A New OFDM Demodulation Method with Variable-Length Effective Symbol and ICI Canceller

Noriyoshi SUZUKI  Hideyuki UEHARA  Mitsuo YOKOYAMA  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E85-A   No.12   pp.2859-2867
Publication Date: 2002/12/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Spread Spectrum Techniques and Applications)
Category: 
Keyword: 
multi-carrier modulation,  orthogonal frequency division multiplexing (OFDM),  multipath fading,  ICI canceller,  guard interval,  

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Summary: 
In an orthogonal frequency division multiplexing (OFDM) system, the bit error performance is degraded in the presence of multiple propagation paths whose excess delays are longer than the Guard Interval (GI), because the orthogonality between subcarriers cannot be maintained. In this paper, we propose a new OFDM demodulation method with a variable-length effective symbol and a multi-stage inter-carrier interference (ICI) canceller, in order to improve the bit error performance in the presence of multipaths whose excess delays are longer than the GI. The influence of the inter-symbol interference (ISI) is eliminated by the variable-length effective symbol, and then the ICI component is reduced by the multi-stage ICI canceller. The principle of the proposed method is explained, and the performance of the proposed method is then evaluated by computer simulation. The results show that the proposed method improves the system availability under more various multipath fading environments without changing the system parameters.