Distributed information-lossless space-time codes for amplify-and-forward TH-UWB systems

In this paper, we extend the non-orthogonal amplify-and-forward (NAF) cooperative scheme to the context of impulse radio ultra-wideband (UWB) systems. In particular, we consider the problem of distributed space-time (ST) coding with 2D pulse position modulations (PPM) and joint pulse position and amplitude modulations (PPAM) and we propose the first known family of full-rate codes that are information-lossless with these constellations. Being totally-real, these codes are adapted to the carrier-less nature of the UWB transmissions and they outperform all previously known totally- real constructions with any number of relays. With binary PPM, they satisfy all the construction constraints of the optimal complex-valued codes proposed in [S. Yang and J.-C. Belfore, 2007] as well as the additional constraint of being real-valued.