Wifi is a wonderful technology that we all enjoy every day. We’ve become so accustomed to it, that we expect a wifi connection everywhere we go. Before we’ll explore the security implications of wifi networks, we’ll need to get a basic understanding for the underlying infrastructure first. If you already know how cellular and wifi networks work (no, they’re not the same), feel free to skip ahead. Else, buckle up and join me on a deep-dive of our wireless infrastructure.

How cellular technology works

Cellphones received their names because they connect to cellular networks, rather than to cable networks. A “cell” refers to the coverage area that surrounds a particular cellular tower or transmitter.

With cable networks, devices receive data via a copper or fibre cable, with wireless networks, the data is sent “over the air.” Before we go into more detail what this means for wireless security, stay with me for a second, as there are still a few more concepts that we’ll need to cover.

So, how does a cellular tower know whether the data should be sent to you or another phone within the same cell? I’m glad you asked.

Let’s look at what happens when you make a call.

Placing a call with your mobile phone

The tower closest to you picks up the signal from your cellphone.
The tower, also called Base Station, assigns your call a frequency.
The tower sends your message to a Base Station Controller, which acts as a switching point.
Your message travels wirelessly or via wires to the destination tower.
Along the way, the Mobile Switch Center, routes the message from point to point towards the correct destination.
The destination tower forwards the message to the recipient’s cellphone.

If you want a bit more detail, keep reading. Otherwise, skip to the next section.

Your cellphone knows what towers are closeby and their signal strength and when you are placing a call, your phone is sending a radio signal to the closest tower with the best signal.

Your call is assigned an available frequency channel, which basically isolates your call and makes sure it doesn’t overlap with other phone conversations that are happening at the same time.

Your voice is now being “translated” into data that can be transmitted to the recipient. This transmission usually does not happen “over the air” but instead via a fiber optic cables that run underground. From there, the data is processed by a switchboard and routed to its destination. If you are calling a landline, the data is travelling via the cable all the way. If you are calling another cellphone, the data is sent to the tower that closest to your recipient and translated back into radio waves to be sent from the transmitter to the recipient’s cellphone.

Now, what happens if you’re “on the move” during that conversation and cross over to another cell? First, your signal strength will decline and your phone will be looking for another, stronger, signal to connect to. The original tower will then hand your call over to the tower nearest to you. Most of the time this happens flawlessly and you won’t even notice. Sometimes, however, something may go wrong and your call will be dropped.

Roaming

Check out which cell phone towers are closest to you and which carrier operates them, here and here. This brings me to another important concept that I need to quickly cover before we move on: Roaming.

The process I’ve described above referred to same-carrier handoffs. If you are moving into an area, where your provider does not have coverage, your phone call would need to be handed off to another carrier, which is referred to as roaming. The reason why you incur charges when roaming is that your carrier is not servicing you and you’re now using the infrastructure and services of a carrier who is not sending you a monthly bill to cover their costs. Hence, these service charges are passed on to you as roaming fees. These can be extraordinarily high, especially if you’re using your cellphone abroad.

The days of using your mobile phone only for phone calls are gone. So, now that we’ve got a better understanding of how the cellphone network works, let’s look at it from a “data usage” perspective. After all, without mobile data, your smartphone would not be so smart.

How does your smartphone access the Internet?

With your smartphone, you can access the Internet in two ways: Wi-Fi or cellular data, both of which use radio waves. Let’s look at cellular data first.

Similar to making phone calls with your cell phone, cellular data is available only when you are connected to a tower of your network carrier. The process usually unfolds in the same way as it does with making a call.

When you access data with your mobile phone, the process is similar, but there are a few more steps and concepts that we need to add to the equation.

As we have already seen, the mobile switching center (MSC) is responsible for routing voice calls and SMS from your device to the recipient and vice versa. I should mention that it also handles hand-overs from cell to cell and is even involved in charging for the data transmission, so you will get billed for the minutes you’ve spent on the phone, or browsing the internet via your data plan. To do all of this, the MSC accesses the following:

the home location register (HLR) for obtaining information about your phone’s SIM and telephone number.
the base station subsystems (BSS) and UMTS terrestrial radio access network (UTRAN) which handle traffic and signaling.
the visitor location register (VLR), which informs about the location of the mobile phone and provides instructions about which services s/he is allowed to access.
information a handover, such as the anchor MSC, which is where you came from, and the target MSC, which is where you moved to.

