• Title/Summary/Keyword: Interference error

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Radial Contact Force Measurement of Lip Seals with a Split Shaft Device (스플릿트샤프트 장치를 이용한 립실의 접촉력측정)

  • Kim, Wan-Doo
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1996.10a
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    • pp.158-162
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    • 1996
  • A split shaft device is commonly used to measure the radial force of lip seals. The radial force measured with this device includes some inevitable error. This error is caused by the fact that the split shafts cannot maintain a perfect circle when the interference becomes larger or smaller than some initial interference. In this study, a theoretical model for the calculation of the radial contact force has been carried out, and an explicit equation for the measurement error as a function of the initial interference and the interference to be measured has been obtained. The error when the interference is small is not dependent upon the material properties and the shape of the lip seal, but rather upon the amplitude of the initial interference and the interference to be measured. When the interference is larger or smaller than the initial interference, the measured contact force is always underestimated or overestimated.

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Low-Complexity MIMO Detection Algorithm with Adaptive Interference Mitigation in DL MU-MIMO Systems with Quantization Error

  • Park, Jangyong;Kim, Minjoon;Kim, Hyunsub;Jung, Yunho;Kim, Jaeseok
    • Journal of Communications and Networks
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    • v.18 no.2
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    • pp.210-217
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    • 2016
  • In this paper, we propose a low complexity multiple-input multiple-output (MIMO) detection algorithm with adaptive interference mitigation in downlink multiuser MIMO (DL MU-MIMO) systems with quantization error of the channel state information (CSI) feedback. In DL MU-MIMO systems using the imperfect precoding matrix caused by quantization error of the CSI feedback, the station receives the desired signal as well as the residual interference signal. Therefore, a complexMIMO detection algorithm with interference mitigation is required for mitigating the residual interference. To reduce the computational complexity, we propose a MIMO detection algorithm with adaptive interference mitigation. The proposed algorithm adaptively mitigates the residual interference by using the maximum likelihood detection (MLD) error criterion (MEC). We derive a theoretical MEC by using the MLD error condition and a practical MEC by approximating the theoretical MEC. In conclusion, the proposed algorithm adaptively performs interference mitigation when satisfying the practical MEC. Simulation results show that the proposed algorithm reduces the computational complexity and has the same performance, compared to the generalized sphere decoder, which always performs interference mitigation.

Cognitive Relay Networks with Underlay Spectrum Sharing and Channel Estimation Error: Interference Probability and BER Analysis

  • Ho-Van, Khuong
    • Journal of Communications and Networks
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    • v.16 no.3
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    • pp.301-304
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    • 2014
  • This paper proposes accurate interference probability and bit error rate formulas for cognitive relay networks with underlay spectrum sharing and channel estimation error (CEE). Numerous results reveal that the CEE not only degrades the performance of secondary systems (SSs) but also increases interference power caused by SSs to primary systems (PSs), eventually unfavorable to both systems. A solution to further protect PSs from this effect through reducing the power of secondary transmitters is investigated and analyzed.

Error-detection-coding-aided iterative hard decision interference cancellation for MIMO systems with HARQ

  • Park, Sangjoon
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.3
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    • pp.1016-1030
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    • 2018
  • In this paper, an error-detection-coding-aided iterative hard decision interference cancellation (EDC-IHIC) scheme for multiple-input multiple-output systems employing hybrid automatic repeat request (HARQ) for multi-packet transmission is developed and investigated. In the EDC-IHIC scheme, only packets identified as error-free by the EDC are submitted to the interference cancellation (IC) stage for cancellation from the received signals. Therefore, the possibility of error propagation, including inter-transmission error propagation, can be eliminated using EDC-IHIC. Because EDC must be implemented in systems that employ HARQ to determine packet retransmission, error propagation can be prevented without the need for additional redundancy. The results of simulations conducted herein verify that the EDC-IHIC scheme outperforms conventional hard decision IC schemes in terms of the packet error rate in various environments.

Performance Enhancement Technique in Visible Light Communication System for Smart Building (스마트 빌딩을 위한 가시광 통신 시스템의 성능 향상 기법)

  • Seo, Sung-Il
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.20 no.5
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    • pp.39-43
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    • 2020
  • In this paper, we propose the multi-channel interference cancellation algorithm for visible light communication (VLC) in smart building. The VLC system is communication technology using visible rays that come out in Light Emitting Diode (LED) device. It has energy curtailment effect and possible to use in ubiquitous network service applications. When a large number of users communicate indoors, the performance can be reduced due to channel interference. To remove interference, at the first, the minimum mean square error (MMSE) scheme as interference cancellation methods used, and then the successive interference cancellation (SIC) is applied to obtain additional diversity gain and improve interference cancellation performance. Indoor VLC channel model is employed. The performance is evaluated in terms of bit error rate (BER). From the simulation results, it is confirmed that the proposed scheme has better BER performance compared to the previous systems. As a result, the proposed interference cancellation improves the signal quality of VLC systems by effectively removing the channel noise. The results of the paper can be applied to VLC for smart building and general communication systems.

