Management of a DSL copper network using built-in loop qualification tools

This master’s degree thesis project has been performed at the department for Access Signal Processing (ASP) at Ericsson AB in Älvsjö. Among other things this department does research concerning DSL (Digital Subscriber Line) technology. DSL provides fast data transfer over ordinary telephone lines. The advantage of using telephone lines is that almost all premises in developed parts of the world already have a telephone line installed, thus the installation cost is minimized both timeand money wise. The disadvantage is that a telephone line is not meant for high-speed data transfer. The status of the old copper wires is often unknown and lines that work just fine for telephone services might be useless for DSL. Moreover, a line for which a DSL service works well in the beginning could after some time be affected by increased disturbance since telephone lines are relatively unprotected against disturbances. For a DSL service provider it is interesting to estimate the properties of each line. Before any DSL-services are offered to a certain subscriber it would be desirable to know approximately how fast data can be transferred in that subscriber’s line so that a correct offer can be given. When DSL-services are up and running, supervision of the lines could help to detect errors and avoid disruptions of the services. If something goes wrong with the line, measurements are vital to the troubleshooting procedure. Historically, whenever a measurement should be performed in a line a technician had to be physically present at the CO (Central Office) to connect measuring equipment. In new DSL-equipment there are possibilities of measurements integrated in the same equipment that handles the ordinary data traffic. The goal of this thesis project was to suggest concepts on how these measurement possibilities could be efficiently exploited. Concepts have been developed in this project that utilize the fact that with Ericsson’s DSL equipment there is a measuring instrument constantly connected to each DSL-line in the network. The point-of-view has been changed from the individual DSL-lines to groups of several lines. The concepts also include regular monitoring measurements. Instead of just measuring when something has gone wrong, measurements are to be performed periodically and the data collected in a database for further analysis. Suggestions are made on how data collected at different occasions and at different lines could be correlated to extract as much information as possible. A toolbox of programs that put the concepts into action has been developed and is described in this thesis. Open THESIS REPORT 6 (85) Author: Date Martin Nilsson 800116-6951 2005-03-10 Open THESIS REPORT 7 (85) Author: Date Martin Nilsson 800116-6951 2005-03-10