WLAN IEEE 802.11ax testing

The Wi-Fi 6 revolution

The IEEE 802.11ax PHY is essentially based on IEEE 802.11ac but uses a decreased subcarrier spacing of 78.125 kHz. This quadruples the symbol time, which, together with longer guard times, helps to improve robustness and efficiency. 1024QAM modulation and MU-MIMO will also be supported. The major changes come from the introduction of OFDMA, which enables multiple stations to be served simultaneously in order to improve overall capacity, latency and efficiency in dense signal environments. Resource units (RU) are being introduced to split the available spectrum in smaller parts. A scheduling procedure using trigger frames ensures synchronized uplink communications in OFDMA and MU-MIMO schemes.

Your 802.11ax test challenges

The 11ax standard defines various transmitter and receiver tests such as EVM, TX power, spectrum emissions and sensitivity. For example, 1024QAM modulation requires signal generation capabilities to transmit reference signals with very low distortion over a bandwidth of up to 160 MHz and the required analysis bandwidth. Completely new are tests to ensure that stations perform correctly in following the scheduling rules for time and frequency resources for the uplink, as defined in the new trigger frame. This includes measurements such as timing error, unused tone error and TX power adjustment, which requires a test solution in signaling mode.