An EM based frequency domain channel estimation algorithm for multi-access OFDM systems

M. S. Sohail, T. Y. Al-Naffouri*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Channel estimation is an important prerequisite for receiver design. In this paper we present a semi-blind low complexity frequency domain based channel estimation algorithm for multi-access Orthogonal Frequency Division Multiplexing (OFDM) systems. Our algorithm is based on eigenvalues interpolation and makes a collective use of data and channel constraints. We exploit these constraints to derive a frequency domain maximum a posteriori (MAP) channel estimator. Furthermore, we develop a data aided (expectation maximization based) estimator incorporating frequency correlation information. The estimator is further enhanced by utilizing the time correlation information through a forward backward (FB) Kalman filter. We also explore various implementation for the FB Kalman filter. The simulation results are provided validating the applicability of the proposed algorithm.

Original languageEnglish (US)
Pages (from-to)1562-1572
Number of pages11
JournalSignal Processing
Issue number5
StatePublished - May 2010


  • Channel estimation
  • Kalman filtering
  • Model reduction
  • Multi-access systems
  • OFDM

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Software
  • Signal Processing
  • Computer Vision and Pattern Recognition
  • Electrical and Electronic Engineering


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