|
History
In 1970 University of Hawaii, under the leadership of Norman
Abramson, developed the world’s first computer communication
network using low-cost ham-like radios, named ALOHA net. The
bi-directional star topology of the system included seven
computers deployed over four islands to communicate with the
central computer on the Oahu Island without using phone lines.
"In 1979, F.R. Gfeller and U. Bapst published a paper in the
IEEE Proceedings reporting an experimental wireless local area
network using diffused infrared communications. Shortly
thereafter, in 1980, P. Ferrert reported on an experimental
application of a single code spread spectrum radio for wireless
terminal communications in the IEEE National Telecommunications
Conference. In 1984, a comparison between Infrared and CDMA
spread spectrum communications for wireless office information
networks was published by Kaveh Pahlavan in IEEE Computer
Networking Symposium which appeared later in the IEEE
Communication Society Magazine. In May 1985, the efforts of
Marcus led the FCC to announce experimental ISM bands for
commercial application of spread spectrum technology. Later on,
M. Kavehrad reported on an experimental wireless PBX system
using code division multiple access. These efforts prompted
significant industrial activities in the development of a new
generation of wireless local area networks and it updated
several old discussions in the portable and mobile radio
industry.The
first generation of wireless data modems was developed in the
early 1980's by amateur radio operators. They added a voice band
data communication modem, with data rates below 9600 bit/s, to
an existing short distance radio system, typically in the two
meter amateur band. The second generation of wireless modems was
developed immediately after the FCC announcement in the
experimental bands for non-military use of the spread spectrum
technology. These modems provided data rates on the order of
hundreds of Gbbit/s.
The third generation of wireless modem [then] aimed at
compatibility with the existing LANs with data rates on the
order of Mbit/s. Several companies developed the third
generation products with data rates above 1 Mbit/s and a couple
of products had already been announced by the time of the first
IEEE Workshop on Wireless LAN.
Benefits
The popularity of wireless LANs is a testament primarily to
their convenience, cost efficiency, and ease of integration with
other networks and network components. The majority of computers
sold to consumers today come pre-equipped with all necessary
wireless LAN technology.
Disadvantages
Wireless LAN technology, while replete with the conveniences and
advantages described above, has its share of downfalls. For a
given networking situation, wireless LANs may not be desirable
for a number of reasons. Most of these have to do with the
inherent limitations of the technology.
Security: Wireless LAN
transceivers are designed to serve computers throughout a structure with
uninterrupted service using radio frequencies. Because of space
and cost, the antennas typically present on wireless networking
cards in the end computers are generally relatively poor. In
order to properly receive signals using such limited antennas
throughout even a modest area, the wireless LAN transceiver
utilizes a fairly considerable amount of power.
Reliability:
Like any radio frequency transmission, wireless networking signals are
subject to a wide variety of interference, as well as complex
propagation effects (such as multipath, or especially in this
case Rician fading) that are beyond the control of the network
administrator. In the case of typical networks, modulation is
achieved by complicated forms of phase-shift keying (PSK) or
quadrature amplitude modulation (QAM), making interference and
propagation effects all the more disturbing. As a result,
important network resources such as servers are rarely connected
wirelessly..
Speed:
The speed on most wireless networks (typically 1-108 Mbit/s) is
reasonably slow compared to the slowest common wired networks
(100 Mbit/s up to several Gbit/s). There are also performance
issues caused by TCP and its built-in congestion avoidance. For
most users, however, this observation is irrelevant since the
speed bottleneck is not in the wireless routing but rather in
the outside network connectivity itself. For example, the
maximum ADSL throughput (usually 8 Mbit/s or less) offered by
telecommunications companies to general-purpose customers is
already far slower than the slowest wireless network to which it
is typically connected. That is to say, in most environments, a
wireless network running at its slowest speed is still faster
than the internet connection serving it in the first place.
However, in specialized environments, the throughput of a wired
network might be necessary. Newer standards such as 802.11n are
addressing this limitation and will support peak throughputs in
the range of 100-200 Mbit/s.
"More History of The Computer are to come Soon"

"Coming Soon to this Website"


Just Click on Motherboard Banner Above to Return. |