Saturday, 24 April 2010

CWNA Study Guide Chapter 1 Communications Fundamentals Key Learning Points

These are what I feel are the key learning points from chapter 1 of the CWNA Study Guide, knowing and understanding these will help pass the CWNA exam

Standards Bodies

IEEE - Institute of Electrical and Electronics Engineers
FCC - Federal Communications Commission
ITU-R - International telecommunication Union - Radiocommunication Sector
TELEC - Telecom Engineering Center
ETSI - European Telecommunications Standards Institute
WECA - renamed to Wi-Fi Alliance in 2000
WFA - Wi-Fi Alliance
ISO - International Standards Organisation

Wi Fi Alliance Programs

802.11 a/b/g/n
WPA2 - based on 802.11i
WMM - based on 802.11e
WMM-PS - WMM Power Save
WiFi Protected Setup - easy setup for home wifi networks using PIN, push button, usb etc
CWG-RF (Converged Wireless Group - RF Profile) - defines performance metrics for wi-fi ad cellular radios in converged handsets ensuring both technologies perform well in the presence of each other
Voice Personal - for SOHO environments supprting upto 4 calls

Future Wi Fi Alliance Programs

Voice Enterprise - due in 2010

RF Fundamentals

Carrier wave is a signal that is modified (modulated) to convey data

Each of the following can be modulated to convey information

Frequency
Amplitude
Phase

Keying Methods

Know the difference between current state and state transition.
Keying methods are also know as modulation techniques.b

ASK - Amplitude Shift Keying
Varies amplitude and uses current state
Susceptible to interference

FSK - Frequency Shift Keying
Varies frequency and uses current state
Found in some legacy 802.11 systems

PSK - Phase Shift Keying
Varies the phase and uses state transition
If phase changes per symbol period "1"
If no phase change per symbol period "0"
Advanced versions of PSK can encode multiple bits per symbol period.

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