• Title/Summary/Keyword: Interference reduction

Search Result 444, Processing Time 0.039 seconds

A Channel Estimation Method for Multipath Feedback Interference Signal Cancellation of RF Repeaters (RF 중계기의 다중 궤환 간섭 신호 제거를 위한 채널 추정 방식)

  • Lee, Sang-Dae;Park, Jin;Sung, Won-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.2A
    • /
    • pp.98-106
    • /
    • 2008
  • To reduce the outage probability and to increase the transmission capacity, the importance of repeaters in cellular systems keeps increasing. Unlike optical repeaters which require wireline connections, RF repeaters are easy to install, have low limitations in location and also have a reduced operational expense such as the optical fiber maintenance cost. On the other hand, RF repeaters suffer the interference due to the feedback signals between the transmitter and receiver antennas, hence require an extra interference cancellation method when the amount of the feedback signal reduction by using the shielding is not sufficient. In this paper, a channel estimation method for two-path feedback interference signals in the ICS (Interference Cancellation System) repeaters using baseband signal processing is proposed and its performance is evaluated. When compared with the conventional method which estimates each multipath individually, the proposed method achieves 10 dB performance gain in terms of the normalized mean-squared-error.

Joint Lattice-Reduction-Aided Precoder Design for Multiuser MIMO Relay System

  • Jiang, Hua;Cheng, Hao;Shen, Lizhen;Liu, Guoqing
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.10 no.7
    • /
    • pp.3010-3025
    • /
    • 2016
  • Lattice reduction (LR) has been used widely in conventional multiple-input multiple-output (MIMO) systems to enhance the performance. However, LR is hard to be applied to the relay systems which are important but more complicated in the wireless communication theory. This paper introduces a new viewpoint for utilizing LR in multiuser MIMO relay systems. The vector precoding (VP) is designed along with zero force (ZF) criterion and minimum mean square error (MMSE) criterion and enhanced by LR algorithm. This implementable precoder design combines nonlinear processing at the base station (BS) and linear processing at the relay. This precoder is capable of avoiding multiuser interference (MUI) at the mobile stations (MSs) and achieving excellent performance. Moreover, it is shown that the amount of feedback information is much less than that of the singular value decomposition (SVD) design. Simulation results show that the proposed scheme using the complex version of the Lenstra--Lenstra--Lovász (LLL) algorithm significantly improves system performance.

Identifying Dynamic Characteristics of the Traction Motor Housing For the Noise reduction of the Electric vehicle (전기자동차 소음저감을 위한 구동모터 하우징의 동특성 평가)

  • Park, Jongchan;Park, Seungyong;Cho, Hyun-Kyu;Park, Yunsu
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2012.10a
    • /
    • pp.818-823
    • /
    • 2012
  • Assessment of the dynamics properties, like damping, dynamic stiffness and resonance sharpness is essential for the development of a robust system, specifically for the reduction of a traction motor noise. A practical method for identifying dynamic characteristics of a traction motor hosing for an electric vehicle is proposed. Assembling using interference fit of the components of the motor is attributed to the main cause of strong nonlinearity. It is well known that nonlinearity of a structure makes it difficult to assess damping properties or dynamic characteristics of the system. This research presents a practical damping or dynamic stiffness identifying procedures for a nonlinear system according to the boundary condition between assembled components. Based on the simple idea that impact forces of modal tests are highly affected on the condition of the hammer tip, Auto Power Spectrum of the impact forces are used to assess the assembling condition and dynamic characteristics of the system, especially, damping of the system.

  • PDF

A Study on Vehicle-based Durability Evaluation for Weight-reduced Valve Parts of the Dual Clutch Transmission

  • ChanEun Kim;TaeWook Kim
    • Tribology and Lubricants
    • /
    • v.40 no.1
    • /
    • pp.24-27
    • /
    • 2024
  • A monotype valve body for a dual clutch transmission has the potential to reduce costs, weight, and manufacturing time by modularizing various parts, including those of existing solenoid packs and valve bodies, into one through the application of super-precision die casting technology. However, this approach may lead to challenges such as reduced rigidity and increased interference due to modularization and compactness, impacting both product performance due to the reduced weight as well as durability and reliability. Unlike existing products, this approach requires a high-precision thin-wall block to avoid more complicated flow line formation, interference between flow lines, and leaks, as well as a strict quality requirement standard and precise inspections including detection of internal defects. To conduct precise inspections, we built an equivalent model corresponding to a driving distance of 300,000 km. Testing involved simulating actual road loads using a real vehicle and a chassis dynamometer in the FTP-75 mode (EPA Federal Test Procedure). The aim of the study was to establish a vehicle load-based part durability model for manufacturing a mono-type valve body and to develop fundamental technology for part weight reduction through preliminary design by introducing analytical weight reduction technology based on the derived results.

A Study on Inter Band Interference and PAPR Reduction in Multi-Cell System based on OFDM Techniques (OFDM 기법에 기반한 Multi-Cell 시스템에서 PAPR 감소와 대역간 간섭에 관한 연구)

  • Kim, Wan-Tae;Yoo, Sun-Yong;Jo, Sung-Joon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • 2008.10a
    • /
    • pp.693-696
    • /
    • 2008
  • The systems for mobile communication services of fourth generation use OFDM (Orthogonal Frequency Division Multiplexing) scheme that ran transmit large amounts of data to support the multimedia services, and consist of several types of cell, such as Macro Cell, Pico Cell, Femto Cell to improve the qualify of service. According to subdivision of communication region, superposition of cells in co-channel different from conventional single cell is used, but it cause inter band interference between systems. In particular, an OFDM signal consists of a number of independently modulated subcarriers, and superposition of these subcarriers causes a problem that ran give a large PAPR. Increased PAPR induces signal distortion passing through components such as power amplifier so that inter band interference is caused by out-of-band spectrum radiation. In order to minimize the inter band interference, this paper applies PAPR reduction scheme and analyzes the out-of-band spectrum radiation when the signal passes through nonlinear components such an power amplifier.