When it comes to cellular data, there is one important concept that we need to cover: analog vs. digital. A website or app that you access online consists of data bits that are stored on a server. This data is digital, while the cable infrastructure that makes up the phone network and which eventually transports that data from the server to your phone, is analog. As a result, the MSC also needs to act as a translator to transform digital data into analog and analog to digital.

Now, that you’ve got an overview of how cellular systems work, let’s add wifi to the mix before we move on to wifi security.

How Wi-Fi works

Let’s talk a little bit about Wi-Fi, which by the way is not short for “wireless fidelity,” in fact, it’s not an acronym at all. The term Wi-Fi was just a pun on the acronym “Hi-Fi” (high-fidelity audio) but in reality does not stand for anything. It was coined by a brand consulting company, hired by the Wireless Ethernet Compatibility Alliance (later called Wi-Fi Alliance), to assign a more user-friendly name for the technology that adhere to the IEEE 802.11b Internet standard.

Now with this little history lesson out of the way, let’s learn a bit more about what it actually is and how it works.

In order to connect your phone, laptop, computer, tablet, fridge, fitbit, or other devices to the Internet, you need two elements.

Your device needs to have an in-built piece of technology, called a wireless network card, that allows it to connect to certain wireless networks.
You need a wireless access point, such as a router, to provide you with the actual Internet connection. The wireless access point is radio transmitter and receiver, which is configured with certain settings, such as a network name, ID, and password. Devices that connect to this wireless access point must mirror these settings in order to connect to it.

Another important concept to cover are channels and frequencies. You may have noticed that sometimes your internet connection slows down, particularly at certain time of the day when more people may be using their internet and TV (if you’re with Shaw, for example, where you receive Internet via your television cable). If you have ever called your Internet Service Provider (ISP) to ask for advice, you may have been asked to “change the channel” and see if that takes care of the problem. Let’s look at what goes on behind the scenes here and why that might have increased your Internet speed. But warning: Dense material ahead.

Wireless Channels and Frequencies

Let me start off with a little analogy. Imagine you are talking to a friend in a room full of people who are also trying to talk to one another at the same time. You will likely notice that the more conversations that are happening at the same time (interference), the more information you’ll miss from your friend. This is true with wireless networks as well. The more interference there is, the more network problem you are experiencing.

What would happen if everyone in the room now decided to implement some social-distancing, and spaced out a couple of meters apart? You’d notice that suddenly there’s less interference in your conversation and you can finally hear your friend. The further apart each talking parties are, the lower the interference that everyone will experience.

Let’s look at this from a Wi-Fi perspective, but keep this concept in mind. For Wi-Fi, there are two spectrums available, the 2.4 GHz band and the 5 GHz band. Each spectrum is divided into channels and each channel has its own frequency and bandwidth. If you’re curious, the 2.4 GHz band is divided into 14 channels, each 20MHz wide and spaced 5 MHz apart. In the 5GHz band, we have channels ranging from 36 up to 165, each 20MHz wide.

If your ISP offers both and you’re a bit torn which one to use, here’s a run-down: The 2.4 GHz band provides coverage at a longer range (20–30 feet || 6-9 meters) but transmits data at slower speeds while the 5 GHz band provides less coverage (10–15 feet || 3-5 meters) but transmits data at faster speeds. And stay tuned, because Wi-Fi 6 is on the way, using 14 additional 80 MHz channels and 7 additional 160 MHz channels in 6 GHz.

Of these 14 channels, only channel 1-11 can be used in North America, while in Europe channels 1-13 are available, and in Japan all 14 channels can be used.

In case you’re wondering why North America is so restrictive, it’s because channels 12-14 are reserved for other, important services. So even if you see the option to connect to these channels in low-power mode, please steer clear of that. Channel 14 is actually forbidden to access in North America, because this frequency is used for the “Industrial Scientific or Medical band (ISM). Most home routers and commercial routers don’t even give you these options and now you know why.

Another fun fact: The channels with the least overlap are channels 1, 6, and 11. So, if you are accessing the internet in a high-interference environment, consider switching to one of these three channels and see if your internet connectivity improves.

