In presence of targets that respond to transmitter diversity such as polarization, to maximize the output SINR, it becomes necessary to jointly optimize the transmit signal vector and the receiver bank of filters in p...
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ISBN:
(纸本)0780363396
In presence of targets that respond to transmitter diversity such as polarization, to maximize the output SINR, it becomes necessary to jointly optimize the transmit signal vector and the receiver bank of filters in presence of signal dependent interference and noise. This multichannel matched transmitter-receiver structure is superior to its scalar counterpart, since several aspects of the signal dependent interference spectrum are "brought to light" in this case. The cross-interference spectral matrices infact contain much more information compared to the single channel case, and despite the highly nonlinear nature of the problem, it is possible to derive a closed form solution for the optimum matched receiver filter bank. lit addition, an iterative algorithm that appears to converge for all SINR is proposed to determine the optimum transmit signal vector.
One of the important problems in ocean acoustics is to localize an underwater wideband sound source from the array hydrophone data. Among the algorithms developed, estimation of source parameters via maximum likelihoo...
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A quantitative model for interferogram data collected in a quantum-limited hyperspectral imaging system is derived. This model accounts for the geometry of the interferometer the Poisson noise, and the parameterizatio...
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ISBN:
(纸本)0780363396
A quantitative model for interferogram data collected in a quantum-limited hyperspectral imaging system is derived. This model accounts for the geometry of the interferometer the Poisson noise, and the parameterization of the mean of the noise in terms of the autocorrelation function of the incident optical signal. An estimation-theoretic approach to recovering the image spectrum is derived, based on the likelihood function for the received data. The computations proposed constitute an alternating minimization algorithm.
Capacity analysis of sensor networks or wireless ad hoc networks has attracted a great attention in the past years. But the research in this area has primarily focused on scaling laws of arbitrary or random network in...
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ISBN:
(纸本)1424403081
Capacity analysis of sensor networks or wireless ad hoc networks has attracted a great attention in the past years. But the research in this area has primarily focused on scaling laws of arbitrary or random network instead of the exact capacity of given topologies. While the insight into how the capacity of an arbitrary or random network scales with the number of nodes in a given area is important, the exact capacity of a network depends on the network topology and can be more desirable in practice. In this paper, we compare the throughput of a large network with three possible topologies: square (rectangular), hexagonal and triangular. With a given topology, the network throughput also depends on the choice of routing protocols. We follow a synchronous array method (SAM) that is known so far to yield the highest throughout of a network on a rectangular grid.
Iterative quadratic maximum likelihood (IQML) is an efficient approach for estimating the directions of arrival (DOA) of signals impinging on a uniform linear array. It is desirable to apply the IQML method in beamspa...
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ISBN:
(纸本)0780363396
Iterative quadratic maximum likelihood (IQML) is an efficient approach for estimating the directions of arrival (DOA) of signals impinging on a uniform linear array. It is desirable to apply the IQML method in beamspace SO as to take advantage of the benefits of beamspace operations in terms of reduced computational complexity and improved resolution thresholds. The difficulty with beamspace IQML is that the Vandermonde structure of the array manifold may not preserve during the beamspace transformation. We tackle this obstacle using discrete Fourier transform (DFT) beams and derive a parameterized polynomial in the beamspace dimension. The proposed beamspace IQML algorithm is computationally efficient, and provides satisfactory estimation results.
We describe the problem of joint sensing and communications (JSAC) using an antenna array where some antennas are used for sensing and some others for communications. The problem is to jointly optimize the sensing and...
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ISBN:
(纸本)9798350344820;9798350344813
We describe the problem of joint sensing and communications (JSAC) using an antenna array where some antennas are used for sensing and some others for communications. The problem is to jointly optimize the sensing and communications performance at the receive side through respectively the CramerRao bound (CRB) on the source angles and the variance of the sources after applying a minimum variance distortionless response (MVDR) beamformer. Both criteria are derived under a two-source scenario and optimized for any position of the two sources. Here one of the sources is considered the source of interest, while the other one models the interference. The performance criteria for sensing and communications are mathematically similar and depend only on the angular difference between the two sources. As a result, they can be elegantly combined and jointly optimized. Our findings are corroborated by simulations under different parameter settings.
