Multi-carrier transmission systems

• US 6,359,926 B1
• Filed: 06/01/1999
• Issued: 03/19/2002
• Est. Priority Date: 09/02/1996
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: STMicroelectronics NV
• Inventors: Okvist, Goran, Ljunggren, Lis-Marie, Isaksson, Mikael, Nordstrom, Tomas, Johansson, Magnus, Isaksson, Lars-Ake, Tonvall, Harry, Bengtsson, Daniel, Olsson, Lennart, Hakansson, Siwert, Stefansson, Tomas, Wen, Ye, Ohman, Hans, Bahlenberg, Gunnar, Isaksson, Anders
• Primary Examiner(s): Le, Amanda T.
• Application Number:
  US09/147,748
• Time in Patent Office: 1,022 Days
• Field of Search: 375/219, 375/260, 375/356, 375/362, 370/480
• US Class Current: 375/219
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols

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.

Claims

1. A receiver, for use with a multi-carrier transmission system using orthogonal carriers, in which a receiver sampling clock is synchronized with a transmitter sampling clock by extracting timing data from a pilot carrier on which a known sequence of symbols is transmitted, characterised in that said receiver includes control channel means for receiving a control channel over which data relating to changes in dynamic transmission parameters is transmitted and correlation means for extracting timing data from said pilot carrier and uniquely identifying a symbol at which a change in said dynamic transmission parameters will be effected.

2. A receiver, as claimed in claim 1, characterised in that said multi-carrier transmission system is a DMT transmission system.

3. A receiver, as claimed in claim 2, characterised in that said known sequence of symbols has a final symbol and said final symbol is transmitted in a DMT symbol immediately preceding an agreed symbol at which changes in transmission parameters will be effected, and said receiver is adapted to identify said final symbol and adjust said sample clock so that frame and sample clock synchronisation are maintained.

4. A receiver, as claimed in claim 3, characterised in that said transmission parameters include bit loading, energy loading and control channel frequency.

5. A receiver, as claimed in claim 3, characterised in that said receiver is adapted to adjust said sample clock without affecting regulation of the phase thereof.

6. A receiver, as claimed in either claim 1, characterised in that said multi-carrier transmission system is a DMT based VDSL system.

7. A receiver, as claimed in claim 1, characterised in that said known sequence of symbols has good autocorrelation properties.

8. A receiver, as claimed in claim 7, characterised in that said known sequence of symbols is a short pseudo random sequence.

9. A receiver, as claimed in claim 1, characterised in that said receiver is adapted to receive data relating to numbering intervals transmitted over said control channel.

10. A transceiver, including a transmitter and a receiver, characterised in that said receiver is a receiver as claimed in claim 1.

11. A multi-carrier transmission system using orthogonal carriers, in which a receiver sampling clock is phase locked to a pilot carrier, characterised in that said multi-carrier transmission system includes two transceivers as claimed in claim 10.

12. A transceiver, multi-carrier transmission system, or method, as claimed in claim 10, characterised in that said multi-carrier transmission system is a DMT system.

13. A transceiver, multi-carrier transmission system, or method, as claimed in claim 12, characterised in that said multi-carrier transmission system is a DMT based VDSL system.

14. In a multi-carrier transmission system using orthogonal carriers, in which a receiver sampling clock is synchronized with a transmitter sampling clock by extracting timing data from a pilot carrier on which a known sequence of symbols is transmitted, a method of compensating for changes in dynamic transmission parameters, characterised by using a selected carrier wave which continuously transmits a known sequence of symbols between the transmitter and the receiver and using said known sequence of symbols to regulate the receiver'"'"'s sampling clock phase, said known sequence having a predetermined pattern of symbols with autocorrelation properties which reproduce, unambiguously, timing information which can be extracted by correlation, the last symbol of said predetermined pattern being transmitted in a transmission system symbol before a symbol where agreed changes of dynamic transmission parameters are to be implemented.

15. A multi-carrier transmission system using orthogonal carriers and including at least two transceivers, in which a receiver sampling clock is synchronized with a transmitter sampling clock by extracting timing data from a pilot carrier on which a known sequence of symbols is transmitted, characterised in that there is provided a control channel over which data relating to changes in dynamic transmission parameters can be transmitted, and in that a receiver is adapted to extract timing data from said pilot carrier by autocorrelation, said timing data uniquely identifying a symbol at which a change in said dynamic transmission parameters will be effected.

16. A multi-carrier transmission system, as claimed in claim 15, characterised in that said multi-carrier transmission system is a DMT transmission system.

17. A multi-carrier transmission system, as claimed in claim 16, characterised in that said known sequence of symbols has a final symbol and said final symbol is transmitted in a DMT symbol immediately preceding an agreed symbol at which changes in transmission parameters will be effected, and in that a receiver is adapted to identify said final symbol and adjust its sample clock so that frame and sample clock synchronisation are maintained.

18. A multi-carrier transmission system, as claimed in claim 17, characterised in that said transmission parameters include bit loading, energy loading and control channel frequency.

19. A multi-carrier transmission system, as claimed in claim 15, characterised in that said multi-carrier transmission system is a DMT based VDSL system.

20. A multi-carrier transmission system, as claimed in claim 15, characterised in that said known sequence of symbols has good autocorrelation properties.

21. A multi-carrier transmission system, as claimed in claim 20, characterised in that said known sequence of symbols is a short pseudo random sequence.

22. In multi-carrier transmission system using orthogonal carriers and including at least two transceivers, a method of synchronising a receiver sampling clock with a transmitter sampling clock by extracting timing data from a pilot carrier on which a known sequence of symbols is transmitted, characterised by providing a control channel over which data relating to changes in dynamic transmission parameters are transmitted, and by a receiver extracting timing data, from said pilot carrier by autocorrelation, which uniquely identifies a symbol at which a change in said dynamic transmission parameters will be effected.

23. A method, as claimed in claim 22, characterised in that said multi-carrier transmission system is a DMT transmission system.

24. A method, as claimed in claim 23, characterised by said known sequence of symbols having a final symbol and transmitting said final symbol in a DMT symbol immediately preceding an agreed symbol at which changes in transmission parameters will be effected and, at a receiver, identifying said final symbol and adjusting said receiver'"'"'s sample clock so that frame and sample clock synchronisation are maintained.

25. A method, as claimed in claim 24, characterised in that said transmission parameters include bit loading, energy loading and control channel frequency.

26. A method, as claimed in claim 22, characterised in that said multi-carrier transmission system is a DMT based VDSL system.

27. A method, as claimed in claim 22, characterised by said known sequence of symbols having good autocorrelation properties.

28. A method, as claimed in claim 27, characterised by said known sequence of symbols being a short pseudo random sequence.