Introduction Technology Organizations Pros and Cons FAQs Resources
Frequently Asked Questions
How a wireless network operates?
Why are there so many wireless LAN industry
organizations?
How a
wireless network operates?
A
wireless network, often referred to as a Wireless Local Area Network (wireless
LAN or WLAN), is a data communication system in which the data is transferred
between devices via radio waves. Hence, wireless networking operates
qualitatively the same as a wired network except that the data is transmitted
via electromagnetic radio waves, using the air to transmit data instead of fixed
wires planted throughout the structure. This approach to networking
dramatically increases the flexibility of networking devices since the user is
no longer required to be fixed to a specific location where the wire can be
plugged into the computer. With wireless networking the user can be anywhere,
increasing user mobility by adding mobility to data access. A side effect is
that high-speed wireless networking minimizes the need and cost, for wired
networks and connections, offering a low cost, high capacity replacement for
fixed networks in several areas.
Over
the last several years wireless LANs have grown in popularity in several
markets including manufacturing, retail, office / corporate, and healthcare. Adding
mobility to the access of data in these places can introduce significant
operating efficiencies and productivity gains. As the data rate and capacity of
wireless LAN increases it is becoming more widely adopted as both an extension
to the fixed LAN, as well as a complete replacement. The market for these
devices and systems reached $1 billion in annual revenues in 2000 [source: IDC
and Cahners In-Stat].
Typical
wireless LAN implementations employ a radio frequency (RF) or infrared (IR)
modem attached to a laptop or other computer device. Data is transmitted
between this network "node", or mobile terminal (MT), and a wireless
access point (AP) that transfers the data to the desired device or system using
standardized networking protocols. The air is the interface for the wireless
network and the devices are physically disconnected from the core network. The
AP can support multiple users at once and can reside at any node on the network
or as a separate entity, acting as a gateway between the MTs, the wireless
clients, and the wired network. The following picture shows a schematic of a
corporate wireless LAN where laptops are interconnected via a wireless
connection to each other, and to the fixed network.
Current
wireless networking standards provide the same features and benefits as current
fixed networking approaches such as Ethernet.
Why
5GHz?
With
the arrival of Bluetooth, the issue of coexistence for all the wireless
protocols at 2.4 GHz has taken center stage and has been the focus of many
roundtable discussions. The main reason for that is that the 2.4GHz
spectrum is a mess, it is extremely crowded and Bluetooth will only add to the
problem, all sorts of equipment from appliances such as microwaves, to cordless
phones, to 802.11b based wireless LANs and now Bluetooth share the 2.4GHz
spectrum, and interference is rapidly becoming the main topic of discussion
when 2.4GHz comes up. While you will find many experts who stand by the
idea that interference between these devices can be reduced by not having them
operate right next to each other and that under normal operation in the same
room the various wireless devices should coexist, somehow that is not all that
comforting to someone planning to use Bluetooth to synchronize their 802.11b
wireless laptop with their PDA.
Therefore,
the move is on to 5 GHz, and for various reasons, one of which is that it's
assigned to be used specifically for broadband data service. ISM service is
relegated to the upper limits. In addition, there is greater bandwidth at 5
GHz. For example, 802.11a uses 12 non-overlapping 20-MHz channels, while
802.11b uses three channels with distances between center frequencies of 25
MHz. This translates to a raw data throughput for 802.11a of between 6 and 54
Mbps, depending on the modulation scheme used (binary phase-shift keying,
quadrature phase-shift keying or quadrature amplitude modulation). At present,
802.11b is call for a maximum bandwidth of 11 Mbps.
While
the raw data maximum of both HiperLAN2 and 802.11a is 54 Mbps, actual payload
rates are expected to be about half that, which will still satisfy the need for
full MPEG video, high-speed Internet access and home/office and public access
within buildings like airports. That will even be true as the raw rate jumps to
100 Mbps which is expected to happen further down the road for both standards.
The
in-building scenario is important, since it relates to the one caveat with
5-GHz operation. WLANs operating at 5 GHz must share the band with satellite
uplink service; as a result 5-GHz operation is limited to indoor service in the
Why are
there so many wireless LAN industry organizations?
