Article

Reduced-delay protection of DSL systems against nonstationary disturbances

Marvell Semicond. Inc., Sunnyvale, CA, USA
IEEE Transactions on Communications (Impact Factor: 1.98). 12/2004; DOI: 10.1109/TCOMM.2004.836589
Source: IEEE Xplore

ABSTRACT In addition to being designed to successfully cope with stationary noise, crosstalk, and intersymbol interference, digital subscriber loop (DSL) systems need to be shielded from nonstationary disturbances, such as impulse noise and RF interference. Currently, deployed DSL systems achieve protection against nonstationary interference using a combination of Reed-Solomon (RS) codes and interleaving. However, interleaving results in delay. Long delays are undesirable in high-rate systems that support interactive applications. In this study, it is shown that the interleaving delay of DSL systems can be significantly reduced by performing erasure decoding of the RS codewords at the receiver. Three different techniques for determining the erasures are proposed. Use of the techniques results in a reduction of the interleaving delay that is required to mitigate worst-case impulse noise by up to a factor of 2, which is verified by simulation. Moreover, the techniques do not require any changes at the transmitter and therefore guarantee compatibility with currently deployed systems.

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    • "While this noise model is useful in providing an insight into the underlying behavior of communication systems, it ignores some other impairments which are prevalent in various communication environments. For instance , in addition to the additive Gaussian noise, impulsive noise is also of concern in many modern communication systems , such as widely deployed digital subscriber line (DSL) networks [2], power-line communications (PLC) [3], and underwater acoustics channels [4], [5]. Such impulsive noise is produced due to the presence of undesirable interference signals in the form of random bursts for a short period of time with a stronger power relative to the receiver thermal noise power. "
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    • "(C3) if and only if . Margin by its nature is a safety margin [16] and simultaneously a performance enhancer (in terms of error rate) [12]. Thus, going by the philosophy of distributed DSM whereby our concern is each user's well-being and not some single overall system metric, it is natural to model the problem as a min–max problem. "
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