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Minimal axiom group of similarity-based rough set model
DAI Jian-hua, PAN Yun-he
Front. Electr. Electron. Eng.. 2006, 1 (3): 255-258.
https://doi.org/10.1007/s11460-006-0008-1
Rough set axiomatization is one aspect of rough set study to characterize rough set theory using dependable and minimal axiom groups. Thus, rough set theory can be studied by logic and axiom system methods. The classical rough set theory is based on equivalence relation, but the rough set theory based on similarity relation has wide applications in the real world. To characterize similarity-based rough set theory, an axiom group named S, consisting of 3 axioms, is proposed. The reliability of the axiom group, which shows that characterizing of rough set theory based on similarity relation is rational, is proved. Simultaneously, the minimization of the axiom group, which requests that each axiom is an equation and independent, is proved. The axiom group is helpful to research rough set theory by logic and axiom system methods.
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Separating cyclostationary signals from spectrally overlapping interference
GUO Jie, LIU Yun, YE Zhi-hui, SONG Tie-cheng, SHEN Lian-feng
Front. Electr. Electron. Eng.. 2006, 1 (3): 307-312.
https://doi.org/10.1007/s11460-006-0002-7
This paper studies an algorithm about separating spectrally overlapping signals using the cyclostationary properties of signals. On the basis of direct sequence spread system (DSSS), frequency shift filter is added into the receiver of the communication system. Although the structure of frequency shift filter is more complicated than the time-domain filter, it uses both time correlations and frequency spectrum correlations so it can achieve better performances on separating the overlapping signals. After the analysis of cyclostationary characteristic and frequency spectrum correlation, the structure of the frequency shift filter can be gained. Then, a self-adaptive algorithm is utilized for the purpose of achieving optimum multidimensional tap weights of frequency shift components. The simulation results indicate that this method can efficiently separate overlapping signals, and its error rate is lower than the time-domain filter or DSSS system by two orders of magnitude on the condition that high-power interference is added into the system.
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Study of a new fast adaptive filtering algorithm
WANG Zhen-li, ZHANG Xiong-wei, YANG Ji-bin, CHEN Gong
Front. Electr. Electron. Eng.. 2006, 1 (3): 334-339.
https://doi.org/10.1007/s11460-006-0027-y
A new fast adaptive filtering algorithm was presented by using the correlations between the signal s former and latter sampling times. The proof of the new algorithm was also presented, which showed that its optimal weight vector was the solution of generalized Wiener equation. The new algorithm was of simple structure, fast convergence, and less stable maladjustment. It can handle many signals including both uncorrelated signal and strong correlation signal. However, its computational complexity was comparable to that of the normalized least-mean-square (NLMS) algorithm. Simulation results show that for uncorrelated signals, the stable maladjustment of the proposed algorithm is less than that of the VS-NLMS algorithm, and its convergence is comparable to that of the algorithm proposed in references but faster than that of L.E-LMS algorithm. For strong correlation signal, its performance is superior to those of the NLMS algorithm and DCR-LMS algorithm.
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Construction of generalized binary Bent sequences
KE Pin-hui, KE Pin-hui, CHANG Zu-ling, CHANG Zu-ling, WEN Qiao-yan, WEN Qiao-yan
Front. Electr. Electron. Eng.. 2006, 1 (3): 340-344.
https://doi.org/10.1007/s11460-006-0045-9
Bent functions in trace forms play an important role in the constructions of generalized binary Bent sequences. Trace representation of some degree two Bent functions are presented in this paper. A sufficient and necessary condition is derived to determine whether the sum of the combinations of Gold functions, tr1n (x2i+1 ), 1≤i ≤n - 1, over finite fields F2n (n be even) in addition to another term tr1n/2 (x2n/2+1 ) is a Bent function. Similar to the result presented by Khoo et al., the condition can be verified by polynominal greatest common divisor (GCD) computation.A similar result also holds in the case Fpn ( n be even, p be odd prime). Using the constructed Bent functions and Niho type Bent functions given by Dobbertin et al., many new generalized binary Bent sequences are obtained.
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Impact of polarization mode dispersion and nonlinear effect on 40 Gbit/s dense wavelength division multiplexing system
SUN Xue-ming, ZHANG Hui-jian, ZUO Meng, GU Wan-yi, XU Da-xiong
Front. Electr. Electron. Eng.. 2006, 1 (3): 361-366.
https://doi.org/10.1007/s11460-006-0013-4
Dense wavelength division multiplexing (DWDM) system is the ultimate selection as an optical communication system because of its high speeds and capacities. However, the fiber nonlinear effects and polarization mode dispersion severely limit the performance of the system when signal propagates at 40 Gbit/s in a single channel. The coupled nonlinear Schröinger equations of a single channel in DWDM, which are all considered factors of group velocity dispersion (GVD), self phase modulation (SPM), cross phase modulation (XPM), four wave mixing (FWM) and polarization mode dispersion (PMD), are derived, while their number results are obtained with extended split-step Fourier method. Finally, to analyze the impacts of the fiber nonlinear effects and PMD on the optical communication system, the simulated results of an 8×40 Gbit/s DWDM system are discussed under different conditions respectively.
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23 articles
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