802.11n - the standard

January 17, 2008 //

Until a few weeks ago, I was under the impression that 80.11n standard is currently in draft when a friend of mine pointed out that his MacBook supports 802.11n. This got me thinking over 802.11n and how can a device be available for supporting a standard that is not finalized. Upon researching, I found out that many companies, including apple, have launched devices supporting the latest draft of the 802.11n standard and hope to provide firmware upgrades when the final standard rolls out.

 The 802.11n standard is an amazing improvement over the currently used 802.11g standard. 802.11n standard supports link rate of 600 Mbps in comparison to the current 54Mbps supported by the 802.11g standard. It also incorporates the MAC enhancements for QoS and power savings as defined in the 802.11e standard. The increase in the link speed can be attributed to the folowing enhancements:

1. Increase in subcarriers
The OFDM subcarriers were increased from 48 in 802.11 to 52 in 802.11n boosting the throughput.

2. Decrease in Guard Interval
The guard interval is decreased from 800ns to 400 ns

3. 40Mhz Channels
The other 802.11 standards have a channel bandwidth of 20 Mhz. 802.11n has an optional mode, where the channel bandwidth is increased to 40Mhz. As the channel bandwidth is doubled, the number of data subcarriers is slightly more than doubled, going from 52 to 108.


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  1. Anvay Lonkar said...

    Ankur, “Draft Implementations” are standard industry practises and many products are always developed before a final standard is released. These implementations not only help the company get first-to-market advantage but also aids the working committee gauge business as well as technical implications of the standard.
    Here is an article detailing various 802.11n routers : http://compnetworking.about.com/od/wirelessrouters/tp/80211nprenhome.htm
    and this one reviews the technology : http://www.eweek.com/c/a/Mobile-and-Wireless/First-80211n-Products-Show-Standards-Promise/
    Here is another article detailing on how such huge speeds are achieved in this standard : http://www.wirevolution.com/2007/09/07/how-does-80211n-get-to-600mbps/

    January 23rd, 2008

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