mobisys2018_nexmon_channel_state_information_extractor
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seemoo-lab
How could we know the valid bandwidth in channel state information data?
Hi, I found that this tool will always collect 256 complex numbers per frame for 80MHz bandwidth, even when the transmitter is sending packets on 20MHz/40MHz bandwidth. Thus only some of the 256 complex numbers are valid. My questions are how to know which part of the 256 complex numbers is valid and how to know the bandwidth of the transmitter.
It would be best to check the bandwidth of the received frame in the ucode and only copy the values that are required. Alternatively, you can check the bandwidth somewhere in the d11rxhdr that prepends every received frame. https://github.com/seemoo-lab/mobisys2018_nexmon_channel_state_information_extractor/blob/master/src/csi_extraction.c#L96
In the end, you can also check which subcarriers of the csi have values close to zero or even zero and only consider the block that differs from zero.
On Wed, Apr 25, 2018 at 9:42 AM, Bingxian Lu [email protected] wrote:
Hi, I found that this tool will always collect 256 complex numbers per frame for 80MHz bandwidth, even when the transmitter is sending packets on 20MHz/40MHz bandwidth. Thus only some of the 256 complex numbers are valid. My questions are how to know which part of the 256 complex numbers is valid and how to know the bandwidth of the transmitter.
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-- Matthias Schulz Secure Mobile Networking Lab - SEEMOO
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