Time-division multiple access

For this reason, an entire time slot has to be dedicated to mobiles attempting to contact the network; this is known as the random-access channel (RACH) in GSM.

Finally, if the mobile is beyond the 35 km cell range of GSM, the transmission will arrive in a neighbouring time slot and be ignored.

[citation needed] In the context of 3G systems, the integration of Time-Division Multiple Access (TDMA) with Code-Division Multiple Access (CDMA) and Time-Division Duplexing (TDD) in the Universal Mobile Telecommunications System (UMTS) represents a sophisticated approach to optimizing spectrum efficiency and network performance.

This separation minimizes interference and allows for continuous data transmission in both directions, making it suitable for environments with balanced traffic loads.

This time-based separation is particularly advantageous in scenarios with asymmetric traffic loads, where the data rates for uplink and downlink differ significantly.

By dynamically allocating time slots based on demand, UTRA-TDD can efficiently manage varying traffic patterns and enhance overall network capacity.

[8][9] The combination of these technologies in UMTS allows for more flexible and efficient use of the available spectrum, catering to diverse user demands and improving the adaptability of 3G networks to different operational environments.

FlexRay protocol which is also a wired network used for safety-critical communication in modern cars, uses the TDMA method for data transmission control.

A major advantage of TDMA is that the radio part of the mobile-only needs to listen and broadcast for its own time slot.

CDMA, by comparison, supports "soft hand-off" which allows a mobile phone to be in communication with up to 6 base stations simultaneously, a type of "same-frequency handover".

A disadvantage of TDMA systems is that they create interference at a frequency that is directly connected to the time slot length.