HOW DOES THE TIME-DOMAIN STRUCTURE LOOK FOR LTE FDD?
The figure below illustrates the high-level time-domain structure for LTE Frequency Division Duplexing (FDD) transmission.
The figure is valid for both the downlink and uplink transmission direction from time domain perspective. Each (radio) frame of length T f = 10 ms consists of ten equally-sized sub frames of length Tsub-frame = 1 ms.
Each sub-frame, in turn, consists of two equally-sized slots of length Tslot = 0.5 ms. The sub-frame is the typical scheduling unit of LTE, while the slots are relevant in case of frequency hopping. In the FDD case, all slots of a carrier are available for downlink transmission (in case of a downlink carrier) or uplink transmission (in case of an uplink carrier).