Knowledge Base

Title Authors Last Update Category
DSL Crosstalk Simulation and Calibration Tim Clark (UNH-IOL)

The performance of DSL transceivers can be impaired by interference from other transceivers operating over wires in the same binder group. It is therefore important to test DSL transceivers in the presence of crosstalk, which can be simulated in a programming environment such as MATLAB. The simulated crosstalk can then be exported to an arbitrary waveform generator (AWG) for injection onto the line through a high-impedance noise injection circuit. This document describes a method of crosstalk simulation and calibration whereby white gaussian noise (WGN) is passed through a frequency-domain filter that gives the noise the spectral characteristics of crosstalk. The crosstalk is calibrated by measuring its power with a vector signal analyzer (VSA) and adjusting the output level on the AWG to achieve the desired noise power. By using MATLAB to estimate the simulated crosstalk power in the same manner as the VSA, the calibration can be performed in MATLAB without taking actual measurements.

May 11, 2004 White Papers
ADSL Tutorial Matthew Langlois (UNH-IOL)

This tutorial provides an overview of ADSL technology and focuses on the physical layer as defined in ANSI T1.413-1998. From the introduction: "The demand for high-speed data networks in the "last mile" has driven the need for robust, interoperable, and easy to use multi-vendor Digital Subscriber Line (DSL) access solutions. DSL collectively refers to a group of technologies that utilize the unused bandwidth in the existing copper access network to deliver high-speed data services from the distribution center, or central office, to the end user. DSL technology is attractive because it requires little to no upgrading of the existing copper infrastructure that connects nearly all populated locations in the world. In addition, DSL is inherently secure due to its point-to-point nature."

June 26, 2012 Tutorials
ADSL Systems - An Overview Praveen Reguraman (UNH-IOL)

An overview of ADSL systems that includes network architecture, protocol architecture, typical ADSL implementations, RFC1483 bridging, PPP over ATM over ADSL, and PPP over Ethernet over ADSL.

June 26, 2012 Tutorials
A G.hs Handshaking Protocol Analyzer For ADSL Matthew Langlois

A protocol analyzer is a device that non-intrusively monitors bi-directional communications on a link, demodulates the physical layer signals, and captures the raw binary data for subsequent state and timing analysis. There are no commercial products currently available that perform this function for ADSL link initialization procedures. In this project, a MATLAB application was developed that enables capture (via a digital sampling oscilloscope) and protocol analysis of the first segment, known as handshaking, of the ADSL link initialization procedure. The protocols of interest are ITU-T G.994.1 (G.hs), which defines the activation and handshaking procedures used by complaint ADSL equipment, and ITU-T G.992.1 (G.dmt), which defines the physical layer requirements of ADSL equipment utilizing the Discrete Multi-Tone (DMT) line code.

December 14, 2001 Theses