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Tech Primer
802.11n
 The
increasing need for mobility and the increasing number of applications running
on wireless networks are giving rise to introduction of new technologies to
support the growth of the wireless revolution. The next great leap in wireless
technology delivers on the three most important elements of networking—greater
performance, more range, and improved reliability. At the same time, while devising
new approaches to boost performance, coexistence with existing 802.11a/b/g legacy
devices is required. All of these areas must be addressed while considering
practical and effective implementations for cost-sensitive market segments.
The evolution of 802.11
In response to growing demand for higher-performance wireless
local area networks (WLANs), the Institute of Electrical and Electronics Engineers
- Standards Association (IEEE-SA) approved the creation of the IEEE 802.11 Task
Group N (802.11 TGn) during the second half of 2003. The scope of TGn’s
objective is to define modifications to the Physical Layer and Media Access
Control Layer (PHY/MAC) that deliver a minimum of 100 megabit-per-second (Mbps)
throughput at the MAC service access point (SAP).
This minimum throughput requirement represents an approximate
4x leap in WLAN throughput performance compared to the 802.11a/g networks. TGn’s
purpose for this next step in WLAN performance is to improve the user experience
with existing WLAN applications while enabling new applications and market segments.
At the same time, TGn expects a smooth adoption transition by requiring backward
compatibility with existing IEEE WLAN legacy solutions (802.11a/b/g).
Coexisting with Wi-Fi
The IEEE TGn requires backward compatibility with 802.11a/b/g
devices. Intel expects that legacy 802.11b devices will coexist, and legacy
802.11a/g devices will interoperate with 802.11n devices when operating in the
same band and channel. This means 802.11n will need to support 20 MHz channels
for backward compatibility.
Intel has also been responsible for technical submissions
to TGn on MAC and PHY technologies as well as performance measurement and simulation
methods. Through all of these efforts, Intel and other industry leaders will
jointly develop and submit a complete IEEE TGn proposal for the IEEE 802.11n
standard.
Apple is implementing this new technology in most of its
latest computers, Apple TV, and AirPort Extreme Base Station. These new products
use AirPort Extreme wireless technology that is based upon the IEEE 802.11n
draft specification. Among its key innovations, 802.11n adds a technology called
multiple-input multiple-output (MIMO), a signal processing and smart antenna
technique for transmitting multiple data streams through multiple antennas.
802.11n product availability
Wi-Fi certified 802.11n draft 2.0 products have been tested
for interoperability across vendors, adhering to WPA2 (Wi-Fi Protected Access)
security protocols, and backward compatibility with more than 3,500 Wi-Fi certified
802.11n a/b/g products. Products based on the new IEEE 802.11n draft deliver
up to five times the throughput and up to twice the range of those based on
previous standards, enabling a wide range of content-rich applications, and
delivering those applications over a larger footprint. With a strong pipeline
of products already scheduled for certification testing, the Alliance expects
very high demand for certification testing.
—Varun Aggarwal
For more information, visit:www.wi-fi.org/pressroom_overview.php?newsid=574
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