EURASIP Journal on Applied Signal Processing 
Volume 2002 (2002), Issue 5, Pages 507-516
doi:10.1155/S111086570200080X

Pilot-Symbol-Assisted Channel Estimation for Space-Time Coded OFDM Systems

King F. Lee1 and Douglas B. Williams2

 1Multimedia Architecture Lab, Motorola Labs, Schaumburg, 60196, IL, USA
2School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA
Received 31 May 2001; Revised 5 March 2002

Abstract

Space-time coded orthogonal frequency division multiplexing (OFDM) transmitter diversity techniques have been shown to provide an efficient means of achieving near optimal diversity gain in frequency-selective fading channels. For these systems, knowledge of the channel parameters is required at the receivers for diversity combining and decoding. In this paper, we propose a low complexity, bandwidth efficient, pilot-symbol-assisted (PSA) channel estimator for multiple transmitter OFDM systems. The pilot symbols are constructed to be nonoverlapping in frequency to allow simultaneous sounding of the multiple channels. The time-varying channel responses are tracked by interpolating a set of estimates obtained through periodically transmitted pilot symbols. Simulations are used to verify the effectiveness of the proposed estimator and to examine its limitations. It is also shown that the PSA channel estimator has a lower computational complexity and better performance than a previously proposed decision-directed minimum mean square error MMSE channel estimator for OFDM transmitter diversity systems.