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        On Narrowband Interference Suppression in OFDM-based Systems with CDMA and Weighted-type Fractional Fourier Transform Domain Preprocessing

        ( Yuan Liang ),( Xinyu Da ),( Shu Wang ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.11

        In this paper, we propose a new scheme to suppress the narrowband interference (NBI) in OFDM-based systems. The scheme utilizes code division multiple access (CDMA) and weighted-type fractional Fourier transform (WFRFT) domain preprocessing technologies. Through setting the WFRFT order, the scheme can switch into a single carrier (SC) or a multi-carrier (MC) frequency division multiple access block transmission system. The residual NBI can be eliminated to the maximum extent when the WFRFT order is selected properly. Final simulation results show that the proposed system can outperform MC and SC with CDMA and frequency domain preprocessing in terms of the narrowband interference suppression.

      • KCI등재

        Modified WFRFT-based Transform Domain Communication System Incorporating with Spectrum Mismatching

        ( Ruiyang Xu ),( Xinyu Da ),( Yuan Liang ),( Hang Hu ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.10

        The transform domain communication system (Hereinafter referred to as TDCS) takes on numerous advantages, inclusive of anti-jamming and low probability of detection. Yet its application is confined by the consistent spectrum in the transmitter and receiver, which is not possible in the case of a huge distance exsits between them. In this paper, a TDCS based modified weighted fractional fourier transform (WFRFT) is proposed to solve the problem resulting from spectrum mismatching for TDCS application. The amplitude and phase information are incorporated with the TDCS signals and transmit to the receiver together in the wake of a modified WFRFT. The basic function and the TDCS signals shall be accessible to the receivers in the wake of an inverse WFRFT transform, which make sure that the original information can be demodulated properly. The system’s reliability while transmitting signals with different modulation methods and with spectrum mismatching is demonstrated by bit error rate (BER). In the meantime, the constellations of the signals and the BER performances at the eavesdropper demonstrate the proposed system is better secured.

      • KCI등재

        Wiretapping Strategies for Artificial Noise Assisted Communication in MU-MIMO wiretap channel

        ( Shu Wang ),( Xinyu Da ),( Zhenyong Chu ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.5

        We investigate the opposite of artificial noise (AN)-assisted communication in multiple-input-multiple-output (MIMO) wiretap channels for the multiuser case by taking the side of the eavesdropper. We first define a framework for an AN-assisted multiuser multiple-input-multiple-output (MU-MIMO) system, for which eavesdropping methods are proposed with and without knowledge of legitimate users` channel state information (CSI). The proposed method without CSI is based on a modified joint approximate diagonalization of eigen-matrices algorithm, which eliminates permutation indetermination and phase ambiguity, as well as the minimum description length algorithm, which blindly estimates the number of secret data sources. Simulation results show that both proposed methods can intercept information effectively. In addition, the proposed method without legitimate users` CSI performs well in terms of robustness and computational complexity.

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        Flow Velocity Deviation of Spinning Solution Under Multi-field Coupling

        Zhiming Zhang,Da Hong,Xinyu Huang,Kang Liu,Qiao Xu,Zhen Chen,Qiaoling Ji,Changjin Ke 한국섬유공학회 2023 Fibers and polymers Vol.24 No.10

        Rotating jet spinning uses the centrifugal force generated by the high-speed rotation of the motor to keep the spinning solution ejected from the nozzle to form nanofibers. At present, the research work on rotating jet spinning mainly involves the materials, properties and applications of fibers, parameter influence and jet trajectory, while there are few studies on the optimization of spinning core components. In this paper, by analyzing the force and flow state of spinning solution in the flow channel of spinning nozzle, it is found that the maximum velocity region of spinning solution will be offset. The reason for this phenomenon is that the spinning solution is subjected to Coriolis force in the rotating system, resulting in the secondary flow of solution. The relationship between nozzle parameters, solution parameters as well as process parameters, and the outlet velocity of solution was sought, and the structure of spinning nozzle was optimized. The factors affecting velocity offset in straight-tube nozzles and bent-tube nozzles are simulated. High-speed centrifugal spinning experiments were conducted using both unoptimized and optimized nozzles.

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