Sequence Estimation Techniques for Digital Subscriber Loop Transmission with Crosstalk Interference

The use of reduced-state sequence estimation techniques in a digital subscriber loop receiver offers a potential performance improvement over conventional equalization techniques such as decision feed- back equalization (DFE). We show that the improvement can be especially significant in the presence of cyclostationary crosstalk because of the freedom that sequence estimation receivers afford in the choice of receiver sampling phase. We evaluate this advantage for Viterbi algorithm receivers. By simulation of two practical reduced-state sequence estimation receivers, we also demonstrate that in the presence of cyclostationary crosstalk, a substantial increase in maximum loop range (or equivalently, maximum bit rate) may be achievable compared to conventional DFE equalization