Technology Trends
Standards, Standards, and More Standards: At present, globally there are two
main types of WLAN–802.11a and 802.11b–based on the standards established by
the Institute of Electrical and Electronics Engineers (IEEE). The latter has
been around for years and is the most widely adopted, while the former was
introduced more recently and is in the nascent stage of acceptance by equipment
vendors. The significant differences between the two are that 802.11a offers a
faster connection than 802.11b and operates on spectrum that is less cluttered
than 802.11b. Then, there are newer variations on these two offerings, such as
802.11g, 802.11e and 802.11i, which in essence are enhancements to the existing
standards, offering greater compatibility, flexibility and security to Wi-Fi
networks. Theoretically, 802.11b offers a throughput of 11 Mbps (though for all
practical purposes, it is closer to 5.5 Mbps) and operates on the 2.4 GHz band,
while 802.11a offers a connection speed of 54 Mbps and runs on the 5 GHz band.
In India, the 802.11b variant of WLAN is permitted for use inside campuses
without a licence.
l 802.11g: The 802.11g
standard is a combination technology that is compatible with 802.11b and uses
the 2.4 GHz band with a data rate comparable to that of 802.11a. As 802.11a runs
on the 5 GHz band, which is regulated in India and is unlikely to be offered to
private enterprises for use at least in the near future, its deployment is out
of the question. So, enterprises can look forward to deploying 802.11g. Besides
offering five times more throughput than 802.11b, 802.11g is also backwards
compatible with 802.11b, enabling an access point built for 802.11g to connect
802.11b-based devices also. A laptop with 802.11b capability and a tablet PC
with 802.11g, for instance, can thus use the same base station.
l 802.11b: 802.11b
wireless networking consists of the stations or hubs, access points, and ports.
A station (STA) is a network node that is equipped with a wireless network
device. A personal computer with a wireless network adapter is known as a
wireless client (laptops using wireless PCI cards). Wireless clients can
communicate directly with each other or through a wireless access point (AP).
Wireless clients are mobile. A wireless access point is a wireless network node
that acts as a bridge between STAs and a wired network. The wireless AP is
similar to a cellular phone network’s base station.
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Wireless clients communicate with both the wired network and other wireless
clients through wireless Aps, which are not mobile and act as peripheral bridge
devices that extend a wired network. A port is a channel of a device that can
support a single point-to-point connection. For IEEE 802.11b, a port is an
association, a logical entity, over which a single wireless connection is made.
A typical wireless client with a single wireless network adapter has one port
and can support only one wireless connection. A typical wireless AP has multiple
ports and can simultaneously support multiple wireless connections. The logical
connection between a port on the wireless client and the port on a wireless AP
is a point-to-point bridged LAN segment–similar to an Ethernet-based network
client that is connected to an Ethernet switch.
Buying tips
regulatory guidelines governing the deployment of WLAN in India. For the
record, 802.11b WLAN can be set up without government permission within the
campus. The moment an enterprise decides to cross its building or campus, it
needs to ask the government for a license. Also, regulations in India
specifically permit the use of only 802.11b. The usage of 802.11a or 802.11g
would require government clearance.
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- Radio Survey: Enterprises must carry out a radio survey of the area
it wants its WLAN to cover. A survey is important for two reasons: one, it
will help an enterprise design its network better and two, it would ensure
that one network’s signal does not interfere with other networks in and
around the proposed deployment site. An enterprise must ensure that radio
signals do not cross the defined limits within which it wants the WLAN to
work. - Site Survey and Network Design: Once the radio survey is done, the
next important consideration should be the interior design structure of the
site where WLAN is going to be set up. WLAN systems use radio frequencies (RF).
And the distance over which RF waves can travel is not the function of the
product alone. It also depends on the propagation path of RF. Even though RF
waves are capable of penetrating most indoor walls and other physical
obstacles, their range of coverage does depend on the indoor architecture of
a building. In open spaces, each wireless LAN access hub can cover up to 300
feet, while in places with physical barriers like walls, a hub may be
effective only up to 130 feet. This would naturally mean that access points
should be placed strategically so as to overcome all physical barriers
inside the building. Otherwise, users will not be able to enjoy the
advantage of mobility or roam around freely in a building with their
connected laptops. The enterprise should get the site survey conducted for
verifying the coverage and estimating the number of WLAN access points
required at the premise. This would depend on the topology of the location
and the amount of throughput required.
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- Do You Really Need WLAN?: In other words, an enterprise needs to
know why it should deploy WLAN. WLAN can be more beneficial and productive
if it is being deployed for running applications rather than plain mobile
Internet access within the campus. Also, if an enterprise knows beforehand
what it will do with WLAN, it will be in a better position to calculate the
RoI on it. - Integration with Existing LAN: How an enterprise integrates WLAN
with the existing wired LAN is also very important. The integration should
be such that it facilitates seamless movement of a user from WLAN to wired
LAN and vice versa. Also, services should be enabled on the WLAN in the same
way as they have been on wired LAN. - Security Issues: Wireless LAN networks are prone to unauthorized
access, breaking of encryption, and loss of data integrity. And except for a
few of the more well-known vendors of WLAN products and solutions, many do
not use any accepted security standards. So, an enterprise must ensure that
it deploys only those WLAN products that adhere to widely accepted and
proven security standards. - QoS: An enterprise must also ensure that any network that it
deploys should have QoS built in. Among other things, this should mean that
the WLAN must allow an enterprise to prioritize voice, data, and video on
the network. Also, the network should be scalable. - Manageability: Managing a WLAN network can be a challenge as the
network grows and adds more and more users. An enterprise must manage WLAN
in the same way it manages its traditional LAN. In other words, it must look
at managing both WLAN and wired LAN together from the same platform. - Throughput: Practically 802.11b does not support more than 5.5 Mbps
bandwidth. Moreover, in a multi-user environment, this 5.5 Mbps bandwidth is
shared among all the users and is not dedicated to a single user. Besides,
as the user keeps moving away from a wireless LAN access hub, the bandwidth
output keeps on decreasing. Naturally, all this rules out high-bandwidth
applications. WLAN throughput is sufficient for applications like electronic
mail exchange, access to shared peripherals like printers, Internet access,
and access to multi-user databases and applications.
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