• Title/Summary/Keyword: inter-symbol interference (ISI)

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The Effect of Partial Response Signaling Pulses under Wireless Communication Environments

  • Park, Won-Ho;Kong, Hyung-Yun
    • Proceedings of the IEEK Conference
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    • 1999.06a
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    • pp.57-60
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    • 1999
  • In many radio communication environments, there is a special component, called inter-symbol interference (ISI), mused by multipath time delay of signal and ISI components impose limitation of the data transmission rate. In this paper, we consider signaling pulse shapes, called partial response signaling (PRS), for minimizing the effect of ISI and show the improvement of performance by applying one of the partial-response signaling (PRS) pulses to two types of receiver system under dependent noise environments through the Monte-Carlo computer simulations.

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A Resource Management Technique for OFDM-based Digital Duplex Systems (OFDM 기반의 디지털 이중화 시스템을 위한 자원 관리 기법)

  • Park, Chang-Hwan;Kim, Moo-Chul;Ko, Yo-Han;Park, Kyung-Won;Jeon, Won-Gi;Paik, Jong-Ho;Lee, Seok-Pil;Cho, Yong-Soo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.12C
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    • pp.1131-1137
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    • 2009
  • In this paper, a resource management technique for digital duplexing (DD) systems using orthogonal frequency division multiple access (OFDMA) is proposed. The proposed technique can reduce the dynamic range of the signal received at the subscriber station (SS) and minimize the effects of inter-symbol interference (ISI) and inter-carrier interference (ICI) due to the time difference of arrival (TDoA) without using a cyclic suffix. It is shown by computer simulation that the proposed technique can reduce the number of bits for an analog-to-digital converter (ADC) and increase the signal-to-interference and noise ratio (SINR) significantly.

DOA(Direction of Arrival) Estimation based Beamforming technique for VBeam Reception Performance Enhancement (VBeam 수신 성능 개선을 위한 입사각 추정 기반의 빔형성 알고리즘 연구)

  • Lee, Jae-Eun;Shim, Tae-Bo
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.47 no.5
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    • pp.212-221
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    • 2010
  • The bubbles could be created from multiple source in the surface of ocean. The bubbles which are created like this affect to the intensity and the sound speed of acoustic wave which are used from the ocean. From the research, it observed Reverberation from the sea surface, using Vbeam transmission and reception equipment that was a cross-shaped Array, from 2008 July 2nd to July 3rd at 4Km from the East Sea Mookho port. It is difficult to analyze data because the received signal has ambient noise and occurrence ISI(Inter Symbol Interference) for multipath. This paper remove that ambient noise and ISI using the directions of arrival beamforming and the filter and sum beamforming. After beamforming, a following DFE(Decision Feedback Equalizer) removes the remaining multipath components. Experimental results show that the proposed technique reduce the errors caused by ISI.

Performance Comparison of OFDM and FMT Systems under Jamming Environment (재밍 환경 하에서 OFDM과 FMT 시스템의 성능 비교)

  • Kim, Jong-Mann
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.2
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    • pp.100-106
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    • 2007
  • In this paper, the performance of OFDM(Orthogonal Frequency Division Multiplexing) and FMT(Filtered Multi-tone) Systems is compared under jamming environment. Two systems are multi-carrier systems to improve data rates. Through the comparison of two systems under jamming environment, the characteristics and strong/weak points of each system are analyzed.

Effect Investigation of a GP for Asynchronous MC-CDMA Systems (비동기 MC-CDMA 시스템에 대한 보호구간의 영향 분석)

  • Ko, Kyun-Byoung;Hong, Dae-Sik
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.11C
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    • pp.851-859
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    • 2008
  • This paper investigates the effect a guard period (GP) in the form of a cyclic prefix for asynchronous multicarrier-code division multiple access (MC-CDMA) systems. At first, we analyze the performance of asynchronous MC-CDMA systems with a GP, which results in closed-form bit error rate (BER) performance. Furthermore, it confirms that the frequency diversity of MC-CDMA systems is identical to the path diversity. The analytical approach proposed here is extended to the case without a GP. The derived analytical results show that a GP is required for MC-CDMA systems in order to mitigate not only the effect of intersymbol interference (ISI) and intercarrier interference (ICI) but also the desired signal power degradation. In addition, the accuracy of the proposed analysis is verified by simulations.

A Two-Dimensional Code for Bit Patterned Magnetic Recording Channel (비트 패턴 자기기록 채널을 위한 2차원 변조부호)

  • Kim, Gukhui;Lee, Jaejin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.9
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    • pp.739-743
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    • 2013
  • In this paper, a two-dimensional (2-D) channel code for magnetic patterned media is proposed. Patterned media records an information bit on a magnetized dot. Since the space between adjacent tracks is narrow in order to increase the storage density, inter-track interference (ITI) and inter-symbol interference (ISI) can be problems. The amplitude of a bit signal can be corrupted by the 2-D ISI. The signal of the bit surrounded by the same value can be especially destructive, i.e. when its value is the same as the values of the eight surrounding bits. The proposed modulation coding scheme improves the decoding performance of patterned media by preventing this worst case and provides a better code rate than conventional channel codes.

