Synchronization & BCH for TDD Frame in LTE
- Synchronization:
- Purpose: Achieves alignment between the base station (eNodeB) and User Equipment (UE) in LTE Time-Division Duplex (TDD) frames.
- Methods: Time synchronization ensures proper timing, and frequency synchronization aligns the carrier frequency.
- Importance: Synchronization is critical for avoiding interference and optimizing signal reception.
- Broadcast Channel (BCH):
- Function: Carries essential system information, including cell identity, bandwidth, and frame configuration.
- Location: Positioned in the first subframe of each TDD frame for downlink transmission.
- Critical for UE Initialization: Enables UEs to identify and synchronize with the serving cell.
In LTE TDD frames, synchronization ensures proper alignment between base stations and UEs, while the BCH carries vital system information for initialization and communication between network elements and user devices.
- The Primary synchronization signal (PSS): is placed at the third symbol in subframes #1 and #6.
- The secondary synchronization signal (SSS): is placed at the last symbol in subframes #0 and #5.
- The S-RACH is transmitted on the UpPTS within the special frame.
- The Primary Broadcast Channel (P-BCH) and the Dynamic Broadcast Channel (DBCH):
are located as in LTE FDD.
Random access typically uses one of the normal subframes as in FDD, allowing for a relatively long random-access preamble providing coverage and capacity also in large cells. However, in scenarios where random-access coverage is not an issue, a short random access preamble in the UpPTS can be used instead.