Performance analysis of space-time coding over ultra wideband channels

In this paper, we propose two transmit diversity schemes for ultra-wideband time-hopping (UWB-TH) communications. The performance of these schemes is evaluated for binary antipodal signalling over real UWB channels. The first proposed scheme assigns orthogonal codes to the M transmit antennas and is capable of achieving the maximum transmit diversity of M with no data rate loss compared to single antenna UWB systems. The second scheme is the extension of Alamouti's space-time (ST) code to UWB communications. Simulations and semi-analytical evaluations of the error probability show that giving rise to both spatial and multipath diversity by associating these schemes with partial or selective combining Rake receivers (PRake or SRake) can result in considerable performance gains.