Measuring Propagation Time¶

Goals¶

In this example we explore the channel propagation time statistics for wired and wireless transmission mediums.

INET version: 4.4

Source files location: inet/showcases/measurement/propagationtime

The Model¶

The packet propagation time is measured from the moment the beginning of a physical signal encoding the packet leaves the transmitter network interface up to the moment the beginning of the same physical signal arrives at the receiver network interface. This time usually equals with the same difference measured for the end of the physical signal. The exception would be when the receiver is moving relative to the transmitter with a relatively high speed compared to the propagation speed of the physical signal, but it is rarely the case in communication network simulation.

Here is the network:

Here is the configuration:

[General]
network = PropagationTimeMeasurementShowcase
description = "Measure packet propagation time on the channel"
sim-time-limit = 1s

# source application ~96Mbps throughput
*.source.numApps = 1
*.source.app[0].typename = "UdpSourceApp"
*.source.app[0].source.packetLength = 1200B
*.source.app[0].source.productionInterval = exponential(100us)
*.source.app[0].io.destAddress = "destination"
*.source.app[0].io.destPort = 1000

# destination application
*.destination.numApps = 1
*.destination.app[0].typename = "UdpSinkApp"
*.destination.app[0].io.localPort = 1000

# enable modular Ethernet model
*.*.ethernet.typename = "EthernetLayer"
*.*.eth[*].typename = "LayeredEthernetInterface"

# data rate of all network interfaces
*.*.eth[*].bitrate = 100Mbps

Results¶

Here are the results:

Sources: omnetpp.ini, PropagationTimeMeasurementShowcase.ned

Try It Yourself¶

If you already have INET and OMNeT++ installed, start the IDE by typing omnetpp, import the INET project into the IDE, then navigate to the inet/showcases/measurement/propagationtime folder in the Project Explorer. There, you can view and edit the showcase files, run simulations, and analyze results.

Otherwise, there is an easy way to install INET and OMNeT++ using opp_env, and run the simulation interactively. Ensure that opp_env is installed on your system, then execute:

$ opp_env run inet-4.4 --init -w inet-workspace --install --chdir \
   -c 'cd inet-4.4.*/showcases/measurement/propagationtime && inet'

This command creates an inet-workspace directory, installs the appropriate versions of INET and OMNeT++ within it, and launches the inet command in the showcase directory for interactive simulation.

Alternatively, for a more hands-on experience, you can first set up the workspace and then open an interactive shell:

$ opp_env install --init -w inet-workspace inet-4.4
$ cd inet-workspace
$ opp_env shell

Inside the shell, start the IDE by typing omnetpp, import the INET project, then start exploring.

Discussion¶

Use this page in the GitHub issue tracker for commenting on this showcase.