8ARQ Systems forWireless CommunicationsDem FachbereichElektrotechnik und Informationstechnikder Technischen Universität Darmstadtzur Erlangung der Würde einesDoktor Ingenieurs (Dr. Ing.)vorgelegte und genehmigteDissertationvonMichael Philipp Schmitt M.S. SUNY/Buffalogeboren am 28. Januar 1972 in AschaffenburgReferent: Prof. Dr. Ing. B. DorschKorreferent: Prof. Dr. Ing. R. JakobyTag der Einreichung: 15. Juni 2002Tag der mündlichen Prüfung: 26. September 2002D17Darmstädter DissertationDarmstadt 2002To my motherAgnes Schmittandto the memory of my fatherAlfred SchmittAcknowledgementsWritting a dissertation takes its time. Many hours are involved - including those which had to beborrowed from my private life. Therefore, I want to take the opportunity to thank my family, myfriends, and, of course, Heidi for their patience and their support throughout the years.But time is not all it takes. The ideas which led to this work grew from many interactions.Therefore, I would like to thank my former colleagues at Panasonic European Laboratories, Lan gen Germany, especially Christian Wengerter and Thomas Wiebke. Many ideas, which influencedthis work considerably, originated from our collaboration. Also, I would like to thank Dr. Jagath Kumara who made my stay at the Department of Electrical Engineering at Massey University,Palmerston North, New Zealand possible. Large parts of this work were written in the comfort able atmosphere, he provided.