Communication systems engineering
Communication systems engineering
Synchronization with DMT modulation
IEEE Communications Magazine
Modeling and evaluation of the indoor power line transmission medium
IEEE Communications Magazine
Analog-to-digital converter survey and analysis
IEEE Journal on Selected Areas in Communications
Optimized interpolator filters for timing error correction in DMT systems for xDSL applications
IEEE Journal on Selected Areas in Communications
Analysis of the cyclic short-term variation of indoor power line channels
IEEE Journal on Selected Areas in Communications
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Discrete multitone (DMT) modulation is a suitable technique to cope with main impairments of broadband indoor power-line channels: spectral selectivity and cyclic time variations. Due to the high-density constellations employed to achieve the required bit-rates, synchronization issues became an important concern in these scenarios. This paper analyzes the performance of a conventional DMT timing recovery scheme designed for linear time-invariant (LTI) channels when employed over indoor power lines. The influence of the channel cyclic short-term variations and the sampling jitter on the system performance is assessed. Bit-rate degradation due to timing errors is evaluated in a set of measured channels. It is shown that this synchronization mechanism limits the system performance in many residential channels. Two improvements are proposed to avoid this end: a new phase error estimator that takes into account the short-term changes in the channel response, and the introduction of notch filters in the timing recovery loop. Simulations confirm that the new scheme eliminates the bit-rate loss in most situations.