Wireless Capturing of Multi-User OFDMA Frames

The introduction of the OFDMA feature in the 802.11ax standard gives us packet analyzers some challenges regarding wireless capturing. It is two aspects that are challenging. Capture data inside specific resource units (RUs) and how to visualize it in a graphic user interface (GUI) if we can capture several parallel transmissions.
Some experts have said it would be very difficult to do multi-user capturing, but I have always thought it should be possible to do this
It is basically the same transmission method as we have used for over 20 years. It is some new frame formats and the OFDM subcarriers are split between several stations, but that’s all (almost).

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UL OFDMA- Make RF Collisions Work

During 802.11ax UL OFDMA magic happens in the RF space. What were RF collisions before is with 802.11ax normal behavior.

I will in this blog briefly explain what happens in the RF space during UL OFDMA.
I recommend reading one of the previous articles where I explain what it looks like in Wireshark.
I will simplify it so it is two clients that will send their data uplink in two different 106-tones RU

A short summary of the UL OFDMA process
– The AP sends a Basic Trigger frame, as a broadcast frame, in the legacy frame format at one of the mandatory rates
– STAs (clients) that are announced in the Basic Trigger frame sends their data uplink to the AP in parallel
— The AP sends a broadcast Multi-STA BlockAck frame to acknowledgment the received data frames

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