Channel Compensation of Variable Symbol Timing Offset in Non-synchronized OFDM System

  • Jae-Ho Lee
  • Dong-Joon Choi
  • Nam-Ho Hur
  • Whan-Woo Kim
Part of the Lecture Notes in Electrical Engineering book series (LNEE, volume 235)


In this paper, we propose the method of channel compensation with phase rotator (PR) when there is variable symbol timing offset (STO) in non-synchronized orthogonal frequency division multiplexing (OFDM) system. Because the symbol timing of OFDM symbols is estimated within cyclic prefix (CP) interval, a STO occurs and makes the received quadrature amplitude modulation (QAM) symbols rotated. These rotated QAM symbols can be compensated with frequency domain equalizer (FEQ). However, because the drift of symbol timing occurs in non-synchronized OFDM system, symbol timing should be estimated every OFDM symbols. Thus, the STO of the first OFDM symbol can be different from it of other OFDM symbols. PR compensates the phase difference caused by STO differences of OFDM symbols before FEQ. We show that the uncoded-bit error rate (BER) between the synchronized OFDM system and the proposed non-synchronized OFDM system is the same under additive white Gaussian noise (AWGN) and multipath channel.


Cyclic prefix Symbol timing offset Phase rotator Frequency domain equalizer 



This work was supported by the IT R&D program of KCC. [10035709, Development of Next Generation Digital Cable Transmission Technology].


  1. 1.
    Barry JR, Lee EA, Messerschmitt DG (2003) Digital communication, 3rd edn. Springer, New York Google Scholar
  2. 2.
    Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2) (2009) DVB Document A138Google Scholar
  3. 3.
    Implementation Guidelines for a second generation digital cable transmission system (DVB-C2) (2010) DVB Document A147Google Scholar
  4. 4.
    Cho SI, Kang KM (2010) A low-complexity 128-point mixed-radix FFT processor for MB-OFDM UWB systems. ETRI J 32(1):1–10CrossRefGoogle Scholar
  5. 5.
    Jung SY, Kim SH (2010) Channel estimation and LDPC code puncturing schemes based on incremental pilots for OFDM. ETRI J 32(4):603–606MathSciNetCrossRefGoogle Scholar
  6. 6.
    Van de Beek JJ, Sandell M, Isaksson M, Börjesson PO (1995) Low complex frame synchronization in OFDM systems. In: Proceedings of IEEE international conference on universal personal communications, pp 982–986Google Scholar
  7. 7.
    Van de Beek JJ, Sandell M, Börjesson PO (1997) ML estimation of time and frequency offset in OFDM systems. IEEE Trans Signal Process 45(7):1800–1805MATHCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Jae-Ho Lee
    • 1
  • Dong-Joon Choi
    • 1
  • Nam-Ho Hur
    • 1
  • Whan-Woo Kim
    • 2
  1. 1.Digital Broadcasting Research DivisionETRIYuseong-gu, DaejeonSouth Korea
  2. 2.Electrical and Computer EngineeringChungnam National UniversityYuseong-gu, DaejeonSouth Korea

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