Information Technology Reference
In-Depth Information
organization of data items on single and parallel channel(s), application of index-
ing on single and parallel channel(s), data replication, data distribution, conflict, and
scheduling of data accesses are enumerated and analyzed in Section
3
. Solutions to
these issues with respect to the
network latency;
access latency; and
power management
are addressed and analyzed in Sections
4-8
. Finally, Section
9
concludes the chapter
and discusses some future research directions.
2.
Mobile Computing
The mobile computing environment is based on wireless communication that al-
lows the user to access information anywhere at anytime without any direct physical
link to the network. The wireless network (
Fig. 1
) is composed of:
A number of network servers enhanced with wireless transceivers—mobile sup-
port stations (MSS)—scattered along a geographical area; and
A varying number of mobile hosts (MHs) free to move at will.
The MSS provides a link between the wireless network and the wired network.
The link between a MSS and the wired network could be either wireless (shown as
dashed line) or wire based. The area covered by the individual transceiver is referred
to as a cell. The size of the area covered by each cell varies widely, depending on the
technology being used.
The MH is relatively small, light weight, and portable. It is designed to preserve
space and energy. Most of the time, the MH relies on temporary power sources such
as batteries as its main power source. To save energy, the MH is designed to operate
in different operational modes (i.e., active doze, sleep, nap) that consume different
levels of power.
2 . 1
W i r e l e s s C o m m u n i c a t i o n Te c h n o l o g y
Wireless communication is accomplished via modulating radio waves or pulsing
infrared light. A variety of infrastructures such as; cellular networks, wireless LANs,
paging networks, and satellite networks rely on modulating radio waves.
