IEEE 802.11ax will have a key role to play in boosting average throughput per user, offering four times higher efficiency, according to Alejandro Buritica, solutions marketer for wireless test at National Instruments. 802.11ax will offer PHY improvements, longer OFDM symbol time, and lower subcarrier spacing. Unfortunately, the lower subcarrier spacing can result in additional EVM effects, with nonlinearity, phase noise, and quadrature impairments all coming in to play. Consequently, the standard will require better EVM measurements and verification of multi-user operation.
The standard will require the receive and transmit measurements of 802.11ac. On the receive side, that includes minimum input sensitivity, adjacent channel rejection, nonadjacent channel rejection, receiver maximum input level, and clear-channel assessment (CCA) sensitivity. The transmit side will require spectral mask and spectral flatness tests as well as measurements of transmit center frequency and symbol clock frequency tolerance, transmit center frequency leakage, transmitter constellation error, modulation accuracy, and time of departure accuracy. In addition, Buritica said, 802.11ax requires an “unused tones error” test.
In a webcast scheduled for August 15 at 1 p.m. EDT, Buritica will elaborate on the R&D and manufacturing test challenges of 802.11ax—also known as High-Efficiency Wi-Fi (HEW)—with details on characterizing and validating an 8 x 8 MIMO system. You can register here.
