Secondly, you increase the speed available. The next generation of Wi-Fi, 802.11ac, uses wider channels than 11n [11n can combine two 20 MHz channels into a "fatter" 40-MHz channel; 11ac can combine 40 MHz channels into 80 MHz channels]. The table in my blogpost shows the higher capacity of the wider 80 and 160 MHz channels. With the existing spectrum, we don't have that many 80 MHz channels. That lack of wider channels will take the big speed increase off the table for 11ac users. But with the new spectrum [and added channels], 11ac networking just got the ability to carry much larger amounts of data.
How else does this affect Wi-Fi networking?
There's another interesting but a bit subtle effect. In Wi-Fi, the big factor is the signal-to-noise ratio [SNR], which has to do with how well you [meaning "a radio"] can "talk" above the ambient electrical noise in your area. As SNR improves, you can perceive finer differences in the signal, making it easier to talk above that background noise. The more SNR improves, the faster you can go.
And that has another related effect, dealing with the higher, 256 QAM modulation [introduced] in 11ac. To do 256 QAM, you have to pick out very fine distinctions. It's like throwing darts at a dart board that has more, but finer concentric circles: the more accurately you're able to throw, and the less air disturbance between you and your dart board, the better it is.
The No.1 cause of "noise" in Wi-Fi is other Wi-Fi devices: we "hear" each other transmitting. If you transmit, I can't. It's like being in a party that's in a small room, where you can hear this burble of noise from one or more groups talking around you. To be heard, you have to "talk over" that burble.
But with the new spectrum and more channels, it's like moving this party into a much larger room. When that happens, everyone is [in effect] spread out. So all the groups can talk more quietly, and you can recapture the subtlety in what you're talking about: you don't have to talk louder. And less interference means better speed.
So how will this change the Wi-Fi experience for end users?
Right now, these products exist only in laboratories. Imagine you have two 11ac products. One supports these new 5 GHz Wi-Fi channels and one doesn't. For the radio that doesn't, it will have a choice of 20 channels, which also will be sought by 11a and 11n clients. It will auto-select a data rate and it will not be able to use 256 QAM.
But the radio that can use the new channels will have a better signal-to-noise ratio. It can pick a different data rate, and make use of 256 QAM. It will be 25% faster. In a hospital with big medical images or a classroom with streaming video, these will all load faster.
Actually, the new channels will also help other Wi-Fi clients even if they can't use them.