Reliability-Based Cross-Layer Design of Digital Transmission Systems

In dieser Arbeit werden schichtübergreifende Ansätze ausgehend von der untersten, der physikalische Schicht, betrachtet. Dafür werden die weichen Ausgangswerte des üblicherweise als letzte Komponente der physikalischen Schicht angeordneten Kanaldecodierers verwendet, um die Bit- oder die Wortfehlerwahrscheinlichkeit zu berechnen. Mit der Bit- bzw. Wortfehlerwahrscheinlichkeit steht ein Maß zur Schätzung der Übertragungsqualität zur Verfügung, das schichtübergreifend genutzt werden kann. Ein großer Vorteil dieser Vorgehensweise die Fehlerwahrscheinlichkeit zu berechnen ist ihre Unabhängigkeit von Kanal, Modulationsformat und verwendetem Kanalcode. Zugleich gedruckt erschienen im Shaker Verlag GmbH Aachen.In this thesis, cross-layer approaches based on the lowest layer of the protocol stack, the physical layer, are considered. Towards that goal, the soft output of the last component of the physical layer, the channel decoder, is used to calculate the bit or word error probability. The bit or word error probability is a measure of the transmission quality which can be applied in a cross-layer design. An advantage of this approach to calculate the error probability is its independence of channel, modulation format, and applied channel code. Also available in print from Shaker Verlag, Aachen, Germany

Reliability-based Packet Combining with Application to Interleave-division Multiple Access

In this paper we investigate hybrid automatic repeat request (HARQ) schemes based on soft outputs of a channel decoder. Focus is on adaptive interleave-division multiple access (IDMA) transmission. Such a system is able to provide virtually arbitrary bit error rates. However, the adaptation has to be supported by the automatic repeat request (ARQ) scheme used for error control. The proposed HARQ schemes use the reliability information provided by the channel decoder to decide whether a packet satisfies the quality of service (QoS) requirements in terms of a maximum bit error rate. No additional error detection code is applied. Furthermore, packet combining schemes also employing the reliability information are proposed and their performance is simulated for an IDMA-based transmission system

Reliability-based Packet Combining with Application to Interleave-division Multiple Access

In this paper we investigate hybrid automatic repeat request (HARQ) schemes based on soft outputs of a channel decoder. Focus is on adaptive interleave-division multiple access (IDMA) transmission. Such a system is able to provide virtually arbitrary bit error rates. However, the adaptation has to be supported by the automatic repeat request (ARQ) scheme used for error control. The proposed HARQ schemes use the reliability information provided by the channel decoder to decide whether a packet satisfies the quality of service (QoS) requirements in terms of a maximum bit error rate. No additional error detection code is applied. Furthermore, packet combining schemes also employing the reliability information are proposed and their performance is simulated for an IDMA-based transmission system