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Unformatted text preview: ays operate at the top three layers of the OSI model (session, presentation,
and application). They are the most sophisticated internetworking tools and are
used for interconnecting dissimilar networks that use different communication protocols. That is, gateways are used to interconnect networks that are built on
totally different communications architectures. For instance, a gateway may be
used to interconnect two networks, one of which uses the IP suite and the other
uses the SNA protocol suite.
Since networks interconnected by a gateway use dissimilar protocols, protocol
conversion is the major job performed by gateways. Additionally, gateways
sometimes also perform routing functions.
One of the most challenging and interesting recent trends in the computer and
communications industries is the integration of wireless communications and
computing. The resulting network is referred to as a wireless computing systems.
A wireless computing system enhances the functionality of computing equipment
by freeing communication from the location constraints of the wired computing
Types of Wireless Computing Systems
Wireless computing systems can be broadly classified into the following two
1. Fixed wireless systems. These wireless computing systems support little or
no mobility of the computing equipment associated with the wireless network. For
example, a LAN can be set up using wireless technology to get rid of the hassles
of laying cables. The LAN will work as a conventional wired LAN except for the
difference that it does not need any cabling to be carried out.
Mobile wireless systems.
These wireless computing systems support
mobility of the computing equipment, which the users use to access the resources
associated with the wireless network. In turn, these systems support mobility of
users and allow the mobile users to access information-from anywhere and at
The resulting computing environment, which is often called mobile
computing or nomadic computing, no. longer requires a user to maintain a fixed
position in the network and enables almost unrestricted user mobility. Typical
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- Spring '14