How Does Wi-Fi Work?
Find out how your internet connection travels through the air.
W-Fi uses modified radio waves to send internet data through the air. Devices (like your smartphone) have little radios and antennas that receive these waves and convert them into usable data. That’s a simplified explanation, but we’ll go into more detail if you’re curious about the specifics.
What is Wi-Fi?
Wi-Fi is a form of communication that uses radio waves to carry data through the air. It eliminates the need for wired connections, so you can access the internet tether-free. Just tap on a network name displayed on your wireless device and you’re connected to the internet.
However, the terms Wi-Fi and internet are not one and the same. You need a modem for an internet connection and a router for a Wi-Fi connection. If you don’t have a modem, then your Wi-Fi connection can’t access the internet.
What do you need for Wi-Fi?
To get Wi-Fi, you need a wireless router to create a wireless local area network (WLAN). But to get wireless internet, you must have a modem connected to your router. The modem is the only device that can translate your provider’s internet signals into data your router can use.
Check out our article about modems and why you need them for internet to see how your router interacts with your modem.
How Wi-Fi works simplified
Before you can even use Wi-Fi, your wireless device must connect to an access point—in this case, your router.
Connecting to a router
First, your wireless device sends out a query asking, “Who’s out there?” Your router responds by saying, “I’m here, and this is my MAC address.”
Your wireless device then asks, “Can I join? Here’s my MAC address.” The router verifies that your device’s address isn’t banned from the network and says, “Sure, you can join.”
After the initial introduction, your device sends information about its preferred encryption types. The router receives the information, creates an Association ID for your device, and sends a response.2
Finally, your device and router enter the four-way handshake phase—this process encrypts their connection. After that, the router assigns an IP address to your device so you can surf the internet.
When you disconnect and attempt to reconnect, most of the initial introductions are already done. Your device shakes hands with the router and receives its new IP address.
We detail the step-by-step process in the how Wi-Fi devices technically connect section.
Communicating with the router
Your router places the two basic units of data (ones and zeroes) into an ordered line called a bitstream and converts that stream into a digital wave. On paper, it looks more like a cityscape than the typical hills and valleys of analog radio.
Your router then places that digital wave—think of it as an oddly shaped boat—onto a river of energy (radio waves) that’s conformed to carry the boat upstream or downstream on the 2.4 GHz or 5 GHz band.
After that, your device receives and removes the digital boat from the river and converts it into data your device can use. Reverse the process when your device sends data to the router.
If you want a more detailed explanation, we list the steps in the how Wi-Fi technically works section.
How Wi-Fi is similar to AM and FM radio
Wi-Fi is another form of transmitting a signal over the air. We’ll compare it with AM and FM radio so you can see where Wi-Fi resides compared to music radio and why it has a limited reach.
Wi-Fi is the cousin to AM and FM radio
A radio wave is an oscillation of electromagnetic energy used in communication. Amplitude modulation (AM) and frequency modulation (FM) are the two most familiar types of radio, which place audio signals onto carrier radio waves—again, the river and boat scenario.
Why use carrier waves?
Carrier waves are needed because you can’t send raw audio and data signals through the air without a very tall antenna. Raw signals have an extremely low frequency with really long wavelengths that require lots of amplification. The antenna needs to be at least one-fourth the size of a wavelength.
Carrier waves enable the use of small antennas because they use higher frequencies and shorter wavelengths than audio and data signals. The lowest Wi-Fi frequency (2.401 GHz) requires an antenna just over an inch long because it’s one-fourth the size of the wavelength.
What is a frequency?
If you map a radio wave on a graph, it resembles a series of peaks and valleys. A radio wave cycle consists of one peak and one valley. This cycle repeats, creating a continuous flow of energy.
Frequency is the number of cycles per second. The higher the frequency, the more peaks and valleys you’ll see each second. Frequency is measured in hertz, so if 1 Hz equals one cycle per second, 5 Hz equals five cycles per second.
For example, let’s compare AM to FM radio:
|Cycles per second
That’s a lot of cycles per second for sure, but it doesn’t come close to Wi-Fi.
How Wi-Fi fits in
Wi-Fi uses radio waves with a faster frequency than AM and FM radio. While AM radio is measured in kilohertz and FM radio in megahertz, Wi-Fi is measured in gigahertz. This measurement is why you see Wi-Fi connections labeled as 2.4 GHz and 5 GHz—which are a generalization of frequency ranges.
The lowest 2.4 GHz frequency (2.401 GHz) packs 2,401,000,000,000 cycles into each second. Crazy, right? Now just imagine how much data you can cram into each cycle (we can’t), and you’ll see why Wi-Fi uses the 2.4 GHz and 5 GHz bands.
How to improve your Wi-Fi performance
If you’re looking to find ways to improve your Wi-Fi connection, here’s a list of a few common problems and how to fix them.
Problem: Your Wi-Fi speeds are slow
Unplug your router, wait 30 seconds, and then plug it back in to see if your speeds improve. If not, you may need to change frequency bands on your router, change the channel on your router, or upgrade to a faster router. You may even need a faster internet plan if your current connection can’t handle your traffic.
