Telefonaktiebolaget Lm Ericsson (Publ)

Infineon Technologies Ag

Torbj&ouml;rn Randahl

Stefan Barkar&ouml;

Albin Johansson

Allan Olson

Anders S&ouml;derb&auml;rg

Tore Andr&eacute;

To minimize power dissipation in a line driver ( ) in a central office (CO) for driving a DSL connection to a network terminal (NT) with a predetermined maximum constellation size, the central office (CO) supplies the line driver ( ) with a predetermined supply voltage during a training sequence, and transfers data with a predetermined power spectral density in all available channels. The network terminal (NT) measures the signal-to-noise ratio of each channel, and transfers information to the central office (CO) about channels having signal-to-noise ratios that enable transfer of data. The central office (CO) reduces the power spectral density to a lowest possible value that still enables transfer of data in all channels having signal-to-noise ratios above a predetermined threshold as set by the maximum constellation size, calculates a sum of power to be transmitted in said channels, converts said sum into a corresponding line driver output voltage, and reduces the line driver supply voltage in correspondence thereto.

Method and arrangement for minimizing power dissipation in a line driver

To secure an ADSL connection between a first ADSL transceiver ( ) in a central office and a second ADSL transceiver ( ) on a subscriber's premises on a telephone line ( ) between a SLIC ( ) in the central office and a telephone ( ), a request to the SLIC ( ) to apply a ringing signal to the telephone line ( ) is detected. In response to such detection, the first ADSL transceiver ( ) switches from a normal bit rate to a lower bit rate for the ADSL connection, and orders the second ADSL transceiver ( ) to do the same before the ringing signal is applied. In response to an off-hook condition, the lower bit rate is maintained for the ADSL connection. In response to an on-hook condition after the off-hook condition as well as in response to a disappearance of the ringing request without an off-hook condition, the first ADSL transceiver ( ) switches back to the normal bit rate and orders the second ADSL transceiver ( ) to do the same.

Method and an arrangement for securing an ADSL connection

At the output of a line driver ( ) connected to a long transmission line, signals received on the transmission line are only a fraction of signals transmitted by the line driver on the transmission line. To minimize the transmitted signal with its distortion and noise in the receive path of the line driver, an additional driver ( ) having the same voltages and currents in the signal path, is added. The additional driver ( ) drives an additional load (Z ). The signal transmitted to the transmission line together with its superimposed received signal, is subtracted from the signal from the additional driver ( ), which is not superimposed on any received signal. The resulting signal is reduced from transmitted signal, transmitted distortion and transmitted noise. To minimize die size and power consumption, the additional driver ( ) is scaled, but the distortion remains unchanged compared to the &ldquo;normal&rdquo; line driver.

Echo and distortion cancellation arrangement

To secure an ADSL connection to an ADSL transceiver connected to a telephone line to be used also by an associated telephone, the telephone is normally kept disconnected from the telephone line and a predetermined number of bits is allocated to the ADSL connection. Upon an off-hook condition of the telephone in connection with an outgoing call, and upon a presence of a ringing signal on the telephone line or an off-hook condition of the telephone in connection with an incoming call, a predetermined lower number of bits is allocated to the ADSL connection before the telephone is connected to the telephone line.

Growing community of inventors

Nacka, Sweden

Torbjörn Randahl

Growing community of inventors

Nacka, Sweden

Torbj&ouml;rn Randahl

Torbjörn Randahl