Step 14. Introducing antenna gain
=================================

Goals
-----

In the previous steps, we have assumed an isotropic antenna for the
radio, with a gain of 1 (0dB). Here we want to enhance the simulation by
taking antenna gain into account.

The model
---------

For simplicity, we configure the hosts to use :ned:`ConstantGainAntenna`.
:ned:`ConstantGainAntenna` is an abstraction: it models an antenna that has
a constant gain in the directions relevant for the simulation,
regardless of how such an antenna could be implemented in real life. For
example, if all nodes of a simulated wireless network are on the same
plane, :ned:`ConstantGainAntenna` could correspond to an omnidirectional
antenna such as a vertical dipole. (INET contains support for
directional antennas as well.)



.. literalinclude:: ../omnetpp.ini
   :language: ini
   :start-at: [Config Wireless14]
   :end-before: #---

Results
-------

With the added antenna gain, the transmissions are powerful enough to
require only two hops to get to host B every time, as opposed to the
previous step, where it sometimes required three. Therefore, at the
beginning of the simulation, host R1 can reach host B directly. Also,
host R1 goes out of host A's communication range only at the very end of
the simulation. When this happens, host A's transmission is routed
through host R2, which is again just two hops.



.. video:: media/wireless-step14-1.mp4
   :width: 655
   :height: 575



   <!--internal video recording, playback speed animation speed 1-->

**Number of packets received by host B: 1045**

Sources: :download:`omnetpp.ini <../omnetpp.ini>`,
:download:`WirelessC.ned <../WirelessC.ned>`

Discussion
----------

Use `this
page <https://github.com/inet-framework/inet-tutorials/issues/1>`__ in
the GitHub issue tracker for commenting on this tutorial.