To synchronize with the cell and decode the Master Information Block (MIB), UE has to decode the SSB block which consists of PSS, SSS, PBCH, and PBCH DMRS.
The SS portion of the SS/PBCH block contains the Primary Synchronization Signal (PSS) and the Secondary Synchronization Signal. The PBCH portion of the SS/PBCH block contains the Master Information Block (MIB) and Demodulation Reference Signals (PBCH DM-RS) which serves as a reference for demodulating the MIB. The SS/PBCH block is repeated every 2 frames (TS 38.213 Section 4.1 Release 15) which is a time period of 20 msec.
Why are SSB measurements essential in 5G NR?
- The UE uses the SSB for 5G NR cell search and synchronization.
- The UE measurements on the different SSBs are essential to determine the right beam configuration for data transmission (based on a UE / CPE / gNB internal algorithm).
- The SSB is always there (at least once per 5G NR carrier) and the sequence is known.
- Therefore it‘s perfect for
- Coverage measurement.
- Interference measurement.
- Beamforming evaluation.