The difference between tdd and fdd is that GSM, CDMA and WCDMA systems are typical fdd systems, while TDSCDMA is a tdd system. Then it is difficult for fdd technology to estimate downlink with uplink signal, and it is also impossible to estimate uplink with downlink signal.

Tdd technology does not need transceiver isolator, only needs a switch.

The characteristic of Fdd frequency division duplex is that the system receives and transmits on two symmetrical frequency channels that separate WCDMA uplink and downlink frequency intervals 190MHz, ensuring that the frequency band is used to separate the receiving and transmitting channels.