Wi-Fi technology, as defined by the IEEC 802.11 standards, is continuing to evolve, and with each release becomes faster, stronger and more capable, as well as an increasingly viable option as a wireless sensor network (WSN) physical layer alternative. China has released IEC 62948:2017, a factory automation (WIA-FA) WSN based on Wi-Fi networks, so the option is available as an international standard with products available—at least on the Chinese market.
The accompanying table summarizes how the Wi-Fi standard has evolved over the past decade, adding more data capacity as well as improved data propagation capabilities to improve reliability and support for multiple users. The new features are interesting from an engineering perspective, but what matters is how it improves the wireless experience and, in our case, how it will help us run our facilities.
OFDMA allows a traditional 20 MHz channel to be partitioned into as many as nine smaller channels, meaning a Wi-Fi 6 AP could simultaneously transmit smaller frames, as would be the case for a low-bandwidth data transmission to nine Wi-Fi 6 clients. For an uplink, OFDMA allows data frames to be transmitted simultaneously by multiple stations, while in the opposite-direction downlink, OFDMA allows multiple data frames to be transmitted in a single data unit to multiple stations, in both cases amortizing preamble overhead and medium contention overhead, which leads to high aggregated network throughput. Downlink OFDMA can further optimize aggregate throughput by balancing the allocation of power between users at high versus low signal-to-noise ratios.
The new Multi-TID aggregated MAC protocol data unit (Multi-TID AMPDU) feature allows the aggregation of frames from multiple different traffic identifiers (TIDs) from the same or different quality of service (QoS) requirements within a single transmission; again, giving devices extra flexibility to aggregate more efficiently, reducing overhead and increasing throughput and overall network efficiency.
Wi-Fi 5 uses a maximum symbol constellation size of 256-QAM. With Wi-Fi 6 support for 1024-QAM, up to 10 bits of information can be sent during a given transmission, meaning over a short range, 1024-QA, it provides increases in throughput by 25% over a Wi-Fi 5 installation.
Operation mode indication (OMI) provides an efficient way for client devices to signal the maximum number of space-time streams and maximum bandwidth they will use to transmit and receive. Similarly, the BSS (basis service set) coloring technique is an enhancement of the black list/white list concept that means, rather than assuming whether or not a nearby signal on the same channel is likely to be a source of interference, a given transmitter can determine the likelihood of potential interference, thus improving spatial reuse by allowing the use of that adjacent channel if it is available.