802.11n is a high-throughput update to 802.11 with increased robustness and coverage.
In response to a growing market demand for higher-performance WLANs, the IEEE formed the TGn Task Group within the 802.11 Working Group to develop a new amendment to the 802.11 standard, called 802.11n. Formed in September 2003, TGn's objective was to define modifications to the 802.11 standard that deliver a minimum of 100 Mbps of application data throughput, with increased robustness and range. This minimum throughput requirement represents an increase of four to five times over today's 802.11a/g networks. At the same time, a smooth transition was planned by requiring backward compatibility with existing 802.11a/b/g solutions.
Formal Ratification of 802.11n Planned for June 2009
TGn has made steady progress since its inception in 2003, but as with most complex technologies, the process of ratifying a standard takes several years. With so much interest in boosting wireless network performance and capacity, 32 different proposals were initially submitted, and TGn struggled to agree upon a single proposal that could be developed into a standard. In January 2005, the field was narrowed down to two proposals from the TGn Sync and WWiSE consortiums, and for most of 2005 the task group was deadlocked between these two proposals.
In October 2005, Cisco® and 26 other companies formed the Enhanced Wireless Consortium (EWC) to accelerate the 802.11n standard development process. Cisco played a primary role in the EWC to help break the deadlock between TGn Sync and WWiSE, and in January 2006, the IEEE voted to accept the 802.11n proposal submitted by the EWC as the starting point for the 802.11n standard.
Since then, TGn has made significant progress and the task group continues to work through the many details necessary to deliver a robust standard. TGn currently plans to complete their work and submit the 802.11n standard to the IEEE Standards Board for ratification in June 2009.
Cisco has been fully supportive of this effort as an active member of TGn since its inception.
In late 2006, "pre-draft 802.11n" products started appearing in the consumer market. Unfortunately, many of these products did not perform well and were not interoperable. The underlying problem was that the draft standard at the time was relatively unstable, and the Wi-Fi Alliance had not yet started interoperability testing.
However, in early 2007, a ballot on 802.11n Draft 2.0 passed in the IEEE 802.11 Working Group with a super-majority of more than 75 percent. This was an important sign for convergence of the base features in the 802.11n standard development process.
The Wi-Fi Alliance used this indication of maturity to justify proceeding towards certification of the base features of 802.11n Draft 2.0. Cisco played a critical role in helping define the criteria for Wi-Fi 802.11n Draft 2.0 certification and participated extensively in the Wi-Fi plug fests to work through early interoperability issues.
After a long and extensive test cycle with products using radio chipsets from all of the major silicon vendors, including Intel, Marvell, Atheros, and Broadcom, the Wi-Fi Alliance decided to begin public certification. Because Cisco products demonstrated a wide range of interoperability in these early tests, the Cisco Aironet® 1250 Series Access Point was chosen as the only enterprise-class access point for the official Wi-Fi Alliance 802.11n Draft 2.0 test bed.
As part of the test bed, the Cisco Aironet 1250 Series is the benchmark against which all other 802.11n products are tested. In June 2007, the Wi-Fi Alliance began certifying 802.11n Draft 2.0 products and on 25 June 2007, the Cisco Aironet 1250 Series was the first enterprise access point to achieve Wi-Fi 802.11n Draft 2.0 certification. As of February 2008, over 200 products have been tested with the Cisco Aironet 1250 Series and have received Wi-Fi 802.11n Draft 2.0 certification.
Evaluating the Risks of Adopting 802.11n Draft 2.0
An important question for many people considering investing in solutions based on 802.11n Draft 2.0 is whether 802.11n Draft 2.0 products will be compatible with products based on the final ratified 802.11n standard. In the absence of a ratified standard, no responsible vendor can guarantee that Wi-Fi 802.11n Draft 2.0 certified products will result in compatibility with the final ratified standard. However, many industry experts believe compatibility at the core feature level will be achieved either directly or via software upgrades. The reasons for confidence in the future compatibility of products designed using the draft standard include the following:
• The core 802.11n Draft 2.0 features have been stable since early 2007, even after multiple rounds of balloting in the IEEE 802.11 Working Group.
• The Wi-Fi industry recognizes the importance of low-impact upgrades and so will avoid any changes to the 802.11n draft that requires hardware upgrades, unless absolutely necessary.
• The risk of hardware changes based on the need to ensure 802.11n Draft 2.0 systems are secure has been mitigated by the use of independent security reviews.
• The market success of 802.11n Draft 2.0, with over 200 devices certified by the Wi-Fi Alliance (as of February 2008) and over 17 million products forecast to be shipped in 2008, means products based on some future standard requiring a hardware upgrade would be unlikely to gain market traction.
As Table 1 shows, over 17 million 802.11n Draft 2.0 products will ship in 2008.
Table 1. Estimated Number of 802.11n Draft 2.0 Products Shipping in 2008
Installed Base
Estimated to Ship in 2008
11n clients
> 2,600,000
5,400,000
Enterprise 802.11n access points
> 15,000
230,000
Consumer 802.11n access points
> 4,000,000
12,000,000
TOTAL
> 6,615,000
17,630,000
Source: Dell'Oro Wireless LAN Report-3QCY07
The situation for the features not currently tested by the Wi-Fi Alliance's 802.11n Draft 2.0 certification program is less certain. Interoperability is not an issue because these noncore features are not tested and are mostly not implemented today. However, the same pressures apply to allow the use of new features without the need for hardware upgrades. In the unlikely event that a hardware upgrade is required, the modular nature of the Cisco Aironet 1250 Series Access Point allows simple field upgrades of the radio modules.
For many customers, the benefits of putting 802.11n Draft 2.0 to work today outweigh the risks (perceived and real). There are an increasing number of customers who are learning about the benefits of 802.11n Draft 2.0 first hand. For example:
• A large apparel retailer is improving the quality of its warehouse voice-over-wireless implementation by deploying 802.11n Draft 2.0. In this case, the benefit is derived by devices using older 802.11b/g technology. The multiple input, multiple output (MIMO) technology in 802.11n Draft 2.0 has improved the call quality of the company's Cisco wireless IP phones by increasing network reliability and coverage predictability.
• A large U.S. hospital is deploying 802.11n Draft 2.0 to help ensure consistent connectivity for synchronous patient care applications deployed to mobile computer carts. Without 802.11n Draft 2.0, mobile carts were losing connectivity due to coverage holes caused by interference and multipath effects.
• Duke University and Western Michigan University are deploying 802.11n Draft 2.0 across campus to support a growing diversity of client devices and high-bandwidth applications.
The Time to Adopt 802.11n Is Now
Technology shifts are gradual events that generally take years. Now that 802.11n Draft 2.0 has become a de facto industry standard and the market is adopting 802.11n Draft 2.0 products in advance of a final ratified standard, adoption timeframes should be determined purely on business need. Providing the performance required for the truly mobile experience, businesses can adopt 802.11n with confidence today.
