DSL Crosstalk Coefficient Acquisition Using SNR Feedback

Rapid acquisition of accurate crosstalk estimates is a core requirement for effective downstream (access node to modem) precoding in Digital Subscriber Line (DSL) systems. Here we show that signal-to-noise ratio (SNR) reports can be used to perform this task by 'tuning' the precoder i.e., iterating alternate steps of estimation and precoder adaptation. Such an approach has the advantage that it can be applied to existing (legacy) DSL modems. Using techniques from stochastic control we show such estimation can be designed.