• Title/Summary/Keyword: Nonlinearly Amplified Channel

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Performance of 8SQAM System in a Nonlinearly Amplified SCPC-FDMA Channel Interference Environment (비선형 증폭 SCPC-FDMA 채널 간섭 환경에서 8SQAM 시스템의 성능)

  • 성봉훈;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.7C
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    • pp.678-687
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    • 2003
  • 8SQAM(8-state Superposed Quadrature Amplitude Modulation) being a new modem technique for use in power and bandwidth limited digital communication system generates output signals which have a mか and continuous phase transition and a reduced envelope fluctuation by keeping correlation between amplitudes and phases of two subsequent symbols. Also, 8SQAM signal is free of inter-symbol interference(ISI), and has a compact power spectrum. Accordingly 8SQAM, as compared with a conventional 8PSK, is influenced a little by inter-modulation(IM), inter-symbol interference(ISI) and adjacent channel interference(ACI) in a nonlinearly amplified multi-channel(SCPC-FDMA) environment. In this paper, the performance of 8SQAM system in a nonlinearly amplified multi-channel interference environment is analyzed via computer simulation The simulation result shows that 8SQAM outperforms 8PSK with roll-off value of $\alpha$ = 0.3 by 2.7dB in CNR to maintain BER=1$\times$10$^{-4}$ when input back-off(IBO) of HPA is 1dB and channel space is 41.7% of the data bit rate(i.e., spectral efficiency = 2.40b/s/Hz).

A Study on the Performance of DS-CDM-SQAM in Nonlinear Land Mobile Satellite Broadcasting Environments (비선형 육상 이동 위성방송 환경에서 DS-CDM-SQAM의 성능 연구)

  • 김선준;이영진;홍영진;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.5A
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    • pp.537-544
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    • 2004
  • In this paper, we p개pose DS-CDM-SQAM(Superposed Quadrature Amplitude Modulation) which is characterized by its smooth phase transition and small envelope fluctuation, and improves the power efficiency as compared to DS-CDM-QPSK of satellited-based DMB system(ITR-R BO.1130-4 System E) in a nonlinearly amplified channel. Computer simulation results show that the proposed DS-CDM-SQAM improves Eb/No by 1.7㏈ to maintain BER=1${\times}$$10^{-3}$ in nonlinearly amplified multipath mobile radio environments. Therefore, the proposed DS-CDM-SQAM system significantly improves the power efficiency in nonlinear land mobile satellite DMB environments.

Performance of 8SQAM Modem in a Nonlineraly Amplified Multi-Channel Interference Environment (비선형 증폭 다중채널 간섭환경에서의 8SQAM 모뎀 성능)

  • 성봉훈;서종수
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2002.11a
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    • pp.3-8
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    • 2002
  • A new Modem technique - 8-state Superposed QAM(8SQAM) - for use in power and bandwidth limited digital communication system is proposed. The premodulation baseband signal of the 8SQAM system is a double-interval(2Ts) raised cosine pulse superposed with weighted single-interval(Ts) raised cosine pulse. The performance of the 8SQAM, in a nonlinearly amplified multi-channel environment with additive white Gaussian noise(AWGN), inter-symbol interference(ISI), inter-modulation(IM) and adjacent channel interference(ACI), is analyzed via computer simulation. The simulation result shows that the 8SQAM outperforms 8PSK by about 1.6㏈ at BER=$1\times10^{-4}$ when HPA IBO is 1㏈ and channel Spacing, ${\Delta}F$ is 0.417fb.

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Performance of Digital Predistorter in Non-linearly Amplified Land Mobile Satellite Channel (비선형 증폭된 육상이동 위성채널에서 디지털 전왜곡기의 성능)

  • 강우석;이상진;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6B
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    • pp.1042-1047
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    • 1999
  • In this paper, two kinds of digital predistorters are proposed and their performances are analyzed in order to minimize ACI and SNR degradation caused by nonlinearly amplified TC-16QAM signal and to transmit high speed data in power and bandwidth limited land mobile satellite channel. Our simulation results show that LUT predistorter reduces the out-of-band ACI more efficiently as compared to intersymbol interpolated predistorter. Regarding the reduction of in-band SNR and total power intersymbol interpolated predistorter outperforms LUT predistorter. In the simulation mobile satellite channel and nonlinear HPA are modeled by Rician channel and Fujitsu SSPA, respectively.

