FAQ: 802.11n wireless networking

Computerworld - 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.

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 Corp., 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 Inc. 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.