What's what in wireless proposals
Round-up of all Wi-Fi specs
By Joanie Wexler | Network World US | Published: 15:28, 29 July 2009
The seven-years-in-coming 802.11n standard is reportedly headed toward ratification in mid-September. 802.11n's specification suite is up to Draft 11, and will probably leave off there. Today's products are compliant with Draft 2.0 specs, though industry suppliers have long insisted that their 2.0-based 802.11n products, many shipping since 2007, will be interoperable with the final standard.
And the Wi-Fi Alliance, which tests and certifies 802.11-based products for interoperability with one another, has said it will not change its current Draft 2.0 802.11n certification programme in light of 11n ratification, other than to add testing in late September for some optional features in the final standard.
Among those 802.11n options are the following:
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- Packet aggregation, which makes data transfers more efficient.
- Space-time Block Coding (STBC), a technique that allows clients with only one antenna (and thus only one spatial channel), such as wireless phones, to leverage multiple antennas on an 802.11n access point to improve performance and range.
- Channel coexistence measures for "good neighbor" behavior when using 40MHz operation.
- Testing for devices supporting three spatial streams. Products on the market today support two spatial streams. As many as four are allowed by the standard.
About 600 Draft N 802.11n products have been Wi-Fi Certified since June 2007, when products based on the Draft 2.0 specification became commercially available.
Meantime, what about other 802.11 standards for meshing, management and so forth? According to the IEEE's 802.11project status website, here are some updates on standards you might or might not know are in progress. These are their predicted ratification dates as of July 22, 2009:
- 802.11p (Wireless Access for Vehicular Environments): November 2010
- 802.11s (Mesh Networking): January 2011
- 802.11u (Interworking with External Networks): September 2010
- 802.11v (Wireless Network Management): June 2010
- 802.11aa (Video Transport Streams): October 2011
- 802.11ac (Very High Throughput at <6GHz): December 2012
- 802.11ad (Very High Throughput at 60GHz): December 2012
A Wi-Fi Alliance spokesman notes that 802.11ac and 802.11ad might get new monikers, such as "802.11n Very High Throughput" or something of that sort.