Hi, for SS/PBCH SCS 30Khz there two option case B and case C having different symbol mapping in time domain.
What is condition or use case based on which network choose either one?
Hi Experts.
Question about 5G SSB too…
In the picture below which parameter dictates if case B or case C is used:
Link is here:
https://www.sharetechnote.com/html/5G/5G_FrameStructure.html#SS_PBCH_TimeDomainResourceAllocation
Thanks I will have a look.
Do you happen to know how is it for n78? Case b or case C?
Should be Case C.
I think also can be verified from PDSCH resource allocation, RBG should not be present at SSB location.
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To my understanding case type will be selected based on SCS and Frequency at which UE is capable of operating.
Ex : If SCS = 15khz case A selected and respective starting symbols of SSB will be selected based on frequency.
Hope I have answered your queries.
The fundamental difference between case B and case C
The fundamental difference is the symbol location of ssburst.
For case B, ssburst takes symbols [4,5,6,7 & 8,9,10,11 …] whereas for case C, ssburst takes symbols [2,3,4,5 & 8,9,10,11,…]. You can notice that in case C, there is a 2 OFDM symbol gap between 2 consecutive SSBlocks. Therefore:
- In case B since there are 4 available OFDM symbols in the front you can have a 3-symbol PDCCH allocation, which is not possible in case C.
- In case C since there are 2 OFDM symbols [symbol 6 & 7] available in between 2 SSBlocks, you have symbol 6 for TDD switching and symbol 7 as UL symbol for ACK/NACKs. This way you can facilitate URLLC communication.
SSB Class as per band
Case B and Case C are specified in the 3gpp specification as per the band. As per the below image from 38.101-1 and 38.101-2 for every band [range of the frequency], SSB class is fix.
FR1
For FR2
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