(1) What is the primary function of DMRS for PBCH?
(2) How and where is it being transmitted?
(3) Where is it being allocated within S1, S2, and S3, and what overhead is added by DMRS for PBCH?
(1) What is the primary function of DMRS for PBCH?
– The UE uses DMRS to estimate the propagation channel experience by the PBCH. The resultant information is used to demodulate the PBCH and subsequently decode the Master Information Block.
(2) How and where is it being transmitted?
– The DMRS for the PBCH is transmitted by the Base Station using antenna port 4000. (PBCH is transmitted within SSB Block in Symbols 1, 2, and 3, as shown below.
– There are no Resource Elements for the DMRS within the first symbol(S0), as the PBCH does not use this symbol.
(3) Where is it being allocated within S1, S2, and S3, and what overhead is added by DMRS for PBCH?
– The DMRS is allocated to every 4th Resource element and is designed based on PCI mod 4.
– DMRS Occupy 25% of the PBCH REs Per Resource Block,
*Where S1/S3 = 20RB * 3 DMRS RE = 60RE, and S2= 8RB * 3 DMRS RE = 24RE
*RB: Resource Block, RE: Resource elements
