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Issue
25 - September 2000
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Wireless
Versus Fixed Network Connection
By
S. K. Tsui
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If you watch closely
on campus, you will see more and more students use portable notebooks
to browse on the Internet, register courses or check e-mail in
public areas like the Library, Student Canteen, the 4/F Mall and
Covered Terrace. One may begin to ask how these notebooks get
connected to the network without the fuss of wiring them to specific
network points. The answer is the Wireless Local Area Network
(WLAN). To be exact, it is a flexible data communication system
using electro-magnetic waves (radio or infrared) to transmit and
receive data over the air. It can be integrated with the existing
wired network seamlessly and easily so that users can enjoy network
computing without the physical constraint of looking for a network
port to plug in.
Advantages of WLAN
Comparing with the traditional wired
networks, WLAN has the following advantages:
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Freedom of Mobility
WLAN users can access to real-time information in most areas
inside the campus. This mobility and convenience are not possible
or very hard to achieve with wired networks.
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Fast and Easy Installation
Installing WLAN is comparatively fast and easy, and we can
eliminate the need to lay cables through walls and ceilings.
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Installation Flexibility and
Scalability
Using wireless technology, we can extend the campus network
to those areas which are hard for cables to reach.
In some circumstances, we need additional
or temporary network points at some locations where wiring is
not appropriate for specific functions. With WLAN, network installation
can be easy and instant without the need to physically lay cables
through floors and ceilings.
Disadvantages of WLAN
Although the WLAN provides most of
the functionality of the wired LANs, it has the following disadvantages:
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High initial cost
The initial cost of wireless devices is much higher than that
of the traditional network devices. For example, a WLAN card
costs 3 to 10 times more than that of a wired LAN card.
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Limited bandwidth
We use wired LAN for speed and WLAN for convenience. Typically,
a WLAN Access Point (AP) of IEEE 802.11b standard can provide
a maximum data rate of shared 11Mbps to its clients while
the traditional Ethernet can provide 10 or 100 Mbps to each
client. Therefore, more APs have to be installed in the same
location to increase the throughput. Maximum of 3 APs operating
at different channels can provide up to 33 Mbps aggregate
bandwidth.
Due to the limited
bandwidth provided and the fact that many users share the same
bandwidth, WLAN is not suitable for bandwidth intensive applications
such as multimedia and video applications.
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Limited coverage
In our environment, the coverage of a single Access Point
(AP) is about 10 - 50 meters in radius in a closed office
depending on the barriers and partitions used. More APs have
to be installed to cover larger area.
Summary
The WLAN is not a replacement for
the wired network yet. Due to its limited bandwidth, we are currently
using it as a supplement to the traditional network to provide
flexibility and mobility to our users. As new technology is developing,
high-speed products will be available soon. It is now becoming
more and more popular and we can foresee that the WLAN will have
a very brilliant future ahead.
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