• Title/Summary/Keyword: SFH

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Error Probability of a Hybrid DS/SFH Spread-Spectrum System under Tone Jamming (Tone 신호방해 하에서의 DS/SFH 복합 확산대역 시스템의 비트오율)

  • 유병석;이재홍;이상철
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.5
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    • pp.645-655
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    • 1990
  • A hybrid DS/SFH spread spectrum system is used to achieve a larger gain in some applications. The probability of error for a hybrid DS/SFH(direct sequence/slow frequency hopped) spread-spectrum system is calculated over a channel which suffers from multiple-tone jamming and additive white Gaussian noise. BPSK(binary phase shift keying) is considered as modulation scheme. The probability of error is computed for various system parameters such as a DS/SFH hybrid ratio, the number of jamming tones, a jamming-to-signal ratio, and a siganl-to-noise ratio. It is shown that a DS system or a SFH system achieves smaller probability of error than a hybrid DS/SFH system for most values of system parameters. However, it is also shown that there are hybrid ratios with which a hybrid DS/SFH system achieves smaller probability of error than a DS system and a SFH system achieve for some values of system parameters.

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Effects of the Phase Noise in the Frequency Synthesizer on the SFH/M-NCFSK System (주파수 합성기의 위상 잡음이 SFH/M-NCFSK 시스템에 미치는 영향)

  • 손종원;이준서;유흥균;박진수
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.7
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    • pp.685-691
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    • 2003
  • This paper newly analyzes the effect of the phase noise in the frequency synthesizer on the performance of SFH/M-NCFSK system by standard frequency deviation(equation omitted) when noncoherent FSK demodulation of the square-law detector is considered. We derive the SER in the SFH system and analyze the effect of phase noise on the SFH/M-NCFSK system performance according to the hopping frequency spacing (1/T$\_$h/) and the variation of the standard frequency deviation (equation omitted). The required SNR is about 13.4 dB to meet Ps=10$\^$-3/ when the standard frequency deviation is about 4.0 Hz and the hopping frequency spacing (1/T$\_$h/) in the SFH/2-NCFSK system is 30. So, there is about 2.4 dB power penalty than the phase noise-free system. If the hopping frequency spacing 1/T$\_$h/ is under 30, the error floor may happen and SER considerably grows up. We show that the analytic results closely match with the simulation results.

Performance Comparison of the OFDM/SFH and OFDM/DS Systems in the Jamming Channel (OFDM/SFH와 OFDM/DS 시스템의 Jamming 채널에서 성능비교)

  • 박종현;김상우;유흥균;이상태
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.11
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    • pp.1149-1155
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    • 2003
  • OFDM/SFH(orthogonal frequency division multiplexing/slow frequency hopping) system is the combination of OFDM communication system with frequency hopping(FH) method and OFDM/DS(orthogonal frequency division multiplexing/direct sequence) system combines the OFDM communication system with direct sequence(DS) method in terms of PN(pseudo noise) sequence. These two systems are also can be used for anti-jamming. In this study we analyze performances of OFDM/SFH system and OFDM/DS system with the equal information rate in partial band jamming and tone jamming channel. We find BER(bit error rate) in the variation of JFR(jamming fractional ratio) and JSR(jamming to signal power ratio) of the partial band jamming. Also, BER is found in the several JSR of the single tone or multi tone jamming. OFDM/DS system shows better performance than OFDM/SFH system in partial band jamming environment. OFDM/DS system has about 2.5 ㏈ SNR(signal to noise power ratio) gains than OFDM/SFH system when JFR=4/16 and JSR=0 ㏈ to meet BER=10$\^$-3/. However, OFDM/SFH system has about 3 ㏈ SNR gains than OFDM/DS system at single tone jamming of JSR=5 ㏈. In multi tone jamming, performance of OFDM/SFH system is considerably degraded than OFDM/DS system.

