Increased Streaming Content & New Devices Drive the Need for Wi-Fi 6
Streaming video over the Internet accounts for 82% of all Internet traffic. The 2020s will bring widespread use of IOT devices in every home and enterprise and more personal devices. Additionally, 8k video will become commonplace and streaming media bitrates will rise again.
The 802.11 Standard – the foundation of Wi-Fi 6
The 802.11ac standard introduced in 2013 builds on several successful technologies from 802.11n. 802.11ac allows wider channel bonding up to a practical limit of 80 MHz, airtime fairness and standardized beam-forming. Also, 802.11ac wave 2 technology introduced multi-user MIMO (DL MU-MIMO) capability to help bridge the gap between the access point capability and the client device capability. Access points are physically larger, support more antennas, are plugged into the AC mains for continuous power, and include high-performance CPUs and DRAM. Client devices are designed for great cameras and screens but do not have the CPU processing power to use multiple streams and do not have space for optimal antenna design. Thus, MU-MIMO allows the access point to transmit concurrently to more than one client at a time. In 802.11ac, MU-MIMO is limited to downstream packet only, thus it is often written as DL MU-MIMO.
Whereas 802.11ac made the network faster, 802.11ax is designed for higher channel efficiency in a dense networking environment. The key technology behind 802.11ax, multiple access OFDMA, comes from the 3GPP LTE cellular technology and 802.16e WiMax. OFDMA, orthogonal frequency division multiple access, is a field-proven technology to support higher density wireless networks. 802.11ax anticipates higher density in several ways; scheduled transmission time, dynamic frequency allocation in 2 MHz increments, spatial reuse and improved battery management mechanisms.
OFDMA divides up the 20 MHz channel into 256 subcarriers. The smallest unit is 26 subcarriers in 2 Mhz of frequency. These subcarriers can be grouped together into larger units; at 52 (4 Mhz), 106 (8 Mhz), and 242 (20 Mhz) to support higher bandwidth applications. Each grouping of subcarriers are called a resource unit (RU).
Any single client device is assigned one or more RU. Each RU can be transmitted at a unique QAM level. Additionally, as the client device moves farther away from the access point, the number of RU and the QAM level can be adjusted to maintain a strong signal level even as throughput degrades.
As the 802.11ax technology evolves, MU-MIMO will work in both downstream and upstream directions. Another key advantage with 802.11ax is support for eight concurrent MU-MIMO transmissions concurrently, double the number supported by 802.11ac. One of the limiting factors for MU-MIMO in 802.11ac is the high management overhead required to communicate subcarrier information to the access point. In 802.11ax, enhancements to MU-MIMO will include grouping multiple client updates together to improve protocol efficiency and remove excess management overhead. The capacity and high throughput advantages make MU-MIMO another key technology for 802.11ax.
When to Upgrade the Network to Wi-Fi 6
When deciding when to consider a network upgrade, network operators need to calculate the cost/benefit of upgrading to 802.11ax. The new Wi-Fi 6 access points improve performance and efficiency beyond 802.11ac networks even without the use of 802.11ax devices. By upgrading now, businesses can deliver more simultaneous video streams, and support more concurrent users and devices than before.
The standard will be ratified in late 2020, and factors include the availability of equipment and support and the population of Wi-Fi 6 devices. Other factors include:
- Client and ecosystem support including standards ratification and interoperability support
- Density growth trends
- Backward compatibility with legacy devices and systems
- Available RF spectrum within a crowded RF neighborhood
- State of IoT applications if applicable
- Equipment cost