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Digital Subscriber Lines

Digital Subscriber Lines

Fast Internet access for high-quality multimedia transmission calls for bit rates which exceed the capabilities of conventional voiceband modems (56 kbit/s) and ISDN lines (128 kbit/s) by an order of magnitude or more. Several new digital transmission technologies allow to meet that demand: fibre optics, coaxial cable, wireless (fixed or mobile), and digital subscriber lines (xDSL). Only the last one makes full usage of the existing infrastructure provided by conventional telephone networks.  Virtually every household or office is already connected to this network by a pair of twisted copper wires. For the Plain Old Telephony Service (POTS), only the low-frequency band up to 4 kHz has been used. High transmission

rates of several hundred kBit/s up to several MBit/s exploit a much wider frequency range (up to several MHz) which requires sophisticated signal processing, modulation, and coding algorithms to cope with the significant distortions and cable losses at high frequencies and with the significant level of cross-talk between copper wires sharing the same cable bundle.

Suggested Topics for Seminar Presentations

Fundamentals: Transmission Environment and Signal Processing

    Telephone subscriber loop environment
    Twisted-pair channel modeling
    Transceiver front-end noise models
    Channel capacity
    Hybrid circuits
    Analog front-end precision
    Channel equalization
    Echo cancellation
    Error correction and trellis coding

DSL Systems: System and Transceiver Architectures

    DSL (Digital Subscriber Lines)
    HDSL (High Bit Rate Digital Subscriber Lines)
    ADSL (Asymmetrical Digital Subscriber Lines)
    SDSL (Symmetric Digital Subscriber Lines)
    VDSL (Very High Bit Rate Digital Subscriber Lines)
    The FSAN/FTW simulator


The seminar is organized by the Signal Processing and Speech Communication Laboratory at the Institute for Communications and Wave Propagation of TU Graz. Students will work on a selected topic, create a self-study WWW document, and give an oral presentation in class during a 45 minute discussion session. Work in small groups of 2 or 3 students is strongly encouraged.Remote participation via telecooperation tools and IP video-conferencing will be supported. The working language will be English.

The first meeting will be held in the seminar room of the Institute of Communications and Wave Propagation, Inffeldgasse 12, first floor, on Thursday, Oct 11, 2001, at 16:00 hrs. This will be used to assign groups and topics, and to coordinate the seminar schedule.

Presentation Schedule

Nov 15 
H. Koeppl, Twisted-pair channel modeling 
Nov 22 
D. Schwingshackl, Channel equalization 
Nov 29 
T. Brandtner, Error correction and trellis coding, (presentation slides
Dec 13 
D. Shutin, Echo cancellation 
B. Badic, DSL (Digital Subscriber Lines) 
Jan 17 
F. Hammer, ADSL (Asymmetrical Digital Subscriber Lines) 
K. Doppler, VDSL (Very High Bit Rate Digital Subscriber Lines) 
Jan 24 
G. Matzenauer, The FSAN/FTW simulator 

References/Course Material

The suggested seminar topics follow the chapters in the book

  • Walter Y. Chen, DSL Simulation Techniques and Standards Development for Digital Subscriber Line Systems. Indianapolis: Macmillan Technical Publishing, 1998.

The FTW/FSAN xDSL simulation tool can be downloaded from the webpages of the Forschungszentrum Telekommunikation Wien under

Created by marian
Last modified 2007-06-18 12:18