Multi-carrier transmission systems
First Claim
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 phase locking said receiver sampling clock to a pilot carrier, said receiver comprising:
- a feedback loop configured to control an oscillator means, said feedback loop using a feedback signal representative of an argument estimate of said pilot carrier, wherein said feedback signal is derived from an approximation of an argument of a complex number representative of said pilot carrier, said approximation retaining a full resolution of said complex number, and wherein said feedback loop controls said oscillator means so that said pilot argument tends to zero.
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Accused Products
Abstract
A multi-carrier transmission system using DMT. It is known to recover a receiver sample and clock from a reserved carrier, a pilot carrier having a fixed phase. A sampling clock oscillator in a receiver is then phase locked to the pilot carrier. Multi-carrier receivers, such as DMT receivers, are normally equipped with an FFT processor. A complex number representing the pilot carrier is then available from the FFT processor output. If an FFT processor is not available, a one frequency DFT processor can be provided to produce a complex estimate of the pilot carrier. In a DMT system, frame synchronization is handled separately from sampling clock synchronization, although the two processes are intimately related and frame synchronization must be acquired before sampling clock synchronization.
135 Citations
30 Claims
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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 phase locking said receiver sampling clock to a pilot carrier, said receiver comprising:
a feedback loop configured to control an oscillator means, said feedback loop using a feedback signal representative of an argument estimate of said pilot carrier, wherein said feedback signal is derived from an approximation of an argument of a complex number representative of said pilot carrier, said approximation retaining a full resolution of said complex number, and wherein said feedback loop controls said oscillator means so that said pilot argument tends to zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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14. A receiver as claimed in claim 13, wherein K=2.
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15. A transceiver comprising:
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a transmitter; and
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 phase locking said receiver sampling clock to a pilot carrier, said receiver including a feedback loop configured to control an oscillator means, said feedback loop using a feedback signal representative of an argument estimate of said pilot carrier, wherein said feedback signal is derived from an approximation of an argument of a complex number representative of said pilot carrier, said approximation retaining a full resolution of said complex number, and wherein said feedback loop controls said oscillator means so that said pilot argument tends to zero. - View Dependent Claims (18, 19)
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16. A multi-carrier transmission system using orthogonal carriers, in which a receiver sampling clock is phase locked to a pilot carrier, wherein said multi-carrier transmission system comprises:
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two transceivers, wherein each one of said two transceivers includes a transmitter, and a receiver, including a feedback loop configured to control an oscillator means, said feedback loop using a feedback signal representative of an argument estimate of said pilot carrier, wherein said feedback signal is derived from an approximation of an argument of a complex number representative of said pilot carrier, said approximation retaining a full resolution of said complex number, and wherein said feedback loop controls said oscillator means so that said pilot argument tends to zero.
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17. A method for synchronizing a receiver clock with a transmitter clock, in which the transmitter transmits a pilot signal in a multi-carrier transmission system, said method comprising the steps of;
controlling a sampling clock in said receiver so that an argument of said pilot carrier converges to zero, and said pilot carrier argument is approximated by arithmetic operation on a complex number representative of said pilot signal.
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20. A method for synchronizing a receiver sampling clock to a transmitter sampling clock in a multi-carrier transmission system using orthogonal carriers, in which said receiver sampling clock is synchronized with said transmitter sampling clock by phase locking said receiver sampling clock to a pilot carrier transmitted by said transmitter, said method comprising the steps of:
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deriving a complex number representative of said pilot carrier;
deriving from said complex number an approximation of an argument of said pilot carrier;
using said approximation of said argument as a feedback signal to control said receiver sampling clock, so that said feedback signal tends to zero. - View Dependent Claims (21, 23, 24, 25, 26, 27, 28, 29, 30)
using an approximation, A, to said pilot carrier estimation, wherein;
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30. A method as claimed in claim 29, wherein K=2.
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22. A method as claimed in 20, wherein said multi-carrier transmission system comprises a DMT based VDSL system.
Specification