Steer clear of 'pre-certified' 802.11n kit, warns analyst

Network managers should avoid buying pre-certified 802.11n products because of the poor performance of wireless devices that use the protocol, analyst firm Burton Group has warned.

Network managers should avoid buying pre-certified 802.11n products because of the poor performance of wireless devices that use the protocol, analyst firm Burton Group has warned.

Standards body the Institute of Electrical and Electronics Engineers has been working on a faster version of 802.11 for several years. The new standard, 802.11n, is designed to turn a weakness of wireless technology, known as multipath interference, into a strength by using Mimo (multiple input, multiple output) technology.

Mimo uses multiple antennas and transmits information over mul­tiple paths simultaneously, thereby boosting effective throughput to hundreds of megabits per second, depending on the antenna configuration.

Paul DeBeasi, senior analyst at Burton Group, said in a recent paper that the 802.11n standard had been undergoing intense scrutiny, and a group of leading wireless Lan suppliers had formed the Enhanced Wireless Consortium (EWC) to try to break the deadlock in the IEEE 802.11n committee.

"They were ultimately successful, and a single draft document - draft one - was formed as the basis for the new standard," said DeBeasi.

Many suppliers are aggressively promoting pre-standard 802.11n products, but DeBeasi urged network managers to avoid purchasing pre-standard 802.11n products.

"Many suppliers now sell 'pre-n' products based on an early draft of the 802.11n standard. Early tests show that these products do not provide supplier interoperability, and can negatively affect existing 802.11g networks," he warned.

Other problems highlighted by DeBeasi include pre-n products exhibiting mediocre throughput results and offering a signal range that is worse than 802.11g.

There is also no cross-supplier compatibility and pre-n products will require hardware upgrades to support the final 802.11n standard.

More information

www.ieee802.org

www.enhancedwirelessconsortium.org

What does the draft 802.11n specify?


802.11n is a draft specification for a faster Wi-Fi protocol with a theoretical bandwidth of 540mbps. It uses Mimo (multiple input, multiple output) to enable the deployment of multiple transmitter and receiver antennas to increase data throughput, through a technique known as spatial multiplexing.

In May 2006, draft 1.0 failed to pass the first ballot and received more than 12,000 comments, although many of these were minor in nature.

The eventual standard will operate in the 2.4GHz (802.11b/g) and 5GHz (802.11a) frequency bands. The standard will be backward-compatible with 802.11b/g/a and will specify use of Mimo technology. It is likely that multiple Mimo antenna configurations will be allowed and that suppliers will offer products at several price/performance points.

The IEEE expects the 802.11n standard to achieve final working group approval by January 2008.

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