Stmicroelectronics N.v.

Per Ödling

Mikael Isaksson

Daniel Bengtsson

Lennart Olsson

Gunnar Bahlenberg

Magnus Johansson

Frank Sjöberg

Rickard Nilsson

Sarah Kate Wilson

Sven-Göran Ökvist

Tomas Nordström

Göran Ökvist

Zipper is the time-synchronized frequency-division duplex implementation of discrete multi-tome (DMT) modulation. Two communicating Zipper modems transmit DMT symbols simultaneously with a common clock. When all transmitters are time synchronized, the near end cross-talk (NEXT) and near end echoes injected into the received signal are orthogonal to the desired signal. The present invention provides a telecommunications transmission system using zipper and having at least two VDSL systems. Each VDSL system comprises a pair of zipper modems communicating over a cable transmission path. The telecommunications transmission system handles zipper transmission transmitted over the common cable; at least partly mitigates NEXT; and permits transmissions in a first VDSL system which are asynchronous with transmissions in a second VDSL system.

In, or relating to, VDSL

One problem, frequently encountered with VDSL transmission systems, is that upstream FEXT produced by system users having short wires can be very strong. Users having shorter wires get high bit rates whereas users having longer wires get low bit rates. In extreme cases it may happen that users with wire lengths greater than 1000 meter cannot transmit data upstream. The present invention provides a VDST transmission system with a plurality of modems. The modems are located at varying distances from a central station. There is a target bit rate for each modem. That modems on shorter wires have control means for reducing their transmit power. This reduces the FEXT produced by these modems enabling modems on longer wires to transmit at higher bit rates.

VDSL transmission systems

Growing community of inventors

Luleå, Sweden

Per Ödling