  • PDF

Vibration Signal Analysis of Running Electric Train using Adaptive Signal Processing (적응신호처리에 의한 주행전기동차의 진동신호해석)

  • 최연선
    • Journal of the Korean Society for Railway
    • /
    • v.2 no.2
    • /
    • pp.13-20
    • /
    • 1999
  • The vibration signals of driving parts of electric train are distorted its signal patterns due to the impact components, which occurs when wheel passes rail joints. An elimination method of the impact components is investigated using adaptive signal processing technique in this study The result shows that adaptive interference canceling method seems to be more effective than line enhancement technique. The application of adaptive interference canceling method to the signal measured at bogie shows that the extractions of the signals of driving parts of traction motor, reduction gear, and axle bearing are successful. Therefore, only the signals of bogie, which is the place to attach an accelerometer easily, is sufficient for the fault diagnosis and the safety evaluation of electric train. Also, adaptive interference canceling method can be applicable to evaluate the performance of vibration isolation between bogie and car body and to investigate the characteristics of indoor sound.

  • PDF

Electromagnetic Interference Analysis of an Inhomogeneous Electromagnetic Bandgap Power Bus for High-Speed Circuits

  • Cho, Jonghyun;Kim, Myunghoi
    • Journal of information and communication convergence engineering
    • /
    • v.15 no.4
    • /
    • pp.237-243
    • /
    • 2017
  • This paper presents an analysis of the electromagnetic interference of a heterogeneous power bus where electromagnetic bandgap (EBG) cells are irregularly arranged. To mitigate electrical-noise coupling between high-speed circuits, the EBG structure is placed between parallel plate waveguide (PPW)-based power buses on which the noise source and victim circuits are mounted. We examine a noise suppression characteristic of the heterogeneous power bus in terms of scattering parameters. The characteristics of the dispersion and scattering parameters are compared in the sensitivity analysis of the EBG structure. Electric field distributions at significant frequencies are thoroughly examined using electromagnetic simulation based on a finite element method (FEM). The noise suppression characteristics of the heterogeneous power bus are demonstrated experimentally. The heterogeneous power bus achieves significant reduction of electrical-noise coupling compared to the homogeneous power buses that are adopted in conventional high-speed circuit design. In addition, the measurements show good agreement with the FEM simulation results.

Application of artificial neural network for determination of wind induced pressures on gable roof

  • Kwatra, Naveen;Godbole, P.N.;Krishna, Prem
    • Wind and Structures
    • /
    • v.5 no.1
    • /
    • pp.1-14
    • /
    • 2002
  • Artificial Neural Networks (ANN) have the capability to develop functional relationships between input-output patterns obtained from any source. Thus ANN can be conveniently used to develop a generalised relationship from limited and sometimes inconsistent data, and can therefore also be applied to tackle the data obtained from wind tunnel tests on building models with large number of variables. In this paper ANN model has been developed for predicting wind induced pressures in various zones of a Gable Building from limited test data. The procedure is also extended to a case wherein interference effects on a gable roof building by a similar building are studied. It is found that the Artificial Neural Network modelling is seen to predict successfully, the pressure coefficients for any roof slope that has not been covered by the experimental study. It is seen that ANN modelling can lead to a reduction of the wind tunnel testing effort for interference studies to almost half.

Vibration Signal Analysis of Running Electric Train using Adaptive Signal Processing (적응신호처리에 의한 주행전기동차의 진동신호해석)

  • 최연선;이봉현
    • Proceedings of the KSR Conference
    • /
    • 1999.05a
    • /
    • pp.143-150
    • /
    • 1999
  • The vibration signals of driving parts of electric train are distorted its signal patterns due to the impact components, which occurs when wheel passes rail joints. An elimination method of the impact components is investigated using adaptive signal processing technique in this study. The result shows that adaptive interference canceling method seems to be more effective than line enhancement technique. The application of adaptive interference canceling method to the signal measured at bogie shows that the extractions of the signals of driving parts of traction motor, reduction gear, and axle bearing are successful. Therefore, only the signals of bogie, which is the place to attach an accelerometer easily, is sufficient for the fault diagnosis and the safety evaluation of electric train. Also, adaptive interference canceling method can be applicable to evaluate the performance of vibration isolation between bogie and car body and to investigate the characteristics of indoor sound.

  • PDF

Interference Device for Noise Reduction of Railway (철도소음 저감을 위한 간섭장치개발)

  • 장강석;심상덕;김영찬;김두훈
    • Proceedings of the KSR Conference
    • /
    • 2000.05a
    • /
    • pp.537-542
    • /
    • 2000
  • When visual intrusion Is an Important factor, it is desirable to find alternative methods of Improving the insertion loss of a noise barrier without Increasing the height. Therefore, the primary object of the work attenuate the noise due to railway by small interference device installed at noise barrier edge. In this paper the performance of noise barriers with attached interference device, in terms of shape, absorptive material and split panel, we examined using the boundary element approach. Also, the scale models are mounted in an anechoic chamber and the frequency of the sound sources are appropriately scaled to simulate full scale site conditions. Lastly, experimental measurements of the designs are executed for a range of frequencies and receiver positions, and are compared with the results of numerical modeling.

  • PDF