This thesis is submitted for the degree of Master of Science at the Korea University. 
All of the work presented henceforth has been conducted in the \textit{Lab for Informatics, Communications, and Systems} at the Korea University, under the supervision of professor Sang Hyun Lee. The research described herein was conducted under the supervision of professor Sang Hyun Lee, between October 1998 and October 2001.
It is to the best of my knowledge original, except where acknowledgments and references are made to previous work.

Part of this thesis has been submitted as a conference paper and accepted for presentation in IEEE GLOBECOM 2022 Workshops.
The corresponding information is as follows :\\% publication in the corresponding proceedings

S. Kim, H. K. Kim, and S. H. Lee, ``Survey Propagation for Cell-Free Massive MIMO Pilot Assignment,'' in {\em Proc. IEEE Globecom Workshops (GC Wkshps), Rio de Janeiro, Brazil, Dec. 2022}, in press.\\

While the project has been performed by my lead, there have been thankful contributions from several intellectuals. % responsible for the problem formulation, computational design of algorithm, major areas of concept formation, data collection and analysis, as well as manuscript composition.
Professor Sang Hyun Lee is the supervisory author of the paper and has been involved throughout the project. 
His insights and knowledge have motivated to employ a physical approach in this work.
Hong Ki Kim has organized a simulation environment for the demonstration of our algorithm, and co-worked on manuscript edits and proofreading. Hong Ki Kim established a simulation environment for the verification of our proposed algorithm, and then worked together on editing and reviewing the manuscript.
I sincerely appreciate their true support.