L6 - Over much of wireless communication history, different...

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Over much of wireless communication history, different senders in propagation range have been assigned to different frequency bands so they don’t interfere with each other. Radio and television broadcasting operate this way, and earlier cellular telephone communication operated this way.
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Cellular concept with frequency assignments Ideally hexagonal cells, with frequency re-use in well-separated cells. Example of 7 frequency bands with three-cell separation re-use. There is a base station for each cell.
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Within a cell, the assigned frequency band 5 (f for example) is divided among current cellular users. The division was initially frequency multiplexing, one frequency sub-band/user. Later systems used time slots (time division multiplexing). The philosophy for some time was that no two communications within range should send in the same frequency band at the same time. But a way was discovered where in-range communicators could use the same frequency band at the same time! This idea is called Spread Spectrum or CDMA ( Code Division Multiple Access )
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CDMA ( Code Division Multiple Access )
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L6 - Over much of wireless communication history, different...

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