Error Performance Analysis of Digital Radio Signals in an Electromagnetic Interference (EMI) Environment of Impulsive Noise Plus Disturbance (임펄스 잡음과 방해파에 의한 전자파 장해(EMI) 환경하에서의 디지털 무선통신 신호의 오율해석)

  • Cho, Sung-Eon;Leem, Kill-Yong;Cho, Sung-Joon;Lee, Jin
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.6 no.3
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    • pp.36-54
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    • 1995
  • The error performance of digital radio signals (i.e., M-ary PSK signal, DQPSK signal, MSK signal, GMSK signal) interfered by impulsive noise and electromagnetic interference (EMI) is analyzed and discussed. In analysis at first, the error rate equations have been derived in an electromagnetic interference plus impulsive noise environment. And then, the error performance has been evaluated and shown in figures as a function of carrier-to-noise ratio, carrier-to-interference ratio, impu- lsive index, gaussian noise to impulsive noise power ratio, and interference index to measure the amount of error degradation in digital radio signals. From the obtained results we have known that in the presence of m-distributed tone interference plus inpulsive noise, the more significant the electromagnetic interference amplitude varies, the more significant performance degradation is produced. The listing the digital radio signals from the most degraded to the least is that DQPSK, GMSK, QPSK and MSK signal. In the constant amplitude tone interference plus impulsive noise environment, the effect of in- terference nearly disappears over about 20dB in CIR. The effect of constant tone interference on error rate performance is reduced more remarkably in the region from 10dB to 15dB in CIR. In both enviroments of m-distributed tone interference and constant amplitude tone interference, the more electromagnetic interference amplitude varies and CIR increases, the more error perfor- mance is improved. But it is found out that the performance can not be improved significantly even the electromagnetic interference becomes weak. This describes that the impulsive noise affects dominantly to the performance degradation.

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A New In-band Full-duplex SIC Scheme Using a Phase Rotator

  • Lee, Haesoon;Kim, Dongkyu;Kim, Jinmin;Hong, Daesik
    • IEIE Transactions on Smart Processing and Computing
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    • v.3 no.4
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    • pp.240-245
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    • 2014
  • How well the self-interference cancellation (SIC) technique performs is a primary issue in realizing an in-band full-duplex (FD) wireless communication system. One factor affecting its performance is channel estimation error on the self-interference channel. We propose a new analog SIC scheme which is robust to channel estimation error. It uses phase rotators in the radio frequency (RF) chain. We also derive closed-form equations for the residual self-interference of the proposed and the conventional schemes. The analytical and numerical results show that the residual self-interference under the proposed SIC scheme is less than that using the conventional scheme, even though channel estimation error is present.

A Study on the Incident Angle Estimation Method of Target at Coherent Interference (상관성 간섭에서 표적의 입사각 추정 방법에 대한 연구)

  • Shin, Ho-Sub
    • Journal of the Korea Society of Computer and Information
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    • v.15 no.5
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    • pp.75-81
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    • 2010
  • Adaptive array antenna system estimates target signal, as making a null pattern toward the interference signal. However, receiving a coherent interference signal at adaptive array antenna system, as target signal is regarded as interference signal, the performance of system rapidly decreases. The main beam does not direct an incidence direction of target signal due to sensitivity in directivity error. This paper proposes beamforming algorithm which combines high order limit condition and directivity error modify method. And it minimizes degree of freedom and decreases interference signal and directivity error using proposed algorithm. This paper compares and analyzes the performance of proposed algorithm and general algorithm using simulation. In this paper, the proposed algorithm correctly estimates an incident angle, but general algorithm occurs an error of about $0.8^{\circ}$.

Error Rate Performance of FH/MFSK Signal with Partial-Band Interference in m-distribution Fading Environment (m-분포 페이딩 환경하에서 부분대역 간섭을 받는 FH/MFSK신호의 오율특성)

  • 강희조;조성준
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.11
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    • pp.1320-1331
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    • 1992
  • The error rate equation of FH/MFSK signal of repeated diversity received over m-distribution fading channel with partial-band interference has been derived and the error rate has been evaluated to show in figures as a function of signal to noise ratio, signal to interference ratio, fading figure, repeated number, partial-band interference fraction and power correlation coefficient between signal and interference. In this paper, we assumed that repeated diversity technique is used in transmitter against fading occurred in mobile radio channel. By comparing the error rate performance in diversity against fading and the obtainable degree of improvement of error performance with diversity technique has been found out. From the result, it is known that error rate performance deteriorates more as $\rho$ becomes small i.e., the partial-band interference gives more effect on error performance than full-band interference. Also when the values of $E_b/N_1$ and $\rho$ are small. as depth of fading diversity technique.

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Non-Orthogonal Multiple Access (NOMA) to Enhance Capacity in 5G

  • Lim, Sungmook;Ko, Kyunbyoung
    • International Journal of Contents
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    • v.11 no.4
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    • pp.38-43
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    • 2015
  • Non-orthogonal multiple access (NOMA) where all users share the entire time and frequency resource has paid attention as one of the key technologies to enhance the spectral efficiency and the total throughput. Nevertheless, as the number of users and SIC error increase, the inter-user interference and the residual interference due to the SIC error also increase, resulting in performance degradation. In order to mitigate the performance degradation, we propose grouping-based NOMA system. In the proposed scheme, all users are divided into two groups based on the distance between the BS and each user, where one utilizes the first half of the bandwidth and the other utilizes the rest in the orthogonal manner. On the other hand, users in each group share the spectrum in the non-orthogonal manner. Grouping users can reduce both the inter-user interference and residual interference due to the SIC error, so it can outperform conventional NOMA system, especially in case that the number of users and the SIC error increase. Based on that, we also present the hybrid operation of the conventional and the proposed NOMA systems. In numerical results, the total throughput of the proposed NOMA systems is compared with that of the conventional NOMA systems with regard to the number of users and SIC error. It is confirmed that the proposed NOMA system outperforms the conventional NOMA system as the number of users and the SIC error increase.