公开(公告)号：DE69718799D1

公开(公告)日：2003-03-06

申请号：DE69718799

申请日：1997-09-01

Applicant: ST MICROELECTRONICS NV

Inventor： ISAKSSON MIKAEL ,  JOHANSSON MAGNUS ,  TONVALL HARRY ,  OLSSON LENNART ,  STEFANSSON TOMAS ,  OEHMAN HANS ,  BAHLENBERG GUNNAR ,  ISAKSSON ANDERS ,  OEKVIST GOERAN ,  LJUNGGREN LIS-MARIE ,  NORDSTROEM TOMAS ,  ISAKSSON LARS-AKE ,  BENGTSSON DANIEL ,  HAKANSSON SIWERT ,  WEN YE

IPC: H04J11/00 ,  H04L1/00 ,  H04L7/033 ,  H04L27/26 ,  H04M3/00 ,  H04M11/00 ,  H04L5/06

Abstract: A multi-carrier transmission system, such as a DMT system. A receiver must be able to recover a sampling clock that is very accurately synchronized to a transmitter sampling clock. Typically, synchronization is achieved by using a reserved carrier, the pilot carrier, which is transmitted with a fixed phase. The receiver sampling clock is then phase locked to the pilot carrier. Frame timing can be recovered by using a correlation technique. Thus an improved method of recovering a sample clock and phase locking the sampling clock to a pilot carrier is provided.

公开(公告)号：DE69717285D1

公开(公告)日：2003-01-02

申请号：DE69717285

申请日：1997-09-01

Applicant: ST MICROELECTRONICS NV

Inventor： ISAKSSON MIKAEL ,  JOHANSSON MAGNUS ,  TONVALL HARRY ,  OLSSON LENNART ,  STEFANSSON TOMAS ,  OEHMAN HANS ,  BAHLENBERG GUNNAR ,  ISAKSSON ANDERS ,  OEKVIST GOERAN ,  LJUNGGREN LIS-MARIE ,  NORDSTROEM TOMAS ,  ISAKSSON LARS-AKE ,  BENGTSSON DANIEL ,  HAKANSSON SIWERT ,  WEN YE

IPC: H04L27/34 ,  H04J11/00 ,  H04L1/00 ,  H04L27/26 ,  H04M3/00 ,  H04M11/00 ,  H04L5/06

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/sigma2, where d is the shortest distance between neighboring constellations, sigma is a standard deviation and sigma2 is the variance of the deviations of the input and output signal values of the symbol detection unit.

公开(公告)号：AT227912T

公开(公告)日：2002-11-15

申请号：AT97937936

申请日：1997-09-01

Applicant: ST MICROELECTRONICS NV

Inventor： ISAKSSON MIKAEL ,  JOHANSSON MAGNUS ,  TONVALL HARRY ,  OLSSON LENNART ,  STEFANSSON TOMAS ,  OEHMAN HANS ,  BAHLENBERG GUNNAR ,  ISAKSSON ANDERS ,  OEKVIST GOERAN ,  LJUNGGREN LIS-MARIE ,  NORDSTROEM TOMAS ,  ISAKSSON LARS-AKE ,  BENGTSSON DANIEL ,  HAEKANSSON SIWERT ,  WEN YE

IPC: H04L27/34 ,  H04J11/00 ,  H04L1/00 ,  H04L7/027 ,  H04L27/26 ,  H04M3/00 ,  H04M11/00 ,  H04L5/06

Abstract: A two-way multi-carrier transmission system, such as a DMT system. If there are dynamic changes in the transmission parameters, synchronization must be maintained between the transmitter and the receiver when the transmission parameters changed. The first stage of such a process requires that the changes of parameter be notified by one transceiver to others involved in an active communication process over a slow transmission channel such as the control channel. Subsequently, the synchronization transceiver is adjusted simultaneously, i.e., from a predetermined DMT symbol. Such adjustments in time synchronization must be achieved with a minimum of overhead.