SAHNE - A Simulation Environment for mobile Ad hoc Networks

Authors:: Klaus Volbert <kvolbert@upb.de> , Stefan Rührup <sr@upb.de>

SAHNE is a simulation environment which allows to simulate the wireless communication and interaction between the nodes of an ad hoc network. It provides a graphical user interface based on LEDA (http://www.mpi-sb.mpg.de/LEDA/leda.html).

The User Interface

The user interface allows you to switch between different views and toggle the display of transmissions, directed edges etc. on and off. Additional information to any node or any edge is available by mouse click:

+--------------+--------------+-----------------+----------------+
| click        | normal view  | reference graph | data structure |
|              | (network)    |                 | (sector graph) |
+--------------+--------------+-----------------+----------------+    
| left         | node info    | node info       | outgoing edges |
| left+Ctrl    | range        |   --            |   --           |
| left+Shift   | sectors      |   --            |   --           |
| middle       | sector info/ |   --            | redraw         |
|              | transmission |                 |                |
| right        | Kanteninfo   |                 | ingoing edges  |
| double click | zoom         | zoom            | zoom           |
| drag         | move         | move            | move           |
+--------------+--------------+-----------------+----------------+

Simulation Parameters

The simulation parameters are stored in a configuration file (default: "sahne.cfg").

SAHNE supports various mobility models and the use of predefined scenarios. A scenario file is an ASCII text file with the following entries:

nn = node number with minimum and maximum velocity
wp = waypoints: coordinates of waypoints
ac = activity: time step in which a node is activated/deactivated
br = break: time step in which a node stops/resumes moving

Example:

nodes=2              | first line: number of nodes
nn 0 0 0             | nn <node no> <min_speed> <max_speed> 
nn 1 10 20           |
wp 0 200 200         | wp <node no> <x1> <y2> ... <xn> <yn> 
wp 1 300 300 800 800 |
ac 1 50 1000 2000    | ac <Knotennr> <t1> ... <tn> 
br 1 10 5000         | br <Knotennr> <t1> ... <tn> 
end                  | last line: end of file token

Notes:

A movable node should have at least two waypoints
A velocity of -1 means that this value is taken from the configuration file
<t1> means a time step, <x1> <y2> a pair of coordinates
Comments are allowed and startet with #.
Only positive coordinates are allowed
Size of the bounding box: xmin = ymin := 0. xmax and ymax are taken from the entries.

Transmission Details

Every node in the network has a protocol stack that consists of four layers:

User Layer
Scheduling Layer
Routing Layer
Transmitter

The physical transmission over the wireless medium is simulated using two different models: radio (RF) and infrared (IR). In the RF model the signals are propagated omnidirectional according to the free space propagation model. In the IR model a node may have several transceivers which are aligned to different directions. Signals are propagated unidirectional according to the directional characteristics of the IR transmitter. In both models the nodes may transmit with different transmission powers. If packets are received the node measures the received power. Furthermore, interferences between signals which are transmitted at the same time are taken into account.