• Title/Summary/Keyword: Multitone

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An Equalization Method in Filtered Multitone Modulation based on the ISI Estimation (FMT 시스템의 ISI 추정치 기반 등화기법)

  • Ryu, Jung-Hun
    • Journal of Korea Multimedia Society
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    • v.12 no.9
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    • pp.1316-1322
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    • 2009
  • The multicarrier system is in the limelight for broadband wireless communications due to its spectral efficiency. Filtered multitone(FMT) system uses a filter that has several symbol periods duration. Using long-period filter causes a performance degradation because of intersymbol interference in multipath fading channels. In this paper, we propose a simple equalization method which can reduce the ISI due to the wireless channels. The proposed equalization method compensates the ISI by subtracting the estimated ISI components from the current symbol using one-tap equalizer. The performance of the proposed system is verified through theoretical analysis and simulation results show that the proposed system can mitigate the effect of ISI significantly.

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A Study on the Performance Noncoherent FH/FSK Including Multitone Jamming (멀티톤 재밍을 고려한 비동기 FH/FSK 성능 분석에 관한 연구)

  • Ahn, Jung-Soo;Park, Jin-Soo
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.10
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    • pp.1-9
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    • 1990
  • The performance of noncoherent FH/FSK system in the presence of multitone jamming and noise is analyged. Random and the structured jammings are considered as a multitone jamming model. The probability density function is derived and then optimum decision rule is applied to determine error probability of each cases. As a result, error probabilities of random and structured multitone jamming are shown as a function of number of jamming tones, jamming to signal power ratio, jamming signal phase and one jamming tone power to signal power ratio under Worst-case Jamming interference. It is found that error probability is maximam when one jamming tone power to signal power ratio is 1. Also we know that error performance of random and structured jamming is almost equal.

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Performance of a Multitone CDMA System with Interference Canceller in a Multipath Fading Channel

  • Park, Seung-Keum;Kang, Byeong-Gwon;Chung, Hee-Chang
    • The Journal of the Acoustical Society of Korea
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    • v.17 no.3E
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    • pp.58-66
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    • 1998
  • In this paper, we analyze the effects of interference canceller on the performance of multitone DS/CDMA system proposed by Vandendorpe[5]. There are various kinds of interference canceller suggested by different researchers including parallel and successive cancellers and we adopt a canceller used by Yoon et al.[9] which is a kind of parallel canceller. We consider three kinds of interferences, that is, multipath interference(MPI), interchannel interference(ICI) and multiple access interference(MAI). The ICI is the interference between multitones. The equations for variances. are derived for the inteferences and thermal noise used for signal to noise ratio calculation. We also consider RAKE reception over multipath channel which is modeled as lowpass equivalent linear filter and three stage interference canceller used for performance improvement. We show the performance results for number of canceller stage, diversity order and number of users and draw some conclusions that interference canceller is effective in multitone DS/CDMA system and the performance is further improved with the higher order of diversity and larger number of PN chips.

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Efficient equalizer design for multi-carrier transmission system in local area access (가입자 지역 다중반송파 전송시스템의 등화기 구현)

  • 최재호
    • Journal of the Institute of Convergence Signal Processing
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    • v.2 no.3
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    • pp.32-38
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    • 2001
  • Multi-carrier data transmission system performance is mostly limited by Inter- symbol-interference that is caused by a dispersive characteristic of the transmission channel. In order to enhance the system performance to meet the service requirements of local access, the channel impulse response shortening method incorporated with a channel frequency response compensation method is proposed. For a fast and efficient implementation of the equalizer proposed, Kalman and LMS algorithms are successively used. To verify the channel equalization performance, a set of computer simulation is performed on a filter bank based multitone system operating in a typical high-speed local area data transmission environment. The results showed us a comparable signal-to-interference improvement over the conventional multitone equalization scheme.

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Performance Analysis of BPSK Multitone DS/CDMA System with Interference Canceller (간섭 제거기를 사용한 BPSK 다중 톤 DS/CDMA 시스템의 성능 분석)

  • 박승근;강병권
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.2 no.4
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    • pp.519-529
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    • 1998
  • In this paper, we analyze the effects of interference canceller on the performance of multitone DS/CDMA system. Although there are various kinds of interference cancellers suggested by different researchers, we adopt a canceller used by Yoon et at.[9]. We consider three kinds of inteferences, that is, multiPath interference(MPI), interchannel interference(ICI) and multiple access interference(MPI). The equations for variances ate derived for the inteferences and thermal noise used for signal to noise ratio calculation. We also consider RAKE reception over multipath channel and three stage interference canceller used for performance improvement. We draw some conclusions that interference canceller is effective in multitone DS/CDMA system and the performance is further improved with the higer order of diversity and larger number of PN chips.

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Performance Analysis of FH/MFSK systems with Fading and Multitone Jamming using Time Diversity (페이딩과 멀티톤 재밍하에서 시간 다이버시티를 이용한 FH/MFSK 시스템의 성능 분석)

  • 오영석;조형래;강창언
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.3
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    • pp.260-267
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    • 1992
  • In this paper, the performance of frequency hopped(FH) M-ary frequency shift keyed(MFSK)system is analyzed with the fading channel and the multione famming. In general, the performance degradation of FH/MFSK system is due to the Rayleigh fading and the multitone jamming environment. In order to improve the system performance. the time diversity is used. When the time diversity is applied to the Rayleigh fading and the mulitone jamming, we get around 18dB and 19dB improvements. respectively. And when it is applied to both the Rayleigh fading and the multitone jamming, we get around 4 dB improvement.

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Development of Multitone Jamming Technique Using DDS Core in FPGA (FPGA의 DDS Core를 이용한 다중 톤 재밍 신호 생성)

  • Hong, Sang-Geun;Kwak, Chang-Min;Lee, Wang-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.9
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    • pp.827-832
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    • 2011
  • Communication is very important in warfare. Dispatch riders were used in ancient warfare, but communication system is used in modern warfare, as the advancement of communication equipments. In order to weaken enemy military strength, communication jamming signal disrupts enemy communication systems. Tone jamming is one of the common communication jamming techniques. Tone jamming is that several tones are placed in the spectrum for neutralizing the enemy's radio communication receivers. In this paper, we develop multitone jamming signal controlled tone number up to 10 tones and tone interval between tones using DDS(Direct Digital Synthesizer) core and FPGA(Field Programmable Gate Arry) of Xilinx Inc. and show the jamming signal output.

Efficient Computation of the DFT and IDFT in Communication Systems Using Discrete Multitone Modulation

  • Fertner, Antoni;Hyll, Mattias;Orling, Anders
    • Journal of Communications and Networks
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    • v.1 no.2
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    • pp.86-88
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    • 1999
  • The Discrete Fourier Transform (DFT) and the Inverse Discrete Fourier Transform (IDFT) are commonly used in signal processing applications, in particular in digital communication sys-tems using the multi-carrier modulation principle. In such systems an IDFT is computed at the transmitter end, and a DFT at the re-ceiver end. This paper examines a technique of computations, for which only negligible differences appear between the DFT and the IDFT calculations while the number of arithmetic operations re-quired is substantially reduced. This offers significant advantages for the design of an IDFT/DFT processor for Discrete Multitone(DMT) systems.

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