Cell Phone Development History & Applications

Posts Tagged ‘time division multiple accesses’

TDMA is the acronym for Time Division Multiple Accesses, referring to a digital transmission format.  Basically, what TDMA does is to divide a single radio frequency into time slots so that multiple users can use the same bandwidth at the same time.  One channel is divided into six time slots and each signal is allocated two of the six slots — i.e. 3 different callers on one channel at one time. This concept is illustrated below.  A you can see, this type of transmission enables a more efficient use of the bandwidth in that is fills the "dead air" created by one call with calls between other parties.  TDMA technology is used in second generation Mobile Phone systems know as D-AMPS (or Digital Advanced Mobile Phone Systems).  TDMA uses IS-54 (this first cut at a sstandard) and was replaced by IS-136.  These defined the authentication alogorithms used to encrypt mobile communications.

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