Distance Estimation Under Molecular Absorption Delay in THz Frequency Band

In this letter, we propose a distance estimation method that accounts for molecular absorption (MA) delay in the THz frequency band. In radio propagation, the time of arrival (TOA) at the receiver from the transmitter is typically determined by the propagation delay, which is the distance divided by the speed of light in a line-of-sight (LoS) scenario. However, in THz the observable TOA could exceed the propagation delay due to an additional delay denoted by MA delay caused by molecular absorption. This MA delay introduces a biased estimate into conventional distance estimations. In this letter, a novel distance estimation method based on TOA incorporating MA delay is proposed. Numerical evaluations indicate that our proposed distance estimation method outperforms the conventional approach by accounting for the effects of MA delay.