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Overview

Summary

  • Wi-Fi is the common name for the family of wireless LAN standards defined by IEEE 802.11; the "Wi-Fi" branding and interoperability certification itself is managed separately by the Wi-Fi Alliance.
  • Each new 802.11 amendment adds speed, efficiency, or new spectrum — but generations are cumulative and largely backward-compatible, which is why a 15-year-old laptop can usually still join a brand-new router's network, just slower.
  • Security has evolved in step with the radio standards — WEP → WPA → WPA2 → WPA3 — and is just as important to understand as the radio side, since a fast network with broken security isn't a safe one.

The 802.11 Standard Family

Each amendment historically had its own letter suffix; since 2018 the Wi-Fi Alliance also assigns each a simple generation number for consumer-facing marketing:1

IEEE Amendment Wi-Fi Generation Year Max Band(s) Headline Feature
802.11b — 1999 2.4 GHz First mass-market Wi-Fi, 11 Mbps
802.11a — 1999 5 GHz Same era as 11b, less interference, less range
802.11g — 2003 2.4 GHz 11a's speed (54 Mbps) on 11b's band
802.11n Wi-Fi 4 2009 2.4 & 5 GHz Introduced MIMO
802.11ac Wi-Fi 5 2013 5 GHz Wider channels, MU-MIMO (downlink)
802.11ax Wi-Fi 6 / 6E 2019 / 2020 2.4, 5 GHz (6E adds 6 GHz) OFDMA, better efficiency in crowded networks
802.11be Wi-Fi 7 2024 2.4, 5, 6 GHz Multi-Link Operation (MLO), 320 MHz channels

Table 1. IEEE 802.11 Amendments and Wi-Fi Generation Names

Wi-Fi 6E isn't a new radio standard

"6E" is still 802.11ax — the "E" just marks that the device is certified to also operate in the newly opened 6 GHz band, which didn't exist as unlicensed spectrum when 802.11ax first launched. Wi-Fi 6E and Wi-Fi 6 devices run identical PHY/MAC logic; 6E devices just have more (cleaner) spectrum available to use it in.

Frequency Bands & Channels

Wi-Fi operates in unlicensed spectrum, split into three bands with very different trade-offs:2

Band Range Channel Width Range vs. Speed Congestion
2.4 GHz 2.400 – 2.4835 GHz 20/40 MHz Best range, penetrates walls well Most crowded — shared with Bluetooth, microwaves, baby monitors
5 GHz ~5.150 – 5.895 GHz 20/40/80/160 MHz Faster, shorter range Moderate
6 GHz 5.925 – 7.125 GHz up to 320 MHz Fastest, shortest range Least crowded — Wi-Fi 6E/7 only

Table 2. Wi-Fi Frequency Bands

2.4 GHz only has 3 non-overlapping channels

In the 2.4 GHz band, only channels 1, 6, and 11 (in most regions) avoid overlapping with each other. Any other channel choice causes adjacent-channel interference with nearby networks — this is the single most common cause of a crowded-apartment Wi-Fi slowdown, and why most routers default to auto-selecting one of those three.

OSI Layer

Wi-Fi OSI Layer

Figure 1. Wi-FI OSI Layer

802.11 only defines the bottom two layers of the OSI model — everything above that (IP addressing, TCP, HTTP, your browser) is completely unaware of whether it's running over Wi-Fi, Ethernet, or anything else.6

OSI Layer 802.11 Scope Covers
Layer 1 — Physical (PHY) Fully defined by 802.11 Radio frequencies, modulation (OFDM/OFDMA), channel width, MIMO antenna handling
Layer 2 — Data Link Split into two sublayers See below
-- MAC sublayer Fully defined by 802.11 Frame formats, medium access (CSMA/CA), addressing (BSSID/SSID), association, security handshakes
-- LLC sublayer Shared with wired Ethernet (802.2) Hands frames up to Layer 3 in a form identical to what a wired NIC would produce
Layer 3 and above Not part of 802.11 at all IP, TCP/UDP, and every protocol above — identical regardless of the underlying link

Table 3. Where 802.11 Sits in the OSI Model

This is why Wi-Fi and Ethernet interoperate so easily

Because 802.11's MAC hands frames up through the same LLC sublayer that wired Ethernet uses, an IP packet doesn't need to be reformatted when it crosses from a Wi-Fi client to a wired switch port — as far as Layer 3 and above are concerned, the two link types are interchangeable.

Network Architecture

A Wi-Fi network is built from a small set of standard roles and groupings:3

Term Meaning
STA (Station) Any device with a Wi-Fi radio — laptop, phone, IoT sensor
AP (Access Point) The STA that bridges the wireless network to a wired backbone
BSS (Basic Service Set) One AP plus all STAs currently associated with it
BSSID The AP's radio MAC address — the unique identifier of that specific BSS
SSID The human-readable network name (e.g. "HomeNetwork") — can be shared by multiple BSSs
ESS (Extended Service Set) Multiple BSSs (multiple APs) joined under one SSID, letting a client roam between them seamlessly

Table 4. Wi-Fi Network Architecture Terms

Wi-Fi Architecture Example

Figure 2. An example of a service set called WiFi Wikipedia consisting of two basic service sets. The clients automatically roam between the two BSSs without the user having to explicitly connect to the second network.4

Security Evolution

Wi-Fi security has moved through four major generations, largely tracking the radio standard's own evolution:5

Protocol Year Status Key Weakness / Improvement
WEP 1997 Broken, do not use Static key, trivially crackable in minutes
WPA 2003 Deprecated Interim fix (TKIP) for WEP hardware, itself since broken
WPA2 2004 Still widely used, being phased out AES-CCMP encryption; vulnerable to offline dictionary attacks on weak passphrases (and the KRACK protocol flaw, since patched)
WPA3 2018 Current standard SAE (replaces PSK) resists offline dictionary attacks; mandatory for Wi-Fi 6E certification

Table 5. Wi-Fi Security Protocol Evolution

What SAE actually fixes

WPA2's 4-way handshake exposes enough data for an attacker to capture and try passwords offline, as fast as their hardware allows. WPA3's SAE (Simultaneous Authentication of Equals) handshake requires an attacker to interact with the live AP for each individual guess, making large-scale offline cracking impractical even against a weak passphrase.

Useful Resources

  1. Wi-Fi Alliance. (n.d.). Discover Wi-Fi — Generations. https://www.wi-fi.org/discover-wi-fi ↩

  2. IEEE. (n.d.). IEEE 802.11 Standard. https://standards.ieee.org/ieee/802.11/7028/ ↩

  3. IEEE. (n.d.). IEEE 802.11-2020 — Part 11: Wireless LAN MAC and PHY Specifications. https://standards.ieee.org/ieee/802.11/7028/ ↩

  4. Wikipedia contributors. (n.d.). Wi-Fi. Wikipedia. https://en.wikipedia.org/wiki/Wi-Fi ↩

  5. Wi-Fi Alliance. (n.d.). Security. https://www.wi-fi.org/discover-wi-fi/security ↩

  6. IEEE. (n.d.). IEEE 802.11-2020 — Part 11: Wireless LAN MAC and PHY Specifications. https://standards.ieee.org/ieee/802.11/7028/ ↩