Carrier re-activation in case of signal to nois ratio improvement

• US 20050124333A1
• Filed: 11/04/2004
• Published: 06/09/2005
• Est. Priority Date: 12/03/2003
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Van Elsen, Jeroen Celina Karel, Van Den Bogaert, Etienne Andre Hubert
• Granted Patent: US 7,933,318 B2
• Time in Patent Office: Days
• US Class Current: 455/420
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels

Abstract

The present invention relates to a first transceiver unit, acting as a receiver unit, and to a second transceiver unit, acting as a transmitter unit. The first transceiver unit measures the signal to noise ratio for each tone, and determine whether a tone shall be shut off, thereby reducing interference on neighboring lines and power consumption. If so, the first transceiver unit keeps on measuring the noise level over that tone. If the ratio of the initially measured signal level to the newly measured noise level exceeds a pre-determined threshold, then the first transceiver unit requests the second transceiver unit to re-activate that tone. A new initialization sequence is transmitted over that tone for initializing the frequency domain equalizer, for measuring the signal to noise ratio, and finally for agreeing on a bit loading.

Claims

1. A transceiver unit (TU1) comprising:

a receiver (RX2) adapted to receive from a physical channel (L) a signal modulated over at least one carrier,

a channel analysis means (ANAL) coupled to said receiver, and adapted, while an initialization sequence is being transmitted over said at least one carrier, to determine a signal component and a noise component within a frequency interval enclosing one carrier (k) out of said at least one carrier,

a communication means (COM1) adapted to establish a communication link with a peer transceiver unit (TU2),

a power remote control unit (PRCU) coupled to said channel analysis means and to said communication means, and adapted to request said peer transceiver unit to shut off said carrier (shut-off-req) if the ratio of said signal component to said noise component is lower than a first pre-determined threshold,

characterized in that said channel analysis means is further adapted, after said carrier has been shut off, to determine a pure-noise component within said frequency interval,

and in that said power remote control unit is further adapted to request said peer transceiver unit to re-activate said carrier (re-activate-req) if the ratio of said signal component to said pure-noise component is higher than a second pre-determined threshold.

2. A transceiver unit according to claim 1, characterized in that said channel analyzer is further adapted, while said initialization sequence is being transmitted over said at least one carrier, to determine:

an average signal power within said frequency interval, thereby determining said signal component,

an average noise power within said frequency interval, thereby determining said noise component,

and in that said channel analyzer is further adapted, after said carrier has been shut off, to determine an average pure-noise power within said frequency interval, thereby determining said pure-noise component.

3. A transceiver unit according to claim 1, characterized in that said transceiver unit is a digital subscriber line (DSL) transceiver unit.

4. A transceiver unit (TU2) comprising:

a transmitter (TX2) adapted to transmit over a physical channel (L) a signal modulated over at least one carrier,

a communication means (COM2) adapted to establish a communication link with a peer transceiver unit (TU1),

a power control unit coupled to said transmitter and to said communication means, and adapted to shut off a carrier (k) out of said at least one carrier upon a first request (shut-off-ind) from said peer transceiver unit,

characterized in that said power control unit is further adapted to power up said carrier upon a second request (re-activate-ind) from said peer transceiver unit,

and in that said transmitter is further adapted thereupon to transmit an initialization sequence over said carrier.

5. A transceiver unit according to claim 4, characterized in that said transceiver unit is a digital subscriber line (DSL) transceiver unit.