Digital modulation using QAM with multiple signal point constell

Pulse or digital communications – Systems using alternating or pulsating current – Plural channels for transmission of a single pulse train

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375269, 375272, 375273, 375281, 371 43, 332100, 332103, 341 83, 341174, H04K 110, H03M 702, H04L 1702

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055984355

ABSTRACT:
Data are transmitted using multiple carriers modulated by quadrature amplitude modulation. In general, the carriers carry different numbers of bits, to exploit the fact that the properties of a transmission path are more favorable to carriers at some frequencies than to those at others. The bit allocation process is made closer to optimum by permitting allocation of a non-integer number of bits to a carrier. Input bits are grouped for several carriers and this binary representation is converted to a number representation in which the base of each digit corresponds to the number of points in the QAM constellation for a respective carrier (or to this number divided by a power of two).

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