Fast Mitigation of Sudden Termination Changes in Wideband Wireline Systems

Vectoring enables cooperative crosstalk mitigation in wideband wireline systems. A sudden termination change within a vectored group alters the entire perceived channel matrix and thus disturbs the vectoring operation, since the precoder, which is tuned to the channel before the change, is no longer up to date. We analyze the resulting residual crosstalk and its impact on performance degradation during showtime for both linear and non-linear precoding systems. To cover, a new channel matrix must be estimated to update the precoder accordingly. We use a model-based approach to track a vector instead of estimating the full matrix. Based on this vector, simplified precoder updating methods for both the precoding systems are presented accounting for a sudden line deactivation or reactivation in a vectored group. As an alternative to the state-of-the-art methods, the proposed procedures significantly reduce the complexity of both channel estimation and precoder updating and minimize the disturbed period for active users.