A Channel Estimation Method for a Highly Mobile OFDM Wireless Access System

Ryuhei FUNADA  Hiroshi HARADA  Yukiyoshi KAMIO  Shoji SHINODA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E88-B   No.1   pp.282-291
Publication Date: 2005/01/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.1.282
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
Keyword: 
OFDM,  channel estimation,  time-varying fading,  IEEE 802.11a,  

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Summary: 
Pilot-symbol-aided (PSA) channel estimation for OFDM wireless access systems enables the periodic estimation of channel frequency response by generating reference data from the received OFDM signals. The accuracy of this channel estimation can be improved through the average over a certain time period in each subcarrier-channel. However, the accuracy of the channel estimates by the average degrades as the Doppler shift is large due to a decrease in the average section size according to the Doppler shift for the tracking of the time-varying channel. This paper proposes a novel PSA channel estimation method to mitigate the influence of the noises and interferences. This method detects the channel estimates affected by the noises and interferences, and then removes them before the arithmetic or harmonic averaging to avoid propagating the influence of the noises and interferences. This paper also evaluated the proposed channel estimation method by clipping log-likelihood ratio (LLR) data to inspect the influence of the channel estimation on the LLR calculation by computer simulation.