By David John Urban, Comcast
Wi-Fi 6 based upon 802.11ax standard changes the OFDM carrier spacing and the multiple access method for the first time in 16 years.
The subcarrier spacing is narrowed by one fourth resulting in symbol times four times longer allowing the spectrum to be divided into many resource units to be shared by multiple users at the same time.
A home may have several video set top boxes and security cameras and each member of the family may actively be using a phone and notebook computer with messaging and video streaming applications.
Thus, twenty active stations consuming less than 5 Mbps each is an important use case.
The devices can be served efficiently with OFDMA.
Each device transmits and receives a narrow portion of the 160 MHz channel width.
This is more robust for each station while still efficient since many stations are served at the same time.
In addition to many devices in the home consuming small average data rates, the cable operator is expected to deliver the Gbps service tier that the customer pays for.
Serving many stations simultaneously with OFDMA frees up air time for devices that occasionally demand much higher peak data rates.
Wi-Fi 6 PHY rates for 2x2 80 MHz phones and tablets will be 1200 Mbps, for 2x2 160 MHz notebooks will be 2400 Mbps, for 4x4 160 MHz desktop computers with media bridge adapters 4800 Mbps.
These PHY rates are critical for the stable, reliable, consistent delivery of Gbps service in the presence of spectrum sharing both within the home and with neighbors.
The phone with 1200 Mbps maximum PHY rate can be expected to deliver speeds of 700-900 Mbps in the same room and adjacent rooms as well as directly above and below.
The notebook with 2400 Mbps maximum PHY rate can be expected to deliver equivalent speeds of a 1Gbps Ethernet NIC with whole home coverage.
This paper describes the technical details of Wi-Fi 6 802.11ax high efficiency and why the technology is critical for cable operators to deliver consistent, stable, reliable Gbps service.