Time Division Multiple Access (TDMA)

Now that we’ve seen how CDMA uses what can be referred to as a “spread spectrum” technology to allow users to share a bandwidth of frequencies, we will begin to explore other multiplexing concepts. Today’s term divides bandwidth access by time rather than a special coding scheme (CDMA).

Time Division Multiple Access (TDMA): A technique for transmitting a number of separate data, voice and/or video signals one after another. With Time Division multiplexing, you “sample” each voice conversation, interleave the samples, send them on their way, then reconstruct the several conversations at the other end. There are several ways to do the sampling. You can sample eight bits (one byte) of each conversation, or you can sample one bit. The former is called “word interleaving”; the latter “bit interleaving”. The basic goal of multiplexing – whether it be time division or any other form – is to save money, to cram more conversations (voice, data, video or facsimile) onto fewer phone lines. Basically, to substitute electronics for copper.




Picture Source: http://en.wikipedia.org/wiki/File:Tdma-frame-structure.png