ENTERPRISE WLAN: Easy and Convenient

WLAN is now mainstream in India as more and more enterprises deploy it and
discover that it is a productivity tool. Convenient and easy to deploy, WLAN is
economical too. And, the same wireless network can be used for voice and video
applications.

Though 802.11b-based WLANs are still the most common, 802.11g is the current
flavour. Not only does 802.11g offer more throughput and better performance than
802.11b; it is backward compatible with 802.11b.

Technology Options

- 802.11b: The 802.11b offers a throughput of 11 Mbps theoretically
(practically it is 5.5 Mbps) and operates in the 2.4 GHz band. The standard has
a rated operating range of 100 meters. In the 2.4 GHz ISM band, there is about
80 MHz of useable spectrum. Hence, in a radius of 100 meters, three 22 MHz,
802.11b systems can operate on a non-interfering basis, each offering speeds up
to of 11 Mbps.

- 802.11g: The 802.11g standard also uses the 2.4 GHz band,
with a data rate comparable to that of 802.11a. Besides offering five times more
throughput then 802.11b, 802.11g is backward compatible with 802.11b, enabling
an access points built for 802.11g to connect 802.11b.

- 802.11a: The 802.11a standard offers connections at speed of
54 Mbps and runs on the 5 GHz band. It is projected to have an operating range
of 50 meters.

With the wide acceptance of competing 802.11g standard supporting similar
speeds and backward compatibility with 802.11b, has made 802.11a a not so
popular choice for WLAN deployment. With availability of Dual/tri mode AP's
supporting the 802.11a/b/g standards user can still weigh the benefits of each
standard and deploy combination of products in their network.

- 802.11n: Vendors are working on a new version named 802.11n
that would offer a minimum throughput of 100 Mbps (some vendors are trying to
for 500 Mbps to 630 Mbps). However, 802.11n-based WLAN is unlikely to reach
users until the beginning of 2006 as IEEE has still not finalized the standard
and the industry is almost vertically split on the specifics of standardization.

Components of a WLAN

-
The 802.11b/g wireless networking consists of 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 (i.e., laptops using wireless PCI cards or mobile chips).

- Wireless clients can communicate directly with each other or through
a wireless access point (AP).

- Wireless AP is a wireless network node that acts as a bridge between
STAs and a wired network. Wireless APs are similar to cellular phone networks'
base stations. Wireless clients communicate with both the wired network and
other wireless clients through the wireless AP. Wireless APs are not mobile. It
acts as a peripheral bridge device that extend the 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.

Challenges

-
As enterprises expand their WLAN networks and use them for voice
and video applications as well, these networks will throw up three key
challenges: achieving quality of service (QoS), ensuring security, and
interoperability with other wireless networks for hassle-free network
management.

- As of today, there is no built-in QoS in 802.11 networks, so quality
is only best effort. As far as plain data applications like e-mail or surfing
are concerned, best-effort services are enough. However, QoS would be important
for multimedia applications on 802.11 networks and other advanced applications
like VoIP over WLAN. Because they are delay- and throughput-sensitive, they
would require better traffic management and bandwidth assignment. Today, there
is no prioritization of traffic on Wi-Fi networks.

- IEEE's 802.11e standard, which is likely to be ratified by early
2005, is expected to take care of these QoS issues.

- Working on the standard, Wi-Fi Alliance has come up with Wi-Fi for
Multimedia (WMM) and started a program called Wi-Fi Certified for WMM that will
certify Wi-Fi products in terms of their QoS capabilities. According to a Wi-Fi
Alliance paper, WMM will add prioritized QoS capabilities to Wi-Fi networks and
optimize their performance when multiple, concurring applications (each with
different latency and throughput requirements) compete for network resources.

- There would be issues of seamless connectivity between different
WLANs and also between WLANs and wired LANs, as wireless networks grow in terms
of numbers and types.

- There would be issues relating to management and interoperability
between different protocols.

- Security has remained a key concern of enterprises, since the day
they began deploying WLANs. The Wi-Fi Alliance had, in September 2004, announced
the first round of products that are Wi-Fi Certified for the WPA2 (Wi-Fi
Protected Access 2) capability. WPA2 is based upon the IEEE's 802.11i
amendment to the 802.11 standard. Wi-Fi Alliance has said that products that are
Wi-Fi Certified for WPA will remain technically sound and secure. Products that
are certified for WPA2 give IT managers the assurance that the technology meets
interoperability standards and in turn, helps them manage support and deployment
costs.

Tips

- Regulatory guidelines: Both 802.11b and 802.11g can be deployed
without government's permission. The government also plans to de-license the 5
GHz band (for 802.11a) for indoor use. However, an official notification to this
effect is awaited.

- Radio survey: How an enterprise architectures the network is
very important. Carrying out a radio survey of the area to be covered by WLAN
would be the first step towards deploying a WLAN for optimum utilization. A
survey is important for two reasons: one, it helps 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.

- Site
survey: After radio survey, the other important consideration should be the
interior design structure of the site. WLAN systems use RF. And the distance
over which RF waves can travel is not a function of the product alone. It also
depends on the propagation path of RF. Even though RF waves can penetrating most
indoor walls and other physical obstacles, their range of coverage surely
depends on the indoor architecture of the building. In open spaces, each WLAN
access hub can cover up to 300 feet. While, with physical barriers-like walls a
hub could be effective in the range of 130 feet only. This would naturally mean
that access points are to be placed strategically so as to overcome the physical
barriers inside a building. Otherwise, users would 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 APs required at the premise. This
would depend on the topology of the location and the amount of throughput
required.

- Integrating existing LAN: How an enterprise integrates WLAN
with the existing wired LAN is very important. The integration should facilitate
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 the wired LAN.
Integration would also mean things like single password access for both wired
LAN and Wi-Fi.

- Security: WLAN networks are found prone to unauthorized
access, breaking of encryption, and loss of data integrity. And except some of
the well-known vendors, most do not use any accepted security standards. So
enterprises must ensure to deploy only those products that adhere to the
accepted and proven security standards.

- QoS: An enterprise must also ensure that the network should
have QoS built in. This should also mean that the WLAN must allow to prioritize
voice, data, and video on the network and the network be scalable.

- Manageability: Managing a WLAN could be a challenge as the
network grows and adds more users. Enterprises must manage WLAN in the same way
as the traditional LAN and both should be managed together from the same
platform.