| Broadband wireless communications must cope with critical performance-limiting challenges that include multiuser interference (MUI), time- and frequency-selective fading channels, as well as power and bandwidth constraints. Space-time (ST) coding offers an effective transmit-antenna diversity technique to combat fading. However, most existing works have focused on flat fading channels—an assumption not valid for broadband transmissions, and they are ineffective in the presence of MUI. To address the limitations of existing ST coding schemes, this thesis: (i) designs ST block coding that guarantees symbol recovery and diversity gains in frequency selective fading channels; (ii) derives double differential ST encoders/decoders to cope with carrier offsets induced time-selective effects, and thereby enables diversity gains without channel status information at the receiver; (iii) incorporates Kalman filtering for channel tracking in order to enable ST decoding with diversity gains in time selective channels; and (vi) applies ST coding to multiple access over frequency-selective fading channels. Our research on ST coding offers the potential for enhanced performance, capacity and high speed delivery of information in broadband wireless communication systems. The ultimate goal is to have wireless services such as mobile computing, high-speed internet access, and other personal communication services delivered with improved quality of service and be accessible to more people. |
