Channel gain change detection and channel profile selection in a multicarrier system

This paper investigates the detection and identification of abrupt channel gain changes in multicarrier systems, which can be particularly noticeable in the area known as splitterless digital subscriber lines. Gross channel changes nominally lead to a need for retraining of the modems in the connection, but this paper introduces some mechanisms known as profile detection that can avert the need for retraining in a number of realistic situations. Specific methods are introduced that allow for the detection of an abrupt gain change and further minimize the probability of error in selecting from one of a set of profiles that have been previously observed (or conjectured) to characterize the possible modes of operation of the channel. Expressions for analysis are also provided.