802.11AX

802.11ax is adopting many of the advantages of cellular LTE which has been very  successful in urban areas using frequency division multiplexing. By using smaller channels its enables more aggregate performance.

Work on 802.11ax took over 4 years to develop due to the complexities of radio design and digital signal analysis.

802.11ax will be anywhere from 4x to 10x faster than existing 802.11ac, but the wider and multiple channels greatly increase throughput. Speed is increased by 4x using wider 160 MHz channel. The equivalent 802.11ac connection will be only 866 Mbps.

Using a 4×4 MIMO access point , 802.11ax can aggregate 14 gigabits per second. A 802.11ax client can reach gigabit speeds with 2 or 3 channels.  In the most crowded areas using 40MHz channels, 802.11ax can deliver 800 megabits per second.

Mobile machines will benefit from 802.11ax as it uses less power by switching the Wi-Fi off and on using millisecond timing.

2.4 GHZ

2.4 ghz wi-fi spectrum

Originally with 802.11b and 802.11g the 14 channels at 2.4 GHz were adequate for the lower bandwidth speeds. The spectrum analyser shows how with 802.11n and 802.11ac the whole spectrum is overwhelmed. Now channels 1, 6 and 11 are all that can be used with 20 MHz channel width.

With 802.11n and 802.11ac there are only 3 practical channels available. The image shows how some users are setup with channel 3 which overlaps and interferes with channel 1 and channel 6. The users on channel 9 overlap channel 6 and cause interference.  The user on on channel 10 interferes with the users on channel 11.

5 GHZ

5 ghz wi-fi spectrum

The 5-GHz band is actually four frequency bands: 5.1-GHz, 5.3-GHz, 5.4-GHz, and 5.8-GHz. The 5-GHz band has a total of 24 channels with 20 MHz bandwidth available. The span for 20 MHz channels is vast which is why we strongly recommend abandoning 2.4 Ghz completely. 802.11a, 802.11n and above all support 5 Ghz.

The 802.11n standard calls for automatic channel selection which is why the image shows very little overlap.  The idea is to use a mesh network so that access points cooperate to eliminate interference as much as possible. Most overlap is caused by very distant access points that may not be able to interact.

Now 802.11ac does allow for wider 40MHz and 80MHz channels which clearly would start overwhelm even the 5 Ghz band. The largest 160GHz channels are not very useful in dense population areas.

wireless-ap-air-cap3702i-h-k9MU-MIMO

Each channel may not be fully utilized so by carving it up  over time, several uses can share it more effectively.

MU-MIMO carves each channel into as many as 32 thin temporal slices. These are then stacked so that over 4-8 channels so a small part of the bandwidth may come across different time slices within a given channel. The the various packets are reassembled at the client.

This makes sense when a busy area like a stadium has some 50,000 fans with mobile phones all sharing pictures and tweets. The swarm of mobile devices is hard to imagine.

The Cisco 3700 series 802.11ac 4T4R access points are up to the task. Combined with suitable routers behind them, the Cisco hardware is the most robust solution available.

802.11ax expands on the MU-MIMO. Given that the RF spectrum is limited, it makes sense to use every available slice efficiently.

For mobile phones, 1T1R is typical. Laptop and desktop machines can have 2T2R hardware. Each platform has differing RF utilization that makes it MU-MIMO very important.