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Max-min fair power allocation brings higher aver- age throughput and better utilization of the resources than a work-conserving equal-sharing policy. In this paper, instead of achieving a common maximum sum-rate objective, an optimal power-allocation design for maximizing the minimum rate of the reverse link of code-division multiple-access (CDMA) systems with quality-of-service (QoS) constraints is investigated. To avoid the difficulty of directly solving a nonconvex optimization problem, we split the original problem into two successive steps. First, we try to derive the structure of the optimum solution via majorization theory. Then, based on this result, we propose a very efficient search method to find the max-min fair solution, which reduces the search space from a 1-D space into a finite set of points. Compared with existing methods, a much lighter computational complexity is required by our method. [ABSTRACT FROM AUTHOR]

In this paper, a new direction of arrival (DOA) estimation method is proposed in the presence of unknown mutual coupling. The impinging signals are a mixture of signals in different correlation degrees, which are uncorrelated, partially correlated or coherent with each other. The method proceeds in three steps. The noncoherent (uncorrelated or partially correlated) signals are firstly estimated with unknown mutual coupling. Then these estimates are utilized to get the mutual coupling coefficients. Finally, by eliminating the contributions of the noncoherent signals and compensating the mutual coupling effect, only coherent signals remain to be estimated. This method is simple but effective and does not need iterative processing. Simulation results demonstrate the effectiveness and performance of the proposed method. [ABSTRACT FROM AUTHOR]

In order to get the information about multipath propagation, this communication presents two estimation methods for slowly varying fading coefficients. With known numbers of the far-field sources and multipaths from each far-field source, the fading coefficients in multipath propagation can be well estimated. The methods not only have low complexity but also have high performance, and the fading coefficients can be resolved directly without a searching procedure. Afterwards, we make an extension to further improve the estimation accuracy of both direction of arrival (DOA) and fading coefficients after obtaining their estimations. The Cramer-Rao bound (CRB) for this problem is also deduced. Simulation results demonstrate the effectiveness and efficiency of the proposed methods. [ABSTRACT FROM AUTHOR]

An algorithm is presented for direction-of-arrival (DOA) estimation in the presence of unknown mutual coupling based on the generalized eigenvalues utilizing signal subspace eigenvectors (GEESE) algorithm for uniform linear array (ULA). It is not an iterative algorithm, and a spectral peak search is not required. The DOA can be accurately estimated without any calibration sources since the effects of mutual coupling can be eliminated by the inherent mechanism of the proposed algorithm. An algorithm for estimating the mutual coupling coefficients is also proposed. Simulation results demonstrate the effectiveness of the proposed algorithms. [ABSTRACT FROM AUTHOR]

We present a 2-D direction of arrival (DOA) estimation algorithm in the presence of unknown mutual coupling for the uniform rectangular array (URA) based on the multiple signal classification (MUSIC) algorithm. By setting the sensors on the boundary of the URA as auxiliary sensors, it can accurately estimate the DOAs without any calibration sources or iterative operations. We prove that the effect of mutual coupling can be eliminated by the inherent mechanism of the proposed method. Twice search technique is used to reduce the computation of the 2-D spectrum search. Moreover, we provide a method to estimate the mutual coupling coefficients after getting the DOA estimates. Simulation results confirm the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

A novel robust linear receiver with worst-case probability guarantee is proposed in this correspondence. Based on multivariate Chebyshev inequality, deterministic expressions of the probabilistic constraints are derived, and then, an iterative second-order cone programming is developed to obtain the robust solutions. Compared to the existing receivers, our proposed receiver improves performance by allowing a small outage probability and a more general uncertainty model. Simulations illustrate the improvement of our proposed approach. [ABSTRACT FROM AUTHOR]

Many classical direction of arrival (DOA) estimation algorithms suffer from sensitivity to sensor coupling. By applying a group of auxiliary sensors in a uniform linear array (ULA), we prove the resiliency of the MUSIC direction finding algorithm against array sensor coupling. We show that the performance of MUSIC algorithm under antenna array with unknown coupling can be very close to the case with known coupling. We can also estimate the mutual coupling coefficients before refining the DOA estimates by utilizing an extended sensor array. Moreover, our analysis on the effect of mutual coupling in direction finding illustrates the existence of some blind angles which should be avoided when the array is designed. Our simulation results corroborate our analysis. [ABSTRACT FROM AUTHOR]

A new direction of arrival (DOA) estimation method is proposed for uniform linear array in this paper when both uncorrelated and coherent sources are present. The uncorrelated and coherent sources are estimated at two different stages. The uncorrelated sources are first estimated using conventional subspace methods, and then they are eliminated by exploiting the symmetric configuration of the array. Finally the remaining coherent sources are estimated by reconstructing a non-Toeplitz matrix. The number of sources resolved by our method can exceed the number of array elements. Simulation results demonstrate the effectiveness and efficiency of our proposed method. [ABSTRACT FROM AUTHOR]

