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Master Thesis

Synchronisation rapide des systèmes de communication QAM à haut niveau dans des conditions de canal avec échos

Abstract : Modern communication systems use modulations with high spectral efficiency to transmit information over limited bandwidth channels. Thus, quadrature amplitude modulation (QAM) is widely used but requires accurate synchronization between transmitter and receiver oscillators. High order QAM and transmission without pilot signal increase the complexity of this operation and specific algorithms were developed to correct large carrier frequency and phase offsets. On the other hand, the performances of these algorithms decrease when echoes occurs in the channel. Use of an equalizer with an adaptive algorithm is then necessary to correct intersymbols interferences. When distortions, frequency offset and modulation level become important, a joint architecture is mandatory to allow carrier recovery and adaptive equalization algorithms to collaborate and work efficiently. This five chapter thesis first deals with some theoretical aspects, define the problem to be addressed set boundaries of the study. Then, a specific QAM carrier recovery algorithm is presented in detail. The goal of third chapter is to analyze its performances with the Rummler channel model. Then, some joint carrier recovery and equalization solutions are presented. Finally, from these analyses, an architecture and an initialization procedure are proposed: simulation results show good performances in a multipath channel for 64 and 256-QAM.
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Master Thesis
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Submitted on : Monday, March 7, 2011 - 3:11:42 PM
Last modification on : Saturday, February 8, 2020 - 11:52:02 AM
Long-term archiving on: : Wednesday, June 8, 2011 - 6:44:31 AM

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  • HAL Id : dumas-00574237, version 1

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Yves Gadé. Synchronisation rapide des systèmes de communication QAM à haut niveau dans des conditions de canal avec échos. Electronique. 2011. ⟨dumas-00574237⟩

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