitation, the design presents an opportunity to study its operation in an active/passive mode. The opportunity arises from use of solid-state transmitters employing a multifrequency waveform and receiving system. Typically, a sequence of three pulses separated in frequency is transmitted to achieve its radar sensitivity and minimum range. However, one of the three pulses can be disabled with a tolerable decrease in sensitivity and its receive channel can be repurposed to support passive measurements. This work focuses on progress in the characterization of the Ku-band H polarized passive channel operating simultaneously with two active as a step towards the provision of brightness temperatures along with the other radar derived products. The methodology developed will be applied to the V polarized channel and Kaband subsystem in the near future. The study consists on the analysis of the antenna performance, receiver architecture, transfer function and achievable number of independent samples, calibration method and preliminary observation analysis. All within the context of the instrument's current configuration and possible future improvements
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