Histogram equalization (HE) is a simple and effective image enhancing technique, however, it tends to change the mean brightness of the image to the middle level of the permitted range, and hence is not very suitable for consumer electronic products, where preserving the original brightness is essential to avoid annoying artifacts. This paper proposes a novel extension of histogram equalization, actually histogram specification, to overcome such drawback as HE. To maximize the entropy is the essential idea of HE to make the histogram as flat as possible. Following that, the essence of the proposed algorithm, named Brightness Preserving Histogram Equalization with Maximum Entropy (BPHEME), tries to find, by the variational approach, the target histogram that maximizes the entropy, under the constraints that the mean brightness is fixed, then transforms the original histogram to that target one using histogram specification. Comparing to the existing methods including HE, Brightness preserving Bi-Histogram Equalization (BBHE), equal area Dualistic Sub-Image Histogram Equalization (DSIHE), and Minimum Mean Brightness Error Bi-Histogram Equalization (MMBEBHE), experimental results show that BPHEME can not only enhance the image effectively, but also preserve the original brightness quite well, so that it is possible to be utilized in consumer electronic products. [ABSTRACT FROM AUTHOR]

In this paper, an efficient greedy scheduler for zero-forcing dirty-paper coding (ZF-DPC), which can be incorporated in complex Householder QR factorization of the channel matrix, is proposed. The ratio of the complexity of the proposed scheduler to the complexity of the channel matrix factorization required by ZF-DPC is O(M-1), while such ratio for the original greedy scheduler is O(M), where M is the number of transmitters. Therefore, the new scheduler reduces the overhead of scheduling from being the bottleneck of ZF-DPC to being negligible. [ABSTRACT FROM AUTHOR]

This study introduces an action descriptor that has the ability to perform human action recognition efficiently for one and two person(s). The authors' proposed descriptor computes information like motion, spatial-temporal, diversion with respect to the centroid, critical point and keypoint detection, whereas the existing approaches lack to address this information efficiently. Action descriptors are developed from signature-based optical flow, signature-based corner points and binary robust invariant scalable keypoints. These action descriptors are applied to silhouette and silhouette's skeleton frames. These aforementioned action descriptors lead to developing the concatenated action descriptor (CAD). In order to develop action descriptors, the reference video frame plays an important role. Weizmann (one person) and both clean and noise versions of SBU Kinect Interaction (two persons) datasets are used for the evaluation of their proposed descriptors. On the other hand, classifications are performed by using support vector machine. Experimental results demonstrate that CAD not only outperforms among the entire proposed descriptors, but also provides better performance as compared to state-of-the-art approaches. [ABSTRACT FROM AUTHOR]

A new rank reduction (RARE)-based two-dimensional (2-D) direction of arrival (DOA) estimation algorithm is proposed considering a mixture of circular and strictly noncircular sources. To enhance array aperture, a geometry of three uniform linear arrays is considered and then treated as displaced arrays from a virtual array using a simple linear transformation. The received data and the conjugated counterpart are combined together, exploiting the noncircular property. Both sources can be estimated separately by designing and exploiting the distinctive nature of circular and noncircular steering vectors. However, a 2-D spectrum search would lead to a high computational complexity burden. To reduce this high computational complexity burden, a novel RARE-based method is proposed, which plays a vital role by decomposing 2-D observation space into two successive 1-D peak search functions. The proposed method has some distinctive advantages: it can enhance the array aperture utilization, it can provide better estimation accuracy when mixed sources are greater than the number of sensors, it can estimate a larger number of mixed sources than the number of sensors, and finally it can automatically pair 2-D DOAs without any complicated pairing formulation. Extensive simulation results are provided to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This communication considers the problem of direction-of-arrival (DOA) estimation for multiple uncorrelated noncircular signals in the presence of mutual coupling. A method is proposed to eliminate the effect of mutual coupling for uniform linear arrays (ULAs). By taking advantage of the special structure of the mutual coupling matrix, the mutual coupling free covariance matrix and elliptic covariance matrix, the mutual coupling coefficients can be estimated using an iterative algorithm. The estimated mutual coupling coefficients can be embedded within any DOA estimation algorithm for circular signals or noncircular signals. Simulation results demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Detection of cosmic-ray hits is important because of their disturbing effects on image processing. An algorithm based on gray-scale morphology to detect cosmic-rays in single spectroscopic CCD images is presented in this paper. Based on the morphological differences between cosmic-ray hits and spectra, the operations of erosion and dilation are used to deal with images successively, with appropriate structuring elements. Points of cosmic-ray hits can be detected by analyzing the variation between data pre- and post-operation. Examples of the algorithm are given at the end of this paper, with several groups of both simulated LAMOST images and observed SDSS images to show its performance. [ABSTRACT FROM AUTHOR]