I have conducted tests using IPerf2.X over WiFi with a mobile phone and a laptop acting as an IPerf server connected to a router TP-Link AX5400. I have also utilised another laptop as a WiFi sniffer, capturing frames and packets in Wireshark.

During these tests, I have observed a peculiar phenomenon. When I measure throughput, the IPerf2 server displays a higher data rate than what is physically possible. The maximum physical data rates are derived from the captured Wireshark frames.

As an example, a measurement was conducted with a distance between the mobile phone and the router of 34 metres. The output of the Iperf server is as follows:

`C:Userslehre>iperf2 -s -i 1 -w 128M -p 5001
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size:  128 MByte
------------------------------------------------------------
[452] local 192.168.0.80 port 5001 connected with 192.168.0.46 port 51334
[ ID] Interval       Transfer     Bandwidth
[452]  0.0- 1.0 sec  5.31 MBytes  44.5 Mbits/sec
[452]  1.0- 2.0 sec  5.65 MBytes  47.4 Mbits/sec
[452]  2.0- 3.0 sec  4.80 MBytes  40.2 Mbits/sec
[452]  3.0- 4.0 sec  3.79 MBytes  31.8 Mbits/sec
[452]  4.0- 5.0 sec  3.85 MBytes  32.3 Mbits/sec
[452]  5.0- 6.0 sec  4.23 MBytes  35.4 Mbits/sec
[452]  6.0- 7.0 sec  5.28 MBytes  44.3 Mbits/sec
[452]  7.0- 8.0 sec  4.47 MBytes  37.5 Mbits/sec
[452]  8.0- 9.0 sec  5.16 MBytes  43.3 Mbits/sec
[452]  9.0-10.0 sec  5.41 MBytes  45.4 Mbits/sec
[452]  0.0-10.7 sec  51.4 MBytes  40.4 Mbits/sec`

The iperf command used on the mobile phone is as follows:

`iperf -c "ip-address" -p 5001 -i 1 `

And if i look at the first Data Packets i see that

Wireshark capture of distance throughput measurements

Upon closer examination of the radiotap header, the following information was obtained:
MCS Modulation: 0x1, Guard Interval: 0.8us, 2 Spatial Streams

Radio tap header of captured frame

Accordingly, the maximum data throughput from the aforementioned information is 34.4 Mbits/sec.
MCS Index Data Rates

Data Rates

As illustrated, the throughput achieved is 44.5 Mbits/sec, which is above the physical limit of 34.4 Mbits/sec.

Is there any additional information that I should be aware of in order to explain this phenomenon? Or is there something that I am doing incorrectly?
I would have expected a lower throughput than the maximum physical data rate due to management frames. However, this is not the case.

Should you require the Wireshark capture, I can upload it upon request.