Radio Access Method

FDMA

In the FDMA (Frequency Division Multiple Access) systems (e.g. NMT, TACS and AMPS) the users are separated by frequency. Each user has an allocated radio frequency for the duration of the call. At call termination the radio resource is released for someone else to use.

TDMA

In the TDMA (Time Division Multiple Access) systems (e.g. GSM, PDC, and D-AMPS) the users are separated by frequency and also by timeslots. This means that on each 200 kHz channel, eight users share the resource by taking turns sending information in so called timeslots. The timeslot is allocated for one user for the duration of the call. The users take turns in sending their information to the network, increasing their output power as they send.

CDMA

In the CDMA (Code Division Multiple Access) systems (e.g. cdmaOne, cdma2000 and WCDMA) all users share the same frequency in a cell, but instead of timeslots they are separated by different codes.