omnet-tdma

OMNeT++ TDMA is a simple and abstract implementation of a TDMA MAC protocol. It divides time into time slots which are then grouped into frames. For every frame a schedule is created which dictates nodes when to send. In this model, only the transmission of data is modelled. Control information is assumed to be exchanged out of band yielding a strongly idealized model.

To realize communication, a network interface card (TdmaInterface) is implemented to be used in any hosts, as well as a single oracle scheduler module (TdmaScheduler). Its operation is depicted below:

First, all TdmaMac layers, which are included in the TdmaInterface, register themselves to the TdmaScheduler. With that, the scheduler is able to create and distribute a new schedule when ever a frame begins. To be included into a schedule, nodes report their transmission buffer status to the scheduler. As depicted above, communication of control information is modelled in an idealized way where it always succeeds and has zero delay.

Getting Started

To use omnet-tdma, you need to have OMNeT++ 5.6.x installed.

• Clone this repo by git clone --recursive git@github.com:ComNetsHH/omnet-tdma.git. This will automatically also download INET v4.2.5 which is the latest supported version for omnet-tdma
• Create a new OMNeT++ workspace in the omnet-tdma directory.
• Import inet as existing project into the OMNeT++ IDE.
• Import tdma as existing project into the OMNeT++ IDE.
• Make sure inet is set as a reference project of tdma.
• Navigate to tdma/simulations/omnetpp.ini in the OMNeT++ IDE and click run. This will trigger the build of inet as well as tdma and start an example simulation.

If you have questions or encounter any issues, reach out to k.fuger@tuhh.de

Technical Specification

A detailed Doxygen documentation is available at https://tdma.omnetlense.com/

Usage

There are 4 parameters to tune the behavior of the protocol:

• slotDuration: The duration of a timesplot in ms (Used in TdmaMac and TdmaScheduler)
• frameLength: The number of timesplots per frame (Used in TdmaMac and TdmaScheduler)
• numRetries: How often a transmission is retried before abandoning the packet (Used in TdmaMac)
• monitorSchedule: A switch to record the entire schedule during simulation (Used in TdmaScheduler)

When the simulation ends, the scheduler collects a utilization statistic denoting how many of the time slots were used. It also prints the schedule periodically during simulation, which looks like this:

TdmaScheduler: End scheduling:
    Slot    |   nodeId
------------+--------------
       0    |   1
       1    |   2
       2    |   3
       3    |   4
       4    |   5
       5    |   6
       6    |   7
       7    |   8
       8    |   9
       9    |   1