Orthogonal Space-Time Spreading Transmit Diversity

Shinsuke TAKAOKA  Fumiyuki ADACHI  

IEICE TRANSACTIONS on Communications   Vol.E88-B   No.5   pp.2120-2127
Publication Date: 2005/05/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.5.2120
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
transmit diversity,  space-time spreading,  fading channel,  

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In this paper, a new 2-antenna transmit diversity, called orthogonal space-time spreading transmit diversity (OSTSTD) combined with delay transmission, is proposed. At the transmitter, N data symbols to be transmitted are spread using N different orthogonal space-time spreading codes (each represented by NN matrix) and are transmitted from two transmit antennas after adding different time delays. At the receiver, 2-step space-time despreading is carried out to recover the N transmitted data symbols. The first step recovers the N orthogonal spatial channels by taking the correlation between the received space-time spread signal and the time-domain spreading codes. The second step recovers the N transmitted data symbols using minimum mean square error (MMSE) despreading. The average bit error rate (BER) performance in a Rayleigh fading channel is evaluated by computer simulation. It is confirmed that the OSTSTD provides better BER performance than the Alamouti's space-time transmit diversity (STTD) at the cost of transmission time delay.