drop off quite quickly. This is the same effect known to
photographers and astronomers as the Inverse Square Law,
where if a source of radio waves or light is broadcasting in all
directions, moving twice as far away leads to a drop in signal
strength of four times.
Wi-Fi 6 has some tricks up its sleeve to address this,
however. And many of them are also coming to our cities in
the form of the new 5G mobile phone network. “They’re
getting more similar,” says Nekovee of the two, previously
quite different, data transfer technologies. “They pick up stuff
from each other. One of the features of 5G is Massive MIMO
[multiple input, multiple output], so basically you have more
antennas on the base station,
up to 64 for 5G. Wi-Fi 6 has
eight antennas, and this can
do two things: It can support
more simultaneous users,
with beam-forming to beam
each data stream at a user; or
you can offer all the streams
to a single user.”
Then there’s OFDMA. Orthogonal Frequency-Division
Multiple Access allows you to split each Wi-Fi channel into
sub-channels. It was a feature of Wi-Fi 5 too, but while that
standard allowed 52 sub-carriers per 20MHz band, Wi-Fi 6
has 234. This allows it to efficiently parcel out the bandwidth
between multiple users, bringing back unused channels more
quickly so they can be reassigned.
BRING DOWN THE WALLS
But it’s a much older technology that can stand in the way of
Wi-Fi signals: Walls. The lower down the electromagnetic
spectrum you go, the more transparent walls are. Up at the
visible light end, they’re opaque, but Wi-Fi is operating far from
those frequencies, as Nekovee explains, “This is a
fundamental of physics. Generally, as you increase in
frequency, your wavelength shrinks. If you’re in the TV band
around 700MHz your wavelength is around 50cm, when you
move up to Wi-Fi it becomes a few centimetres, as you go
higher, to 5G where its wavelengths are measured in
millimeters, then we go all the way up to light, where you’re
measuring it in nanometres.”
Ah, yes, we can help here—we’ve noticed light doesn’t
penetrate walls well. “Yes,” says Nekovee, continuing, “So the
wavelength in the VHF [radio] band is a kilometer or
something, so it just doesn’t
see these obstacles. The
smaller you go, the more the
waves start to ‘see’ these
things, they can get trapped,
reflecting off multiple
surfaces so they cannot
penetrate. The other reason is
that as wavelengths get
smaller they begin to be absorbed by molecules.” This is why
for long-range radio communications very low frequencies are
preferred, and why 5G antennas tend to be placed closer
together than 4G ones might have been.
As Wi-Fi and 5G get closer together, it’s easy to imagine a
future where there is only one data transfer standard, and you
don’t have to worry about switching when you leave the
house. For now though, Wi-Fi 6 provides enough home
bandwidth for an enthusiastic digital family even if it doesn’t
touch the speeds and stability provided by a wired network.
Never fear, however—Wi-Fi 7 is already being discussed.
Ian EvendenFAR LEFT: Wi-Fi chips
are now so small they
can be installed in
tiny ‘internet of
things’ devices, as
well as the slimmest
of smartphones.LEFT: Professor
Nekovee is the head
of the Center for
Advanced
Communications,
Mobile Technology,
and IoT at the
University of Sussex.NETWORKING OVERVIEW What are the technologies that move data?
MESH TOGETHER
Some cell towers operate a bit like a
mesh network already, wirelessly
passing data between one another.PLUG AND PLAY
Homeplug can be combined with Wi-Fi
to create a mesh network that engulfs
your whole home in a cloud of internets.THE MODEM/ROUTER
Routers move data in and out using
antennas on the top and Ethernet
sockets on the back.“GENERALLY, AS YOU INCREASE
IN FREQUENCY, YOUR
WAVELENGTH SHRINKS”WIRES EVERYWHERE
A wired Ethernet connection is still your
best bet to get data quickly and safely
over long distances or through walls.Tech Report
HARDWARE