Likelihood Ratio Test-Based Blind Carrier Frequency Offset Estimation for Coherent Optical OFDM Systems

Yangfan Xu, Xinwei Du, Changyuan Yu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)

Abstract

This letter proposes two carrier frequency offset (CFO) estimators by utilizing the likelihood ratio test (LRT) for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems. The zero-information in real and imaginary parts of the effective data subcarriers can be detected by LRT for flexible modulation formats. An LRT-based blind estimator (LRT-BE) algorithm is then proposed by using power fluctuations of the zero-information. An LRT-based simplified fine estimator (LRT-SFE) is subsequently developed to reduce complexity by approximating the cost function as a cosine function. The closed-form expression of CFO estimate is derived by using three arbitrary test values, which is computationally efficient. The blind zero-information detection procedure transfers the LRT-based methods to a sort of semi-blind estimator which improves the estimation accuracy, and the optimal threshold derived by LRT makes the proposed methods be robust to M -QAM modulations. Simulation results verify the accuracy, flexibility and efficiency of the proposed algorithms. At the MSE of 10-4, the SNR gain of LRT-SFE is upto 6.5 dB compared to other blind estimators.

Original languageEnglish
Pages (from-to)1589-1593
Number of pages5
JournalIEEE Communications Letters
Volume27
Issue number6
DOIs
Publication statusPublished - 1 Jun 2023

Keywords

  • blind
  • Carrier frequency offset
  • CO-OFDM
  • likelihood ratio test

ASJC Scopus subject areas

  • Modelling and Simulation
  • Computer Science Applications
  • Electrical and Electronic Engineering

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