A method of transmitting, using a discrete multi-tone technique, data between a first and a second transceiver over a plurality of metallic pairs connected between the first and second transceivers, providing a plurality of transmission channels, is disclosed.

A method of transmitting, using a discrete multi-tone technique, data between a first and a second transceiver over a plurality of metallic pairs connected between the first and second transceivers, providing a plurality of transmission channels, is disclosed.

A transmitter for transmitting data, using a discrete multi-tone modulation technique, to one or more receiver devices, each of which is connected to the transmitter device via at least one respective pair of wires, each receiver device being operable to receive signals detected as a change over time in the potential difference across the local ends of each respective pair of wires extending between the receiver and the transmitter device, is operable to transmit signals onto the wires extending between the transmitter device and the one or more receiver devices in a plurality of different modes, over a plurality of different channels, the different modes including phantom and differential modes and the different channels including a first set of phantom channels. The transmitter is further operable to select a second set of phantom channels from the first set, the second set being a subset of the first set comprising some or all of the phantom channels of the first set such that at least some of the phantom channels

A transmitter for transmitting data, using a discrete multi-tone modulation technique, to one or more receiver devices, each of which is connected to the transmitter device via at least one respective pair of wires, each receiver device being operable to receive signals detected as a change over time in the potential difference across the local ends of each respective pair of wires extending between the receiver and the transmitter device, is operable to transmit signals onto the wires extending between the transmitter device and the one or more receiver devices in a plurality of different modes, over a plurality of different channels, the different modes including phantom and differential modes and the different channels including a first set of phantom channels. The transmitter is further operable to select a second set of phantom channels from the first set, the second set being a subset of the first set comprising some or all of the phantom channels of the first set such that at least some of the phantom channels

A method and apparatus for transmitting data from a transmitter device to one or more receiver devices, each of the one or more receiver devices being connected to the transmitter device via a respective wire connection, the transmitter device being operable to transmit signals onto the wire connections over one or more different channels, the method comprising, for each of the one or more different channels: determining a value of a function S.sup..sup.m.sub.j,j, dependent on an upper bound for a channel capacity of the one or more channels and a channel gain of the jth channel; determining a transmission power S.sup.m.sub.j,j, for transmitting data along that channel based on S.sup..sup.m.sub.j,j; and transmitting, by the transmitter device, data over that channel to one or more of the receiver devices, the data being transmitted at the transmission power S.sup.m.sub.j,j determined for that channel.

A method and apparatus for transmitting data from a transmitter device to one or more receiver devices, each of the one or more receiver devices being connected to the transmitter device via a respective wire connection, the transmitter device being operable to transmit signals onto the wire connections over one or more different channels, the method comprising, for each of the one or more different channels: determining a value of a function S.sup..sup.m.sub.j,j, dependent on an upper bound for a channel capacity of the one or more channels and a channel gain of the jth channel; determining a transmission power S.sup.m.sub.j,j, for transmitting data along that channel based on S.sup..sup.m.sub.j,j; and transmitting, by the transmitter device, data over that channel to one or more of the receiver devices, the data being transmitted at the transmission power S.sup.m.sub.j,j determined for that channel.

A method and apparatus for transmitting data from a transmitter device to one or more receiver devices connected to the transmitter device via a respective wire connection, the transmitter device being operable to transmit signals onto the wire connections and a further wire connection at different tones, the method comprising: for each tone, allocating signals transmitted on the further wire connection as supporting signals for a particular wire connection, and measuring electromagnetic coupling between the further wire connection and that particular wire connection; using the measurements, determining a power allocation for transmitting a supporting signal on the further wire connection; for one or more of the tones: transmitting a signal onto the particular wire connection, and transmitting a supporting signal onto the further wire connection at the determined transmission power, thereby to cause crosstalk interference in the particular wire connection.

A method and apparatus for transmitting data from a transmitter device to one or more receiver devices connected to the transmitter device via a respective wire connection, the transmitter device being operable to transmit signals onto the wire connections and a further wire connection at different tones, the method comprising: for each tone, allocating signals transmitted on the further wire connection as supporting signals for a particular wire connection, and measuring electromagnetic coupling between the further wire connection and that particular wire connection; using the measurements, determining a power allocation for transmitting a supporting signal on the further wire connection; for one or more of the tones: transmitting a signal onto the particular wire connection, and transmitting a supporting signal onto the further wire connection at the determined transmission power, thereby to cause crosstalk interference in the particular wire connection.

Techniques are provided for fallback authorization routing. A merchant processor may receive authorization requests from one or more merchant systems. These authorization requests may be to authorize a transaction. The merchant processor may transmit these authorization requests over a first communication channel to an acquirer processor, which may then forward the requests to a payment network. If the merchant processor determines that the acquirer processor is not receiving the authorization requests, or is otherwise unavailable, the merchant processor may, as a fallback, transmit the authorization requests directly to the payment network through a second communication channel, thereby bypassing the acquirer processor. When the merchant processor receives some indication that the acquirer processor is available to process authorization requests, new authorization requests can be transmitted to the acquirer processor via the first communication channel.

A method of transmitting, using a discrete multi-tone technique, data between a first and a second transceiver over a plurality of metallic pairs connected between the first and second transceivers, providing a plurality of transmission channels, is disclosed.