Nonlinear blind equalization schemes using complex-valued multilayer feedforward neural networks

Cheolwoo You, Daesik Hong

Research output: Contribution to journalArticle

101 Citations (Scopus)


Among the useful blind equalization algorithms, stochastic-gradient iterative equalization schemes are based on minimizing a nonconvex and nonlinear cost function. However, as they use a linear FIR filter with a convex decision region, their residual estimation error is high. In this paper, four non-linear blind equalization schemes that employ a complex-valued multilayer perceptron instead of the linear filter are proposed and their learning algorithms are derived. After the important properties that a suitable complex-valued activation function must possess are discussed, a new complex-valued activation function is developed for the proposed schemes to deal with QAM signals of any constellation sizes. It has been further proven that by the nonlinear transformation of the proposed function, the correlation coefficient between the real and imaginary parts of input data decreases when they are jointly Gaussian random variables. Last, the effectiveness of the proposed schemes is verified in terms of initial convergence speed and MSE in the steady state. In particular, even without carrier phase tracking procedure, the proposed schemes correct an arbitrary phase rotation caused by channel distortion.

Original languageEnglish
Pages (from-to)1442-1455
Number of pages14
JournalIEEE Transactions on Neural Networks
Issue number6
Publication statusPublished - 1998 Dec 1

All Science Journal Classification (ASJC) codes

  • Software
  • Computer Science Applications
  • Computer Networks and Communications
  • Artificial Intelligence

Fingerprint Dive into the research topics of 'Nonlinear blind equalization schemes using complex-valued multilayer feedforward neural networks'. Together they form a unique fingerprint.

  • Cite this