Optimum sequence design and performance evaluation of channel estimation techniques for ultra-wideband systems

Unstructured approaches for the estimation of ultra-wideband (UWB) channels are investigated, namely optimal maximum likelihood (ML) estimation, suboptimal least squares (LS) estimation, and the so-called pilot symbol assisted modulation (PSAM) estimation techniques. Moreover, closed form expressions for the maximum likelihood for a UWB system and an optimum sequence design technique for the LS scheme are derived. Performance analysis in terms of the minimum squared error (MSE) and accuracy in terms of the Cramer-Rao lower bound (CRLB) are provided. The trade-off between performance and complexity is shown for each reported estimation technique.