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Unformatted text preview: used in mobile wireless systems includes smart phones,
personal digital assistants (PDAs), and pagers with Internet access.
Note that mobile users do not necessarily need to use wireless interfaces and
wireless interfaces do not necessarily support mobility. A mobile user can simply
connect to fixed networks using wired interfaces as he/she moves. Likewise, a fixed-location user might use a wireless interface (via a LAN) while
sitting in an office. Therefore, mobile and wireless computing systems are not the
same even though there is considerable overlap.
Issues in Wireless Computing Systems
Wireless computing systems communicate by modulating radio waves or pulsing
infrared light. Wireless communication is linked to the wired network
infrastructure by stationary transceivers. The area covered by an individual
transceiver's signal is known as a cell. Cell sizes vary widely. For instance, an
infrared transceiver can cover a small meeting room, a cellular phone transceiver
has a range of a few miles, and a satellite beam can cover an area more than 400
miles in diameter.
The successful use of wireless computing systems faces several challenges. The
important ones among them are as follows:
Lower bandwidths. Wireless communication is characterized by lower
bandwidths. That is, the channel capacity typically available in wireless systems
is much lower than what is available in wired networks due to the limited
spectrum available, power restrictions, and noise levels.
Variable bandwidths. In case of mobile wireless systems, the limited
bandwidth that is available is also variable depending on location. Channel reuse
must, therefore, be an integral part of the system in order to provide service to as
many potential subscribers as possible.
Higher error rates. Noise and interference have more impact on wireless
computing systems than for wired computing systems. This, in turn, increases
communication latency resulting from retransmissions, retransmission time-out
delays, and error-correction protocol processing.
4. Increased security concerns. Security is a greater concern in...
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- Spring '14