In order that the 3G LTE system can maintain synchronization and the system is able to manage the different types of information that need to be carried between the base-station or eNodeB and the User Equipment, UE, 3G LTE system has a defined LTE frame and subframe structure
The frame structures for LTE differ between the Time Division Duplex, TDD and the Frequency Division Duplex, FDD modes as there are different requirements on segregating the transmitted data.
There are two types of LTE frame structure:
Type 1: used for the LTE FDD mode systems.
Type 2: used for the LTE TDD systems.
Type 1 LTE Frame Structure
The basic type 1 LTE frame has an overall length of 10 ms. This is then divided into a total of 20 individual slots. LTE Subframes then consist of two slots - in other words there are ten LTE subframes within a frame.
Type 2 LTE Frame Structure
The frame structure for the type 2 frames used on LTE TDD is somewhat different. The 10 ms frame comprises two half frames, each 5 ms long. The LTE half-frames are further split into five subframes, each 1ms long.
