Multicarrier Modulation with the Discrete Cosine Transform

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


Multicarrier modulation, DCT, DFT, DCMT, OFDM


Multicarrier modulation is a data transmission technique based on data stream partitioning into a number of substreams, each transmitted over a separate frequency channel. It is known, that one of the most important advantages of a multicarrier modulation is it's negligible sensitivity to the narrowband noise and high spectral efficiency. A high computational complexity is the main disadvantage of multicarrier modulation. In 1971 Weinstein and Ebert proposed that the Discrete Fourier Transform (DFT) could be used for modulation and demodulation in a multicarrier mode [1]. All contemporary digital modems, including common modems with Orthogonal Frequency Division Multiplexing (OFDM, also known as Discrete Multitone Modulation, DMT) apply orthogonal transforms, typically DFT. The use of DFT implies application of two-dimensional, complex encoders. In this paper another implementation of multicarrier modulation, based on the one-dimensional Discrete Cosine Transform (DCT) is going to be presented. It can be denoted as DCMT (Discrete Cosine Multitone Modulation). The binary-to-real encoder is used for DCMT, similarly as for Overlapped Discrete Multitone Modulation (ODMM) developed by Saandberg and Tzannes in 1995 [1].

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