II.1.5. Wireless networks
a) Definition
A wireless network (in French réseau sans fil) is a
network in which at least two terminals can communicate without telegraphic
connection. The wireless networks are based on a connection use, of the radio
waves (radio and infra-red) instead of usual cables. Wireless networks make
possible to connect easily the distant equipment of ten meter to a few
kilometers.
b) Various types of wireless networks
We distinguish several categories of wireless networks, according
to the zone of cover.
II.1.5.1. Wireless Personal networks
The wireless personal network (also called wireless individual
network or wireless domestic network; and noted WPAN:
Wireless Personal Area Network), concerns the wireless
networks of a short distance (approximately 10 meters). There are several
technologies used for the WPAN:
- Bluetooth: Principal technology used for
the WPAN is Bluetooth, proposing a theoretical output of 1Mbps
for a maximum range of about thirty meters. Bluetooth, known also under the
name IEEE 802.15.1.
- HRF (Home Radio operator Frequency):
launched by HRF Working Group (formed in particular by manufacturers Compaq,
HP, INTEL, Siemens, Motorola and Microsoft) proposes a theoretical output of 10
Mbps (a range from approximately 50 to 100 meters without amplifier. This
technology was replaced by Wi-Fi (wireless fidelity) with incorporation of a
microprocessor and a Wi-Fi adapter)
- ZigBee technology (known under the name
IEEE 802.15.4) makes possible to obtain connections without wire.
§ Wireless Local Area Networks (WLAN):
The Wireless Local Area Network is a network which makes possible to cover the
equivalent of a local area network, that is to say a range of approximately a
hundred meters.
§ Wireless underground railway networks
(WMAN): The Wireless underground railway network (Wireless
Metropolitan is based on the standard IEEE 802.16. The Radio Loop Local offers,
a productive flow from 1 to 10 Mbit/s for a range from 4 to 10 km, which
intends mainly this technology to the operators of telecommunication.
§ Wireless Wide Area Networks (WWAN):
The Wireless Network WWAN is also known under the name of mobile cellular
network. They are the most widespread wireless networks because all the mobile
telephones are connected to a wireless wide area network. Here are its
principal technologies:
o GSM (Total System for Mobile Communication)
o GPRS (General packet Radio operator Service)
o UMTS (Universal Mobile System Telecommunication System)
Conclusion
The second chapter of my work has deal with the generality of
computer network; this chapter is very important because its theories helped me
to compose the network evaluation.
CHAPTER III: DESIGN OF THE EXPERT SYSTEM
This chapter deals with the design of my expert system; this
design is divided in two parts: the former is the construction of the knowledge
base, and the last is the implementation of the application.
III.1. Description of the knowledge base
The knowledge base is a part of an expert system containing
the collection of information, particularly rules and facts, which constitute
the domain of competence of the system. It contains the knowledge which allows
the inference mechanism to make conclusions; those are answers of the expert
system to the special consultation of the user.
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