1. Authentication
1.1. Open authentication
1.1.1. Open authentication provides wireless connectivity to any wireless device and should only be used in situations where security is of no concern.
1.2. Shared key authentication
1.2.1. is a process by which a computer can gain access to a wireless network that uses the Wired Equivalent Privacy (WEP) protocol. With SKA, a computer equipped with a wireless modem can fully access any WEP network and exchange encrypted or unencrypted data.
2. Discovering APs
2.1. Passive mode
2.1.1. The AP openly advertises its service by periodically sending broadcast beacon frames containing the SSID, supported standards, and security settings.
2.2. Active Mode
2.2.1. Wireless clients must know the name of the SSID.
3. Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
3.1. Wifi System - Half duplex
3.1.1. Cause collision
3.2. Solution : Distributed Coordination Function (DCF).
3.2.1. transmits only if the channel is clear
3.2.2. 1. wireless client need to send data 2. wireless client sense media (idle or not?) 3. if not idle, wait for random backoff time 4. if idle, send RTS frame to AP 5. if available, AP sends CTS frame to wireless client 6. wireless client sends data 7. if received, receiver sends ACK frame to sender