Patent ID: 7471685

Claim:
A method for locating causes of a reduced quality of service of a data transmission system, comprising the steps of: monitoring the quality of service by repeatedly measuring a particular number of system parameters, determining a reduced quality of service by determining whether a value of at least one system parameter or a combination of values of a plurality of system parameters is located outside an allowed range; the method further comprising: monitoring the quality of service with a control element which is in the form of a physical or logical unit and which is connected to a user device or, at another location, to the data transmission system or which is integrated in the user device or in one of the already-existing network elements; automatically carrying out additional tests with the control element at the instant at which the control element determines a reduced quality of service in order to determine additional information concerning a system state of the data transmission system; and locating the causes of the reduced Quality of service with the control element on the basis of the measured values of the system parameters and the additional information.