In this paper, we propose the joint scheme for multicarrier code-division multiple access (MC-CDMA) systems which estimates the frequency offset for the desired user and eliminates the multiuser interference (MUI), jo...
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In this paper, we propose the joint scheme for multicarrier code-division multiple access (MC-CDMA) systems which estimates the frequency offset for the desired user and eliminates the multiuser interference (MUI), jointly. In the proposed scheme, firstly the well-known constrained minimum output energy (MOE) detector is designed under the condition that the frequency offset estimate of the desired user is known. Then, the frequency offset estimate is obtained by searching the value which maximizes the output energy of the conditional MOE detector. Finally, the frequency offset estimate is used for the conditional MOE weight vector, and the joint work is comp.eted. The analytical expression for the estimation error of the proposed frequency offset estimator is derived and comp.red with the simulation results. Another simulation results show that the frequency offset estimate is very close to the true value and the bit error rate (BER) of the proposed scheme is comp.rable to that of the MOE detector with the perfect frequency offset comp.nsation.
We consider the problem of two-dimensional (azimuth and elevation) direct ion-of-arrival estimation for coherently distributed sources using a pair of uniform circular arrays. We propose a low-comp.exity estimation al...
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We consider the problem of two-dimensional (azimuth and elevation) direct ion-of-arrival estimation for coherently distributed sources using a pair of uniform circular arrays. We propose a low-comp.exity estimation algorithm, the sequential one-dimensional searching algorithm. The proposed algorithm has a basis on the eigenstructure between the steering matrix and signal subspace, and utilizes a preliminary estimate obtained by the total least square estimation of signal parameters via rotational invariance technique as a pre-processing stage. The proposed algorithm exhibits as good estimation performance as the maximum likelihood method for coherently distributed sources. Some simulation results are included to show the performance of the proposed method.
Packet classification is an important comp.nent of new Internet routers to support various services such as quality of service guarantee and virtual private network. Basically, packet classification can be considered ...
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Packet classification is an important comp.nent of new Internet routers to support various services such as quality of service guarantee and virtual private network. Basically, packet classification can be considered as a process looking for the best matching filter in a filter set for several fields selected from packet header. Various data structures and search algorithms have been proposed for such multi-field packet classification. In particular, the Nested binary tuple space search algorithm presented in [16] was designed for two-field conflict free filter sets. The time comp.exity of the Nested binary search algorithm is (⌈log(w + 1)⌉)2, where W is the length of the fields. To ensure that the filter set is conflict free, the authors assumed that conflicts are resolved by adding resolution filters. In this paper, we propose a novel search algorithm which can find the best matching filter in 2⌈log(W + 1)⌉ probes. Although more resolution filters are added, empirical results for random filter sets show that our scheme requires less memory than the Nested binary search algorithm because no primary markers (and the secondary markers of primary markers) are needed.
In this paper, we propose a low comp.exity blind space-time multiuser detector for multipath fading channel in DS/CDMA systems. The conventional blind space-time multiuser detector uses MOE (minimum output energy) det...
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In this paper, we propose a low comp.exity blind space-time multiuser detector for multipath fading channel in DS/CDMA systems. The conventional blind space-time multiuser detector uses MOE (minimum output energy) detectors to suppress interference and MRC (maximum ratio combiner) to obtain spatial and temporal diversity. But this receiver has disadvantage that the number of MOE detectors grows with the number of resolvable multipaths. The proposed spacetime multiuser detector reduces the number of detectors using MV (minimum variance) detection scheme. It is shown that one MV detector has the same performance as many MOE detectors as the number of multipaths. From this result, a fewer blind multiuser detectors are required in the proposed scheme. Simulation results show that MV detector has the same performance as MOE detectors with MRC and the proposed scheme exhibits better performance than the conventional scheme.
In this paper, we present a novel symmetry-based coarse classification method for the preclassification of printed Chinese characters. The proposed method consists of two main modules, recursive radical extraction, an...
