Time dispersion and delay spread estimation for adaptive OFDM systems


Yücek T., ARSLAN H.

IEEE Transactions on Vehicular Technology, vol.57, no.3, pp.1715-1722, 2008 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 57 Issue: 3
  • Publication Date: 2008
  • Doi Number: 10.1109/tvt.2007.909247
  • Journal Name: IEEE Transactions on Vehicular Technology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1715-1722
  • Keywords: adaptation, delay spread estimation, frequency selectivity, orthogonal frequency division multiplexing (OFDM), time dispersion
  • Istanbul Medipol University Affiliated: Yes

Abstract

Time dispersion is one of the most important characteristics of the wireless channel. The knowledge about the time dispersion of a channel can be used to design better systems that can adapt themselves to the changing nature of the transmission medium. In this paper, algorithms to estimate the time dispersion (frequency selectivity) of the channel, which use the frequency-domain channel estimates or the frequency-domain-received signal, are proposed. The proposed algorithms estimate the power delay profile (PDP) from which the two important dispersion parameters, namely root-mean-squared (RMS) delay spread and maximum excess delay of the channel, are estimated. It is shown that synchronization errors bias the performance of the estimators based on the channel correlation, and this bias is removed by obtaining the PDP using the magnitude of the channel estimates. Moreover, the Cramér-Rao lower bound (CRLB) for the estimation of the RMS delay spread is derived, and the performances of the proposed algorithms are compared against this theoretical limit. © 2008 IEEE.