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Adaptive Complex Interpolator for Channel Estimation in Pilot-Aided OFDM System
Guanghui Liu,Liaoyuan Zeng,Hongliang Li,Linfeng Xu,ZhengningWang 한국통신학회 2013 Journal of communications and networks Vol.15 No.5
In an orthogonal frequency division multiplexing system,conventional interpolation techniques cannot correctly balanceperformance and overhead when estimating dynamic longdelaychannels in single frequency networks (SFNs). In this study,classical filter analysis and design methods are employed to derivea complex interpolator for maximizing the resistible echo delay in achannel estimator on the basis of the correlation between frequencydomain interpolating and time domain windowing. The coefficientcomputation of the complex interpolator requires a key parameter,i.e., channel length, which is obtained in the frequency domain witha tentative estimation scheme having low implementation complexity. The proposed complex adaptive interpolator is verified in asimulated digital video broadcasting for terrestrial/handheld receiver. The simulation results indicate that the designed channelestimator can not only handle SFN echoes with more than 200 µsdelay but also achieve a bit-error rate performance close to the optimumminimum mean square error method, which significantlyoutperforms conventional channel estimation methods, while preservinga low implementation cost in a short-delay channel.
Robust CFO Acquisition in PN-Padded OFDM Systems
Guanghui Liu,Liaoyuan Zeng,Hongliang Li,Linfeng Xu,ZhengningWang 한국전자통신연구원 2013 ETRI Journal Vol.35 No.4
As an alternative to the traditional pilot-aided orthogonal frequency division multiplexing (OFDM), the time-domain pseudonoise (PN)-padded OFDM provides a higher spectral efficiency. However, the carrier frequency offset (CFO) attenuates peaks of the conventional PN correlation output, which limits the CFO estimation range of the OFDM synchronizer. An improved correlation is proposed in this letter to remove the CFO-induced amplitude attenuation of correlation peaks. For a synchronizer adopting the designed correlator, a larger range of CFO acquisition is obtained through using wider correlation windows with a smaller interval between them. The proposed method of CFO acquisition is verified in a digital terrestrial multimedia broadcast receiver, in which the synchronizer is able to acquire CFOs up to ±320 kHz in the DVB-T F1 channel. Furthermore, the acquisition range can be expanded in more favorable channels.
Adaptive Complex Interpolator for Channel Estimation in Pilot-Aided OFDM System
Liu, Guanghui,Zeng, Liaoyuan,Li, Hongliang,Xu, Linfeng,Wang, Zhengning The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.5
In an orthogonal frequency division multiplexing system, conventional interpolation techniques cannot correctly balance performance and overhead when estimating dynamic long-delay channels in single frequency networks (SFNs). In this study, classical filter analysis and design methods are employed to derive a complex interpolator for maximizing the resistible echo delay in a channel estimator on the basis of the correlation between frequency domain interpolating and time domain windowing. The coefficient computation of the complex interpolator requires a key parameter, i.e., channel length, which is obtained in the frequency domain with a tentative estimation scheme having low implementation complexity. The proposed complex adaptive interpolator is verified in a simulated digital video broadcasting for terrestrial/handheld receiver. The simulation results indicate that the designed channel estimator can not only handle SFN echoes with more than $200{\mu}s$ delay but also achieve a bit-error rate performance close to the optimum minimum mean square error method, which significantly outperforms conventional channel estimation methods, while preserving a low implementation cost in a short-delay channel.
Effect of SiO2 additives on the microstructure and energy storage density of SrTiO3 ceramics
Guanghui Zhao,Yiqiu Li,Hanxing Liu,Jing Xu,Hua Hao,Minghe Cao,Zhiyong Yu 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3
The compositions of (1-x) SrTiO3-x SiO2 were prepared by a solid-state reaction. The crystalline structure, microstructure and energy storage performance were studied for the purpose of a potential application in high energy density capacitors. Fine grains with an average size of about 400 nm were obtained by adding SiO2 to SrTiO3 ceramics, which leads to a great enhancement in the breakdown performance of the samples. For SiO2-added samples, the notable increase in breakdown strength makes an obvious increase in energy storage density. With 15 vol.% addition, the sample exhibited an average breakdown strength of 36.1 kV/mm, and an energy storage density of 1.155 J/cm3.