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Performance of 8SQAM System in a Nonlinearly Amplified Channel Environment (비선형 증폭 채널 환경에서 8SQAM 시스템의 성능)

  • 성봉훈;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.7C
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    • pp.669-677
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    • 2003
  • A new Modem technique - 8SQAM(8-state Superposed Quadrature Amplitude Modulation) - for use in power and bandwidth limited digital communication system is proposed. 8SQAM is free of inter-symbol interference(ISI) and generates output signals which have a smooth and continuous phase transition and a reduced envelope fluctuation by keeping correlation between amplitudes and phases of two subsequent symbols. Accordingly, 8SQAM, as compared with a conventional 8PSK, is influenced a little by ISI and inter-modulation(IM) caused by nonlinear distortions. In this paper, the performance of the 8SQAM system, in a nonlinearly amplified channel impaired by additive white Gaussian noise(AWGN), ISI and IM, is analyzed via computer simulation. The simulation result shows that 8SQAM outperforms 8PSK with roll-off value of $\alpha$=0.25 by 2.5dB in CNR to maintain BER=1$\times$10$^{-4}$ when input back-off(IBO) of HPA is 3dB.

Power Efficient Multi-level Digital Transmission Technique in Non-Linear Mobile Satellite Channel (비선형 이동위성 통신채널에서 전력 효율적 고차 디지털 전송 방식)

  • 이상진;강우석;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.8A
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    • pp.1133-1140
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    • 1999
  • In order to provide high-speed wide-band multimedia services via Low earth(LEO) mobile satellire, power and bandwidth efficient digital transmission technique should to employed. This paper analyzes the performance of Trellis-soded 16QAM and 8PSK-2AM which can transmit twice as much inforemation as QPSK in nonlinearly amplified LEO mobile satellite channel. In the analysis the nonlinear mobile satellite channel is modelled by Rician fading channel amplified by Fujitsu's GaAs FET HPA. Our simulation result shows that 8PSK-2AM is less sensitive to the satellite channel nonlinear distortion and its BER performance is better than that of 16QAM. The BER performance of 8PSK-2AM is further improved by optimizing its signal constellation. Accocordingly it is found that Trellis-coded 8PSK-2AM could provide multimedia services such as Satellite Internet, DBS, DAB and ISDB more efficiently in the power and bandwidth limited mobile satellite channel.

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Performance of CEFSK Systems in Nonlinear Channel Environments (비선형 채널 환경에서 CEFSK 시스템의 성능)

  • Lee, Kee-Hoon;Choi, Byeong-Woo;Shin, Kwan-Ho;Seo, Jong-Soo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.1
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    • pp.79-87
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    • 2013
  • A new modulation technique - correlative encoded FSK (CEFSK) - for use in power and bandwidth limited digital communication system is proposed. CEFSK is free of ISI and generates output signals which have a smooth and continuous phase transition and a reduced envelope fluctuation by keeping correlation between amplitude and phases of two subsequent symbols. In comparison to conventional one-bit differential detected (1DD) GFSK, the performance of the 1DD-CEFSK in a non-linearly amplified (NLA) channel impaired by additive white Gaussian noise (AWGN), ISI and IM, is analyzed via computer simulation. The simulation result shows that, in an NLA single-channel, 1DD-CEFSK provides a signal-to-noise ratio (SNR) advantage of up to 1.2dB and 0.8dB at BER of $1{\times}10^{-4}$ when input back-off (IBO) of HPA is -1.0dB and -3.0dB, respectively. For the same channel environment with multi-channel, 1DD-CEFSK outperforms 1DD-GFSK by 1.1dB in SNR, regardless of the value of IBO.

Compact-SQAM for Power & Bandwidth Algorithm of Output Error Method (전력 및 대역폭 효율적인 디지틀 전송 시스템을 위한 협대역 중첩 직교 변조 방식)

  • 박일근;서종수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.4
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    • pp.519-529
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    • 1993
  • A spectral and power efficient modulation technique, named Compact Superposed Quadrature Amplitude Modulation (Compact-SQAM), is introduced. The performance of Compact-SQAM system, in a Linearly and nonlinearly amplified single and multicarrier environment, in the presence of additive white Gaussian noise(AWGN), intersymbol interference(ISI), timing jitter and adjacent channel interference (ACI), is experimentally analyzed via computer simulation. Various channel conditions, such as channel spacing, between the main and adjacent channels and fade depth on the desired main channel, are examined. Our result shows that Compact-SQAM, and better P(e) performance that other modems using simple Butteroworth type postdetection receive filters. Especially, Compact-SQAM modem achieves higher efficiency of frequency utilization and better P(e) performance than other modems in the severly bandlimited nonlinear multicarrier channels.

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