Performance Analysis of Hybrid DS/SFH Spread Spectrum System using BFSK Modulations over Nakagami-m Fading Channel with Multitone Jamming (다중톤 재밍이 존재하는 나카가미-­m 페이딩 환경에서 BFSK 변조방식을 이용한 Hybrid DS/SFH 확산대역 시스템의 성능분석)

  • 정근열;박진수
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.8
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    • pp.1629-1637
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    • 2003
  • In this paper, we analyzed the performance of a hybird DS/SFH(Direct­Sequency­Slow Frequency­Hopping) Spread Spectrum system with BFSK modulation over Nakagami­m fading channel with multitone jamming. The performance of the system was improved when a frequency bowing rate increased. In case that process gain of hybrid DS/SFH Spread Spectrum system to be fixed, the hybrid DS/SFH Spread Spectrum takes the low bit error probability than a DS Spread Spectrum system. Also, when the fading index m increases, the fading effect decrease, when the JSR(jamming to signal power ratio) increases ,the performance of a hybrid DS/SFH Spread Spectrum system improved than DS Spread Spectrum system. The result, we have been proved that performance of a hybrid DS/SFH Spread Spectrum was superior to DS Spend Spectrum system over Nakagami­m fading with tome jamming.

Noncoherent DPSK hybrid DS/SFH spread spectrum system over rayleigh fading channel in the presence of multiple tone jamming (다중 톤 방해신호가 존재하는 레일레이 페이딩 전송로에서 비동기 DPSK DS/SFH 복합 확산대역 시스템의 성능분석)

  • 박찬범;이재홍
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.1
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    • pp.9-15
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    • 1997
  • In this paper, the performance of a hybrid direct-sequence/slow-frequency-hoped (DS/SFH) spread-spectrum (SS) system with noncoherent DPSK modulation is considered. Th ebit error probability is derived ovef a rayleigh fading channel in the presence of multiple tone jamming. Numerical evaluations are presented for some combinations of system parameters. The performance of a hybrid DS/SFH SS system is shown to be inferior to that of a pure DS SS system at low jamming-to-signal power ratio (JSR). At high JSR, the performance of a pure DS SS system is shown to be the same as the worst case peformance of a hybrid DS/SFH SS system.

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Performance of a hybrid DS/SFH spread spectrum system over fading channel in the presence of multiple tone jamming (다중 톤방해신호가 존재하는 페이딩 전송로에서 DS/SFH 복합 확산대역시스템의 성능분석)

  • 박찬범;이재홍
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.11
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    • pp.10-18
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    • 1996
  • In this paper, performance of a hybrid direct-sequency/slow-frequency-hopped (DS/SFH) spread-spectrum (SS) system with coherent BPSK modulation is analyzed. The bit error probability is derived over a frequency=-selective rician fading channel in the presence of multiple tone jamming. The fading channel is modeled as the wide-sense stationary uncorrelated scattering (WSSUS) model. Numerical evaluations are presented for some combinations of system parameters. The performance of a hybrid DS/SFH SS system is shown to be inferior to that of a ure DS SS system at low jamming-to-signal power ratio (JSR). At high JSR, the performance of a pure DS SS system is shown to be the smae as the worst case performance of a hybrid DS/SFH SS system.

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Effects of Schisandra Fructus hexane fraction on high fat diet induced hyperlipidemic mice (오미자(五味子) 헥산 분획 추출물이 고지방 식이에 의한 고지혈증 생쥐의 지질대사 및 간 조직 유전자 발현에 미치는 영향)

  • Kim, Hyun-Young;Park, Sun-Mi;Kim, Young-Kyun
    • The Journal of the Society of Stroke on Korean Medicine
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    • v.15 no.1
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    • pp.13-28
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    • 2014
  • ■ Objectives The berries of Schisandra chinensis (Schisandra Fructus) are given the name Omiza in Koreane(五味子), and have been used asremedies for many ailments: to resist infections, increase skin health, and combat insomnia, coughing, and thirst. This study was designed to investigate the effects of Schisandra Fructus hexane fraction (SFH) on serum lipid levels in Hyperlipidemic mice. ■ Methods In this experiment, effects on total cholesterol, HDL-cholesterol, triglyceride, AST, ALT, fasting blood glucose in serum were measured. And in addition, histopathological and gene expression changes in liver tissue was also observed. ■ Results SFH did not affects weight gain, serum AST and ALT in hyperlipidemic mice. Oral administration of SFH lowered levels of total cholesterol and triglyceride, which were elevated by induction of hyperlipidemia. Finally, administration of SFH lowered fasting blood glucose significantly. And SFH also ameliorates anti-oxidative stress systems in internal organs which play key role in disease prevention. ■ Conclusion Results in our study suggest that SFH can prevent obese through regulation of dyslipidemia and hyperglycaemia.

