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This paper presents our new results on lucky ranging utilizing a towed array in environments subject to unknown fluctuating spatial coherence losses. We derive a lucky maximum likelihood range estimator based on the probabilistic assumption that each collected data snapshot is either coherent or purely incoherent with some probability. Our lucky range estimator can be interpreted as first ranking...
For passive ranging in environments subject to unknown fluctuating spatial coherence losses, we derive a new lucky maximum likelihood estimator based on the probabilistic assumption that each collected data snapshot is either coherent or purely incoherent with some probability. Our lucky range estimator can be interpreted as first ranking the coherence quality of each data snapshot according to an...
This work presents some new results on the structures of, and our interpretation on, the multi-rank filters used for passive wavefront curvature (WFC) ranging. Such a WFC ranging systems uses a large-scale distributed arrays with many spatially separated modular arrays, operating under environments subject to a spatial coherence loss. Working on the modular array level beamformed data, the multi-rank...
This work presents our data analysis results on modeling spatial coherence in a distributed passive array ranging system consisting of three volumetric module arrays. We show that a simple analytical approximation that was previously derived for modeling signal spatial coherence losses in wireless system which represented the random medium effects by a random scatter field can accurately model the...
In this work, the problem of multichannel cross-spectrum density (MCSD) estimation is studied. Based on a multichannel data model, the classic periodogram based MCSD estimator and the minimum variance (MV) based MCSD estimator are tested for cross-spectrum density estimation. Our major contribution in this work is a canonical correlation analysis (CCA) based MCSD estimator, relying on the inherent...
In this work, we present some asymptotic results on the maximum likelihood multi-rank processor for passive wavefront curvature ranging systems using large-scale distributed arrays. We assume that the operation environment for the distributed arrays is subject to a spatial coherence loss. Under an exponential coherence model, analytical expressions for the multi-rank combiners are derived. The results...
In this work, we study the eigen-structure of the data covariance matrix in an asynchronous CDMA system. Our results reveal the joint effect of spreading codes and power control on warp converging Wiener filters. We further provide suggestions on spreading code selection and power control strategy in CDMA system design, where stable and predictable early convergence of the reduced-rank conjugate gradient...
In this work we derive the maximum likelihood estimator for passive wavefront curvature ranging systems operating in environments subject to a spatial coherence loss. As a consequence of the spatial coherence loss, the optimum processor is no longer a rank-1 matched filter and now instead involves a multi-rank weighted combination of the data based on the coherence matrix eigenvectors and eigenvalues...
This work presents our analysis on adaptive beamforming and combining techniques applied to a system consisting of distributed antenna arrays. Our analysis reveals the connection between the theoretical and the practical schemes for data combination. The important roles played by the canonical correlations (CC), which may or may not exist among multiple data sets in a distributed antenna system, are...
In array signal processing, the performance of parameter estimation is effected by the unknown nonuniform perturbations on the sensors of receiver array. In this work, the problem of passive localization of near-field sources with partly calibrated subarray-based array is studied. Rank reduction (RARE) is extended to its 2-Dimensional version to solve this problem, and the CRBs on the ranges and bearings...
This work provides a canonical coordinates perspective for direction-of-arrival (DOA) estimation using two distributed sensor arrays. A new method for estimating the DOA of multiple far-field narrow-band sources is proposed. Distinct from existing asymptotic results for canonical correlation analysis (CCA) in such an application, our special interest lies in the realistic limited array size and sample...
This work presents our research results on the capability of passive source localization using a towed multi-module array in underwater acoustic environments. We developed new Cramer-Rao Lower Bound (CRLB) results for assessing the array's source localization capability under environmental uncertainties, such as array modules' positions and acoustic-field's spatial coherence. We also developed a two-stage...
This work proposes a method for localizing a single near-field source using a moving array. Using a phase correction factor calculated from two sequences of selected data snapshots, we extend the array aperture and compute the initial estimates of the source's bearing and range from the extended data sets. With the initial estimates of bearing and range we construct a phase difference factor to modify...
This work studies the effect of in-phase/quadrature (I/Q) imbalance on time-reversal space-time block coded (TR-STBC) communication systems operating over frequency-selective fading channels. The transceiver I/Q imbalance in a 2 times 1 TR orthogonal STBC (TR-OSTBC) system is studied in detail, and low-complexity mitigation solutions are proposed by exploiting the special structure of the received...
This work provides analytical results on the canonical correlation analysis (CCA) of data sets from two spatially separated arrays of sensors. Our case studies cover both single source and multiple source signals in either white or colored noise fields for array signal processing. We derive analytical expressions of the canonical correlation for these examples and present a computer simulation analysis...
In this work, a grouped linear constellation precoded orthogonal frequency-division multiplexing (GLCP OFDM) system, with the transceiver in-phase/quadrature (I/Q) imbalance operating over frequency-selective fading channels are studied. A new subcarrier grouping scheme in such a system is proposed. Through analysis and simulations, we demonstrate that with the proposed scheme, low-complexity solutions...
Maximum a posterior (MAP) estimator has been shown to perform perfectly for direction-of-arrival (DOA) under the assumption that the number of sources is known. Specifically, in this work we proposed a MAP estimator for DOA, and extend it to a new approach called DDBM for joint detection and DOA estimation simultaneously. Results of both simulation and experiment demonstrate that the proposed method...
In this work, the encoding/decoding scheme for the cyclic prefix (CP) based time-reversal quasi-orthogonal space-time block coded (TR-QOSTBC) wireless communication systems over frequency-selective fading channels is studied. A CP based 4 times 1 TR-QOSTBC system is studied in detail, and the upper bound of the pairwise error probability (PEP) is derived. Our analysis shows that the proposed scheme...
In this work we study the performance degradation caused by the in-phase/quadrature (I/Q) imbalance of the transceivers in multiple-input multiple-output (MIMO) space-time block coded (STBC) communication systems. The 2-Tx orthogonal STBC (OSTBC) systems, 4-Tx quasi-orthogonal STBC (QOSTBC) systems, and 4-Tx rotated QOSTBC (RQOSTBC) systems in the presence of I/Q imbalance are studied in detail. Our...
This work develops an iterative solution to maximum likelihood estimation of source parameters in unknown but partially correlated non-uniform noise field when a moving array is used for data collection. With the proposed solution, the temporal frequencies and the direction of arrivals (DoAs) of source signals can be obtained effectively. Computer simulated experiments are carried out to demonstrate...
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