Abstract
As an important solution to “the last mile” access, digital subscriber loops (DSLs) are still maintained in a huge plant to support low-cost but high-quality broadband network access through telephone lines. The discrete multi-tone (DMT) transmissions constitute a baseband version of the ubiquitous orthogonal frequency division multiplexing. While the DMT is ideally suited to deal with the frequency selective channel in DSL, the presence of bursty impulsive noise tends to severely degrade the transmission performance. In this paper, we analyze the statistics of impulsive noise and its effects on the received signals, with the aid of a hidden semi-Markov process. The closed-form bit error rate expression is derived for the DMT system for $Q$ -ary quadrature amplitude modulation under practical noise conditions and for measured dispersive DSL channels. Instead of relying on the simplified stationary and impulsive noise process, our noise model considers both the temporal and spectral characteristics based on the measurement results. The simulation results confirm the accuracy of the formulas derived and quantify the impact both of the impulsive noise and of the dispersive channel in DSL.
Highlights
The popularity of the wired broadband network is pushing them towards their limits
We provide a computationally convenient expression for populating the look-up table (LUT) based on the memoryless nonlinear transform function proposed in [20]; 4) with the aid of a Hidden Semi-Markov process, we derive the closed-form bit error rate (BER) formula of discrete multi-tone (DMT)-based digital subscriber loops (DSLs) systems relying on Q-ary quadrature amplitude modulation (QAM) under a practical noise model and a dispersive channel; 5) we verify the accuracy of our BER formula by simulation results, where the dispersive channel is extended to 106 MHz, which is the bandwidth of the first version of G.fast
In this paper, we have improved the methods in [20] by providing computationally convenient expressions confirmed by our simulation results, which prove that the impulsive noise generated reflects the practical DSL spectral characteristics
Summary
The popularity of the wired broadband network is pushing them towards their limits. The fibre-to-the-home (FTTH) concept, which is expected to satisfy the escalating throughput demands, is still not a ubiquitous reality at the time of writing, since its installation is costly and in historic architectural regions it is outright banned. Our main contributions are as follows: 1) we commence by a brief survey of the development of copper-based data-communications from a physicallayer perspective; 2) we conceive both a stationary and an impulsive noise model, which is capable of accurately reflecting both the temporal and spectral characteristics of practical channels; 3) to accurately model the non-Gaussian coloured impulsive noise in DSL, a look-up table (LUT) is necessary for characterising the relationship between the autocorrelation function of Gaussian distributed variables and the target Weibull distributed variables. We provide a computationally convenient expression for populating the LUT based on the memoryless nonlinear transform function proposed in [20]; 4) with the aid of a Hidden Semi-Markov process, we derive the closed-form BER formula of DMT-based DSL systems relying on Q-ary QAM under a practical noise model and a dispersive channel; 5) we verify the accuracy of our BER formula by simulation results, where the dispersive channel is extended to 106 MHz, which is the bandwidth of the first version of G.fast.
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