Maximum likelihood blind channel estimation in the presence of Doppler shifts


Cirpan H. A. , TSATSANIS M.

IEEE TRANSACTIONS ON SIGNAL PROCESSING, vol.47, no.6, pp.1559-1569, 1999 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 47 Issue: 6
  • Publication Date: 1999
  • Doi Number: 10.1109/78.765125
  • Title of Journal : IEEE TRANSACTIONS ON SIGNAL PROCESSING
  • Page Numbers: pp.1559-1569

Abstract

Transmitter/receiver motion in mobile radio channels may cause frequency shifts in each received path due to Doppler effects. Most blind equalization methods, however, assume time-invariant channels and may not be applicable to fading channels with severe Doppler spread. In this paper, we address the problem of simultaneously estimating the Doppler shift and channel parameters in a blind setup. Both deterministic and stochastic maximum likelihood methods are developed and iterative solutions proposed. The stochastic maximum likelihood solution is based on the modified version of the Baum-Welch algorithm, which originated in the study of hidden Markov models. The proposed methods are well suited for short data records appearing in TDMA systems. Identifiability and performance analysis issues are discussed, and Cramer-Rao bounds are derived. In addition, some illustrative simulations are presented.