Advantages of TDMA over FDMA

A TDMA cellular system shares one carrier among several users in time slots, while FDMA gives each user its own carrier. TDMA has these advantages over FDMA:

1. Fewer transceivers – one radio at the base station serves several users (8 in GSM), reducing cost and size.
2. No duplexer needed – transmit and receive happen in different time slots, so the handset is simpler.
3. Battery saving – the mobile transmits only in its slot (discontinuous transmission) and can switch off its transmitter between bursts.
4. Mobile-assisted handoff (MAHO) – during idle slots the mobile measures signal strength of neighbouring base stations, giving faster and more reliable handoff.
5. Flexible bit rate – a user can be given several slots for higher data rates (e.g. GPRS, HSCSD).
6. Higher capacity / spectral efficiency – digital coding, speech compression and better reuse give more users per MHz than analog FDMA.
7. Fewer guard bands and simpler filtering – wide carriers mean fewer channel edges; less adjacent-channel interference from intermodulation.
8. Digital features – easy encryption, error control coding and data services.