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Transmission Media
GUIDED MEDIA
Guided media, which are those that provide a conduit from one device to another, include twisted-pair cable, coaxial cable, and fiber-optic cable.
UNGUIDED MEDIA: WIRELESS
Unguided media transport electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication.
Wireless Channels
 Are subject to a lot more errors than guided media channels.
 Interference is one cause for errors, can be circumvented with high SNR.
 The higher the SNR the less capacity is available for transmission due to the broadcast nature of the channel.
 Channel also subject to fading and no coverage holes.