A Signal Detection Technique for OFDMA-based Wireless Mesh Networks with Different Time Delays (서로 다른 지연 시간을 갖는 OFDMA 기반의 Wireless Mesh Networks를 위한 신호 검출 기법)

  • Park, Chang-Hwan;Yoo, Hyun-Il;Kim, Yeong-Jun;Kwon, Dong-Seung;Cho, Yong-Soo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.6C
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    • pp.495-505
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    • 2010
  • In this paper, the effect of Near-Far Problem (NFP) among distributed nodes in OFDMA-based Wireless Mesh Networks (WMNs) is analyzed by investigating statistical characteristics of Time Difference of Arrival (TDoA) and Desired-to-Undesired power Ratio (DUR). In order to overcome the effects of Inter-Symbol Interference (ISI), Inter-Carrier Interference (ICI), and Inter Link Interference (ILI), caused by TDoA in WMNs, we derive effective SINR for each subcarrier, and then, propose the optimal starting point of FFT window which can minimize BER for each subcarrier. In addition, we propose a subcarrier-based Zero Forcing - 2 Dimensional Ordered Successive Interference Cancellation (ZF-2DOSIC) technique for signal detection in WMNs with TDoA. It is verified by simulation that the effective SINR and uncoded BER performances of the proposed signal detection technique for OFDMA-based WMNs are significantly improved, compared with those of conventional technique.

Performance Improvement Technique for an OFDM System without Guard Interval (보호구간이 없는 OFDM 시스템을 위한 성능 향상 기법)

  • Kim Sung-Hoon;Park Joong-Hoo;Choi Gin-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.5A
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    • pp.382-388
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    • 2005
  • An OFDM system may be a good candidate for a next-generation wireless communication system which requires high-speed and high-rate data transmission. In OFDM systems, guard intervals are inserted to mitigate the effects of ISI (Inter-Symbol Interference). But guard interval insertion degrades the system performance from the standpoint of data rate and bandwidth efficiency. In this paper, a new method to improve the performance of an OFDM system without guard interval. First, PIC (Parallel Interference Cancellation) scheme which can reduce ISI by subtracting the estimated multi-path components from the received signal will be considered. And the proposed system with Pseudo-Decorrelator estimates transmitted signals by using the inverse matrix of cross-correlation matrix relating to interference components. The performance of the proposed system is evaluated through computer simulations and compared with that of the PIC system and an OFDM system without guard interval.

Cyclic Prefix Reconstruction and Equalization for EST based Modulation (EST기반 변조에서 Cyclic Prefix 복원 및 등화기법)

  • Kwun, Soon-Ik;Kwon, Byung-Uk;Hwang, Tea-Won
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.9A
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    • pp.835-843
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    • 2010
  • Energy spreading transform (EST) based equalization is a very effective technique to remove inter symbol interference (ISI) in frequency selective channel. EST based system uses cyclic prefix (CP) similar to orthogonal frequency division multiplexing (OFDM) system. Since CP is a redundancy, it degrades the data transmission rate. RISIC is an algorithm that removes an inter block interference (IBI) caused by insufficient CP length and reconstructs CP. In this paper, we propose a system that combines the existing EST system with quadrature phase shift keying (QPSK) modulation and RISIC algorithm to enhance the efficiency of the transmission. Also we extend the proposed system to 16 quadrature amplitude modulation (QAM) modulation. The proposed system is shown to performance close to matched filter bound (MFB) even with insufficient CP.

Cooperative Communications Based on Virtual MIMO Transmission for Vehicles (네트워크 코딩을 활용한 가상 다중 안테나 시스템 기반 차량용 협력 통신 기술)

  • Kim, Ilhwan;Kim, Junghyun;Ji, Soonbae;You, Cheolwoo
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.4
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    • pp.17-22
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    • 2015
  • In this paper, we propose a cooperative vehicle communication scheme for high transmission efficiency and coverage extension under multipath fading environment of moving vehicle networks. The proposed scheme uses a Network coding scheme for improvement of receiving performance by using virtual Multiple-Input Multiple-Output(MIMO) transmit diversity. Simulation results have shown that the proposed scheme also provides alleviated Inter Symbol Interference(ISI) and Inter Channel Interference(ICI) as well as Signal-to-Noise Ratio(SNR) improvement and improve 3dB compared to the conventional scheme, since it can utilize the good properties of spatial diversity and coding gain by using virtual MIMO configuration. In this paper, we propose simulations of Ultra-Wideband(UWB) communication system to show validity by using the MATLAB.