Prof. Dr.-Ing. Werner Henkel
All the work in this bachelors thesis is focused on investigating channel reciprocity in powerlines, i.e. performing measurements, which determine channel properties as seen from both the transmitting and receiving side, followed by a comparison and analysis of results. This study is part of a broader research topic in the Physical-layer security field. There have been great developments and significant improvements in wireless networks, without drawing much attention to wireline transmission, since until recently it was considered too deterministic. However, the new idea for developing key generation and reconciliation techniques based on the FEXT random transfer function present in different types of cables draws interest to physical-layer security in wireline communication. In order for the FEXT coupling function to serve as a basis for key generation, the channel is required to be almost reciprocal, which is tested for powerlines in this thesis. Measuring in an active network requires suitable powerline connectors, which ensure halfway matching impedances with the characteristic impedance of the line and, most importantly, fulfill safety requirements. Therefore, the whole design process is carried out step by step using the software Eagle 7.5.0, by first drawing the schematics for the transmitter, receiver and termination and then converting to the corresponding boards to be printed and assembled. The next step is the simulation of the complete designed network making sure that the component values are chosen correctly and giving an idea of how the whole system is expected to behave. After the implementation of the printed circuit boards, assembled in their specified safety housing, the measurement campaign takes place. There are two sets of measurements, which are performed in three different power outlets. Two of them stand for the channel under study and the third one acts as an illegitimate user. The results of the measurements are then analyzed and evaluated, as well as compared with initial expectations and preliminary measurements on a plain non-installed power cable.