transmission between any pair of test nodes whose GPS positions are provided by files. The result of the computed path loss of each pair of test nodes for every topology in a given scenario is saved in a binary format file (i.e., path-loss-matrix file). This file will serve as an input into the Range Model module to determine the link connection between any pair of communicating test nodes

in a topology.

Since the latest version of TIREM is available for interfacing with a C++ program in a Microsoft Windows XP environment, a C++ program named was developed and executed in the Windows XP environment to create a binary file (path-loss) to store the computed path loss of every symmetric pair of nodes. The program reads in the information of files (each test node has an associated file). It then reads in the GPS information of all the test nodes at every topology from the

files and calls functions in the TIREM library

compute nodes.

the path loss in In this current

dB (decibel) for version, a pair

every pair of nodes

to of is

considered symmetric in radio losses in either direction (send reciprocity theorem [4], this

communication (equal path or receive)). Based on the assumption is reasonably

acceptable even with earth terrain and consideration of the effect of the earth ionsphere using symmetric communication, the size of the

with no layer. By path-loss-

matrix file is reduced in half. The following description of the path-loss-matrix file:

is

a

structure

•

The network topology number in binary integer format (typically 4 bytes)

•

Path losses in binary floating point (single precision) format (typically 4 bytes in IEEE 754 format [5] (IEEE Standard for Binary-Floating Arithmetic) for most system implementation) of strictly upper triangular matrix (not including diagonal) elements (symmetric communication).

•

The data structure is repeated until the last topology of the scenario.

•

binary

in

List of node identification numbers integer format (typically 4 bytes).

(IDs)

Using a typical 4-byte size for integer and floating point representation, the path-loss-matrix file size can be

determined by:

^{ }

1 +_{ }+

2

2 −

4

where

is the number of test nodes, and

is the number

of topologies in a scenario.

The computed path loss results are listed sequentially, based on the rows of the strictly upper triangular matrix, where the elements are specified by the node IDs listed at the beginning of the path-loss-matrix file. Using a list of node IDs to specify the strictly upper triangular matrix enables the MANE server to read in and locate the pre- computed path losses.

# The output of the

program is the computed path-loss-

matrix file which is used as an input for the modified MANE program which accepts a new option specified by

or

and the path-loss-matrix file

name. With the binary format representation in the path- loss-matrix file, the Range Model module can quickly read in pre-computed path losses and speedily determine the link connectivity of node pairs by using the overloading

function feature of C++ programming.

The current path-loss computation process is illustrated in Figure 1. The numbered arrows show the flow of data in the process. The first step is to use the ARL Topodef tool

to design a specific dynamic topology of a MANET under

test and to generate a set of

files, the arrow labeled (1).

The second step is to use the

program to read in the

contents of the

files (2) and use the TIREM library (3)

to compute and generate the path loss matrices (4).

The

last step is to transfer the path-loss-matrix file (and the files) to the MANE test bed.

Figure 1. Pre-computation process and the MANE test bed

Executing the MANE software system with the

option

specifies that it should use the pre-computed path-loss matrix file. Conversely, without the specified option, the path-loss matrix is disregarded by the MANE system.

Whether the option

is specified, the MANE system