Authors:
Andreas Ahrens
and
Christoph Lange
Affiliation:
Institute of Communications Engineering, University of Rostock, Germany
Keyword(s):
Twisted-pair Cable, OFDM, Power Allocation, Multiple-Input Multiple-Output System, Lagrange Multiplier Method, Singular-Value Decomposition.
Related
Ontology
Subjects/Areas/Topics:
Multidimensional Signal Processing
;
Multimedia
;
Multimedia Signal Processing
;
Telecommunications
Abstract:
Crosstalk between neighbouring wire pairs is one of the major impairments in digital transmission via multipair copper cables, which essentially limits the transmission quality and the throughput of such cables. For high-rate transmission, often the strong near-end crosstalk (NEXT) disturbance is avoided or suppressed and only the far-end crosstalk (FEXT) remains as crosstalk influence. If FEXT is present, signal parts are trans- mitted via the FEXT paths from the transmitter to the receiver in addition to the direct transmission paths. Therefore transmission schemes are of great practical interest, which take advantage of the signal parts transmitted via the FEXT paths. Here a SVD (singular-value decomposition) equalized MIMO-OFDM system is investigated, which is able to take advantage of the FEXT signal path. Based on the Lagrange multiplier method an optimal power allocation schema is considered in order to reduce the overall bit-error rate at a fixed data rate and fixed QAM const
ellation sizes. Thereby an interesting combination of SVD equalization and power allocation is considered, where the transmit power is not only adapted to the subchannels but rather to the symbol amplitudes of the SVD equalized data block. As a result it can be seen that the exploitation of FEXT is important for wireline transmission systems in particular with high couplings between neighbouring wire pairs and the power allocation is possible taking the different subcarriers into account.
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