• Title, Summary, Keyword: Chaos Map

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Chaos의 세계(II)

  • 서용권
    • Journal of the KSME
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    • v.31 no.1
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    • pp.68-79
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    • 1991
  • 이 글에서는 다음의 내용에 대하여 알아보았다. Duffing - holmes 방정식에서의 Chaos Logistic map에서의 Chaos 기타 시스템에서의 Chaos 1) Henon map 2) Bouncty bau map (standard map) 3) 진자에서의 Chaos 4) Taylor-Couette유동 5) Fluid drop Chaos 6) Surface wave Chaos Lyapunov 지수 (Exponent)

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New Chaos Map for BER Performance Improvement in Chaos Communication System Using CDSK (상관지연편이변조 방식의 혼돈(Chaos) 통신 방식에서 비트오류율 성능 향상을 위한 새로운 혼돈 지도)

  • Lee, Jun-Hyun;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.8
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    • pp.629-637
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    • 2013
  • Chaos communication systems have the characteristics such as non-periodic, wide-band, non-predictability of signals and easy implementation. There have been many studies about chaos communication systems because of these advantages. But, chaos communication systems have low BER(Bit Error Rate) compare to general digital communication system. Existing researches on chaos communication systems only analyze BER performance according to various chaos maps. There are no studies on analysis of BER performance according to PDF(Probability Density Function) of chaos maps. In this paper, we analyze the BER performance according to changing parameter, equation, and initial values of chaos map's PDF. In addition, we propose new chaos map to improve BER performance. Simulation results show that BER performance of CDSK(Correlation Delay Shift Keying) is changed when PDF of chaos map changed. And the proposed chaos map has a better BER performance compare to previous chaos maps such as Tent map, Logistic map, and Henon map.

Characteristic Analysis of Proposed Chaos Map in CDSK System (CDSK 변조 방식에서 제안한 카오스 맵의 특성 분석)

  • Lee, Jun-Hyun;Ryu, Heung-Gyoon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.5
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    • pp.44-50
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    • 2014
  • Chaos communication system is one of the security algorithms that is applied to improve the security. Chaos signal is non-linear, and it is generated randomly according to the initial conditions. Also, chaos communication system has characteristics such as non-periodic, wide-band, non-predictability of signals and easy implementation. So, security of chaos communication system is superior, and it has low interception probability and good anti-jamming characteristic. However, BER performance is worse than digital communication system, because it has many self interference signal in case of CDSK system. To improve these disadvantages, we analyze the PDF trend which can improve the BER performance in existing study, and we proposed a chaos map. And, proposed chaos map was defined as the 'Boss map'. Generally, BER performance is changed according to initial values, parameters and spreading factors. Therefore, in this paper, we will introduce PDF trends which can improve the BER performance, and will describe about Boss map. Also, characteristics of Boss map is analyzed by evaluating the BER performance of Boss map according to initial values, parameters and spreading factors. As a result, while maintaining the similar BER performance, initial value of Boss map can be selected from 0 to 1.2, and BER performance is best when parameter alpha is 2.5. Also, BER performance is best when spreading factor is 50.

BER Performance Evaluation of Boss Map According to Delay Time in CDSK Modulation Scheme and Chaos Transceiver (CDSK 변조 방식과 카오스 송수신기의 지연시간에 따른 Boss Map의 BER 성능 평가)

  • Lee, Jun-Hyun;Keum, Hong-Sik;Lee, Dong-Hyung;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.7
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    • pp.365-371
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    • 2014
  • Chaos communication system is possible to improve the system security by using chaos signal. Further, it is possible to reduce the possibility of eavesdropping, and have strong characteristics from interference signal and jamming signal. However, BER(Bit Error Rate) performance of chaos system is worse than digital communication system. By this reason, researches in order to improve the BER performance of chaos communication system are being actively studied. In previous studies, we proposed a novel chaos map for BER performance improvement, and called it 'Boss map'. Also, we proposed a novel chaos transceiver for BER performance improvement. However, BER performance is evaluated differently according to delay time in transceiver. Therefore, in order to use Boss map effectively, we should find the optimal delay time in proposed chaos transceiver. In this paper, when Boss map is used, we evaluate BER performance of CDSK(Correlation Delay Shift Keying) system and novel chaos transceiver according to delay time. After evaluation of BER performance according to delay time, we find a delay time that is possible to have best BER performance in CDSK system and novel chaos transceiver.

CHAOS AND LYAPUNOV EXPONENT

  • Yu, Se-Ra;Kim, Yon-Mi
    • The Pure and Applied Mathematics
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    • v.7 no.2
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    • pp.87-100
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    • 2000
  • In this paper, we try to approach chasos with numerical method. After investigating nonlinear dynamcis (chaos) theory, we introduce Lyapunov exponent as chaos\`s index. To look into the existence of chaos in 2-dimensional difference equation we computes Lypunov exponent and examine the various behaviors of solutions by difurcation map.

