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xieyaxiongfly / Atheros_CSI_tool_OpenWRT_src

GNU General Public License v2.0
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Getting 56 subcarriers in 40 MHz #25

Closed itskalvik closed 5 years ago

itskalvik commented 5 years ago

Hi, I have a WDR4300 setup at 5GHz 40 MHz and a desktop client connected to the router. I used wavemon to verify that the connection is indeed at 40MHz but the recv_csi tool is giving me only 56 sub carriers. I tried using another WDR4300 router as the client at 40MHz and still got 56 sub carriers, I also setup a desktop as the AP at 5GHz 40MHz with hostapd and used another desktop as the client and got only 56 sub carriers. I have the AR9380 NIC on the desktops. Did anyone manage to get all 114 sub carriers?

djydo commented 5 years ago

Hi @kdkalvik,

Yes, it is possible to get CSI on 114 subcarriers at 5 GHz. Set AP (4300 router) to 40 MHz using luci or OpenWrt GUI before associating the client to the AP. The AP is running OpenWrt version of atherosCSI and client is using ubuntu 4.1+ kernel.

itskalvik commented 5 years ago

I tried that but for some reason I keep getting only 56 sub carriers. Got any suggestions?

djydo commented 5 years ago

I experienced the same thing on 2.4 GHz but not on 5 GHz. The transmission could not use 40 MHz even after I set bandwidth to 40 MHz using wireless utility, luci or GUI. So, I assumed it was an issue with my wifi card (iface0).

Were you able to verify that the AP was using 40 MHz on 5 GHz? Try to confirm that on the wireless overview for associated stations.

itskalvik commented 5 years ago

Yeah, I used the web interface to check 40MHz and it was indeed using 40MHz. Even when I used desktops on both AP and client, I was able to verify that I have 40MHz with wavemon. Not sure what the issue is.

djydo commented 5 years ago

check openwrt forum maybe some of the info can help.

itskalvik commented 5 years ago

Figured it out, I was setting the MCS rate to 16 on the transmitter by updating the rate_index_table by echoing 18 into it. But it is supposed to be 78, to set it to MCS 16 at 40MHz.