Method and apparatus for line rate control in a digital communications system

摘要

A method and communications device for controlling the line rate used on a communications link. The method includes receiving frames of digital information, computing a measure of the number of frames received in error in a sliding time window and generating a command to change the line rate as a function of the measure. The use of a sliding time window captures variations in the line quality over an extended period of time; thus, significant disturbances which might otherwise be missed are captured. The measure of the number of frames received in error is computed by applying a many-to-one mapping to the actual number of frame errors received since a previous sampling instant; thus, insignificant short-term disturbances which might otherwise temporarily corrupt the line quality estimate are eliminated. As a result, commands to change the line rate are based on a better estimate of line quality and the incidence of thrashing in the presence of recurring noise bursts is reduced, leading to increased data throughput. A back-off timer may be used for preventing an upgrade in line quality from occurring immediately following a downgrade, further decreasing the incidence of thrashing. <IMAGE>