The FSAN xDSL simulation tool Examples

FSAN

The FSAN xDSL Simulation Tool Examples

Introduction

There are currently five examples of full simulations available, each in a separate directory.

First

A first experiment for VDSL using mostly predifined definitions and routines.

Simple

An example main with many special definitions (i.e., scenario and tfplan).

GUI_VDSL

The main graphical user interface (GUI) example for VDSL experiments.

PBO

Example of a PBO experiment for VDSL using Reference-Frequency (Constant) power back off (PBO).

MixedServices

Example of testing many VDSL PBO methods on mixed service scenarios.

If Matlab is started in one of these directories the main routine is run by default (from startup.m).

First Example

This is the first experiment just to show how a simple VDSL experiment can be performed using mostly predefined definitions and routines. All is run out of a single Matlab file: Main.m.

More to be written here...

A Simple Example

Another simple example exists with more changes to the experiment structure, like special definitions for the scenario and the tfplan used. The main routine is ExMain.m. It uses userDefinitionsExample1.m to include many of the possible user changes (just a dummy example).

More to be written here...

Example GUI_VDSL

This is the main graphical user interface (GUI) example for VDSL experiments. It is started by calling uiMain.m in the examples/GUI_VDSL directory.

Input parameters

The basic set of input parameters can best be described by looking at the GUI setup window

With a menu selection one can select a scenario among a set of FSAN predefined scenarios. The topology and traffic setup for this scenario is shown as a sub-figure below the setup section. In the second menu it is possible to select if a pre defined FSAN noise model should be used or if it should be calculated from the scenario itself. The third menu makes the selection of VDSL modem/duplex method. The PSD mask for this modem is shown in a sub-figure below the setup section.

Connected to the VDSL duplex is the power back off (PBO) method. Currently there are four methods defined: reference length (RefLen), reference FEXT (RefFEXT), reference Noise (RefNoise) and reference frequency (RefFreq). If no PBO is wanted a "None" is selected in the PBO method menu. Two PBO parameters can be set: a length (for RefLen or RefFEXT) or a frequency (for RefFreq). For the RefFreq method a maximum length can be given. Also connected with a duplex method is an efficiency loss figure where efficiency losses due to cyclic prefix/suffix, guard bands etc. can be stated.

For time division duplex methods a time division can be given for up respectively down stream (for frequency division methods this is given as 1 and 1).

There are three flags that can be set.

Fast calculation - determines if calculations should use an optimized frequency axis which is slightly (1-2%) less accurate but can be up to 20 times faster.
Forces HAM band - determines if HAM band suppression should be imposed on VDSL PSD masks.
Test modem - determines if we should evaluate bit rates also for the ADSL modems in the structure.

Among the global parameters one can enter new values for

Background noise (dBm/Hz)
Maximum SNR available (dB)
The NEXT, FEXT and third circuit cross talk (3cXT) levels at 1MHz.

With the button "GO" the experiment is evaluated and a result window will appear. With "Close all" all windows will be closed (including the setup window).

User definitions

To be able to use new tt scenarios and new tf plans in the grapical user interface the user should make such additions in the file userDefinitions.m which is evaluated before the uiSetup is run.

The following examples show what can be made in the user definitions file:

userDefinitionsExample1.m - Shows many of the possible user changes (just a dummy example)
userDefinitionsBTap.m - Shows how to define a bridge tap scenario.

Output

With the graphical user interface a result window (example) is presented after the main evaluation routine is called. This window contains the rate information as well as figures showing the LT respectively NT side signals and noise curves.

The middle section of the result window contains bit rate information for each of the modems under test. For the downstream and upstream rates the numbers within parentheses are the xtalk margins to the given bitrate.

In the menu at the top left corner of the plot it is possible to select plots from any of the simulated modems. With the PlotIt button the plot is redrawn in a seperate window, thus allowing for further manupulation, e.g., zooming. A logarithmic frequency axis is possible by selecting 'Log' in the menu near f axis type.

For the plots in the result window:

blue is the received signal
red is the total noise
black is the alien noise

A PBO Scenario

In examples/PBO there is an example file ExPBO.m showing an example of a PBO experiment for VDSL using reference-frequency (a.k.a. Constant) power back off (PBO). This experiment tries to reproduce some of the results (curves) in [FSAN VDSL working group, "Power backoff methods for VDSL", ETSI TM6 Luleå 983/17A0, Sweden 22-26 June 1998.]
The whole experiment is run from ExPBO.m and is a good example on how to set up the ex structures to correspond to a certain experiment.

A Mixed Service scenario

In examples/MixedServices there is another PBO test: MixedServices.m. However, this exemplifies how we can run many PBO tests on some VDSL mixed service scenarios.

The whole experiment is run from the MixedServices.m file and is a relatively complex example of how to set up complex PSD definitions (dynamic frequency plan and dynamic PSD mask containment), as well as dynamic tt structures.

More to be written here...

References

FSAN VDSL working group, "Power backoff methods for VDSL", ETSI TM6 Luleå 983/17A0, Sweden 22-26 June 1998.