English to Italian Law/Patents Telecom(munications) digital communication

....digital communication systems where the transmission medium typically is copper wiring. Most commonly, the copper wiring consists of twisted pairs (also referred to as "lines" or "loops")

Such crosstalk can be the limiting factor in determi-ning the data rates and symmetries of offered DSL services at various loop reaches, so spectrum management finds some level of compromise between the various DSL service offerings that may be si-multaneously deployed.

Power control in DSL systems differs from power control in wireless systems because, although the DSL environment varies from loop to loop, it does not vary over time. Since fading and mobility are not issues, the assumption of perfect channel knowledge is reasonable. Since fading and mobility are not issues, the assumption of perfect channel knowledge is reasonable. This allows the implementation of sophi-sticated centralized power control schemes. On the other hand, unlike the wireless situation where flat fading can often be assumed, the DSL loops are seve-rely frequency selective.

Several upstream power back-off methods have been proposed in VDSL. All current power back-off methods attempt to reduce the interference emission caused by shorter loops by forcing the shorter loop to emulate the behavior of a longer loop. For example, in the constant power back-off method, a constant factor is applied across the frequency in upstream transmission bands, so that at a particular reference frequency the received PSD level from shorter loops is the same as the received PSD level from a longer reference loop.