Adaptive Modulated OFDM Radio Transmission Scheme Using a New Channel Estimation Method for Future Broadband Mobile Communication Systems

Hiroshi HARADA
Yukiyoshi KAMIO
Masayuki FUJISE

IEICE TRANSACTIONS on Communications   Vol.E85-B    No.12    pp.2785-2796
Publication Date: 2002/12/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
OFDM,  adaptive modulation,  C/N0,  FEC,  delay spread,  

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An adaptive modulated orthogonal frequency division multiplexing (OFDM) radio transmission scheme that enables efficient data transmission in multipath fading environments is newly proposed. This scheme can be used in standardized multimedia mobile access systems such as ETSI-BRAN, and ARIB-MMAC. It is based on estimating the delay spread and the carrier-to-noise power density ratio (C/N0). The estimation is done using channel estimation symbols that are inserted into the frames of the standard OFDM radio transmission scheme. Computer simulations show that the estimation method results in an average BER close to those when propagation characteristics are perfectly estimated. Furthermore, when the adaptive OFDM transmission scheme is based on BPSK, QPSK or 16 QAM, the average BER is almost close to that when BPSK-OFDM is only used, and the average transmission rate is 1.8 times as high. Using an error-correction code based on convolutional code results in an average BER lower than that with the BPSK- and QPSK-OFDM schemes.