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Anti-Jamming Performance of Chaos Communications System Using DCSK and CDSK Modulation Method (DCSK와 CDSK 방식을 사용하는 카오스 통신 시스템의 항재밍 특성)

  • Lee, Jun-Hyun;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.4
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    • pp.417-425
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    • 2013
  • Digital communication technology have been focused on the higher data efficiency and the effective coding of information. Also, it is very important to improve security and minimize the interference of the external sources, Chaos communications system is studied to improve security and minimize the interference by effective encoding of information in the nonlinear systems such as DCSK(Differential Chaos Shift Keying) and CDSK(Correlation Delay Shift Keying). In this paper, we evaluate anti-jamming performance of chaos communications system using the DCSK and CDSK system. The simulation results show that the Gauss iterated map has better BER performance than the other maps(tent map, logistic map, Henon map). Also, DCSK and CDSK system can get the better anti-jamming performance by applying different chaotic maps.

Detecting Chaotic Motions of a Piecewise-Linear System in the Noisy Fields by Mean Poincare Maps (평균 포인케어맵을 이용한 Noisy Field에서의 chaos거동의 검출방법)

  • 마호성
    • Computational Structural Engineering
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    • v.10 no.4
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    • pp.239-249
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    • 1997
  • The method to distinguish chaotic attractors in the perturbed response behaviors of a piecewise-linear system under combined regular and external randomness is provided and examined. In the noisy fields such as the ocean environment, excitation forces induced by wind, waves and currents contain a finite degree of randomness. Under external random perturbations, the system responses are disturbed, and consequently chaotic signatures in the response attractors are not distinguishable, but rather look just random-like. Mean Poincare map can be utilized to identify such chaotic responses veiled due to the random noise by averaging the noise effect out of the perturbed responses. In this study, the procedure to create mean Poincare map combined with the direct numerical simulations is provided and examined. It is found that mean Poincare maps can successfully distinguish chaotic attractors under stochastic excitations, and also can give the information of limit value of noise intensity with which the chaos signature in system responses vanishes.

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Chaos on the Rocking Vibration of Rigid Block Under Two Dimensional Sinusodial Excitation (In the Case of No Sliding Occurrence) (2차원 정현파 가진을 받는 강체블록의 록킹진동에 있어서의 카오스 (미끄럼이 없는 경우에 대하여))

  • 정만용;김정호;김지훈;양광영;양인영
    • Journal of the Korean Society of Safety
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    • v.14 no.2
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    • pp.42-51
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    • 1999
  • This research deals with the non-linearities associated with impact and sliding for the rocking behavior of rigid block subjected to two dimensional excitation of horizontal and vertical direction. The non-linearities examined of impact between block and base: The transition of two governing rocking equations, the abrupt reduction in kinetic energy associated with impact. In this study, the rocking vibration system of two types are considered for several friction condition. One is the undamped rocking vibration system, disregarding energy dissipation at impact and the other is the damped rocking system, including energy dissipation at impact. The response analysis by non-dimensional rocking equation is carried out for the change of excitation amplitude. The chaos responses were discovered in the wide response region, particularly, in the case of high vertical excitation and their chaos characteristics are examined by Poincare map, power spectra and Lyapunov Exponent. The complex behavior of chaos response, in the phase space, were illustrated by Poincare map. Therefore, Poincare map will be a significant material in order to understand chaos of rocking system.

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Nonlinear Rocking Vibration Characteristics for Rigid Block Subjected to Horizontal Sinusoidal Excitation (수평방향의 정현파 가진을 받는 강체 블록의 비선형 록킹진동특성)

  • 정만용;김정호;김지훈;정낙규;양인영
    • Journal of the Korean Society of Safety
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    • v.14 no.4
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    • pp.3-12
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    • 1999
  • This research concentrates on the influence of non-linearities associated with impact for the nonlinear rocking behavior of rigid block subjected to one dimensional sinusoidal excitation of horizontal direction. The transition of two governing rocking equations, the abrupt reduction in the kinetic energy associated with impact, and sliding motion of block. In this study, two type of rocking vibration system are considered. One is the undamped rocking vibration system, disregarding energy dissipation at impact and the other is the damped rocking system, including energy dissipation and sliding motion. The response analysis using non-dimensional rocking equation is carried out for the change of excitation parameters and friction coefficient. The chaos responses were discovered in the wide response region, particularly, for the case of high excitation amplitude and their chaos characteristics were examined by the time history, Poincare map, power spectra and Lyapunov Exponent of rocking responses. The complex behavior of chaos response, in the phase space, were illustrated by Poincare map. The bifurcation diagram and Poincare map were shown to be effective in order to understand chaos of rocking system.

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Research on the Image Encryption Method using a Linear-structure Chaos System (선형구조 혼돈계를 이용한 이미지 암호와 방법 연구)

  • Cho, Chang Ho;Yim, Geo Su
    • Journal of the Korea Society of Digital Industry and Information Management
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    • v.7 no.4
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    • pp.75-79
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    • 2011
  • With the rapid growth of digital communication and the internet, the importance of conducting research on data encryption methods is increasing. Some of the pertinent researches that have been conducted so far introduced data encryption methods using chaos systems, and numerous researches are currently being conducted on such methods. The signals produced by the chaos systems are called "determined noise," and if this is applied to data encryption, very effective results can be obtained. Using the Henon map, the relationship between the non-linearity of the chaos system and the strength of encryption was analyzed, and a linear-structure chaos system that uses non-linearity as a variable for encryption strength was constructed. Using the constructed chaos system, an image was encrypted and decoded, and the correlation coefficient of the linear-structure chaos system's performance was calculated and then analyzed.