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Time division multiple access (TDMA) is a channel access method (CAM) used to facilitate channel sharing without interference. TDMA allows multiple stations to share and use the same transmission channel by dividing signals into different time slots. Users transmit in rapid succession, and each one uses its own time slot. Thus, multiple stations (like mobiles) may share the same frequency channel but only use part of its capacity.
Examples of TDMA include IS-136, personal digital cellular (PDC), integrated digital enhanced network (iDEN) and the second generation (2G) Global System for Mobile Communications (GSM).
TDMA allows a mobile station's radio component to listen and broadcast only in its assigned time slot. During the remaining time period, the mobile station may apply network measurements by detecting surrounding transmitters in different frequencies. This feature allows interfrequency handover, which differs from code division multiple access (CDMA), where frequency handover is difficult to achieve. However, CDMA allows handoffs, which enable mobile stations to simultaneously communicate with up to six base stations.
TDMA is used in most 2G cellular systems, while 3G systems are based on CDMA. However, TDMA remains relevant to modern systems. For example, combined TDMA, CDMA and time division duplex (TDD) are universal terrestrial radio access (UTRA) systems that allow multiple users to share one time slot.