LTE, LTE-Advanced and WiMAX: Towards IMT-Advanced Networks

Overview of Part II

Frame Structure

Chapter 10 will discuss the frame structure in both LTE and LTE-Advanced. In TDD, only one carrier frequency is used for uplink and downlink transmission where the uplink and downlink transmissions are only isolated in time. The TDD frame, also known as type 2 frame, is divided between the two transmissions using a guard period which is required to switch between the them. In every frame, either one or two sub-frames are split into a downlink part called DwPTS, a guard period, and an uplink part called UpPTS to facilitate the switching from downlink to uplink or vice versa. Other sub-frames are either allocated to uplink or downlink transmissions. The only exception is that sub-frames 0 and 5 are always allocated to downlink transmission.

UE States and State Transitions

3GPP extensively defines procedures for camping and network entry in LTE and LTE-Advanced. These are described in Chapter 11.

In LTE, a UE is required to perform certain steps in order to join a specific cell after being switched on. These steps compose the initial access procedure according to the LTE terminology. In particular, these are:

1. Cell search and cell selection;
2. Receiving system information; and
3. Random access procedure.

Cell search is the process by which a UE acquires time and frequency synchronizations with a cell and detects eNB's ID. Acquiring the cell ID is by itself a two-stage process. First, the cell ID needs to be identified, and second the cell ID group is ...