How Wi-Fi Works

The 90-second version

• Your broadband cable brings data into your router as electrical or optical pulses
• The router converts that data into radio waves using a transmitter chip and antenna
• Radio waves travel through air at the speed of light, encoding data as tiny changes in wave amplitude or phase
• Your device’s wireless adapter (NIC) picks up those waves and decodes them back into data
• Everything is encrypted with WPA3 so neighbours can’t eavesdrop
• Multiple devices share the airwaves simultaneously using a technique called OFDM — they divide the channel into hundreds of sub-frequencies and take turns in microsecond-long time slots

What exactly is Wi-Fi?

Wi-Fi is shorthand for a family of wireless networking standards defined by the IEEE 802.11 specification. The name was coined by a marketing consultancy in 1999 and doesn’t actually stand for anything — the “wireless fidelity” backronym is retroactive and unofficial.

The standard defines how radio signals encode and transmit data between devices. Different generations — 802.11b, g, n, ac (Wi-Fi 5), ax (Wi-Fi 6), and be (Wi-Fi 7) — use different frequencies, channel widths, and modulation schemes to push more data faster.

How radio waves carry data

A radio wave is an oscillating electromagnetic field. Your router manipulates this wave to represent 0s and 1s through a process called modulation.

Modern Wi-Fi uses Quadrature Amplitude Modulation (QAM), which tweaks both the amplitude (height) and phase (timing) of the wave simultaneously. Wi-Fi 6 uses 1024-QAM, meaning each symbol can represent 10 bits. Wi-Fi 7 pushes this to 4096-QAM — 12 bits per symbol.

The wave carrier itself operates at either 2.4 GHz (2.4 billion oscillations per second) or 5 GHz. The numbers refer to the carrier frequency, not data speed.

2.4 GHz vs 5 GHz: the real tradeoff

This is where most people have misconceptions.

2.4 GHz:

• Longer wavelength (~12.5 cm) — penetrates walls better
• Shared with Bluetooth, microwaves, and baby monitors → congestion
• Maximum speed: ~600 Mbps (Wi-Fi 5)

5 GHz:

• Shorter wavelength (~6 cm) — absorbed by walls more easily
• Much less crowded spectrum, more channels available
• Maximum speed: ~3.5 Gbps (Wi-Fi 6)

6 GHz (Wi-Fi 6E and Wi-Fi 7):

• Newest band, enormous uncrowded spectrum
• Minimal interference
• Requires recent hardware

The practical takeaway: use 5 GHz when you’re close to the router; 2.4 GHz when walls are in the way or your device is old.

OFDM: how dozens of devices share one channel

The channel your router broadcasts on is only 20–160 MHz wide. So how does it serve 30 devices at once without chaos?

Orthogonal Frequency Division Multiplexing (OFDM) splits the channel into hundreds of narrow sub-carriers (52 in Wi-Fi 4, up to 2,000+ in Wi-Fi 7). Each device gets its own slice of sub-carriers, and the router schedules transmissions in tiny time slots called TXOPs.

Wi-Fi 6 introduced OFDMA — the “A” stands for Access — which lets the router allocate different sub-carriers to different devices within the same transmission, dramatically improving efficiency in dense environments like offices and stadiums.

WPA3: how encryption keeps your traffic private

When you enter a Wi-Fi password, your device and the router perform a handshake — a mathematical exchange that creates a unique shared encryption key for your session, even though both sides start with the same passphrase.

WPA3 (the current standard, replacing WPA2 in 2019) uses Simultaneous Authentication of Equals (SAE), also called Dragonfly. Unlike the older WPA2 PBKDF2 method, SAE is resistant to offline dictionary attacks — even if someone captures your handshake, they can’t brute-force the password from it.

Once connected, all traffic is encrypted with AES-128 or AES-256, the same standard banks use.

How your device gets an IP address (DHCP)

Your device doesn’t know its IP address before connecting. The router runs a DHCP server (Dynamic Host Configuration Protocol) that hands out addresses from a pool.

The sequence:

1. Discover — your device broadcasts: “Is there a DHCP server?”
2. Offer — the router responds: “Yes, here’s 192.168.1.47, it’s yours for 24 hours”
3. Request — your device replies: “I’ll take it”
4. Acknowledge — router confirms the lease

After 50% of the lease time, your device quietly renews it in the background.

The mental model: Wi-Fi is a walkie-talkie with very good manners

Picture hundreds of people in the same room (the Wi-Fi channel) all trying to talk at once. OFDM is like giving each person their own pitch to speak at — they can all talk simultaneously without interrupting each other. The router is the moderator: it assigns pitches, enforces time limits, and translates everyone’s words (data) into the shared language (IP).

When the room is empty (single device, late at night), you can have the whole channel to yourself and go much faster.

Common misconceptions

“Wi-Fi 6 is always faster than Wi-Fi 5.” Not necessarily for a single device. Wi-Fi 6’s main improvements are efficiency in crowded environments. If you’re the only device connected, Wi-Fi 5 hardware on a good 5 GHz channel may perform identically.

“Turning Wi-Fi off at night saves significant energy.” Your router uses roughly 3–15 watts whether devices are connected or not. The saving is negligible.

“A higher Wi-Fi password is more secure than a shorter complex one.” With WPA3, length matters more than complexity. correcthorsebatterystaple (four random words) is far more secure than P@$$w0rd and easier to remember.

“Wi-Fi goes through walls.” Partly. 2.4 GHz penetrates better than 5 GHz, but concrete, brick, and metal all absorb radio waves significantly. A concrete wall can reduce 5 GHz signal by 15–25 dB — enough to halve your throughput or disconnect entirely.

Wi-Fi generations at a glance

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