Space-Time Cyclic Delay Transmit Diversity for a Multi-Code DS-CDMA Signal with Frequency-Domain Equalization

Frequency-domain equalization (FDE) can take advantage of the frequency-selectivity of the channel to improve the transmission performance in a frequency selective fading channel. To further improve the transmission performance, the transmit diversity technique can be used. Cyclic delay transmit diversity (CDTD) can strengthen the frequencyselectivity while space-time transmit diversity (STTD) can achieve the antenna diversity gain. In this paper, we propose a 4-antenna space-time cyclic delay transmit diversity (STCDTD), which is a combination of 2antenna STTD and 2-antenna CDTD schemes, for orthogonal multi-code direct sequence code division multiple access (DS-CDMA) using FDE. We evaluate the BER performance and the throughput performance by computer simulation and compare them with the original CDTD and STTD schemes. key words: multi-code DS-CDMA, Frequency-domain equalization, Cyclic Delay Transmit Diversity (CDTD), Space-Time Transmit Diversity (STTD)