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Space-Code Transmit Diversity for OFDM-CDM Systems
IEICE TRANSACTIONS on Communications
Publication Date: 2003/12/01
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Software Defined Radio Technology and Its Applications)
OFDM-CDM, transmit diversity (TD), space-time block code, Doppler spread,
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This paper presents a transmit diversity scheme that uses space-time block codes (STBC) in space-spreading code dimensions for time-direction spreading or two-dimensional spreading orthogonal frequency-division multiplexing code-division multiplexing (OFDM-CDM) downlink transmission. The STBC output symbols in two adjacent time slots are spread by two distinctive spreading codes and multiplexed in the same spreading segment. At a receiver, the received subcarrier signals are despread with the two spreading codes in the direction of time, space-time decoded, and then combined in the direction of frequency. Simulation results demonstrated that the proposed scheme provided high tolerance to Doppler spread and outperformed space-time transmit diversity (STTD) for high-mobility users.