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In this paper, we present a novel symmetry-based coarse classification method for the preclassification of printed Chinese characters. The proposed method consists of two main modules, recursive radical extraction, and a symmetry test. The former classifies Chinese characters into ten classes according to the comp.sing structure of the characters. Two classes in the ten classes, left-right, and up-down type characters, contain over 85% of the total characters. The latter performs the symmetry test to determine whether the character, or radical in the ten classes, is symmetric or not. The main purpose of the proposed symmetry-test coarse classification method is to reduce the number of characters in each of the ten classes. Four symmetry features are devised to perform the symmetry test. Experimental results reveal that the proposed method can greatly reduce the number of characters in each class to achieve the coarse classification goal.
The alkylation of 2-amino-6-nitro- and 2,6-diaminobenzothiazoles by ethylene chlorohydrin has been studied. A comp.rative analysis has been made of the comp.sition of these reaction mixtures and of those obtained from...
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The alkylation of 2-amino-6-nitro- and 2,6-diaminobenzothiazoles by ethylene chlorohydrin has been studied. A comp.rative analysis has been made of the comp.sition of these reaction mixtures and of those obtained from other 2-aminobenzothiazoles using this reaction. The structure of the synthesized comp.unds was confirmed using IR and 1H NMR spectroscopy, mass spectrometry, and X-ray diffraction and via alternative syntheses.
In many multimedia applications, there is a need to authenticate a source that has been subjected to benign degradations in addition to potential tampering attacks. We develop a meaningful formulation of this problem,...
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In many multimedia applications, there is a need to authenticate a source that has been subjected to benign degradations in addition to potential tampering attacks. We develop a meaningful formulation of this problem, and identify and interpret the associated information-theoretic performance limits. The associated systems are shown to perform dramatically better than frequently proposed approaches based on information embedding techniques.
We present here a thermoelectric transport property study of Bi1-xSbx alloy nanowires embedded in a dielectric matrix. Temperature-dependent resistance measurements exhibit non-monotonic trends as the antimony mole fr...
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We present here a thermoelectric transport property study of Bi1-xSbx alloy nanowires embedded in a dielectric matrix. Temperature-dependent resistance measurements exhibit non-monotonic trends as the antimony mole fraction (x) increases, and a theoretical model is presented to explain the features that are related to the unusual band structure of Bi1-xSbx systems. Seebeck coefficient measurements are performed on nanowires with different diameters and comp.sitions, showing enhanced thermopower over bulk Bi. The magneto-Seebeck coefficient of these nanowires also exhibits an unusual field dependence that is absent in bulk samples.
A query optimizer requires selectivity estimation of a query to choose the most efficient access plan. An effective method of selectivity estimation for the future locations of moving objects has not yet been proposed...
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ISBN:
(纸本)9781581134971
A query optimizer requires selectivity estimation of a query to choose the most efficient access plan. An effective method of selectivity estimation for the future locations of moving objects has not yet been proposed. Existing methods for spatial selectivity estimation do not accurately estimate the selectivity of a query to moving objects, because they do not consider the future locations of moving objects, which change continuously as time passes. In this paper, we propose an effective method for spatio-temporal selectivity estimation to solve this problem. We present analytical formulas which accurately calculate the selectivity of a spatio-temporal query as a function of spatio-temporal information. Extensive experimental results show that our proposed method accurately estimates the selectivity over various queries to spatio-temporal data combining real-life spatial data and synthetic temporal data. When Tiger/lines is used as real-life spatial data, the application of an existing method for spatial selectivity estimation to the estimation of the selectivity of a query to moving objects has the average error ratio from 14% to 85%, whereas our method for spatio-temporal selectivity estimation has the average error ratio from 9% to 23%.
The use of Raman spectroscopy as a characterization tool for individual single wall carbon nanotubes is briefly reviewed. New physical phenomena occurring at the single nanotube level are discussed, with special empha...
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The use of Raman spectroscopy as a characterization tool for individual single wall carbon nanotubes is briefly reviewed. New physical phenomena occurring at the single nanotube level are discussed, with special emphasis given to the use of resonance Raman scattering for the structural determination of (n, m) for individual nanotubes, based on diameter and chirality dependent phenomena associated with the radial breathing mode, the G-band and the G′-band features. Examples are given to show how single nanotube spectroscopy provides insight into the use of Raman spectroscopy for the characterization of nanotube bundles and for the study of new physical phenomena occurring at the single nanotube level.
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