In this example the network consists of one (real) UE connected to a (real) server.
The emulated 5G network includes a variable number of background cells. The latter produces interference
that affects the latency of packets exchanged between the (real) endpoints of the communication.

 
Communication between the simulator and the host OS is realized using namespaces linked
together via virtual ethernet (veth) interfaces. 
In particular, we configure the following scenario:

+++++++++++++++++++++++++     +++++++++++++++++++++++++     +++++++++++++++++++++++++
+     Namespace ns1     +     +         Simu5G        +     +     Namespace ns2     +
+                       +     +                       +     +                       +
+  Client App     [veth1]<--->[sim-veth1]   [sim-veth2]<--->[veth2]     Server App  +
+            192.168.2.2+     +                       +     +192.168.3.2            +
+                       +     +                       +     +                       +
+++++++++++++++++++++++++     +++++++++++++++++++++++++     +++++++++++++++++++++++++

The client (at the UE side) pings the server (@192.168.3.2) to measure the RTT of the communication. 
Such RTT increases with the interference, hence with the number of background cells in the 
emulated network.
IP addresses and routing tables are set up by using mrt files (see "routing_files" folder).

 
=== HOW TO BUILD AND RUN ===

1) Make sure that the emulation feature is enabled in the INET project:

- via the IDE: right-click on the 'inet' folder in the Project Explorer -> Properties;
               select OMNeT++ -> Project Features; 
               tick the box "Network emulation support".
- via the command line: in the root INET folder, type 'opp_featuretool enable NetworkEmulationSupport'.

  If the feature was disabled, recompile INET with the command 'make' (in the root INET folder).  


2) In order to be able to send/receive packets through sockets, set the application permissions: 

    sudo setcap cap_net_raw,cap_net_admin=eip path/to/opp_run
    sudo setcap cap_net_raw,cap_net_admin=eip path/to/opp_run_dbg
    sudo setcap cap_net_raw,cap_net_admin=eip path/to/opp_run_release


3) Compile Simu5G from the command line by running (in the root Simu5G folder):
    $ . setenv
	$ make makefiles
	$ make 
	
	
4) Setup the environment by typing:

    ./setup.sh	 
	 	
 	
5) Run the simulation by typing:

   ./run.sh -r <RUN_NUMBER>
    
   where RUN_NUMBER=0 --> 3 background cells
         RUN_NUMBER=1 --> 6 background cells
         RUN_NUMBER=2 --> 9 background cells
 
   
6) Run the sender application, e.g. by typing the command:
 
    (in a new terminal window) sudo ip netns exec ns1 ping 192.168.3.2
          
        
7) Clean the environment by typing:

    ./teardown.sh
   
============================