In 5G New Radio (NR), SSB stands for Synchronization Signal Block. The SSB is a crucial component for initial access procedures, enabling User Equipments (UEs) to detect the presence of a 5G network, achieve time and frequency synchronization, and obtain essential information required to connect to the network.

The SSB is broadcast periodically by the gNB (5G base station), allowing UEs to perform cell search and selection procedures as they enter the network coverage area or when they need to reselect a cell. The periodicity and transmission of SSBs are designed to ensure that UEs can quickly and efficiently find the necessary signals for synchronization and initial access, even in challenging radio conditions or when moving at high speeds.

In short, the SSB in 5G NR is a fundamental set of signals that facilitates initial UE synchronization with the network, providing the necessary information for UEs to proceed with further system access procedures.

The SSB consists of the following elements:

• Primary Synchronization Signal (PSS): Helps UEs achieve time synchronization with the cell. The PSS aids in identifying the cell's symbol timing and frame boundary.
• Secondary Synchronization Signal (SSS): Provides additional synchronization information, including the cell ID within a cell group, enabling the UE to identify and distinguish between different cells. It also assists in completing the cell search process initiated by the PSS.
• Physical Broadcast Channel (PBCH): Carries the Master Information Block (MIB), which includes essential system information that the UE needs for initial system access, such as the System Frame Number (SFN) and the subcarrier spacing for the downlink.
• Demodulation Reference Signal (DMRS) for PBCH: Associated with the PBCH, this reference signal is used for channel estimation to accurately demodulate the PBCH.

Further Readings

• SS Block