I read several papers about CSI data, but one thing is not clear. I would like to extract csi from legacy rate packets. I read some forums related to existing CSI tools and they only state that CSI can be obtained only from HT rate packets (atheros csi tool and Intel linux csi tool). They do not mention why we cannot obtain CSI from legacy rate packets (for example a probe request - usually 802.11b).
This page clearly describes the HT and non-HT packet structures: https://www.mathworks.com/help/wlan/ug/wlan-packet-structure.html
There I noticed the "so special preamble" which belongs to the HT packets. And I am rougly aware of different modulation types used for different rates.
So finally my questions are:
- In theory is that possible to obtain CSI from b/g rate packets with basic or special wifi adapters with multiple antennas (using it as AP or client or in monitor mode)?
- If so, how should I modify either the Intel CSI tool or the Atheros csi tool to make them suitable for CSI extraction?
I hoppe in that it is possible but not implemented neither by the Intel csi tool neither Atheros.
Any help is appreciated.