Space-time channel estimation and soft detection in time-varying multiaccess channels

  • Authors:

  • Joaquín Míguez;Luis Castedo

  • Affiliations:

  • Dept. Electrónica e Sistemas, Facultade de Informática, Universidade da Coruña, Campus de Elviña s/n, A Coruña 15071, Spain;Dept. Electrónica e Sistemas, Facultade de Informática, Universidade da Coruña, Campus de Elviña s/n, A Coruña 15071, Spain

  • Venue:
  • Signal Processing
  • Year:
  • 2003

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Abstract

This paper introduces an iterative space-time soft estimator (ISSE) that performs joint channel estimation and soft data detection in time-varying multiple-input multiple-output channels. The ISSE alternates channel estimation, taking explicitly into account the channel variability, and soft data detection. We suggest to implement the latter stage as a decision feedback (DF) structure consisting of two linear minimum mean square error (MMSE) matrix filters with an intercalated threshold detector. DF schemes are known to provide an appealing trade-off between performance and computational complexity. The main contribution of the paper is the channel estimation scheme. We derive a time-varying sequence of linear filters for channel estimation according to the MMSE principle. These filters depend both on the data and the second order statistics of the channel. Hence, we introduce a scalar approximation of the channel autocovariance function that relies on the statistical homogeneity of the multipath scattering. Under this assumption, we also design a globally convergent block-adaptive algorithm to estimate and track the second order statistics of a stationary channel. The robustness of the proposed approach when either the homogeneity or the stationarity hypotheses do not hold is shown through computer simulations.