The Discrete Cosine Multitone Modulation Modem Construction and Functionality

J. Danda, K. Loziak, M. Sikora, and R. Watza (Poland)


Multicarier modulation, DCT, DFT, DCMT, OFDM


Communication networks require effective, high speed data transmission over long distances. This efficiency should encompass user and network operator requirements, especially bandwidth utilization and high immunity to the channel noise. The key aspect in the process of the signal transmission is effective signal modulation, when copper unshielded wires are used. For many years DMT modulation has been analysed and demonstrated its benefits. The ANSI adopted the DMT technique to its DSL standard and many manufactures implement it in xDSL modems over twisted pair of wires. In an early papers, researches proposed Discrete Fourier Transform (DFT) in order to provide high robustness with regard to the channel noise. However this transformation requires two-dimensional, complex encoders. The problem might be overcome by one-dimensional binary to-real encoders. Our approach is to implement a new modulation technique, called DCMT, and to compare its efficiency with well known DMT. In this paper implementation of the DCMT modem and simulation results are presented.

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