How Wi-Fi Works
How wireless LANs encode data onto radio waves — channels, modulation, collisions, and why your Wi-Fi speed depends on walls, neighbors, and channel width.
Wi-Fi is a set of standards (IEEE 802.11) for sending data over unlicensed radio bands — 2.4 GHz, 5 GHz, and now 6 GHz. It takes the same packets your router would send down a wire, encodes them onto a carrier wave with phase and amplitude modulation, and negotiates shared access to the air between every device within range. The magic to understand is not the radio but the coordination.
The basics
Your router and devices trade packets by modulating a carrier: ON/OFF-style amplitude, phase shifts, or — in modern OFDMA — thousands of narrow subcarriers each carrying a few bits (QAM). Higher frequencies offer wider channels and faster rates but penetrate walls worse; 2.4 GHz penetrates walls and crowds (only 3 non-overlapping channels), 5 and 6 GHz are faster but shorter-range. Channels are 20/40/80/160 MHz wide; a 160 MHz channel is why one neighbor's router can halve yours.
The shared-air problem
All devices on a channel share one collision domain. Wi-Fi avoids collisions with CSMA/CA: listen before transmitting, back off a random interval, and acknowledge every frame. There is no collision detection over radio (a transmitter cannot hear the network while transmitting), so the protocol is collision-avoidance with acknowledgments and retransmissions — the root of why one slow legacy device can drag a whole cell's throughput down.
What the speeds mean
The advertised number (Wi-Fi 6 = 2.4 Gbps) is the PHY rate: raw modulated bits at ideal signal, no retransmissions, best-case coding. Real throughput is typically 40–70% of PHY rate, halved again by walls, distance, and neighbors sharing the channel. The single highest-leverage fix is spectrum: 6 GHz (Wi-Fi 6E/7) has 1,200 MHz of clean spectrum where the microwave oven and the neighbor's network are not. Related reading: domain name system and http caching for what happens after the radio link delivers.
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networking radio wifi wireless