대한전자공학회논문지SD (Journal of the Institute of Electronics Engineers of Korea SD)

대한전자공학회 (The Institute of Electronics and Information Engineers)
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SCAE와 SCAD를 이용한 광 CDMA시스템에서 간섭패턴 분석

Interference Pattern Analysis in the Optical CDMA system using the SCAE and SCAD

  • Kang, Tae-Gu (Department of Electronic Engineering, Chung-Ang University) ;
  • Choi, Jae-Kyong (Department of Electronic Engineering, Chung-Ang University) ;
  • Park, Chan-Young (Department of Electronic Engineering, Chung-Ang University) ;
  • Choi, Young-Wan (Department of Electronic Engineering, Chung-Ang University)
  • 발행 : 2000.01.01
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초록

Series Coupler Access Encodler(SCAE)와 Series Coupler Access Decoder(SCAD)를 이용한 광CDMA(Code Division Multiple Access)시스템에서 광정합필터 특성을 삼차신호까지 고려하여 분석하였다. 기존의 연구에서는 SCAE 및 ACAD를 평가할 때, 일차신호만을 고려하여 시스템의 성능을 분석하여 성능평가가 정확하지가 않았다. SCAE 및 SCAD는 커플러 수를 증가함에 따라 여러 형태의 간섭신호들을 가지므로, 이러한 신호들이 자기상관과 상호상관 세기를 변화시킨다. 그러므로 좀 더 정확한 시스템 성능을 분석하기 위해서는 간섭신호들의 특성을 연구할 필요성이 있다. 본 논문에서는 복호화 되는 광신호를 삼차신호까지 수학적으로 해석하였고, 시스템의 자기상관과 상호상관에 미치는 영향을 모의실험을 통해 분석하였다. 커플러 수 증가에 따라 나타나는 삼차신호들이 간섭신호 형태가 되어 peak to side-lobe ratio를 감소키기는 요인으로 작용됨을 정량적으로 확인하였다. 간섭신호들의 크기는 ${\alpha}$(coupling coefficient)값이 커질수록 증가하였으며, 커플러 개수(N)=5, ${\alpha}$=0.5인 조건에서 삼차신호까지 고려한 peak to side-lobe ratio는 3.75 dB까지 열화됨을 밝혔다. 또한, 일차신호의 main-lobe세기에 의해 수신기의 임계레벨을 결정한다면, 삼차신호에 의해 증가된 side-lobes세기 때문에 SCAE와 SCAD를 이용한 광 CDMA system에 다중 접속할 수 있는 사용자 수가 제한됨을 알 수 있었다.

We have analyzed optical matched filters considering the third order signals in the optical code division multiple access (CDMA) system based on optical series coupler access encoder (SCAE) and series coupler access decoder (SCAD). In previous studies, the performance evaluation of the optical CDMA system using SCAE and SCAD was not sufficiently accurate because they analyzed system performance only considering the first order signals. Since optical SCAE and SCAD intrinsically have high order signals of various patterns as the number of coupler increases, they change auto- and cross-correlation intensities. Thus, it is necessary to investigate properties of the third order signals so that we may analyze the exact performance of system. In this paper, we mathematically interpret the optical signals up to the third order, and analyzed the effects of th third order signals on auto- and cross-correlation intensities. In result, as ${\alpha}$(coupling coefficient) value increases, the intensity of the third order signals increases. It is found that the peak to side-lobe ratio considering the third order signals is degraded by 3.75 dB at N(coupler number)=5 and ${\alpha}$=0.5. Also if threshold value in receiver is set by main-lobe peak of the first order signals, it is found that the number of users in an optical CDMA system is limited because the intensity peak of side-lobes is raised by the third order signals.

키워드

참고문헌

  1. J. A. Salehi, 'Emerging Optical Code Division Multiple Access Communication System', IEEE Network, pp.31-39, March 1989 https://doi.org/10.1109/65.21908
  2. F. R. K. Chung, J. A. Salehi, and V. K. Wei, 'Optical orthogonal codes: Design, analysis, and application', IEEE Trans. Inform. Theory, vol.37, May 1989 https://doi.org/10.1109/18.30982
  3. J. A. Salehi, 'Code division multiple-access techniques in optical fiber networks- Part I : Fundamental principles', IEEE Trans. Commun., vol.37, pp.824-833, Aug. 1989 https://doi.org/10.1109/26.31181
  4. H. M. Kwon, 'Optical Orthogonal Code Division Multiple Access System part II: Multibits/sequence Period OOCDMA', ICC.91, pp.618-621
  5. Alex W. Lam and Awais M. Hussain, 'Performance Analysis of Direct-detection Optical CDMA Communication System with Avalanche Photodiodes', IEEE Transactions on Communications, Vol.40, pp.810-819, April 1992 https://doi.org/10.1109/26.141436
  6. T. J. Healy, 'Coding and decoding for Code Division Multiple user communication system' IEEE Trans. Commun., vol. COM-33, pp.310-316, 1985
  7. Wing C. Kwong, Philippe A. Perrier and Paul H. Prucnal, 'Performance Comparison of Asynchronous and Synchronous Code-Division Multiple-Access Techniques for Fiber-Optic Local Area Networks', IEEE Transactions on Communications, Vol.39, pp.1625-1634, Nov. 1991 https://doi.org/10.1109/26.111444
  8. Jawad A. Salehi, 'Optical CDMA via Temporal Code', IEEE Trans. Commun., Vol.40, No.7, pp.1162-1170, July 1992 https://doi.org/10.1109/26.153360
  9. E. Marom, 'Optical delay line matched filters', IEEE Trans. Circuits Syst., vol. CAS-25, pp.360-364, June 1978 https://doi.org/10.1109/TCS.1978.1084485
  10. J. A. Salehi et al., 'Coherent Ultrashort Light Pulse Code-Division Multiple Access Communication System,' Journal of Lightwave Technology, Vol.8, pp.478-491, March 1990 https://doi.org/10.1109/50.50743
  11. D. Brady, and S. Verdu, 'A semiclassical analysis of Optical code division multiple access', IEEE Trans. Commun. vol.39 pp.85-93, Jan. 1991 https://doi.org/10.1109/26.68279
  12. J. A. Salehi and C. A. Brackett, 'Code division multiple-access techniques in optical fiber networks Part II:System Performance Analysis,' IEEE Trans. Commun., vol.37, pp.834-842, Aug. 1989 https://doi.org/10.1109/26.31182