Inter-Symbol Interference Suppression Scheme Using Even-Numbered Sub-Carriers for Fixed-Rate OFDM Systems

Fumiaki MAEHARA  Fumihito SASAMORI  Fumio TAKAHATA  

IEICE TRANSACTIONS on Communications   Vol.E87-B   No.4   pp.866-872
Publication Date: 2004/04/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
OFDM,  multipath delay,  inter-symbol interference,  even-numbered sub-carrier,  guard interval,  

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This paper proposes an inter-symbol interference (ISI) suppression scheme using only the even-numbered sub-carriers for the fixed-rate OFDM systems with the 2-dimensional modulation. The proposed scheme is based on the principle that the first half of the waveform in the time domain is the same as the second half when an OFDM symbol is composed of only the even-numbered sub-carriers. The feature of the proposed scheme is that, in the case of the maximum multipath delay beyond the duration of the guard interval, the OFDM symbol with only the even-numbered sub-carriers is transmitted in order to generate the extended virtual guard interval and that the high-level modulation with the sub-carrier power enhancement is applied to achieve the constant data rate. In addition, at the receiver, only the second half of the OFDM symbol is used for the FFT processing to avoid the ISI. Moreover, the condition of the maximum multipath delay is notified to the transmitter by using the feedback channel. Numerical results given by computer simulation showed that the proposed scheme provides far better bit error rate (BER) performance than the traditional OFDM transmission using all sub-carriers under the multipath delay beyond the duration of the guard interval.