Mixing Signals up to Make them Work Better
Multiplexing
Time-division multiplexing (top only)
Frequency-division multiplexing (top only)
Wavelength division multiplexing
Carrier frequency
Modulation (top only)
Amplitude modulation (top and AM vs FM section)
Frequency modulation (top and Applications in Radio section)
Code-division multiple_access (top only)
TDMA
FDMA

Data Compression and Media Formats
Codec
Data compression (theory is optional)
Video codec
Video compression
Audio data compression (top and skim the rest)
Mp3 (top, Overview, and Quality of MP3 audio, only then skim the rest)
ID3 (top and skim the rest)
Advanced audio coding (top and AAC's improvements over MP3
Comparison of container formats (understand, don't memorize)
Lossy data compression
Lossless data compression (top only)
MPEG
Video CD
DVD (skip Technical Information)
MPEG-4

Switching
Circuit switching
Public switched telephone network
Packet switching (skip Controversy section)
Packet
Network switch (top and then skim the rest)

Protocols
Communications protocol
HyperText Transfer Protocol (top only)
Internet Message Access Protocol
Post Office Protocol
File Transfer Protocol (top only)
Simple Mail Transfer Protocol (top only)
Voice over IP
File sharing
Napster
Peer-to-peer
EDonkey network (first two paragraphs only)
Gnutella (top only)
BitTorrent

Satellites
Transmission medium
Communications satellite
Geostationary orbit
Low Earth Orbit
Latency
Gps (skip Technical description section)
Galileo positioning system (top and skim the rest)
Iridium (skip Technical details section)
Satellite radio (top and Satellite radio vs other formats section, then skim the rest)