TDMA

TDMA, or Time Division Multiple Access, is a channel access method used in telecommunications to share a single frequency channel among multiple users by dividing each channel into sequential time slots. In a TDMA system, a fixed frame structure is created; each frame contains a set number of timeslots. Each user is assigned one or more timeslots within each frame, and only transmits during its allocated slot. This requires precise time synchronization across the network so transmissions align with the slot boundaries, with guard bands to tolerate timing variations and prevent overlap.

In operation, the transmitter is active only in its assigned slot, allowing several users to use the same frequency channel without simultaneous transmissions. This increases spectral efficiency compared with a pure single-user channel. TDMA is commonly implemented with fixed slot assignments, though some systems use dynamic or semi-dynamic slot allocation to accommodate varying traffic.

Applications and examples: TDMA has been widely used in mobile networks, most notably in GSM, where each radio carrier is divided into eight timeslots per frame. It has also been employed in various satellite and terrestrial trunked radio systems, and in some digital VSAT networks.

Advantages include efficient use of available spectrum and simpler transceiver design relative to some other multiple-access schemes. Disadvantages involve strict timing synchronization requirements, potential latency related to frame length, and reduced efficiency for highly bursty data due to fixed slot allocation and guard intervals. TDMA coexists with other access methods such as FDMA and CDMA, each with different trade-offs.