Why your WiFi feels so slow sometimes

An XKCD comic strip is the perfect opportunity to talk about a key technology. Photo / 123RF

Randall Munroe, creator of the popular webcomic XKCD, is like the rest of us: He struggles with Internet reliability. In a new strip, Munroe explains how weird it is that to get faster downloads sometimes, he has to turn off his phone's WiFi connection and switch over to his cellphone carrier's mobile data instead.

For some, that might sound counterintuitive. After all, WiFi connects you to your home Internet - which you'd think would be plenty fast.

So, why does your WiFi get slow sometimes, anyway?

His strip offers a wonderful opportunity to talk about the details of a technology we all take for granted - WiFi - and what kinds of policies we could put in place to make things better.

It all boils down to the airwaves carrying information to your electronic device.

You can think of these airwaves as lanes on a highway. In many home WiFi routers today, you'll find two lanes. One whose waves operate at a frequency of 2.4 GHz and one that operates at 5 GHz. Data travels from the outside world into your home and through the router, at which point it's beamed wirelessly through the air and onto your device over these specific lanes.

There are a couple major things that can slow the lanes down, even if you're standing relatively close to your router. One is outside interference, and the other is congestion.

The first is pretty tightly controlled by regulators, who test wireless devices and impose restrictions to make sure that all wireless devices stay in the correct lane - whether that's WiFi routers, cellphones or satellites.

The second is more difficult, because billions of people are constantly switching on new wireless devices and demanding more access to the information highways.

Think about the typical American home, where over time, PCs were joined by laptops, then smartphones, then tablets, then smartwatches and wearable fitness trackers, then intelligent thermostats and on and on. Not long ago, many of these gadgets were a rarity; even today, there are only about 1.5 mobile devices for every American, according to the networking company Cisco. By 2020, that figure is going to double: For every American, there will be three mobile devices.

Many of these devices are, at one point or another, funneling data through WiFi connections. Last year, two-thirds of all information coming and going from mobile devices reached the Internet via WiFi. By 2020, it'll be 70 percent. Leading much of this future growth will be the proliferation of connected appliances and smart devices, otherwise known as the Internet of Things.

With all these wireless devices clogging the WiFi lanes, it's no wonder that things might feel a little sluggish.

Just like the highway for cars, one of the most obvious solutions for a congested WiFi highway is to widen it - or switch paths altogether, which is what you're doing when you turn off your WiFi connection and hop on your wireless carrier's airwaves.

Your cellphone carrier's highway is like a private toll road. Unlike with WiFi, on cellular plans you pay your provider a certain amount every month for the ability to use its exclusive network. Your provider's airwaves operate on different frequencies than WiFi, and in some places there might be more unused bandwidth, which may speed up your downloads.

Cellphone carriers upgrade their networks to be faster and wider by building more cell towers, by upgrading the big, fat pipes that carry data from the towers to the rest of the Internet and by adding more airwaves to the mix to widen the toll road.

But nobody controls WiFi. It's a public good - meaning anybody can send and receive data over it, free of charge. That's why so many start-ups and new devices start out communicating with the Internet over these "unlicensed" airwaves. And it's why many policy advocates have urged federal regulators to designate more parts of the radio spectrum for unlicensed use.

As part of a recently concluded auction of airwaves, the Federal Communications Commission, the nation's top telecom regulator, has set aside a big chunk of spectrum for WiFi and other unlicensed applications. And the agency's chairman, Ajit Pai, told a Senate committee Wednesday that he hopes to explore other opportunities in the area.

"If we give these unlicensed innovators wide swaths of spectrum - low-, mid- and high-band - there's no telling what kind of innovations they may be able to pioneer," Pai said.

As for whether home Internet is always supposed to be faster than mobile Internet: Not always, particularly in places where fixed broadband is expensive to build or lacks competition.

Mobile Internet has also gotten a lot more reliable since the early days, and the United States is known as one of the world's leaders in 4G LTE technology. Not wanting to lose that lead, many carriers such as AT&T and Verizon are currently racing to pilot next-generation 5G data.