http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Gradient-Type Instrumental Variable Method and Its Application to Channel Equalization
Shimamura, Tetsuya,Suzuki, Jouji,Takada, Tomoyuki 대한전자공학회 1994 ISPACS:Intelligent Signal Processing and Communica Vol.1 No.1
In this paper, we present an adaptive IIR equalizer using system identification techniques. Gradient-type instrumental variable(GIV) algorithm is used for the purpose of channel estimation. The proposed equalizer has a cascade structure of an ARMA prefilter and an adaptive FIR equalizer. The ARMA prefilter is designed based on the transfer function estimated by the GIV algorithm. The ARMA prefiltering leads to reduction in a degree of correlation of the channel output. The LMS algorithm of the cascaded FIR adaptive equalizer provides faster convergence and smaller residual errors than the commonly used adaptive FIR equalizer. Simulation results are shown to confirm the performance of the proposed adaptive IIR equalizer.
Nonlinear Characteristics of DFT-Spread WR-OFDM System for Spectrum-efficient Communications
Md. Najmul Hossain,Tetsuya Shimamura,Heung-Gyoon Ryu 대한전자공학회 2019 IEIE Transactions on Smart Processing & Computing Vol.8 No.6
Since frequency resources are limited, and power saving is also a vital issue, a more spectrum-efficient and power-saving communications system design is the most important research goal. In this paper, we propose an improved, spectrally efficient new discrete Fourier transform (DFT)-Spread Windowing and Restructuring (WR)-Orthogonal Frequency Division Multiplexing (DFT-Spread WR-OFDM) communications system, in thought of various strengths of high-power amplifier (HPA) nonlinearity for a reasonably allowable peak-to-average power ratio (PAPR) and out-of-band (OOB) power emission reduction. Compensation for HPA nonlinearity becomes a difficult task when properly designing efficient multicarrier schemes and fifth generation (5G)-beyond 5G candidate waveforms for cellular wireless communications systems. In practical communications systems, spectral efficiency and power are highly affected by HPA nonlinearity features, and bit error rate (BER) performance also deteriorates. We implemented a time domain window named Tukey (tapered cosine) and localized subcarrier mapping, and the impact of HPA nonlinearity on BER performance and spectral characteristics is comprehensively analyzed. Simulation results demonstrate that the proposed system reduces PAPR and OOB power emissions by 3.176 ㏈ and -81 ㏈, respectively. Additionally, compared to conventional systems, the communication quality of the proposed scheme clearly demonstrates better performance even inHPA nonlinear environments.