- the term is most commonly use to refer to a telecommunications network whose interconnections between nodes is implemented without the use of wires, such as a computer network.
- Wireless telecommunications networks are generally implemented with some type of information transmission system that uses electromagnetic waves, such as radio waves, for the carrier .
- Wireless communication involves
• radio frequency
communication
• microwave communication, for example long‐range line of sight via highly directional antennas
or short line‐of‐antennas, short range communication
• infrared (IR) short‐range
communication, for example from remote controls or via IRDA
- Applications may involve point‐to‐point communication, point‐to‐multipoint communication, broadcasting ,cellular networks and other wireless networks.
*Devices commonly use wireless networking technologies:
portable computers,
desktop computers
hand‐held computers,
personal digital assistants (PDAs),
cellular phones,
pen‐based computers,
pagers, GPS etc.
*Type of
Wireless Network:
Wireless wide area networks (WWANs)
Wireless metropolitan area networks (WMANs)
Wireless local area networks (WLANs)
Wireless personal area networks (WPANs)
- TERRESTRIAL MICROWAVE
http://en.wikipedia.org/wiki/Microwave
-high antenna, longer sight distance
-high antenna, longer sight distance
-signal: 1 way direction at a time
-type of antenna:
- parabolic dish : give greatest range for signal & based on geometry of parabola..
- horn:gigantic scoop
- SATELITE
Satellite Internet comes in two flavors:
- One-way systems use a conventional Internet link (usually telephone) for upload and the satellite link for high-speed download.
- Two-way systems add a transmitter to the satellite modem and upload via the satellite.
Satellite speeds are typically in the 0.5 to 2.0 Mbps
range for download, and approximately 1/10th of the download speed for
upload in a two-way system. In addition, there is about a 400 millisecond latency
involved in sending a signal from a base-station to a satellite and
back to Earth. Consequently, satellite connections aren't fully
competitive with other home broadband Internet options.
- Uplink = transmission from earth --> satellite
- Downlink = transmission from satellite --> earth
- WI‐FI
the
underlying technology of wireless local area networks (WLAN)
based on the IEEE 802.11 specifications.
used for mobile computing devices, such as laptops
in LANs,increasingly used for more services, including Internet and VoIP phone
access, gaming, and basic connectivity of consumer electronics such as
televisions and DVD players, or digital cameras
Frequency 2.4 GHz
*CELLULAR PHONE
- 1G
1G is short
for first‐generation wireless telephone
technology.
This generation of phones and networks is
represented
by the brick‐sized analog phones
introduced
in the 1980’s. Subsequent numbers refer
to newer and
upcoming technology.
- 2G
2G phones
use digital networks. Going all‐digital allowed for
the
introduction of digital data services, such as SMS and
email. 2G
networks and their digital nature also made it more
difficult to
eavesdrop on mobile phone calls.
- 3G
3G networks
are an in between standard. 3G is seen more as
pre4G
instead of a standard of its own. The advantage 3G
networks
have over 2G networks is speed. 3G networks are
built to
handle the needs of today’s wireless users. This
standard of
wireless networks increases the speed of internet
browsing,
picture and video messaging, and handheld GPS
use.
- 4G
4G (AKA
Beyond 3G) is like the other generations in that its
advantage
lies in promised increased speeds in data
transmission.
There is currently no formal definition for 4G,
but there
are objectives. One of these objectives is for 4G to
become a
fully IP‐based system, much like modern computer
networks.
The supposed speeds for 4G will be between 100
Mbit/s and 1
Gbit/s.
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