Iterative maximum-likelihood sequence estimation for space-time coded systems

Yingxue Li, Costas N. Georghiades, Garng Huang

Research output: Contribution to journalArticle

73 Citations (Scopus)


In recent work on decoding space-time codes, it is either assumed that perfect channel state information (CSI) is present, or a channel estimate is obtained using pilot symbols and then used as if it were perfect to extract symbol estimates. In the latter case, a loss in performance is incurred, since the resulting overall receiver is not optimal. In this letter, we look at maximum-likelihood (ML) sequence estimation for space-time coded systems without assuming CSI. The log-likelihood function is presented for both quasi-static and nonstatic fading channels, and an expectation-maximization (EM)-based algorithm is introduced for producing ML data estimates, whose complexity is much smaller than a direct evaluation of the log-likelihood function. Simulation results indicate the EM-based algorithm achieves a performance close to that of a receiver which knows the channel perfectly.

Original languageEnglish
Pages (from-to)948-951
Number of pages4
JournalIEEE Transactions on Communications
Issue number6
Publication statusPublished - 1 Jun 2001



  • Complexity
  • EM algorithm
  • Performance
  • Sequence estimation
  • Space-time coding

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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