Military Communications and Information Technology: A Trusted ...

480 Military Communications and Information Technology...
economy, business, daily life etc. But generally it states that roughly 80% of the effects
come from 20% of the causes.
Table I. Time of generation in each to each method
Number of devices Time of data generation
100 1 h 22 min.
200 5, 5 h
500 34 h 40 min.
1000 5 days 8 h
2000 23 days
5000 145 days
Applying this rule to communication system we can assume, that from point
of view of single user, 80% realized connections are addressed to only 20% of other
users. For the simplification of further considerations let’s assume that each user
communicates with only 20% of other users. It lets us for applying “according to
needs” method.
VI. According to needs method
In this method, only the required relations are established. In this case,
the number of relations satisfies the condition:
½ * N ≤ R < ½ * N * (N – 1).
Examples of generation times for different numbers of devices and for the case,
which is consistent with our assumption (arising from the Pareto principle) are
given in the table 2 in column 2. For comparison, column 1 shows the generation
times using the each to each method. Column 3 presents generation times, assuming
that each user communicates with at most 100 other users. In practice, the relations
are defined manually, using a symmetric table whose rows and columns are
identified by numbers of devices. Table entries on the diagonal are unavailable,
because establishing relation with the device itself has no practical meaning. Placing
the symbol X in a cell at the intersection of row i and column j means establishing
a relation between devices i and j.
The efficiency of this method depends on the ability of perception of the operator.
To imagine the scale of difficulty one can compare this process to lay the puzzle,
where the number of elements corresponds to the number of devices. If the image
consists of 1000 items such task seems not feasible in a short time. Suppose that
a large screen monitor (e.g. 21’’) can fit a part of table with the dimension 40 x 40
devices. If 1000 devices in the system works, such a part is just one of 625 parts.
Advantages: Number of relations adapted to real needs. The relatively short generation
time. Adequate for the institution, where some connections are not allowed.