[By
Greg DiCillo, managing director of the Wireless LAN Association (WLANA)]
You
may have noticed that the wireless LAN industry is growing up. No longer an
infant in size or scope, the industry has moved well into its teenage years.
What was once an industry serving niche application is now providing solutions
in mainstream and emerging networking segments including the enterprise, the
small office, and the home. As the industry matures and more customers see
wireless LANs as viable solutions to their networking needs, more and varied
applications arise, offering wireless LAN vendors new technological challenges.
An
outgrowth of the new challenges is the need to solve these newly found
opportunities. In some cases, solutions can be provided utilizing existing
technology, while others may require new or different means. To address some of
the bigger challenges vendors form alliances, consortiums, or forums. This has
happened throughout the industry as technologies and market needs emerge.
The
same phenomenon is occurring in the area of wireless LAN technology as
indicated by the alphabet soup of new alliances, consortiums, forums, and
associations. They run the gamut from educational organizations to technology
alliances. All are meant to deliver solutions to meet the needs of the marketplace. To
help make sense of it all, we will attempt to create some general categories
for wireless LAN organizations, offer a definition, and place the various
wireless LAN organizations in one of the categories. This is by no means
simple.
For
purposes of brevity and simplicity, we can offer three categories of
organizations: technology alliances, standards bodies, industry associations:
1.
Technology
- Bluetooth SIG – Based on the
Bluetooth™ specification for a small form-factor, low-cost radio solution
providing links between mobile computers, mobile phones, and other
portable handheld devices, and connectivity to the Internet;
- HiperLAN1 - HiperLAN Alliance and HiperLAN2 Global Forum – promotional
bodies for (high performance radio local area network) in
- HomeRF – Based on a specification for wireless
communications in the home called the shared wireless access protocol
(SWAP). The HomeRF Working Group (HRFWG) was formed to provide the
foundation for a broad range of interoperable consumer devices by
establishing an open industry specification for wireless digital
communication between PCs and consumer electronic devices anywhere in and
around the home;
- OFDM - Wi-LAN is based primarily on
a patented wide-band orthogonal frequency division multiplexing (W-OFDM);
- WLI Forum - The WLIF established OpenAir
as an interoperable wireless LAN standard in 1996, and the standard is
available to any company that joins the forum. The OpenAir standard is
based on Proxim’s RangeLAN2, which is a 2.4 GHz frequency-hopping
spread-spectrum radio frequency (RF) technology; and
- WECA - WECA’s mission is to
certify interoperability of Wi-FiTM (IEEE 802.11 High Rate) wireless LAN
products and to promote Wi-FiTM as the standard for wireless LAN
deployments across all market segments.
2.
Standards bodies create technical specifications (industry standard) through a
process open to all companies. Examples of standards bodies include:
- IEEE (Institute of
Electrical and Electronics Engineers); and
- ETSI (European Telecommunications
Standards Institute).
3.
Industry association. An industry association (trade association) can best be
characterized as an organization created to promote the growth of the industry
through promotion and education, providing objective information on the
industry in general, technologies, trends, organizations, and opportunities, regardless
of technology. The Wireless LAN Association
(WLANA) with its mission to help foster overall industry growth through
education can be characterized as an industry trade association.
The
good news is that these organizations can only blossom due to increased demand
for wireless LAN products. The fact that these organizations exist gives
testament to the value wireless LAN technology brings to the market.
Organizations like these promote competition and technological advancement,
which means better solutions for wireless LAN customers and increased growth
for the industry. While the number of organizations out there may confuse many,
each has a mission to provide the best wireless LAN solutions for the market. Hopefully
this helps you better understand the state of the industry and help you make
good wireless LAN decisions as you plan your wireless IT strategy. Ultimately,
the marketplace will decide the value of each organization.
More
HiperLAN2 and other
WLANs:
http://www.hiperlan2.com/faq.asp
http://www.hiperlan.uk.com/faqs/FAQ.htm
OFDM:
http://www.ofdm-forum.com/index.asp?ID=94