Once upon a time, connectivity was simple. Devices, from photocopiers to fax machines, were connected by metal wires in walls or floorplates. Even well into the Internet era, the trusty RJ-45 was all any technician needed to deal with.
Then, the wires came off.
Mobile phones freed us from wall sockets. Bluetooth connected nearby devices into mini-webs. Analogue turned to digital, as 1G through 5G evolved. While Wi-Fi and cellular networks made wireless the norm in hot-desking offices, shopping malls, sports stadiums, and beyond.
You already know they’re not all the same technology. Perhaps you also know they use different sections of the electromagnetic spectrum, at different power levels. But you may not know all their use cases – and how some are better suited to certain applications than others. And, most importantly for your business, to know how they can work together.
In this article, part of our Our Wireless World series, we’ll set our sights on these two: cellular (“LTE/5G”) networks, and Wi-Fi. For each, we’ll define what they are and how they work, accompanied by notes on typical use cases, and finally illustrate come together as a team. Let’s get started.
Explaining Wi-Fi
Wi-Fi is a trademark for the 802.11x set of standards from the engineering body of the IEEE. Like most technical standards, it’s designed so any company can produce Wi-Fi gear: as long as your product meets the standard, it should operate with any other piece of Wi-Fi equipment. Wi-Fi provides services in private homes, businesses, as well as in public spaces.
Like all equipment that uses radio waves (including cellular networks) the quality of a Wi-Fi signal depends on how far you are from its source. Practically, that maxes out Wi-Fi at around 100m. The reason for this is the frequency of that signal. Wi-Fi uses two “bands” of the spectrum, 2.4GHz and 5GHz – fairly high frequencies.
This matters, because one basic rule of wireless is that the higher the frequency, the higher bandwidth your users can enjoy. Traditional FM radio, even on the VHF frequencies, uses much lower frequencies, just 108MHz and below. (Which is why you don’t buy your broadband from your local radio station.)
There’s a caveat, though:
the higher the frequency, the shorter the distance it’ll push through a medium like air, walls, or rainy weather. This is why the use case for Wi-Fi looks best indoors and at close range. But within that limitation, Wi-Fi is surprisingly flexible: the right mix of routers and boosters can cover an office floor, a mixed-use building, or even multiple neighbouring buildings. (Nevertheless, it's common that while moving from router to router, your signal drops. It might only be a few seconds, but you'll notice it while walking with your laptop, trying to maintain a conversation during a Teams call).
Cellular networks: it’s about more than phones
Cellular networks, of course, connect your mobile phone to the world, with cell towers swapping your connection between them as you move around. Early 1G mobile phone networks were much lower-frequency than Wi-Fi, at below a gigahertz. But modern 5G/LTE networks are on a par with Wi-Fi, at 3.3-3.8GHz, meaning high-speed potential of up to 20Gbps in perfect conditions.
Note, however, the two systems have different technological underlays. (“5GHz Wi-Fi” has nothing to do with “5G” mobile networks!) Whereas Wi-Fi was designed as an open data standard, spraying packets of bits to laptops and desktops in a home or office, its signal strength is (deliberately) weak – using an unlicensed part of the spectrum, it’s all too easy for adjacent Wi-Fi equipment to interfere with each other. 4G/5G evolved from mobile telephony and is “licensed” – MNO’s have paid a fee for exclusive use of a chunk of spectrum, usually paid to national governments.
Enabling mobility
And while you can’t move seamlessly between Wi-Fi networks without a bit of work, cellular networks would switch your connection between towers without you noticing, perhaps hundreds of times on a busy day (if you are on the move). This also means plenty of mobile device users can occupy a small area without the network falling down: in some cities, you’ll see cell towers just a few tens of metres apart, allowing hundreds of simultaneous connections in each cell’s coverage area.
But here's where physics looms large again. Operating on similar frequencies to Wi-Fi, 5G suffers the same range limitations. So, a cellular network offering 5G must place its cell towers much closer together than a pure-play 3G or 4G running on lower frequencies.
Learning this, you might wonder why we need 5G at all. Doesn’t Wi-Fi offer much the same potential?
Well, there’s a huge advantage: unless you’re the proud owner of one of the 150+ private (and very pricey) cellular networks around the world, public LTE/5G covers much of the planet’s populated area already. Ready for you to make use of … with a simple data subscription.
And that’s where Wi-Fi and cellular can come together – at a very effective cost.
