Abstract: In this paper, w e inv estigate the impact of imperfect cha nnel estimation and correlated Na kagami fading channels o n th e perfo rmance of STTD( space-time tr nasmi t div ersi ty) ca reful ly. Fi rst ly, o n the assumption o f channel estimatio n erro r wi th Gaussian dist ributio n, the sig nal to noi se ratio at the receiv ers i s analyzed.Previous w ork on performa nce analysis of ST TD has been rest ricted to unco rrelated Rayleig h fading. In this paper, w e deriv e a closed-fo rm bit erro r probability ( BER) ex pression fo r S TTD wi th tw o t ransmi t antennas and arbi trary number of receiv eantennas under co rrela ted Nakagami fading channels wi th arbi trary co rrela tion v ariance mat rix. Finally, numerical result s from simulations are given to suppo rt the mathematical dev elopment of the BER expression, and show n that there is af loor for BER at high SN Ras the cha nnel estimation erro r to channel gain ra tio ( EGR) increases. We found that the speed fo r BER performa nce deg rada tion decreases fai rly slow ly when EGR < - 15 dB, and the ef fect of the cha nnel correlatio n i s not sig ni ficant for co rrela tio n coef ficient around 0. 4. The ef fect of fading pa rameterm of Nakagami dist ributio n on the performa nce of STTD i s al so discussed.

Key words: space-time transmit diversity, channel estimation, Nakagami fading, fading correlation, bit error ratio