JultikaUniversity of Oulu repository

Abstract

The THz band is now becoming the core interest for many researchers as it offers massive bandwidth and high transmission rates. It is expected to be a solution to ongoing spectrum scarcity in the wireless communication world. Wave propagating through a channel is affected by various phenomena, especially in the case of non-line-of-sight (NLOS) condition. In this thesis work, measurement results on several NLOS propagation mechanisms such as reflection, diffraction, and penetration have been reported in the terahertz band ranging from 0.1 THz to 3 THz. Here, the primary focus is to measure the possible NLOS multipath, such as reflected, diffracted, and penetrated paths or a combination of multiple NLOS components. The goal is to evaluate and analyze the feasibility of those multipath in order to estimate the possibility to establish a communication link via such paths.

The measurements have been conducted by using TeraView TeraPulse 4000, a measurement device that is based on THz time-domain spectroscopy (THz-TDS). Measurements were made under various NLOS propagation scenarios with several common indoor materials. Characteristics of the measured materials have also been reported. The results have been given as a function of frequency and measurement angles.

Corresponding background theories and comparisons with the measurement results have also been investigated with subsequent analysis to check the relevance of the measurement results. The idea was to find possible multipath signals after various NLOS events while traveling through a channel and behavioural changes of the transmitted signal with the change of measurement scenarios. The measurement results agreed with the corresponding theories as expected. The THz band offers overall a decent NLOS wireless communication link between the receiver and transmitter at the lower angles.