Radio Frequency Testing

802.11ax
1. What is 802.11ax
802.11ax (that is, Wi-Fi 6), also known as High-Efficiency Wireless - HEW, increases system capacity through a series of system features and various mechanisms, through better consistent coverage and reduced air interface media congestion. Improve the way Wi-Fi networks work so that users get the best experience; especially in dense user environments, provide consistent and reliable data throughput to more users, with the goal of increasing the average throughput of users by at least 4 times . In other words, Wi-Fi networks based on 802.11ax mean unprecedented high capacity and high efficiency.

2. 802.11ax technical composition
The most important changes in 802.11ax and how it compares to 802.11n and 802.11ac
802.11ax has new technologies such as MU-MIMO, OFDMA, multi-user uplink operation, 1024-QAM, and spatial multiplexing, which make it more obvious in high-density scenarios.

Main function one:
1. OFDMA technology
Not only increase user data rate, but also reduce latency, especially for a large number of devices with short frame or low data rate requirements, such as IoT devices. At the same time, it has a multi-user capability, which can combine data packets of various sizes from the perspective of modulation, the system overhead can be reduced through sharing, and it can support uplink and downlink at the same time, so the efficiency is improved. It is reported that both uplink and downlink OFDMA are mandatory requirements for WiFi Alliance 11ax certification. the
2. MU-MIMO technology
Utilizes multipath spatial channels to increase network capacity by allowing multiple devices to transmit simultaneously. 802.11ax improves on 802.11ac by increasing the downlink multi-user MIMO group size, allowing for more efficient operation.
3. Transmit beamforming
In existing functionality, the access point uses several transmit antennas to maximize the signal on the receiver antenna. It increases the data rate and extends the range. While 802.11ax APs can integrate up to 4 antennas (although the specs allow for more), 8-antenna 802.11ax APs are expected to be released in 2019.
4. High-order modulation
The highest modulation level of 802.11ax extends from 256-QAM to 1024-QAM. In good cases, this greatly increases data rates and leads to a better user experience. Compared with 802.11ac, the peak rate of 802.11ax is increased by 25%

Main function two:
1. OFDMA Creed
Orthogonal Frequency Division Multiplexing (OFDM) beliefs are the RF building blocks of 802.11, and for technical reasons, subcarrier spacing, symbol duration, and FFT size were all changed in 802.11ax to allow efficient operation of small OFDMA subchannels.
2. Outdoor operation
Many features of 802.11ax improve outdoor performance. On top of that is a new packet format where the most sensitive fields are repeated for robustness. Other features include longer guard intervals and a mode that introduces redundancy to allow error recovery.
3. Reduce power consumption
Existing power-saving mechanisms are complemented by new mechanisms that allow devices to sleep with longer intervals and scheduled wake-up times to reduce power consumption on client devices. Also, for IoT devices, only 20MHz channel mode supports simpler, lower power chips.
4. Compatibility
802.11a/b/g/n/ac.