FAQ: 802.11n wireless networking

Editor’s Note: This story is reprinted from Computerworld. For more Mac coverage, visit Computerworld’s Macintosh Knowledge Center.

Wireless networking using the 802.11 standard, also known by its trade name, Wi-Fi, has become common in the home and has a significant and growing role in corporate settings. But the existing standard, 802.11g, was ratified in 2003 and is increasingly seen as inadequate as applications become more complex and require more bandwidth.

For instance, streaming video — whether it’s a feature-length movie at home or videoconferencing at work — is a dicey proposition with 802.11g. So-called “g” products have a theoretical maximum throughput speed of 54Mbit/sec. but real-world speeds of half that or even slower, which isn’t quite enough for video.

To the rescue, eventually, will be 802.11n, which promises significantly higher speed and range. Here’s the lowdown of what to expect with 802.11n and when to expect it.

Already, Apple is shipping 802.11n-based devices. Its new AirPort Extreme Base Station supports a draft specification of 802.11n, and the capability has been exposed in several of its Mac models.

How is 802.11n different than current generations of Wi-Fi?

The 802.11n standard uses some new technology and tweaks existing technologies to give Wi-Fi more speed and range. The most notable new technology is called multiple input, multiple output (MIMO). MIMO uses several antennas to move multiple data streams from one place to another. Instead of sending and receiving a single stream of data, MIMO can simultaneously transmit three streams of data and receive two. This allows more data to be transmitted in the same period of time. This technique can also increase range, or the distance over which data can be transmitted.

A second technology being incorporated into 802.11n is channel bonding, which can use two separate nonoverlapping channels at the same time to transmit data. This technique also increases the amount of data that can be transmitted. A third technology in 802.11n is called payload optimization or packet aggregation, which, in simple terms, means more data can be stuffed into each transmitted packet.

So, what are the benefits of 802.11n?

Users will notice two things about this new and improved wireless technology: significantly greater speed and range. Both Intel, which has a vested interested in 802.11n because it manufactures wireless chip sets, and independent reviews indicate that the claims of greater speed and range for 802.11n are true.

Specifically, 802.11g products, which have a theoretical maximum throughput speed of 54Mbit/sec., typically provide real-world speeds of 22Mbit/sec. to 24Mbit/sec. In contrast, Intel says it’s seeing real-world speeds of 100Mbit/sec. to 140Mbit/sec. for 802.11n equipment. Those results were confirmed in a recent Computerworld roundup review of several Wi-Fi products based on Draft 2 of the 802.11n standard.

Range is harder to quantify because it’s affected by many variables, such as barriers that could block the signal. However, Intel reports that 802.11n equipment typically delivers more than twice the range of 802.11g equipment, at any given throughput speed. Those results were confirmed anecdotally in the recent Computerworld review.

“At the very end of an open field with no interference, where you could get 1Mbit/sec. with “g” equipment, you’ll net 14Mbit/sec. to 16Mbit/sec. with “n” equipment,” reports Ashish Gupta, an Intel product manager.

What’s in it for business users?

Consumers are increasingly buying equipment based on draft versions of 802.11n. However, few businesses will deploy 802.11n products until the standard is fully ratified and business-focused vendors such as Cisco Systems offer products based on the ratified standard. When that happens, however, the role of wireless networking is expected to significantly increase in corporate settings.

Wireless networking in many companies often fills specific niches, such as providing networking in conference rooms, lunch rooms or in temporary or under-construction office space. That lack of full deployment of wireless is understandable given that Ethernet provides greater reliability and speeds (theoretical maximums of 100Mbit/sec.) and is switched, while wireless LANs offer slower speeds and the bandwidth is shared. The new 802.11n technology will solve the throughput problem for business users, opening the way to far more applications, such as wireless voice over IP and more videoconferencing.

And what about consumers?

The increased range of 802.11n will mean fewer “dead spots” in homes served by a single Wi-Fi router. It also will open the way to high-bandwidth applications such as streaming video from, say, desktop computers that store video to Wi-Fi-enabled televisions. The new standard will also be more reliable for voice-over-IP and, in general, for multiple users doing multiple things over the network.

Does the new standard have new security capabilities?

No. While Wi-Fi once was considered quite insecure, most current-generation products now support Wi-Fi Protected Access (WPA) and WPA 2 for encryption and authentication, which provide strong protection for wireless networks.

However, the Wi-Fi Alliance, the trade organization for Wi-Fi vendors, is instituting a specification aimed at making security easier to deploy by home users. The program, called Wi-Fi Protected Setup, enables setup of WPA or WPA 2 simply by pushing buttons or entering personal identification numbers. This program is not part of the 802.11n standard, but equipment vendors are starting to deploy it just as Draft 2 Wi-Fi products are becoming common.

Why is ratification of 802.11n taking so long?

The 802.11n standard is being developed by a working group of the IEEE. Under the best of circumstances, ratifying an important new standard is an excruciatingly slow, multiyear process, because working groups address the smallest nuances of the standards and discuss different approaches and then sort it all out and vote.

In this case, the ratification process started more than three years ago. Initially, there seemed to be agreement about one particular approach to meeting the goals of the standard, but a rift developed between vendors that slowed down the process even more than usual.

That rift has been resolved. At a March meeting in Orlando, the working group gave formal approval to Draft 2.0 and set as a goal to publish the final standard in October 2008 (Since then, the date for ratification has been pushed back to March 2009). The draft received more than 80 percent approval among voters in the group; 75 percent was required for approval. That indicates that there was a high level of consensus and that there likely will be few, if any, substantive changes between Draft 2 and the final, ratified version of the standard. However, a Draft 3.0 still must be approved, which will deal with Wi-Fi in consumer electronics devices such as camcorders and media players.

Does that mean we can’t expect 802.11n products until final ratification?

Products based on Draft 2 are available now and have received generally positive reviews both in terms of increased speed and range and compatibility with older Wi-Fi products. The products are being aimed at consumers; as stated previously, corporate IT shops are unlikely to be interested until after final ratification of the standard.

Vendors are not making promises, but they are saying it is their hope that the Draft 2 products will be firmware upgradable to the final, ratified standard when it is eventually approved. After that time, enterprise-focused vendors such as Cisco are expected to release 802.11n products.

Aren’t draft-802.11n products being certified by the Wi-Fi Alliance? If so, what does that mean?

The Wi-Fi Alliance is a trade organization made up of Wi-Fi vendors; it is not a standard-setting body. However, because the standard-setting process can be long and tortuous, Wi-Fi equipment vendors were anxious to release next-generation products. There were frequent reports that products based on Draft 1.0 had problems interoperating with older Wi-Fi products and with other Draft 1.0 products. However, products based on Draft 2 seem to be more reliable and interoperable.

To make sure that’s the case, the Wi-Fi Alliance will start certifying products based on Draft 2 this summer, testing for interoperability and compliance with the draft specification. That means that any products you buy that are certified will be backward compatible with 802.11a/b/g. It isn’t known yet, however, whether they will be forward compatible with products based on the ratified standard.

In addition, Intel is supporting Draft 2 802.11n technology in its Centrino chip sets. Vendors of equipment such as routers will be allowed to put a logo on their packaging indicating that those products work with the Intel gear.

David Haskin is a contributing editor specializing in mobile and wireless issues.

This story, "FAQ: 802.11n wireless networking" was originally published by PCWorld.

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