17.2 LAN TRANSMISSION MEDIA

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For a LAN, the transmission medium can be twisted copper cable, coaxial cable, optical fiber, and radio. The topology, data rates, and medium access protocols will differ for the different media.

LANs can be broadly categorized as baseband LANs and broadband LANs. Broadband LANs can span larger distances up to tens of kilometers. Broadband LAN uses frequency division multiplexing, in which multiple channels are used for data, voice, and video. RF modems are required for communication. They operate in unidirectional mode because it is difficult to design amplifiers that pass signals of one frequency in both directions. To achieve full connectivity, two data paths are required—one frequency to transmit and one to receive.

LANs can be broadly classified as baseband LANs and broadband LANs. In a baseband LAN, the baseband signals are transmitted over the medium. In broadband LANs, the signals are multiplexed using frequency division multiplexing.

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