Abstract :
It was September 1989, and the cellphone industry was booming. Companies were building new towers as fast as they could, using the prevailing analog technology, but they were encountering problems with capacity and quality of service. Earlier that year, the industry had decided to move to digital transmission using time-division multiple access. TDMA shared the airwaves by slicing up each available frequency channel into time slots. A caller´s phone transmitted digitized signals in short bursts during the slot assigned to the handset. It wasn´t a particularly efficient use of the broadcast spectrum, but it worked.
