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Are STBC mandatory for 802.11n?

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STBC for those who don't know are "Space Time Block Code" the feature of 802.11n that is supposed to extend the range to infinity and beyound. By using "an extra" antenna per transmission (typically, 2 antenna total for a MCS 0-7) your system will transmit the same data in two different version (Alamouti code, one example using two antenna will send this : http://upload.wikimedia.org/math/e/e/4/ee4bffb7ebd93995d80d85fd8b50677f.png horizontal is the antennas, vertical is time ).

Now the thing is while capturing traffic using Airpcap (802.11g version, I need to sell a kidney for the 802.11n version), I discovered this payload to one of my probe packet sent through a Intel wifi link 5100 AGN "draft N 2.0" certified.

You'll notice two "improvement" of 802.11n are unsupported on this card :
The Low Density Parity Check coding is unsupported, it's a drop in replacement for the g convolutional coding that can be used interchangeably in .n packet, supposed to be more error resilient, but is more computing intensive isn't supported.

And those .n STBC have been sent to the garbage too...

It seems the only "mandatory" and advertised functionality of this card is the support of supperior MCS and throughput (up to 15 with 40Mhz, the 300 Mbps one). However, the "resilience/longer range" enhancement brought by 11n have been quietly rendered optional.

Is the draft mandating the support of STBC and LDPC, or has it been sent to the optional can for STA ?

P.S. I forgot to add that LDPC also permit you to increase your bitrate. And STBC is one of the two mimo mode.
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