Guanghui Qian,Liyan Zhu,Guang Li,Xin Liu,Yiquan Wang 한국유전학회 2015 Genes & Genomics Vol.37 No.4
The Wnt/b-catenin transcriptional activation complex requires the adapter protein Pygopus (Pygo), which links the basal transcription machine to b-catenin to regulate the transcription of target genes. Previous studies revealed that the Pygo genes were broadly involved in the embryonic development of Drosophila, Xenopus and mouse, however, their functions in the embryonic development of amphioxus and zebrafish remain to be investigated. Here, we cloned and characterized one Pygo gene from amphioxus Branchiostoma belcheri (BbPygo) and two fromzebrafish Danio rerio (DrPygo1 and DrPygo2). The spatial–temporal expression profiles showed that all these genes were maternally expressed. BbPygo expression was distributed ubiquitously in the amphioxus embryos before the gastrula stage and became restricted in the pharyngeal region in late stages. Similar to BbPygo, DrPygo2 was also expressed throughout whole embryos before the early gastrula stage, but limited in the pharyngeal region and central nervous system (CNS) in subsequent developing stages. Further knockdown of the DrPygo2 resulted in developmental defects of the body axis, CNS and cartilage segments in zebrafish. In contrast, the expression signal of the DrPygo1 gene was not detectable using the in situ hybridization method, which is consistent with its extremely low expression level detected by RTqPCR. The expression patterns and function investigations revealed in this study suggest that the three Pygo genes probably function differentially though all of them show a conserved maternal expression pattern during the early embryonic stages of amphioxus and zebrafish.
Distinct growth phenomenon observed on L-Arg․ CF3COOH crystals
Xiaojing Liu,Zeyan Wang,Guanghui Zhang,Guangwei Yu,Aidong Duan,Xinqiang Wang,Dong Xu 한국물리학회 2009 Current Applied Physics Vol.9 No.1
Atomic force microscopy has been employed to study the growth behaviour on the {101} facets of L-Arg ․ CF3COOH crystals grown at 25℃ at a supersaturation of σ = 0.2. Nucleation on the wider step terraces and a large nucleus composed of two separate 2D nuclei were observed for the first time. For the region where blocking occurs convex pattern are found in the macrosteps, which correspond to the sites of the impurities that act as pinning points hindering step propagation. Finally, liquid inclusions will be generated because of disparate formation mechanisms. Atomic force microscopy has been employed to study the growth behaviour on the {101} facets of L-Arg ․ CF3COOH crystals grown at 25℃ at a supersaturation of σ = 0.2. Nucleation on the wider step terraces and a large nucleus composed of two separate 2D nuclei were observed for the first time. For the region where blocking occurs convex pattern are found in the macrosteps, which correspond to the sites of the impurities that act as pinning points hindering step propagation. Finally, liquid inclusions will be generated because of disparate formation mechanisms.
CIRCULAR LIST COLORINGS OF SOME GRAPHS
WANG, GUANGHUI,LIU, GUIZHEN,YU, JIGUO 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.20 No.1
The circular list coloring is a circular version of list colorings of graphs. Let $\chi_{c,l}$ denote the circular choosability(or the circular list chromatic number). In this paper, the circular choosability of outer planar graphs and odd wheel is discussed.
Active control of amplitude and phase of high-power RF systems in EAST ICRF heating experiments
Zhu Guanghui,Liu Lunan,Mao Yuzhou,Zhang Xinjun,Guo Yaoyao,Ai Lin,Jiang Runhao,Qin Chengming,Zhang Wei,Yang Hua,Yuan Shuai,Wang Lei,Ju Songqing,Wang Yongsheng,Sun Xuan,Yang Zhida,Wang Jinxin,Cheng Yan 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.2
The EAST ICRF system operating space has been extended in power and phase control with a low-level RF system for the new double-strap antenna. Then the multi-step power and periodic phase scanning experiment were conducted in L-mode plasma, respectively. In the power scanning experiment, the stored energy, radiation power, plasma impedance and the antenna's temperature all have positive responses during the short ramp-ups of PL;ICRF. The core ion temperature increased from 1 keV to 1.5 keV and the core heating area expanded from jZj 5 cmto jZj 10 cm during the injection of ICRF waves. In the phasing scanning experiment, in addition to the same conclusions as the previous relatively phasing scanning experiment, the superposition effect of the fluctuation of stored energy, radiation power and neutron yield caused by phasing change with dual antenna, resulting in the amplitude and phase shift, was also observed. The active control of RF output facilitates the precise control of plasma profiles and greatly benefits future experimental exploration.