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A Time-Domain Joint Adaptive Channel Estimator and Equalizer for Multi-Carrier Systems in Time-Variant Multipath Channels Using Short Training Sequences
Wichai PONGWILAI Sawasd TANTARATANA
IEICE TRANSACTIONS on Communications
Publication Date: 2002/12/01
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
multicarrier systems, channel estimation, time-domain equalization, time-variant multipath fading channels,
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In this paper, a new approach is proposed to improve the channel estimation accuracy with channel tracking capability for adaptive multicarrier equalization systems under time-variant multipath fading channel. The improvement is carried out based on the assumption that the channel is static over a transmitted block period, and slowly linearly changing over several block periods. By applying IFFT to the concatenated channel transfer function derived from different blocks, the noise-averaging improvement is achieved, and a better estimation of the channel coefficients with some delay can be obtained. A multi-step channel predictor and a smoothing filter is utilized to compensate for the delay and make the system more robust in terms of channel tracking performance. Adaptive time domain equalization is jointly performed with this approach to avoid the channel invertibility problem found in the frequency domain approach. A short period of training sequences is utilized resulting in more efficient use of available communication capacity. The effectiveness of the proposed approach is evaluated through simulation for multicarrier systems in time-variant multipath fading channels. Results show improvement over previous channel estimation schemes.