802.11n uses multiple input / multiple output (MIMO) technology and a wider radio frequency channel. It also provides a mechanism called frame aggregation to decrease time between transmissions. Current WLAN technologies require that the sending station request the channel, send one packet, release the channel, and then request again in order to send the next packet. With frame aggregation, once a station requests the channel and has the authority to transmit, it can transmit a series of frames without having to release the channel and regain authority for each frame. With 802.11n, raw data throughput is expected to reach as much as 600 Mbps -- that's more than 10 times the throughput of 802.11g.

Although the IEEE began work on 802.11n in 2004, progress in ratifying the specification has been stalled by competing vendor groups. Draft 1 of the standard was released in 2006 and "pre-N" equipment became available shortly after. Draft 2 was approved in 2007. Pre-N equipment has demonstrated a data rate as high as 540 Mbps with typical rates between 100 and 200 Mbps. Data rates are expected to increase as experience with the standard grows.

The final 802.11n standard is not expected to be released until sometime in 2010, but any changes between Draft 2.0 and the final ratified standard are expected to be minor. In the meantime, the WiFi Alliance has been testing pre-N equipment for interoperability and adherence to Draft 2.

See also: single stream 802.11n

Learn more

This E-Guide explains what to expect with 802.11n, when to expect it and what you need to consider when deploying 802.11n.

Lisa Phifer explains how 802.11n antennas work in Understanding 802.11n wireless antennas.

To learn more about the 802.11 family, see our 802.11 Fast Reference
>> Find white papers, products and vendors related to 802.11n.

Read more about it:
>>	Wifi Net News provides news on the latest developments in the 802.11 standards.
>>	Progress of the 802.11n task group is tracked at the IEEE Web site.

Last updated on: Apr 06, 2009