Diplomarbeit ” Optimum training for MIMO wireless channels ”
نویسنده
چکیده
Recently, MIMO (multiple-input multiple-output) systems draw great attention because they offer high spectral efficiency and high reliability, concurrently. For exploiting those gains, channel coefficients need to be known, thus channel training is a crucial part for the performance of MIMO systems. In the first chapter, this work offers a short summary on system models for MIMO systems. The second chapter summarizes conditions on optimal training symbol design [1] and placement [2] for spatially white channels, and it shows the connection between channel capacity and training. The third chapter considers channel estimation for correlated channels. Channel correlations can be exploited in order to increase channel estimation, and thus to improve channel capacity. Conventional correlation estimators, which are used throughout the literature, are biased (e.g. [3]). Therefore, novel unbiased corrected correlation estimators are introduced. Simulations and performance discussion is provided. Finally, the corrected correlation estimators are reformulated into iterative structures, and complexity orders are investigated. Kurzfassung MIMO Systeme (Mehrfachantennensysteme) erlangten in letzter Zeit besondere Aufmerksamkeit, da sie gleichzeitig eine hohe spektrale Effizienz und Zuverlässigkeit versprechen. Um diese Eigenschaften ausnützen zu können, müssen die Kanalkoeffizienten bekannt sein, deshalb ist das Kanaltraining ein kritischer Punkt für die Leistung von MIMO Systemen. Im ersten Kapitel bietet diese Arbeit eine kurze Zusammenfassung über MIMO Systemmodelle. Das zweite Kapitel ist eine Zusammenfassung über Bedingungen für optimales Trainingssymboldesign [1] und deren Platzierung [2] für räumlich weiße Kanäle, und zeigt den Zusammenhang zwischen Kanaltraining und Kanalkapazität. Das dritte Kapitel betrachtet Kanalschätzung für korrelierte Kanäle. Korrelationen des Kanals können ausgenützt werden, um die Kanalschätzung zu verbessern, und dadurch die Kanalkapazität zu erhöhen. Herkömmliche Korrelationsschätzer, die in der Literatur verwendet werden, sind nicht erwartungstreu (z.B. [3]). Deswegen werden neue, erwartungstreue ”korrigierte Korrelationsschätzer” vorgestellt. Weitere Betrachtungen, Simulationen und Diskussion des Verhaltens der Korrelationsschätzer werden angestellt. Abschließend werden die korrigierten Korrelationsschätzer in iterative Strukturen übergeführt und die Komplexitätsordnung untersucht.
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تاریخ انتشار 2004