5G NR: What is SSB in 5G

What is SSB in 5G?

My friend: Hi Ibrahim, I have a question for you.

Me: Please, go ahead.

My friend: I was wondering what is meant by SSB in 5G?

Me: SSB (Synchronization Signal/PBCH block) is used during the cell search procedure, i.e. UE search for Synchronization Signals when scanning for a cell to camp on, then UE decodes the PBCH before proceeding to decode other system information which is transmitted on the PDSCH. SSB Blocks are also used for RSRP, RSRQ and SINR measurements. The SSB Block is sent in DL direction occupying 20 Resource Blocks in the frequency domain and 4 symbols in the time domain. It includes the Primary Synchronization Signal (PSS), the Secondary Synchronization Signal (SSS) and the Physical Broadcast Channel (PBCH).

My friend: So, is it similar to LTE?

Me: Not exactly as in LTE, we have also PSS, SSS and PBCH but their time domain position and periodicity are fixed and also frequency domain position is fixed as well. While in 5G, the time domain and frequency domain position can vary depending on the subcarrier spacing and other different higher layer parameters. Please check the below snapshot.