A New OFDM Transmission Scheme Using DFT Code Multiplexing

Seong Keun OH
Myung Hoon SUNWOO

IEICE TRANSACTIONS on Communications   Vol.E87-B    No.3    pp.760-763
Publication Date: 2004/03/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Wireless Communication Technology
OFDM,  DFT code multiplexing,  distributed transmission,  PAR,  

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We propose a new orthogonal frequency division multiplexing transmission scheme using orthogonal code multiplexing. This scheme makes all modulation symbols have the same reliability even in a frequency selective fading channel, through a distributed transmission of each symbol over the whole effective subcarriers using a distinct orthogonal code. As an appropriate set of orthogonal multiplexing codes, we use the set of discrete Fourier transform code sequences that hold the orthogonality irrespective of the length. Using this set, we also can greatly reduce the peak-to-average-power ratio (PAR) of the resulting signal. Simulation results show that the proposed scheme can significantly reduce the required signal-to-noise ratio at a given bit error rate over the existing schemes. The scheme can maintain the PAR within a reasonable range of about 6 dB even up to 512 subcarriers and works well even with PAR clipping of 1.5 dB.