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Performance of a Hybrid DS/SFH Spread Spectrum System over Nakagami Fading Channel in the Presence of Multiple Tone Jamming (다중 톤 방해신호가 존재하는 나카가미 페이딩 전송로에서 DS/SFH 복합 확산대역 시스템의 성능분석)

  • Byun, Woo-Sub;Sung, Koeng-Mo
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.36S no.8
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    • pp.8-16
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    • 1999
  • In this paper, the performance of a hybrid DS/SFH-SS(direct-sequence/slow-frequency-hopped spread-spectrum) system with coherent BPSK modulation over Nakagami fading channel in the presence of multiple tone jamming is analyzed. Because the Nakagami m-distribution can describe not only Rayleigh fading but also more general fluctuations involving a specular component by adjusting the value of the fading index m. It is known that for m=1 corresponds to Rayleigh fading, for $1/2{\le}m{\le}1$ corresponds to the worst case fading condition, for m>1 corresponds to Rician fading, and for $m{\to}{\infty}$ corresponds to the nonfading condition. The bit error probability is derived over Nakagami model and numerical evaluations are presented for some combinations of system parameters. The results show that as m increases, the bit error probability is better. Also, at a low JSR(jamming-to-signal power ratio), a pure DS-SS system can achieve lower bit error probability than a hybrid DS/SFH-SS system. But at a high JSR, a hybrid DS/SFH-SS system is shown to be superior to a pure DS-SS system. Therefore, it is demonstrated that without increasing the total system bandwidth, the performance of a hybrid DS/SFH-SS is superior to that of a pure DS-SS system in the presence of multiple tone jamming.

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Analysis of BER in Slow Frequency-Hopping System with False Alarm and Miss in Side Information (Side Information에 오경보와 미탐지가 존재할 띠 저속 주파수 도약 시스템의 BER분석)

  • 한상진;김용철;강경원;윤희철
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.11B
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    • pp.1556-1564
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    • 2001
  • Reed-Solomon code, block interleaving and SI (side information) are frequently used in SFH (slow frequency hopping) system. Erasing those symbols in the hit frequency slot greatly increases the error connection capacity. Packet error rate has been the major performance measure for SFH system. The analysis of BER has been limited to the case of perfect Sl, in which neither miss nor false alarm exists. BER with imperfect Sl has been obtained only by Monte Carlo simulation. In this paper, we present a unified solution to estimate BER with imperfect Sl. It is shown that previous formulae for packet error rate or BER with perfect Sl are special cases in the proposed solution. The computed BER with false alarm and miss of frequency hit is verified by comparing with the simulation result.

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Effects of Multione Interference on the Spectrum-Overlapped DS/SFH-SSMA System (스펙트럼 겹침이 있는 DS/SFH-SSMA 시스템의 다중톤 영향 분석)

  • Park, Jeong-Min;Ryu, Ho-Jin;Kim, Kie-Keun;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.3
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    • pp.446-450
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    • 2001
  • Performance of spectrum-overlapped BPSK DS/SFH-SSMA communication system is considered in MAI and MTI channel. SSMA system is studied that the frequency spectrums of DS spread signals are overlapped. The increase of overlapping makes ACI and processing gain larger simultaneously. Therefore, BER performance can be optimized by controlling the amount of overlapping. BER equation are derived far the overlapping BPSK DS/SFH-SSMA communication system in multitone interference channel. From the numerical analyses and the simulation results, it can be concluded that the BER performance is considerably improved in optimized overlapping system.

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