Background Space-time block coding has emerged as an efficient means of achieving near optimal transmitter diversity gain [Alamouti 98, Tarokh 99 Existing implementations are sensitive to delay spreads and, therefore, are limited to flat fading environments such as indoor wireless networks Orthogonal frequency division multiplexing (OF DM) With a sufficiently long cyclic prefix can convert frequency-selective fading channels into multiple flat fading subchannels Combine space-time block code and OFDM Georgia Institute of Technology Center for Signal and Image ProcessingGeorgia Institute of Technology Center for Signal and Image Processing Background • Space-time block coding has emerged as an efficient means of achieving near optimal transmitter diversity gain [Alamouti 98,Tarokh 99]. • Existing implementations are sensitive to delay spreads and, therefore, are limited to flat fading environments, such as indoor wireless networks. • Orthogonal frequency division multiplexing (OFDM) with a sufficiently long cyclic prefix can convert frequency-selective fading channels into multiple flat fading subchannels. Combine space-time block code and OFDM