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# SAHNE: A Simulation Environment for Ad Hoc Networks

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 (Library of Efficient Datatypes and Algorithms)

Overview

SAHNE has been originally designed for the simulation of topology control algorithms for directional communication, but it can also simulate omnidirectional communication. The physical transmission over the wireless medium can be simulated using two different models: radio (RF) and infrared (IR). In the RF model the signals are propagated omnidirectionally according to the free space propagation model with a variable path loss exponent. 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. We use the infrared propagation model proposed by Kahn and Barry 1997. 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.

SAHNE contains functions to assess the quality of the network topology, based on the measures congestion,dilation and energy, which are defined by Meyer auf der Heide et al. (TOCS 2004). These measures are indicators for routing performance that do not rely on a specific routing algorithm. Consider a path system P (consisting of, e.g., hop-optimal paths or energy-optimal paths) using the network topology. Then we define the maximum number of paths using an edge as the load of the edge. If we add the load of all interfering edges, then we obtain the congestion of an edge. The overall congestion is the maximum congestion of all edges in the network. Energy is the power consumption used for maintaining the network (unit energy) and the power used for the transmission of packets along the paths of P (flow energy). The length of the longest path in P is called dilation, which is an indicator for the routing time. SAHNE calculates hop-optimal and energy-optimal paths systems offline based on the current topology, determines interfering edges based on the signal-to-interference ratio and one of the propagation models. Then statistics for congestion and also for dilation and energy are generated.

SAHNE supports mobile nodes and provides random mobility models like the random waypoint model. Furthermore, the motion of the mobile nodes can be defined in a scenario file, in which paths are defined by waypoints and speed values.