TDD
full spelling ： Time Division Duplex
Time Division Duplex is system where single frequency channel is assigned to both the transmitter and the receiver. Both the uplink and downlink traffic use the same resources but at different times. It emulates full duplex communication over a half duplex communication link.
The main advantage of Time Division Duplex is, as the amount of uplink data increases, more bandwidth can dynamically be allocated to that and as it shrinks it can be taken away. TDD allows dynamic bandwidth allocation.