For the element position synthesis of 2-dimension sparse rectangular arrays with the design constraints of the number of elements, the aperture and the minimum element spacing, an improved genetic algorithm (IGA) base...
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ISBN:
(纸本)1424403081
For the element position synthesis of 2-dimension sparse rectangular arrays with the design constraints of the number of elements, the aperture and the minimum element spacing, an improved genetic algorithm (IGA) based on chromosome element resetting is presented in this paper. Compared with the synthesis method of thinned arrays, this new approach could exploit more degree of freedom of elements to control the characters of the sparse arrays. When the aperture, the number of elements and the minimum element spacing are fixed identical, the new approach can make the sparse plane array produce lower peak sidelobe level (PSLL). The simulated results show that the fitness function value of thinned plane arrays with 108 elements mentioned by Haupt can reduce 5.626dB when the minimum element spacing of half wavelength was introduced into the optimization. And as well, the great efficiency and the robustness of IGA are shown in this paper.
Performing surgery on the beating heart has significant advantages for the patient compared to traditional heart surgery on the stopped heart. A remote-controlled robot can be used to automatically cancel out the move...
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ISBN:
(纸本)9781479914814
Performing surgery on the beating heart has significant advantages for the patient compared to traditional heart surgery on the stopped heart. A remote-controlled robot can be used to automatically cancel out the movement of the beating heart. This necessitates precise tracking of the heart surface. For this purpose, we track 24 identical artificial markers placed on the heart. This creates a data association problem, because it is not known which measurement was obtained from which marker. To solve this problem, we apply a multiple target tracking method based on a symmetric kernel transformation. This method allows efficient handling of the data association problem even for a reasonably large number of targets. We demonstrate how to implement this method efficiently. The proposed approach is evaluated on in-vivo data of a real beating heart surgery performed on a porcine beating heart.
We study the problem of sensor fusion in a simplified radar surveillance application. A potentially large number of narrowband radars with isotropic antennas monitor a two-dimensional area for an unknown number of tar...
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ISBN:
(纸本)9781467310710
We study the problem of sensor fusion in a simplified radar surveillance application. A potentially large number of narrowband radars with isotropic antennas monitor a two-dimensional area for an unknown number of targets. We use techniques from compressive sensing to distribute efficient projections of network observations, allowing for reconstruction of the target scene using a single snapshot of sensor data. We avoid the use of a fusion node, allowing all radars to individually estimate target locations after iterative communication with neighboring sensors. We study the robustness of the discretization of continuous target locations, comparing estimation performance of basis pursuit reconstruction methods to a sparse estimator based on a model-robust formulation. We test the approach on simulated scenarios, showing tradeoffs in the resolution of target localization as well as the communication bandwidths required for this inter-radar cooperation scheme.
In this paper we address a new approach to solving the radar imaging problems stated and treated as ill-posed inverse problems of restoration of the spatial spectrum pattern of the wavefield sources distributed in the...
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ISBN:
(纸本)0780375513
In this paper we address a new approach to solving the radar imaging problems stated and treated as ill-posed inverse problems of restoration of the spatial spectrum pattern of the wavefield sources distributed in the environment by processing the radar data signals distorted in the stochastic measurement channel. By exploiting the idea of combining the experiment design (ED) and descriptive regularization (R) theory methods for scattering inverse problems solution we propose a fused experiment-design-regularization (EDR) technique for radar image formation. With this technique we present the EDR-based interpretation of a family of the conventional array imaging algorithms and propose some their modifications to enhance the resolution performances of the resulting radar images.
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