A regional multimodulus algorithm for blind equalization of QAM signals: Introduction and steady-state analysis

  • Authors:
  • JoãO Mendes Filho;Maria D. Miranda;Magno T. M. Silva

  • Affiliations:
  • Escola Politécnica, University of São Paulo, SP, Brazil;Escola Politécnica, University of São Paulo, SP, Brazil;Escola Politécnica, University of São Paulo, SP, Brazil

  • Venue:
  • Signal Processing
  • Year:
  • 2012

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Abstract

It is well known that constant-modulus-based algorithms present a large mean-square error for high-order quadrature amplitude modulation (QAM) signals, which may damage the switching to decision-directed-based algorithms. In this paper, we introduce a regional multimodulus algorithm for blind equalization of QAM signals that performs similar to the supervised normalized least-mean-squares (NLMS) algorithm, independently of the QAM order. We find a theoretical relation between the coefficient vector of the proposed algorithm and the Wiener solution and also provide theoretical models for the steady-state excess mean-square error in a nonstationary environment. The proposed algorithm in conjunction with strategies to speed up its convergence and to avoid divergence can bypass the switching mechanism between the blind mode and the decision-directed mode.