中文

Journal of Shanghai University（Natural Science Edition） ›› 2017, Vol. 23 ›› Issue (1): 138-146.doi: 10.3969/j.issn.1007-2861.2015.02.011

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Estimation algorithm of sampling clock frequency offset for OOFDM system based on training sequence

ZHANG Zhen, SONG Yingxiong, ZHANG Junjie, DUN Han, GUO Songlin, XUE Ziwei   

  1. Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072, China
  • Received:2015-04-22 Online:2017-02-28 Published:2017-02-28

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Abstract:

This paper studies sampling clock synchronization for optical orthogonal frequency division multiplex (OOFDM) systems, and proposes a simple sampling clock frequency offset (SCFO) estimation algorithm for hardware implementation based on crosscorrelation properties of the training sequence. The main idea is as follows. First, correlation between the received training sequence and the known training sequence is obtained, and then sampling clock frequency offset found with a few adders and one divider based on the property that an additional sampling point is introduced when the cross-correlation
value periodically changes a cycle. An optical OFDM system with intensity-modulation and direct-detection (IMDD-OFDM) is set up to show performance of the algorithm. Experimental and simulated results indicate that the algorithm has good accuracy and noise immunity.

Key words:  cross-correlation ,  sampling clock synchronization ,  training sequence, optical orthogonal frequency division multiplex (OOFDM)