Wireless Networks & Wi-Fi Standards

Wireless Networking allows devices to connect to a network without physical cables, using radio waves. The dominant standard for wireless LANs is IEEE 802.11, commercially known as Wi-Fi.

1. How Wi-Fi Works

A Wireless Access Point (AP) connects to a wired network (Ethernet) and broadcasts a radio signal. Wireless devices (laptops, phones) detect this signal, authenticate, and join the network. The AP acts as a bridge between the wireless and wired worlds.

• BSS (Basic Service Set): A single AP and all its associated wireless clients.
• SSID (Service Set Identifier): The human-readable name of the Wi-Fi network.
• Frequency Bands: 2.4 GHz (longer range, more interference, fewer channels) and 5 GHz (shorter range, less interference, more channels). Wi-Fi 6E added 6 GHz.

2. Wi-Fi Standards Evolution

3. Wi-Fi Security

• WEP (Wired Equivalent Privacy): The original security standard. Completely broken; can be cracked in minutes. Never use it.
• WPA (Wi-Fi Protected Access): Used TKIP encryption. Improved but still vulnerable.
• WPA2: Uses AES-CCMP encryption. The standard for over a decade.
• WPA3: The latest standard. Uses SAE (Simultaneous Authentication of Equals) for stronger password-based authentication and provides forward secrecy.

4. Challenges

• Hidden Node Problem: Two devices can communicate with the AP but not with each other, leading to collisions at the AP. Solved by RTS/CTS handshake (covered in CSMA/CA).
• Interference: Microwave ovens, Bluetooth devices, and neighboring Wi-Fi networks on the same channel cause interference on 2.4 GHz.
• Signal Attenuation: Walls, floors, and distance reduce signal strength and throughput.