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Unformatted text preview: nto several sub-channels, each at a different
frequency. This boosts bandwidth by letting a system carry several transmissions
at the same time. Radio-router systems offer a maximum throughput of 1.5 Mbps.
OFDM, unlike traditional FDM, uses signal modulation and demodulation
techniques, as well as orthogonal placement of I adjacent channels, to minimize
interference. Multihop Wireless Networks
In most wireless network environments, the radio channel is used to connect the
mobile equipment to a base station in a single hop. The base station itself is
connected to a wired infrastructure. Consider an environment f where there is no
wired infrastructure yet connectivity must be maintained among users who can
move around arbitrarily and can at times not be in direct transmission range of
each other. Multihop wireless networks, also known as instant infrastructure
systems, are designed to provide wireless communications capability in such
I Instant infrastructure systems play an important role in wireless communication
because due to transmitted power constraints, not all radios are within the range of each other, and packets may need to be relayed from one radio to another on their
way to their intended destinations. These systems, however, are more complex to
design and manage than traditional single-hop, centrally controlled systems. This
is mainly because a fully implemented multihop system needs to have complete
support for multimedia, multihopping, and mobility features.
Wireless Application Protocol (WAP)
We saw in the discussion above that many different wireless access technologies
exist that are not interoperable. Designing and building networks and applications
for each technology would certainly be a very difficult job for developers. With
the proliferation of the Internet and wireless communications devices, Internet
access using mobile devices has become important for anywhere, anytime
information access capability. However, redesigning of all web sites to support
downloading of information by mobile user...
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This document was uploaded on 04/07/2014.
- Spring '14