Skip to main content


A Frame Synchronization and Frequency Offset Estimation Algorithm for OFDM System and its Analysis

Article metrics

  • 1065 Accesses

  • 13 Citations


Orthogonal frequency division multiplexing (OFDM) is a parallel transmission scheme for transmitting data at very high rates over time dispersive radio channels. In an OFDM system, frame synchronization and frequency offset estimation are extremely important for maintaining orthogonality among the subcarriers. In this paper, for a preamble having two identical halves in time, a timing metric is proposed for OFDM frame synchronization. The timing metric is analyzed and its mean values at the preamble boundary and in its neighborhood are evaluated, for AWGN and for frequency selective channels with specified mean power profile of the channel taps, and the variance expression is derived for AWGN case. Since the derivation of the variance expression for frequency selective channel case is tedious, we used simulations to estimate the same. Based on the theoretical value of the mean and estimate of the variance, we suggest a threshold for detection of the preamble boundary and evaluating the probability of false and correct detections. We also suggest a method for a threshold selection and the preamble boundary detection in practical applications. A simple and computationally efficient method for estimating fractional and integer frequency offset, using the same preamble, is also described. Simulations are used to corroborate the results of the analysis. The proposed method of frame synchronization and frequency offset estimation is applied to the downlink synchronization in OFDM mode of wireless metropolitan area network (WMAN) standard IEEE 802.16-2004, and its performance is studied through simulations.



  1. 1.

    Part 16: Air Interface for Fixed Broadband Wireless Access Systems IEEE Std. 802.16, 2004

  2. 2.

    Speth M, Fechtel SA, Fock G, Meyr H: Optimum receiver design for wireless broadband systems using OFDM—part 1. IEEE Transactions on Communications 1999,47(11):1668-1677. 10.1109/26.803501

  3. 3.

    Moose P: A technique for orthogonal frequency division multiplexing frequency offset correction. IEEE Transactions on Communications 1994, 42: 2908-2914. 10.1109/26.328961

  4. 4.

    Minn H, Bhargava V, Letaief K: A robust timing and frequency synchronization for OFDM systems. IEEE Transactions on Wireless Communications 2003, 2: 822-839.

  5. 5.

    Schmidl T, Cox D: Robust frequency and timing synchronization for OFDM. IEEE Transactions on Communications 1997, 45: 1613-1621. 10.1109/26.650240

  6. 6.

    Keller T, Hanzo L: Orthogonal frequency division multiplex synchronization techniques for wireless local area networks. Proceedings of 7th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC '96), October 1996, Taipei, Taiwan 963-967.

  7. 7.

    Keller T, Piazzo L, Mandarini P, Hanzo L: Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels. IEEE Journal on Selected Areas in Communications 2001,19(6):999-1008. 10.1109/49.926356

  8. 8.

    Haiyun T, Lau K, Brodersen R: Synchronization schemes for packet OFDM system. Proceedings of IEEE International Conference on Communications (ICC '03), May 2003, Anchorage, Alaska, USA 5: 3346-3350.

  9. 9.

    Zhang JL, Wang MZ, Zhu WL: A novel OFDM frame synchronization scheme. Proceedings of IEEE International Conference on Communications, Circuits and Systems and West Sino Expositions, July 2002, New York, NY, USA 1: 119-123.

  10. 10.

    van de Beek J-J, Sandell M, Börjesson PO: ML estimation of timing and frequency offset in multicarrier systems. In Tech. Rep. TULEA 1996:09. Lulea University of Technology, Division of Signal Processing, Lulea, Sweden; April 1996.

  11. 11.

    van de Beek J-J, Sandell M, Isaksson M, Börjesson PO: Low-complex frame synchronization in OFDM systems. Proceedings of IEEE International Conference on Universal Personal Communication (ICUPC '95), November 1995, Tokyo, Japan 982-986.

  12. 12.

    Muller-Weinfurtner SH: On the optimality of metrics for coarse frame synchronization. Proceedings of 9th IEEE International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC '98), September 1998, Boston, Mass, USA 533-537.

  13. 13.

    Wu M, Zhu W-P: A preamble aided symbol and frequency synchronization scheme for OFDM systems. Proceedings of IEEE International Symposium on Circuits and Systems (ISCAS '05), May 2005, Kobe, Japan 2627-2630.

  14. 14.

    Weinstein SB, Ebert PM: Data transmission by frequency division multiplexing using the discrete Fourier transform. IEEE Transactions on Communication Technology 1971,19(5):628-634. 10.1109/TCOM.1971.1090705

  15. 15.

    van Kempen G, van Vliet L: Mean and variance of ratio estimators used in fluorescence ratio imaging. Cytometry 2000,39(4):300-305. 10.1002/(SICI)1097-0320(20000401)39:4<300::AID-CYTO8>3.0.CO;2-O

  16. 16.

    Erceg V, Hari KVS, Smith MS, et al.: Channel models for fixed wireless applications. Tech. Rep. IEEE 802.16a-03/01 July 2003.

Download references

Author information

Correspondence to Ch Nanda Kishore.

Rights and permissions

Reprints and Permissions

About this article


  • Orthogonal Frequency Division Multiplex
  • Variance Expression
  • Orthogonal Frequency Division Multiplex System
  • Boundary Detection
  • Frequency Offset