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Satellite precision formation flying (PFF) is a concept in which multiple spacecraft communicate via an inter-satellite link (ISL) and cooperate to achieve the goal of a single, more complex satellite. This enables the creation of virtual scientific structures such as interferometers or imagers that would not be deployable in space because of their physical dimensions. PFF requires precise knowledge...
Acoustic frequency tracking of a harmonic signal with continuously varying frequency is considered. The Rao-Blackwellized point mass filter (RBPMF), previously proposed by the authors for mechanical vibration tracking, is applied to the problem. The RBPMF is compared with two periodogram-based methods, and the similarities and differences between them are explained. Both experimental and simulation...
We propose a diffusion expectation-maximization algorithm with adaptive combiner for distributed estimation over sensor networks. Due to the spatial distribution of the nodes, variation of node profile across the network is a common phenomena in real applications. The unreliable nodes exist and provide inaccurate estimates, which may be caused by high levels of noise or malicious attacks. Instead...
The article develops an information rates estimation method for communication channels with known data delivery routes. Conclusion about the sufficiency of Gaussian probability model usage for describing the distribution of intra-system interference with a large number of simultaneously transmitted signals is made. Derived expressions allow to determinate signal-to-interference ratios for estimating...
In this paper, we propose a method to improve the accuracy of GPS positioning in the environment where the satellite signal including error information is excluded and the satellite signal is reflected and distorted like urban area. Factors that degrade GPS positioning accuracy include time error, ionospheric error, tropospheric error, and multipath error. In order to compensate for this, various...
This work proposes a novel authentication method for identifying Unmanned Aerial Vehicles (UAVs) based on a channel-tap power. A ground control station utilized the channel-tap power as a radio-frequency fingerprint (RFF) to directly detect UAVs via physical (PHY) layer. The proposed authentication method uses the Neyman-Pearson test to discriminate between two UAVs, UAVI and UAVA, which are controlled...
An efficient subspace-based two-step direction finding method is proposed for uniform linear arrays. It improves the estimation accuracy for small sample size and coherent sources by diminishing the undesirable terms and utilizing the Toeplitz structure of the sample covariance matrix. Furthermore, it works well even using single snapshot, therefore, it is a good candidate to track the direction-of-arrival...
The paper presents a new method for estimating capacity of real communication channel in the absence of noise when PSK-n signals are used under conditions of strong intersymbol distortion caused by transient processes in selective systems of a linear radio path. The presented method has high accuracy and low computational complexity, which does not depend on the number of discrete states of the PSK-n...
A random-vector-based beamforming scheme for Millimeter-Wave (mm-Wave) MIMO systems with asymptotic optimal performance at low signal-to-noise ratio (SNR) is proposed in this paper. Through transmitting random vectors from transmitter (TX) to receiver (RX) then back to TX, the proposed scheme can obtain the estimation of channel auto-correlation with low complexity operations and then obtain the nearly...
Using the minimum number of broadcasts to flood information in a vehicle network so that the maximum number of vehicles receives the information is a critical issue. Up to now, no research reports show the relationship between broadcast radius and success rate, the one-hop broadcast efficiency (i.e., the ratio of nodes that successfully received nodes to all nodes within the broadcast range). Determining...
In this paper, we investigate the performance of mobile vehicle positioning based on signal propagation delay estimation in the uplink case for a realistic propagation environment. In order to optimize the ranging performance, we introduce a parametric waveform. This waveform contains a scalar parameter for adjusting the distribution of the available signal power over the frequency. The optimization...
A minimum mean square error estimation (MMSE) using a virtual pilot channel estimation scheme was proposed by our researchers for improving the error performance of the IEEE 802.11p. However, compared to the STA channel estimation scheme, the MMSE scheme cannot provide an acceptable error performance in a low SNR region. To alleviate this, we propose an adaptive channel estimation scheme, which selectively...
This study is summary of research results of existing voice information security estimation approach analysis and modification, especially by change of immediate appreciation test conditions, along with considering speech forcing effect, adjustment of frequency range width and the method of its division, analysis of amplitude speech constitution and qualification of test signal level. Another point...
Consider random linear estimation with Gaussian measurement matrices and noise. One can compute infinitesimal variations of the mutual information under infinitesimal variations of the signal-to-noise ratio or of the measurement rate. We discuss how each variation is related to the minimum mean-square error and deduce that the two variations are directly connected through a very simple identity. The...
This paper presents a study of MUSIC algorithm for a nonuniform linear array (NLA) with different configurations. In the case of the same number of sensors, the element spacing of each configuration is selected according to the condition of the Chinese surplus theorem. In the simulation, we provide simulations of three typical NLA configurations for the different aperture of the array in comparison...
Since most energetic celestial sources in the Universe often exhibit a point-like appearance in the observed images, design of methods to detect and extract them is a hot research topic. An approach to detect and extract point sources in X-ray astronomical images that uses Gaussian smooth filters is proposed. As there might be false detections, a spurious source removal approach taking advantage of...
Linear frequency modulated continuous wave (LFMCW) signal has been widely used in the new system radar as the progress of radar technology. It is difficult to estimate the parameters of the LFMCW signal under noncooperative circumstances. In this paper, we introduce the time frequency analysis methods to signal representation and parameter estimation. The S-Method with adaptive window is proposed...
LTE evolved Multimedia Broadcast/Multicast Service (eMBMS) is an attractive solution for video delivery to very large groups in crowded venues. However, deployment and management of eMBMS systems is challenging, due to the lack of realtime feedback from the User Equipment (UEs). Therefore, we present the Dynamic Monitoring (DyMo) system for low-overhead feedback collection. DyMo leverages eMBMS for...
In the presence of environmental noise, speaker verification systems inevitably see a decrease in performance. This paper proposes the (1) use of two parallel classifiers, (2) feature enhancement based on blind signal-to-noise ratio (SNR) estimation and (3) fusion, to improve the performance of speaker verification systems. The two classifiers are based on Gaussian mixture models and the partial least-squares...
In this paper, a modified Wiener filtering speech enhancement algorithm with phase spectrum compensation is proposed, which aims at improving performance of typical Wiener filtering speech enhancement algorithm in low signal-noise ratio. Since typical speech enhancement algorithms always used the observed noisy speech phase spectrum unchanged directly as enhanced speech phase spectrum, and estimated...
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