July/August 2018 87
These are 1024QAM modulation that will help deliver
speeds up to 7 GB/s for a single user and multi-user MIMO
that uses beamforming to target specific users. MU-MIMO
is expected to boost data rates on crowded networks by a
factor up to four. Table 1 summarizes the three main Wi-Fi
Routers are also available. Examples are those from
D-Link such as the AX6000 and AX11000 that work in the
5 GHz band. Under the right conditions, they can produce
link speeds of 6 Gb/s or 11 Gb/s, respectively, using 4x4
Figure 2 shows a front-end module (FEM) from
Ethertronics that operates in the 5 GHz band. It includes
Ethertronics active antenna steering technology along with
a + 18. 5 dBm power amplifier that works with both 11ac
and 11ax in 80 and 160 MHz channels.
Don’t forget! To receive the benefits of any of these
newer standards like 11ac and ax, you must have the same
technologies on both ends of the link. To get full 11ac
benefits, the router or AP must meet the standard as well
as your laptop, iPad, or smartphone. Most of the newer
phones and laptops incorporate 11ac. However, it will be a
while before you see a critical mass of 11ax.
Always go for the latest standard but relax knowing
that all these devices are backward-compatible to retain
interoperability with older 11n and even 11g in some
Perhaps the biggest issue is the growing potential for
interference. Wi-Fi does use the unlicensed 2. 4 GHz and
5 GHz bands that are loaded with lots of other radios.
The 2. 4 GHz band is already shared with Bluetooth,
ZigBee, 802.15.4 ISM band radios, and cordless phones.
Furthermore, the allocated Wi-Fi bands are limited so there
is some contention for the channels that occurs in areas
where multiple Wi-Fi access points are closely adjacent.
On top of that, the growing adoption of the Internet
of Things (Io T) using Wi-Fi will potentially put thousands --
even millions -- of more devices in the same spectrum that
will surely lead to even more interference.
Another issue that has risen over the years is more
users per access point. Each AP can handle multiple
connections at a time, but it slows the data rate for each.
The newer standards have addressed this capacity problem
by using MIMO and boosting speed.
Another forthcoming problem is running out of
spectrum. Wi-Fi has only been allotted a certain amount
of space in the 2. 4 and 5 GHz bands. With the new 11ac
and 11ax standards using ever wider channels (up to
160 MHz), the spectrum is used up quickly and capacity
limited. More spectrum is needed if the quest for ever
higher speeds continues.
One possibility is the 3. 5 GHz band that may offer
some additional space. More of the 5 GHz band would
be ideal, but many others are seeking space in that band
as well. No one seems to know now where the extra
spectrum will be or when.
In case you didn’t know, the cellular carriers are all
using a part of the Wi-Fi 5 GHz spectrum for offloading
some high speed data streams. Two technologies are used:
one is called LTE Licensed Assisted Access (LAA), and
LTE-U for unlicensed. When the cellular network is at its
Table 1. Summary of the Most Recent Wi-Fi Standards
Figure 2. The Ethertronics EC714 front-end module
(FEM) operates in the 5 GHz band and is designed to be
incorporated into 11ax and 11ac equipment.
IEEE Std. Ratification Date Band Technology Modulation Channel BW MIMO Max. Speed
802.11n 2009 2. 4 & 5 GHz OFDM Up to 64QAM 20, 40 MHz Up to 4x4 600 Mb/s
802.11ac 2013 5 GHz OFDM Up to 256QAM 40, 80, 160 MHz Up to 8x8 3 Gb/s+
802.11ax 2019 expected 2. 4 & 5 GHz OFDM Up to 1024QAM 40, 80, 160 MHz 8x8 MU- MIMO Up to 7 Gb/s