Radijo bangų difrakcijos ir spindulių trasavimo metodų palyginimas urbanizuotose vietovėse /

Telecommunication is a key element of modern civilization, and we can find applications of it in every sphere. Most of the world has and uses a mobile telecommunication device, for example a smartphone, which can send and receive information packets through radio waves. Telecommunication systems require thoughtful planning since the environment between the transmitter and receiver strongly influences the signal: that could be the distance traveled, obstacles like buildings, trees that can block direct line of sight. All these aspects require consideration when setting up telecommunication systems for consumers. One of the factors that determines the signal strength is diffraction, but there is no universal way of predicting losses due to diffraction. The most accurate method is ray tracing, but it is very sensitive to geometry errors and has a slow calculation process, therefore other algorithms are being developed and improved. A paper released in 2021 suggests a method of predicting multiple diffraction losses over buildings [9]. Another new paper released in 2024 shows a method of calculating diffraction losses over vehicles [8]. Methods used in this paper are: single knife edge diffraction, Bullington diffraction, Deygout diffraction, Geometrical theory of diffraction, Uniform theory of diffraction and the modern ray tracing technique which has its roots in graphical processing. The aim of this work is to compare various, over the rooftop radio diffraction loss prediction methods, while using real life geometry data. Furthermore, the secondary aim is to compare diffraction loss algorithm results with ray tracing results. Single diffraction calculations were performed on a single knife obstacle using single knife edge and uniform theory of diffraction and it was found that the results vary from 5-10 dB. Diffraction loss estimation and ray tracing calculations were performed on Kaunas city OSM geometrical data, and it was found that all the methods predict similar losses (in the range of 10 dB) when there is a small number of obstacles. When we introduce more obstacles, the prediction results start to differ. Uniform theory of diffraction and ray tracing give the most optimistic results, meanwhile Deygout and Bullington results are identical when a small number of obstacles is present. The results suggest that from a practical standpoint, when calculating diffraction losses for a single obstacle, the quick single knife edge diffraction calculation can be performed instead of the slow Uniform theory of diffraction calculation without much accuracy loss. The simpler Bullington algorithm can be used over the more complex Deygout method when calculating diffraction losses over multi – obstacle profiles since their results are almost identical, when there are 4 or less obstacles present. Furthermore, the CCDF results of this work suggest that Uniform theory of diffraction can be used instead of ray tracing for faster calculations without sacrificing accuracy.

Grantor dc:publisher

Institutional Repository of Vilnius University

Year dc:date

2024

Author dc:creator

• Anufrijevas, Benas,

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

lit

Repository record dc:identifier

https://repository.vu.lt/VU:ELABAETD210578683&prefLang=en_US

OAI identifier oai:identifier

oai:vu.lt:elaba:210578683