Analog space-time coding for multiantenna ultra-wideband transmissions

Ultra-wideband (UWB) transmissions have well-documented advantages for low-power, peer-to-peer, and multiple-access communications. Space-time coding (STC), on the other hand, has gained popularity as an effective means of boosting rates and performance. Existing UWB transmitters rely on a single antenna, while ST coders have mostly focused on digital linearly modulated transmissions. In this paper, we develop ST codes for analog (and possibly nonlinearly) modulated multiantenna UWB systems. We show that the resulting analog system is able to collect not only the spatial diversity, but also the multipath diversity inherited by the dense multipath channel, with either coherent or noncoherent reception. Simulations confirm a considerable increase in both bit-error rate performance and immunity against timing jitter, when wedding STC with UWB transmissions.