Asymmetric Rx Data rate vs Tx Data Rate

[edgar.bermejo@itesm.mx]

Hi everyone!

Does anybody had experienced asymmetric Data rate vs Tx Data Rate? Using WiFiTools in Windows PowerShell:

PS C:\WINDOWS\system32> monitor-wifistate

Date&Time	Stae	SSID	BSSID	Authentication	Receive rate (Mbps)	Transmit rate (Mbps)	Signal	Channel
17.02.2022-11:19:07>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	400	400	85%	56
17.02.2022-11:19:09>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	400	400	85%	56
17.02.2022-11:19:11>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:14>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:16>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:19>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:21>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:23>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:26>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	400	400	85%	56
17.02.2022-11:19:28>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	400	400	85%	56
17.02.2022-11:19:30>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:33>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:35>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:38>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:40>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:42>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:45>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:47>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:49>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	400	400	85%	56
17.02.2022-11:19:52>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	400	400	85%	56
17.02.2022-11:19:54>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	400	400	85%	56
17.02.2022-11:19:56>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:19:59>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:20:01>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	24	400	85%	56
17.02.2022-11:20:04>	connected	Tec	84:b8:02:47:d5:5e	WPA2-Enterprise	400	400	85%	56

Any thoughts why Rx Data Rate is changing while Tx Data Rate is not? Also, I know that is normal to have asymmetric Rx and Tx data rates but the difference is huge is this case. Any ideas?

The results were confirmed with an Ekahau site survey.

Just to be clear, I'm not talking about iperf tests (throughput) just plain data rates.

I'll appreciate any help. Thanks!

[Rich R]

Mismatched Tx power levels between client and AP?

That's assuming client driver and WLC software are both up to date.

[JPavonM]

It seems to me that the 24 Mbps packets are just management frames which are sent at the maximum basic data rate that is been agreed during association.

Additionally, marking different data rate for a single packet in both Tx and Rx at the same time? This seems to me that the guy who programmed this don't know that if the chipset is receiving, it cannot be sending, so one of the colums has no sense, and I think this is the Tx one.

In Wireshark OTAs, which packets do you see been transmitted at 24 Mbps?

[edgar.bermejo@itesm.mx]

Hi JPavonM,

Thanks for your answer. The script in PowerShell basically arranges in columns the data obtained from "netsh wlan show interface". As soon as possible will capture traffic.

Regards.

[Rich R]

Ah yes good point @JPavonM - I stand corrected

[JPavonM]

edgar.bermejo@itesm.mx can I ask you which wNIC and driver version are you using which suffer from such behaviour?