In vectored DSL systems, a disorderly leaving event (DLE) occurs when one user suddenly unplugs or turns off the CPE. The impedance on the CPE side is suddenly changed and it thereby changes the crosstalk channel from the disorderly leaving line to the other vectored lines. The mismatch between the precoder and the changed crosstalk channel could make some of the other vectored lines to retrain. However, channel tracking based on the standard channel estimation method is too slow to solve the problem. In this paper, we propose a fast channel estimation method which needs only a few error samples. The simulation results show that channel tracking based on the proposed fast channel estimation method is an effective and robust way to avoid retrains on a DLE.
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