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

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

Joint Symbol Detection and Channel Estimation Methods for an OFDM System in Fading Channels

페이딩 채널환경에서 OFDM 시스템에 대한 심볼 검출 및 채널 추정 기법

  • Published : 2001.03.25
Download PDF
⟨ Previous Next ⟩

Abstract

In this paper, we present the joint symbol detection and channel estimation for an orthogonal frequency division multiplexing (OFDM) system in fading channels. The proposed methods are based on decision-directed channel estimation (DDCE) method and their symbol detection is achieved by using Viterbi algorithm. This Viterbi decision-directed channel estimation (VDDCE) method tracks time-varying channels and detects a maximum likelihood symbol sequence. Recursive Viterbi decision-directed channel estimation (RVDDCE) method based on VDDCE method is proposed to shorten the detecting depth. In this method, channel estimate and Viterbi processing are recursively performed every interval of training symbol. Also, average chann'el estimation (ACE) technique to reduce the effect of additive white Gaussian noise (AWGN) is applied VDDCE method and RVDDCE method. These proposed methods arc demonstrated by computer simulation.

본 논문에서는 페이딩 채널 환경에서 OFDM 시스템의 채널추정과 심볼 검출이 결합된 방식들을 제안하였다. 제안된 방식들은 결정지향 채널 추정(DDCE) 방식에 근거하여 채널을 추정하며 비터비 알고리즘을 이용한 심볼 검출을 수행한다. 제안된 비터비 결정지향 추정 (VDDCE)방식은 시간상 변화하는 채널을 추척하고 ML 심볼 열을 검출 한다. VDDCE방식에 근거한 순환적 비터비 결정지향(RVDDCE) 방식에서는 복잡도를 줄이기 위해 검출될 심볼 열의 길이를 줄인다. 즉, 훈련 심볼의 간격동안에 채널 추정과 비터비 알고리즘이 일정 간격으로 반복적으로 수행되도록 한다. 또한，AWGN의 효과를 줄이기 위해 평균화 채널 추정(ACE) 방식을 VDDCE와 RVDDCE 방식에 적용하였다. 제안된 방식들은 컴퓨터 시뮬레이션으로 검증하였다.

Keywords

References

  1. D. Nielson, 'Microwave propagation measure-ments for mobile digital radio application,' in Proc. EASCON 77 Conf., pp. 14 -2A-14-2L, Sept. 1997
  2. Hikmet Sari, Georges Karam, and Isabelle Jeanclaudc, 'Transmission Methods for Digital Terrestrial TV Broadcasting,' IEEE Com-munications Magazine, pp. 100-109, Feb. 1995 https://doi.org/10.1109/35.350382
  3. J. S. Chow, J.-C. Tu, and J. M. Cioffi, 'A discrete multitone tranceiver systems for HDSL applications,' IEEE JSAC, vol 9, pp.5-14, Aug. 1991 https://doi.org/10.1109/49.93100
  4. Radio Equipment and Systems (RES); High Performance Radio Local Area Network (HIPERLAN TYPE 1); Functional specification, ETS 300 652, May 1997
  5. M. Alard, R. Lassalle, 'Principles of modulation and channel coding for digital broadcasting for mobile receivers', EBU Review-Technical, No. 224, Aug. 1987, pp168-109
  6. H. K. Lau and S. W. Cheng, 'A pilot symbol-added method used for digital signals in multipath environments,' in Proc. IEEE ICC'94, New Orleans, LA, May 1994, pp. 1126-1130
  7. F. Tufvesson and T. Maseng, 'Pilot assisted channel estimation for OFDM on mobile cellular system,' in Proc. VTC'97, May 1997, pp, 1639-1643 https://doi.org/10.1109/VETEC.1997.605836
  8. M. Sandell, O. Edfors, 'A Comparative Study of Pilot-based Channel Estimators for Wireless OFDM,' Research Report TULEA 1996:19, Division of Signal Processing, Lulea University of Technology
  9. S. K. Wilson, R. E. Khayata, and J. M. Cioffi, '16 QAM modulation with orthogonal division frequency multiplexing in a Rayleigh-fading environment, in Proc. VTC'94, Jun. 1994, pp. 1660-1664 https://doi.org/10.1109/VETEC.1994.345378
  10. H. K. SONG, J. H. PAIK, J. W. CHO, Y. B. DHONG, and Y. S. CHO, 'Frequency Synchronization and Channel Estimation for Wireless ATM,' IEICE Trans. Commun., vol. E82-B, no. 2., pp. 464-466, Feb. 1999
  11. Riccardo Raheli, Andrean Polydoros, and Ching-Kae Tzou, 'Per-Survivor Processing: A General Approach to MLSE in Uncertain Environments,' IEEE Trans. Commun., vol. 43, no. 2/3/4, pp. 354-364, Feb./Mar./Apr. 1995 https://doi.org/10.1109/26.380054
  12. N. Seshadri, 'Joint Data and Channel Estimation Using Blind Trellis Search Methods,' IEEE Trans. Commun., vol. 42, no. 2/3/4, pp. 1000-1011, Mar./ Apr./May 1994 https://doi.org/10.1109/TCOMM.1994.580208
  13. H. Meyr, M. Moeneclacy, S. A. Fechtcl, Digital Communication Receivers, A WileyInterscience Publication, JOlIN WILEY & SONS, INC., pp, 731-738, 1998