Marcello Valentini

We investigate the effect of non idealities in the diagonalizing precoder vectoring technique used for cancellation of the far-end crosstalk in downstream VDSL networks. By using analytical formulas, we estimate the average bit rate achievable as a function of both relative and absolute estimation errors. Several numerical examples are provided, in different scenarios and operation conditions. Results are presented covering an important aspect for practical applications: the transmitted power… Show more

We investigate the effect of non idealities in the diagonalizing precoder vectoring technique used for cancellation of the far-end crosstalk in downstream VDSL networks. By using analytical formulas, we estimate the average bit rate achievable as a function of both relative and absolute estimation errors. Several numerical examples are provided, in different scenarios and operation conditions. Results are presented covering an important aspect for practical applications: the transmitted power required to achieve a target bit rate, as a function of the line length. Finally, we provide some results on the impact of a smart quantization law, which limits the performance loss. Show less

This paper considers a VDSL downstream system where crosstalk is compensated by linear precoding. Starting from a recently introduced mathematical model for FEXT channels, simple analytical methods are derived for evaluating the average bit rates achievable, taking into account three of the most important nonidealities. First, absolute and relative estimation errors in the crosstalk coefficients are discussed, and explicit formulas are obtained to express their impact. A simple approach is… Show more

This paper considers a VDSL downstream system where crosstalk is compensated by linear precoding. Starting from a recently introduced mathematical model for FEXT channels, simple analytical methods are derived for evaluating the average bit rates achievable, taking into account three of the most important nonidealities. First, absolute and relative estimation errors in the crosstalk coefficients are discussed, and explicit formulas are obtained to express their impact. A simple approach is presented for computing the maximum line length where linear precoding overcomes the noncoordinate system. Then, the effect of out-of-domain crosstalk is analyzed. Finally, quantization errors in precoding coefficients are considered. We show that by the assumption of a midtread quantization law with different thresholds, a relatively small number of quantization bits is sufficient, thus reducing the implementation complexity. The presented formulas allow to quantify the impact of practical impairments and give a useful tool to design engineers and service providers to have a first estimation of the performance achievable in a specified scenario. Show less

We investigate the effect of non idealities in the diagonalizing precoder vectoring technique used for cancellation of the far-end crosstalk in downstream VDSL networks. The contribution of the paper is twofold: on one hand we provide analytical formulas to estimate the average bit rates achievable as a function of both relative and absolute estimation errors, on the other hand we show that, by adopting a smart quantization law, the number of quantization bits required for not exceeding a given… Show more

We investigate the effect of non idealities in the diagonalizing precoder vectoring technique used for cancellation of the far-end crosstalk in downstream VDSL networks. The contribution of the paper is twofold: on one hand we provide analytical formulas to estimate the average bit rates achievable as a function of both relative and absolute estimation errors, on the other hand we show that, by adopting a smart quantization law, the number of quantization bits required for not exceeding a given transmission rate loss can be smaller than that foreseen by previous analyses. Show less

Wireline communication using the copper plant is one of the major access techniques. The shorter the wires, the larger is the frequency band that can be exploited in an economically feasible way. Several technologies using frequency bands up to 30 MHz have been standardized during the last decade. Properties of the wireline channel for frequencies above 30 MHz are to a large extent unexplored. This paper investigates the limits of "ultra-wideband" communication over very short copper cables in… Show more

Wireline communication using the copper plant is one of the major access techniques. The shorter the wires, the larger is the frequency band that can be exploited in an economically feasible way. Several technologies using frequency bands up to 30 MHz have been standardized during the last decade. Properties of the wireline channel for frequencies above 30 MHz are to a large extent unexplored. This paper investigates the limits of "ultra-wideband" communication over very short copper cables in terms of exploitable bandwidth and data rate. Extrapolations of standard cable models, whose validity has been verified by means of measurements, are used for channel modeling. The CISPR 22 standard forms the basis for the analysis of ingress and egress. Show less