DocumentCode :
2773452
Title :
Effects of Side Information on Complexity Reduction in Superimposed Pilot Channel Estimation in OFDM Systems
Author :
Haghighi, Sahar Javaher ; Primak, Serguei ; Wang, Xianbin
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of Western Ontario, London, ON, Canada
fYear :
2010
fDate :
16-19 May 2010
Firstpage :
1
Lastpage :
5
Abstract :
A novel, reduced complexity iterative channel estimation algorithm for OFDM systems using superimposed pilots is proposed. It utilizes past channel estimations of double correlated channel as a side information to reduce number of iterations. Since pilots are available at all positions of the time-frequency OFDM grid in superimposed technique, the performance of the channel estimation does not degrade because of the variations of the fast fading channel between two pilots. On the other hand since no subcarrier is reserved for channel estimation purpose, superimposed pilot technique leads to improved spectral efficiency comparing to in-band OFDM pilots. However interference from data carrying signals made channel estimation more complex. In this paper, Least Square (LS) channel estimation followed by two dimensional Wiener filter for reducing OFDM symbol interference is done iteratively to achieve the Minimum Mean Square Error (MMSE). Small variations of the channel over each OFDM symbol duration are neglected due to a high data rate, but the values between different OFDM symbols are assumed correlated. The channel is modeled as a double selective, i.e. both frequency selectivity channel and Doppler shift are taken into consideration. Past channel estimates are used as side information for the present channel estimation to improve the forthcoming channel estimation at the first iteration and reduce the total number of iterations required.
Keywords :
Doppler shift; OFDM modulation; Wiener filters; channel estimation; fading channels; intersymbol interference; iterative methods; mean square error methods; spectral analysis; 2D Wiener filter; Doppler shift; MMSE; OFDM symbol interference; OFDM systems; complexity iterative channel estimation algorithm; complexity reduction; double correlated channel; fading channel; frequency selectivity channel; in-band OFDM pilots; least square channel estimation; minimum mean square error; signal interference; spectral efficiency; superimposed pilot channel estimation; superimposed technique; time-frequency OFDM grid; Channel estimation; Degradation; Fading; Interference; Iterative algorithms; Least squares approximation; Mean square error methods; OFDM; Time frequency analysis; Wiener filter;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Vehicular Technology Conference (VTC 2010-Spring), 2010 IEEE 71st
Conference_Location :
Taipei
ISSN :
1550-2252
Print_ISBN :
978-1-4244-2518-1
Electronic_ISBN :
1550-2252
Type :
conf
DOI :
10.1109/VETECS.2010.5493962
Filename :
5493962
Link To Document :
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