Source : Free On-Line Dictionary of Computing

time division multiplexing
     
         (TDM) A type of {multiplexing} where two or
        more channels of information are transmitted over the same
        link by allocating a different time interval ("slot" or
        "slice") for the transmission of each channel.  I.e. the
        channels take turns to use the link.  Some kind of periodic
        synchronising signal or distinguishing identifier is usually
        required so that the receiver can tell which channel is which.
     
        TDM becomes inefficient when traffic is intermittent because
        the time slot is still allocated even when the channel has no
        data to transmit.  {Statistical time division multiplexing}
        was developed to overcome this problem.
     
        Compare {wavelength division multiplexing}, {frequency division
        multiplexing}, {code division multiplexing}.
     
        (2001-06-27)