Multi-carrier transmission systems

US6438174B1 · kind B1 · utility

Assignee

• STMICROELECTRONICS N.V. · NL

Inventors

• Mikael Isaksson · Luleå, SE
• Magnus Johansson · Luleå, SE
• Harry Tonvall · Luleå, SE
• Lennart Olsson · Luleå, SE
• Tomas Stefansson · Luleå, SE
• Hans Ohman · Luleå, SE
• Gunnar Bahlenberg · Luleå, SE
• Anders Isaksson · Luleå, SE
• Goran Okvist · Luleå, SE
• Lis-Marie Ljunggren · Luleå, SE
• Tomas Nordstrom · Luleå, SE
• Lars-Ake Isaksson · Luleå, SE
• Daniel Bengtsson · Luleå, SE
• Siwert Hakansson · Luleå, SE
• Ye Wen · Luleå, SE

Key dates

• Filing date: Jun 4, 1999
• Grant date: Aug 20, 2002
• Expiry date: Jun 4, 2019

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L1/0071
• WIPO field: Digital communication
• WIPO sector: Electrical engineering

Abstract

A multi-carrier transmission system such as a DMT based VDSL system. The system uses orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol. This estimate includes digital receiver and transmitter units with the receiver unit including a symbol detection unit. This system is adapted to determine a parameter for each single carrier with the parameter being indicative of a deviation of a received signal from a corresponding constellation point. It compares the parameter with an upper lower limit and if the parameter is outside the limits, changes the constellation used to modulate the carrier to a neighboring constellation. The symbol detection unit may be used to determine a parameter such as the ratio d2/&sgr;2, where d is the shortest distance between neighboring constellations, &sgr; is a standard deviation and &sgr;2 is the variance of the deviations of the input and output signal values of the symbol detection unit.