Journal of the Institute of Electronics Engineers of Korea TC (대한전자공학회논문지TC)

The Institute of Electronics and Information Engineers (대한전자공학회)
권호 표지

Analysis of Smart Antenna Performance Improving the Robustness of OFDM to Rayleigh Fading

레일리 페이딩 내구성을 개선시키는 OFDM 스마트안테나의 성능 분석

  • 홍영진 (동명대학교 전기공학과)
  • Received : 2011.01.07
  • Accepted : 2011.04.18
  • Published : 2011.04.25
Download PDF
⟨ Previous Next ⟩

Abstract

In order to augment the robustness of OFDM system to Rayleigh multipath fading, there exist two smart antenna algorithms, namely, Pre-FFT smart antenna and Post-FFT smart antenna. After the mathematical modeling of both smart antenna algorithms, computer simulations have been carried to compare and analyze the performance of generalized eigen problem based Pre-FFT algorithm and the performance of Wiener solution based Post-FFT algorithm. It has been shown that the Post-FFT smart antenna far outperforms the Pre-FFT smart antenna due to the computational complexities. Especially it is so when the multipath signal arrives at beyond the guard interval and a rich co-channel interferer is introduced. Performance of a subcarrier clustering method proposed to lessen the computing load has been compared to that of a typical Wiener solution based Post-FFT smart antenna. Performance comparison between MRC(Maximum Ratio Combining) diversity based Post-FFT algorithm and typical Post-FFT algorithm has also been carried.

OFDM(Orthogonal Frequency Division Multiplexing) 시스템의 Rayleigh fading 에 대한 내구성을 증대시키기 위하여 채용되는 2 종류의 스마트안테나 즉 귀납적인 고유공간법에 기반한 FFT(Fast Fourier Transform) 전단 스마트안테나와 Wiener 해법에 기반한 FFT 후단 스마트안테나의 가중치벡터 갱신의 수학적 모델을 정의한 후 컴퓨터 모의실험에 의거, 그 성능들을 비교 분석하였다. 장치의 복잡성의 대가로 FFT 후단 스마트안테나의 성능이 훨씬 우수함이 보여졌고 특히 다중경로의 시간지연이 OFDM 가드타임을 벗어날 경우와 강한 동일채널 간섭신호가 존재할 경우의 FFT 후단 스마트안테나 성능의 우월성이 입증되었다. FFT 후단 스마트안테나의 복잡성을 줄이기 위하여 제안된 부채널 군집형 가중치벡터 갱신 안테나와 부채널 전력 기반의 MRC(Maximum Ratio Combining) 다이버시티 안테나 기법의 성능이 전형적인 Wiener 해법에 기반한 FFT 후단 스마트안테나와 비교되었다.

Keywords

References

  1. B. le. Floch, M. Alard and C. Berrou, "Coded orthogonal frequency division multiplex," Proc. IEEE, vol. 83, no. 6, June 1995.
  2. J. Bingham, "Multicarrier modulation for data transmission: an idea whose time has come," IEEE Commun. Mag., vol. 28, pp. 5-14, May 1990. https://doi.org/10.1109/35.54342
  3. S. Hara, M. Mouri, M. Okada and N. Morinaga, "Transmission performance analysis of multi-carrier modulation in frequency selective fast Rayleigh fading channel," Wireless Pers. Commun. vol. 2, no. 4, pp.335-356, 1995/1996. https://doi.org/10.1007/BF01099340
  4. T. Ohgane, H. Sasaoka, N. Matsuzawa, K. Takeda, and T. Shimura, "A development of GMSK/TDMA system with CMA adaptive array for land mobile communications," Proc. of 1991 Conf. on Veh. Technol., pp.172 1991.
  5. A. F..Naguib and A. Paulraj, "Capacity improvement with base-station antenna arrays in cellular CDMA," IEEE Trans..Veh. Technol, vol. 43, pp. 691, Aug. 1994. https://doi.org/10.1109/25.312780
  6. 홍영진, "CDMA 상향채널용 CGM-LMS 접목 적응빔형성 알고리듬에 관한 연구," 한국통신학회논문지 vol. 32, no. 9, pp. 895-904, Sep. 2007.
  7. J. Winters, "Smart antennas for wireless systems," IEEE Personal Commun. Mag., pp. 23-27, Feb. 1998.
  8. A. P. Ansbro, S. L. Drakul, A. Fanigliulo and G. Fontana, "Performance analysis of an adaptive antenna array for GSM/UMTS," Proc. of 1998 Conf. on Veh. Technol., pp.1176, 1998.
  9. R. Alihemmati, E. Jedari, A. Enayati, A.Shishegar, M. Roozbahani, and G. Dadashzadeh, "Performance of the pre/post-FFT smart antenna methods for OFDM-based wireless LANs in an indoor channel with interference," Proc. of ICC2006 Conference, vol. 9, pp. 4291-4296, 2006.
  10. Y. Li and N. Sollenberger, "Adaptive antenna arrays for OFDM systems with cochannel interference," IEEE Trans. on commun., vol. 47, no. 2, pp. 217-229, Feb. 1999. https://doi.org/10.1109/26.752127
  11. M. Budsabathon, Y. Hara, and S. Hara, "Optimum beamforming for pre-FFT OFDM adaptive antenna array," IEEE Trans. on Vehicular Technology, vol. 53, no. 4, pp. 945-955, July 2004. https://doi.org/10.1109/TVT.2004.830939
  12. Y. Sun and H. Matsuoka, "A novel adaptive antenna architecture - subcarrier clustering for high-speed OFDM systems in presence of rich co-channel interference," IEEE VTC'2002, vol. 3, pp. 1564-1568, May 2002.