WIRELESS LAN’S
Wireless
technologies differ in variety of dimensions, most notably in how much
bandwidth they provide and how far apart communicating nodes can be. Other
important differences include which part of the electromagnetic spectrum they
use (including whether it requires a license) and how much power they consume.
Four prominent wireless technologies:
► Blue
tooth
► Wi-Fi(more
formally known as 802.11)
► WiMAX(802.16)
► Third
generation or 3Gcellular wireless.
The most
widely used wireless links today are usually asymmetric, that is, the two
endpoints are usually different kinds of nodes.
BASE
STATION, usually has no mobility, but has a wired (or at least high bandwidth)
connection to the internet or other networks.
A “client
node” is often mobile, and relies on its link to the base station for all its
communication with other nodes. Wireless communication naturally supports point
to multipoint communication, because radio waves sent by one device can be
simultaneously received by many devices. However, it is often useful to create
a point to point link abstraction for higher layer protocols.
This
topology implies three qualitatively different levels of mobility. The first
level is no mobility, such as when a receiver must be in a fixed location to
receive a directional transmission from the base station, as is the case with
the initial version of WiMAX. The second level is mobility within the range of
a base, as is the case with Bluetooth. The third level is mobility between
bases, as is the case with cell phones and Wi-Fi.
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