Excitation Signal Design for THz Channel Sounding and Propagation Parameter Estimation

In this publication, we analyze how the performance of propagation parameter estimation for THz channel sounding can be improved by the power spectrum design of a multicarrier waveform. To this end, we discuss the Fisher information of the propagation parameters and the corresponding deterministic Cramèr-Rao lower bound (CRB) as well as their relation to the carrier powers of the excitation signal. We use these quantities to design waveforms that improve range estimation. In practice, evaluating the Fisher information requires prior knowledge of the propagation scenario which is usually unavailable. Hence, we propose two solutions which we compare numerically to the classical approach of equal power distribution. The evaluation shows that an optimized power distribution can improve the CRB comparable up to a 4 dB gain in signal-to-noise ratio (SNR) if knowledge about the propagation scenario is available and slightly less if the scenario is unknown.