Awesome, now that we have a more broad understanding of the individual components, let’s connect the dots.

How Wi-Fi connection works

A wireless access point broadcasts its SSID to all wireless devices in the are, advertising its existence.
Your device scans your area for wireless networks and picks up all SSID broadcasts of routers that are configured to broadcast their SSID and shows you a list of devices that are available to you.
You connect to the wireless access point.
You open your browser or app, to access a particular server (e.g. email, website). This creates a “request” that your device will send to the server in question, to access its information.
Your device’s wireless adapter translates this request into a radio signal and transmits it via an antenna.
The receiving wireless router decodes the information, packages it accordingly, which includes attaching the recipient’s address, etc. and sends the information to the Internet via a wired Ethernet connection.
The information travells across the wire to the destination router, which passes on the information to the receiving device.

When the data comes back to your device, in the form of a website that you’re accessing or an app that you’re interacting with, the process unfolds in reverse.

If you’ve ever listened to the radio, you know that radio frequency waves can be picked up from more than one device. The same is true for information you request and send via Wi-Fi. As a result, there is always a risk that your signal might be intercepted by an attacker. This is why for mobile phones Wi-Fi security and device security are incredibly important. You wouldn’t want an attacker who’s connected to the same network to read your Instagram login information, while you’re checking your social media from your favourite coffee shop. To learn more about mobile security, feel free to read the following:

Difference between cellular networks and Wi-Fi

	Cellular	Wi-Fi
Access via	Celltower	Router
Transmitter / Receiver	Base station	Access point
Device detection	HLR, VLR, BTs	IP and MAC address
Radio waves	high frequency radio waves	low range radio transmitter
Range	several kilometers	up to 100 meters
Standards governed by	ISPs	IEEE

When to use Wi-Fi or cellular data

Many people always keep their phones connected to Wi-Fi and data, which has several implications, including connection speed, security, and cost.

Connection speed

Wi-Fi is usually faster than data, although this depends heavily on several factors, such as how many people are serviced by the same Wi-Fi router or cellphone tower, the amount of interference, the device’s distance from the router or cellphone tower, as well as obstacles between the device and the antenna (from the router or cellphone tower).

Security

If you’re connected to your home network’s Wi-Fi router and you have done a good job at securing it from attackers, your Wi-Fi connection is likely to be somewhat secure. Mind you, no network is 100% hack-proof, no matter how knowledgeable you are in this area. However, if you’re connected to an unsecured Wi-Fi hotspot, such as a coffee shop or airport, stay away from checking any sensitive information.

When accessing the internet via your cellular data, your browsing will likely be relatively secure (again, no network is 100% hack-proof), because there should be nobody else connected to your personal network, unless you granted others access by creating a non-password-protected hotspot.

Cost

Many ISPs offer unlimited Wi-Fi, while the same is usually not true for cellular data. Even “unlimited data” is not really unlimited, because carriers usually limit the amount of data you can download before they are throttling (slowing down) your connection speed if you continue to use your data.

Also, keep in mind that roaming can quickly become extremely expensive, if you leave your data on while traveling to areas that are not covered by your carrier.

If you are not connected to Wi-Fi and have not disabled app updates via data, automatic updates to your applications may happen via your cellular data, which can increase the cost you’ll be paying for data usage at the end of the month. Also, for all YouTube and Instagram aficionados out there: Be aware that streaming videos and browsing image-heavy websites uses up a lot of your data, so try to switch to Wi-Fi and disable your data services while doing so.

How a MiFi works

If you’ve ever created a hotspot with your mobile phone, you’ve created what’s called a MiFi. There are also several devices on the market that you can either purchase or rent, which act as MiFi hotspots. One example is the little device that you can rent from car rental companies to create a hotspot in your vehicle while on-the-go. MiFi may stand for My Wi-Fi, although there is no official confirmation for the origin of that trademark.

These portable MiFi hotspots usually involve that you connect to a 3G or 4G cellular network which around 5-10 other devices can connect to. A MiFi works in a similar fashion to your home network’s router, with the main difference being that the MiFi device is not connected to a wired network but instead the cellular network.

Understanding the difference between cellular networks and wifi