Problem: You have a weak Wi-Fi signal
Move your router to a central and elevated location. Position at least one external antenna horizontally (if you can) for better Wi-Fi access on another floor. You can also try moving closer to the router if it’s already placed in the best location.
FAQ about Wi-Fi
|Max speed (per stream)
|802.11ac Wave 1
|802.11ac Wave 2
* The Wi-Fi Alliance introduced a new naming scheme in 2018 to make product identification easier. For example, 802.11ax or Wireless AX is now called Wi-Fi 6.
|Distance (between each wave)
|Typical max range
|Wi-Fi 5 GHz
|75 feet indoors
150 feet outdoors
|Wi-Fi 2.4 GHz
|150 feet indoors
300 feet outdoors
|100 miles in the daytime
200+ miles at night
Don’t let those numbers fool you. A router can broadcast a 2.4 GHz signal up to 150 feet indoors and up to 300 feet outdoors. The 5 GHz band has half the range. In contrast, AM radio can broadcast hundreds of miles at night because the radio waves can bounce off the ionosphere.3
In all the cases above, higher frequencies translate into shorter ranges.
Here’s what goes on between a host and client device using a step-by-step format.
Step-by-step breakdown of Wi-Fi
In this example, your router is the transmitter and your smartphone is the receiver.
On the transmitter
Step 1: The router receives electrical impulses from the Ethernet port (WAN) and interprets them as a bitstream.
Step 2: The router converts the bitstream into a digital wave.
Step 3: The digital wave (or input signal) is moved to the modulator, where it’s superimposed onto an analog radio frequency carrier wave.
Step 4: The modulated wave moves to the amplifier. The router increases the signal’s amplitude to transmit it across the open air.
Step 5: The amplified modulated RF signal moves to the antenna(s) and is released.
On the receiver
Step 1: The smartphone absorbs the weakened modulated RF signal via its antenna(s).
Step 2: The weakened signal passes through an amplifier.
Step 3: The amplified modulated RF signal moves to the demodulator in your device.
Step 4: The demodulator separates the digital wave (or output signal) from the analog RF carrier wave.
Step 5: The digital wave is converted back into ones and zeroes your smartphone can use.
The receiver includes an amplifier because radio waves weaken and disperse over distance according to the inverse-square law of physics. That means the intensity of emitted radiation decreases as you move away from the source.1 A modulated radio wave must be at a specific strength before the receiver can remove the data wave, so it’s amplified.
For example, modified radio waves must have an amplitude above -69 dBm to remove data transferred over the air at 300 Mbps from a Wi-Fi 4 router.
Every device that supports Wi-Fi has a radio frequency transceiver consisting of a transmitter and a receiver.
Step-by-step breakdown of connecting to Wi-Fi
Here’s a detailed step-by-step list of how your wireless device—a smartphone in this example— connects to a router for the first time.
Step 1: Your smartphone sends a probe request to discover all Wi-Fi networks within range. This request includes information about the smartphone’s supported Wi-Fi standards and its data rates.
Step 2: A router receives the probe, verifies that it can support at least one data rate, and then replies with a probe response containing its MAC address.
Step 3: Your smartphone sends an authentication probe containing its MAC address, asking to join the wireless network.
Step 4: The router consults its list of banned devices and verifies that your smartphone’s MAC address is or is not on the list. The router then replies with an authentication response.
Step 5: Your approved smartphone sends an association request containing information about its preferred encryption types.
Step 6: The router creates an Association ID for your smartphone and replies with an association response.
Step 7: The router and your smartphone enter a four-way handshake phase in which they establish an encrypted connection.
Step 8: The router assigns a private IP address to your smartphone.
- Georgia State University, “Inverse Square Law, Radiation.” Accessed October 5, 2021.
- NetBeez, “Station Authentication and Association,” July 25, 2018. Accessed October 7, 2021.
- Federal Communications Commission, “Why AM Stations Must Reduce Power, Change Operations, or Cease Broadcasting at Night.” Accessed October 25, 2021.
- Apple. “Recommended Settings for Wi-Fi Routers and Access Points.” Accessed November 3, 2021.
Author - Kevin Parrish
Kevin Parrish has more than a decade of experience working as a writer, editor, and product tester. He began writing about computer hardware and soon branched out to other devices and services such as networking equipment, phones and tablets, game consoles, and other internet-connected devices. His work has appeared in Tom’s Hardware, Tom's Guide, Maximum PC, Digital Trends, Android Authority, How-To Geek, Lifewire, and others. At HighSpeedInternet.com, he focuses on network equipment testing and review.
Editor - Rebecca Lee Armstrong
Rebecca Lee Armstrong has more than six years of experience writing about tech and the internet, with a specialty in hands-on testing. She started writing tech product and service reviews while finishing her BFA in creative writing at the University of Evansville and has found her niche writing about home networking, routers, and internet access at HighSpeedInternet.com. Her work has also been featured on Top Ten Reviews, MacSources, Windows Central, Android Central, Best Company, TechnoFAQ, and iMore.